Characteristic features of common causes of bacterial meningitis

     

    Organism Site of entry Age range Predisposing conditions
    Neisseria meningitidis Nasopharynx All ages Usually none, rarely complement deficiency
    Streptococcus pneumoniae Nasopharynx, direct extension across skull fracture, or from contiguous or distant foci of infection All ages All conditions that predispose to pneumococcal bacteremia, fracture of cribriform plate, cochlear implants, cerebrospinal fluid otorrhea from basilar skull fracture, defects of the ear ossicle (Mondini defect)
    Listeria monocytogenes Gastrointestinal tract, placenta Older adults and neonates Defects in cell-mediated immunity (eg, glucocorticoids, transplantation [especially renal transplantation]), pregnancy, liver disease, alcoholism, malignancy
    Coagulase-negative staphylococci Foreign body All ages Surgery and foreign body, especially ventricular drains
    Staphylococcus aureus Bacteremia, foreign body, skin All ages Endocarditis, surgery and foreign body, especially ventricular drains; cellulitis, decubitus ulcer
    Gram-negative bacilli Various Older adults and neonates Advanced medical illness, neurosurgery, ventricular drains, disseminated strongyloidiasis
    Haemophilus influenzae Nasopharynx, contiguous spread from local infection Adults; infants and children if not vaccinated Diminished humoral immunity

     

 Meningitis is an inflammatory disease of the leptomeninges.

Meningitis reflects infection of the arachnoid mater and the CSF in both the subarachnoid space and the cerebral ventricles.

 

The bacteria that cause meningococcal meningitis live within the nose and throat. One in 10 people carry the bacteria with no signs or symptoms of disease.

Occurs, primarily in patients over age 50 to 60 years or those who have deficiencies in cell-mediated immunity,

In rare cases, the bacteria can invade the body and lead to meningococcal disease. Those who carry the bacteria can spread the bacteria easily from person to person through close contact, such as kissing, coughing, or sneezing.

Everyday behaviors can increase the risk of getting meningococcal meningitis, especially for teens and young adults, including:

Kissing

Coughing & sneezing

Living in close quarters

Sharing drinks & eating utensils

Smoking & secondhand smoke

Approximately 1.2 million cases of bacterial meningitis occur annually worldwide [1]. Meningitis is among the 10 most common infectious causes of death and is responsible for approximately 135,000 deaths throughout the world each year. Neurologic sequelae are common among survivors.

 

 

Bacterial meningitis is a medical emergency.

 Time to antibiotics has a profound effect on clinical outcomes. Maintain a high index of suspicion and not delay treatment while diagnostic studies are being completed.

Diagnosis

[The cornerstone of the diagnosis of meningitis is the CSF analysis, which is obtained by lumbar puncture (LP). LP can confirm the presence of inflammatory cells in the CSF, identify the causative organism by Gram stain and culture, and evaluate for other potential causes of the patient’s symptoms (idiopathic intracranial hypertension, subarachnoid hemorrhage, autoimmune disease, etc.). If a delay in performing the LP is expected, then blood cultures and empiric antibiotics with dexamethasone should be administered PRIOR to obtaining the CSF. A common cause for delay of diagnosis is the time it takes to obtain a computed tomography (CT) scan of the head. CT scanning prior to performing an LP is recommended for any patients with risk factors for having elevated intracranial pressure, which may increase the risk of brain herniation during the procedure. CT scan of the head may also be indicated when searching for alternative causes for altered level of consciousness. See Table 39–1 to review guidelines for which patients should have CT before LP. Approximately 45% of patients with bacterial meningitis will meet one or more of these criteria. All other patients can safely have an LP performed without an antecedent CT scan.]

Hypotension, cerebral infarction, seizures, increased ICP) often occur in the first 2 to 3 days as therapy is administered.

1. Admit in an intensive care unit.

2. Draw blood for culture immediately.

3. Adjunctive dexamethasone therapy initiated without delay.

Given intravenously immediately before or with the first dose of antibiotics if pneumococcal meningitis is suspected (eg, if gram-positive diplococci are seen on CSF Gram stain);

Similarly, hydrocortisone should be given intravenously immediately if adrenal infarction is suspected in meningococcal meningitis with meningococcemia (eg, gram-negative diplococci are seen on CSF Gram stain; petechiae; shock).

4. Empiric intravenous antimicrobial therapy once blood cultures have been obtained and prior to head CT.

Empiric Therapy Regimens based on patient population. 

All drugs should be administered intravenously (IV). 

Age

Younger than 1 month:

Commonly observed pathogens include group B Streptococcus (GBS) (cases lack characteristic stiff neck of more typical bacterial meningitis), Escherichia coliListeria monocytogenes, and Klebsiella species.

  • Ampicillin 100 mg/kg plus  cefotaxime 50 mg/kg q6h or
  • Ampicillin 100 mg/kg plus an aminoglycoside (gentamicin 2.5 mg/kg or tobramycin 2.5 mg/kg) q8h

 

 

 

 

One to 23 months:

Commonly observed pathogens include Streptococcus pneumoniae, Neisseria meningitidis (rapidly evolving skin rash indicative of infection with Meningococcusspecies; immediately begin a regimen of benzyl penicillin, ceftriaxone, or cefotaxime), GBS, Haemophilus influenzae type b, and E coli.

  • Vancomycin 15 mg/kg q6h plus a third-generation cephalosporin (ceftriaxone 75-100 mg/kg q12-24h or cefotaxime 75-100 mg/kg q6-8h
  • Ampicillin is added for empiric Listeria coverage in patients <2 years of age.

Two to 50 years:

Commonly observed pathogens include N meningitides, and S pneumoniae. Adult and pediatric dosing should include vancomycin plus a third-generation cephalosporin (eg, ceftriaxone, cefotaxime).

  • Children: Vancomycin 15 mg/kg q6h plus  ceftriaxone 75-100 mg/kg q12-24h orcefotaxime 75-100 mg/kg q6-8h
  • Adults: Vancomycin 15 mg/kg q8h (to achieve trough levels of 15-20 ug/mL)plus  ceftriaxone 2 g q12h or cefotaxime 2 g q4h

Older than 50 years:

Commonly observed pathogens include S pneumoniae, N meningitidis, L monocytogenes, and aerobic gram-negative rods.

  • Vancomycin 15 mg/kg q8h (to achieve trough levels of 15-20 ug/mL) plus ampicillin 2 g q 4h (hourly if Listeria is suspected) [1plus  a third-generation cephalosporin (ceftriaxone 2 g q12h or cefotaxime 2 g q4-6h)

Conditions to consider on giving antibiotic therapy

Pregnancy:

Commonly observed pathogens include L monocytogenes.

