Isolation, Characterization, and Antibacterial Activity of Bacteriophages Against Methicillin-Resistant Staphylococcus aureus in Pakistan

Abstract

BackgroundIn recent years, antibiotic resistance has been indicated as a paramount threat to public health. The use of bacteriophages appears to be a safer alternative for the control of bacterial infections.ObjectivesThe present study aims to explore sewage water for the presence of indigenous bacteriophages, and to investigate their antibacterial potential against Methicillin-resistant Staphylococcus aureus (MRSA).MethodsBacterial isolates were first collected and identified from pus samples taken from the surgical and burn units using standard microbiological procedures. A cefoxitin disk screen test was then used and interpreted according to the clinical laboratory standards institute (CLSI) guidelines for the detection of MRSA. The sewage samples were processed and the phages enriched using S. aureus as a host organism. Turbid and clear plaques of different sizes were isolated using an overlay method, purified, and then enumerated by means of a dilution method.ResultsThe phages exhibited good lytic activity against MRSA when tested in-vitro, and the highest activity was attained within three to six hours of phage infection. The isolated phage pq/48 was also found efficient in decreasing the bacterial count during an in-vivo trial in rabbits. A protein analysis using SDS-PAGE revealed 10 proteins of between 20 kDa and 155 kDa in size.ConclusionsThe overall results indicated that bacteriophages isolated from sewage exhibited excellent lytic activity against MRSA strains. In conclusion, bacteriophages can be further characterized and appear to be a promising candidate for phage therapy against MRSA in the future.

Efficacy of Lytic Bacteriophages against Multidrug Resistant Salmonella enteritidis from Milk and Meat

“…Similar results were reported by Robeson et al (2008) and Khalid et al (2017). All the samples collected from hospitals were found positive for bacteriophages, mainly because of presence of high bacterial contamination as reported (Rasool et al, 2016). In the recent study, to isolate and purify the bacteriophages, agar overlay method was used.…”

“…Different antibiotic disks such as amikacin (30 µg), ceftriaxone (30 µg), piperacillin and ciprofloxacin (100/10 µg) were tested. Zones of inhibition were noted after the incubation for 24 hours at 37°C and compared with CLSI scale (Beige et al, 2015;Rasool et al, 2016). While minimum inhibitory concentration was determined by Broth microdilution method according to the guidelines of Clinical Laboratory Standard Institute (CSLI) (Humphries et al, 2012).…”

“…Assessment of phages efficacy by spot assay: Spot assay was used to check the lytic activity of isolated phages and the best sewage filtrate and susceptible host were further used to check the plaque morphology using agar overlay method (Rasool et al, 2016). Well isolated plaques were selected for purification and phage count (Sangha et al, 2014).…”

“…Effect of salt on plaque morphology: Different divalent salts are considered to enhance the attachment of bacteriophages to the bacterial cell as well better intracellular progression. CaCl2 and MgSO4 were tested for their effect on plaque morphology (Rasool et al, 2016).…”

“…Most common bacteriophage families are Myoviridae, Podoviridae and Siphoviridae (Sepúlveda-Robles et al, 2012). The antibacterial activity of phages is due to the phage attachment on bacterial cells followed by changes in bacterial metabolism which leads to bacterial lysis (Rasool et al, 2016). Most of the bacteriophages are bactericidal in nature and the bacteria are incapable of recovering their viability following phage therapy along with minimum risk of secondary bacterial infection due to high specificity of bacteriophages against bacteria (Skurnik et al, 2007;Zhang et al, 2017).…”