Prevalence and Molecular Characteristics of Carbapenemase-Producing Enterobacteriaceae Among Intensive Care Unit patients: A Cross-Sectional Study in North of Iran

Abstract

Background: Carbapenems are often used as last-line agents for treating serious healthcare-associated infections (HCAIs) caused by multidrug-resistant strains. Moreover, increasing resistance to this class of antibiotics has been a major concern worldwide. In the present study, we report the prevalence and molecular characteristics of CPE among intensive care unit patients from university hospitals in Sari, North of Iran. Materials and Methods: One hundred non-repeated clinical specimens were obtained from hospitalized patients in ICUs of four teaching hospitals in Sari, North of Iran. The API 20E system was used to identify the Enterobacteriaceae. Antibiotic susceptibility testing was performed by the disk diffusion and E-test methods. Subsequently, the MHT and CDT tests were used to identify carbapenemase- producing clinical isolates, and polymerase chain reaction (PCR) was used to detect the presence of NDM-1, VIM, and OXA-48 genes in the isolates’ chromosomal DNA. Results: The most enterobacterial isolates in the present study included Escherichia coli (37%), Klebsiella pneumoniae (21%), and Serratia rubidaea (10%), respectively. The most and least effective antibiotics against the clinical isolates were amikacin and meropenem, with resistance rates of 24% and 73%, respectively, while 51% of the isolates were imipenem-resistant. Also, 58 isolates were detected as multi- drug resistant (MDR) of which all of them were carbapenem-resistant. Among 73 carbapenem-resistant isolates, 35 (47.9%) and 33 (45.2%) of them were MHT and CDT positive, respectively. Moreover, 30.1%, 31.5%, and 38.3% of these isolates contained VIM, NDM-1, and OXA-48 carbapenemase encoding genes, respectively. Conclusions: This work demonstrates that the MHT is not a reliable test for the study of strains producing OXA-48 or VIM carbapenemases. Additionally, there was a significant association between the presence of carbapenem resistance genes and K. pneumoniae isolates. It seems that the presence of at least two of these genes can be one of the main reasons for resistance to carbapenems in Enterobacteriaceae