  • Ampicillin 2 g q4h or penicillin G 4 mU q4h

Immunocompromised (eg, chemotherapy, steroids):

Commonly observed pathogens include S pneumoniae, N meningitidis, Listeriaspecies, and anaerobic gram-negative bacilli.

  • Vancomycin 15 mg/kg q8h (to achieve trough levels of 15-20 ug/mL) plus ampicillin 2 g q4h plus a third-generation cephalosporin (ceftriaxone 2 g q12h or cefotaxime 2 g q4-6h)

Basilar skull fracture:

Commonly observed pathogens include S pneumoniae, H influenzae, and Streptococcus pyogenes.

  • Vancomycin 15 mg/kg q8h (to achieve trough levels of 15-20 ug/mL) plus a third-generation cephalosporin (ceftriaxone 2 g q12h or cefotaxime 2 g q4-6h)

Penetrating trauma or post neurosurgery:

Commonly observed pathogens include Staphylococcus aureus, Staphylococcus epidermidis, and aerobic gram-negative bacilli.

  • Vancomycin 15 mg/kg q8h (to achieve trough levels of 15-20 ug/mL) plus cefepime 2 g q8h or  ceftazidime 2 g q8h or meropenem 2 g q8h

Cerebrospinal fluid (CSF) shunt:

Commonly observed pathogens include S epidermidis, S aureus, aerobic gram-negative bacilli, and Propionibacterium acnes.

  • Vancomycin 15 mg/kg q8h (to achieve trough levels of 15-20 ug/mL) plus cefepime 2 g q8h or  ceftazidime 2 g q8h or meropenem 2 g q8h

.

 

Acyclovir should be considered according to the results of the initial cerebrospinal fluid (CSF) evaluation.

Doxycycline should also be added during tick season in endemic areas.

The treatment duration is 7 days.1

 

Duration of therapy is 10 to 14 days in documented cases of bacterial meningitis.
Further antimicrobial therapy is guided by cultures and susceptibility testing.

 

.

 

 

 

5. Head CT

Indications for CT scan before LP. (CT) scan is performed to exclude a mass lesion or increased intracranial pressure; these abnormalities might rarely lead to cerebral herniation during removal of large amounts of CSF, and have devastating consequences.

—  patients with evidence of raised intracranial pressure (eg, mass effect on CNS imaging or clinical signs of impending herniation), thrombocytopenia or another bleeding diathesis, or spinal epidural abscess.

6. Lumbar Puncture

[The diagnosis of bacterial meningitis is made by examination of the CSF (Table 133-2). The need to obtain neuroimaging studies (CT or MRI) prior to lumbar puncture (LP) requires clinical judgment. In an immunocompetent patient with no known history of recent head trauma, a normal level of consciousness, and no evidence of papilledema or focal neurologic deficits, it is considered safe to perform LP without prior neuroimaging studies. If LP is delayed in order to obtain neuroimaging studies, empirical antibiotic therapy should be initiated after blood cultures are obtained. Antibiotic therapy initiated a few hours prior to LP will not significantly alter the CSF WBC count or glucose concentration, nor is it likely to prevent visualization of organisms by Gram’s stain or detection of bacterial nucleic acid by polymerase chain reaction (PCR) assay.]

5. Fluid and electrolyte resuscitation must be administered to attain appropriate blood pressure and cerebral perfusion.

If the patient does not have hypovolemia or shock upon admission, there may be a role for modest fluid restriction until SIADH can be ruled out, especially if the serum sodium is less than 130 mEq/L (130 mmol/L). SIADH can cause hyponatremia and hypo-osmolality, which could lead to mental confusion, lethargy, seizures, and increased ICP. (20) If SIADH is suspected, serum and urine osmolalities should also be monitored. Fluid restriction can be gradually removed when the sodium concentration reaches 135 mEq/L (135 mmol/L), often within 24 to 48 hours after hospitalization.

The child’s weight, serum electrolytes, urine output, and urine specific gravity should be monitored closely in the first 24 to 36 hours of hospitalization.

Mild early signs of increased ICP can be managed by elevating the head of the bed. However, severe signs of increased ICP (apnea, bradycardia, hypertension, sluggish or dilated pupils) require more aggressive therapy with mannitol and hyperventilation.

Generalized seizures occur early in the disease course in 20% to 25% of meningitis cases and can usually be controlled with standard seizure medications, such as fosphenytoin or phenobarbital. Focal seizures, difficult-to-control seizures, or seizures occurring more than 48 hours after admission should prompt a neurology consultation.

If a subdural empyema develops, drainage is usually necessary. Subdural empyema can present as persistent fever, headache, and nuchal rigidity or new onset of neurologic features, such as seizures, in the setting of appropriate antibiotic treatment.

6. Lumbar Puncture

A CT scan of the head before LP should be performed in adult patients with suspected bacterial meningitis who have one or more of the following risk factors [1-3]:

●Immunocompromised state (eg, HIV infection, immunosuppressive therapy, solid organ or hematopoietic stem cell transplantation)

●History of central nervous system (CNS) disease (mass lesion, stroke, or focal infection)

●New onset seizure (within one week of presentation)

●Papilledema

●Abnormal level of consciousness

●Focal neurologic deficit

  • clinical signs of impending herniation (ie, deteriorating level of consciousness, particularly a Glasgow coma scale <11; brainstem signs including pupillary changes, posturing, or irregular respirations; or a very recent seizure) may be predictive of patients in whom an LP should be delayed.

The major drawback to requiring a CT scan before LP is that initiation of antibiotics is often delayed. The bacterial meningitis guidelines in Sweden were revised in 2009 to remove impaired mental status as a contraindication to LP without prior CT scan, and the effect of this change was evaluated in a retrospective study using the Swedish quality registry [31]. After the change to the guidelines was implemented, adequate treatment was started 1.2 hours earlier, and more patients were treated within 2 hours of presentation; in addition, mortality was lower (7 versus 12 percent), and the risk of sequelae at follow-up was decreased (38 versus 49 percent) following the change to the guidelines. Those who underwent immediate LP without CT received antibiotics 1.6 hours earlier than those who underwent CT prior to LP. Treatment delay resulted in a significantly increased risk of fatal outcome, with a relative increase in mortality of 13 percent per hour of delay.

