Urethritis

Urethritis is inflammation of the urethral mucosa, predominantly caused by sexually transmitted pathogens. It is classified as gonococcal urethritis (GU - caused by Neisseria gonorrhoeae) or non-gonococcal urethritis (NGU - most commonly Chlamydia trachomatis, Mycoplasma genitalium, Ureaplasma urealyticum, and Trichomonas vaginalis). Neisseria gonorrhoeae is a gram-negative diplococcus that attaches to columnar urethral epithelial cells via type IV pili and opacity-associated (Opa) proteins. Following attachment, the organism is internalized through receptor-mediated endocytosis into non-acidic vacuoles, evading lysosomal destruction. Gonococcal lipooligosaccharide (LOS) activates toll-like receptor 4 (TLR4) on epithelial and immune cells, triggering NF-kB-mediated release of pro-inflammatory cytokines (IL-1β, IL-6, IL-8, TNF-α) and massive neutrophil recruitment - producing the characteristic purulent urethral discharge. Gonococcal antimicrobial resistance (AMR) is a critical public health concern. Penicillinase-producing N. gonorrhoeae (PPNG) emerged through acquisition of the bla-TEM plasmid. Chromosomal mutations in penA (encoding penicillin-binding protein 2), mtrR (efflux pump regulator), and porB (outer membrane porin) have progressively expanded resistance to penicillins, tetracyclines, fluoroquinolones, and now threaten extended-spectrum cephalosporins. The mosaic penA allele (incorporating sequences from commensal Neisseria species through horizontal gene transfer) reduces ceftriaxone binding affinity...