In-vitro studies on SQ 26,776, a new monobactam antibiotic

Abstract

SQ 26,776 (SQ), a new β -lactam antibiotic, was without effect on the growth or viability of small or large numbers of penicillin-sensitive and -resistant and tetracycline-resistant strains of Staphylococcus aureus . In contrast, low concentrations of the antibiotic were inhibitory to several different Gram-negative organisms, including Pseudomonas aeruginosa , Serralia marcescens and Escherichia coli . Higher concentrations were lethal to Ps. aeruginosa , although persisters were also found. SQ was stable to some types of β -lactamases, but appeared to be slightly susceptible to a Type IV enzyme. The antibiotic induced predominantly long filamentous forms in E. coli and Ps. aeruginosa .