Gram negative cocci

Gram negative cocci, Neisseriae, NEISSERIAE MENINGITIDIS, DISEASES, IMPORTANT PROPERTIES , PATHOGENESIS & EPIDEMOLOGY , CLINICAL FINDINGS, TREATMENT , PREVENTION, NEISSERIAE GONORRHOEAE

1. GRAM NEGATIVE COCCI Presented by SYEDA MARYAM

2. Neisseriae Gram negative cocci Shape of paired kidney beans Inhibited by toxic trace metals fatty acid found in certain culture media Cultured on chocolate agar contain blood heated to 80C inactivates the inhibitors Is oxidase positive contain enzyme CYTOCHROME C important laboratory diagnostic test PHENYLENEDIAMINE turns purple/black as a result of oxidation of reagent by enzyme

3. NEISSERIAE MENINGITIDIS Also known as MENINGIOCOCCI

4. DISEASES MENINGITIS MENINGOCOCCEMIA

5. IMPORTANT PROPERTIES Prominent polysaccharide capsule antiphagocytic enhances virulence immunogen in vaccine induces protective antibody Divided into 13 serologic groups based on antigenicity of their capsular polysaccharide most common cause of meningitis /meningococcemia group A, B, C, Y, W-135 group A leading cause of epidemic meningitis group B not immunogenic in human not part of vaccine that contain capsular polysaccharide

6. PATHOGENESIS & EPIDEMOLOGY Human is only natural host of N. meningitides Transmitted by air borne droplet Colonizers of nasopharynx become part of transient flora of upper respiratory tract Carriers are usually asymptomatic Enter blood stream from nasopharynx spread to specific site MENINGES & JOINTS disseminated through out the body MENINGIOCOCCEMIA 5% people become chronic carrier source of infections for others Meningitis in infants older than 2 months strep. Pneumonia N. meningitides group A epidemic meningitis group B meningitis in developed countries

7. 4 impotant virulence factors POLYSACCHRIDE CAPSULE enable organism to resists phagocytosis is immunogen used in several vaccines ENDOTOXINS causes fever, shock and pathophysiologic changes IMMUNOGLOBULIN IgA PROTEASE help bacteria to attach to membrane of upper respiratory tract cleaves secretory IgA FACTOR H BINDING PROTEIN (FHBP) bind factor H inhibitors of complement C3b it’s presence on the surface of meningococci reduces opsonization

8. Immunity is group specific immunity against on group yet susceptible to infection by another group Resistance to disease correlates to the presence of antibody to the capsular polysaccharide Most carriers develop antibody titter against it within 2 weeks of colonization Complement deficiency i.e. LATE ACTING COMPLEMENT (C6-C9) Increases the rate of meningococcal bacteremia

9. CLINICAL FINDINGS 2 most important manifestations are MENINGITIS MENINGOCOCCEMIA WATERHOUSE- FRIDERICHSEN SYNGROME Is a life threatening form of meningococcemia is characterized by high fever shock widespread purpura DIC thrombocytopenia adrenal insufficiency Bacteremia results in seeding of many organs i.e. meninges symptoms are increased level of PMN in spinal fluid fever, headache, stiff neck

10. LABORATORY DIAGNOSIS Smear and culture of blood and spinal fluid samples Presumptive diagnosis can be made if Gram negative cocci is seen in the CSF of spinal fluid Grow best on chocolate agar incubated at 37C and 5% CO2 atmosphere Differentiation between N. meningitides and N. gonorrhea N. meningitides ferments MALTOSE N. gonorrhea don’t ferment MALTOSE while both ferments GLUCOSE Also identified by immunofluorescence Procedure of rapid diagnosis LATEX AGGULTINATION TEST detects capsular polysaccharide in spinal fluid

11. TREATMENT Drug of choice for meningococci Ceftriaxone / penicillin G Strains resistant to penicillin G rarely emerges Strains resistant to SULFONAMIDE common

12. PREVENTION CHEMOPROPHYLAXIS Immunization For prophylaxis RIFAMPIN + CIPROFLOXACIN

13. NEISSERIAE GONORRHOEAE Also known as GONOCOCCUS

14. DISEASES Gonorrhea Neonatal conjunctivitis ( ophthalmic neonatorum ) Pelvic inflammatory disease PID

15. PATHOGENESIS & EPIDEMOLOGY Cause disease only in human Usually transmitted sexually Newborn is infected during birth Symptomatic in men and asymptomatic in women Pili most imp. Virulence factor mediate attachment to mucosal cell surface antiphagocytic Have no capsule Main host defense against gonococci are IgA, IgG, complement & neutrophil

16. CLINICAL FINDINGS Cause localized infection in genital tract disseminated with seeding of various organs via blood stream GONORRHEA in men causes urethritis dysuria purulent discharge epididymitis may occur in women infection in endocervix purulent vaginal discharge intermenstrual bleeding (cervicitis) ascending infection to uterine tube SALPINGITIS , PID result in sterility or ectopic pregnancy

17. DGIs arthritis tenosynovitis pustules in skin common cause of septic arthritis in sexually active adults Other infected sites includes anorectal area throat pharyngitis eyes purulent conjunctivitis

18. LABORATORY DIAGNOSIS Diagnosis of urogenital infections depend upon growth staining culture of discharge nucleic acid amplification test

19. TREATMENT CEFTRIAXONE in uncomplicated gonococcal infection GENTAMYCIN + AZITHROMYCIN if patient is allergic to penicillin G or cephalosporin

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