Bacterial meningitis

meningitisAn 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

meningitisA 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;

1. 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 )

2. More often is preceded by several days of upper respiratory tract symptoms or GI symptoms . Subacute 2-3day .(H. influenzae)

Clinical manifestation

1. In the young infants:

fever usually is present and irritablity ,poor feeding , restlessness,may be noted.

signs of meningeal inflammation may be minimal.

2. 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

LP should be performed in every child when bacterial meningitis is suspected. Except :

1. when signs of increased ICP are present .

2. Infection at the LP site.

3. Suspicion of a mass lesion.

4. Extreme patient instability.

5. 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

1. Decreasing CSF damage caused by the inflammation response with dexamethasone 0.6mg/kg/24hr for 2 days

2. Sterilization of CSF .

3. Supportive therapy :

Maintenance of adequate CNS systemic perfusion.

Treatment shock , DIC, SAIDH , seizures , ICP increased ,apnea ,arrhythmia ,coma .

complication 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 ;

1. in neonate

2. Gram negative meningitis

3. 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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