Mahtab Tabandeh1, Hami Kaboosi2, Mojtaba Taghizadeh Armaki3, Abazar Pournajaf4, Fatemeh Peyravii Ghadikolaii5. 1. Department of Microbiology, Ayatollah Amoli Branch, Islamic Azad University, Amol, Iran. 2. Department of Microbiology, Ayatollah Amoli Branch, Islamic Azad University, Amol, Iran. h.kaboosi@iauamol.ac.ir. 3. Infectious Diseases and Tropical Medicine Research Center, Health Research Center, Department of Parasitology and Mycology, School of Medicine, Babol University of Medical Sciences, Babol, Iran. 4. Infectious Diseases and Tropical Medicine Research Center, Health Research Center, Department of Microbiology, School of Medicine, Babol University of Medical Sciences, Babol, Iran. 5. Department of Biology, Qaemshahr Branch, Islamic Azad University, Qaemshahr, Iran.
Abstract
BACKGROUND: Staphylococcus aureus is often considered as a potential pathogen and resistant to a wide range of antibiotics. The pathogenicity of this bacterium is due to the presence of multiple virulence factors and the ability to form biofilm. SCCmec types I, II and III are mainly attributed to HA-MRSA, while SCCmec types IV and V have usually been reported in CA-MRSA infections. METHODS AND RESULTS: In this study, we performed a cross-sectional study to determine the antimicrobial resistance, adhesion and virulence factors, biofilm formation and SCCmec typing of clinical S. aureus isolates in Iran. S. aureus isolates were identified using microbiological standard methods and antibiotic susceptibility tests were performed as described by the Clinical and Laboratory Standards Institute (CLSI) guidelines. Inducible resistance phenotype and biofilm formation were determined using D-test and tissue culture plate methods, respectively. Multiplex-PCRs were performed to detect adhesion and virulence factors, antibiotic resistance genes, biofilm formation and SCCmec typing by specific primers. Among 143 clinical samples, 67.8% were identified as MRSA. All isolates were susceptible to vancomycin. The prevalence of cMLSB, iMLSB and MS phenotypes were 61.1%, 22.2% and 14.8%, respectively. The TCP method revealed that 71.3% of isolates were able to form biofilm. The predominant virulence and inducible resistance genes in both MRSA and MSSA isolates were related to sea and ermC respectively. SCCmec type III was the predominant type. CONCLUSIONS: Data show the high prevalence rates of virulence elements among S. aureus isolates, especially MRSA strains. This result might be attributed to antibiotic pressure, facilitating clonal selection.
BACKGROUND: Staphylococcus aureus is often considered as a potential pathogen and resistant to a wide range of antibiotics. The pathogenicity of this bacterium is due to the presence of multiple virulence factors and the ability to form biofilm. SCCmec types I, II and III are mainly attributed to HA-MRSA, while SCCmec types IV and V have usually been reported in CA-MRSA infections. METHODS AND RESULTS: In this study, we performed a cross-sectional study to determine the antimicrobial resistance, adhesion and virulence factors, biofilm formation and SCCmec typing of clinical S. aureus isolates in Iran. S. aureus isolates were identified using microbiological standard methods and antibiotic susceptibility tests were performed as described by the Clinical and Laboratory Standards Institute (CLSI) guidelines. Inducible resistance phenotype and biofilm formation were determined using D-test and tissue culture plate methods, respectively. Multiplex-PCRs were performed to detect adhesion and virulence factors, antibiotic resistance genes, biofilm formation and SCCmec typing by specific primers. Among 143 clinical samples, 67.8% were identified as MRSA. All isolates were susceptible to vancomycin. The prevalence of cMLSB, iMLSB and MS phenotypes were 61.1%, 22.2% and 14.8%, respectively. The TCP method revealed that 71.3% of isolates were able to form biofilm. The predominant virulence and inducible resistance genes in both MRSA and MSSA isolates were related to sea and ermC respectively. SCCmec type III was the predominant type. CONCLUSIONS: Data show the high prevalence rates of virulence elements among S. aureus isolates, especially MRSA strains. This result might be attributed to antibiotic pressure, facilitating clonal selection.
Authors: Steven Y C Tong; Joshua S Davis; Emily Eichenberger; Thomas L Holland; Vance G Fowler Journal: Clin Microbiol Rev Date: 2015-07 Impact factor: 26.132