meningitis
DESCRIPTION
date:19/09/2011TRANSCRIPT
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