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MS2 Unit 1 > Micro: Gonorrhea and Chlamydia > Flashcards

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)
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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)
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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
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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
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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
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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
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7
Q

How contagious is gonorrhea?

A
  • Extremely contagious: single-exposure contraction common

- Symptoms develop quickly, within 10 days of infection

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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)
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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)
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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
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11
Q

Fitz-Hugh-Curtis syndrome

A

bacteria (either gonorrea or chlamydia) jump from fallopian tube to liver capsule –> acute perihepatitis

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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)
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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)
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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
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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
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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

MS2 Unit 1 (11 decks)

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