|
| |
| Bacterial meningitis |
Early treatment
 | Start treatment as early as possible. |
| Get Blood cultures before giving antibiotic, positive in
60%. |
| Get CT head before LP if patient has decreased level of
consciousness, papilledema, prolonged seizures or focal deficit. |
| Duration of Airborne precautions: 24 hours after effective
antibiotic therapy. |
|
Steroid treatment
| Dexamethasone therapy
 | 0.15 mg/kg IV every 6 hours for 4 days is recommended for children older
than 2 months of age who have not been vaccinated for H. influenze type b (Hib) and
for those with Gram-negative coccobacilli on a Gram's stain of CSF. |
| Reduced audiologic and neurologic sequelae when administered before antibiotics.
These children primarily were infected with H. influenze type b (Hib). |
| There is only 1 prospective study done for adults,
seems to suggest similar efficacy. |
|
| Quagliarello and Scheld have suggested that adults with a high concentration of
bacteria in their CSF (as demonstrated with a positive Gram's stain) and evidence of
raised intracranial pressure should receive the same 4-day regimen of steroid beginning 20
minutes before the first antibiotic dose. |
|
Epidemiology
| The frequency of meningitis caused by Haemophilus
influenzae has declined by 82% owing to the introduction of vaccination. |
| Most common community-acquired meningitis in adults in N
America:
| S. pneumoniae: 38% |
| N. meningitidis: second most common 15 - 40% |
| Followed by: H influenzae, Listeria monocytogenes |
|
| Case-fatality rates:
| S pneumoniae: around 20%. |
| N meningitidis: 5% to 10% |
| H influenzae type b: 3% to 6% |
|
| Increase in antibiotic-resistant strains of S. pneumoniae:
In 1994, 25% of the isolates from patients who had pneumococcal infection were resistant
to penicillin and 9% were resistant to cefotaxime. |
|
Clinical symptoms
| Classic triad: fever, nuchal rigidity and altered mental
status was present in only two thirds of community-acquired bacterial meningitis cases in
one series, but all had at least one of these findings. |
| 25% of patients develop seizure during hospitalization. |
| Focal findings were present in 28% and may be caused by
cortical vein thrombosis, cerebral artery spasm, subdural empyema, or abscess. |
|
CSF findings
| WBC 50 to 10,000: Predominantly neutrophils |
| Glucose < 40 in half of the cases |
| Bacterial antigen
| available for limited types of bacteria: S
pneumoniae, N meningitidis, H influenzae type b and group B streptococcus |
| false positive do occur |
| no more sensitive than gram stain |
| may be helpful with partially treated meningitis |
| negative result for a specific bacterial antigen does not rule out bacterial
meningitis |
|
| In untreated bacterial meningitis
| CSF Gram stains reveal bacteria in about 50% to 80% |
| Cultures are positive > 85% of cases |
| Sensitivity of both tests decreases to less than 50% in patients already taking
antibiotics |
|
| Other tests
| Elevation of the concentration of C-reactive protein in CSF is highly sensitive
for bacterial meningitis but is not specific. |
|
|
Initial choice of antibiotics
| Community acquired, immunocompetent Adults
| Ceftriaxone (Rocephin) 2 g iv q12 |
| consider adding Vancomycin 1 g iv q12 to cover resistant S
pneumonia depending on community. Monitor renal function. |
| If allergic to penicillin, use Chloramphenicol 1 g iv q6 |
|
| Community acquired, elderly or immunosuppressed
| Ceftriaxone (Rocephin) 2 g iv q12 PLUS Ampicillin 2 g
iv q4 to cover Listeria |
| Consider adding Vancomycin 1 g iv q12 to cover resistant S
