الفهرس 
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Abstract
E. coli ST131 has emerged as a global epidemic, multidrug-resistant clone of E. coli causing extra-intestinal infections. It is highly prevalent among fluoroquinolone-resistant and ESBL-producing E. coli isolates worldwide. Humans are likely the primary reservoir of ST131.
E. coli ST131 causes a wide range of infections ranging from cystitis to life-threatening sepsis. Phenotypic detection of the ST131 clone is not possible and DNA-based techniques, including MLST and PCR, are described.
UTI is one of the most common bacterial infections and accounts for significant morbidity and mortality with high medical costs. Although fluoroquinolones are particularly useful for the treatment of UTIs, because high concentrations in the urine can be achieved and their broad-spectrum activity, however fluoroquinolones and trimethoprim-sulfamethoxazole are no longer adequate options for empiric therapy when E. coli ST131 is suspected from local epidemiology. Expanded-spectrum cephalosporins, piperacillin-tazobactam and carbapenems are options to treat serious non-ESBL-producing E. coli ST131 infections, while carbapenems are indicated for ESBL-producing infections. There is a growing interest in re-evaluating oral agents including fosfomycin for less serious infections such as uncomplicated cystitis.
The objective of this study was to assess the presence of the two main subgroups of ST131 E. coli (O25/O16) in a group of E. coli isolates from cases of community acquired UTI as well as to investigate its association with fluoroquinolone resistance and ESBL production in order to obtain an estimate of its prevalence and to choose an appropriate anti-microbial therapy for patients infected by such bacteria.
This study was conducted on thirty E. coli isolates from urine specimens of cases of community acquired urinary tract infections obtained from the bacteriology Laboratories of Ain Shams University hospitals and Microbiology Department lab of Ain Shams Faculty of Medicine during the period from April to June 2017.
All isolates were identified by conventional microbiological methods. Isolates were tested for fluoroquinolone resistance using four different fluoroquinolones antibiotics by Kirby Bauer disk diffusion method and extended spectrum beta lactamases (ESBL) production using the disc diffusion test (screening test) and the double disc synergy test (confirmatory test). A multiplex PCR was done to detect pabB gene and trpA gene for O25b/O16 subgroups of E. coli ST131 respectively.
The results of this study are summarized as follows:
• Of the 30 E. coli isolates tested for antimicrobial resistance, 14 (47%) were found resistant to fluoroquinolones
• 7 out of 30 isolates (23.3%) were positive for ESBL production.
• ST131-O25b (pabB gene) was detected in fifteen (50%) isolates while the ST131-O16 subgroup was not detected (trpA gene) in any of the studied isolates.
• O25-ST131 E. coli isolates showed high rate of resistance to the tested antimicrobials (nalidixic acid, ciprofloxacin, norfloxacin, levofloxacin, ceftazidime, cefotaxime, ceftriaxone, cefpodoxime and aztreonam,) in comparison to non O25-ST131 E. coli isolates
• Among E. coli isolates, there was a significant correlation between fluoroquinolone resistance and O25-ST131 detection.
• There was no significant relation between ESBL production and O25-ST131 detection, although there was a higher rate of ESBL production among O25-ST131 isolates.
• There was a significant correlation between fluoroquinolone resistant non ESBL producer isolates and O25-ST131 detection.