Molecular epidemiologic analysis of Staphylococcus aureus isolated from four burn centers

Jundishapur J Microbiol

et al. 2017

Background: Most methicillin-resistant Staphylococcus aureus (MRSA) infections occur in health care settings; therefore, it is important to know about antimicrobial susceptibility, and carriage of virulence genes in S. aureus isolates. Objectives: The current study aimed at determining the prevalence of genes coding antimicrobial resistance, toxins, and adhesion factors among various SCCmec types of MRSA isolated from intensive care units (ICUs). Methods: From April 2016 to March 2017, a total of 200 MRSA species were isolated from various clinical samples of patients hospitalized in ICUs. The Kirby-Bauer disk diffusion method was employed to determine resistance pattern. Conventional polymerase chain reaction (PCR) assay was utilized to demonstrate antimicrobial resistance, toxins, and adhesion genes. Different SCCmec types of MRSA strains were determine by the multiplex PCR assay. Results: Antibiotic susceptibility testing revealed that all the isolates were sensitive to linezolid, teicoplanin, and vancomycin. The frequency of high-level mupirocin-resistant MRSA was 5.5%. The presence of resistance genes ant(4')-Ia, aac(6')-Ie/aph(2"), tetM, msrA, ph(3')-IIIa, ermA, msrB, ermB, ermC, and mupA were detected 73.5%, 60.5%, 57.5%, 37%, 36.5%, 34.5%, 24%, 17%, 15% and 5.5%, respectively. The most prevalent adhesion genes were clfA (93.5%) followed by clfB (90%), fnbA (81.5%), fnbB (77%), can (51%), ebp (46.5%), and bbp (2.5%). The frequency of etb, eta, pvl, and tst genes were 4.5%, 9.5%, 21.5%, and 61.5%, respectively. Inducible macrolide-lincosamidestreptogramin B (inducible MLSB resistance; iMLSB), and constitutive MLSB (cMLSB) phenotypes were observed in 88 (44%) and 26 (13%) isolates. Different SCCmec types comprising type III (56.5%), type IV (25%), type II (11%) and type I (7.5%) were identified among the MRSA strains. Conclusions: Results of the current study showed a high prevalence of resistance to commonly used antibiotics that can be a serious threat to patients hospitalized in ICUs. Also, the current study findings showed that different SCCmec types causing nosocomial infections were associated with specific antimicrobial resistance, adhesion, and toxin gene profiles.

Section: Discussionsupporting

confidence: 93%

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

Abiri

Sepahi

Jundishapur J Microbiol

et al. 2017

“…The results of the current study showed that the most prevalent SCCmec type was type III (38.9%). This finding is in agreement with those reported from China (24) and Brazil (25), yet differs from that reported by Vazquez et al in Spain (26). The high frequency of SCCmec type III in the current study emphasizes the nosocomial origin of these strains in patients with UTIs.…”

Section: Discussionsupporting

confidence: 92%

SCCmec and spa Typing of Staphylococcus aureus Strains Isolated from Patients with Urinary Tract Infection: Emergence of spa Types t426 and t021 in Iran

Jundishapur J Microbiol

Abiri

Nasirian

et al. 2018

Background: Urinary tract infection (UTI) is one of the most frequent types of infections in community and hospital settings. Objectives: The aim of the present study was to investigate antimicrobial susceptibility patterns and also to determine spa and SCCmec types of Staphylococcus aureus strains isolated from patients with UTI. Methods: During a 12-month period, 863 urine samples were investigated. In vitro susceptibility of isolates was performed using the Kirby-Bauer disk diffusion method. Moreover, conventional PCR was performed to detect mecA, nucA, spa, and toxin (pvl, tst) genes as well as Multiplex PCR to determine SCCmec types. Results: A total of 90 isolates (10.4%) were analyzed in the present survey. Methicillin resistance was observed in 61.1% of the isolates. In total, 25 isolates (27.8%) were positive for the pvl-encoding gene and 40 (44.4%) for tst-1 encoding gene. Based on a multiplex PCR assay, the 4 different SCCmec types were detected as type III (38.9%), followed by type II (31.1%), type IV (28.9%), and type I (1.1%). PantonValentine Leukocidin (PVL) positive isolates belonged to SCCmec type IV (14.4%) and II (13.3%). The 90 S. aureus isolates were classified to 10 spa types t037 (23.3%), t924 (15.6%), t383 (15.6%), t426 (12.2%), t044 (12.2%), t790 (6.7%), t084 (4.4%), t021 (4.4%), t7580 (4.4%), and t064 (1.2%). The spa types t044, t790, and t084 were obtained from methicillin-resistant S. aureus (MRSA) strains and spa types t924 and t7580 from methicillin-sensitive S. aureus strains. Conclusions: To the best of the author's knowledge, this is the first study on spa types t426 and t021 in Iran. Since the majority of strains isolated from patients with UTI were MRSA, detection of MRSA clones and their characteristics is necessary.

“…The distribution of SCCmec types among MRSA isolates indicated that SCCmec type III was the prominent type (71.4%) in the current survey. This pattern is comparable to the distribution of SCCmec types among MRSA reported in China (37) and Brazil (30), but differs from that reported by Vazquez et al in Spain (38). This SCCmec type was previously reported as the most prevalent type in Iran by Japoni et al In the present study, the gene coding for pvl was found only among MRSA strains that harbored SCCmec type IV.…”

Section: Discussionsupporting

confidence: 81%

Distribution of SCCmec Types in Methicillin-Resistant Staphylococcus aureus Isolated from Burn Patients

Afshari

Sepahi

et al. 2017

Arch Clin Infect Dis

Background: Methicillin resistance Staphylococcus aureus (MRSA) isolates have been recognized as one of the most important causes of infection in burn patients that have recently shown a frequent and rapid development of antibiotic resistance. Objectives: The present study described the distribution of different SCCmec types and antibiotic resistance pattern among MRSA strains isolated from burn patients in a referral burn center in Tehran, Iran. Methods: During a 12-month study, 189 MRSA isolates were obtained from burn patients. Standard culture and biochemical tests were used for identification of MRSA isolates. The antibiotic susceptibility testing was performed using disc diffusion method and the presence of mecA, nucA, pvl, and tst encoding genes was determined using PCR method. In addition, the different SCCmec types were determined using multiplex PCR. Results: All the MRSA isolates were observed to be resistant to amoxicillin and penicillin and sensitive to linezolid, teicoplanin, and vancomycin. The rates of resistance to other antibiotics varied from 86.2% for amikacin to 17.5% for quinupristin-dalfopristin. MDR was observed in all the isolates. Six different antimicrobial resistance patterns were observed among our isolates. Based on the multiplex PCR assay, the two different SCCmec types were detected as 71.4% type III and 28.6% type IV. In total, 8.5% of isolates harbored pvl toxin encoding gene all of which belonging to SCCmec type IV. Furthermore, 33 isolates (17.5%) harbored tst encoding gene. Conclusions:The results showed low diversity of SCCmec type among circulating MRSA in the burn center with relatively high prevalence of SCCmec III. These findings support the need for more studies to elucidate distribution of different SCCmec types among MRSA isolated from burn patients.