Flashcards in Neisseria gonorrhoeae Deck (24)
What are the pathogens species in family Neisseriaceae?
N. gonorrhoeae, N. meningitidis, Moraxella catarrhalis
What is the gram staining and morphology of Neisseria and Moraxella?
Gram-negative diplococci. Single cocci are kidney-shaped, flat on one side.
What environment is required for culturing Neisseria and Moraxella (media, gasses, temp, pH)?
Rapid autolysis occurs at 25C and alkaline pH.
What allows for repeated infections gonorrhoeae infections?
N. gonorrhoeae is antigenically very heterogeneous and capable of changing its surface structures (antigenic variation and phase variation) to avoid host defenses. Because there is so much antigenic variation by N. gonorrhoeae a single person can be infected with N. gonorrhoeae many times (>10X) in their lifetime.
What are pili used for, and how does Neisseria use them to evade host defenses?
Pili are important for attachment to the mucosal epithelium. There are hundreds antigenic types of pili (called - antigenic variation). In addition, the bacteria are capable of switching on and off the expression of pili (called - phase variation).
What are Opa proteins?
Opa proteins are outer membrane proteins. N. gonorrhoeae colonies can either be transparent, opaque, or mixed depending on the presence of Opa proteins at the bacterial surface. Opa proteins are important for attachment and may influence the site and type of infection.
What is LOS and what does it cause?
Lipo-oligosaccharide (LOS) is the equivalent of the lipopolysaccharide (LPS) of gram-negative bacteria, but without the long O-side chains. There are eight or more types of LOS. LOS is toxic for ciliated cells in tissue cultures. LOS is probably responsible for many of the inflammatory processes seen during an infection.
What sort of protease does Neisseriaceae possess that helps it evade host defenses?
IgA protease cleaves the Fc portion of human IgA, preventing opsonized bacteria to become phagocytosed.
What are the four surface structures that Neisseriaceae uses to evade host defenses?
Pili - 100's of types = antigenic variation, & phase variation
LOS - 8+ types, toxic to ciliated cells, likely inflammatory
IgA protease - cleaves Fc portion of IgA
Who are more likely to be asymptomatic carriers of gonorrhoeae and what condition may this lead to?
The prevalence of asymptomatic carriers is much greater among women. Asymptomatic carriers are a major problem in the control of gonorrhea and asymptomatic infection particularly in women can lead to a more serious infections (e.g. pelvic inflammatory disease).
What should be suspected in a case of gonorrhoeae infection in a pre-pubescent?
Sexual abuse is the most frequent cause of gonococcal infection in preadolescent children. Gonococcal infection in children should immediately suggest child abuse and be further investigated by contacting police and social workers.
What are the common clinical manifestations of gonorrhoeae infection in the lower tract?
2. Abscess formation in glands adjacent to the vagina
What are the common clinical manifestations of gonorrhoeae infection in the upper tract?
2. Pelvic inflammatory disease (in at least 15% of cases) More likely to occur in women with recent asymptomatic infection.
What are the common clinical manifestations of localized gonorrhoeae infection outside the urogenital system?
1. Proctitis – more frequently found in homosexual men.
2. Pharyngitis (in 20% of infected homosexual men or heterosexual women)
3. Ophthalmia neonatorum (bilateral conjunctivitis in infants born of infected mothers)
4. Peritonitis and perihepatitis
What are the common clinical manifestations of systemic gonorrhea infection?
1. Dermatitis-arthritis-tenosynovitis syndrome
2. Monoarticular septic arthritis
3. Endocarditis (rare)
4. Meningitis (rare)
How is the risk of HIV infection increased by a gonorrhea infection?
In persons who are not infected with HIV, the same inflammatory cells elicited by gonococcal infection provide a ready target for HIV infection; thus, risk of HIV acquisition is very likely increased in this setting.
What will gram staining of exudates reveal in a gonorrhea infection?
Gram stained smears of urethral or endocervical exudates reveal many diplococci WITHIN polymorphonuclear cells (PMNs). This is true only for urogenital infections with N. gonorrhoeae. It is NOT true for other kinds of infection (e.g. oral pharyngeal infections).
What is the sensitivity and specificity of gram staining of exudates in a gonorrhea infection for men and for women?
Sensitivity: 90% for men, 50% for women. Specificity: 99% for men, 90% for women.
What is the current recommended antibiotic treatment for gonorrhea infection?
Ceftriazone, single dose IM (250mg) plus
Azithromycin, single dose oral (1 gram) or
Doxycycline, 2X daily for 7 days oral (100mg)
Affect different targets simultaneously
What other infection should be suspected and treated with any gonorrhea infection?
Patients infected with one are often infected with the other
The cost of treating for both is less than the cost of testing.
Azithromycin also treats C trachomatis
What is the prophylactic treatment given at birth for ocular infection in infants born from infected mothers?
1% silver nitrate solution,
PS: The efficacy of these preparations in preventing chlamydial ophthalmia is less clear, and they do not eliminate nasopharyngeal colonization by C. trachomatis.
What is the treatment of ocular infection with N. gonnorheae?
Ceftriaxone (IV or IM, single dose). Topical antibiotic alone is inadequate.
What is the treatment of ocular infection with C. trachoma's?
Erythromycin (orally, 10-14 days). Topical antibiotic alone is inadequate.