Micro: Gonorrhea and Chlamydia Flashcards
1
Q
How is N. gonorrhoeae like N. meningitides?
A
- Diplococci
- Human-restricted
- Oxidase-positive
- Cleared from bloodstream by immune complement: complement deficiencies are predisposing for complications
- Growth in vitro inhibited by trace metals and fatty acids: “chocolate” agar not blood agar
- Gram-Negative LOS (lipooligosaccharide)
2
Q
How is N. gonorrhoeae unlike N. meningitides?
A
- Not encapsulated
- Hundreds of serotypes
- Even more sensitive to dehydration, cold
- Plasmid-borne antibiotic resistance more common (newly cephalosporin resistant)
3
Q
N. gonorrhoeae Pathogenesis
A
- Transmitted sexually or at birth
- Neonate: purulent conjunctivitis
- Male: usually symptomatic: anterior 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
4
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&entry - Porin A and B channels in outer membrane confer serum resistance, enhance cell entry
- LOS: less immunogenic than LPS, but does induce local inflammatory response
5
Q
Pelvic Inflammatory Disease
A
- 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 – can be some “twitching motility” by pili
6
Q
Disseminated Gonococcal Infection
A
- 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
7
Q
How contagious is gonorrhea?
A
- Extremely contagious: single-exposure contraction common
- Symptoms develop quickly, within 10 days of infection
8
Q
Male symptoms of gonorrhea
A
- urethritis, dysuria, purulent discharge, sometimes unilateral epididymitis
- Co-infection of pharynx, rectum, eye (All appear as irritated/destroyed tissue with discharge)
9
Q
Female symptoms of gonorrhea
A
- May be asymptomatic
- purulent vaginal discharge, cervicitis, pelvic inflammatory disease–>sterility, ectopic pregnancy
- Co-infection of pharynx, rectum, eye (All appear as irritated/destroyed tissue with discharge)
10
Q
Pelvic Inflammatory Disease symptoms
A
- Lower abdominal pain
- Vaginal discharge
- Dysuria
- Tenderness
- Intermenstrual bleeding
- Fitz-Hugh-Curtis syndrome: bacteria (either gonorrea or chlamydia) jump from fallopian tube to liver capsule –> acute perihepatitis
- Sonogram may show thick Fallopian tubes or abscess
11
Q
Fitz-Hugh-Curtis syndrome
A
bacteria (either gonorrea or chlamydia) jump from fallopian tube to liver capsule –> acute perihepatitis
12
Q
Disseminated gonorrhea infection (DGI)
A
- 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)
13
Q
2 rare complications of gonorrhea
A
- 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)
14
Q
Neonatal gonorrhea infection
A
- 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
15
Q
Male gonorrhea testing
A
Try first: urine & exudate testing
- Obtain & centrifuge first-morning void, swab exudate
- Gram stain: PMNs indicate urethritis, Gram(-) intracellular diplococci indicate gonorrhea
- Nucleic acid amplification tests (NAAT) give the best sensitivity&specificity for +/- (Organism is delicate, so sample handling can be a real issue for culture.)
- BUT culture is currently required for antimicrobial susceptibility testing.
If repeat NAAT or culture is required: obtain urethral swab
- Gram stain (same)
- Culture on Thayer-Martin: chocolate agar with drugs to inhibit normal flora
- Colonies tested for Gram(-), Oxidase(+) diplococci
16
Q
Female gonorrhea testing
A
- Obtain endocervical smear (urethral sample if hysterectomy); wipe off exudate first
- NAAT
- If needed, culture on Thayer-Martin
17
Q
DGI testing
A
- Swab, gram stain, and culture all available mucosal surfaces & fluid draws
- Samples from normally-sterile sites (blood, joint fluid) may be cultured on nonselective chocolate agar
- Immunofluorescence may give better results than gram stain on pustule samples
18
Q
Differentiating N. meningitides and N. gonorrhoeae on exam
A
Only meningococci ferment maltose. Alternatively, immunofluorescence
19
Q
Gonorrhea treatment
A
- Begin promptly, in advance of labwork if necessary
- Check local situation for antimicrobial resistance testing
- Ceftriaxone, alt cefixime
- If allergic to penicillin, cephalosporin (watch for resistance!)
