Investigation of Integron Classes 1, 2, and 3 Among Multi-Drug Resistant Staphylococcus Aureus Isolates in Iran: A Multi-Center Study Publisher Pubmed

Summary: Research in Iran found high rates of MRSA and drug resistance in S. aureus. Some strains carried resistance genes, raising concerns for treatment. #AntibioticResistance #InfectiousDisease

Zomorodi AR^{1, 2} ; Motamedifar M³ ; Rahmanian K⁴ ; Shakeri M⁴ ; Hajikhani B⁵ ; Heidari H⁶ ; Mansury D⁷ ; Jahromi AS⁴
Source: BMC Infectious Diseases Published:2024

Abstract

Background: Rising methicillin-resistant Staphylococcus aureus (MRSA) poses a global health threat, contributing to serious infections with high mortality rates. Integrons are recognized as significant genetic elements in disseminating multidrug-resistant (MDR) strains. This study focuses on assessing the prevalence of integron classes 1, 2, and 3 in S. aureus strains from four major cities in Iran. Methods: This cross-sectional study analyzed 183 S. aureus isolates from Shiraz, Tehran, Isfahan, and Yazd in Iran. The isolates were identified using specific biochemical and molecullar tests. The Kirby-Bauer disc diffusion method and microbroth dilution method were employed to determine the susceptibility of the isolates to relevant antibiotics and vancomycin, respectively. The macrolide-lincosamide-streptogramin B (MLSB) resistance phenotype was also evaluated using the D-test. All isolates were sought for presence of the intI1, intI2, and intI3 genes. Results: Among 183 S. aureus isolates, high resistance rates were noted: 86.3% for erythromycin, 66.1% for ciprofloxacin, and 61.7% for clindamycin, while all isolates were susceptible to linezolid and vancomycin. Of the 183 isolates, 59.6% were identified as MRSA and 78.1% as MDR. According to the D-test results, 112/183 (61.2%), 29/183 (15.8%), 25/183 (13.7%), and 17/183 (9.7%) of S. aureus isolates showed constitutive resistance-MLSB, inducible resistance-MLSB, sensitive, and resistance to macrolide-streptogramin B (MS) phenotypes, respectively. The intI1 gene was found in 14 out of 183 S. aureus isolates (7.6%), while none were positive for the intI2 or intI3 genes. Notably, 11/14 (78.5%) and 13/14 (92.8%) intI1-positive isolates were MRSA and MDR, respectively. Conclusions: The distribution of MRSA and MDR S. aureus isolates in Iran seems concerning. Although the prevalence of intI1 was not as high as in prior studies, almost all S. aureus harbored the intI1 gene were MRSA and MDR. © The Author(s) 2024.