Molecular detection and production of microcin from Escherichia coli isolated from different clinical samples
علاء عبد الرزاق محمد حسين, محمد صبري عبد الرزاق
كلية الطب-جامعة بابل · العراق
In this study, a total of 100 samples were obtained from patients suffering from urinary tract infection who attended Al-Husain General Teaching Hospital in Kerbala province in a period ranging from October 2012 to January 2013. The patients’ age ranged from 15 years to 78 years. Only 30 isolates of E. coli were isolated and diagnosed. The isolates were subjected to susceptibility testing to antibiotics by the modified Kirby-Bauer disc diffusion method. The results showed that all of these isolates were completely sensitive (100%) to imipenem and 97% to chloramphenicol. Isolates also showed 73% sensitivity for norfloxacin and 46% for gentamicin. The study also showed that the isolates were resistant to Amikacin (90%), Piperacillin/Tazobactam (89%), Co-Trimoxazole (82%), and Amoxyclav (86%), while resistance was observed for Erythromycin (64%), tetracycline (45%), Tobramycin (58%), and Ampicillin (71%). Molecular detection for microcin genes was done using specific PCR primers to investigate the presence of these genes in bacteria. The Catechol microcin (mchC) gene was detected in all isolates, and microcin H47 (mchB) was investigated and found in only seven isolates, representing 100% of all isolates. Molecular detection of genes responsible for microcin M (mcmi, mcmA, and mcmIA) production was found only in five isolates (17.6% for mcmi, 5.8% for mcmA, and 5.8% for mcmIA). Microcin I47 was found in only one isolate (5.8% for mciA). Molecular detection of the gene of Microcin J25 was found in only one isolate (5.8% for J25). Also, the mccF gene (C7 Microcin) was found in only one isolate (5.8% for mccF). The gene (mceA), responsible for Microcin E492, showed negative results for all isolates. On the other hand, E. coli was tested for its ability to produce microcin using a special medium (M63). The results showed that microcin was produced at a high level simultaneously with other bacteriocins produced by this bacterium. However, a cellophane membrane was used to separate microcin from other bacteriocins, and the former was subjected to partial purification using ammonium sulfate fractionation and dialysis. The result of ammonium sulfate treatment led to an increase in microcin activity.