In vitro activity of the new fluoroketolide solithromycin (CEM-101) against a large collection of clinical Neisseria gonorrhoeae isolates and international reference strains, including those with high-level antimicrobial resistance: potential treatment option for gonorrhea?

Abstract

Gonorrhea may become untreatable, and new treatment options are essential. We investigated the in vitro activity of the first fluoroketolide, solithromycin. Clinical Neisseria gonorrhoeae isolates and reference strains (n = 246), including the two extensively drug-resistant strains H041 and F89 and additional isolates with clinical cephalosporin resistance and multidrug resistance, were examined. The activity of solithromycin was mainly superior to that of other antimicrobials (n = 10) currently or previously recommended for gonorrhea treatment. Solithromycin might be an effective treatment option for gonorrhea.

Fig 1

Chemical structure of solithromycin (also known as CEM-101). The molecule possesses an 11,12-carbamate-butyl-[1,2,3]-triazolyl-aminophenyl side chain (circled) and a fluorine atom (circled) substituting for a hydrogen atom in position 2 of the lactone (macrolide) ring. These alterations constitute the main differences compared to the structure of telithromycin (which causes several severe side effects [25]) and other macrolides-ketolides and appear to account for the more potent activity and great tolerability of solithromycin.

Fig 2

MIC (μg/ml) distribution of solithromycin, azithromycin, and telithromycin for 246 clinical N. gonorrhoeae isolates and international reference strains.