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Bacterial Meningitis Overview
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Bacterial Meningitis Overview
Bacterial Meningitis Overview
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1
Question
What is the definition of Acute Bacterial Meningitis?
Answer
It is an acute purulent infection within the subarachnoid space. The meninges, the subarachnoid space, and the brain parenchyma are all frequently involved in the inflammatory reaction meningoencephalitis.
2
Question
What is the epidemiology of bacterial meningitis in the United States?
Answer
Bacterial meningitis is the most common form of suppurative CNS infection, with an annual incidence of 2.5 cases per 100,000 population.
3
Question
What organisms are most commonly responsible for community-acquired bacterial meningitis?
Answer
The organisms most commonly responsible are: 1. Streptococcus pneumoniae (50%) 2. Neisseria meningitidis (25%) 3. Group B streptococci (15%) 4. Listeria monocytogenes (10%) 5. Haemophilus influenzae (10%)
4
Question
What organism is most commonly responsible for hospital-acquired meningitis?
Answer
Pseudomonas aeruginosa is the most common organism responsible for hospital-acquired meningitis.
5
Question
What are some predisposing conditions for pneumococcal meningitis?
Answer
Predisposing conditions include: 1. Pneumococcal pneumonia 2. Acute or chronic pneumococcal sinusitis or otitis media 3. Alcoholism 4. Diabetes 5. Splenectomy 6. Hypogammaglobulinemia 7. Complement deficiency 8. Head trauma with basilar skull fracture and CSF rhinorrhea.
6
Question
What are significant clinical features of bacterial meningitis?
Answer
The classic clinical triad of meningitis includes: 1. Fever 2. Headache 3. Nuchal rigidity. This triad occurs in 90% of cases. Alteration in mental status occurs in 75% of patients, ranging from lethargy to coma.
7
Question
What is Kernig's sign?
Answer
Kernig's sign is a clinical indicator of meningitis, characterized by resistance to leg straightening when the hip is flexed.
8
Question
What are common complications of bacterial meningitis?
Answer
Raised intracranial pressure (ICP) is an expected complication, leading to papilledema, 6th cranial nerve palsy, decerebration, and herniation.
9
Question
What should be done when bacterial meningitis is suspected?
Answer
When bacterial meningitis is suspected, blood cultures should be immediately obtained and then empirical antimicrobial therapy should be initiated without delay.
10
Question
What are the CSF abnormalities in bacterial meningitis?
Answer
Cerebrospinal fluid (CSF) abnormalities include: 1. Appearance: purulent 2. Opening pressure: 180 mmH2O 3. White blood cells: 10L to 10,000L (neutrophils predominate) 4. Red blood cells: Absent in non-traumatic tap 5. Glucose: 2.2 mmol/L (40 mg/dL) 6. CSF serum glucose ratio: 0.6 7. Protein: 0.45 g/L (45 mg/dL) 8. Gram stain: Positive in 60% 9. Culture: Positive in 80%.
11
Question
What are indications for a CT brain scan before a lumbar puncture?
Answer
Indications for CT brain scan before lumbar puncture include: 1. Papilledema 2. Focal or generalized seizures 3. Known case of brain tumor or systemic cancer 4. Immune deficiency 5. Focal neurological signs 6. Impaired consciousness.
12
Question
What are the differential diagnoses for bacterial meningitis?
Answer
Differential diagnoses include: 1. Viral meningitis 2. Viral encephalitis 3. Rocky Mountain spotted fever (RMSF) 4. Subdural and epidural empyema and brain abscess 5. Subarachnoid hemorrhage 6. Chemical meningitis 7. Carcinomatous or lymphomatous meningitis 8. Meningitis associated with inflammatory non-infectious disorders 9. Superior sagittal sinus thrombosis 10. ADEM.
13
Question
What is the empirical treatment for bacterial meningitis in preterm infants?
Answer
Empirical treatment for preterm infants (infants during the 1st month of life) includes Ampicillin and Cefotaxime.
14
Question
What is the empirical treatment for bacterial meningitis in children from 2 to 3 months of age?
Answer
Empirical treatment for infants from 2 to 3 months of age includes Ampicillin and Cefotaxime or Ceftriaxone.
15
Question
What is the empirical treatment for bacterial meningitis in adults 55 years and older?
Answer
Empirical treatment for adults 55 years and older, especially those with alcoholism or other debilitating illnesses, includes Ampicillin 2g x 4, Cefotaxime 2g x 4 or Ceftriaxone 2g x 2, and Vancomycin 1g x 2.
16
Question
What is the specific treatment for Neisseria meningitidis?
Answer
For Neisseria meningitidis, treatment duration is 1 week: Penicillin-sensitive strains receive Penicillin G or Ampicillin, while Penicillin-resistant strains receive Ceftriaxone or Cefotaxime.
17
Question
What is the prognosis for bacterial meningitis caused by Listeria monocytogenes?
Answer
Mortality for bacterial meningitis caused by Listeria monocytogenes is approximately 15%.
18
Question
What are bad prognostic signs in bacterial meningitis?
Answer
Bad prognostic signs include: 1. Decreased level of consciousness on admission 2. Onset of seizures within 24 hrs of admission 3. Signs of increased ICP 4. Young age (infancy) and age 50 or more 5. Presence of co-morbid conditions including shock or the need for mechanical ventilation 6. Delay in the initiation of treatment 7. Decreased CSF glucose concentration 2.2 mmol/L (40 mg/dL) 8. Markedly increased CSF protein concentration 3 g/L (300 mg/dL).