Characterizing a Lytic Bacteriophage Infecting Methicillin-Resistant Staphylococcus aureus (MRSA) Isolated From Burn Patients

Abstract

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is a significant threat to human health. It is a multidrug-resistant (MDR) pathogen capable of causing a variety of diseases. Also, MRSA is one of the most important nosocomial pathogens in burn infection. As a treatment strategy against MRSA infections, phage therapy has the potential of becoming an alternative remedy. Objectives: The present study aimed to isolate and characterize a lytic bacteriophage from hospital sewage to be effective against burn wound-infecting MRSA isolates. Methods: Staphylococcus aureus strains were isolated from hospitalized burn patients. The strains were confirmed as MRSA by the Kirby-Bauer disk diffusion method using penicillin, methicillin, and oxacillin, as well as the PCR assay for the mecA gene. The phage was isolated from the hospital sewage and tittered by the double layer agar (DLA) method. The spot test was used for host range determination. The latent period and burst size were estimated from a one-step growth curve. The phage morphology was observed by electron microscopy. The nature of the nucleic acid of the isolated bacteriophages was confirmed by Rnase A, Dnase I, and six restriction enzymes. Results: The titer, latent period, and burst size of the isolated phage were determined to be 1 × 10 9 PFU/mL, 20 min, and 190 PFU per infected cell, respectively. It displayed a broad host range for MRSA bacteria by the spot test (27 out of 30 isolates). Electron microscopy observation demonstrated that the phage belonged to the Myoviridea family. Digestion profiles of Rnase A, Dnase I, and six restriction enzymes in 1% agarose gel electrophoresis showed that the genome of the isolated phage was a double-stranded DNA with a size of <~23 kbp. Conclusions: The isolated phage (MH-1) was active against a wide range of MRSA strains recovered from burn patients. Its specificity and remarkable lytic effects on MRSA strains emphasized that it could be a suitable candidate for use in prophylaxis and treatment of these clinical infections.

Isolation and characterization of lytic bacteriophages from sewage at an egyptian tertiary care hospital against methicillin-resistant Staphylococcus aureus clinical isolates

“…This enrichment step for phage amplification was repeated three times. The phage filtrate (supernatant lysate) was stored in a dark bottle at 4 °C till needed for work to be examined for lytic phages using spot assay and plaque assay ( Hallajzadeh et al, 2020 ). For long-term storage, 0.5 ml of phage lysate was mixed with 0.5 ml sterile glycerol to obtain a final concentration of 50%, and stored at −70 °C.…”

Biological characteristics and anti-biofilm activity of a lytic phage against vancomycin-resistant Enterococcus faecium

“…One ml of filtrated lysate and 500 µl of overnight VREfm2 culture were added to melted BHI soft agar (0.5 mM MgSO , 0.7% wt/ Table 1. The Primer sequences used in the multiplex PCR assay deh et al (21). Briefly, 10 µl of the purified phage particles was poured on the surface of a carbon-coated copper grid for 3-5 min and then negatively stained by 1% (w/v) uranyl acetate (pH 7).…”