If LP is delayed or deferred, blood cultures should be obtained and antimicrobial therapy should be administered empirically before the imaging study, followed as soon as possible by the LP. In addition, dexamethasone (0.15 mg/kg intravenously [IV] every six hours) should be given shortly before or at the same time as the antimicrobial agents if the preponderance of clinical and laboratory evidence suggests bacterial meningitis with a plan to stop therapy, if indicated, when the evaluation is complete. Adjunctive dexamethasone should not be given to patients who have already received antimicrobial therapy because it is unlikely to improve patient outcome [29]. (See "Dexamethasone to prevent neurologic complications of bacterial meningitis in adults" and "Initial therapy and prognosis of bacterial meningitis in adults", section on 'Avoidance of delay'.)

Prior administration of antimicrobials tends to have minimal effects on the chemistry and cytology findings [24,32] but can reduce the yield of Gram stain and culture [23-25]. However, a pathogen can still be cultured from the CSF in most patients up to several hours after the administration of antimicrobial agents [24,25], with the possible exception of the meningococcus. This issue was addressed in a review of 128 children with bacterial meningitis in whom LP was first performed after initiation of therapy and serial LPs were obtained [25]. Among patients with meningococcal infection, CSF culture was negative in three of nine samples obtained within one hour. In contrast, 4 to 10 hours were required before CSF cultures were sterile in patients with pneumococcal meningitis.

Relative contraindications — Although there are no absolute contraindications to performing an LP, caution should be used in patients with evidence of raised intracranial pressure (eg, mass effect on CNS imaging or clinical signs of impending herniation), thrombocytopenia or another bleeding diathesis, or spinal epidural abscess.

Opening pressure — 

The opening pressure is typically elevated in patients with bacterial meningitis. (normal up to 200 mm H2O) [2].

The opening pressure is measured with the patient lying in the lateral decubitus position.

 

If the results of the CT reveal that LP is contraindicated, therapy for bacterial meningitis should be continued (if indicated) or

[ evaluation and treatment for an alternative diagnosis should be undertaken (ie, if the CT suggests a different cause for the patient's clinical presentation).]

In patients without any of the risk factors described above, blood cultures and LP may be performed without performing a head CT. Once CSF has been obtained (and before results are available), dexamethasone (if indicated) and empiric antimicrobial therapy should be initiated if bacterial meningitis is suspected.

In an immunocompetent patient with no known history of recent head trauma, a normal level of consciousness, and no evidence of papilledema or focal neurologic deficits, it is considered safe to perform LP without prior neuroimaging studies.

If LP is delayed in order to obtain neuroimaging studies, empirical antibiotic therapy should be initiated after blood cultures are obtained. Antibiotic therapy initiated a few hours prior to LP will not significantly alter the CSF WBC count or glucose concentration, nor is it likely to prevent visualization of organisms by

CSF should be sent for:

•Cell count and differential

•Glucose concentration

•Protein concentration

•Gram stain and bacterial culture

•Other appropriate tests, depending upon the level of concern for other etiologies of meningitis or meningoencephalitis

Characteristic findings in bacterial meningitis include a CSF glucose concentration <40 mg/dL, a CSF to serum glucose ratio of ≤0.4, a protein concentration >200 mg/dL, and a white blood cell count above 1000/microL, usually composed primarily of neutrophils.

 

However, the spectrum of CSF values in bacterial meningitis is so wide that the absence of one or more of these findings is of little value (table 1) [1-3]. This was illustrated in a review of 296 episodes of community-acquired bacterial meningitis: 50 percent had a CSF glucose above 40 mg/dL (2.2 mmol/L), 44 percent had a CSF protein below 200 mg/dL, and 13 percent had a CSF white cell count below 100/microL [3]. In another series of 696 episodes of community-acquired bacterial meningitis, 12 percent had none of the characteristic CSF findings [8]. (See "Clinical features and diagnosis of acute bacterial meningitis in adults", section on 'CSF analysis'.)

 

●The frequent absence of one or more of the expected CSF findings in patients with bacterial meningitis means that there is substantial overlap between bacterial meningitis, which is a life-threatening illness that requires hospital admission and urgent therapy, and viral meningitis, which is a less severe disease that is often monitored in the outpatient setting without antimicrobial therapy. Selected viruses that can cause meningitis are summarized in the Table (table 2). The diagnostic approach to aseptic meningitis is presented separately. (See "Aseptic meningitis in adults".)

 

●Before CSF results are available, it can be difficult to know whether the patient has bacterial or viral meningitis. The decision of which tests to perform on the CSF will depend on patient-specific factors, such as those described above (see 'History' above). In addition to suggesting specific diagnostic tests, we often send an extra tube of CSF if possible to the laboratory to be held for further studies, as the CSF profile and the patient's clinical course may warrant additional testing.

Gram’s stain or detection of bacterial nucleic acid by polymerase chain reaction (PCR) assay.

 

____________________________________

 
 

 

 

 

[Antibiotics used in Empirical Therapy of Bacterial Meningitis and Focal Central Nervous System Infectionsa

Indication Antibiotic
Infants 1–3 months Ampicillin + cefotaxime or ceftriaxone
Immunocompetent children >3 months and adults <55 Cefotaxime, ceftriaxone, or cefepime + vancomycin
Adults >55 and adults of any age with alcoholism or other debilitating illnesses Ampicillin + cefotaxime, ceftriaxone or cefepime + vancomycin
Hospital-acquired ­meningitis, posttraumatic or postneurosurgery meningitis, neutropenic patients, or patients with impaired cell-mediated immunity Ampicillin + ceftazidime or meropenem + vancomycin
 
Total Daily Dose and Dosing Interval
Antimicrobial Agent Child (>1 month) Adult
Ampicillin 300 (mg/kg)/d, q6h 12 g/d, q4h
Cefepime 150 (mg/kg)/d, q8h 6 g/d, q8h
Cefotaxime 225-300 (mg/kg)/d, q6h 12 g/d, q4h
Ceftriaxone 100 (mg/kg)/d, q12h 4 g/d, q12h
Ceftazidime 150 (mg/kg)/d, q8h 6 g/d, q8h
Gentamicin 7.5 (mg/kg)/d, q8hb 7.5 (mg/kg)/d, q8h
Meropenem 120 (mg/kg)/d, q8h 6 g/d, q8h
Metronidazole 30 (mg/kg)/d, q6h 1500–2000 mg/d, q6h
Nafcillin 100–200 (mg/kg)/d, q6h 9–12 g/d, q4h
Penicillin G 400,000 (U/kg)/d, q4h 20–24 million U/d, q4h
Vancomycin 45-60 (mg/kg)/d, q6h 45-60 (mg/kg)d, q6–12hb

aAll antibiotics are administered intravenously; doses indicated assume normal renal and hepatic function.

bDoses should be adjusted based on serum peak and trough levels: gentamicin therapeutic level: peak: 5–8 μg/mL; trough: <2 μg/mL; vancomycin ­therapeutic level: peak: 25–40 μg/mL; trough: 5–15 μg/mL.


