Gonorrhea Chlamydia Flashcards
N. gonorrhoeae Bacteriology
diplococci
human-restricted
oxidase-positive
cleared from bloodstream by immune complement: complement deficiencies are predisposing for complications
gram-negative LOS, lipooligosaccharide
no capsule
hundreds of serotypes
sensitive to dehydration, cold
plasmid-borne antibiotic resistance
N. gonorrhoeae pathogenesis
transmitted sexually or at birth
neonate: purulent conjunctivitis
Male: usually symptomatic antierior urethritis
female: often asymptomatic, cervicitis
Genital tract infections most common, anorectal and pharyngeal also occur
infection in children is a reportable marker for sexual abuse
approx 700K new infections/yr
most common in african americans, rural southeast, inner cities, young unmarried, low education (socioeconomic factors)
infection rates crashed in 1970s but have been creeping upward
N. gonorrhoeae virulence factors
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 & entry
Porin A and B channels in outwer membrane confer serum resistance, enhance cell entry
LOS: less immunogenic than LPS, but does induce local inflammatory response (The drip, the clap)
N. gonorrhoeae pathogenesis clinical
most infections are vaginal or urethral; antibodies, complement, neutrophils restrict to local site
PID follows from mixing bacteria with refluxed menstrual blood or attachment to sperm - can be come “twitching motility” by pili
dissemination (bacteremia) can occur
Certain strains more likely to disseminate
Virulence factor is “serum resistance”, including protein Porin A in cell wall (anti-complement)
More common in women
Asymptomatic infection, menses, pregnancy, and complement C6-C9 deficiency also predispose
N. gonorrhoeae diagnosis: exam
Extremely contagious: single-exposure contraction common
Symptoms develop quickly, within 10 days of infection
men: Urethritis, dysuria, purulent discharge, sometimes unilateral epididymitis
women: purulent vaginal discharge, cervicitis, pelvic inflammatory disease -> sterility, ectopic pregnancy
Both: co-infection of pharynx, rectum, eye All appear as irritated/destroyed tissue with discharge
Pelvic inflammatory disease: Lower abdominal pain Vaginal discharge Dysuria Tenderness Intermenstrual bleeding Fits-High-Curtis syndrome: bacteria (either gonorrea or chlamydia) jump from fallopian tube or liver capsule -> acute perihepatitis Sonogram may show thick fallopian tubes or abscess
Disseminated infection (DGI):
often lack urogenital symptoms
Arthritis/dermatitis syndrome with joint pain and skin pustules
Asymmetric tenosynovitis with pain in wrists and ankles
Moderate fever
Progression to septic asymmetric arthritis (knee common)
N. gonorrhoeae
Rare clinical conditions
Gonococcal meningitis: admit, spinal tap
Endocarditis: echocardiogram, cardio consult. More common in men. Aortic valve most common site. Subacute onset of fever, chills, sweats, malaise. Chest pain, cough
N. Gonorrhoeae in Neonates
Bilateral conjunctivitis
Generally infected at birth, can happen postpartum or in utero
Eye pain, redness, discharge
Infection may also be pharyngeal, respiratory, rectal, or disseminated
Untreated, permanent blindness follows quickly
N. gonorrhoeae diagnosis: lab males
try first: urine & exudate testing - Gram stain - PMNs indicate urethritis, gram (-) intracellular diplococci indicate gonorrhea
Nucleic acid amplification tests are available
IF NEGATIVE: Obtain urethral swab
Gram stain (same)
Culture on Thayer-Martin: chocolate agar with drugs to inhibit normal flora
Colonies tested for gram (-), oxidase (+) diplococci
Most sensitive and specific
N. gonorrhoeae diagnosis: lab females
obtain endocervical smear (urethral sample if hysterectomy); wipe off exudate first
Culture on thayer-martin
N. gonorrhoeae diagnosis: disemminate gonococcal infection
swab, gram stain, and culture all available mucosal surfaces & fluid draws
Samples from normally-sterile sites may be cultured on nonselective chocolate agar
Immunofluorescence may give better results than gram stain on pustule samples
N. gonorrhoeae treatment
ceftriaxone, alt cefixime
if allergic to penicillin, cephalosporin (watch for resistance!)
