High in vitro activity of DIS-73285, a novel antimicrobial with a new mechanism of action, against MDR and XDR Neisseria gonorrhoeae.

BACKGROUND

The rising incidence of antimicrobial resistance in Neisseria gonorrhoeae may result in untreatable gonorrhoea in certain circumstances and development of novel antimicrobials is urgently needed.

OBJECTIVES

To evaluate the in vitro activity of a novel small-molecule antimicrobial with a new mechanism of action, DIS-73285, against a large geographically, temporally and genetically diverse collection of clinical N. gonorrhoeae isolates and reference strains, including various types of high-level resistant, MDR and XDR gonococcal isolates (n = 262).

METHODS

MICs (mg/L) of DIS-73285 were determined by agar dilution and by Etest for ceftriaxone, cefixime, azithromycin, ciprofloxacin, ampicillin, spectinomycin and tetracycline.

RESULTS

DIS-73285 was substantially more potent than any of the currently or previously used therapeutic antimicrobials, with MICs ranging from ≤0.001 to 0.004 mg/L, and the MIC50, MIC90 and modal MIC all ≤0.001 mg/L (lowest MIC tested). No correlation with the MICs of DIS-73285 and the MICs of any of the currently or previously used antimicrobials was observed.

CONCLUSIONS

The novel chemotype, small-molecule antimicrobial DIS-73285, demonstrated high in vitro potency against all tested N. gonorrhoeae isolates. Further in vitro and in vivo studies, evaluating efficacy, resistance emergence, pharmacokinetic/pharmacodynamic parameters, toxicity and safety, should be conducted to evaluate DIS-73285 as a therapy specifically for urogenital and extra-genital gonorrhoea.