 

 

 

 

 

 

Bacterial meningitis can be community acquired or healthcare associated.

Community Acquired

The major causes of community-acquired bacterial meningitis in adults in developed countries are Streptococcus pneumoniae, Neisseria meningitidis, and, primarily in patients over age 50 to 60 years or those who have deficiencies in cell-mediated immunity, Listeria monocytogenes (table 1).

Characteristic features of common causes of bacterial meningitis
Organism Site of entry Age range Predisposing conditions
Neisseria meningitidis Nasopharynx All ages Usually none, rarely complement deficiency
Streptococcus pneumoniae Nasopharynx, direct extension across skull fracture, or from contiguous or distant foci of infection All ages All conditions that predispose to pneumococcal bacteremia, fracture of cribriform plate, cochlear implants, cerebrospinal fluid otorrhea from basilar skull fracture, defects of the ear ossicle (Mondini defect)
Listeria monocytogenes Gastrointestinal tract, placenta Older adults and neonates Defects in cell-mediated immunity (eg, glucocorticoids, transplantation [especially renal transplantation]), pregnancy, liver disease, alcoholism, malignancy
Coagulase-negative staphylococci Foreign body All ages Surgery and foreign body, especially ventricular drains
Staphylococcus aureus Bacteremia, foreign body, skin All ages Endocarditis, surgery and foreign body, especially ventricular drains; cellulitis, decubitus ulcer
Gram-negative bacilli Various Older adults and neonates Advanced medical illness, neurosurgery, ventricular drains, disseminated strongyloidiasis
Haemophilus influenzae Nasopharynx, contiguous spread from local infection Adults; infants and children if not vaccinated Diminished

Healthcare-associated

The major causes of healthcare-associated bacterial meningitis are different (usually staphylococci and aerobic gram-negative bacilli) and, in cases occurring after neurosurgery, may vary with whether or not antimicrobial prophylaxis has been given to prevent surgical site infection. Healthcare-associated bacterial meningitis may also occur in patients with internal or external ventricular drains or following trauma (ie, cranial trauma or after basilar skull fracture with or without clinical evidence of leak of cerebrospinal fluid).

 

 

 

 

●The major causes of community-acquired bacterial meningitis in adults in developed countries are Streptococcus pneumoniae, Neisseria meningitidis, and, primarily in patients over age 50 to 60 years or those who have deficiencies in cell-mediated immunity, Listeria monocytogenes (table 1).

 

●The major causes of healthcare-associated bacterial meningitis are different (usually staphylococci and aerobic gram-negative bacilli) and, in cases occurring after neurosurgery, may vary with whether or not antimicrobial prophylaxis has been given to prevent surgical site infection. Healthcare-associated bacterial meningitis may also occur in patients with internal or external ventricular drains or following trauma (ie, cranial trauma or after basilar skull fracture with or without clinical evidence of leak of cerebrospinal fluid).

1

 

 

Complications due to bacterial meningitis can be divided into systemic and neurologic. Systemic complications, such as septic shock, disseminated intravascular coagulation, acute respiratory distress syndrome, and septic or reactive arthritis, are usually the consequence of the bacteremia that frequently accompanies meningitis [1].

The neurologic complications of bacterial meningitis include:

●Impaired mental status

●Increased intracranial pressure and cerebral edema

●Seizures

●Focal neurologic deficits (eg, cranial nerve palsy, hemiparesis)

●Cerebrovascular abnormalities

●Sensorineural hearing loss

●Intellectual impairment

The mortality rate of untreated disease approaches 100 percent, and, even with optimal therapy, there is a high failure rate.

Despite the effectiveness of current antibiotics in clearing bacteria from the cerebrospinal fluid (CSF), bacterial meningitis continues to cause significant morbidity and mortality worldwide. In two large case series, for example, the case-fatality rate for adults with bacterial meningitis was approximately 25 percent, and transient or permanent neurologic morbidity occurred in 21 to 28 percent of survivors1,2

From its original recognition in 1805 until the early 1900s, bacterial meningitis was virtually 100 percent fatal. In 1913, Simon Flexner's introduction of intrathecal meningococcal antiserum prevented some deaths, but the clinical outcome did not improve dramatically until the advent of systemic antimicrobial therapy in the 1930s.1

Content 11

 

Raised ICP is the major cause of obtundation and coma in this disease. More than 90% of patients will have a CSF opening pressure >180 mmH2O, and 20% have opening pressures >400 mmH2O.

The most disastrous complication of increased ICP is cerebral herniation. The incidence of herniation in patients with bacterial meningitis has been reported to occur in as few as 1% to as many as 8% of cases.Seizures occur as part of the initial presentation of bacterial meningitis or during the course of the illness in 20–40% of patients. Focal seizures are usually due to focal arterial ischemia or infarction, cortical venous thrombosis with hemorrhage, or focal edema. Generalized ­seizure activity and status epilepticus may be due to hyponatremia, cerebral anoxia, or, less commonly, the toxic effects of antimicrobial agents.

Early intravenous administration of glucocorticoids (usually dexamethasone) has been evaluated as adjuvant therapy in an attempt to diminish the rate of hearing loss and other neurologic complications as well as mortality in selected patients with bacterial meningitis.



  •  Examination of the cerebrospinal fluid (CSF) is crucial for establishing the diagnosis of bacterial meningitis, identifying the causative organism, and performing in vitro susceptibility testing [26].

    CSF analysis including Gram stain and culture will help differentiate between bacterial and viral infection if the Gram stain and/or culture is positive. Normal CSF values are less than 50 mg/dL of protein, a CSF-to-serum glucose ratio greater than 0.6, less than 5 white blood cells/microL, and a lactate concentration less than 3.5 mEq/L.

    There are some CSF findings that, in the appropriate clinical setting (eg, unexplained fever and headache), are highly suggestive of bacterial meningitis. The usual CSF findings in patients with bacterial meningitis are a white blood cell count of 1000 to 5000/microL (range of <100 to >10,000) with a percentage of neutrophils usually greater than 80 percent, protein of >200 mg/dL, and glucose <40 mg/dL (with a CSF:serum glucose ratio of ≤0.4). (See "Cerebrospinal fluid: Physiology and utility of an examination in disease states", section on 'CSF in CNS infection'.)

