Antimicrobial activity of enacyloxin IIa and gladiolin against the urogenital pathogens Neisseria gonorrhoeae and Ureaplasma spp

Aims: To determine the antimicrobial activity of enacyloxin IIa and gladiolin against Neisseria gonorrhoeae and Ureaplasma spp. Methods and Results: The Burkholderia polyketide antibiotics enacyloxin IIa and gladiolin were tested against 14 N. gonorrhoeae and 10 Ureaplasma spp. isolates including multidrug-resistant N. gonorrhoeae isolates WHO V, WHO X and WHO Z as well as macrolide, tetracycline and ciprofloxacin-resistant ureaplasmas. Susceptibility testing of N. gonorrhoeae was carried out by agar dilution, whereas broth micro-dilution and growth kinetic assays were used for Ureaplasma spp. The MIC range for enacyloxin IIa and gladiolin against N. gonorrhoeae was 0·015–0·06 mg l⁻¹ and 1–2 mg l⁻¹ respectively. The presence of resistance to front line antibiotics had no effect on MIC values. The MIC range for enacyloxin IIa against Ureaplasma spp. was 4–32 mg l⁻¹ with a clear dose-dependent effect when observed using a growth kinetic assay. Gladiolin had no antimicrobial activity on Ureaplasma spp. at 32 mg l⁻¹ and limited impact on growth kinetics. Conclusions: Enacyloxin IIa and gladiolin antibiotics have antimicrobial activity against a range of antibiotic susceptible and resistant N. gonorrhoeae and Ureaplasma isolates. Significance and Impact of the Study: This study highlights the potential for a new class of antimicrobial against pathogens in which limited antibiotics are available. Development of these compounds warrants further investigation in the face of emerging extensively drug-resistant strains.