医療微生物学と診断

Isolation and Characterization of Bacteriophage against Methicillin Resistant Staphylococcus aureus

Abstract

Mariem N Mohammed-Ali and Nidham M. Jamalludeen

Methicillin resistant Staphylococcus aureus (MRSA) is a major human pathogen responsible for several life threatening conditions. MRSA have the ability to acquire resistance to several antimicrobial agents and phage therapy is one potential option to treat this pathogen. The aim of the study was to isolate and characterize bacteriophages effective against a wide range of methicillin-resistant Staphylococcus aureus (MRSA). A mixture of ten MRSA isolates was used for the isolation of phage from wastewater treatment plants. Three phages were selected for further characterization. All three phages belong to the Siphoviridae family and have long non-contractile flexible tails. The three phages showed a wide host range against S. aureus. Phages ɸSA1 and ɸSA2 were resistant to a pH range from 4-10 while ɸSA3 has a pH range from 3-11. DNA from all three phages was resistant to digestion by endonuclease enzymes such as EcoRI and AccI. There was a high degree of mosaicism among the three virulent phages and with their ancestor phages of Siphoviridae due to their non-uniform access to the common genetic pool by horizontal gene transfer and recombination. Since some of the staphylococcal toxins are phage encoded, the presence of genes for such toxins was tested by performing polymerase chain reaction and all three phages lacked genes for any of the staphylococcal toxins, including staphylococcal enterotoxins (sea, seb, sec and see), exfoliating toxins (eta and etb) and the toxic shock syndrome toxin (tst), therefore these bacteriophage are suitable candidates for future use in phage therapy against MRSA.