Non-culture Neisseria gonorrhoeae molecular penicillinase production surveillance demonstrates the long-term success of empirical dual therapy and informs gonorrhoea management guidelines in a highly endemic setting

Abstract

Unlike most of the world, penicillin resistance in Neisseria gonorrhoeae from remote regions of Western Australia (WA) with high gonorrhoea notification rates has not increased despite many years of empirical oral therapy. With the advent of non-culture molecular diagnosis of gonorrhoea and the consequent decline in culture-based susceptibility, it is imperative to ensure the ongoing reliability of combination oral azithromycin, amoxicillin and probenecid for uncomplicated gonorrhoea in this setting. PCR-based non-culture N. gonorrhoeae antimicrobial resistance surveillance for penicillinase production was therefore employed. Genital and non-genital specimens that were PCR-positive for N. gonorrhoeae were assessed for penicillinase production by detection of the N. gonorrhoeae TEM-1 plasmid using specific real-time PCR. In remote regions of WA where gonorrhoea is highly endemic, <5% of N. gonorrhoeae isolates were penicillinase-producing. This contrasts with rates of up to 20% observed in the more densely populated metropolitan and rural regions. In the era of molecular diagnosis of gonorrhoea, non-culture-based antimicrobial resistance surveillance proved useful when developing evidence-based guidelines for the clinical management of locally acquired gonorrhoea in highly endemic regions in WA. The continued efficacy of combination oral amoxicillin, probenecid and azithromycin therapy despite many years of use in a setting highly endemic for gonorrhoea may explain the low rate of penicillin resistance in these remote regions and supports the concept of adding azithromycin to β-lactam antibiotics to help delay the emergence of multiresistant N. gonorrhoeae.