Neisser ia Dr Salma Pyogenic cocci Neisseriae Characters

Neisser ia Dr. Salma

Pyogenic cocci Neisseriae : Characters: Gram—negative diplococci , individual cocci are kidney – shaped , non motile non hemolytic and non pigmented , Colonies are opaque or transparent. There are two pathogenic species for humans : 1. Neisseria gonorrhoeae(Gonococci) GC, the causative agent of gonorrhea, neonatal conjunctivitis (ophthalmia neonatorum)and pelvic inflammatory disease(PID). 2. Neisseria meningitidis (Meningococci)MC, the causative agent of meningitis and meningococcemia.

General Characters of the Genus 1. Gram-negative diplococci

• The growth of both organisms(GC and MC) is inhibited by toxic trace metals and fatty acids found in certain culture media e. g. , blood agar plate , they are therefore culture on chocolat agar containing blood heated to 800 C. • The organisms are rapidly killed by drying , sunlight , moist heat and many disinfectants. (they are fastidious). • Non pathogenic e. g. Moraxella catarrhalis was previously named Branhamella catarrhalis (Neisseria catarrhalis).

N. gonorrhoeae. Morphology. Culture characters: - Enriched media: Chocolate agar - Selective media: Modified Thayer Martin (Chocolate agar + antibiotics). 5 -10% CO 2

Neisseria gonorrhoeae (Gonococci) GC. Classification : On the basis of morphology and their colonial mutation , there are four biotypes : (T 1, T 2) virulent small brown colonies (pilitated gonococci) posses pili which are adherence factors. (T 3, T 4)a virulent large non pigmented colonies (no pilitated gonococci).

Virulence factors (antigenic structure): 1. pili acts as adhesions. 2. porprotien. 3. Opa proteins. 4. Rmp(protein 111). 5. lipopolysaccharide(in gonococci is called a lipooligosaccharide , LOS, as endotoxin). 6. IGA 1 protease.

Pathogenesis : • Gonococci cause-- gonorrhea (sexually transmitted disease STD or veneral disease) -Ophthalemia neonatorum. • Gonorrhea (example urithritis, cervicitis) • Gonorrhea is usually symptomatic in men but often asymptomatic in women. • Gonococci are sexually transmitted. The transmission of these bacteria is through direct contact of mucous membrane to mucous membrane , usually sexually contact ; mother-to-neonate during birth. • GC attack mucous membrane of genitourinary tract , eye , rectum and throat

Gonococci caused both localized infection in the genital tract and disseminated infections with seeding of organs, GC reach these organs via the bloodstream(gonococcal bacteremia). gonorrhea - In men is characterized primarily by urethritis accompanied by dysuria(painful urination) and purulent discharge complication include(Epididymitis and prostatis). -In women cervicitis and the most frequent complication is an ascending infection of the uterine tubes(salpingitis , PID)which can be result in sterility and ectopic pregnancy as a result of scarring of the tubes.

Gonorrhoeae Urethral discharge Cervical Discharge

Neonatal Conjunctivitis

In newborn infant GC. Can cause ophthalemia neonatorum , an infection of the eye of the newborn is acquired from the mother during passage throug an infected birth canal. Other sexually transmitted infections , example, syphilis and non gonococcal urithritis (NGU) cause by Chlamydia trachomatis , can coexist with gonorrhea therefore appropriate diagnostic and therapeutic measures must be taken.

Lab. Diagnosis: 1. Specimens , pus , secretion from urethra , cervix , conjunctiva , throat and rectum. 2. Gram stained smear, then we look intracellular Gram— negative diplococci in PMNs(polymorphoneuclear cells) from urethral discharge in men is sufficient for diagnosis while in women false positive because of the normal flora interference. 3. Culture , on A. Chocolate agar.

B. Gram-stained smear ØIn men: Intracellular Gram-negative diplococci (diagnostic) ØIn women: Less sensitive

b. Thayer-Martin agar. (selective medium) which is chocolate agar containing antibiotics (vancomycin , colistin and nystatin ) to suppress the normal flora found in the specimen. c. Modified Thayer-Martin agar. same as(Thayer –Martin agar plus trimethoprim) The culture is incubated in an atomosphere containing 5% CO 2 (candle extinction jar)at 370 C. 4. Oxidase test positive. 5. Sugar fermentation the differentiation between GC and MC is made on the bases of sugar fermentation, GC ferment glucose but not maltose while MC ferment both glucose and maltose. 6. Nucleic acid amplification test.

C. Cultivation:

D. Identification: v Identification at the genus level Gram –ve diplococci Oxidase +ve

v Identification at the species level • Glucose utilization Glucose • Nucleic acid probe Maltose

Treatment Ceftriaxon plus doxycyclin. Some strain of GC called penicilinase producing gonorrheae or(PPNG) possess plasmids containing the gene for penicilinase prodaction(resistant to penicillin

Control and prevention : Treatment of symptomatic patient with contact, cases on gonorrhea must be reported to the public health department to ensure proper follow up. Gonococci conjunctivitis is preventive by the use of erythromycin ointment. Silver nitrate drops are use less frequently. No vaccine is available.

Neisseria meningitidis (meningococcal) At least 13 serologic groups on the basis of the antigencity of their capsular polysaccharide (A, B, C, D, X, Y, Z, W 135, 29 E, 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 bacterial meningitis in persons over 2 months of age: Streptococcus pneumonia and Neisseria meningitides of these organisms, MC in group (A) cause epidemics of meningitis. Virulence Factors (antigenic structures) : Meningococci have three virulence factors: a- polysaccharide capsule which act antiphagocytic factor. b- Endotoxins (LPS) which cause fever , shock. c- Ig. A 1 protease cleaves secretary Ig. A

Pathogenesis and clinical finding: Disease meningitis and meningococcemia, MC spread via respiratory secretion, MC via nasopharynx – blood stream- bacteremia (meningococcemia intravascular coagulation and spread-meningitis most common complication of meningococcemia – fulminate meningococcemia (septic shock). Meningitis most common disease in children less than 1 year.

Diseases caused by N. meningitidis in the nasopharynx in 5 - 30% 1. Meningitis 2. Meningococcemia Skin rash

. Lab. Diagnosis: - 1. Specimens from blood, CSF and nasopharyngeal swap. 2. Direct-Gram stain smear of centrifuged CSF shows MC as typical Neisseria with in polymorph nuclear leukocyte or extracellularly. 3. Culture CSF specimen are plated on Chocolate agar and incubated at 37 c with 5% CO 2. also culturing in Thayer martin agar and modified TM. 4. Biochemical test: --Oxide 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.

N. meningitidis • Morphology: same + capsule • Culture characters: 1. It grows on chocolate & MTM 2. It can also grow on blood agar • Biochemical reactions: . Oxidase positive. . Utilization of glucose and maltose (acid only) Glucose Maltose

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 close 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 penicillin It produces butyrate esterase.

Gonococci (GC) Meningococci (MC) Non capsulated Contain plasmid Rare Present in genital tract Present in upper respiratory tract Cause sexually transmitted Cause meningitis Maltose fermentation negative Maltose fermentation positive Vaccine not available Vaccine available

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