Bacterial meningitis

meningitis An inflammation of the leptomeninges . bacterial meningitis is a common complication of septicemia in children and must be treated as an emergency. Caused by : bacteria, viruses , or rarely fungi . viral infection of the CNS are much more common than bacterial infection

meningitis Bacterial meningitis is one of the most potentially serious infection ,in infants and older children . Associated with a high rate of acute complications and risk of long-term morbidity. The etiology of meningitis in the neonate and the treatment are generally distinct from in older children

meningitis A limited number of bacteria are associated with meningitis in normal hosts . the principle of supportive management and the initial choice of antibiotics can be generalized.

Etiology of meningitis 2 month – 12yr: S .pneumonia, N . Meningitidis ,H .influenza type b. H .influenza type b is the most common cause of meningitis in children < 4-yr

Etiology and epidemiology of meningitis 2 month : maternal flora and environment . Group B and D. streptococci gram – negative enteric bacilli . and listeria monocytogenes. may be due H.Influenza type b and nonecapsulate and other pathogens

Etiology and epidemiology of meningitis Lack of immunity ( IgM or igG anti capsular antibody ) to specific pathogens with young age. recent colonization with pathogenic bacteria . Close contact with invasive disease ( respiratory tract secration) Crowding , poverty , black race , male . Defect in complement (C5- C8 ) associated with recurrent meningococcal infection .

Etiology and epidemiology of meningitis ventricular-peritoneal shunts: Coagulase negative staphylococci and corynebacteria . CSF leaks due to fracture cribriform palate or paranasal sinus ( pneumococcal ). head trauma or neurosurgical procedures ( staphylococci )

Etiology and epidemiology of meningitis Splenic disfunction (sickle cell anemia or asplenia ) increased risk of pneumococcal , H.influenza type b ,rarely meningococcal sepsis and meningitis . Immuno-suppressed patients with T-cell defects (AIDS, and malygnancy) : Cryptococcal and L.monocytogens. Open neural tube defect : Meningomyelocele and lombosacral dermal sinus associated with staphylococci -Aureus and gram – negative .

pathogenesis Bacterial meningitis is usually hematogenous. (endocarditis , pneumonia , or thrombophlebitis , burns , indwelling catheters ) Bacteremia precedes the condition or occur at the same time. microorganisms leads to nasopharyngeal colonization , replication , invasion , and bacteremia .

pathogenesis Bacteria entry to the CSF through the choroid plexus.and meningeal seeding , binding to specific receptors and production of local cytokines initiates inflammation. Neutrophilic infiltration , increase vascular premeablity , alterations of blood- brain barrier , and cerebral edema .

pathogenesis Meningitis rarely may be follow bacterial invasive from a contiguous focus of infection ; Paranasal synusitis , otitis media ,mastoiditis , orbital cellulitis, cranial osteomyelitis , penetrating cranial trauma ,meningomyeloceles , More often brain abscesses or epidural or subdural empyema follows contiguous infection .

Clinical manifestation Onset has two patterns; The more dramatic and less common is sudden onset(< 1 day ) rapidly progressive of shock ,purpura , DIC ,and reduce level of consciousness frequntly resulting in death in 24 hr ( S.pneumoniae , or N. meningitidis ) More often is preceded by several days of upper respiratory tract symptoms or GI symptoms . Subacute 2-3day .(H. influenzae)

Clinical manifestation In the young infants: fever usually is present and irritablity ,poor feeding , restlessness,may be noted. signs of meningeal inflammation may be minimal. Older child : confusion , back pain , usually Kernig and Brudzinski signs in some children particularly age < 12-18 mo are not present

Clinical manifestation Increased ICP headache , diolopia , emesis , bulging fontanel 3 or 6 nerve paralysis, hypertension with bradicardia ,apnea or hyperventilation ,stupor coma ( brain herniation ) inflammation of the meninges is associated with (headache ,nausea , vomiting , irritability , nuchal regidity , photophobia ) Arthritis ,arthralgia ,myalgia , anemia , petechia ,purpura

Clinical manifestation Papilledema is uncommon . intracranial abcess , subdural empyema or occlusion of a dural venous sinus Focal neurologic signs are due to vascular occlusion (10-20% ) Seizures occur in 20-30% Seizures that occure on presentation or within the first 4 days of onset are no prognostic significance

Clinical manifestation Seizures cerebritis, infarction , electrolyte Alteration of mental status increased ICP,cerebritis ,hypotension

