Closthioamide Inhibits Growth of Multidrug-Resistant Gonorrhea

gonorrhea bacteria
gonorrhea bacteria
A promising new treatment has been identified in the fight against multidrug-resistant gonorrhea.

Closthioamide inhibits the growth of most clinical gonococcal strains in vitro, according to a new study published in Antimicrobial Agents and Chemotherapy.

Researchers tested the inhibitory effects of closthioamide in 149 clinical strains of Neisseria gonorrhoeae as well as 4 commensal Neisseria strains. The minimum inhibitory concentration (MIC) was calculated by agar dilution using closthioamide concentrations of 0.002 mg/L to 1 mg/L.

In 146 of the 149 clinical N gonorrhoeae strains, the closthioamide MIC was ≤ 0.125 mg/L. Among the various isolates, closthioamide MICs were 0.008 mg/L (n=1, 1%)), 0.015 mg/L (n=6, 4%), 0.031 mg/L (n=14, 9%), 0.063 mg/L (n=53, 36%), 0.125 mg/L (n=72, 48%), and 0.25 mg/L (n=3, 2%).

The closthioamide MICs in N lactamica and N perflava were 0.063 mg/L and 0.5 mg/L, respectively. Both N flavescens strains examined had MICs >1 mg/L.

No correlation was found between susceptibility to closthioamide and susceptibility to other antibiotics, suggesting a unique mechanism of action.

Dr John Heap, corresponding author on the study, said, “We thought it noteworthy that we did not observe cross-resistance with other antimicrobials including antibiotics currently used as treatments for gonorrhoea.” He pointed out, however, that “polythioamides are not yet close to clinical application.”

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Miari VF, Solanki P, Hleba Y, Stabler RA, Heap JT. In vitro susceptibility to closthioamide among clinical and reference strains of Neisseria gonorrhoeae [published online August 7, 2017]. Antimicrob Agents Chemother. doi:10.1128/AAC.00929-17