Add azithromycin or doxycycline because chlamydia often co-infects
Aspirate septic joints
area with known Ab resistance problems - test 1wk after treatment. Follow-up in 3 months
Admit if: pregnant, PID, DGI, endocarditis, meningitis, purulent joint infection
N. gonorrhoeae prevention
neonatal conjunctivitis: prophylactic application of erythromysin ointment or silver nitrate to eyes shortly after birth
Report incidence to local health authority
“expedited partner treatment’ (EPT) providing scripts without exam may be warranted in some cases
Chlamydia replication
Involved elementary bodies and reticulate bodies
Elementary bodies
small infectious rigid outer membrane rugged bind to receptors on epithelium of lung or mucus membrane and initiate infection
Reticulate bodies
non-infectious intracellular form
metabolically active
replicating
synthesizes its own DNA, RNA< and proteins, but requires ATP from host
Fragile gram (-) membrane
Inclsions accumulate 100-500 progeny before release
Immune response to chlamydia
Inflammatory cascade causes some of the symptoms (swelling, discharge) but usually fails to either clear the infection or prevent reinfection
No useful immune memory (reinfection common)
Urogenital chlamydia - organism
C. trachomatis
18 serovars:
A,B,Ba and C: blinding trachoma
L1-L3: lymphogranuloma venereum
D-K: genital tract infections
blinding trachoma = infectious eye disease, leading cause of preventable blindness
84 million ppl suffer
spread by secretions = direct and fomites
untreated eyelid turns inward causing eyelashes to scratch the cornea
Lymphogranuloma Venereum
Endemic in south and central america, rare in US (obtain history of sex while traveling)
small painless ulcer proceeds to swollen, painful lymph nodes (buboes)
Symptoms caused by bacterial replication in the mononuclear phagocytes of the local lymph nodes
labwork and treatment are the same as for other genital chlamydia
aspiration of buboes and fistulas may speed healing
Genital chlamydia
4 million infections per year
prevalance rates >10% in sexually active adolescent females
often asymptomatic - particularly in male “reservoirs”
Most commonly local mucosal inflammation and discharge: urethritis or urethritis/vaginitis/cervicitis
Infection increases risk of acquiring HIV
Pregnant women infected with chlamydia can pass the infection to their infants during delivery
leading cause of PID and infertility in women, creates risk of chronic pain and ectopic pregnancy
Reiter Syndrome aka reactive arthritis
reactive arthritis secondary to an immune-mediated response; chlamydia is one of several infections known to trigger it
defined as conjunctivitis + urethritis + arthritis
80% of affected patients are human leukocyte antigen B27 - HLA-B27 positive
Treated with NSAIDs, may take 2 years to resolve
Genital chlamydia diagnosis : exam women and men
Women:
easily induced endocervical bleeding
Mucopurulent endocervical discharge
intermenstrual bleeding
dysuria
abdominal pain
Men:
Urethral discharge
Urinary frequency and/or urgency
Dysuria
Scrotal pain/tenderness
Perineal fullness
Urogenital Chlamydia Diagnosis: Lab
physical findings are often sufficient for diagnosis, but labwork available
Option 1: Cytologic diagnosis
for infant ocular trachoma
cell sample is stained by giemsa or IF
Option 2: isolation in cell culture
C trachomatis grows well in a variety of cell lines
option 3: detection of chlamydial ribosomal RNA by hybridization with a DNA probe and other nucleic acid amplification methods - simpler and less expensive than culture, but more likely to give a false positive
ELISA and PCR from urine or exudate are also options
Serology not useful for C. trachomatis (past infection too common)
Urogenital Chlamydia: treatment
Chlamydia is INTRACELLULAR, so antibiotic must be also
First choice: doxycycline or azithromycin
Doxycycline is contraindicated in pregnant or <9yr old patients.
Second-choice: erythromycin and amoxicillin. Test the cure.
Chlamydial infection can be hidden “behind” gonococcal; test for full STD panel
Reinfection is very common
Treat the patient’s partner(s) also
