Neisseria final.pptx
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The genus Neisseria consists of Gram negative, aerobic, catalase & oxidase positive, non-motile diplococci (arranged in pairs). Pathogenic Non-Pathogenic (commensals). Pathogenic species: -N. meningitidis (pyogenic menigitis) -N. gonorrhoeae (gonorrhoea) Non-pathogenic species: -N. flavescens -N. sicca N. subflava
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Neisseria final.pptx
- 1. Neisseria N. gonorrhoeae & N. menigitidis
- 2. GRAM NEGATIVE COCCI Genus-Neisseria • (a) N. gonorrhoeae (Gonococcus) • (b) N. meningitidis (Meningococcus) Genus–Moraxella • M. catarrhalis-Gm-ve diplococci, infections of respiratory system, middle ear, eye, CNS and joints; disease usually of immunocompromised hosts Genus-Acinetobacter Non motile coccobacilli, encapsulated and oxidase negative; widely distributed in nature & part of normal flora hence isolation does not alone signify etiology. Can infect any organ, tissue.
- 3. Neisseria • The genus Neisseria consists of Gram negative, aerobic, catalase & oxidase positive, non-motile diplococci (arranged in pairs). • Pathogenic • Non-Pathogenic (commensals). Pathogenic species: -N. meningitidis (pyogenic menigitis) -N. gonorrhoeae (gonorrhoea) Non-pathogenic species: -N. flavescens -N. sicca N. subflava
- 4. Neisseria Meningitidis ( meningococcus) First isolated by Weichselbaum in 1887, from the spinal fluid of a patient. Morphology: • They are gram negative, spherical or oval cocci, • 0.6-0.8 μm in size, • arranged in pairs with the adjacent sides flattened. • Non-motile. • Generally intracellular when isolated from lesions. .
- 5. Culture media: • They are fastidious organism.Do not grow on ordinary media. • Growth occurs on media enriched with blood or serum. These substances promote growth by providing additional nutrients. Blood agar, Chocolate agar and Mueller-Hinton agar are commonly used media. • Selective media: Thayer Martin medium with antibiotics (Vancomycin, Colistin, Nystatin & Trimethoprim), Martin- Lewis (ML) medium & New-York City(NYC) medium
- 6. Thayer-Martin agar (or Thayer-Martin medium) • Mueller-Hinton agar with 5% chocolate sheep blood and antibiotics. It is used for culturing and primarily isolating pathogenic Neisseria bacteria, including Neisseria gonorrhoeae It usually contains the following combination of antibiotics called VCN inhibitor: • Vancomycin, which is able to kill most Gram-positive organisms, although some Gram-positive organisms such as Lactobacillus and Pediococcus are intrinsically resistant; • Colistin, which is added to kill most Gram-negative organisms except Neisseria, although some other Gram-negative organisms such as Legionella are also resistant; • Nystatin, which can kill most fungi. • Trimithoprim, which inhibits Gram-negative organisms, especially swarming proteus
- 7. Culture media (cont.) Thayer Martin medium & Martin-Lewis (ML) medium are Chocolate based media, while New-York City(NYC) medium is a clear peptone-cornstarch agar based medium. All the three media contain antibiotics to inhibit bacteria, yeasts & molds. These media can be used to grow *N. gonorrhoeae. They are strict aerobes & can’t grow anaerobically. The optimum temperature & pH for growth are 35°C-36°C & 7.4-7.6 respectively. A moist environment with 5-10% CO2 is must for the growth to occur. On solid media, the colonies are small (1mm in diameter), round, convex, grey, translucent with entire edges. The colonies are butyrous in consistency & easily emulsifiable. In liquid media, it produces granular turbidity.
- 8. Biochemical Reactions • N. meningitidis is catalase & oxidase positive. • The prompt oxidase reaction helps to identify neisseria (both meningococci & gonococci in mixed cultures). • Glucose & maltose are fermented with acid production but no gas (gonococci ferment glucose but not maltose). They do not ferment lactose or sucrose. Indole & H2S are not produced & nitrates are not reduced.
- 9. Oxidase Test When freshly prepared oxidase reagent (1% tetramethyl paraphenylene diamine hydrochloride) is poured on the culture plate, neisseria colonies become deep purple.(Oxidase-positive bacteria possess cytochrome oxidase or indophenol oxidase (an iron-containing hemoprotein). The test may also be performed by rubbing bacterial growth with a loop on a filter paper strip moistened with the oxidase reagent. A deep purple colour is a positive reaction.
- 10. Resistance • These are very delicate organisms, being highly susceptible to heat, dessication & to disinfectants. • They are susceptible to Penicillin, Ampicillin, Chloramphenicol, Macrolides & Ciprofloxacin. • Strains resistant to Penicillin have been reported in several countries.
- 11. Pathogenesis • Cerebrospinal meningitis & meningococcal septicemia are two main types of meningococcal disease. • Meningococci are strict human parasites inhabiting the nasopharynx. • Infection is usually asymptomatic. • In some, local inflammation leads to rhinitis & pharyngitis. • Dissemination occurs only in a small proportion. • The cocci spread from the nasopharynx to the meninges may be directly along the olfactory nerve, through the cribriform plate to the subarachnoid space, or more probably, through the bloodstream. • In certain cases the site of entry of the meningococcus may be conjunctiva.
