Bacterial meningitis
From IDWiki
Background
- Bacterial infection of meninges and subarachnoid space (i.e. meningitis)
Microbiology
- Adults 1
- Streptococcus pneumoniae (70%)
- Neisseria meningitidis (15%): more in young adults
- Group B Streptococcus (10%)
- Haemophilus influenzae (10%)
- Listeria monocytogenes (5%): more in elderly ≥65 years, immunocompromised, alcoholics, and diabetes
- Infants ≤2 months old 1
- Group B Streptococcus (90%)
- Listeria monocytogenes, Streptococcus pneumoniae, others including Gram-negative bacilli
- Infants 2 months to 2 years 1
- Streptococcus pneumoniae (50%)
- Group B Streptococcus (20%)
- Neisseria meningitidis (15%)
- Haemophilus influenzae (10%)
- Neurosurgery
- Basal skull fracture
- Asplenia
- Relatively immunocompromised (alcohol use disorder, diabetes, malignancy, chemotherapy)
- Strongyloides hyperinfection
- Gut flora
Risk factors
- Immunosuppression
- Diabetes
- Hyposplenism or splenectomy (e.g. sickle cell)
- Alcohol use disorder
- Recent neurosurgery
- CSF leak
- Ventricular shunt infection
- Head trauma
- Chronic otitis media
Clinical Manifestations
- Typically, an acute onset of headache, neck stiffness, fever, and photophobia
- Headache or neck pain (70-80%)
- Fever (75%)
- Altered level of consciousness (70%)
- Clinical signs
- Brudzinski's sign (unhelpful)
- Kernig's sign (may be specific)
- Jolt test (very sensitive)
- Seizures or focal neurological deficits (rare, poor prognosis)
- Rash (petechial or purpuric with Neisseria)
- Ask about recent travel and sick contacts
Investigations
- Lumbar puncture after CT head (if needed), sent for Gram stain, culture, viral PCR, cell count with differential, protein, ± cryptococcal antigen, ± fungal cultures
- Lab
- CBC with differential
- Electrolytes
- Liver enzymes
- Blood cultures
- Imaging
- CT head to rule out abscess or increased ICP
- MRI head if suspicion for herpes encephalitis
- Temporal lobe enhancement (usually unilateral)
CSF Interpretation
- Gram stain positive
- Glucose <1.0
- CSF:blood glucose <0.23
- Protein >2.2
- WBC >2000
- PMNs >1180
Management
- Blood cultures before antibiotics, if possible
- Start empiric antibiotics and dexamethasone
- Infants
- Children
- Adults
- Ceftriaxone 2g bid plus vancomycin 1g q12h +/- ampicillin 2g 14h if >50
- Dexamethasone 10mg q6h x72h (stopped if not Streptococcus pneumoniae or Haemophilus influenzae)
- Prevents severe hearing loss, neurologic sequelae, and mortality in pneumococcal meningitis
- Continue for 3-4 days
- Consider empiric acyclovir, as well, until confirmed to be bacterial
- >65 years old
- Treat like immunocompromised
- CT head if reduced or altered level of consciousness
- Lumbar puncture
- Adjust antibiotics based on Gram stain and cultures
Antimicrobials By Organism
| Organism | First-line | Second-line | Duration |
|---|---|---|---|
| Streptococcus pneumoniae (penicillin MIC ≤0.06) | penicillin G or ampicillin | third-generation cephalosporin or chloramphenicol | 10-14 days |
| Streptococcus pneumoniae (penicillin MIC ≥0.12) | third-generation cephalosporin | cefipime or meropenem | |
| Streptococcus pneumoniae (ceftriaxone MIC ≥1) | vancomycin plus a third-generation cephalosporin | fluoroquinolone | |
| Neisseria meningitidis (penicillin MIC ≤0.06) | penicillin G or ampicillin | third-generation cephalosporin or chloramphenicol | 7 days |
| Neisseria meningitidis (penicillin MIC ≥0.12) | third-generation cephalosporin | chloramphenicol, fluoroquinolone, or meropenem | |
| Listeria monocytogenes | ampicillin or penicillin G | TMP-SMX or meropenem | ≥21 days |
| Streptococcus agalactiae | ampicillin or penicillin G | third-generation cephalosporin | 14-21 days |
