Molecular Characterization of Methicillin Resistant Staphylococcus aureus Strains Isolated from Intensive Care Units in Iran: ST22-SCCmec IV/t790 Emerges as the Major Clone (original) (raw)
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Journal of Clinical Immunology and Microbiology, 2022
Results: Out of 430 clinical samples, 117 (27.20%) Staphylococcus aureus were isolated of which 42 (35.89%) were identified as MRSA. The most MRSA obtained from the ICU department with 25 cases (59.52%). The majority of patients infected with MRSA belonged to the age group of 40-65 years. The mecA gene was detected in all MRSA. The entire MRSA was 100% sensitive to vancomycin and linezolid, and 100% resistance to cloxacillin. Molecular detection of vanA gene in isolated MRSA showed 2 (4.76%) of them contained vanA gene. Conclusion: The high prevalence of MRSA and its antibiotic resistance pattern to vancomycin and other antibiotic families can lead to treatment failures, uncontrolled nosocomial infections, and mortality. Although the PCR-based detection method is superior to other conventional techniques, a combination of these methods can provide diagnostic accuracy.
Nepal Medical College Journal
Resistance shown by Staphylococcus aureus to methicillin; mediated by mecA, and vancomycin; mediated by vanA, has led to difficulty in treatment of related infections. Despite reports showing methicillin resistant S. aureus (MRSA) and vancomycin resistant S. aureus (VRSA) in Nepal, and need for their regular surveillance, no study has been conducted on it in our hospital. So, this study is aimed to determine prevalence of MRSA, VRSA and their molecular characterization along with antibiogram. A descriptive cross-sectional study was conducted from August to December, 2022 in Clinical Microbiology Laboratory of NMCTH among S. aureus (n=160) isolated from various clinical specimens after receiving ethical approval from NMC-IRC. AST was done by modified Kirby-Bauer’s disc diffusion method. MRSA and VRSA were detected by cefoxitin disc method and agar dilution method respectively. Inducible clindamycin resistance was detected by D-test. Resistant genes (mecA, PVL, and vanA) were detected...
Background and Objective: Staphylococcus aureus is one of the important factors causing nosocomial infections. The emergence of antibiotic-resistant Staphylococcus strains to Methicillin and other antibiotics has brought about several problems in treatment of the infections caused by Staphylococcus strains. The aim of this study is to identify antibiotic resistance patterns of Methicillin-resistant Staphylococcus aureus isolates from patients in selected hospitals in Isfahan. Materials and Methods: In this descriptive cross-sectional study, a total of 300 samples were isolated from hospital patients in Isfahan. Clinical strains were investigated phonotypical characterization like Gram stain, catalase, coagulase and carbohydrate fermentation to identify SA, then disk diffusion test was performed on SA based on CLSI to isolate MRSA, in addition antibiotic sensibility pattern obtained using Oxacillin, Tetracycline, Clindamycin, Rifampin, Ampicillin, Ciprofloxacin, Gentamicin, Cotrimoxazole, Vancomycin. The PCR was performed for the detection of the mecA gene in all the MRSA isolates. Results: In this study, 210 (70%) samples in a total of 300 isolates of Staphylococcus aureus were Methicillin-resistant. Evaluation and assessment of antibiotic resistance in MRSA isolates showed the greatest resistance to Oxacillin (100%), Tetracycline (97%), Clindamycin (92%), Rifampin (75%), Ampicillin (70%), respectively, while the lowest levels of resistance were observed to antibiotics Ciprofloxacin (61%), Gentamicin (50%), Cotrimoxazole (34%), and Vancomycin (0%), respectively. The implication of this high resistance is that Methicillin-resistant Staphylococcus aureus infections should be treated with more precaution and not with Penicillin and other ineffective antibiotics. The presence of mecA gene in all isolates was confirmed by PCR. Conclusion: In this study, the spectrum of antibiotic resistance in MRSA isolates is similar to other studies. The Effectiveness of Tetracycline, Rifampin and Clindamycin is still very low on MRSA samples.
