Background and purpose: Extended spectrum beta lactamases (ESBLs) are important causes of multidrug resistance (MDR) Escherichia coli. ESBL genes are usually located on conjugative plasmids or on integron structures. The aim of this study was to detect ESBLs on class I integron in Escherichia coli isolated from clinical samples.

Materials and methods: A descriptive cross-sectional study was performed in which 60 isolates of E. coli were collected from two hospitals in Kerman, Iran during three months. The isolates were identified using standard microbiological and biochemical techniques. Antibiotic susceptibility pattern of isolates was determined by disk agar diffusion method. ESBL-producing E. coli was determined using phenotypic double disc test. Then, Polymerase chain reaction (PCR) was used to detect intI, bla-TEM, bla-SHV, and bla-CTX-M genes. Data analysis was done in SPSS applying Chi-square test.

Results: The highest and lowest rates of antibiotic sensitivities in isolated E. coli were found to amikacin and imipenem (3.3%) and ampicillin (66.6%), respectively. Multidrug resistance was detected in 43.3% of the samples. 45% of isolates were identified as ESBL producers. Prevalence of bla-TEM, bla-CTX-M and bla-SHV genes were 74.07%, 69.9%, and 7.4%, respectively. Class I integron was detected in 60% of the isolates.

Conclusion: In this study, we observed a significant association between ESBL and class I integron which confirms that ESBLs were located on integron class I and easily transferred into bacteria.