meningitis

MENINGITISDr .PRAVEEN NAGULA

MENINGITISMENINGITIS

Introduction

Infection predominantly involves the subarachnoid space---MENINGITIS.

Brain tissue directly involved is called as ENCEPHALITIS. Focal bacterial,fungal,parasitic infection involving brain tissue

– CEREBRITIS –absence of capsule,ABSCESS presence of capsule.

Nuchal rigidity (STIFF NECK ) – pathognomonic sign of meningeal irritation-resistance to passive flexion.

Classical signs of meningeal irritation –KERNIG’S,BRUDZINSKI’S sign.

MENINGES

Meninges

What is ?

MENINGISM :the symptoms and signs of meningeal irritation assosciated with acute febrile illness or dehydration without actual infection of the meninges…also called meningismus…PSEUDOMENINGITIS.

KERNIG’S SIGN

Patient to be in supine position. Thigh flexed on abdomen. Knee flexed. Attempt to passively extend knee elicit pain when irritation

is present.

BRUDZINSKI’S sign

Supine position. Passive flexion of neck –spontaneous flexion of hips

and knees.

Specificity and sensitivity of these tests –UNCERTAIN.

Where they could be absent are?

Immunocompromised Very young or elderly. Severely depressed mental state.

False positive – cervical spine disease..

IMPORTANT POINTS..

It is an emergency. Empirical antibiotics to be started. Do CT scan/MRI in case of immunocompromised,recent head

trauma,focal neurological deficits ---LP – but AB not to be delayed.

No depressed level of consciousness –think of viral meningitis. Immunocompetent ,consciousness good –can be treated on

OP basis. Failure of a patient to improve < 48 hrs – reevaluate the

patient,repeat LP ,lab studies and neurological examination.

ACUTE BACTERIALMENINGITIS

ACUTE BACTERIAL

MENINGITIS

It is an acute purulent infection within the subarachnoid space.

CNS INFLAMM

ATION

SEIZURES

INTRACRANIAL

PRESSURESTROKE

CONSCIOUSNESS

Most common orgnaisms responsible for community acquired bacterial meningitis

S.pneumoniae 50% N.meningitidis 25% Group B streptococci - 15% Listeria monocytogenes 10% Hemophilus influenzae 10%

Based on age

AGE ORGANISM

NEONATES L.monocytogenes

2- 20 yrs N.meningitidis

18-50 yrs S.pneumoniae,N.meningitidis

>50 yrs Listeria monocytogenes,gram negative

Impaired cell mediated immunity

L.monocytogenes,gram negative

Post surgical ,post traumatic S.aureus,S.pneumoniae,gram negative

Pregnancy L.monocytogenes

Unvaccinated children H.influenzae

TRIAD OF MENINGITIS

Fever

Headache

Neck stifness

ETIOLOGY

PNEUMOCOCCAL – from pneumonia,otitis

media,alcoholism,diabetes,splenectomy,hypogammaglobulinemia,complement deficiency,head trauma.

20% mortality depsite antimicrobial Rx. N.meningitidis -25% of all cases.

Petechiae or purpuric skin rash. Fulminant –death within hours

ENTERIC gram negative – chronic debilitating diseases. S.agalacticae -- >50 yrs of age. L.monocytogenes –ingestion of food contaminated.

PATHOGENESIS

Nasopharyngeal colonization –asymptomatic carrier.

Invasive meningeal disease Depends on bacterial

virulence factor ,host immune defense mechanisms

Deficiency of complementHighly susceptible

Host immune defense

mechanisms

Bacterial virulence

pathogenesisBacteri

a

Colonize Nasophra

yngeal epithelial

cells

Intravascular

spacePolysaccharide

capsuleAvoids

phagocytosis

Intraventricular

Choroid plexusGain

accessTo CSF

Multiply,absence ofImmune defences

Inflammatory reactio

nLysis of bacteria,cytokines

TNF,IL1

COMPLICATIONS

Much of the pathophysiology is due to direct consequence of chemokines,cytokines.

TNFIL1

Vascular permeabilitiy

Vasogenic

edema

Exudate in

CSFObstructivehydrocepha

lus

IncreasedLeukocyte adherence

Leakage into CSF

Degranulation of

neutrophils

chemokines

Excitatory Aminoacids

Death Of brain cells

Clinical features

Decreased level of consciousness >75% Nausea,vomiting,photphobia common Classical triad –less sensitivity Only two may be present nearly in all cases. Seizure –initial presentation in 20-40% cases Focal –focal arterial ischemia,cortical venous

thrombosis,focal edema GTCS– hyponatremia,anoxia,high dose penicillin. RAISED ICP- >90 % have CSF pressure – 180mmH20 20% -- 400mm H20 Rash of meningococcemia – diffuse,petechial;

