Gonorrhea and Chlamydia Flashcards
1
Q
Bacteriology of N. gonorrhoeae
A
- gram (-) diplococci
- human-restricted
- diplococci
- oxidase positive
- won’t grow on blood agar, use chocolate agar or Thayer- Martin as appropriate
- cleared from bloodstream by immune complement: complement deficiencies are predisposing for complications
- NOT encapsulated
- hundreds of serotypes
- very sensitive to dehydration, cold
- plasmid-borne Ab resistance more common than in meningococcus, cephalosporin resistance emerging right now
- gram negative LOS
2
Q
Transmission of N. gonorrhoaea
A
- transmitted sexually or at birth
- Pili, IgA protease, and Opa virulence factors for attachment to mucosal surfaces and intracellular penetration
- bacterium IS replication-competent, so intracellular penetration is probably for immune evasion
- local immune reaction to endotoxin LOS causes irritation, discharge, containment
- porin A and B confer serum resistence in strains that are more likely to disseminate (Disseminated Gonococcal infection)
- male: usually symptomatic: anterior urethritis
- female: often asymptomatic: cervicitis, Type IV pili confer “twitching motility -> progression to PID, genital tract infections most common, anorectal and pharyngeal also occur
- neonate: purulent conjunctivitis
3
Q
Pathogenesis of Gonorrhaea
A
- transmitted sexually or at birth
- antibodies, complement, neutrophils restrict infection to local site
- bacteremia can occur in certain strains, predispositions
- extremely contagious sexually (single exposure transmission)
- symptoms develop quickly (no latency)
- infection in children is a reportable marker for sexual abuse
- 700k new infections
- most common in African Americans, rural Southeast, inner cities, young unmarried, low education (socioecomic factors)
- infection rates crashed in 1970s but have been creeping upward more recently
4
Q
Diagnosis of Gonorrhea - Exam
A
- male- urethritis, dysuria, purulent discharge
- female- purulent vaginal discharge, PID- pain, bleeding, perihepatitis, thick Fallopian tubes or abscess on sonogram
- both: coinfection of pharynx, rectum, eye may occur
- disseminated infection- lack of urogenital symptoms, arthritis/dermatitis, septic arthritis, rarely meningitis, endocarditis
- neonate- bilateral conjunctivitis, if untreated, permanent blindness
5
Q
Diagnosis of Gonorrhea- Lab
A
- Male- first, test urine and exudate for PMNs and intracellular diplococci, if needed obtain urethral swab for gram stain, culture on Thayer Martin agar, Required if case has legal implications
- Female- obtain endocervical smear, culture on Thayer-Martin
- Disseminated gonococcal infection- gram stain, culture samples from all affected areas, blood, joint fluid may be cultured on nonselective chocolate agar
6
Q
Treatment of Gonorrhea
A
- begin antibiotics before labs come back
- ceftriaxone, alternate cefixime, cephalosporin
- add axithromycin or doxycycline for coinfection with Chlamydia
- aspirate septic joints
- admit if pregnant, PID, DGI, endocarditis, meningitis, purulent joint infection
- if living in an area with known Ab resistance problems, test cure 1 week after treatment. Otherwise, follow up in 3 months
7
Q
Prevention of Gonorrhea
A
- Neonate- erythromycin ointment on eyes at birth
- STD: condoms, treat all sexual contacts
- report cases to local health authorities
- expedited partner treatment may be warranted
8
Q
Bacteriology of C. trachomatis
A
- unique life cycle: dense, rugged elementary bodies attach to cell, endocytosed, survive, unpack into reticulate bodies
- then larger delicate, RBs replicate, metabolize, pack into EBs, escape host cell
- only EBs are infectious, only RBs divide
9
Q
Pathogenesis of Genital Chlamydia trachomatis
A
- symptoms determined by serovar
- serovars A, B, Bb, C: blinding trachoma: leading cause of preventable blindness, spread by secretions, fomites, endemic to Africa, southern Asia
- Serovars L1-L3: lymphogranuloma venereum- small ulcer proceeds to painfully swollen lymph nodes near genitals, sexually transmitted, endemic to south and central america
- Serovars D-K: genital “chlamydia”- the most common STD in the US, often asymptomatic, may spread sexually or infect newborns at birth
10
Q
Diagnosis of Chlamydia
A
- blinding tachoma- eyelashes turned inward, travel to endemic area
- LG: buboes, history of sex while traveling
- Genital Chlamydia- history of nonbarrier contraceptives, multiple sexual partners, age <19, socioeconomically disadvantaged
11
Q
Exam for Chlamydia
A
- female: easily induced endocervical bleeding, mucopurulent endocervical discharge, bleeding, dysuria, abdominal pain, progression to pelvic inflammatory disease
- male: urethral discharge, dysuria, scrotal pain, perineal fullness
- both: Risk of Reiter Syndrome= Reactive Arthritis
- infant: occular trachoma/ pneumonia
12
Q
Labs for Chlamydia
A
- infant ocular trachoma: stain eye swab with Giema or IF for chlamydial inclusions
- culture- C. trachomatis grows well in many common cell lines, culture required if case has legal implications
- molecular methods like fluorescent hybridization, ELISA, PCR- easier and cheaper than culture, more likely to give a false positive- you detect the chlamydial rRNA
- serology not useful because past infection is too common
13
Q
Treatment for Chlamydia
A
- antibiotics are indicated, must be able to penetrate infected cell membranes- doxycycline or azithromycin
- peds, pregnanty, allergix- erythromycin and amoxicillin, test the cure
- reinfection is very common
- treat all sexual partners
- condoms
- counsel about risk of Reactive Arthritis sequel
14
Q
Differences between N. gonorrhoeae and N. meningitidis
A
- not encapsulated
- hundreds of serotypes
- even more sensitive to dehydration, cold
- plasmid-borne antibiotic resistance more common (new and improved with cephalosporin resistance
15
Q
N. gonorrhoeae Virulence factors
A
- IgA protease clears IgA from mucosal surfaces to facilitate 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, enhance cell entry
- LOS: less immunogenic than LPS, but does not induce local inflammatory response (the Drip, the Clap)
