Lab Nine :-
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Medical Microbiology
Prepared by: Luma J. Witwit
Neisseria
The family Neisseriaceae includes Neisseria species and Moraxella
catarrhalis as well as Acinetobacter and Kingella and other Moraxella
species.
General characteristics:
Gram – negative diplococci , Kidney bean shape, non motile, non
spore forming bacteria.
- They are oxidase positive and catalase positive.
- Meningococcus and Gonococcus need 5-10% CO2 and humid
atmosphere and require chocolate agar to grow on.
- The genus Neisseria include two important human pathogens:1- Neisseria gonorrhoeae (gonococci) infect the genital tract.
2-Neisseria meningitidis (meningococci) infect the CNS causing
meningitis.
Neisseria gonorrhoae ( G C )
Diseases :
Females : cervicitis , endometeriosis, urethritis, STD, pharyngitis
and proctitis.
Male : urethritis , prostatitis , per urethral – abscess pharyngitis,
proctitis. Females and males: disseminated gonococcal infection
Newborns conjunctivitis .
Laboratory diagnosis
 Discharge are collected:In the male: from the urethral discharge ( morning drops ) , exudates
or made from the centrifuged urinary deposit, conjunctiva swab.
In the female: from vagina to the cervix and fallopian tubes swab.
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Lab Nine :-
________________
Medical Microbiology
Prepared by: Luma J. Witwit
Gram stain :A direct Gram stain of urethra, cervix, rectum, conjunctival smears
reveal
*In male: sensitivity about 90%.
*In female: sensitivity about 50% is due to the presence of normal
flora in female urogenital tract.
Gram stain of urethral exudate of a patient with gonorrhoea.
Intracellular (within polymorphonuclear leukocytes) gram – negative
diplococcic(Neisseria gonorrhoae) in clump are marked by the small
arrows are diagnostic.
*Culture of urethral exudates from male are not necessary when
the stain is positive, but the cultures should be done for female.
 Specimen choice and collection:The specimen choice and collection method depends on the testing
technique used in a laboratory and the age, sex and sexual orientation of
the patient. Specimens should be collected with Dacron or rayon swabs
because calcium alginate may be toxic to gonococci. Fatty acids
inhibit the growth of gonococci; therefore, cotton swabs that do not list
acceptable manufacturer specifications should not be used. To minimize
the inhibitory effects of unknown substances in the specimen, the swabs
should be inoculated directly onto growth medium or placed in swab
transport medium immediately.
Transport of specimens:-
Methods of transportation vary with the specimen and the type of
test being done, but in all instances when commercially available
transport systems are used, the instructions provided by the manufacturer
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Lab Nine :-
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Medical Microbiology
Prepared by: Luma J. Witwit
should be followed. Amies or Stuart madia are used as transportation
media.
Culture
The primary specimens should be inoculated into nonselective
chocolate agar and selective agar containing antimicrobial agents that
inhibit the growth of commensal bacteria and fungi. The antibacterial
agents in modified Thayer-Martin, Martin Lewis and New York City
medium are vancomycin, colistin, trimethoprim lactate and the antifungal
agents nystatin and neomycin or amphotericin B.
 After 48 hours Gonococci and meningococci from convex,
glistening, elevated, mucoid colonies 1-5mm in diameter. Colonies
are transparent or opaque, nonpigmented, and nonhemolytic.
 Neisseria flavescens, N. subflava, and N. lactamica have yellow
pigmentation.
 N. sica produces opaque, brittle, wrinkled colonies.
 Moraxella catarhalis produces nonpigmented or pinkish- gray
opaque colonies.
Nucleic Acid Amplification Test:Detection of Gonococcal nucleic acid which causing DNA prob
which can detect nucleic acid of microorganism.
Serology;Serum and genital fluid contain IgG and IgA antibodies against
gonococcal pilli, outer membrane proteins, and LPS. Some IgM of
human sera is bactericidal for gonococci in vitro.
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Lab Nine :-
________________
Medical Microbiology
Prepared by: Luma J. Witwit
Carbohydrate fermentation(N. gonorrhoae):Gonococcus is glucose fermenter and positive for hydroxyproline
aminopeptidase . Surface structures include the following :
1- Surface structures include the following:
A)
Pili
B)
3 Types of protein(POR,OPA,RMP)which important
for adhesion.
2- Protease: is a major mucosal immunoglobulin of humans.
Neisseria meningitides:
The species have some of important virulence factors such as:
1- Antiphagocytic polysaccharide capsule .
2- Pilli ( colonization and antiphagocytic factor) .
3- Protease .
Disease:Meningitis, Urethritis , Proctitis . Meningococcus is a common cause of
meningitis in children (3 months to1 year old). and among young adult .
Laboratory diagnosis:
Meningococcus can ferment glucose and maltose sugar and it is
positive for Y-glutamyl aminopeptidase .
Other Neisseria sp.
Neisseria sicca , Neisseria subfolava , N. flavescens , N. mucosa.
They are part of the normal respiratory flora.
N. catarrhalis ( Moraxella catarrhalis )
Disease:Bronchitis, pneumonia , sinusitis , conjunctivitis , meningitis . otitis
media, female genital tract infection.
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Lab Nine :-
________________
Medical Microbiology
Prepared by: Luma J. Witwit
Laboratory diagnosis:-
Catalase and oxidase: positive.
Negative for all carbohydrates: asaccharolytic.
Negative for all enzymes.
Biochemical test N.gonorrhoea
Glucose
Maltose
Lactose
Hydroxyproline
aminopeptidase
Ү-glutamyl
aminopeptidase
N. meningitidis
N. catarrhalis
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