DIAGNOSIS

CSF analysis Blood cultures CT scan/MRI --- LP Latex agglutination – S.pneumoniae,N.meningitidis Lumulus lysate –gram negative

In case of immunocompetent,no h/o head trauma,no evidence of papilledema –LP without CT scan

AB therapy to be started hrs before LP –no change in analysis,or visualization of organisms

CSF analysis

CSF glucose may be zero – CSF/serum glucose corrects for hyperglycemia CSF/s.glucose < 0.6 CSF/s.glucose < 0.4 –

bacterial,fungal,tuberculosis,carcinomatosis 30 min to several hours to reach equilbrium with blood

glucose levels –so can start 50 ml of 50 % D. PCR –useful in pretreated pts,gram stain negative MRI >CT for cerebral edema Diffuse meningeal enhancement --gadolinium –

increased permeability of BBB.

Differential diagnosis

HSV mimics bacterial meningitis –differentiated by CSF,EEG,neuroimaging.

RICKETTESIAL- rash—petechiae—necrosis—gangrene,distal

Non infectious – SAH,Chemical meningitis Uveomeningeal syndrome – VogtKoyangiHarada syndrome Subacute –M.tuberculosis,c.noeformans,h.capsulatum

Treatment

BEGIN AB < 60 min Empirical treatment –dexamethasone,cefotaxime or

ceftriaxone,vancomycin,azithromycin,acyclovir,doxycycline. Post op cases –

ceftazidime,cefepime,meropenem,vancomycin Then change according to culture reports

Meningococcal

PENICILLIN G is DOC In case of resistance – Ceftriaxone,cefotaxime Uncomplicated course--7 day course. All close contacts should receive chemoprophylaxis – 2 day

regimen of rifampicin 600 mg every 12 hrs * 2days/ciprofloxacin 750 mg od/azithromyxin 500 mg OD/ceftriaxone 250 mg OD

Who are close contacts --- nasopharyngeal secretions,kissing,toys,beverages use.

pneumococcal

Cephalosporin plus vancomycin If resistance – vancomycin Rifampin can be added synergistic action 2 week course Repeat LP after 24-36 hrs –sterilization of CSF –if not

introventricular vancomycin

Listeria and others

Ampicillin for 3 weeks Gentamicin 2mg/kg/d loading – 7.5 mg/kg/d every 8hrs TMP SMX –every 6hrs

STAPHYLOCOCCAL –vancomycin

Gram negative – 3 weeks of third generation cephalosporin.

Adjunctive therapy

Dexamethasone – decreases synthesis of IL1,TNF,stabilises BBB

20 min before AB Rx Inhibits TNF production by macrophages only before

activated by endotoxin. Decreases penetration of vancomycin into CSF. 10 mg IV 30 min before AB every 6hrs -4 days.

Raised ICP

Elevate head end of bed 30-45 Intubation Hyperventilation PaCo2 – 25-30 mm Hg mannitol

prognosis

20% mortality –pneumococcal 15% - listerias 3-7% h.infleunzae,gram negative.

Who are at risk of poor prognosis

Decreased level of consciousness at admission Seziures < 24 hrs of onset Raised ICP Young age,>50 yrs Mechanical ventilation Delay in treatment <40 mg /dl -glucose >300 mg/dl -protein

sequelae

Decreased intellectual function Memory impairement Seizures Hearing loss Gait disturbances

SUMMARY

Acute bacterial meningitis is an emergency Triad is seen less commonly Pathognomonic feature is neck rigidity Altered level of consciousness and seziures can be the

presenting features. S pneumoniae is the most common organism overall Other organisms based on the age ,and clinical background CSF analysis after CT scan is the rule… PMNs,hypoglycoracchchia,raised proteins and pressure is

the hallmark PCR to be done only in negative cases MRI for cerebral edema

Antibiotics for a week in case of uncomplicated meninogcocci,2 weeks in s pneumoniae,3 weeks listeria.

All close contacts to be given chemoprophylaxis in case of meningococci with rifampicin 600 mg bid for 2 days.

Triad of meningitis is fever,headache,neckstiffness Postoperative cases think of s aurues,gram negative. Ampicillin to be given in case of suspicion of listeria for 3

weeks S. pneumoniae has high mortality of 20%

Antibiotic treatment not to be delayed for the results of investigations

Third generation cephalosporins,vancomycin,ampicillin durgs empirically will cover all organisms.

Dexamethasone for stabilising BBB,to be given beofre AB. HSV encephalitis is closest DD 1 week therapy in case of meningococci,2 weeks

pneumoniae,3 weeks –listeria Raised ICP –hyperventilate,raise head end,mannitol Sequelae decrease on early management 20% mortality in case of s.pneumoniae