Bacteriolytic Activity of Coliphages on Diarrhea Associated E. coli

There has been an alarming increase in drug-resistant strains of diarrheagenic Escherichia coli (DEC) in developing as well as developed countries. Several cases of antimicrobial resistance in DEC have been observed in different parts of the world as a result, there has been a renewed interest in alternative antimicrobial treatments, including bacteriophages. This study was conducted to isolation and characterization of a lytic coliphage from sewage water capable to infect a variety of multidrug resistance DEC strains isolated from children suffering diarrhea, as first step to further usage a lytic coliphage in future.in this study, a coliphage was isolated using spotting method and titrated, using agar overlay technique. The host range of coliphages was assessed on a lawn of E coli bacteria. This study included determination of the latent periods and burst size of coli phage then determines the stability of coliphages to physical and chemical condition (temperature, pH and sunlight exposure).The results shown that, five phages isolate (A, B, C, D and E) were exhibiting a potent lytic activity with clear plaques (1-4mm in diameter). Fifty percent of the E coli strains were infected by phage isolates. It seems, very likely, that the coliphages belonging to 3 different groups (1, 2 and3). The phage growth cycle with a detected latent period of 20 min, a burst size of 160 plaque forming units per infected cell, it was found that the phage could survive at varied pH conditions with reduction in its numbers. A temperature of above 60°C and direct sunlight beyond 8 days was found to be deleterious for survival of the phage. Keywords: key words, coliphages, E. coli, diarrhe

Molecular characterization of Pseudomonas aeruginosa Isolates Isolated from Clinical Patients by Using RAPD-PCR Technique.

The aim of the present study was the molecular characterization and the evaluation of variability and genetic relationship of six Pseudomonas aeruginosa isolates using PCR-based Randomly Amplified Polymorphic DNA (RAPD) technique. A total number of 86 samples were collected from patients that hospitalized in Tikrit Teaching Hospital in Tikrit city. These samples were taken from patients basing on the sources of infections, the isolates were taken from: wounds, ear, burns, urine, sputum, and eyes infections. Using enrichment, selective media, and biochemical tests, that characterized and identified as P. aeruginosa. Genomic DNA was extracted from six P. aeruginosa isolates isolated from these different sources. These genomic DNA samples were found to have a suitable concentration and purity for RAPD-PCR analysis. RAPD-PCR technique was performed using 15 different Operon random primers. Eleven primers gave successful amplification results in repeated experiments. As a result, the total number of amplified bands was 270 and the total number of polymorphic bands was 234. The highest number of polymorphic bands (39 bands) was produced by primer OPX-01. The primer efficiency ranged from 3.70 (primer OPA-11) to 14.44 (primer OPX-01) and the discriminatory value ranged from 1.70% (primer OPA-11) to 16.66% (primer OPX-01). In addition, genetic distance and cluster analysis among different P. aeruginosa isolates were estimated by using UPGMA computer program basing on RAPD-PCR banding patterns that obtained in this study. These results suggesting that possible and frequent occurrence of mutations in DNA sequencing P. aeruginosa bacteria from different sources and locations. This study has proved existence genetic differences (DNA polymorphism) among the six P. aeruginosa isolates isolated from different sources. Therefore, we can say that RAPD technique could be an efficient technique for studying the molecular characterization and the epidemiology of P. aeruginosa bacteria