Case-Based Study Questions on Neisseria gonorrhoeae: Diagnostic Tests, Treatment, and Epidemiology

Clinical Features

-swollen eye with oozing pus
-weepy eye with thick purulent discharge
-conjunctival edema → conjunctival involvement can progress to corneal involvement (marginal infiltrate, ulceration, perforation)
-conjunctival hyperemia
-red swollen eyelid
-massive exudation
-severe chemosis
-eyelid edema
-pseudomembrane
-tenderness of the globe
-tender preauricular lymphadenopathy

Epidemiology

-associated with septic arthritis, salpingitis (form of pelvic inflammatory disease), dermatitis arthritis syndrome, neonatal conjunctivitis, and hyperacute conjunctivitis
-LOS is readily shed → induces endotoxemia
-transmission: primarily sexual contact
-incidence highest in 15-24 y/o and those who've had multiple sexual encounters

Microbiology

-gram (-), non-motile, bean-shaped diplococci
-oxidase (+) and catalase (+)
-ferments glucose only (not maltose)
-tropism for mucosal epithelium
-no capsule

Virulence Factors

-Pili & OMPII: promote adherence to and invasion of mucosal cells (OMP: outer membrane protein)
-Endotoxin release: causes fever, vascular permeability, inflammation, and tissue destruction
-IgA protease: cleaves secretory IgA → reduces host defense
-Antigenic variation

Diagnostic Tests

-gram stain: gram (-) intracellular diplococci → pink/red staining with adjacent sides flattened
-Thayer-Martin media (selective chocolate agar): contains vancomycin (kills gram (+)), colistin (kills gram (-) except Neisseria spp. due to lack of LPS), and nystatin (kills fungi)
-Genital and throat swabs in patients with risk factors: sexual partners of patients with gonorrhea and motors of neonates with gonococcal conjunctivitis

Treatment

-Cefixime, Ceftriaxone, and Azithromycin

-DOC: ceftriaxone with either azithromycin or doxycyline

-dissemination/bacteremia → prolonged penicillin or ceftriaxone therapy

-ophthalmia neonatorum → ceftriaxone

-highly resistant to cephalosporins, penicillins, and fluoroquinolones