Neisseria Gonorrhea_microb (Lect 22-11)

7/30/2019 Neisseria Gonorrhea_microb (Lect 22-11)

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ProtozoaFungalViralBacterial

Trichomonas vaginalis

↓

Trichomonasgenital

infections

Candida albicans

↓

Vaginalthrush,balanitis

• Herpes simplex (type 2 mainly) → Genital herpes

• Papilloma virus → Genital warts

• Hepatitis B and

may be C→ Hepatitis

• HIV→ AIDS

• CMV → CMVinfection

• Pox Virus → Molluscumcontagiosum

• Neisseria gonorrhoeae → Gonorrhea

• Haemophilus ducreyi →

Chancroid (soft chancre)• Treponema pallidum → Syphilis

• Chlamydiae :

-Chlamydia trachomatis (D

- K) → Non-specificurethritis

- Chlamydia trachomatis (L1,2,3) → Lymphogranuloma venereum(LGV)

• Mycoplasma: - Ureaplasma urealyticum → Non-specific urethritis



NEISSERIA GONORRHOEAE



• Morphology:

Identical to N. meningitidis .



•Culture

Delicate organism, exacting nutritional andenvironmental

requirements:

- Aerobe , ↑CO2.

- Optimum temperature: 37 C.

- Enriched media: chocolate agar.- Selective media: Thayer-Martin (chocolate + VCN

=vancomycin, colistin and nystatin ) are {in isolatinggonococci from heavily contaminated sites e.g.:

Vagina, rectum, & pharynx}.- Colonies: small, smooth, glistening and

semitransparent.



•Biochemical Reactions :

1 - Oxidase positive.

2 - MAIN CHARACTER

↓

produce acid from

glucose maltose.

(√)



•Antigenic Structure and virulence factors:

- Antigenically heterogeneous (>100 serotypes).

- Surface structures subjected to variation in vitro &in vivo to avoid host defences: Virulence factors :

• Pili: mediate resistance to phagocytosis andadherence to epithelial cells .

• Outermembrane proteins:

- attachment of the organism to cells

- the basis for serotyping the gonococci .• Lipoligosaccharide ( LOS) = endotoxin

• IgA protease: split IgA present in mucosalsurface



•Pathogenesis and Clinical Findings:

• Strict human parasite.

• Acute or chronic infection.

• No healthy carriers exist.

• Attacks mucous membranes (genitourinary tract, eye,rectum,throat), → acute suppuration → tissueinvasion, followed by chronic inflammation and

fibrosis (GONORRHOEA)

• M.O.T : sexual intercourse



GONORRHEA is a pyogenic infectious disease affectingthe male and female genital system:

- Urethritis (yellow creamy pus +painful urination)

- Epididymitis and prostatitis (scanty discharge =morning drop)

- Untreated: ↓suppurationfibrosis → urethral strictures.

MALES



- Primary infection: endocervix ,extends to theurethra

and vagina → mucopurulent discharge.

- May then progress to the fallopian tubes (PID).

- Salpingitis →Infertility (20%).

- Chronic gonococcal cervicitis or proctitis

(asymptomatic).

FEMALES



• Gonococcal bacteraemia (=disseminated infection):rare. → skin lesions and suppurative arthritis.

• Gonococcal endocarditis :uncommon severe infection.

• Gonococcal ophthalmia neonatorum:- Infection of the eye of the newborn

- Acquired during passage through an infected birthcanal.- Initial conjunctivitis, if untreated, results inblindness.



• Immunity:

-Repeated gonococcal infections are common.

-Protective immunity to reinfection does notdevelop, because of the antigenic variation ofgonococci.



Laboratory Diagnosis

Specimens

Urethral discharge Urethral ischarge/

cervical secretion

A. During the acute stage

♂ ♀



a) Smears: (2)

- One stained by methylene blue

- The other by Gram stain: Gram-negative diplococciintracellularly in polymorphonuclear leukocytes with

few extracellular organisms.

This is sufficient to diagnose GONORRHOEA



b) Culture:

- Chocolate blood agar (in CO2 at 37C for 48

hours).

- Colonies are identified by:

1) Oxidase test (positive).

2) Gram stained film (Gram negative diplococci).

3) Production of acid from glucose.

4) Coagglutination test using monoclonal antibodies



Culture is done during the acute stage for several reasons:

1. Confirmation.

2. Isolation of the organism (sensitivity to differentantibiotics).

3. Medico-legal purposes.



c) Antigen detection and nucleic acid probe:

- Direct non culture tests.

- For screening specimens where culture facilities arenot available.

ELISA → Ag Gene probe



• Gram stained SMEAR: of no value because

1) The diplococci may be very few in number or totallyabsent

2) presence of secondary bacterial invadors.

CULTURE is necessaryThayer and Martin medium

B. During the chronic stage

♂ Morning urethral drop or prostatic

secretion

♀ Cervical swab

↑CO237C

48 hours

Colonies are identified as mentioned before



• Treatment :

-Penicillins are no longer recommended for the

primary treatment of uncomplicated infection bec. :Both chromosomally and plasmid-mediated resistanceto penicillins is now widespread among strains of N.gonorrhoeae

- Broad-spectrum third generation cephalosporins (ceftriaxone) and fluoroquinolones (ciprofloxacin) maybe used as primary therapy against uncomplicatedgonococcal infections.

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Neisseria Gonorrhea_microb (Lect 22-11)