Studies on the Antibacterial activity of Leucomycin Against Antibiotic-Resistant Staphylococci

Abstract

It is a general trend that in most hospitals where antibiotics are used extensively, infections caused by antibiotic-resistant bacteria, especially staphylococci, including those of hospital-acquired, have been encountered with increasing frequency. Eisenberg et al¹⁾. stated that for several years following their introduction into clinical usage, erythromycin, chloramphenicol, and the tetracyclines were all effective in the treatment of penicillinresistant staphylococcal infections encountered in their hospitals, including those that were considered to be hospital-acquired, but by the midsummer of 1958, the effectiveness of erythromycin and the tetracyclines had declined to the point that only about 50% and 30–25% of the staphylococci, respectively, isolated from lesions were susceptible to these agents, and only chloramphenicol continued to show a relatively high degree of effectiveness, 80–85%.

In a previous study, the authors reported on the in vitro antibacterial activity of leucomycin-free base and the A₁ fraction (one of the biologically active components of leucomycin), pointing out that these drugs possess a strong antibacterial activity on antibiotic-resistant staphylococci. In view of a serious problem on antibiotic-sesistant staphylococcal infections and also of the effectiveness of leucomycin against erythromycinresistant staphylococci, as shown by Eisenberg et al. in clinical and laboratory examinations and also by the present authors in in vitro studies, an attempt was made to extend the studies on drug resistance or susceptibility of staphylococci to erythromycin and leucomycin in respects to (1) comparison of the in vitro acquired resistance of sensitive staphylococcal strains against the two antibiotics and cross resistance among them, and (2) comparison of the degree of growth of the sensitive and resistant strains, including those isolated from patients and those influenced by the addition of antibiotics to their growth environment. Through these experiments the authors expected to clarify the existence of any possible difference in antibacterial activity between the two antibiotics, though some informations available on these antibiotics showed that they have close similarities in physical, chemical and biological properties.