Flashcards in Micro: Gonorrhea and Chlamydia Deck (34)
What is the epidemiology of urethritis/cervicitis in the US?
humans only known host for G & C
both more common in people <25
rates of C continue to rise, G stable to slight decrease
What are the general features of NG?
meningitides (encapsulated) and gonorrhaeoe (unencapsulated)
gram negative diplo
catalase and oxidase positive, glucose oxidation
needs CO2 and 35-37 degrees for growth
grow on chocolate agar
What are the major antigens of NG?
LOS = lipooligosaccharide
OMPs (porins, opa and rmp)
How is NG transmitted?
person to person - usually sexual
able to bind sperm
What are the pili on NG?
composed of subunits of pilin
phase and antigenically variable (limit vaccine)
required for attachment to host cell, no inf w/o it
inhibit phagocytosis by PMNs
What are the porins on NG?
PorA and PorB (more prominent)
fxn in adhesion and invasion
form transmembrane channels
inhibit neutrophil degranulation by preventing phagolysosome fusion
immune evasion due to variability
What do opa and rmp do on NG?
opa: phase variable, adherence, stimulate endocytosis for invasion
rmp: binds non-complement fixing antibodies, blocks deposition of complement-fixing abs, antibactericidal
What is LOS?
lipid a and oligosaccharide (not LPS - no O antigen)
endotoxic to urethral and fallopian tube epithelial cells
frequent antigenic variation - target for bactericidal abs in serum
What are minor virulence factors of NG?
IgA1 protease - limits mucosal resistance
transferrin binding proteins - iron scavengers
natural competence - can pick up DNA from environment for variability
What is the immune response to reinfection w NG?
Ab response - targets pili, opa, LOS
anti LOS Ab trigger complement --> neutrophil chemotaxis
complement helps prevent dissemination
sialylation of LOS - makes antigen, prevents recognition by Factor H, inhibits complement activation by alternative pathway
What is the pathogenesis of NG?
bacteria attach to and invade mucosal cells, evades immune system
can replicate in columnar epithelium or inside phagocytic vacuoles
LOS causes release of inflammatory cytokines (TNFalpha) --> symptoms
some asymptomatic, mucosa w/o invasion
What are the primary manifestations of NG?
disseminated - arthritis dermatitis syndrome (asymmetric joint involvement, papules)
How is NG diagnosed?
*nucleic acid amplification tests: PCR, TMA - can't be used in child sex abuse cases
What are the resistance mechanisms of NG?
plasmid mediated: penicillin, tetracycline
chromosomally mediated: penicillin, tetracycline, cephalosporins, spectinomycin, fluoroquinolones
What is the current treatment for uncomplicated NG?
IM ceftriaxone plus doxycycline or azithromycin
*cefixime PO is no longer second line
What is the current treatment for disseminated NG?
daily IV ceftriaxone
with improvement can switch to oral cefixime BID
What is the prevention of NG?
no vaccine - identify and treat affected individuals
What are the general features of CT?
obligate intracellular --> no gram stain
difficult to grow - embryonated eggs or tissue cell cultures
restricted to infecting nonciliated columnar, cuboidal and transitional epithelial cells
2 biovars, 19 serovars (variable coding for MOMP)
What is the unique life cycle of CT?
elementary body (EB): metabolically inactive but infectious, what flies around and infects
reticulate body (RB): metabolically active but non-infectious, what replicates inside cells
How is CT transmitted?
contact w infected person - inf doesn't confer immunity
asymptomatic is common
What syndromes are associated with CT?
urogenital: non-gonococcal urethritis, prostitis
lymphogranuloma venereum (LGV)
infant pneumonia (afebrile, diffuse interstitial --> rhinitis and cough)
What are the details of the urogenital dz seen with CT?
males: half asymptomatic, w gonococcal inf common, serovar D-K
females: lots asymptomatic, infertility, progression to PID, serovar D-K
proctitis: rectal LGV making a comeback (L1-L3)
What is LGV?
first - small *painless genital ulcer
next - painful inguinal lymphadenopathy, Groove sign, can rupture
sequelae = scarring and strictures
What is trachoma?
leading cause of preventable blindness
transmission via droplets, hands, clothing, flies
eyelashes turn inward and abrade cornea
repeat inf - no immunity
What is Reiter's syndrome?
reactive arthritis - seronegative
often HLA B27 positive
classic triad: arthritis, urethritis, conjunctivitis
How is CT diagnosed?
cultures is specific but difficult
gram stain can rule out gonorrhea
cytology - Giemsa stains for inclusion - insensitive
Ag detection - DFA, ELISA
nucleic acid tests - most sensitive, doesn't distinguish serovars
serology - mainly for LGV
What is the treatment for CT?
adult genital inf: 1 dose azithromycin, doxycycline for 7 days
neonatal conjunctivitis: oral erythromycin/14 days
LGV: doxycycline/21 days
What are the features of mycoplasma and ureaplasma?
lack cell walls
cause NGU, PID, cervicitis
difficult to diagnose - molecular tests being developed
treatment is same as chlamydia
What is the diagnosis and treatment of candida?
clinical exam, wet prep, KOH
topical azoles, fluconazole
What are the features and syndromes of trichomonas vaginalis?
flagellated, unicellular protozoan
vaginal discharge, urethritis, prostatitis, men may be reservoir
What is the diagnosis and treatment of trichomonas vaginalis?
wet mount and molecular detection, motility required for diagnosis
imidazoles - metronidazole, tinidazole
What is bacterial vaginosis and what does it cause?
polymicrobial anaerobes but associated with gardnerella vaginalis
sexually associated but not transmitted
causes malodorous discharge
How is bacterial vaginosis diagnosed?
Gram stain - variable staining
Clinical/Amsel's criteria: discharge, pH>4.5, clue cells (vaginal epithelial cells studded w incoherent coccobacilli) on wet prep, amine odor w KOH (whiff test)