2004
Background: The global spread of methicillin-resistant Staphylococcus aureus (MRSA) infections necessitates the use of validated methods for the identification and typing of this bacterium. This study aimed to determine the distribution of main molecular types of MRSA strain circulating among hospitalized patients in teaching hospitals in Isfahan and Kashan. Methods: A total of 146 Staphylococcus aureus strains were isolated from patients in four teaching hospitals in Isfahan and Kashan during June 2017 to September 2018. The antimicrobial resistance patterns of Staphylococcus aureus strains were performed by disc diffusion method. The MRSA strains were identified phenotypically and confirmed by PCR assay. The prevalence of microbial surface components recognizing adhesive matrix molecules (MSCRAMMs) genes among MRSA strains was evaluated by multiplex PCR. The genotypes of MRSA strains were determined by multilocus sequence typing and SCCmec typing. Results: Of 146 Staphylococcus aureus isolates, 24 (16.4%) isolates were identified as MRSA strains. According to antimicrobial susceptibility testing the highest resistance rates were seen for tetracycline, erythromycin, ciprofloxacin and gentamicin. All of Staphylococcus aureus isolates were susceptible to vancomycin whereas 3 (2.1%) isolates were resistant to linezolid. Three different SCCmec types were obtained among MRSA strains including 16 (66.7%) SCCmec type V, 3 (12.5%) SCCmec type III and 5 (20.8%) SCCmec type II. Of 24 MRSA isolates 20 (83.3%) carried MSCRAMMs genes including eno (70.8%), fib (54.1%), cna (25.0%), fnbB (16.6%), ebps 5 (20.8%), and the fnbA, bbp and clfA genes were not detected in any MRSA isolate. MLST analysis revealed 11 sequence types among MRSA isolates as follows:
Chemotherapy, 2021
Background: Emergence and prevalence of Methicillin-Resistant Staphylococcus aureus (MRSA) has become a major universal health concern, limiting therapeutic options. Methods: In the North side of Iran, during the years 2015 to 2017, a total number of 37 MRSA isolates, including 19 clinical isolates from hospitalized patients and 18 colonizing isolates from health care workers were identi ed from three hospitals, in Gorgan, North of Iran. Antimicrobial susceptibility test was performed using the disk diffusion method and E-test. The presence of virulence and antibiotic resistance determinants were evaluated by PCR. The genotypic characterization was further analyzed using multi-locus sequence, spa, SCCmec, and agr typing. Results: The frequency of MRSA among S. aureus isolates was 38.14% (37/97). The most frequent S. aureus resistant isolates were found to be obstinate against penicillin (98%) and gentamicin (82.5%). Additionally, the lowest resistance rates were found against daptomycin (0%), vancomycin (2.7%), and quinupristin-dalfopristin (5.4%). All MRSA isolates were susceptible to daptomycin with MIC 50 /MIC 90 of 0.25/0.5 µg/ml. One isolate belonging to the ST239-SCCmecIII/t037 clone (MIC≥16μg/ml) was resistant to vancomycin. All but one isolate that shares the ST22-SCCmec IV/t790 strain were positive for both tsst and pvl genes. The most predominant MRSA isolates (27%) were associated with the ST239-SCCmec III/t037 clone; and followed by ST239-SCCmec III/t924 (16.2%). Conclusions: In our study, circulating MRSA strains were genetically diverse with a high prevalence of the ST239-SCCmecIII/t037 clone. These ndings emphasize the need for future and continuous surveillance studies on MRSA to prevent the dissemination of multidrug resistance and existing MRSA clones in an effective manner. [2, 13]. The geographical differences in the genotypic characteristic of MRSA have been reported [2]. In Asia, there is signi cant divergence among countries and regions with respect to prevalence of MRSA; in fact, ST22-SCCmec IV/t790 and ST239-SCCmec III/t037 clones are predominant among patients in Iran [2, 14], and so is ST239-spa t037 and ST5-spa t002 in China [15]. On the other hand, in many regions in Asia [16, 17], sequence type 239 (ST239) is most prevalent, where, in UK, ST36 and ST30 are the most common types [18]. With this background, we are evaluating the molecular characteristics, antibiotic resistance patterns, and virulence genes pro les of MRSA isolates obtained from two kinds of study populations, namely hospitalized patients and health care workers (HCWs) in Gorgan, North of Iran. Methods Study Design and Sample Collection of S. aureus Isolates This cross-sectional study was conducted from January 2, 2016 to October 28, 2018 in three hospitals (total of 920-beds) in Gorgan, North of Iran. Written informed consent was obtained from all the patients or HCWs and the study protocol was approved by the Ethics Committee in Golestan University of Medical Sciences (No. 31078693122419), and was conducted in accordance with the Declaration of Helsinki. The demographic pro les of patients and HCWs were recorded. We identi ed S. aureus and MRSA in hospitalized patients and HCWs as well (Table 1). Only the rst sample of each patient was included in the study. In case of HCWs, samples were collected from both anterior nares. 302 unduplicated clinical samples (blood, urine, wound, sputum, and others) were obtained from in-patients, out of which S. aureus and MRSA were identi ed in 53 (17.5%), and 19 specimens (6.29%), respectively. Likewise, 351 unduplicated non-clinical samplings from the anterior nares of HCWs were carried out. All the samples were sent for bacterial culturing and identi cation, using Gram staining, and standard biochemical tests, such as catalase, tube coagulase, DNase test, and mannitol fermentation [19]. The identi cation process of all S. aureus isolates was con rmed by using genotypic methods for the presence of nucA, and femA genes [2, 20]. Data on department and period of hospitalization, clinical symptoms, antibiotic usages, and underlying conditions were recorded.
