Microbiology Lecture 3. Flashcards
N. gonorrhoeae bacteriology
gram - (LOS instead of LPS); oxidase +; chocolate agar; not encapsulated; hundreds of serotypes (no vaccine); sensitive to dehydration and cold; ab resistance sometimes
What is LOS and what bacteria is it found on?
LOS - similar to LPS but NOT as immunogenic - much shorter chain; found on n. gonorrhoeae
How is n. gonorrhoeae transmitted?
sexually or at birth
What virulence factors does n. gonorrhoeae have?
pili (attach to columnar and transitional epithelium - antiphagocytic), IgA protease (clear mucosal antibody), Opa (causes blindness), LOS, porins
Can n. gonorrhoeae replicate on its own?
YES - intracellular for immune evasion
What does immune reaction to LOS cause?
irritation, dischar, containment
What are Porin A and B?
anti-complement found in n. gonorrhoeae - confer serum resistnace in strains that are more likely to disseminate
How does host typically defend against n. gonorrhoeae?
IgG enhanced complement and PMNs
Symptoms of n. gonorrhoeae
males: usually symptomatic with anterior urethritis females: often asymptomatic: cervictis, type IV pili confer “twitching motility” -> progression to PID neonate: purulent conjunctivitis which may cause blindness
Immune response to n. gonorrhoeae
antibodies, complement, neutrophils may restrict infection to local site
Symptoms of disseminated infection of n. gonorrhoeae
lack of urogenital symptoms, arthritis/dermatitis (most common), septic arthritis, rarely meningitis, endocarditis
What you might see on exam of patient with n. gonorrhoeae
male: urethritis, dysuria, purulent discharge female: purulent vaginal discharge, PID if not treated
Symptoms of PID
lower abdominal pain, vaginal discharge, dysuria, tenderness, intermenstral bleeding
lab work for n. gonorrhoeae
can’t grow on blood agar - need Thayer Martin for normal flora or chocolate if already sterile (blood CSF) male: urine and exudate for PMNs and intracellular diplococci (microscopy common, NAAT preferred) female: obtain endocervical smear for NAAT, culture on Tayer Martin (tricky for males) disseminated gonococcal infection: gram-stain, NAAT, culture samples from all affected areas
3 similarities between meningitis and gonorrhoeae
- IgA protease 2. septic arthritis 3. growth on thayer-martin medium
treatment for n. gonorrhoeae
antibiotics begin BEFORE labs come back (ceftriaxone, alternate cefixime, cephalosporin), add azithromycin or doxycycline for confection with chlamydia; aspirate septic joints; admit if pregnant, PID, DGI, endocarditis, meningitis, purulent joint infection
Bacteriology c. trachomatis
chlamydia: unique life cycle of elementary bodies (infectious, live outside, don’t multiply) and reticulate bodies (larger, delicate, replicate, metabolize, pack into EBS)
What is a known virulence factor of c. trachomatis?
T3SS - used for entry and establishing inclusion body
Serovars A,B, Ba, C of c. trachomatis
blinding trachoma - leading cause of preventable blindness, spread by secretions, fomites - endemic to africa and southern asia
Serovars L1-L3
lymphogranuloma venereum (LV) - small ulcer proceeds to painfully swollen lymph nodes near genitals - sexually transmitted - south and central america
Serovar D-K
genital chlamydia - most common STD - asymptomatic - lesions help HIV transmission
Diagnosis of c. trachomatis
blinding: eyelashes turned inward; LG buboes, histor of sex while traveling; genital history of being a slut
Exam for c. trachomatis
female: mucopurulent endocervical discharge, bleeding, dyuria, abdominal pain, progression to PID Male: urethral discharge, dysuria, scrotal pain both: risk of reiter syndrome = reactive arthritis
lab for c. trachomatis
infant occular trachoma: swab eye, microscopy stained with giemsa or IF for chlamydial inclusions; tissue culture; NAAT preferred
Treatment for c. trachomatis
antibiotics - ones that can penetrate infected cell membranes though: doxyclcine or azithromycin. if allergic, pregnant, or child then erythromycin+amoxicillin
pathogenesis of trichomoniasis
growth of organism can cause genital irritation, which increases risk of other STIs
diagnosis of trichomoniasis
female: frothy yellow-green vaginal discharge, PID - colposcopy: colitis mascularis or “strawberry cervix” male: urethritis, prostatitis
lab of trichomoniasis
light microscopy, whip test and culture (not sensitive) so NAAT
treatment for trichomoniasis
oral metronidazole
pathogenesis of bacterial vaginosis
loss of balance among vaginal normal flora leads to irritation - balance thrown off due to antibiotics, douching, menopause, frequent sex, bubble baths
diagnosis of bacterial vaginosis
vaginal irritation, odor, discharge
lab for bacterial vaginosis
microscopy: thin, gray, homogenous discharge, “clue cells” are squamous epithelium covered in gardnerella; whiff test; elevated vaginal pH
treatment for bacterial vaginosis
metronidazole or clindamycin
chancroid bacteriology
haemophilus ducreyi: small, gram -, facultative anaerobic bacillus
chancroid pathogenesis
asia, africa, caribbean - painful genital swellings, softer than syphilis cancre, may reach lymph node like LV
chancroid diagnosis
men: multiple painful genital ulcers with yellow-gray exudate women: often asymptomatic - can be same
chancroid treatment
drain the lesions, oral azithromycin, ceftriaxone, ciprofloxacin - could have antibiotic resistance