    An observational study found that bacterial meningitis was highly probable (≥99 percent certainty) when any one of the following parameters was present: a CSF glucose concentration below 34 mg/dL (1.9 mmol/L), a protein concentration above 220 mg/dL, a white blood cell count above 2000/microL, or a neutrophil count more than 1180/microL [33]. However, clinicians must recognize that many exceptions exist and that empiric antimicrobial therapy is warranted when bacterial meningitis is suspected clinically even if the CSF abnormalities are not diagnostic.

    Determination of the CSF lactate concentration has been suggested as a useful test to differentiate bacterial from viral meningitis. Two meta-analyses that included 25 studies (1692 patients) and 31 studies (1885 patients) concluded that the diagnostic accuracy of CSF lactate was superior to that of CSF white blood cell count, glucose, and protein concentration in differentiating bacterial from aseptic meningitis [34,35], although sensitivity was lower in patients who received antimicrobial treatment prior to lumbar puncture [35], and CSF lactate may be elevated in patients with other CNS diseases.

    Pleocytosis — It is important to note that a false-positive elevation of the CSF white blood cell (WBC) count can be found after traumatic lumbar puncture or in patients with intracerebral or subarachnoid hemorrhage in which both red blood cells and white blood cells are introduced into the subarachnoid space. If a traumatic lumbar puncture is suspected and the peripheral WBC count is not abnormally low or high, a good rule of thumb for estimating the adjusted WBC count is to subtract one WBC for every 500 to 1500 red blood cells (RBCs) measured in the CSF. The formula in the following calculator can also be used to determine the adjusted WBC count in the presence of CSF RBCs (calculator 1) [36,37].

    Generalized seizures may also induce a mild transient CSF pleocytosis, although this has not been well studied [38-40]. However, CSF pleocytosis should not be ascribed to seizure activity alone unless the fluid is clear and colorless, the opening pressure and CSF glucose are normal, the CSF Gram stain is negative, and the patient has no clinical evidence of bacterial meningitis.

    Despite these typical CSF findings, the spectrum of CSF values in bacterial meningitis is so wide that the absence of one or more of the typical findings is of little value (table 4) [2-5,41]. For example, in a review of 296 episodes of community-acquired bacterial meningitis, 50 percent had a CSF glucose above 40 mg/dL (2.2 mmol/L), 44 percent had a CSF protein below 200 mg/dL, and 13 percent had a CSF white blood cell count below 100/microL [3]. In another series of 696 episodes of community-acquired bacterial meningitis, 12 percent had none of the characteristic CSF findings of bacterial meningitis [4].

    Why some patients have milder CSF abnormalities cannot usually be identified. Potential causes include early presentation, recent prior antimicrobial therapy, and neutropenia.

    Gram stain — A Gram stain should be obtained whenever there is suspicion of bacterial meningitis. It has the advantage of suggesting the bacterial etiology one day or more before culture results are available [23]. The following findings may be seen (see "Clinical microbiology review: Meningeal infections"):

    ●Gram-positive diplococci suggest pneumococcal infection (picture 1).

    ●Gram-negative diplococci suggest meningococcal infection (picture 2).

    ●Small pleomorphic gram-negative coccobacilli suggest Haemophilus influenzae infection (picture 3).

    ●Gram-positive rods and coccobacilli suggest listerial infection (picture 4A-C).

    The reported sensitivity of Gram stain for bacterial meningitis has varied from 60 to 90 percent; however, the specificity approaches 100 percent [4,41]. In the report of 696 patients with community-acquired bacterial meningitis, CSF Gram stain had a sensitivity of 80 percent and a specificity of 97 percent [4]. In the trial of 301 adults with bacterial meningitis, for example, the Gram stain was positive in 74 percent and the CSF culture was positive in 78 percent [2]. Comparable values (64 percent positive Gram stain, 77 percent positive culture) were noted in another report [5].

    The Gram stain is positive in 10 to 15 percent of patients who have bacterial meningitis but negative CSF cultures [3]. As noted above, the yield of both Gram stain and culture may be reduced by prior antibiotic therapy [23-25].

    One report evaluated the clinical findings and course of 168 patients with suspected acute meningitis and a CSF white cell count above 5/microL who had a negative Gram stain [42]. Approximately 20 percent had a comorbid disease, 15 percent were immunocompromised, and 52 percent received empiric antimicrobial therapy. A cause for the meningitis was established in 23 percent, with most being treatable (eg, syphilis, bacteremia, and Lyme disease).

    Rapid tests — Several rapid diagnostic tests have been developed to aid in the diagnosis of bacterial meningitis. Latex agglutination tests detect the antigens of the common meningeal pathogens in the CSF, although these tests are no longer routinely recommended because results do not appear to modify the decision to administer antimicrobial therapy and false-positive results have been reported [29]. An immunochromatographic test for detection of S. pneumoniae in CSF was found to be 100 percent sensitive and specific for the diagnosis of pyogenic pneumococcal meningitis [43]; the overall sensitivity is 95 to 100 percent [44]. More studies are needed, however, before this test can be routinely recommended.

    Polymerase chain reaction — Nucleic acid amplification tests, such as the polymerase chain reaction (PCR), have been evaluated in patients with bacterial meningitis. One study evaluated a multiplex PCR assay for detection of N. meningitidis, S. pneumoniae, and H. influenzae type b and had an overall specificity and positive predictive value of 100 percent; the negative predictive value was >99 percent [45]. The sensitivity and specificity of CSF PCR for the diagnosis of pneumococcal meningitis is 92 to 100 percent and 100 percent, respectively [44]. Problems with false-positive results have been reported with PCR, however, although further refinements in this technique may make it useful for the diagnosis of bacterial meningitis especially when results of CSF Gram stain and culture are negative.

    Molecular diagnosis of bacterial meningitis is discussed in greater detail separately. (See "Molecular diagnosis of central nervous system infections", section on 'Meningitis'.)

    Triage — The preceding discussion on the frequent absence of one or more of the expected CSF findings in bacterial meningitis means that there is substantial overlap between bacterial meningitis, which is a life-threatening illness that requires hospital admission, and aseptic (usually viral) meningitis, which is a less severe disease that is often monitored in the outpatient setting without antimicrobial therapy. (See "Aseptic meningitis in adults".)

    Triage should be an individualized decision that takes into account underlying host factors, the physical examination, the neurologic examination, and the findings on CSF analysis. Multivariable prediction rules have been devised. However, the 2004 Infectious Diseases Society of America guidelines on bacterial meningitis suggested that these prediction rules should not be used to make clinical decisions in individual patients [29].

