Acute Meningitis

Reşat ÖZARAS, MD, Prof.

Infection Dept.

rozaras@yahoo.com

CNS INFECTIONSOverview

Life-threatening problems with – High mortality – High morbidity

Presentation – acute, – subacute, – chronic

Clinical findings determined by anatomic site(s) of involvement, infecting pathogen, and host response

ACUTE CNS INFECTIONS

1. Bacterial meningitis

2. Meningoencephalitis

3. Brain abscess

4. Subdural empyema

5. Epidural abscess

6. Septic venous sinus

thrombophlebitis

Routes of Entry

– Hematogenous

– Neighboring focus

– Anatomic defect

• congenital

• traumatic

• surgical

– Intraneural pathways

Acute Meningitis

THE PATIENT WITH ACUTE CNS INFECTIONOverall Goals in Management

1. To promptly recognize the patient with an acute CNS infection syndrome

2. To rapidly initiate appropriate empiric therapy

3. To rapidly and specifically identify the etiologic agent, adjusting therapies as indicated

4. To optimize management of complicating features

APPROACH TO THE PATIENT WITH SUSPECTED MENINGITIS

Decision-Making Within the First 30 Minutes

Clinical Assessment

Mode of presentation Acute (< 24 hrs)

Subacute (< 7 days) Chronic (> 4 wks) Historical/physical exam clues

Clinical status of the patient

Integrity of host defenses

Clinical Features Fever Headache Nuchal rigidity Altered mental status Photophobia Non-specific symptoms/signs Focal neurological signs Seizures Specific clinical stigmata according to etiological agent Children / elderly

rushemergencymedicine.com

CSF STUDIES

Color/Clarity Cell counts/WBC diff Chemistries (protein, glucose) Stains/Smears (Gram) Cultures (routine) +/- Antigen screens

APPROACH TO THE PATIENT WITHSUSPECTED MENINGITIS

Decision-Making at 1-2 Hours

CSF Analysis

CSF smears/stainsCSF antigen screens

CSF “profile”

CSF SMEARS & STAINS

GmS + in 60-90% of pts with untreated bacterial meningitis

With prior ATB Rx, positivity of GmS decreases to 40-60%

REMEMBER: + GmS = Heavy organism burden & worse prognosis

CSF ANTIGEN SCREENS

Bacterial antigen screens detect

S. pneumoniae, N. meningitidis, Hib; + in 50-100% of pts (esp. useful in pts with prior ATB Rx)

Crypto antigen screen detects C. neoformans; + in 90-95% of pts with crypto meningitis

Should NOT be a ordered routinely

CEREBROSPINAL FLUID PROFILES

Neutrophilic/Low glucose (purulent)

Lymphocytic/Normal glucose

Lymphocytic/Low glucose

APPROACH TO THE PATIENT WITH SUSPECTED MENINGITIS

Decision-Making at 24-48 hours

CSF Culture Results

Culture positive Adjust therapy based upon specific organism and sensitivities

Culture negative Evaluate for “aseptic” meningitis syndrome

TO LP OR NOT TO LP

Single most impt diagnostic test Mandatory, esp if bacterial

meningitis suspected If LP contraindicated, obtain BCs (+

in 50-60%), then begin empirical Rx

THE PATIENT WITH SUSPECTEDCNS INFECTION

Contraindications to LP

Absolute: Skin infection over site

Papilledema, focal neuro signs, ↓MS

Relative: Increased ICP without papilledema

Suspicion of mass lesion

Spinal cord tumor

Spinal epidural abscess

Bleeding diathesis or ↓ plts

CNS INFECTIONSCT

Over-employed diagnostic modality Leads to unnecessary delays in Rx & added cost

Rarely indicated in pt with suspected acute meningitis

Mandatory in pt with possible focal infection Increased sensitivity with contrast

enhancement

THE THERAPY OF MENINGITISDesirable Antimicrobic Properties

1. Activity vs suspected pathogen(s)

[preferably cidal]

