Antibiotic Sensitivity and Antibiotic Resistance Genes in E. coli Isolated from Human Patients; Detection of Beta-Lactamase Producing E. coli

Abstract

The main purpose of this research work was to study the antibiotic resistance and β lactamase (ESBL and AmpC) production in E. coli isolates from human patients. Aother objective was to also study the phylogenetic groups of the recovered E. coli isolates. Forty urine samples were collected from patients suspected of having urinary tract infection (UTI) at the Islamabad Diagnostic Center (IDC), Islamabad. These samples were cultured on different laboratory media and from all the 40 urine samples only E. coli was recovered. This was confirmed by growth characteristics on laboratory media and by the uidA gene PCR. The antibiotic sensitivity pattern of the E. coli isolates was determined against 14 antibiotics. The highest resistance was recorded for Ampicilin (85%), Ciprofloxacin and Levofloxacin (62.5%). The isolates showed lowest resistance against Minocycline (0%), Meropenem (2.5%) and Sulzone (2.5%). Resistance of E. coli isolates against Cefpodoxime and Cefoxitin was used to screen potential producers of ESBLs and AmpC β-lactamases. Twenty-four isolates were resistant against Cefpodoxime of which five E. coli isolates were found to be resistant to Cefoxitin. Twenty-four isolates were further tested for production of ESBLs and AmpC using a commercial AmpC and ESBL Detection Disc Set (MAST Group Ltd, UK). Two E. coli isolates out of the 5 cefoxitin resistant was confirmed to be positive for production of AmpC; while 14 out of the 24 cefpodoxime resistant isolates were confirmed positive for ESBL production. PCR were done to screen the isolates for some selected β-lactamases (ESBL & AmpC) genes in the E. coli isolates. blaCTX-M (ESBL gene) was found to be present in 16 isolates, while no bla SHV and bla TEM was found in E. coli samples. On the other hand, AmpC genes: AmpC-MOX, AmpC-CIT and AmpC-FOX were found to be present in 3 of the isolates. No AmpC-EBC, AmpC-ACC and AmpC-DHA genes were detected in any of the isolates. A triplex PCR was conducted to investigate the phylogroup of the E. coli isolates. The highest number of E. coli isolates were found to belong to group B1 (33%), followed by group A (32%), phylogroup B2 (30%) and phylogroup D (5%). xii The growing reports on ESBL producing E. coli poses a major public health threat, because, the ESBL production genes can be transferred to other bacteria including pathogens of humans through horizontal transfer by plasmids, especially, conjugative ones which can lead to resistance against multiple antibiotics. Thus, many human pathogens can become resistant to antibiotics and treatment can become difficult. Finally, there is need of research to find novel antibiotics and their rational use is needed for the future.