Prevalence of Antibiotic Resistance Determinants in Carbapenem-ResistantPseudomonas aeruginosa: Focus on Class 1 and 2 Integrons and blaIMP Gene

Document Type : Original Article

Authors
Maryam Behboudipour 1
Neda Soleimani 2
Negar Azarpira 3
Neda. Soleimani 4 , 5
1 Department of Microbiology and Microbial Biotechnology, Faculty of Life Sciences and Biotechnology, Shahid Beheshti University, Tehran, Iran
2 Department of Microbiology and Microbial Biotechnology, Faculty of Life Sciences and Biotechnology, Shahid Beheshti University, Tehran, Iran.
3 Transplant Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
4 Transplant Research Center, Shiraz University of Medical Sciences, Shiraz, Iran.
5 Department of Pathology, Shiraz Medical School, Shiraz University of Medical Sciences, Shiraz, Iran .
10.22088/IJMCM.BUMS.14.3.886
Abstract
As a leading non-fermentative opportunistic bacterium, Pseudomonas aeruginosa (P.
aeruginosa) plays a major role in healthcare-associated infections. The emergence of
carbapenem-resistant strains is a serious clinical threat, often associated with integrons
and carbapenemases such as blaIMP. The present study aimed to assess the distribution
of class 1 and 2 integrons and the blaIMP gene among clinical isolates of carbapenem-
resistant P. aeruginosa from hospitals in Shiraz.
Seventy clinical isolates of P. aeruginosa were collected from different hospital wards.
The identification of the isolates was performed using common microbiology methods.
The disk diffusion method was used to evaluate the antimicrobial susceptibility.
Minimum inhibitory concentration (MIC) values for imipenem in carbapenem-resistant
strains were obtained using E-test strips. Polymerase chain reaction (PCR) was used to
identify the resistance determinants including intI1, intI2, and blaIMP.
Of the 70 clinical isolates, 35 (50%) isolates were imipenem-resistant. MIC testing
showed that 34 isolates had a resistant MIC (MIC ≥ 8 μg/mL). PCR results showed that
33 (94.3%) isolates carried the intI1 gene and 17 (48.6%) isolates carried the blaIMP
gene. Co-existence of intI1 and blaIMP genes was observed in 17 (48.6%) isolates. The
intI2 gene was not detected in any of the samples. The prevalence of the intI1 and blaIMP
genes was higher among the isolates obtained from intensive care units (ICU) and
internal medicine wards.
The high prevalence of class 1 integrons and the blaIMP gene among carbapenem-
resistant isolates suggests the key function of mobile genetic elements in the horizontal
spread of resistance factors.

Keywords
Integrons
Drug Resistance
Carbapenemase
Pseudomonas aeruginosa