Species diversity among the genus <i>Streptomyces</i> members isolated from clinical material

Abstract

Recently, both in Russia and around the world, the number of cases detecting acid-fast microbial members from the order Actinomycetales while developing human bacterial infections has been increased. The most important pathogens in this bacterial order are the members from the families Mycobacteriaceae, Nocardiaceae, Gordoniaceae, Tsukamurellaceae, Promicromonosporaceae, Brevibacteriaceae, Streptomycetaceae. This work is devoted to analyzing prevalence and species diversity of representatives of the family Streptomycetaceae from the genus Streptomyces isolated from clinical material upon examining for tuberculosis. There were examined 865 cultures of clinical material samples while examining for tuberculosis, in which signs of growth of contaminating microflora were revealed, as well as 316 cultures of clinical material samples obtained during examination for tuberculosis, in which signs of growth of non-tuberculosis mycobacteria (NTM) were detected. The material was collected from January 2016 to January 2019. Samples with signs of growth of contaminating microflora allowed to identify 1,093 strains, samples with signs of growth of NTM 352 strains. Among them, the number of representatives of the genus Streptomyces comprised 39 strains. All Streptomyces strains were isolated from sputum. Variety of isolated Streptomyces: S. phaeochromogenes (13 strains), S. albus (1 train), S. avidinii (1 strain), S. badius (2 strains), S. chartreusis (2 strains), S. griseus (1 strain), S. hirsutus (2 strains), S. lavendulae (3 strains), S. violaceoruber (10 strains). Species identification was not possible for 4 strains. Analyzing the data obtained, it is possible to draw a conclusion about the moderate distribution of representatives of the genus Streptomyces in pattern of contaminating microflora while examining for tuberculosis. In pattern structure of isolated microorganisms, Streptomyces accounted for 3.3%. Among the microflora isolated from culture with signs of NTM growth, Streptomyces was presented by single strains. However, it should be noted that Streptomyces was the dominant group among acid-resistant actinomycetes in pattern of contaminating microflora and accounted for 38.3%. Taking into account the fact that a significant proportion of them were isolated as microbial associations, it can be concluded that Streptomyces turned out to be classical contaminants in this case. Nevertheless, we believe that the isolation of Streptomyces in association with clinically significant NTMs can be considered as an unfavorable factor due to the fact that antibiotic resistance genes are widespread among Streptomyces and may be transmitted to other types of microorganisms from the group of acid-resistant actinomycetes, including mycobacteria. Thus, the clinical material examining for tuberculosis is an interesting research object from which various representatives of acid-fast actinomycetes, including Streptomyces, can be isolated.