Bacterial Meningitis

Bacterial meningitis
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Bacterial meningitis
The most common form of suppurative CNS infection (purulent) and occurs within the subarachnoid space
-decreased consciousness
-seizures
-raised intracranial pressure (ICP)
-stroke
Bacterial meningitis is associated with a CNS inflammatory reaction that may result in what?
-meninges
-SAS
-brain parenchyma
What parts of the brain are frequently involved in the inflammatory reaction (meningoencephalitis)?
-Streptococcus pneumoniae (~50%)
-Neisseria meningitidis (~25%)
-group B streptococci (~15%)
-Listeria monocytogenes (~10%).
What are the organisms most often responsible for community-acquired bacterial meningitis?
N. meningitidis
What is the causative organism of recurring epidemics of meningitis every 8-12 years?
Haemophilus influenzae type b
What organism accounts for <10% of cases of bacterial meningitis in most series?
pneumococcal pneumonia
What are the the most important predisposing conditions that increase the risk of pneumococcal meningitis?
-coexisting acute or chronic pneumococcal sinusitis or otitis media
-alcoholism
-diabetes
-splenectomy
-hypogammaglobulinemia
-complement deficiency
-head trauma with basilar skull fracture and CSF rhinorrhea
Other predisposing conditions that increase the risk of pneumococcal meningitis include what?
True
True or False: The mortality rate for bacterial meningitis remains ~20% despite antibiotic therapy
petechial or purpuric skin lesions
The presence of what clinical finding can provide an important clue to the diagnosis of meningococcal infection?
Gram-negative bacilliWhat organism can cause meningitis in individuals with chronic and debilitating diseases (diabetes, cirrhosis, or alcoholism, chronic urinary tract infections) and in neuro sx patients?-Streptococci sp. -gram-negative anaerobes -Staphylococcus aureus -Haemophilus sp. -EnterobacteriaceaeOtitis, mastoiditis, and sinusitis are predisposing and associated conditions for meningitis due to what pathogens?Group B StreptococcusWhat organism was previously responsible for meningitis predominantly in neonates, but it has been reported with increasing frequency in individuals aged >50 years, particularly those with underlying diseases?H. influenzae type b (Hib)The frequency of ________ meningitis in children has declined dramatically since the introduction of a vaccine, although rare cases in vaccinated children have been reportedS. aureus and coagulase-negative staphylococciWhat pathogen is an important cause of meningitis that occurs following invasive neurosurgical procedures, particularly shunting procedures for hydrocephalus?fever, headache, and nuchal rigidityWhat are the symptoms in the classic clinical triad of meningitis?>75%A decreased level of consciousness occurs in what percentage of bacterial meningitis patients and can vary from lethargy to coma?TrueTrue or False: Fever and either headache, stiff neck, or an altered level of consciousness will be present in nearly every patient with bacterial meningitis-nausea -vomiting -photophobia -seizureWhat are some of the other common complaints in bacterial meningitis?Increased ICPWhat is an expected complication of bacterial meningitis and the major cause of obtundation and coma in this disease?-reduced level of consciousness -papilledema -dilated poorly reactive pupils -sixth nerve palsies -decerebrate posturing -Cushing reflexWhat are the signs of increased ICP?Kernig's signElicited with the patient in the supine position, the thigh is flexed on the abdomen, with the knee flexed; attempts to passively extend the knee elicit pain when meningeal irritation is present.Brudinski's signElicited with the patient in the supine position and is positive when passive flexion of the neck results in spontaneous flexion of the hips and knees.Obtain blood cultures and start empirical antimicrobial and adjunctive dexamethasone therapyWhat interventions should be completed immediately when bacterial meningitis is suspected?(1) polymorphonuclear (PMN) leukocytosis (>100 cells/μL) (2) decreased glucose concentration (<40 mg/dL) and/or CSF/serum glucose ratio (<0.4) (3) increased protein concentration (>45 mg/dL) (4) increased opening pressure (>180 mmH2O)What are the classic CSF abnormalities in bacterial meningitis?