Chemotherapy
Objectives: Emergence and prevalence of methicillin-resistant Staphylococcus aureus (MRSA) have become a major universal health concern, limiting therapeutic options. Methods: A total number of 37 MRSA isolates, including 19 clinical isolates from hospitalized patients and 18 colonizing isolates from health care workers were identified from 3 hospitals, in Gorgan, North of Iran. Antimicrobial susceptibility test was performed using the disk diffusion method and E-test. The presence of virulence and antibiotic resistance determinants were evaluated by PCR. The genotypical characterization was further analyzed using multi-locus sequence, spa, staphylococcal cassette chromosome, mec (SCCmec), and agr typing. Results: The frequency of MRSA among S. aureus isolates was 38.14% (37/97). The most frequent S. aureus resistant isolates were found to be obstinate against penicillin (98%) and gentamicin (82.5%). Additionally, the lowest resistance rates were found against daptomycin (0%), vanco...
Antimicrobial Resistance and Infection Control, 2020
Background: The global spread of methicillin-resistant Staphylococcus aureus (MRSA) infections necessitates the use of validated methods for the identification and typing of this bacterium. This study aimed to determine the distribution of main molecular types of MRSA strain circulating among hospitalized patients in teaching hospitals in Isfahan and Kashan. Methods: A total of 146 Staphylococcus aureus strains were isolated from patients in four teaching hospitals in Isfahan and Kashan during June 2017 to September 2018. The antimicrobial resistance patterns of Staphylococcus aureus strains were performed by disc diffusion method. The MRSA strains were identified phenotypically and confirmed by PCR assay. The prevalence of microbial surface components recognizing adhesive matrix molecules (MSCRAMMs) genes among MRSA strains was evaluated by multiplex PCR. The genotypes of MRSA strains were determined by multilocus sequence typing and SCCmec typing. Results: Of 146 Staphylococcus aureus isolates, 24 (16.4%) isolates were identified as MRSA strains. According to antimicrobial susceptibility testing the highest resistance rates were seen for tetracycline, erythromycin, ciprofloxacin and gentamicin. All of Staphylococcus aureus isolates were susceptible to vancomycin whereas 3 (2.1%) isolates were resistant to linezolid. Three different SCCmec types were obtained among MRSA strains including 16 (66.7%) SCCmec type V, 3 (12.5%) SCCmec type III and 5 (20.8%) SCCmec type II. Of 24 MRSA isolates 20 (83.3%) carried MSCRAMMs genes including eno (70.8%), fib (54.1%), cna (25.0%), fnbB (16.6%), ebps 5 (20.8%), and the fnbA, bbp and clfA genes were not detected in any MRSA isolate. MLST analysis revealed 11 sequence types among MRSA isolates as follows:
Infection and Drug Resistance
The main objective of this study was to decipher the prevalence, antimicrobial resistance, major virulence genes and the molecular characteristics of methicillin-resistant Staphylococcus aureus (MRSA) isolated from different clinical sources in southern China. Materials and methods: The present study was performed on 187 non-duplicate S. aureus clinical isolates collected from three tertiary hospitals in Guangdong Province, China, 2010-2016. Antimicrobial susceptibility testing was performed by the disk diffusion method and by measuring the minimum inhibitory concentration. Screening for resistance and virulence genes was performed. Clonal relatedness was determined using various molecular typing methods such as multilocus sequence typing, spa and staphylococcal chromosomal cassette mec (SCCmec) typing. Whole genome sequencing was performed for three selected isolates. Results: Out of 187 isolates, 103 (55%) were identified as MRSA. The highest prevalence rate was found among the skin and soft tissue infection (SSTI) samples (58/103), followed by sputum samples (25/103), blood stream infection samples (15/103) and others (5/103). Antimicrobial susceptibility results revealed high resistance rates for erythromycin (64.1%), clindamycin (48.5%), gentamicin (36.9%) and ciprofloxacin (33.98%). All isolates were susceptible to vancomycin. Resistance genes and mutation detected were as follows: aac(6')aph(2") (24.3%), dfrG (10.7%), rpoB (21.4%), cfr (0%), fexA (1.94%), gyrA (35.92%), gyrB (0.97%), grlA (20.4%), grlB (10.68%), ermA (21.4%), ermB (18.44%), ermC (21.4%) and lnuA (18.44%). Profiling of virulence genes revealed the following: sea (11.7%), seb (21.4%), sec (0.97%), sed (0.97%), hla (86.41%), hlb (17.48%), hlg (10.68%), hld (53.4%), Tsst-1 (3.9%) and pvl (27.2%). Clonal relatedness showed that ST239-SCCmecA III-t37 clone was the most prevalent clone. Conclusion: Our study elucidated the prevalence, antibiotic resistance, pathogenicity and molecular characteristics of MRSA isolated from various clinical sources in Guangdong, China. We found that the infectious rate of MRSA was higher among SSTI than other sources. The most predominant genotype was ST239-SCCmecA III-t37 clone, indicating that ST239-t30 clone which was previously predominant had been replaced by a new clone.