    In the absence of a positive Gram stain, which has almost 100 percent specificity (ie, very few false positives), studies in both adults and children have concluded that, in the setting of an elevated CSF white blood cell count, no single CSF biochemical variable can reliably exclude bacterial meningitis [33,41,46]. (See "Cerebrospinal fluid: Physiology and utility of an examination in disease states", section on 'CSF in CNS infection' and "Aseptic meningitis in adults".)

    Similar considerations apply to the physical examination. In the series of 696 patients with bacterial meningitis cited above, only 44 percent had the classic clinical triad of fever, neck stiffness, and altered mental status [4].

     

    Lumbar puncture with examination of the CSF is indicated whenever there is any suspicion of meningitis.

    CT Before Lumbar Puncture

    A head CT should be performed before LP in adults with suspected bacterial meningitis who have one or more of the following risk factors]:

    •Immunocompromised state (eg, HIV infection, immunosuppressive therapy, solid organ or hematopoietic cell transplantation)

    •History of central nervous system (CNS) disease (mass lesion, stroke, or focal infection)

    •New-onset seizure (within one week of presentation)

    •Papilledema

    •Abnormal level of consciousness

    •Focal neurologic deficit

mental status

nuchal rigidity (pain on passive flexion of the neck),

photophobia

 

 

 Examination of the cerebrospinal fluid (CSF) is crucial for establishing the diagnosis of bacterial meningitis, identifying the causative organism, and performing in vitro susceptibility testing [26].

Indications for CT scan before LP — Every patient with suspected meningitis should have CSF obtained unless lumbar puncture (LP) is contraindicated. Although there are no absolute contraindications to performing an LP, caution should be used in patients with evidence of raised intracranial pressure (eg, mass effect on CNS imaging or clinical signs of impending herniation), thrombocytopenia or another bleeding diathesis, or spinal epidural abscess.

It is not uncommon for LP to be delayed while a computed tomographic (CT) scan is performed to exclude a mass lesion or increased intracranial pressure; these abnormalities might rarely lead to cerebral herniation during removal of large amounts of CSF, and cerebral herniation could have devastating consequences. 2004 Infectious Diseases Society of America (IDSA) guidelines for the management of bacterial meningitis, a CT scan of the head before LP should be performed in adult patients with suspected bacterial meningitis who have one or more of the following risk factors [27-29]:

●Immunocompromised state (eg, HIV infection, immunosuppressive therapy, solid organ or hematopoietic stem cell transplantation)

●History of central nervous system (CNS) disease (mass lesion, stroke, or focal infection)

●New onset seizure (within one week of presentation)

●Papilledema

●Abnormal level of consciousness

●Focal neurologic deficit

Patients with these clinical risk factors should have a CT scan to identify a possible mass lesion and other causes of increased intracranial pressure.

However, it has been suggested that a normal CT scan does not always mean that performance of an LP is safe and that certain clinical signs of impending herniation (ie, deteriorating level of consciousness, particularly a Glasgow coma scale <11; brainstem signs including pupillary changes, posturing, or irregular respirations; or a very recent seizure) may be predictive of patients in whom an LP should be delayed (table 3) [30]. (See "Lumbar puncture: Technique, indications, contraindications, and complications in adults", section on 'Cerebral herniation'.)

The major drawback to requiring a CT scan before LP is that initiation of antibiotics is often delayed. The bacterial meningitis guidelines in Sweden were revised in 2009 to remove impaired mental status as a contraindication to LP without prior CT scan, and the effect of this change was evaluated in a retrospective study using the Swedish quality registry [31]. After the change to the guidelines was implemented, adequate treatment was started 1.2 hours earlier, and more patients were treated within 2 hours of presentation; in addition, mortality was lower (7 versus 12 percent), and the risk of sequelae at follow-up was decreased (38 versus 49 percent) following the change to the guidelines. Those who underwent immediate LP without CT received antibiotics 1.6 hours earlier than those who underwent CT prior to LP. Treatment delay resulted in a significantly increased risk of fatal outcome, with a relative increase in mortality of 13 percent per hour of delay.

If LP is delayed — If LP is delayed or deferred, blood cultures should be obtained and antimicrobial therapy should be administered empirically before the imaging study, followed as soon as possible by the LP. In addition, dexamethasone(0.15 mg/kg intravenously [IV] every six hours) should be given shortly before or at the same time as the antimicrobial agents if the preponderance of clinical and laboratory evidence suggests bacterial meningitis with a plan to stop therapy, if indicated, when the evaluation is complete. Adjunctive dexamethasone should not be given to patients who have already received antimicrobial therapy because it is unlikely to improve patient outcome [29]. (See "Dexamethasone to prevent neurologic complications of bacterial meningitis in adults" and "Initial therapy and prognosis of bacterial meningitis in adults", section on 'Avoidance of delay'.)

Prior administration of antimicrobials tends to have minimal effects on the chemistry and cytology findings [24,32] but can reduce the yield of Gram stain and culture [23-25]. However, a pathogen can still be cultured from the CSF in most patients up to several hours after the administration of antimicrobial agents [24,25], with the possible exception of the meningococcus. This issue was addressed in a review of 128 children with bacterial meningitis in whom LP was first performed after initiation of therapy and serial LPs were obtained [25]. Among patients with meningococcal infection, CSF culture was negative in three of nine samples obtained within one hour. In contrast, 4 to 10 hours were required before CSF cultures were sterile in patients with pneumococcal meningitis.

Relative contraindications — Although there are no absolute contraindications to performing an LP, caution should be used in patients with evidence of raised intracranial pressure (eg, mass effect on CNS imaging or clinical signs of impending herniation), thrombocytopenia or another bleeding diathesis, or spinal epidural abscess. (See "Lumbar puncture: Technique, indications, contraindications, and complications in adults".)

Opening pressure — The opening pressure is typically elevated in patients with bacterial meningitis. In the series of 301 adults cited above, the mean opening pressure was approximately 350 mm H2O (normal up to 200 mm H2O) [2]. However, there is a wide range of values as illustrated in a report of 296 episodes of community-acquired bacterial meningitis: 39 percent had values ≥300 mm H2O, while 9 percent had values below 140 mm H2O [3].

The opening pressure with the patient lying in the lateral decubitus position should be measured and documented.

It is important to know the specific cause of meningitis because the treatment differs depending on the cause.

 

 

TWO TYPES OF MENINGOCOCCAL MENINGITIS VACCINES FOR TEENS AND YOUNG ADULTS

Meningitis ACWY vaccines have been available since the 1980s, but Meningitis B vaccines have been available in the US only since late 2014.

