Characterization of new bacteriophage active against Staphylococcus aureus

Author: ANNA IARAJULI
Keywords: Staphylococcus aureus, bacteriophages, phage therapy
Annotation:

Antibiotic-resistant bacteria are becoming significantly prevalent globally and their prevalence continues to rise, primarily attributable to overuse and inappropriate use of antibiotics. Infections stemming from resistant bacterial strains constitute a profound menace to worldwide public health, culminating in an annual toll of millions of fatalities. One of the most widespread pathogens notoriousely resistant to antibiotics is Staphylococcus aureus. S. aureus is a gram-positive spherical bacterium that causes skin and mucous membrane infections, respiratory tract infections, endocarditis, osteomyelitis, toxic shock syndrome, food poisoning, sepsis, and more. S. aureus belongs to the group of bacteria called "ESKAPE" (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacteriaceae). These bacteria are of especial concern since new antimicrobials against them are urgently needed. Therefore, finding new effective treatments against S. aureus-related infectious diseases remains rather important. Nowadays, bacteriophages are actively considered as an alternative means of treatment. Bacteriophages are the most diverse group of viruses widely distributed in the living world. Phages are viruses of bacteria and have many advantages over antibiotics. First of all, they are characterized by specificity towards their target bacteria. It is easy to isolate them from different environments and work with them is also not complicated. Importantly, there are no side effects during phage treatment. Our study aims to characterize a new phage active against S. aureus bacteria and to compare it with a well-characterized therapeutic bacteriophage in the commercial staphylococcal bacteriophage preparation. The phage active against S. aureus used in the study (vB_Sa S13) was isolated from Black Sea water. We estimated the genome size of the new phage, performed DNA restriction analysis, and determined the morphology and its range of lytic activity. Lastly, we compared it with the Sb-1 phage, which is well-characterized and actively used for treatment. Our present work has revealed that vB_Sa S13 phage belongs to the Siphoviridae morphological group, it is characterized by a narrow lytics spectrum (infects only seven of the 71 tested strains), and has a fairly small genome. vB_Sa S13 phage differs from the Sb-1 phage in terms of morphological and biological characteristics. Based on the obtained results, we can conclude that vB_Sa S13 phage can be used in personalized therapy (as an autophage) because it lyses bacterial cells against which the broad-spectrum Sb-1 phage is not active.