Mahsa Yazdi, Ali Nazemi, Mir Saed Mir Nargasi, Mr Khataminejad, Sh Sharifi, M Babai Kochkaksaraei,
Volume 4, Issue 1 (4-2010)
Abstract
Abstract Background and objectives: Beta-lactamase enzymes are the most causes of resistance to antibiotics among gram-negative bacteria. Nowadays, Infections due to ESBLs are being increased throughout the world and is considered as a new burden to the health systems. This study aimed at determining the sensitivity pattern of E.coli isolates to beta-lactam antibiotics, and investigating the presence of blaCTX-M, blaTEM, and blaSHV genes in the urine samples. . Material and Methods: In this study, 244 E.coli isolates were screened in 2009-2010. The antibiotic susceptibility of E. coli isolates were determined by disc-diffusion method. Antimicrobial agents tested were cefoxatime, ceftazidime, imipenem, nalidixic acid, and ciprofloxacin. The combined disc test was used to confirm the results. The results were compared to the Clinical and Laboratory Standards Institute (CLSI) and ESBL positive isolates were further investigated for the presence of blaCTX-M, blaTEM, and blaSHV genes by PCR. Results: Of 244 E. coli isolates, 116 (47.1%) are resistant to Ceftazidime, and 96 (39.2%) to cefoxatime. Also, 109 (44.3%) isolates are ESBL positive. blaCTX-M, blaTEM, and blaSHV genes are found among 95 (87.1%), 75 (68.8%), and 77 (70.6%) ESBL positive isolates, respectively. Forty (36.6%) isolates have all three genes, while 68 (62.3%) include blaTEM and blaSHV genes. Moreover, 61 (55.9%) isolates carry blaCTX-M and blaTEM genes, and 54(49.5%) have blactx-M and blashv. Conclusion: Regarding the high frequency of resistance to the third generation cephalosporin antibiotics, precise antibiogram testing is highly recommended before any antibiotic prescription in cases of infections with ESBL producing microorganisms. Key words: ESBL Escherichia coli blaCTX-M blaTEM blaSHV.
Majid Komijani , Majid Bouzari , Fateh Rahimi ,
Volume 11, Issue 2 (3-2017)
Abstract
ABSTRACT
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.
Keywords: Antibiotic resistance genes, ESBL, TEM, SHV, CTX-M, Escherichia coli.