- 13. Laboratory identification • Under light microscope (Centrifuged) CSF smear show gram negative diplococci in association with polymorphs. • Carriers can be detected by culturing swabs from nasopharyngeal region. Can be cultured easily from CSF or blood on plain chocolate agar (as they are normally sterile). Thayer Martin medium is required for samples obtained from a skin lesion or a nasophryngeal swab to eliminate contaminating organisms. • Meningococcus is oxidase positive and ferments both glucose & maltose. • CSF cytology & biochemistry gives clue.
- 14. TREATMENT & PREVENTION • Penicillin/Chloramphenicol/ Cephalosporins • Prophylaxis: Rifampicin or Ciprofloxacin • Vaccines: Monovalent or Polyvalent(A,C,W135 and Y)
- 17. Characteristics of Neisseria gonnohorea • Gram-negative diplococci with adjacent sides concave (pear or bean shaped). • Infects mucus-secreting epithelial cells • Frequently appear as intracellular gram- negative diplococci within polymorphonuclear neutrophils; some cell may contain as many as hundred cocci. • Neisseria gonorrhoeae fastidious showing optimal growth on enriched chocolate agar. Neisseria gonorrhoeae in Urethral Exudates
- 18. Characteristics of Neisseria gonnohorea • Gonococci posses pilli on their surface. • Pilli facilitates adhesion of the cocci to mucosal surface & promotes virulence by inhibiting phagocytosis. • Infects mucus-secreting epithelial cells. • They agglutinate human RBCs.
- 19. Cultural Characteristics • Gonococci are non motile. More difficult to grow. • Are aerobic and facultative anaerobic. • pH 7.2-7.6 at optimum temperature 35-36℃. • Grow well on chocolate agar, Muller Hinton agar. • Selective medium (Thayer Martin medium)
- 20. Biochemical Reactions • Oxidase Positive • Catalase Positive • Ferments Glucose with acid but not Maltose .
- 21. 22 Transmission •Efficiently transmitted by: –Male to female via semen –Female to male urethra –Rectal intercourse –Perinatal transmission (mother to infant) •Gonorrhoea is associated with increased transmission of and susceptibility to HIV infection
- 22. 23 Complications in Men • Primary site: Urethera • Leads to Urethritis • Swollen or tender testicles (epididymitis) • Disseminated gonococcal infection (DGI) Gonorrhea
- 23. IN MEN: Most infections among men are acute and symptomatic with purulent discharge & dysuria (painful urination) after 2- 5 day incubation period Male host seeks treatment early preventing serious sequelae, but not soon enough to prevent transmission to other sex partners The two bacterial agents primarily responsible for urethritis among men are N. gonorrhoeae and Chlamydia trachomatis
- 24. 25 Gonorrhea Symptoms in Women • Primary site: Vagina • Usually asymptomatic often untreated until PID complications develop • Inflammation of the endocervix • Purulent vaginal discharge • Painful urination • Abnormal vaginal bleeding • Pain and bleeding during sexual intercourse
- 25. 26 Complications in Women •Pelvic inflammatory disease (PID) • May also be asymptomatic, but difficult diagnosis accounts for many false negatives • Can cause scarring of fallopian tubes leading to infertility or ectopic pregnancy •Disseminated gonococcal infection (DGI) • Result of gonococcal bacteremia • Often skin lesions • Petechiae (small, purplish, hemorrhagic spots) • Pustules on extremities • Arthralgias (pain in joints) • Septic arthritis • Occasional complications: Hepatitis, Rarely endocarditis or meningitis The acidic pH of vaginal secretions in female, due to the fermentation of glycogen by lactobacillus (normal flora), renders vagina free of many pathogens.
- 26. 27 Gonorrhea in Infants • A mother can pass gonorrhea to her baby during childbirth • Ophthalmia neonatorum Gonorrhea
- 27. Laboratory Diagnosis • Specimen: • Discharge or Uretheral swab, Endocervical swab • Specimens should be processed immediately using prewarmed culture plate or transported in Stuart’s transport medium. Stuart’s transport media
- 28. Gram’s staining: Small, gram-negative diplococci in presence of polymorphonuclear leukocytes (PMN’s) seen microscopically in purulent urethral discharge Susceptible to drying and cooling, so immediate culture of specimen onto pre-warmed selective (e.g., modified Thayer-Martin, Martin-Lewis agars) and non-selective media (chocolate blood agar) with moist atmosphere containing 5% carbon dioxide Laboratory Diagnosis
- 29. Lab Examination • Ferment Glucose with acid only. • Do not ferment maltose • Oxidase positive • Serology: • ELISA
- 30. Penicillin no longer drug of choice due to: •Continuing rise in the MIC Uncomplicated infections: ceftriaxone, cefixime or fluoroquinolone Combined with doxycycline or azithromycin for dual infections with Chlamydia Treatment of newborns with opthalmia neonatorum with ceftriaxone Treatment
- 32. Measures to limit epidemic include Education/ Counselling aggressive detection follow-up screening of sexual partners inappropriate self medication leads to widespread of antimicrobial resistance Prevention/ Control of Gonorrhea
- 34. MENINGOCOCCAL MENINGITIS: A RARE BUT POTENTIALLY DEVASTATING.