Pyogenic cocci Neisseriae

Neisseria meningitides (Meningococci) At least 13 serologic groups on the basis of the antigenicity of their capsular polysaccharide (A, B, C, D, X, Y, Z, W135, 29E, H, I, K, and L). The route of infection is nasopharynx, MC present as normal flora of nasopharynx, these MC stimulate the carrier antibodies( natural immunity ) these carrier are asymptomatic.
Two organisms cause more than 80% of cases bacterial meningitis in persons over 2 months of age : Streptococcus pneumonia and Neisseria meningitides of these organism. MC in group A cause epidemics of meningitis.
virulence factors (antigenic structures):- Meningococci have three virulence factors :- a. polysaccharide capsule which act antiphagocytic factor. D. Endotoxin (LPS) which cause fever, shock. C. IgA1 protease cleaves secretory IgA.
Pathogenesis and clinical finding :- Disease meningitis and meningococcemia, MC spread via respiratory secretions, MC via nasopharynx-blood stream bacteremia (meningococcemia) intravascular coagulation and spread-meningitis most common complication of meningococcemia-fulminant meningococcemia (septic shock). Meningitis most common disease in children less than 1 year.
Lab. Diagnosis :- 1. Specimens from blood, CSf and nasopharyngeal swap. 2. Direct-Gram stain smear of centrifuged CSF shows MC as typical Neisseria within polymorphonuclear leukocyte or extracellularly.
3. Culture, CSF specimen are plated on Choclate agar and incubated at 37oC with 5% CO2. Also culturing in Thayer martin agar and modified TM.
4. Biochemical test :- --Oxidase test-positive. --Sugar fermentation test, ferment maltose and glucose. 5. Serology, antibodies to meningococcal polysaccharides can be measure by latex agglutination test or by measuring the bactericidal activity. These antibodies give
Treatment :- Penicillin G is the drug of choice.
Prevention and control :-
Vaccine contains capsular polysaccharide of strains A, C, Y and W-135, rifampin or ciprofloxacin given to clos contact to decrease oropharyngeal carriage. Moraxella catarrhalis :-normal flora of the upper respiratory tract, it causes bronchitis, pneumonia, otitis media and conjunctivitis, this spp. Produce beta-lactamase so its resistant to peniciliin. It produces butyrate esterase.