2. Adequate CSF diffusion

3. Acceptable risk of toxicity

THE THERAPY OF MENINGITISCNS Penetration

Good Diffusion

Penicillins

3rd& 4th Gen Cephs

Chloramphenicol

Rifampin

TSX

Poor Diffusion

Early Gen Cephs

Clindamycin

AMGs

Tetracyclines

Macrolides

Bacterial MeningitisImportant Changes in Epidemiology

Marked decline in the occurrence of Hib ↑’ing incidence of S. pneumo (50+% of

cases in US) Shift from peds disease to adult disease ↑’ing incidence of ATB-resistant

organisms, esp. S. pneumo– PCN resistance ~ 35% (15-20% high level)– Ceph resistance 15-20% (5-10% high level)

COMMON BACTERIAL PATHOGENS BASED ON PREDISPOSING FACTOR IN PATIENTS WITH MENINGITIS

Predisposing FactorAge 0-4 wk

4-12 wk

3 mo to 18 yr 18-50 yr >50 yr

Common Bacterial Pathogens

Streptococcus agalactiae, Escherichia coli, Listeria monocytogenes, Klebsiella pneumoniae, Enterococcus spp., Salmonella

spp.S. agalactiae, E. coli, L. monocytogenes, Haemophilus influenzae, Streptococcus pneumoniae, Neisseria meningitidisH. influenzae, N. meningitidis, S. pneumoniaeS. pneumoniae, N. meningitidisS. pneumoniae, N. meningitidis, L. monocytogenes, aerobic gram-negative bacilli

Etiology - in Adults

S. pneumoniae 30-50% N. meningitidis 10-35% H. influenzae 1-3% G -ve bacilli 1-10% Listeria species 5% Streptococci 5% Staphylococci 5-15%

EMPIRIC THERAPY OF MENINGITIS IN THE ADULT

Clinical Setting Likely Pathogens Therapy

Community-acquired S. pneumoniae CeftriaxoneN. meningitidis 2 gm q12h[Listeria] +[H. influenzae] Ampicillin 2 gm

q4h

Closed head trauma S. pneumoniae Pen G 3-4 mu q4hStreptococci +

Vancomycin 1-2 gm q12h

Role of Steroids The addition of anti-inflammatory agents has been attempted

as an adjuvant in the treatment of meningitis

Early administration of corticosteroids for pediatric meningitis has shown no survival advantage, but there is a reduction in the incidence of severe neurologic complications and deafness

Less bilateral deafness late neurological sequelae in controls compared to children treated with steroids

Community-acquired S. pneumoniae CeftriaxoneN. meningitidis 2 gm q12h[Listeria] +[H. influenzae] Ampicillin 2 gm q4h

+Dexamethasone

VIRAL MENINGITIS/ENCEPHALITIS

Enteroviruses

Polioviruses

Coxsackieviruses

Echoviruses

Togaviruses Eastern equine

Western equine

Venezuelan equine

St. Louis

Powasson

California

West Nile

Herpesviruses

Herpes simplex

Varicella-zoster

Epstein Barr

Cytomegalovirus

Myxo/paramyxoviruses Influenza/parainfluenzae

Mumps

Measles

Miscellaneous Adenoviruses

LCM

Rabies

HIV

NONVIRAL CAUSES OF ENCEPHALOMYELITIS

Rocky Mountain spotted fever Acanthamoeba

Typhus Toxoplasma

Mycoplasma Plasmodium falciparum

Brucellosis Trypanosomiasis

Subacute bacterial endocarditis Whipple’s disease

Syphilis (meningovascular) Behcet’s disease

Relapsing fever Vasculitis

Lyme disease

Leptospirosis

Tuberculosis

Cryptococcus

Histoplasma

Naegleria

Cryptococcosis

Toxoplasmosis