Neisseria gonorrhoeae - Pharos University in Alexandria

Lecture 5 - Fall 2012-2013- (General Microbiology)
MCR 311
Gram -ve Diplococci
Presented by:
Prof. Dr. Mervat El Saygh
Microbiology & Medical Immunology Dept,
Pharos University

LEARNING OBJECTIVES
• State the characteristics of the 2 types
of Neisseria
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BACTERIA
Staphylococci
Streptococci
Enterococci
G+ cocci
COCCI BACILLI SPIROCHETES
Non spore-forming
G+ bacilli
Spore forming
G+ bacilli
Enterobacteriaceae
Treponema
Borrelia
G- diplococci
Pseudomonas/Vibrio
Campylobacter
Helicobacter
Mycobacteria
(TB/Leprae)
Parvobacteriaceae
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NEISSERIA
• aerobic,
• gram negative diplococci
• require carbon dioxide for growth,
• grow at 37°C,
• grow best on media containing blood
(blood agar and chocolate agar).
• They are oxidase positive.
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Neisseria Meningitidis

Neisseria Meningitidis
– causative agent of meningococcal
meningitis in adults
– spread by respiratory route.
– is divided into 13 serogroups according to
the capsular polysaccharide.
– Serogroups A, B, C, Y, and W-135 are the
most important.
– Clinical picture: Rapid onset with
headache, fever and neck stiffness
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Neisseria Meningitidis - Clinical
Manifestations
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• Begins as mild pharyngitis with occasional slight fever.
• Initial signs are fever, vomiting, headache, and stiff
neck.
• A petechial eruption then develops that progress form
erythematous macules to frank purpura; vasculitic
purpura is the hallmark.
• LPS of organisms causes intravascular coagulation,
circulatory collapse, and shock.
• Waterhouse-Friderichsen syndrome describes fulminating
meningococcemia with hemorrhage, circulatory failure,
and adrenal insufficiency.

Neisseria Meningitidis – Laboratory
Diagnosis
• Direct CSF examination and Gram
stain reveals gram negative diplococci
intra and extra cellular
• culture on blood agar or chocolate
agar
• oxidase positive
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Neisseria Meningitidis – Control
Prevention
• Provide penicillin prophylaxis for exposed young family
children; if patient in day care setting with other young
children, also give penicillin; no prophylaxis for older children
or adults.
• Give rifampin to all family members and to patient to eradicate
the carrier state (Penicillin will not eradicate carrier state).
• Vaccine is capsular polysaccharide from A and C serogroups
(B serogroup polysaccharide is poorly immunogenic); biggest
problem is vaccine failure in target group aged 6 months to 2
years where most infections occur.
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Neisseria Meningitidis – Virulence
Attributes
• Capsular polysaccharide inhibits phagocytosis.
• LPS causes extensive tissue necrosis, circulatory
collapse, intravascular coagulation, and shock.
• IgAase degrades IgA; probably important because
these infections begin on mucosal membranes
(streptococci, hemophilu, and neisseria have this
enzyme).
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N. meningitidis
(the “Meningococcus")
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Capsule
• capsule
– inhibit phagocytosis
• anti-capsular antibodies
– stop infection
•antigenic variation
– sero-groups
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• vaccine
–multiple sero-groups

Neisseria Gonorrhoeae

Neisseria Gonorrhea
• Causative agent of gonorrhea (sexually
transmitted disease).
• It attacks the mucous membrane of the
genito-urinary tract, eyes and the
rectum producing acute suppuration,
chronic inflammation and fibrosis.
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Neisseria Gonorrhea
• In male it causes gonococcal
uretheritis
• In female usually asymptomatic, found
in the female cervix
• Neonatal ophthalmia in those born to
infected mothers
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Neisseria Gonorrhoeae
Classification
N. gonorrhea differentiated by auxotyping
(nutritional requirements) or colonial morphology
(types 1 and 2 are virulent, types 3, 4 and 5 are far
less virulent).
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NEISSERIA
Neisseria 23/10/2012 gonorrhoeae
18

