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Key Words • • • • •

Neisseria Thayer Martin Medium Oxidase test N. gonorrhoeae Gonorrhea, Ophthalmia neonatorum, Septic arthritis • N. meningitidis • Meningitis, Cerebral spinal Fever, WaterhouseFriedrichsen Syndrome 2


Neisseria gonorrhoeae 3

Neisseria: Natural Habitats • Neisseria gonorrhoeae an obligate pathogen with invasive infection of anogenital, oropharyngeal, and conjunctival mucous membranes • Neisseria meningitidis normally colonizes oropharyneal and nasopharyngeal mucous membranes of humans (carrier rate of 8-20%)

Neisseria • Gram negative • Diplococci (pairs of cocci) • Oxidase positive

• Incubation 35-36 C • 5-10% CO2 essential • Very delicate and autolytic

• Culture – Chocolate agar » heated blood (brown) – Thayer Martin. • selective 5

Modified Thayer-Martin Agar • Colistin: Inhibits gram-negative flora (N. gonorrhoeae and N. meningitidis resistant to colistin, most saprophyic species of Neisseria susceptible) • Vancomycin: Inhibits gram-positive flora • Nystatin: Inhibits yeast flora • Trimethoprim: Inhibits swarming Proteus

Selected Biochemical Reactions for Identification of Neisseria and Moraxella catarrhalis1 N. gon N. men N. lac2 M. cat

Glu + + + –

Mal – + + –

Lac – – + –

Suc – – – –

DNa – – – +

Glu=glucose, Mal=maltose, Lac=lactose, Suc=sucrose, DNa=DNase, N. gon=N. gonorrhoeae, N. men=N. meningitidis, N. lac=N. lactamica, M. cat=Moraxella catarrhalis 2 Colistin-resistant saprophytic species of Neisseria 1

Neisseria gonorrhoeae: Modes of Infection • Neisseria gonorrhoeae spread by sexual contact, including genital, anogenital, and orogenital. Spread from infected mother to neonate as ocular infection during birth. Non-sexual transmission not documented.

N. gonorrhoeae the “Gonococcus" • Found only in human

• Gonorrhea - Second most common venereal disease (after chlamydia trachomatis) • N. gonorrhoeae of sexually-transmitted lower genital tract disease (acute urethritis in men, endocervicitis in women) • N. gonorrhoeae untreated can progress to epididymitis, prostatitis, urethral stricture, salpingitis, tubo-ovarian abscess, and pelvic inflammatory disease 9

Neisseria: Types of Infectious Disease • N. gonorrhoeae causes oral and anorectal infections as a result of oral or anal intercourse • N. gonorrhoeae disseminates with bacteremia and/or septic arthritis if untreated • Disseminated infection (bacteremia, pyogenic arthritis) by N. meningitidis and N. gonorrhoeae associated with deficiency in the terminal components of complement (C5-C8)

Smear • Polymorphonuclear cell • Gram negative cocci – many in cells


Antibiotic therapy • β lactamase-resistant cephalosporin – e.g. ceftriaxone • Resistant strains – common – produce β lactamases – destroy penicillin 12

Pathogensis • Adhesion to genital epithelium – outer membrane – pili * Antigenicity highly variable among strains • No vaccine

• IgA protease – also N. meningitidis 13

N. gonorrhoeae • Tissue injury – lipopolysaccharide – peptidoglycan


N. meningitidis (the “Meningococcus")


N. meningitidis • Resides in man only • Usually sporadic cases – mostly young children • Outbreaks – adults – crowded conditions *e.g. army barracks, dorms 16

Neisseria meningitidis: Modes of Infection • Neisseria meningitidis transmitted by inhalation of infectious air-born respiratory droplets or direct contact with infectious respiratory secretions.

Neisseria meningitidis upper respiratory tract infection – adhesion pili


brain 18

Meningococcal meninigitis • Second most common meningitis – pneumococcus, most common • Fatal if untreated • Responds well to antibiotic therapy – penicillin


Neisseria: Types of Infectious Disease • N. meningitidis causes a rapidly progressive meningitis in school-aged children, adolescents, and young adults with a mortality of 7-13% • N. meningitidis bacteremia (mortality of 19-70%) a cause of WaterhouseFriderichsen syndrome with petechiae, purpura, adrenal hemorrhage, disseminated intravascular coagulation, and

Neisseria Meningitidis

Characteristics of N. meningtidis • Neisseria meningitidis encapsulated (capsule the major virulence factor) • Thirteen capsular polysaccharide serogroups • Invasive infection caused by organisms with one of five capsular serogroups (A, B, C, Y, and W135) with 90% of meningococcal disease due to serogroups A, B, and C

Capsule • Capsule – inhibit phagocytosis • Anti-capsular antibodies – stop infection •Antigenic variation – sero-groups • Vaccine –multiple sero-groups 24

Laboratory Diagnosis • Spinal fluid –

Gram negative diplococci

• Within polymorphonuclear cells • Detection of –

• • • •

CSF – Pressure Glucose Proteins Chlorides Normal

Meningococcal antigens

Culture –

Blood /Chocolate Agar


Neisseria Meningitidis • Treatment -Penicillin - rifampicin or Minocycline- prophylaxis - Vaccine- polyvalent vaccine A,C,Y,W135

Moraxella catarrhalis: Types of Infectious Disease • Acute purulent exacerbation of chronic bronchitis • Causes 10-15% of episodes of otitis media and sinusitis • Rarely associated with systemic infection (endocarditis, meningitits)