The Distribution of Pathogenic and Toxigenic Genes Among Mrsa and Mssa Clinical Isolates Publisher Pubmed



Imani Fooladi AA¹ ; Ashrafi E² ; Tazandareh SG³ ; Koosha RZ⁴ ; Rad HS¹ ; Amin M⁵ ; Soori M³ ; Larki RA⁶ ; Choopani A⁷ ; Hosseini HM¹
Source: Microbial Pathogenesis Published:2015

Abstract

Staphylococcus aureus (. S.aureus) is considered as a notorious nosocomial pathogen among hospitalized patients and community-dwelling subjects. Its increasing morbidity and mortality is believed to be due to antibiotic resistance. However, the data concerning molecular properties of infecting strains are few.In this study, a total of 192 S.aureus strains, including 88 (45.8%) meticillin-sensitive S. aureus (MSSA) and 104 (54.2%) meticillin-resistant S. aureus (MRSA) were recovered from clinical samples. The prevalence of subtypes containing staphylococcal cassette chromosome mec (SSC. mec), staphylococcal enterotoxins (SEs), toxic shock syndrome toxin (TSST) and exfoliative toxin was assessed by PCR. Antibiotic susceptibility pattern and vancomycin resistance of each isolate were evaluated by disk diffusion method and micro-dilution method, respectively.9 (2.3%) strains required MIC>2mg/l of vancomycin, which significantly increased among multi drug resistant (MDR), MRSA and SCC. mec type III strains (p<0.05). 171 (89%), 140 (72.91%), 7 (3.6), 78 (48.6%), 5 (2.6%), 151 (78.64%), 129 (67.18%), 178 (92.7%) and 15 (7.8%) of 192 isolates harbored mecA, entA, entB, entC, entD, entE, eta, etb and tsst-1 genes, respectively. 31 (16.14%), 5 (2.6%), 95 (49.48%) and 7 (3.64%) of 192 isolates carried SCC. mec type I, II, III and IV, respectively. We found a significantly higher rate of MRSA and resistance to all tested antibiotics, except to penicillin G, kanamycin and linezolide among the SCC. mec type III class (p<0.05).According to our findings, MSSA isolates should be taken as seriously as MRSA strains due to the potential presence of broad spectrum virulence factor genes. © 2015 Elsevier Ltd.