- Add azithromycin or doxycycline because chlamydia often co-infects
- Aspirate septic joints
- If living in an area with known Ab resistance problems, test cure 1wk after treatment. Otherwise, follow-up in 3 months.
- Admit if: Pregnant, PID, DGI, endocarditis, meningitis, purulent joint infection
20
Q
Gonorrhea prevention
A
- Neonatal conjunctivitis: prophylactic application of erythromycin ointment or silver nitrate to eyes shortly after birth
- STD: condoms, prompt treatment of patient and all sexual contacts
- Report incidence to local health authority, enlist them if patient resists informing sexual partners.
- “Expedited partner treatment” (EPT) (providing scripts without exam) may be warranted in some cases.
21
Q
What are the 2 cell types of chlamydia replication?
A
Elementary bodies and reticulate bodies
22
Q
Chlamydia elementary bodies
A
- Small (0.3 - 0.4 μm)
- Infectious
- Rigid outer membrane
- Rugged
- Bind to receptors on epithelium of lung or mucus membrane and initiate infection
23
Q
Chlamydia reticulate bodies
A
- Non-infectious intracellular form
- Metabolically active
- Replicating
- Synthesizes its own DNA, RNA, and proteins, but requires ATP from host
- Fragile Gram(-) membrane
- Inclusions accumulate 100-500 progeny before release
24
Q
Chlamydia immune response
A
- 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)
25
Q
Chlamydia serovars
A
18 serovars:
A, B, Ba, and C: blinding trachoma
L1-L3: lymphogranuloma venereum
D-K: genital tract infections
26
Q
Blinding trachoma
A
- Infectious eye disease, leading cause of preventable blindness
- 84 million people suffer, 8 million visually impaired
- Spread by secretions - direct and fomites
- Untreated eyelids turn inward, causing the eyelashes to scratch the cornea.
- WHO aims to eradicate by 2020
27
Q
Lymphogranuloma Venereum
A
- Endemic in South and Central America, emerging in US (obtain history of sex while traveling)
- A small, painless ulcer proceeds to swollen, painful lymph nodes (buboes)
- Symptoms are 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.
28
Q
Genital chlamydia
A
- Often asymptomatic – particularly in male “reservoirs”
- Most commonly local mucosal inflammation & 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
29
Q
Genital chlamydia risk factors
A
- Nonbarrier contraceptive use
- Multiple sexual partners
- Single marital status
- Age
30
Q
Reiter Syndrome aka Reactive Arthritis
A
- 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 leucocyte antigen-B27 (HLA-B27)–positive.
- Treated with NSAIDs, may take 2yrs to resolve
31
Q
Female chlamydia on exam
A
- May be asymptomatic
- Easily induced endocervical bleeding
- Mucopurulent endocervical discharge
- Intermenstrual bleeding
- Dysuria
- Abdominal pain
32
Q
Male chlamydia on exam
A
- Urethral discharge
- Urinary frequency and/or urgency
- Dysuria
- Scrotal pain/tenderness
- Perineal fullness
33
Q
Chlamydia diagnosis
A
- *Test for co-incident Chlamydia in all STD patients **
- Usual options: NAAT or cell culture
- NAAT generally gives the best reliable results (faster, more sensitive).
- BUT, C trachomatis grows easily in a variety of cell lines; culture still works well for hospitals that don’t have NAAT equipment.
- Also: Cytologic diagnosis for infant ocular trachoma (Cell sample is stained by Giemsa or IF)
- Serology not useful for N. gonorrhoeae or C. trachomatis (past infection too common)
34
Q
Chlamydia treatment
A
- Chlamydia is INTRACELLULAR, so antibiotic must be also
- First choice: doxycycline or azithromycin
- Doxycycline is contraindicated in pregnant or
