Culture obtained from urethral swab of asymptomatic men who screen positive for by urine nucleic acid amplification testing.

BACKGROUND

In a previous study of men attending Melbourne Sexual Health Centre who had detected by urine Aptima Combo 2 (AC2) testing, 11% were asymptomatic. This study aimed to determine whether can be cultured from asymptomatic men screening positive for by nucleic acid amplification testing (NAAT) of urine.

METHODS

Between 1 July 2017 and 31 March 2019, all men attending Melbourne Sexual Health Centre were tested for by AC2 testing of urine whether urethral symptoms were reported or not. NAAT-positive men were recalled and a urethral swab performed for gonococcal culture using modified Thayer-Martin media with determination of minimum inhibitory concentrations (MICs) by agar dilution.

RESULTS

There were 1001 cases (860 individuals) positive for by urine AC2: 892 (89%) reported urethral symptoms; 109 (11%) did not. Twenty-five asymptomatic cases were excluded because of antibiotic use at or following screening. Of the remaining 84 asymptomatic men, 41 (49%) had a urethral swab performed a median of 5 days after screening. Twenty-one men had urethral discharge at the return visit, 11 of whom reported the discharge at the return visit. Of the 41 men who were swabbed, 31 (76%; 95% CI 60% to 88%) were culture positive for . Among the 21 men who subsequently developed discharge, 19 (90%; 95% CI 70% to 99%) were culture positive. Among the 20 men who remained asymptomatic, 12 (60%; 95% CI 36% to 81%) were culture positive. MIC profiles were obtained from all isolates.

CONCLUSIONS

Gonorrhoea was isolated in most but not all asymptomatic men screening positive for by urine NAAT. Clinicians should consider performing urethral culture in such men to ensure optimal surveillance for antimicrobial resistance. Isolation of by culture in men without discharge indicates these are true infections with viable organisms.