| E. coli and other Enterobacteriaceae | third-generation cephalosporin | ampicillin, meropenem, aztreonam, TMP-SMX, or ciprofloxacin | 21 days |
| Pseudomonas aeruginosa | cefipime or ceftazidime | meropenem, aztreonam, or ciprofloxacin | |
| ESBL Gram-negative bacillus | meropenem | cefepime or a fluoroquinolone | |
| Haemophilus influenzae (β-lactamase negative) | ampicillin | third-generation cephalosporin, cefepime, chloramphenicol, or a fluoroquinolone | 7 days |
| Haemophilus influenzae (β-lactamase positive) | third-generation cephalosporin | cefepime, chloramphenicol, or a fluoroquinolone | |
| Staphylococcus aureus (methicillin-susceptible) | nafcillin or oxacillin | vancomycin | |
| Staphylococcus aureus (methicillin-resistant) | vancomycin | daptomycin, TMP-SMX, or linezolid | |
| Staphylococcus epidermidis | vancomycin | linezolid | |
| Enterococcus species (ampicillin susceptible) | ampicillin plus gentamicin | ||
| Enterococcus species (ampicillin resistant) | vancomycin plus gentamicin | ||
| Enterococcus species (ampicillin and vancomycin resistant) | linezolid | ||
| No organism identified | ceftriaxone | 10 days |
Antimicrobial Dosages
| Antimicrobial | Neonate (≤7 days) | Neonate (8 to 28 days) | Infants and children | Adults |
|---|---|---|---|---|
| amikacin | 15-20 mg/kg divided q12h | 30 mg/kg divided q8h | 20-30 mg/kg divided q8h | 15 mg/kg divided q8h |
| ampicillin | 150 mg/kg divided q8h | 200 mg/kg divided q6-8h | 300 mg/kg divided q6h | 12 g divided q4h |
| aztreonam | 6-8 g divided q6-8g) | |||
| cefepime | 150 mg/kg divided q8h | 6 g divided q8h | ||
| cefotaxime | 100-150 mg/kg divided q8-12h | 150-200 mg/kg divided q6-8h | 225-300 mg/kg divided q6-8h | 8-12 g divided q4-6h |
| ceftazidime | 100-150 mg/kg divided q8-12h | 150 mg/kg divided q8h | 150 mg/kg divided q8h | 6 g divided q8h |
| ceftriaxone | 80-100 mg/kg divided q12-24h | 4 g divided q12-24h | ||
| chloramphenicol | 25 mg/kg divided q24h | 50 mg/kg divided q12-24h | 75-100 mg/kg divided q6h | 4-6 g divided q6h |
| ciprofloxacin | 800-1200 mg divided q8-12h | |||
| gatifloxacin | 400 mg divided q24h | |||
| gentamicin | 5 mg/kg divided q12h | 7.5 mg/kg divided q8h | 7.5 mg/kg divided q8h | 5 mg/kg divided q8h |
| meropenem | 120 mg/kg divided q8h | 6 g divided q8h | ||
| moxifloxacin | 400 mg divided q24h | |||
| nafcillin | 75 mg/kg divided q8-12h | 100-150 mg/kg divided q6-8h | 200 mg/kg divided q6h | 9-12 g divided q4h |
| oxacillin | 75 mg/kg divided q8-12h | 150-200 mg/kg divided q6-8h | 200 mg/kg divided q6h | 9-12 g divided q4h |
| penicillin G | 0.15 mU/kg divided q8-12h | 0.2 mU/kg divided q6-8h | 0.3 mU/kg divided q4-6h | 24 mU divided q4h |
| rifampin | 10-20 mg/kg divided q12h | 10-20 mg/kg divided q12-24h | 600 mg divided q24h | |
| tobramycin | 5 mg/kg divided q12h | 7.5 mg/kg divided q8h | 7.5 mg/kg divided q8h | 5 mg/kg divided q8h |
| TMP-SMX | 10-20 mg/kg divided q6-12h | 10-20 mg/kg divided q6-12h | ||
| vancomycin | 20-30 mg/kg divided q8-12h | 30-45 mg/kg divided q6-8h | 60 mg/kg divided q6h | 30-45 mg/kg divided q8-12h |
Complications
- Cerebral edema with raised ICP
- Hydrocephalus
- Seizures
- Arterial ischemia or infarction
- SIADH
- Subdural effusion or subdural empyema
- Venous sinus thrombosis
- Cranial nerve palsies, especially deafness
References
- a b c Michael C. Thigpen, Cynthia G. Whitney, Nancy E. Messonnier, Elizabeth R. Zell, Ruth Lynfield, James L. Hadler, Lee H. Harrison, Monica M. Farley, Arthur Reingold, Nancy M. Bennett, Allen S. Craig, William Schaffner, Ann Thomas, Melissa M. Lewis, Elaine Scallan, Anne Schuchat. Bacterial Meningitis in the United States, 1998–2007. New England Journal of Medicine. 2011;364(21):2016-2025. doi:10.1056/nejmoa1005384.
