Majallah-i Dānishgāh-i ̒Ulūm-i Pizishkī-i Bābul (Mar 2017)
Molecular Identification of Genes Responsible for Resistance to Aminoglycosides and Methicillin in Clinical Samples of Staphylococcus Aureus
Abstract
BACKGROUND AND OBJECTIVE: Staphylococcus aureus is one of the most important causes of infection in the hospital and the community. Resistance to aminoglycosides is caused by certain enzymes, which are coded by the genes with the ability of intrastrain circulation by mobile genetic elements such as transposons. This study aims to to determine the frequency of aac (6 ') Ie / aph (2 "), aph (3') - IIIa1, ant (4 ') - Ia1 genes along with mecA gene. METHODS: In this cross sectional study, 113 Staphylococcus aureus strains were isolated from 579 various clinical samples. The Method of determining the minimum inhibitory concentration was used to identify the genes resistant to aminoglycosides by Oxacillin Etest strips. PCR method was used to identify aac (6 ') Ie / aph (2 "), aph (3') - IIIa1, ant (4 ') - Ia1and mecA. The relationship between aminoglycosides and mecA genes was also investigated. FINDINGS: Of 113 clinical isolates of Staphylococcus aureus confirmed by phenotypic tests, 53 isolates (46.91%) had mecA gene, 43 isolates (38.05%) had aac (6 ') Ie / aph (2 ") gene, 19 isolate (16.81%) had aph (3') - IIIa1 gene and 22 isolates (19.47%) had ant (4 ') - Ia1 gene. In addition, there was a significant relationship between the presence of Methicillin-resistant gene and genes responsible for resistance to aminoglycosides. Meanwhile, there was also a significant relationship between the type of isolated samples and the presence of resistance genes in some cases (p≤0/005). CONCLUSION: Results of the study demonstrated that frequent use of the aminoglycoside antibiotics along with beta-lactam antibiotics might provide the context for the emergence of multi-drug-resistant Staphylococcus aureus (MDR) strains. By appropriate and controlled administration of antibiotics, we can decrease such resistances and prevent the emergence of multi-drug-resistant Staphylococcus aureus strains.
