P09.15 Time to clearance for molecular test-of-cure among men treated for urethral, pharyngeal, or rectal gonorrhoea in san francisco, 2013–2014

Gentamicin as an alternative to ceftriaxone in the treatment of gonorrhoea: the G-TOG non-inferiority RCT

BACKGROUND

Gonorrhoea is a common sexually transmitted infection that can cause pain and discomfort, affect fertility in women and lead to epididymo-orchitis in men. Current treatment is with ceftriaxone, but there is increasing evidence of antimicrobial resistance reducing its effectiveness. Gentamicin is a potential alternative treatment requiring further evaluation.

OBJECTIVES

To assess the clinical effectiveness and cost-effectiveness of gentamicin as an alternative treatment to ceftriaxone in the treatment of gonorrhoea.

DESIGN

A multicentre, parallel-group, blinded, non-inferiority randomised controlled trial.

SETTING

Fourteen sexual health clinics in England.

PARTICIPANTS

Adults aged 16-70 years with a diagnosis of uncomplicated, untreated genital, pharyngeal or rectal gonorrhoea based on a positive Gram-stained smear on microscopy or a positive nucleic acid amplification test (NAAT).

RANDOMISATION AND BLINDING

Participants were randomised using a secure web-based system, stratified by clinic. Participants, investigators and research staff assessing participants were blinded to treatment allocation.

INTERVENTIONS

Allocation was to either 240 mg of gentamicin (intervention) or 500 mg of ceftriaxone (standard treatment), both administered as a single intramuscular injection. All participants also received 1 g of oral azithromycin.

MAIN OUTCOME MEASURE

The primary outcome measure was clearance of Neisseria gonorrhoeae at all infected sites, confirmed by a negative Aptima Combo 2® (Hologic Inc., Marlborough, MA, USA) NAAT, at 2 weeks post treatment.

RESULTS

We randomised 720 participants, of whom 81% were men. There were 358 participants in the gentamicin group and 362 in the ceftriaxone group; 292 (82%) and 306 (85%) participants, respectively, were included in the primary analysis. Non-inferiority of gentamicin to ceftriaxone could not be demonstrated [adjusted risk difference for microbiological clearance -6.4%, 95% confidence interval (CI) -10.4% to -2.4%]. Clearance of genital infection was similar in the two groups, at 94% in the gentamicin group and 98% in the ceftriaxone group, but clearance of pharyngeal infection and rectal infection was lower in the gentamicin group (80% vs. 96% and 90% vs. 98%, respectively). Reported pain at the injection site was higher for gentamicin than for ceftriaxone. The side-effect profiles were comparable between the groups. Only one serious adverse event was reported and this was deemed not to be related to the trial medication. The economic analysis found that treatment with gentamicin is not cost neutral compared with standard care, with average patient treatment costs higher for those allocated to gentamicin (£13.90, 95% CI £2.47 to £37.34) than to ceftriaxone (£6.72, 95% CI £1.36 to £17.84).

LIMITATIONS

Loss to follow-up was 17% but was similar in both treatment arms. Twelve per cent of participants had a negative NAAT for gonorrhoea at their baseline visit but this was balanced between treatment groups and unlikely to have biased the trial results.

CONCLUSIONS

The trial was unable to demonstrate non-inferiority of gentamicin compared with ceftriaxone in the clearance of gonorrhoea at all infected sites. Clearance at pharyngeal and rectal sites was lower for participants allocated to gentamicin than for those allocated to ceftriaxone, but was similar for genital sites in both groups. Gentamicin was associated with more severe injection site pain. However, both gentamicin and ceftriaxone appeared to be well tolerated.

FUTURE WORK

Exploration of the genetic determinants of antibiotic resistance in N. gonorrhoeae will help to identify accurate markers of decreased susceptibility. Greater understanding of the immune response to infection can assist gonococcal vaccine development.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN51783227.

FUNDING

This project was funded by the National Institute for Health Research Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 23, No. 20. See the NIHR Journals Library website for further project information.

Spontaneous clearance of genital and extragenital Neisseria gonorrhoeae: data from GToG

OBJECTIVES

Neisseria gonorrhoeae (NG) infection can resolve without antibiotic treatment, however the literature describing the frequency of clearance at individual sites, how rapidly it occurs and potential predictive factors is limited. In this analysis of a subpopulation identified from a large multicentre UK cohort, we describe the overall rate of spontaneous clearance of infection and explore factors associated with this.

METHODS

Data from the Gentamicin compared with Ceftriaxone for the Treatment of Gonorrhoea randomised controlled trial consisting of 720 patients with NG were analysed. A subgroup of individuals had both a pretrial test sample and a trial enrolment sample taken. Those who had cleared NG between initial presentation and subsequent entry into the trial without antibiotic treatment were deemed to have spontaneously cleared. Sociodemographic characteristics, sexual history and sites of infection for those who spontaneously cleared infection were compared with that of those who did not. We also estimated the time interval to clearance.

RESULTS

Overall, the proportion who had spontaneous clearance was 20.5% (83/405). Clearance of infection occurred over a median of 10 days (IQR 7-15 days). The cohort who spontaneously cleared were similar to those who did not in terms of age, gender, sexual orientation, HIV status and previous NG infection. Chlamydia coinfection was more frequent in the 'no spontaneous clearance group' (11.1% (9/83) cf 22.0% (69/322)) (p=0.029). Dysuria was reported more often in the 'no spontaneous clearance group' (4.8% (4/83) cf 13.0% (42/322)) (p=0.035).

CONCLUSION

We present data from a large cohort of NG-infected individuals, of whom a significant proportion had spontaneous clearance of infection. This is consistent with previous smaller studies. If this is indicative of cure, point-of-care testing prior to treatment has the potential to reduce unnecessary exposure to antimicrobials. Further work to assess the importance of bacterial load, genotype and host immune response on spontaneous clearance of infection is required.

TRIAL REGISTRATION NUMBER

ISRCTN51783227.