Several Virulence Factors of Multidrug-Resistant Staphylococcus aureus Isolates From Hospitalized Patients in Tehran

Abstract

Background: Biofilm formation plays an important role in resistance of Staphylococcus aureus isolates; especially multidrug-resistant isolates are a threat to healthcare settings. Objectives: The aims of this study were to detect biofilm formation and presence of several related genes among multidrug-resistant (MDR) isolates of Staphylococcus aureus. Patients and Methods: A total Of 209 S. aureus strains were isolated from patients and identified by conventional diagnostic tests. The multidrug-resistant MRSA isolates were detected by antibiotic susceptibility test. The phenotypic biofilm formation was detected by microtitre tissue plate assay. The polymerase chain reaction (PCR) was performed to detect the mecA, Staphylococcal Cassette Chromosome mec (SCCmec) types, accessory gene regulatory (agr) genes, the icaADBC and several genes encoding staphylococcal surface proteins including clfAB, fnbAB, fib, eno, can, ebps and bbp genes with specific primers. Results: Sixty-four (30.6%) isolates were methicillin-resistant, among which thirty-six (56.2%) were MDR. These isolates were resistant to amoxicillin, tetracycline, ciprofloxacin, gentamicin, erythromycin and trimethoprim-sulfamethoxazole (except to 6 isolates). All the isolates were susceptible to vancomycin and linezolid. All the MDR-MRSA harbored SCCmec type III. All the MDR-MRSA isolates were strong biofilm producers in the phenotypic test. The majority of MDR-MRSA was belonged to agrI (67%, n = 24), followed by agr II (17%, n = 6), agrIV (11%, n = 4) and agrIII (5.5%, n = 2). The frequency of icaADBC genes were 75% (n = 27), 61% (n = 22), 72% (n = 26) and 72% (n = 26), respectively. Furthermore, the prevalence of clfA, clfB, fnbA, fnbB, fib, can, eno, ebps and bbp genes was 100%, 100%, 67%, 56%, 80%, 63%, 78%, 7% and 0%, respectively. Furthermore, approximately all the MRSA was strong biofilm producers. Conclusions: Multidrug-resistant isolates produced biofilm strongly and the majority harbored most of biofilm related genes, suggesting that biofilm formation is associated to the presence of these genes, and also biofilm production can increase the antibiotic resistance as have demonstrated in MDR-MRSA isolates.

Distribution of Genes Encoding Toxin, Adhesion, and Antibacterial Resistance Among Various SCCmec Types of Methicillin-Resistant Staphylococcus aureus Isolated From Intensive Care Unit, Tehran, Iran

“…As shown in Table 4, the most prevalent gene was clfA (187; 93.5%) followed by clfB (180; 90%), fnbA (163; 81.5%), fnbB (154; 77%), can (102; 51%), ebp (93; 46.5%), and bbp (5; 2.5%). This finding was in line with that of the study by Ghasemian et al (43) reporting high prevalence of clfA and clfB genes in their study. Similar to the studies previously reported (2,43), in the current study, the frequency of fnbA and fnbB genes were relatively high indicating the important role of these genes in colonization of MRSA.…”

“…This finding was in line with that of the study by Ghasemian et al (43) reporting high prevalence of clfA and clfB genes in their study. Similar to the studies previously reported (2,43), in the current study, the frequency of fnbA and fnbB genes were relatively high indicating the important role of these genes in colonization of MRSA. Results obtained in the current study showed that the frequencies of ebp (46.5%) and can (51%) encoding genes were different from those of Ghasemian et al (43) for can (78%) and ebp (7%) genes.…”

Distribution of Adhesion and Toxin Genes in Staphylococcus aureus Strains Recovered From Hospitalized Patients Admitted to the ICU

“…The transmission of this bacterium easily takes place via direct contact, such as touching contaminated hands (or other body parts) and droplet transmission, and via indirect contact, such as through the breathing of contaminated air in the hospital or other environments (2). The most significant factor that contributes to the successful and extensive distribution of this pathogen is the ability of S. aureus strains to express a variety of virulence factors and acquire resistance to new antimicrobial agents (3,4).…”

“…In recent decades, a wide pattern of resistance has been observed in S. aureus strains, not only to β-lactams but also to other therapeutic agents including macrolides, lincosides, and aminoglycosides (3,7). An important characteristic of S. aureus is its ability to acquire resistance to antimicrobial agents, especially methicillin, and methicillinresistant S. aureus (MRSA) has emerged as a major public health concern.…”

Prevalence of Multidrug Resistant Staphylococcus aureus and its Antimicrobial Susceptibility Pattern in a Tertiary Care Hospital in Navi Mumbai, India

“…In their study, 6.8% MSSA isolates were resistant to all other antibiotics tested. Abdolmajid et al, (2015) observed 30.6% MRSA prevalence in their study conducted in Tehran. Out of which 56.2% strains were MDRSA.…”