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Neisseria Gonorrhoeae - Clinical
Manifestations
• Mucous membrane infections that occur predominantly in
anterior urogenital tract.
• Asymptomatic infection in 20% to 80% of females and 10% of
males, these patients transmit the bacteria to consorts,
resulting in symptomatic gonorrhea.
• A number of different types of infection:
A- Urethirtis- thick, yellow, purulent exudates containing bacteria
and numerous PMNs; painful and frequent urination; meatus may
be erythematous.
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B- Complications of urethritis include epididymitis and prostatitis in
males and pelvic inflammatory disease in females; repeated
infections may cause scarring with subsequent sterility in both
sexes.

Neisseria Gonorrhoeae - Clinical
Manifestations (Cont’d)
C- Rectal infections- painful defecation, discharge, constipation,
pretties; prevalent in gay males.
D- Pharyngitis- mild form mimics viral sore throat; severe form
mimics streptococcal sore throat; purulent discharge.
E- Disseminated infection- bloodstream invasion in which organisms
initially localize in skin causing dermatitis (single macular,
popular, erythematous lesion); a few days later, organisms
spread to the joint causing overt, painful arthritis (hands, wrists,
elbows, ankles).
F- Infant eye infection- ophthalmic neonatorum involve sever,
bilateral purulent through birth canal.
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Neisseria Gonorrhoeae – Laboratory
Diagnosis
Clinical Specimens
• On females, always do a genital and a rectal
culture.
• If using a speculum or endoscope, do not use a
lubricant because it will kill organisms.
• Organisms are labile, and specimens should be
immediately.
• If disseminated gonorrhea, culture blood and
synovial fluid; culture of skin lesion is rarely
successful.
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Neisseria Gonorrhoeae – Laboratory
Diagnosis
In acute infection:
• Direct smear of the discharge stained
by gram stain revealed gram negative
diplococci intra and extracellular in pus
cells.
• cultured on chocolate agar.
• Oxidase positive
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Neisseria Gonorrhoeae – Laboratory
Diagnosis
In chronic infection:
• In male: morning drop
• In female: endocervical swab
• Culture on Thayer-Martin agar
(selective media)
• Blood culture in disseminated cases
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Neisseria Gonorrhoeae – Control
Prevention
• Treat partners because of contagious nature of
gonorrhea.
• To prevent newborn gonococcal conjunctivitis, use
topical AgNo 3 or tetracycline; antibiotic is better because
it will also kill Chlamydia trachomatis if present.
• Use condom to prevent transmission.
• Identify asymptomatic patients by culturing gonococci,
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and treat with penicillin.

Neisseria Gonorrhoeae – Virulence
Attributes
• IgAse that degrades IAg1; important because in
mucosal infections, this antibody probably plays a
key early role (IgAse also in hemphiuls and
streptococcal organisms).
• Plasmid that codes for penicillinase production.
• Pili are protein surface appendages that mediate
gonococcal attachment to mucosal epithelium.
• Lipopolysacchride (LPS) damages mucosal cells.
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Neisseria Gonorrhea
In male it causes gonococcal uretheritis
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Enterococci
On blood agar they form colonies of variable hemolysis.
They are heat resistant (40°C)
They cause nosocomial infections in hospitals.
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MRSA
are strains of staphylococci which are considered resistant
to all beta lactam antibiotics including penicillins
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Streptococci
Streptococci
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Beta-hemolysis
a clear zone of hemolysis on blood agar
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Neisseria
gram negative diplococci
require carbon dioxide for growth
Oxidase positive
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Coagulase negative
staph
Staphylococcus epidermidis and staphylococcus
saprophyticus
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Neisseria meninigitidis
Causes meningitis in adults
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Enterotoxin
A toxin that causes food poisoning
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Thayer-Martin
Selective media for neisseria
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Viridans Streptococci
cause subacute bacterial endocarditis of abnormal heart
valves.
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Thank You