Clinical manifestation Kernig sign: Flexion of the hip 90 degrees with subsequent pain with extension of the leg . Brudzinski sign : Involuntary flexion of the knees and hips after passive flexion of the neck while supine.

diagnosis Blood culture ( reveal responsible bacteria 50-90% ) LP analysis CSF for WBC count with diff ,protein, glucose ,Gram stain helpful in 90% , culture) CSF leukocyte count elevated >1000 and neutrophil (75-95%) In tramatic LP Gram stain ,culture , glucose level may not be influenced.

diagnosis when signs of increased ICP are present .  LP should be performed in every child when bacterial meningitis is suspected. Except : when signs of increased ICP are present . Infection at the LP site. Suspicion of a mass lesion. Extreme patient instability. Thrombocytopenia is a relative contraindication.

diagnosis Patient in the flexed lateral decubitus position . Intervertebral space L3-L4 or L4-L5.  Turbid CSF when CSF leukocyte count >200-400. Pleocytosis may be absent and is a poor prognostic sign. Pleocytosis with a lymphocytosis may be present during early stage of acute meningitis

Differential diagnosis Acute viral meningoencephalytis( PMN may be prodominant) Partial treatment of a acute bacterial meningitis . (glucose , protein , neutrophile are not aletread) TB ,fungal , spirochete ,,brain abcess , encephalitis bacterial endocarditis with embolism ,subdural empyema , subarachnoid hemmorhage , Careful examination CSF ,and additional laboratory tests are important .

CSF findings pressure leukocyte proteinmg/dl glucosemg/dl Normal 50-180mm <4 ,60-70%lymph 20-45 >50 or75% blood Bacterial 1 00-60,000 100-500 <40 Partial treat N 1-10,000 100 N Viral N 1000, lymph 20-100 generally N Abscess N 0-100 PMN 20-200 N

treatment Decreasing CSF damage caused by the inflammation response with dexamethasone 0.6mg/kg/24hr for 2 days Sterilization of CSF . Supportive therapy : Maintenance of adequate CNS systemic perfusion. Treatment shock , DIC, SAIDH , seizures , ICP increased ,apnea ,arrhythmia ,coma .

complication Subdural effusion : in 10-30% that asymtomatic in 85-90%. Seizure ,increased ICP ,nerves palsies ,stroke ,cerebral or cerebellar herniation ,thrombosis venous sinuses, Subdural effusion : in 10-30% that asymtomatic in 85-90%. In Symptomatic patient with increased ICP depressed consciousness aspiration must be done. Fever alone is not indication of aspiration.

treatment Empirical choice must cover S.pneumoniae . Many of which are Relatively resistance to penicillin (mic0.1-1) is more common than high – level resistance . Cefotaxime (200-300 mg/kg/24) or ceftrixone (100mg/kg/24) plus vancomycin (60 mg/kg/24). Cefotaxime and ceftrixone also cover N.meningitidis or H .influenza type b. if L-monocytogenes is suspected ( infant<2 mo ) Ampicillin 200/kg/24hr plus ceftriaxone .

Duration of treatment S. Pneumoniae ( 10 -14 days) N.Meningitidis ( 7days) H.influenza (10 days) Gram negative meningitis should be treated for 3 WK or 2 WK after CSF sterilization . Patients with evidence of acute bacterial meningitis but no identifiable pathogen cetrixone for7-10 days.

repeat CSF examination Repeat LP indicated ; in neonate Gram negative meningitis In β – lactam resistance S, pneumoniae . CSF should be sterile within 24- 48 hr

Prevention in meningococcal meningitidis Chemoprophylaxis: for all close contacts of patients with meningococcal meningitis. with the rifampin 10mg/kg every 12 hr for 2 days (600mg) Close contacts : household,daycare ,direct exposure with oral secration ,

Prevention ( H, influenza) Rifampin should be given to all close family. 20 mg/kg /24hr once each day for 4 days.

prognosis Mortality rate H,influenza 8% , meningococcal 15%, for pneumococcal 25%. 35% survivors have some sequelae; Deafness: is the most common neurologic sequelae. 30% with pneumococcal meningitis and 10%meningococ ,5-20% H.influ. seizures ,learning disability ,blindness ,paresis , ataxia , hydrocephallus ,mental retardation

Poor prognosis Young age .(< 6mo) long duration of illness before antibiotic therapy. late –onset seizure (>4days). shock ,coma, focal neurologic sign low or absent CSF WBC in the presence of visible bacteria on gram stain of CSF . immuno compromised status.

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