pneumonia if indicated, monitor renal function. |
| If allergic to penicillin, consider Ceftriaxone plus
TMP/SMX, (Septra) 20 ml (80/400/5ml) iv q8 |
|
|
Nondiagnostic Gram Stain
| 18-50
years old |
Cerftriaxone +/-
Vancomycin |
| <50
years old |
Cerftriaxone/Cefotaxime
plus Ampicillin or Penicillin |
| Head trauma,
neurosurgery, CSF shunt |
Vancomycin +
Ceftazidime |
| Impaired cellular
immunity |
Ampicillin +
Ceftazidime |
|
Positive Gram Stain
| Cocci, Gram
positive |
Vancomycin +
Ceftriaxone |
| Cocci, Gram
negative |
Penicillin G |
| Bacilli, Gram
positive |
Ampicillin or
Penicillin G plus aminoglycoside |
| Bacilli, Gram
negative |
Ceftazidime |
|
Risk Factors
| Pneumococcus
| Alcoholism, Splenectomy, Sickle Cell anemia, Sinus disease
or Basilar skull fracture |
|
| Staphylococcus
| Trauma, indwelling shunt, Intracranial surgery |
|
| Listeria
| elderly, debilitated |
|
|
Specific treatment for known organism
| Hemophilus influenzae
| Ceftriaxone 1-2 g iv q12 |
| For contacts: if less than 6 years of age and not
previously vaccinated, Rifampin 10mg/kg bid for 4 days |
|
| Listeria monocytogenes
| Ampicillin 2 g iv q4 |
|
| Nisseria menintitidis
| Penicillin G 24 million units continuous drip q 24 hour |
| For contacts: Sulfadiazine 500 mg bid for 3 days
or Rifampin 600 mg for 2 days |
|
| Gram negative bacilli
| Ceftriaxone 1-2 g iv q12 and Gentamicin 3-5 mg/kg/day in 3
divided dose, monitor renal function |
|
| Pseudomonas:
| Ceftazidime (Fortaz) 2 g iv q8 |
| Gentamicin 3-5 mg/kg/day in 3 divided dose, monitor
renal function |
|
| Staphylococcal:
| Nafcillin 2 g iv q4 |
| If MRSA likely: Vancomycin 1 g iv q 12, plus Gentamicin 2-5
mg/kg/day iv in 3 divided doses |
|
|
Shunt associated CNS infections
| Most shunt infections take place soon after shunt placement
or revision, with 70% occurring within 2 months of the last surgical procedure. |
| Diagnosis is based on recurrence of hydrocephalic symptoms,
abdominal distension after ventriculoperitoneal infection, fever, and a positive CSF
culture or culture from shunt components. |
| A difficult problem is the presence of positive cultures of
shunt hardware removed electively at the time of surgery in the absence of evidence of CSF
infection. At times, these shunt colonizations may be considered asymptomatic. |
| Most common causative organisms are Staphylococcus
epidermidis and Staphylococcus aureus. Intravenous antibiotics, shunt removal, and
immediate or delayed replacement of shunt components results in excellent cure rates. |
| Vancomycin 1 g iv q12 plus Ceftriaxone 1 to 2 g iv q12 |
| Consider intraventricular antibiotics. |
|
Complications of Meningitis
| Immediate complications
| seizures, raised intracranial pressure, cerebral venous thrombosis, sagittal
sinus thrombosis, and hydrocephalus. |
|
| Weeks to months after bacteriologic cure,:communicating hydrocephalus may present
with gait difficulty, mental status changes, and incontinence. |
|
| Differential Dx of Fever, Altered Sensorium,
and Petechia: |
| Meningococcal disease
| Examination of petechiae, by scrapings with a touch preparation technique
and proper staining may detect meningococci in 70% of cases. |
| The organism may be seen on peripheral blood smear, especially a buffy
coat preparation. |
|
| Rickettsial infections (Rocky Mountain spotted fever) |
| Staph aureus endocarditis |
| S pneumoniae, H influenzae infection |
| Septic shock |
| Viral meningitis |
| Viral hemorrhagic fevers |
| Thrombotic thrombocytopenic purpura, hemolytic-uremic syndrome, vasculitis etc.
|
|
| References & Further
reading |
|
|
Neuro infection info center
|
