What is the recommended approach to diagnose a gonorrheal (Neisseria gonorrhoeae) infection?

Diagnosis of Gonorrheal Infection

For genitourinary gonorrhea in adults, nucleic acid amplification tests (NAATs) on urine, vaginal swabs, or urethral swabs are the preferred diagnostic method, with culture reserved for extragenital sites (pharynx and rectum) or when antimicrobial susceptibility testing is needed. 1

Genitourinary Testing in Adults

Preferred Diagnostic Method

• NAATs are the gold standard for genitourinary gonorrhea, offering superior sensitivity (>95%) and specificity (>99%) compared to culture or Gram stain 1, 2
• FDA-cleared specimen types include: endocervical swabs, vaginal swabs (provider or self-collected), male urethral swabs, and urine from both sexes 1
• Vaginal swabs (including self-collected) are increasingly preferred over cervical swabs due to comparable accuracy with improved patient comfort 1

Culture as Alternative

• Culture remains acceptable when NAATs are unavailable, requiring endocervical swabs in females or urethral swabs in males 3
• All presumptive N. gonorrhoeae isolates must be confirmed by at least two different testing methods (e.g., biochemical, enzyme substrate, or serologic) to avoid false positives 4
• Isolates should be preserved for potential antimicrobial susceptibility testing, which is critical given rising antibiotic resistance 4

Gram Stain Utility

• In symptomatic men with urethral discharge, Gram stain showing polymorphonuclear leukocytes with intracellular Gram-negative diplococci is diagnostic (specificity >99%, sensitivity >95%) 1
• Gram stain is inadequate for women, asymptomatic men, and all extragenital sites and should not be used to exclude infection 4, 1

Extragenital Site Testing

Pharyngeal Gonorrhea

• Culture is the recommended diagnostic method for pharyngeal specimens because NAATs are not FDA-cleared for this site and may cross-react with commensal Neisseria species (N. meningitidis, N. sicca, N. lactamica) 1, 5
• NAATs may be used only if the laboratory has validated the assay and meets CLIA requirements, with expert consultation to interpret positive results 4

Rectal Gonorrhea

• Culture is generally recommended for rectal specimens, as NAATs are not FDA-cleared for this site 1
• Laboratory-validated NAATs can be used when available, particularly in men who have sex with men where rectal infections are common 1, 5

Special Populations

Prepubertal Children (Sexual Abuse Cases)

• Only standard culture methods should be used in children due to legal implications of false-positive results 4
• Specimen collection sites: pharynx and anus in both sexes, vagina in girls, urethra in boys (meatal specimen acceptable if discharge present) 4
• Cervical specimens are not recommended for prepubertal girls 4
• All presumptive isolates must be confirmed by at least two different testing methods and preserved 4
• NAATs may be considered for vaginal secretions or urine in girls only with expert consultation and confirmation capability, but culture remains preferred for urethral specimens in boys and all extragenital sites 4
• Gram stains are inadequate and should not be used in children 4

Timing of Testing in Abuse Cases

• Initial examination may yield false negatives if exposure was recent (insufficient organism concentration) 4
• Schedule follow-up examination approximately 2 weeks after last sexual exposure for repeat specimen collection 4

Comprehensive STI Screening Requirements

• All patients tested for gonorrhea must be simultaneously tested for chlamydia, syphilis, and HIV 1, 5
• Sexual history should determine all anatomical sites requiring testing (genital, rectal, pharyngeal) based on specific sexual practices 5, 3
• Men who have sex with men require pharyngeal and rectal testing based on sexual practices 5

Follow-Up Testing

• Retest all patients approximately 3 months after treatment due to high reinfection rates (20-30%), regardless of whether partners were treated 5, 6
• Test-of-cure is not routinely recommended for uncomplicated infections treated with recommended regimens 4
• Persistent symptoms after treatment warrant repeat culture with antimicrobial susceptibility testing 4

Common Diagnostic Pitfalls

• Do not rely on negative Gram stain to exclude infection in women or asymptomatic men 1
• Do not use non-FDA-cleared NAATs for extragenital sites without proper laboratory validation 1
• Do not use nonculture tests (including NAATs) in child sexual abuse cases without confirmation 4
• Avoid using only syndromic management in women, as vaginal discharge has multiple etiologies and leads to overtreatment 7
• Remember that 70% of gonorrhea infections may be asymptomatic or minimally symptomatic, particularly extragenital infections 2