The CDC recommends Meningitis B vaccination for persons 10 years and older in certain groups who are at increased risk for Meningitis B disease. In addition, the CDC says that Meningitis B vaccines may be administered to young adults who are 16–23 years old, but preferably to those who are 16–18 years old.


although vaccines may not result in protection in all recipients. Vaccination does not prevent viral meningitis.

In addition to vaccinating, you can take the following steps to help protect against meningococcal meningitis:

Practice good hygiene

 

Who's at risk?

Anyone can get meningococcal meningitis—however, certain people face a higher risk:

Infants younger than 1

16–23 year-olds

People with weakened immune systems

People without a spleen

Travelers to areas where meningococcal disease is more common

 

Survivors can experience a number of long-term disabilities, including:

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Brain damage

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Hearing loss

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Loss of limbs

 

 

The mortality rate of untreated bacterial meningitis approaches 100 percent and, even with optimal therapy, morbidity and mortality may occur. Neurologic sequelae are common among survivors.

Despite the effectiveness of current antibiotics in clearing bacteria from the cerebrospinal fluid (CSF), bacterial meningitis continues to cause significant morbidity and mortality worldwide. In two large case series, for example, the case-fatality rate for adults with bacterial meningitis was approximately 25 percent, and transient or permanent neurologic morbidity occurred in 21 to 28 percent of survivors [2,3].

 

 

 Unfavorable neurologic outcomes are not the result of treatment with inappropriate antimicrobial agents, since cerebrospinal fluid cultures are sterile 24 to 48 hours after the start of antibiotic therapy.3 Studies in animals have shown that bacterial lysis, induced by treatment with antibiotics, leads to inflammation in the subarachnoid space, which may contribute to an unfavorable outcome.4,5 These studies also show that adjuvant treatment with antiinflammatory agents, such as dexamethasone, reduces both cerebrospinal fluid inflammation and neurologic sequelae.4,5

Content 13

Content 11

A 3-year-old girl was brought to the emergency room by her parents because of fever and loss of appetite for the past 24 hours and difficulty in arousing her for the past 2 hours. The developmental history had been normal since birth. She attended a day care center and had a history of several episodes of presumed viral infections similar to those of other children at the center. Her childhood immunizations were current.

Temperature was 39.5°C, pulse 130/min, and respirations 24/min. Blood pressure was 110/60 mm Hg.

Physical examination showed a well-developed and well-nourished child of normal height and weight who was somnolent. When her neck was passively flexed, her legs also flexed (positive Brudzinski sign, suggesting irritation of the meninges).

Ophthalmoscopic examination showed no papilledema, indicating that there had been no long-term increase in intracranial pressure. The remainder of her physical examination was normal.

Laboratory Findings

Minutes later, blood was obtained for culture and other laboratory tests, and an intravenous line was placed. Lumbar puncture was performed less than 30 minutes after the patient arrived in the emergency room. The opening pressure was 350 mm of cerebrospinal fluid (CSF) (elevated). The fluid was cloudy. Several tubes of CSF were collected for culture, cell counts, and chemistry tests. One tube was taken immediately to the laboratory for Gram staining. The stain showed many polymorphonuclear (PMN) cells with cell-associated (intracellular) gram-negative diplococci suggestive of Neisseria meningitidis.

Blood chemistry tests were normal. The hematocrit was normal. The white blood cell count was 25,000/μL (markedly elevated), with 88% PMN forms and an absolute PMN count of 22,000/μL (markedly elevated), 6% lymphocytes, and 6% monocytes. The CSF had 5000 PMNs/μL (normal, 0–5 lymphocytes/μL). The CSF protein was 100 mg/dL (elevated), and the glucose was 15 mg/dL (low, termed hypoglycorrhachia)—all consistent with bacterial meningitis. Cultures of blood and CSF grew serogroup B N meningitidis.

 

A 19-year-old man is brought to the emergency department (ED) by his roommate, who states that the patient has “not been acting right” for the past 24 hours.

Per the roommate, the patient had complained of a headache 2 days prior to arrival and has been progressively somnolent and confused since then. The patient has no past medical history and does not take any medications. His roommate states that the patient is a college student who does not use any illegal drugs and occasionally drinks alcohol. Review of systems is positive for headache and altered mental status as stated above, as well as a tactile fever for the past 2 days. Additional review of systems is unobtainable, as the patient is unable to answer any questions. On physical examination the patient is noted to be febrile to 38.5°C (101°F) orally, with a heart rate of 120 beats per minute, blood pressure of 114/69 mm Hg, and respiratory rate of 20 breaths per minute. His oxygen saturation is 98% on room air. The head and neck examination are significant for dry mucous membranes and nuchal rigidity. His cardiopulmonary examination is within normal limits, with the exception of tachycardia. The abdomen is soft and nontender. His skin is noted to be warm and well perfused without any rash. The neurologic examination is significant for an altered mental status with a Glasgow coma score (GCS) of 10 (eyes open to voice [3], patient moans to painful stimuli [2], and localizes painful stimuli [5]). The motor examination is symmetric, and the patient appears to be sensate in all extremities. His reflexes are 2+ bilaterally throughout the upper and lower extremities with downgoing toes. Laboratory studies reveal a leukocytosis of 24,000/mm3 with a left shift and are otherwise unremarkable. A CT scan is completed which shows no mass, shift, bleed, or edema.

Content 3

 

An 82-year-old man is brought to the emergency department by his daughter. He has had an increasingly severe headache, plus nausea and vomiting, for the past 2 days. The daughter reports that this morning he was difficult to rouse and that he has not seen a doctor in "years" because he has been very healthy. He has no drug allergies. The patient is originally from Mexico but has been in the United States for more than 30 years. On examination, he is lethargic, with neck stiffness and a temperature of 38.9°C.
After receiving empiric ceftriaxone and vancomycin, he undergoes an urgent lumbar puncture. Examination of the cerebrospinal fluid reveals a leukocyte count of 1300 per mm3 (75% neutrophils and 25% lymphocytes), a protein level of 110 mg/dL (reference range, 15–45), and a glucose level of 50 mg/dL (40–70). Serum glucose is within normal limits. Gram's stain of cerebrospinal fluid reveals what appear to be small gram-positive rods.

Which one of the following antimicrobial treatments should be added to this patient's treatment?

» Rifampin
» Ampicillin plus gentamicin
» Acyclovir
» Chloramphenicol
» Trimethoprim–sulfamethoxazole

 

RifampinAmpicillin plus gentamicinAcyclovirChloramphenicolTrimethoprim–sulfamethoxazole

Key Learning Point View Case Presentation

The antimicrobial treatment of choice for bacterial meningitis that is due to Listeria monocytogenes is ampicillin plus gentamicin.

