Unit 1 - Gonorrhea and Chlamydia Flashcards
Neisseria gonorrhoeae bacteriology
G- diplococci with LOS
- human-restricted
- oxidase positive, not encapsulated, needs chocolate agar (not blood agar) as growth inhibited by trace metals and fatty acids
- very sensitive to dehydration, cold
- plasmid-borne Ab resistance is more common than in meningococcus (cephalosporin resistance emerging)
how are N. gonorrhea and N. meningitidis the same and different?
both
- human restricted, G- LOS diplococci
- oxidative positive
- cleared from bloodstream by immune complement
- growth in vitro inhibited by trace metals and FA (need chocolate, not blood, agar)
N. g
- not encapsulated
- hundreds of serotypes
- even more sensitive to dehydration, cold
N. m
-ferment maltose
N. gonorrhea pathogenesis
sexually transmitted or at birth
- genital tract infections most common, anorectal and pharyngeal also occur
- Ab, complement, and neutrophils are restricted to local infection site (vagina, urethra)
- bacteremia occurs in certain strains, predispositions
- extremely contagious sexually (single-exposure transmission)
- symptoms develop quickly (no latency)
what is the usually N. gonorrhea pathogenesis/exam for neonates, males, and females?
neonate: bilateral purulent conjunctivitis; if untreated, permanent blindness
male: usually symptomatic anterior urethritis
female: usually asymptomatic, cervicitis, purulent vaginal discharge, but type IV pili confer “twitching motility” for progression to PID
both: coinfection of pharynx, rectum, eye
virulence factors of N. gonorrhoeae
- IgA protease: clears IgA from mucosal surfaces for colonization
- pili: attach to columnar and transitional epithelium of mucosal surfaces, antiphagocytic
- Opa: opacity-associated proteins enhance cell adherence and entry
- porin A and B channels: in outer membrane, confer serum resistance and enhance cell entry
- LOS: less immunogenic than LOS, but induces local inflammatory response (irritation, discharge, containment)
is N. gonorrhoeae dependent on host for replication?
no, it’s replication-competent, so intracellular penetration is for immune evasion
describe pelvic inflammatory disease
-what is Fitz-Hugh-Curtis syndrome?
spread of cervical infection to fallopian tubes creates pain, risks of infertility, and ectopic pregnancy
- follows from mixing bacteria with refluxed menstrual blood or attachment to sperm (“twitching motility” by pili)
- intermenstrual bleeding, dysurea
- sonogram may show thick fallopian tubes or abscess
- FHCS: bacteria (gonorrhea or chlamydia) jump from tubes to liver capsule to cause acute perihepatis
what happens if bacteremia (dissemination) of N. gonorrhoeae occurs? predisposition?
- lack of urogenital symptoms
- arthritis/dermatitis (joint pain and skin pustules)
- septic asymmetric arthritis (knee common)
- asymmetric tenosynovitis with pain in wrists and akles - rarely meningitis, endocarditis
certain strains are more likely to disseminate
-more common in women, asymptomatic infection, menses, pregnancy, and C6-9 deficiency predispose
how common are gonococcal meningitis and endocarditis? info on them?
both are rare
- meningitis: spinal tap
- endocarditis: EKG, cardio consult (mostly in men)
- -aortic valve more common site
- -subacute onset of fever, chills, sweats, malaise, chest pain, cough
gonorrhea labs for males
urine and exudate testing for PMNs and intracellular diplococci
- if negative: urethral swab for G-, oxidase+, culture on Thayer-Martin agar
- most sensitive and specific method
gonorrhea labs for females
obtain endocervical smear (urethral sample if hysterectomy) but wife exudate off first
-culture on Thayer-Martin
gonorrhea labs for DGI (disseminated gonococcal infection)
- swab, gram stain, culture samples from all affected areas
- blood, joint fluid cultured on nonselective chocolate agar
- immunofluorescence may give better results than G stain or pustule samples
N. gonorrhea treatment
prompt antibiotics, before labs come back
- ceftriaxone, alternate cefixime, cephalosporin
- add azithromycin or doxycycline for coinfection with chlamydia
- aspirate septic joints
- admit if pregnant, PID, DGI, endocarditis, meningitis, purulent joint infection
what is expedited partner treatment?
provides scripts without exam for sexual partners of gonorrhea patients
C. trachomatis bacteriology
elementary bodies: dense, rugged, attach to cell, endocytosed, survive, and “unpack” into reticulate bodies
reticulate bodies: larger, delicate G- membrane, replicate, metabolize, “pack” into EBs, escape host cell
immune response to chlamydia
inflammatory cascade causes swelling and discharge, but fails to clear infection or prevent reinfection
-no useful immune memory, so reinfection common
types of urogenital chlamydia and where most common
18 serovars
A, B, Ba, and C: blinding trachoma (Africa)
L1-L3: lymphogranuloma venereum (Central America)
D-K: genital tract infections (United States)
blinding trachoma
serovars A, B, Ba, C
- leading cause of preventable blindness
- spread by secretions, fomites
- endemic to Africa, S. Asia
- eyelids turn inward, so eyelashes damage cornea
lymphogranuloma venereum
serovars L1-L3
- small ulcer –> painfully swollen lymph nodes near genitals (buboes)
- -aspiration of buboes and fistulas may speed healing
- symptoms from bacterial replication in mononuclear phagocytes of local lymph nodes
- endemic to S. and C. America, rare in US (get detailed travel sex history)
- labwork and treatment the same for other genital chlamydia
“reservoirs” for gonorrhea and chlamydia
gonorrhea is more likely to have symptoms in males, but asymptomatic females are “reservoirs”
the reverse is the case for chlamydia
pathogenesis of genital chlamydia
most commonly local mucosal inflammation and discharge, urethritis, vaginitis, cervicitis
- infection increases risk of getting HIV
- risk of PID; doesn’t go away after treatment of infection
what is Reiter syndrome? symptoms? treatment?
reactive arthritis secondary to immune-mediated response
- conjunctivitis + urethritis + arthritis
- 80% of patients are HLA-B27 positive
- treat with NSAIDs for 6 mo to 2 years until resolved
chlamydia diagnosis exam for female
- easily induced endocervical bleeding
- mucopurulent endocervical discharge
- intermenstrual bleeding
- dysuria
- abdominal pain
chlamydia diagnosis exam for male
- urethral discharge
- urinary frequency and/or urgency
- dysuria
- scrotal pain/tenderness
- perineal fullness
three options for chlamydia diagnosis
- cytologic diagnosis (mostly for infant ocular trachoma)
- stain eye swab with Giemsa or IF - isolation in cell culture
- grows well in many lines, and must ALWAYS do culture if legal implications - detection of chlamydial rRNA by hybridizing to DNA probe
- simpler, less expensive
- more likely to give false positive
why is serology not useful for chlamydia diagnosis?
past infection is too common
chlamydia treatment
- intracellular antibiotics as chlamydia is intracellular
- doxycycline (contraindicated if pregnant or < 9 yo b/c dental problems) or azithromycin
- erythromycin and amoxicillin must be checked for efficacy
- infection can hide “behind” other STDs
