valuation of some viral kinetics of Lytic Bacteriophages Infecting Methicillin Resistant Staphylococcus aureus (MRSA)

Abstract

   Background:

Bacteriophages represent important groups of viruses that drive the bacterial populations in the ecosystems directly and control their numbers, unlike antibiotics they can kill the bacterial host without damaging or any harm to the normal microbial flora, so bacterial resistance to antibiotics is no more valuable problem if the use of phages becomes more efficient in use.

Aim:

The purpose of this study was to isolate and characterizing the phages that  able to infect methicillin resistant Staphylococcus aureus (MRSA) and determination of phages kinetics.

Methods:

Different techniques were used to isolate and propagate the MRSA phages, then phage kinetics were determined such as adsorption rate, eclipse period, burst size , phage host range, phage sensitivity to pH and temperature and the determination of phage nucleic acids.

Results:

Two types of anti-staphylococcal lytic bacteriophages primarily named Phage 1 and Phage 2 were isolated from sewage water. Phage 1 exhibited broad host spectrum it was lytic against all S. aureus isolates included for the study. Conversely, phage 2 have narrow host range as they could inhibit only 30 isolates, None of these phages inhibited a bacterium other than staphylococci species. The adsorption rate of Phage 1 was 2.1×10^-10 ml min^-1 while Phage 2 was 1.5×10^-10 ml min^-1. Eclipse and Latent periods of Phage 1 were 6, 13 minutes and for phage 2 were 8, 16 minutes respectively, the burst size of Phage 1 and Phage 2 were 83±15 pfu\cell and 37±10 pfu\cell respectively. Complete lysis time of Phage 1 particles was 4 hours while the complete lysis time of Phage 2 particles was 5 hours. Phages passaging results showed a remarkable increment in plaque forming unit (pfu) which were reached its maximal elevation at six passage in Phage 1 and fourth passage in Phage 2. Fitness of Phage 1 and Phage 2 were 22 ± 5 pfu\cell and 20 ± 2 pfu\cell respectively through six generations. The Phage 1 and Phage 2 particles were stabled at a wide range of pH (6-10) and temperatures (30-50°C), the optimal temperature of two phages were 37°C.

Conclusion:

Overall findings suggested that MRSA phages are well distributed in the environment and represent a good and promising tool to control the infections result by this bacteria in which antibiotic resistance will be overwhelmed successfully especially in external infections such as burns and skins infections, which are safe and very specific with less side effects than antibiotic.