CTX-M

Background: This prospective study investigated major characteristics of E.coli colonizing the intestine of out-and in-patient infants, especially their association with CTX-M-type extended spectrum β-Lactamases (ESBLs), integrons and fluoroquinolones-resistance.

Background and Objective: Escherichia coli is one of the most common causes of hospital-acquired infections. Extended-spectrum β-lactamase (ESBL)-producing E. coli strains are resistant to third-generation cephalosporins. The three main genes involved in ESBL production are TEM, SHV and CTX-M. Detection of ESBL-producing E. coli is of importance for infection control, reduction of excessive antibiotic use and epidemiological surveillance. This study aimed to detect ESBL-producing E. coli strains isolated from wound infections using phenotypic and molecular methods. Methods: During 2013-early 2015, 86 strains were collected from three hospitals in Isfahan, Iran. Antibiotic susceptibility testing was done using ceftazidime and ceftazidime + clavulanic acid discs. Polymerase chain reaction was used for the detection of the three resistance genes. Results: The resistance genes SHV, CTX-M and TEM were detected in 49 isolates (56.9%). In addition, 39 isolates (45%) were ESBL-producing strains. According to the results, 5 (5.8%), 14 (16.2%), 19 (22%) and 11 (12.7%) isolates contained the SHV, CTX-M, TEM and CTX-M + TEM genes, respectively. The frequency of CTX and TEM were significantly higher than that of SHV gene (P <0.05). Most of the isolated bacteria were resistant to cefazolin and sensitive to nitrofurantoin. Conclusions: There is a difference between the frequency of ESBL-positive isolates reported in the phenotypic and genotypic methods, which could be due to the lower sensitivity of the phenotypic method and impact of environmental factors on the emergence of antibiotic resistance.

A  total  of 150  urine  samples collected from Dogs, Cats and Human were    immediately  transported to the laboratory for analysis and diagnosed on the basis of clinical  symptoms, microscopy  , culture by convential methods,  and Confirmed by  Rapid API 32E  and  VITEK-2 automated system. Vitek 2 was also used determine the susceptibility of isolates to antimicrobials. Antibiotic susceptibility tests  were performed on all  positively confirmed isolates. In addition, Klebseilla spp. isolates were tested for CTX-M  genes by PCR.
Out of 150 urine samples  120 (80%) patients tested    positive for culture.86 samples (57.3%)  was  of  the family Enterobacteriaceae.  E.coli was the most common isolate causing UTI  (49.8%)  followed    by Klebsiella spp. (16.4%)    then  Proteus spp.  (3.9%)  and Pseudomonas spp. (2%). The 58 strains of E. coli isolated were submitted to serotyping for O antigens. Antibiotic susceptibility tests  were performed on all  positively confirmed isolates. 62.7 % of the isolates, were resistant to three or more different classes of agents, and were considered to present MDR.  High level of resistance was seen to Trimethoprim-sulfamethoxazole, cephalosporins, Penicillin,  Gentamicin.  However Imipenem was found to be highly sensitive to most urinary isolates of  multidrug resistant strains. MDR was found in 48 (82%) of E. coli and in 15 (78%) of Klebsiella spp. Isolates and in all (100%) of Proteus spp and in all Pseudomonas isolates. ESBLs were detected phenotypically in 17 (89%) of Klebsiella spp. isolates. Fourteen (73.7%) out of 19 samples of phenotypically ESBL-positive K. pneumoneae were positive for ESBL CTX-M gene by PCR.