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Prevalence of coagulase-negative staphylococci and determination of antimicrobial resistance in accompany with types of SCCmec in isolated of nosocomial infections
Mohammad Reza Arabestani , Mohammad Yousef Alikhani , Manoochehr Karami , Elham Salimi Ghale ,
Volume 73, Issue 12 (3-2016)
Abstract

Background: Coagulase-negative staphylococci (CoNS) were considered as contaminats previously, but, during the past decade considered as one of the most common photogenic bacteria in hospital. Resistance to beta-lactams especially methicillin in staphylococcus species is being worrying in hospitals. Rapid identification of mechanisms of resistance and confirmation of their resistance to methicillin is a basic principle for antibiotic treatment. The aim of this study was to determine antibiotic resistance, frequency of mecA gene, and determination of SCCmec types in CoNS isolates from teaching hospitals in Iran.

Methods: The descriptive cross-sectional study was carried out one hundred clinical samples isolated from patients with an average age of 7-69 years at teaching hospitals in Hamadan City, Iran, from September 2014 to February 2015. After confirmation of isolates by microbiological standard biochemical tests, antimicrobial susceptibility testing was performed by disk agar diffusion (DAD) method. After extraction of isolated genomicm, mecA gene was detected. Then, the types of SCCmec were performed by PCR.

Results: In this study, 387 clinical samples were collected which among 100 CoNS isolated, Staphylococcus epidermidis was the most prevalent species with frequency 55 (55%), followed by S. haemolyticus 40(40%) and S. saprophyticus 5(5%). The highest antibiotic susceptibility was to rifampin 96(96%) and the lowest resistance was detected for trimethoprim/sulfamethoxazole (TMP/SMX) 47(47%). None of the strains were resistant to vancomycin. Resistance to methicillin was detected in 50% of CoNS isolates. Typing of SCCmec was performed by The polymerase chain reaction (PCR). Frequency types of SCCmec was type III with frequency 13(13%), type V 11(11%), type II 6(6%), type IV 4 (4%), type I 3(3%) respectively. Thirteen isolated was not typable in this study.

Conclusion: The result of this study showed that a large percentage of coagulase-negative staphylococci are resistance to methicillin, and the prevalence of SCCmec type was type III, which encodes the largest number of resistance genes. This information could be use in epidemiological study for preventing of infectious control in hospital and health centers.


Investigating the antibiotic resistance pattern of MRSA isolates from blood and wound samples of patients admitted in a number of Tehran university of medical sciences hospitals: a brief report
Monireh Rahimkhani,, Zahra Rajabi,
Volume 80, Issue 7 (10-2022)
Abstract
Background: Considering the frequency of MRSA strains in hospitals and medical centers as well as in different communities, it seems necessary and important to observe the use of appropriate drugs in order to reduce antibiotic resistance and reduce the economic costs of treatment. This study aimed to investigate the antibiotic resistance pattern of MRSA isolated from blood and wound samples of patients. The study patients were hospitalized in different departments in a number of Tehran University of Medical Sciences hospitals.
Methods: In this descriptive cross-sectional study from September 2021 to February 2022, the blood and wound samples of the patients were collected and referred to laboratory. Staphylococcus aureus had identified by phenotypic and biotypic tests. MRSA isolates were screened by showing resistance to Cefoxitin by disc diffusion method and finally confirmed by examining the mecA gene by PCR. The microbial resistance pattern of MRSA was also measured by disk diffusion method and resistance to Vancomycin was confirmed by E.test.
Results: 41 isolates from 87 Staphylococcus aureus samples were confirmed as MRSA by present the mecA gene. The mecA gene was detected in all MRSA by PCR method. The antibiotic resistance pattern showed the highest sensitivity to Vancomycin and Linezolid with 100% sensitivity and the highest resistance to three antibiotics Erythromycin, Ceftriaxone and Cloxacillin with 97.57%by disk diffusion method. The most MRSA strains were isolated from the ICU department with 13 cases and the least MRSA strains were isolated from the two NICU and pediatric departments with one case.The majority of the population infected with MRSA belonged to the age group of 40-65 years.
Conclusion: The prevalence of microbial resistance with high dispersion was obtained among MRSA strains isolated from clinical samples; which indicates a significant increase in resistant strains and requires a quick and timely diagnosis to prescribe the appropriate antibiotic.

Survey of norA and mecA genes in methicillin–resistant Staphylococcus aureus strains isolated from wound and blood samples
Shokoufeh Akbari, Monireh Rahimkhani, Reza Mirnejad,
Volume 81, Issue 10 (1-2024)
Abstract
Background: Today, Methicillin-Resistant Staphylococcus Aureus (MRSA) has become one of the public health concerns due to its resistance to antimicrobial drugs, and this problem makes treating patients with infections caused by this bacterium difficult. Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) strains are pervasive in both community and hospital settings, primarily attributable to Staphylococcus aureus' capacity to colonize areas like the nose or skin. In this study, with the aim of comparing phenotypic (disc diffusion method) and genotypic (PCR) methods, to detect methicillin-resistant Staphylococcus aureus isolated from patients of hospitals under supervision of Tehran university of medical sciences, and also detection of nor A, that is the one of the most important genes in efflux pump cluster genes.
Methods: The present research was a cross- sectional study that was conducted from February 2022 to September 2023. In this research, 43 isolated strains of Staphylococcus aureus from wound discharge and blood samples, were collected from different departments of Tehran hospitals and had submitted to the research laboratory of the school of allied medical sciences in Tehran university of medical sciences. After identifying the strains, the resistance of the isolates to 14 types of antibiotics was checked by disk diffusion method.
Results: Staphylococcus aureus diagnostic tests including gram staining on colonies, catalase, coagulase, DNase tests were performed and it was found that all strains were Staphylococcus aureus. In the next step, all samples were resistant to Cloxacillin by disc diffusion method, and the presence of mec A gene in them was confirmed by PCR method, thus the presence of MRSA strains was confirmed from the genotypic point of view. Of the 43 Staphylococcus aureus strains, 26 samples were identified as having the nor A gene by PCR and electrophoresis.
Conclusion: The results of the present research have shown that the prevalence of Staphylococcus aureus bacteria in hospital samples is significant and resistance to methicillin and ciprofloxacin has increased in the strains of this bacteria.

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