Abstract
BackgroundTo investigate antibiotic resistance, the occurrence and distribution of class 1 and 2 integrons in multidrug- resistant Staphylococcus aureus isolates from hospitals in Tehran, Iran.The isolates were examined for susceptibility to antimicrobial agents. The mecA gene, class 1 and 2 integrons were detected by PCR. Integrase positive strains were further analysed for the presence of resistance gene cassettes using specific primers and were sequenced.ResultsAmong 139 S.aureus isolates, 109 (78.4 %) and 112 (80.5 %) strains were considered as multidrug resistant and mecA positive, respectively. Class 1 integrons and internal variable regions were found in 72.6 % (101/139) and 97 % (98/101) and class 2 integrons and variable regions also in 35.2 % (49/139) and 65.3 % (32/49) of S.aureus clinical isolates, respectively. Twelve distinct cassette arrays were found, containing genes encoding resistance to β-lactams, aminoglycosides, streptothricin, trimethoprim, chloramphenicol,a putative glucose dehydrogenase precursor and a protein with unknown function. Gene cassette arrays aadB, aadA2 and dhfrA1-sat2-aadA1 were common in S.aureus isolates. We detected a completely new gene cassettes which contained aadB, oxa2, aacA4, orfD-aacA4-catB8, aadB-catB3, orfD-aacA4 and aadB-aadA1-cmlA6 of class 1 and dhfrA1-sat2-aadA1, dhfrA11, dhfrA1-sat2 of class 2 integrons.ConclusionsThis is the first study to report carriage of class 1 and 2 integrons and associated gene cassettes among in S.aureus isolates from Iran.
Highlights
To investigate antibiotic resistance, the occurrence and distribution of class 1 and 2 integrons in multidrug- resistant Staphylococcus aureus isolates from hospitals in Tehran, Iran
112 (80.5 %) isolates were resistant to methicillin and were confirmed as methicillin-resistant S. aureus (MRSA) based on the detection of the mecA gene
All MRSA isolates were resistant to Amoxicillin (100 %) and Ampicillin (100 %), Tetracycline 69 (61.6 %), Amikacin 40 (35.7 %), Ceftriaxone 68 (60.7 %), Gentamicin 73 (65.1 %), Spectinomycin 77 (68.7 %), Table 1 Correlation of antibiotic resistance between class 1 integron-positive and integron-negative of S.aureus
Summary
The occurrence and distribution of class 1 and 2 integrons in multidrug- resistant Staphylococcus aureus isolates from hospitals in Tehran, Iran. Due to an increasing number of infections caused by methicillin-resistant S. aureus (MRSA) strains, which are most often multiresistant, therapy has become problematic [4]. Since this organism can spread by direct or indirect contact between patients and the environment, or among patients and medical personnel, S. aureus is an important cause of nosocomial infection, and major outbreaks are common [5, 6].
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