Molecular characterization of the first community-acquired methicillin-resistant Staphylococcus aureus strains from Central Iran

Seyedjavadi

Azad

et al. 2016

Arch Clin Infect Dis

Background: Nosocomial Staphylococcus aureus is known as an important clinical pathogen in health care, hospital, and community settings. One of the serious threats associated with clinical isolates of Staphylococcus aureus is multi-drug resistance associated with integrons. Objectives: The objective of the present study was to investigate antimicrobial susceptibility patterns, frequency of class 1 and 2 integrons, and associated gene cassettes in different spa types of Staphylococcus aureus isolated from intensive care units (ICUs). Methods: During a five-month descriptive cross-sectional study, 80 Staphylococcus aureus strains isolated from hospitalized patients in ICU wards in five hospitals of Tehran, Iran were investigated. Staphylococcus aureus isolates were submitted to susceptibility testing and Polymerase Chain Reaction (PCR) to detect mecA gene, class 1 and 2 integrons, and associated gene cassettes. All the isolates were genotyped by staphylococcal protein A (spa) typing. Results: The overall prevalence of Methicillin-resistant Staphylococcus aureus (MRSA) was found to be 86.2%. All the isolates were susceptible to vancomycin, teicoplanin and linezolid and resistant to penicillin and ampicillin. All the 80 Staphylococcus aureus isolates were observed to be multi-drug resistant. Class 1 and 2 integrons were commonly found in 56.3% and 18.7% of the isolates, respectively. Six different gene cassettes were detected in class 1 integron (aadA2, aadB, blaoxa, aacA4, cmlA6, and catB) and three were found in class 2 (dfrA1, aadA1, and sat2). Gene cassette arrays aadA, aadB, blaoxa, and aacA were common in the two integron classes of Staphylococcus aureus isolates. Five different spa types of t790, t030, t969, t7580 and t1425 were identified among our isolates where spa type t790 was the most predominant spa type among integron-bearing Staphylococcus aureus strains. Conclusions: The present study reports on a high rate of multi-drug resistance, the predominance of the frequency of class 1 integron, and the emergence of spa type t790 among Iranian Staphylococcus aureus strains. The results revealed that the dissemination of multi-drug resistance among Staphylococcus aureus isolates may be associated with the presence of integrons. Therefore, continuous surveillance to monitor integrons and the associated gene cassettes among nosocomial pathogens, especially Staphylococcus aureus, is essential.

Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Distribution of spa Types, Integrons and Associated Gene Cassettes in Staphylococcus aureus Strains Isolated From Intensive Care Units of Hospitals in Tehran, Iran

Seyedjavadi

Azad

et al. 2016

Arch Clin Infect Dis

“…Our analysis of 106 MRSA clinical isolates using spa typing revealed 6 different spa types with t030 detected in 66% of the isolates as the most prevalent spa type. Spa type t030 was previously reported in another conducted study done by Japoni-Nejad et al (28) from Iran and is in agreement with findings of Chen et al (29) who suggested that strains with t030 was successfully established as the dominant spa type in hospitals in China. In contrast to other reports from Iran (14), Saudi Arabia (30), and Malaysia (31), our data demonstrated low frequency of t037 (14.2%) with variability in resistances pattern, among MRSA isolated from burn-injury patients.…”

Section: Discussionsupporting

confidence: 90%

“…Other spa types identified with low frequency in this study included t1358 (4.7%), t937 (3.8%), and t084 (1.9%). The distribution of these spa types was in agreement with results of the previous surveys in Iran (28,32). Although t937 was reported more in clinical S. aureus strains, there is evidence that it can be observed in methicillin sensitive S. aureus (MSSA) and as well as in strains recovered from animals (34).…”

Section: Discussionsupporting

confidence: 89%

Molecular Characterization and Distribution of Class 1 Integron-Bearing Methicillin Resistant Staphylococcus aureus Strains in Burn Patients, Tehran, Iran

Jundishapur J Microbiol

Seyedjavadi

Udo

et al. 2016

Background: Methicillin resistant Staphylococcus aureus (MRSA) is an increasingly common hospital pathogen in burn patients, which is known to cause over 50% of burn related deaths. One of the serious threats associated with clinical isolates of MRSA is multi-drug resistance, which is associated with integrons. Objectives: The aim of this study was to determine the distribution and molecular types of MRSA in burn patients and their carriage of integrons. Methods: During a 7-month period, 106 MRSA isolates were collected from burn wounds of patients admitted to a referral burn hospital in Tehran. Antimicrobial susceptibility testing (AST) was performed for 12 antimicrobial agents. Polymerase chain reaction (PCR) was used to detect nucA, mecA, pvl and tsst-1 genes, and class 1 and 2 integrons. Multiplex PCR technique was used to determine the Staphylococcal cassette chromosome mec (SCCmec) types of MRSA strains. All isolates were genotyped by staphylococcal protein A (spa) typing. Results: AST showed the lowest rate of resistance to quinupristin-dalfopristin (19.8%), mupirocin (31.3%), and rifampicin (37.7%). All isolates were susceptible to vancomycin, teicoplanin, and linezolid. Multi-drug resistance was observed in 97% of isolates. The most SCCmec type was SCCmec type III (98.1%) while only 2 (1.9%) MRSA isolates harbored SCCmec type IV. SCCmec types I, II, and V were not detected. The study revealed the presence of class 1 integron in 58 (54.7%) isolates and class 2 integron in 3.8% of isolates. Six different spa types of t030 (66%), t037 (14.2%), t065 (9.4%), t1358 (4.7%), t937 (3.8%), and t084 (1.9%) were identified amongst the isolates. Conclusions: The study revealed a high prevalence of multi-drug resistance (MDR), class 1 integron, SCCmec type III, and spa type t030 amongst MRSA associated with burn wounds in an Iranian hospital. The existence of SCCmec type III in burn patients emphasizes the nosocomial origin of these strains.

“…Although vancomycin-resistant S. aureus isolates are reported in many parts of the world, the results of susceptibility testing revealed that all isolates were susceptible to vancomycin and inhibited at ≤ 2 µg/mL consistent with other studies in Iran (25) and those of other countries (19,26), which reported that MRSA was almost always susceptible to the mentioned antibiotics. This could be explained by the successful implementation of infection control programs and appropriate use of antibiotics in clinics.…”

Section: Discussionsupporting

confidence: 87%

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

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.