Detailed Feedback

Listeria monocytogenes, a gram-positive rod, is a foodborne pathogen with a tropism for the central nervous system. L. monocytogenes outbreaks have been associated with unpasteurized milk, soft cheeses, and deli-style meats. Illness, though rare in the general population, is an important cause of disease in newborns, pregnant women, the elderly, and people with impaired, cell-mediated immunity, such as transplant recipients and patients with AIDS. In 1995, the Centers for Disease Control and Prevention reported that L. monocytogenes accounted for 20% of bacterial meningitis cases among people >60 years of age. Presentation may be more subacute (>24 hours) than it is with other forms of bacterial meningitis. Cerebrospinal fluid Gram’s stain may be positive in only 30% to 40% of cases.

Pregnant women are also at increased risk for listeria infection. In this population, it causes chorioamnionitis in the woman (not meningitis), which at the time of delivery can lead to neonatal meningitis. Because of this risk, pregnant women are advised to avoid foods that may be sources of listeria infection, such as soft cheeses and deli meats.

In adults with suspected bacterial meningitis, empiric ceftriaxone and vancomycin should be administered immediately to cover the most common etiologic agents. Empiric addition of ampicillin is recommended for treatment of bacterial meningitis in people >50 years of age. Ampicillin or penicillin is the preferred agent for treating L. monocytogenes infections. Synergy with aminoglycosides, such as gentamicin, has been demonstrated in vitro, and these agents are often used in conjunction with penicillins in treating Listeria meningitis.

Trimethoprim–sulfamethoxazole is the treatment of choice for a patient with a penicillin allergy.

Cephalosporins have limited activity against L. monocytogenes, and high reported rates of failure have been associated with chloramphenicol and rifampin.

Acyclovir is an antiviral agent with no activity against bacteria.

Last reviewed Nov 2016. Last modified Nov 2016.

Citations

van de Beek D et al. Community-acquired bacterial meningitis in adults. N Engl J Med 2006 Jan 6; 354:44. > View Abstract

Clauss HE and Lorber B. Central nervous system infection with Listeria monocytogenes. Curr Infect Dis Rep 2008 Sep 4; 10:300.   > View Abstract

Tunkel AR et al. Practice guidelines for the management of bacterial meningitis. Clin Infect Dis 2004 Nov 1; 39:1267.   > View Abstract

4 Comments

  1. Surapee P. December 27, 2016 at 2:09 am - Reply  >

    My answer on day 27 Dec. is incorrect.An 82-year-old man with meningitis received ceftriaxone and vancomycin and the answer of antibiotic should add to this patient is ampicillin plus gentamicin I think why use this old and common medication to this case and a gram-positive rod pathogen of this case is Listeria monocytogenes.What is the Gram-Positive rod Bacteria.

  2. 261103 December 27, 2016 at 3:10 am - Reply  >

    I have turned on the light.

  3. Conor T McCartney December 27, 2016 at 11:17 am - Reply  >

    another week, another great question

  4. Jonathan C Weissler December 27, 2016 at 11:19 am - Reply  >

    Could also be Nocardia, which is a gram positive rod. Bactrim would cover both Nocardia and Listeria.

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All of the following are predisposing conditions that increase the risk for development of acute bacterial meningitis due to S pneumoniae EXCEPT:

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The correct answer is D.

The answer is D.  S pneumoniae is the most common cause of meningitis in adults >20 years of age, accounting for nearly half the reported cases (1.1 per 100,000 persons per year). There are a number of predisposing conditions that increase the risk of pneumococcal meningitis, the most important of which is pneumococcal pneumonia. Additional risk factors include coexisting acute or chronic pneumococcal sinusitis or otitis media, alcoholism, diabetes, splenectomy, hypogammaglobulinemia, complement deficiency, and head trauma with basilar skull fracture and cerebrospinal fluid (CSF) rhinorrhea. The mortality rate remains ~20% despite antibiotic therapy. Pregnancy, age >60 years, and immunocompromised status are important risk factors for meningitis due to Listeria monocytogenes.

 

A 42-year-old woman presents to the emergency department with a 1-day history of fever, neck stiffness, and a severe headache. Her examination reveals a widespread maculopapular rash. Which of the following is the most appropriate next step in management?

Obtain a STAT CT scan of the head followed by an LP.

Perform a STAT LP without obtaining a CT scan of the head.

Obtain a CBC with differential, blood cultures, chemistry 20, and INR, and begin IV penicillin G or ampicillin.

Obtain a CBC with D-P, blood cultures, chemistry 20, and INR, and begin IV ceftriaxone plus vancomycin.

The correct answer is C.

C. The presence of maculopapular rash should cause the clinician to strongly suspect meningococcal meningitis in the patient. Because of the high morbidity and mortality with meningococcal meningitis, treatment should be started immediately. Until Gram stain and culture results are available, penicillin G and/or ampicillin should be started empirically. Serologic studies including blood cultures are necessary prior to starting antibiotics in case there is a delay in obtaining an imaging study.

28% of users answered correctly.

 

A 2-year-old girl she develops irritability, vomiting, low-grade fever, and frontal headache over 2 days.

Physical examination reveals only a stiff neck, wherein the patient resists attempts to flex it.

A lumbar puncture is done to quickly rule out bacterial meningitis. The CSF results are 90 cells/mm3, 70% mononuclears, glucose 60 mg/dL, and protein 45 mg/dL. Gram stain is negative for bacteria.

 

Which of the following tests would be most sensitive and specific at this stage of illness?

IgM-specific serology on CSF

Viral culture of CSF

RT-PCR on CSF

RT-PCR on rectal swab specimen

IgM-specific serology on serum

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The correct answer is C. You answered C.

1. (C)

 

A 19-year-old college student presents to the emergency department with fever, headache, myalgias, and confusion. She has had a splenectomy but is otherwise healthy. The examination is notable for somnolence, fever, and nuchal rigidity. Due to her inability to follow directions, the neurological examination is difficult to complete, but it appears to be non-focal. There are several other seriously ill patients in the ED to triage. Which of the following interventions should not wait an hour and must be done now?

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The correct answer is A. You answered A.

The correct answer is "A." This patient likely has meningitis. Accordingly, treatment must be started within the first hour regardless of your ability to get a CT scan, perform an LP, or get blood cultures. Sure, those would be nice. But don't delay treatment. You might also consider acyclovir to cover for encephalitis (though with the stiff neck, etc. it is more likely meningitis). "B" is of special mention. So what is the big deal with neurosurgery? All you need is a saw, a spoon, and a couple of those hair clips to prevent bleeding…. 

 

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