Gram Negative Aerobic Nonsporulating Nonmotitile Oxidase-negative Paired cocci

Two important pathogens, Neisseria meningitidis Neisseria gonorrhoeae and Neisseria lactamica(rare speceis)

Meningococcus;Diplococcus intracellularis meningitidis  It causes meningococcal meningitis(cerebrospinal fever)  Morphology ;

 Do not grow on ordinary media  Media enriched with blood,serum or ascitic fluid which promote growth by neutralising inhibiting substances  No growth occurs anaerobically  Optimum temp;35-36degrees  Optimum ph;  Growth is facilitated by 5-10% CO2 &high humidity

On solid media colonies are Small, Translucent, Round, Convex, Bluish grey with glistening surface and entire edges Weak hemolysis on blood agar

Commonly used media, a. Blood agar b. Chocolate agar c. Muller-Hinton starch casein hydrolysate agar. Selective medium;Modified Theyer-Martin(with vancomycin,colistin and nystatin)

Catalase-positive Oxidase-positive In kovac’s method-deep purple colour appears immediately. Indole &Hydrogen sulphide-Not Produced, Nitrates-not reduced

Based on capsular polysaccharide antigens,classified into 13 serogroups…… A,B&C-Most important. groupA-EPIDEMICS groupB-LOCALISED OUTBREAKS groupC-BOTH Groups 29-E,W-135 &Y:causes MENINGITIS

Very delicate organisms Highly susceptible Sensitive to penicillin &other antibiotics But resistant strains have emerged

Two main types of meningococcal diseases, 1.cerebrospinal meningitis& 2.meningococcal septicemia. Strict human parasites inhabiting the nasopharynx Asymptomatic infection Local inflammation-rhinitis&pharyngitis

 cocci from nasopharynx cribriform plate to subarachanoid space meninges suppurative lesions surface of spinal cord, base&cortex of the brain spinal fluid

Cocci are found both free & with in leucocytes in the spinal fluid. Fatality high in untreated cases(80%) Survivors may have blindness&deafness Chronic or reccurent meningitis

MENINGOCOCCEMIA Acute fever with chills Malaise & Prostration. Metastatic involvement of joints, ears, eyes, lungs & adrenals may occur 10%-pneumonia.

Fatal condition, Shock Disseminated intravascular coagulation& Multisystem failure Pathogenic agent-ENDOTOXIN released by autolysis Vascular endothelium is sensitive to endotoxin

Specimens collected, 1.spinal fluid 2.blood 3.swabs from nasopharynx. 1.Examination of CSF:-collected csf is devided into 3 parts. a)1 st portion-centrifuged & gram stained smears are prepared from deposits, supernatant-meningococcal antigens

B)2 nd portion-inoculated on blood or chocolate agar imp note-morphologically similar organisms. c)3 rd portion-over night incubation, subcultured on chocolate agar. 2.BLOOD CULTURE 3.NASOPHARYNGEAL SWAB 4.PETECHIAL LESIONS 5.AUTOPSY 6.RETROSPECTIVE EVIDENCE 7.MOLECULAR DIAGNOSIS.

Sulphonamides Iv penicillinG Chloramphenicol Cephalosporins Eradicative therapy-Rifampicin or ciprofloxacin

Chemoprophylaxis-Rifampicin or ciprofloxacin. Mono or Polyvalent vaccines-capsular polysaccharides of groups A,C,W-135 & Y are available. Single dose in older children & adults. Immunity is group spesific.