Golnar Rahimzadeh - Pediatric Infectious Diseases Research Center, Mazandaran University of Medical Sciences, Sari, Iran|Student Research Committee, Mazandaran University of Medical Sciences, Sari, Iran
Pooria Gill - Nanomedicine Group, Immunogenetics Research Center, Mazandaran University of Medical Sciences, Sari, Iran
Mohammad Sadegh Rezai - Pediatric Infectious Diseases Research Center, Mazandaran University of Medical Sciences, Sari, Iran

Objective(s): During the last years with increasing resistant bacteria to the most antibiotics bacteriophages are suggested as appropriate treatment option. To investigate lytic activity of bacteriophages there are indirect microbial procedures and direct methods. The present study to complement microbial procedures and investigate ultra-structural characteristics of infection bacterium-phage use atomic force microscopy technique.Materials and Methods: The Siphoviridae bacteriophages were isolated from sewage at the Tertiary Pediatric Hospital. Bacteriophages (10×108 PFU/ml) were diluted and were mixed with 100 μl of methicillin resistant Staphylococcus aureus (MRSA) ATCC 33591 (1.5×108 CFU/ml). The tubes were incubated for 20 min at 37 °C, at intervals 10 min, 10 μl samples were removed and directly were investigated MRSA ATCC morphology, roughness parameter, 3D topography, cell height, and fast Fourier transform (FFT) by atomic force microscopy (AFM) technique. Concurrently turbidity assay were performed.Results: Concentration of MRSA ATCC No. 33591 strain after 10 min in phage-treated MRSA S3 (1.5×106 CFU/ml), S4 (1.5×105 CFU/ml), S5 (1.5×104 CFU/ml), S6 (1.5×103 CFU/ml) decreased 2-log, 3-log, 4-log, and 5-log respectively. The results AFM micrographs shown the most changes in bacterial morphology and 3D topography, destruction of cell wall, decrease of cell height, and loss of their shape after 10 min at phage-treated MRSA S3 (1.5×106 CFU/ml), S4 (1.5×105 CFU/ml), S5 (1.5×104 CFU/ml), S6 (1.5×103 CFU/ml) respectively .Conclusion: In this study MRSA ATCC ultra-structural changes in phage-treated MRSA ATCC groups directly were detected using AFM technique.

AFM, Bacteriophages, Lytic activity, MRSA, 3D Topography