>80%; >60%CSF bacterial cultures are positive in ___ of patients, and CSF Gram's stain demonstrates organisms in ___.Meningeal enhancementNot diagnostic of meningitis but occurs in any CNS disease associated with increased blood-brain barrier permeability-dexamethasone -third or fourth generation cephalosporin (e.g., ceftriaxone, cefotaxime, or cefepime) -vancomycin -acyclovir -plus doxycycline (during tick season)Empirical therapy of community-acquired suspected bacterial meningitis in children and adults should include what?HSV encephalitis is the leading disease in the differential diagnosisWhy is acyclovir is included in the empiric treatment of bacterial meningitis?ampicillinWhat antibiotic would you add to the empiric treatment of bacterial meningitis if listeria is suspected?metronidazoleWhat antibiotic would you add to the empiric treatment of bacterial meningitis if otitis, sinusitis, or mastoiditis is present?meropenemWhat antibiotic would you add to the empiric treatment of bacterial meningitis if you are treating a neurosurgical patient?penicillin GWhat is the antibiotic of choice for meningococcal meningitis?cefotaxime or ceftriaxoneCSF isolates of N. meningitidis should be tested for penicillin and ampicillin susceptibility, and if resistance is found what antibiotic should be substituted for penicillin?7 day; IVA _____ course of ___ antibiotic therapy is adequate for uncomplicated meningococcal meningitis-2 day regimen of rifampin (OR) -one dose of azithromycin 500 mg (OR) -one IM dose of ceftriaxone 250 mgAll close contacts of those with meningococcal meningitis should receive chemoprophylaxis with what?Pregnant womenRifampin is not recommended for who?cephalosporin (ceftriaxone, cefotaxime, or cefepime) and vancomycinAntimicrobial therapy of pneumococcal meningitis is initiated with what antibiotics?2-week; IVA ____ course of ____ antimicrobial therapy is recommended for pneumococcal meningitisLP performed 24-36 hours after the initiation of antimicrobial therapy to document sterilization of the CSFPatients with S. pneumoniae meningitis should have what repeated and why?24-36 hoursFailure to sterilize the CSF after ______ of antibiotic therapy should be considered presumptive evidence of antibiotic resistanceIntra-ventricular vancomycinPatients with penicillin- and cephalosporin-resistant strains of S. pneumoniae who do not respond to intravenous vancomycin alone may benefit from the addition of what therapy?Because adequate concentrations of vancomycin in the cerebral ventricles are not always achieved with intrathecal administrationWhy is the intra-ventricular route of administration preferred over the intrathecal route?ampicillin for at least 3 weeksMeningitis due to L. monocytogenes is treated with what?GentamicinWhat antibiotic is added in critically ill patients with meningitis due to L. monocytogenes?trimethoprim/sulfamethoxazoleWhat antibiotic may provide an alternative in penicillin-allergic patients with meningitis due to L. monocytogenes?NafcillinMeningitis due to susceptible strains of S. aureus or coagulase-negative staphylococci is treated with what?VancomycinWhat is the drug of choice for methicillin-resistant staphylococci and for patients allergic to penicillin?Either intra-ventricular or intrathecal vancomycin (20 mg once daily)In a patient with staphylococci meningitis, if the CSF is not sterilized after 48 h of intravenous vancomycin therapy then what treatment should be added?third-generation cephalosporins (cefotaxime, ceftriaxone, or ceftazidime) for 3 weeksGram-negative bacillary meningitis should be treated with what antibiotic?ceftazidime or meropenem for 3 weeksGram-negative bacillary meningitis due to P. aeruginosa which should be treated with what?decreasing CSF outflow resistance and stabilizing the blood-brain barrierHow does dexamethasone work in treating bacterial meningitis?20 min before, or not later than concurrent with, the first dose of antibioticsWhen should therapy with dexamethasone ideally be started?TrueTrue or False: Dexamethasone is unlikely to be of significant benefit if started >6 h after antimicrobial therapy has been initiated(1) decreased level of consciousness on admission (2) onset of seizures within 24 h of admission (3) signs of increased ICP (4) young age (infancy) and age >50 (5) the presence of co-morbid conditions (e.g. shock or mechanical ventilation) (6) delay in the initiation of treatmentThe risk of death from bacterial meningitis increases with what?-decreased intellectual function -memory impairment -seizures -hearing loss -dizziness -gait disturbancesCommon sequelae of bacterial meningitis include what?Decreased CSF glucose concentration and markedly increased CSF protein concentrationCSF findings that have been predictive of increased mortality and poorer outcomes in some series include what?