Archives of Pediatric Infectious Diseases, 2017
Background: Methicillin resistant Staphylococcus aureus (MRSA) are one of the most common and important pathogens, accounting for diverse nosocomial and community-acquired infections. The serious concern about these bacteria is the development of antibiotic resistance. Objectives: The present study was conducted to investigate the frequency of MRSA strains, their epidemiological and molecular relationships and antibiotic susceptibility patterns of isolated strains from university teaching hospitals of Tabriz, Northwestern Iran (during years 2014 and 2015). Methods: A total of 215 non-repetitive clinical isolates of S. aureus were identified using standard methods. The MRSA isolates were detected by the combination of phenotypic and genotypic methods. The presence of pvl gene and SCCmec types was determined by PCR and multiplex PCR, respectively. The MRSA isolates, in which the presence of mecA gene had been confirmed by PCR, were subjected to Rep-PCR analysis. Resistance to antibacterial agents was determined by disk diffusion, screening agar, and E-test methods. Results: All S. aureus isolates were positive for nuc gene and 87 (40.5%) of them revealed the presence of mecA gene, confirming them as MRSA. All isolates were found to be sensitive to linezolid and vancomycin. However, a reduced sensitivity of 3 MRSA isolates to vancomycin was observed (MIC = 6 µg/mL). SCCmec type III was the most prevalent (79.31%), followed by type IVd (13.80%) and type I (6.90%). The PVL occurrence was detected in 33 (15.35%) S. aureus isolates. The MRSA isolates could be divided to 2 main clusters, indicating the possible clonal relatedness of MRSA isolates. Conclusions: The MRSA isolates with SCCmec type III were the predominant MRSA strains in this area. The majority of MRSA isolates were MDR. Linezolid and vancomycin were found as suitable antibiotics for the treatment of MRSA. The results of typing methods indicated possible clonal relatedness among MRSA isolates. Therefore, routine infection control surveillance is necessary for the prevention of epidemic emergence.
2020
Background: The global spread of methicillin-resistant Staphylococcus aureus (MRSA) infections necessitates the use of validated methods for the identification and typing of this bacterium. This study aimed to determine the distribution of main molecular types of MRSA strain circulating among hospitalized patients in teaching hospitals in Isfahan and Kashan. Methods: A total of 146 Staphylococcus aureus strains were isolated from patients in four teaching hospitals in Isfahan and Kashan during June 2017 to September 2018. The antibiotic resistance patterns of Staphylococcus aureus strains were performed by disc diffusion method. The MRSA strains were identified phenotypically and confirmed by PCR assay. The prevalence of microbial surface components recognizing adhesive matrix molecules (MSCRAMMs) genes among MRSA strains was evaluated by multiplex PCR. The genotypes of MRSA strains were determined by multi-locus sequence type and SCC mec typing. Results: Of 146 Staphylococcus aureus isolates 24 (16.4%) isolates identified as MRSA strains. According to antibiotic susceptibility testing the highest resistance rates were seen to erythromycin, cefoxitin and clindamycin. All of Staphylococcus aureus isolates were sensitive to vancomycin whereas 3 (2.1%) isolates were resistant to linezolid. Three different SCC mec types were obtained among MRSA strains including 16 (66.7%) SCC mec type V, 3 (12.5%) SCC mec type III and 5 (20.8%) SCC mec type II. Of 24 MRSA isolates 20 (83.3%) carried MSCRAMMs genes including eno (70.8%), fib (54.1%) , cna (25.0%), fnbB (16.6%) , ebps 5 (20.8%), and fnbA , bbp and clfA genes were not detected. MLST analysis revealed 11 sequence types among MRSA isolates as follows: