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Background: Clindamycin inducible resistant Staphylococcus aureus (S.aureus) isolates can cause failure in treatment with this antibiotic. Biofilm production via polysaccharide intercellular adhesion (PIA) contributes in the colonization of S. aureus, resulting in the initiation of different diseases. The aim of this study was to detect icaADBC genes among isolates of S.aureus with inducible resistance to clindamycin. Materials and Methods: A total of 209 clinical S.aureus isolates werecollected and identified by conventional phenotypic tests. Isolates with inducible resistance to clindamycin were detected by double disk diffusion test (D-Test) using clindamycin (2 μg) and erythromycin (15 μg). Oxacillin was used to detect Methicillin resistant Staphylococcus aureus (MRSA) isolates. Polymerase Chain Reaction (PCR) was performed to detect the icaADBC genes. Results: The rate of clindamycin inducible resistance was 4% (n=8). All the isolates were susceptible to methicillin. Four isolates (50%) contained the whole icaADBC genes. The prevalence of icaA, icaB, icaC and icaD genes were 5 (62.5%), 4 (50%), 6 (75%) and 5 (62.5%), respectively. Conclusion: The results indicate that the prevalence of  icaADBC genes among clindamycin inducible resistant strains was low, and also these strains were susceptible to methicillin.

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Background: Staphylococcus aureus can cause infections with a wide spectrum of illnesses ranging from benign skin infections to bloodstream infection leading to mortality. Antimicrobial resistance especially methicillin resistance in S. aureus (MRSA strains) is currently problematic. The emergence of MRSA infections has developed in both the healthcare and the community settings.  The aim of this study was to determine the prevalence of MRSA and SCCmec types in Iran according to the previously published studies.    
Methods: For this review, the terms of MRSA, Iran, methicillin, mecA and SCCmec types were searched in searching engines including Google scholar, PubMed, SciVerse, and Scopus. Data from veterinary sources were excluded. Data were analyzed with Graph Pad Prism 6 considering meta-analysis section.
Results: Among several studies and approximately of 1810 results, the prevalence of MRSA was determined as approximately 56.5%. In the year of 2015 and 2016, results exhibited a higher prevalence of MRSA (62.2%) compared to 2013 and 2014, although not exceeded from 46% in healthy individuals. Moreover, among the SCCmec types, the SCCmec Type III has been reported as the predominant type (60.48%) followed by Type IV (21.2%), Type I (17.72%), Type II (17.12%), and Type V (0.56%). 
Conclusion: According to previous data, the prevalence of MRSA is increasing in Iran. However, it may be different for each year depending on several reasons. Moreover, the SCCmec Type III is the predominant type in the country. The SCCmec Type IV has also emerged in CA-MRSA isolates.

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A total of 200 samples of traditional ice creams were obtained randomly from the retail stores in the city of Shahr-e-kord. All the samples were analyzed for microbial contaminations according to the Iran national standard. Out of 200 samples, 100 showed mesophilic aerobic bacteria count more than 5*105 per gram of ice cream. One hundred fourteen samples showed Staphylococcus aureus count more than 102 per gram of ice cream. Ninety nine samples showed Enterobacteriacea count more than 102 per gram of ice cream. From 200 samples, 2 samples were Escherichia coli positive, and 24 samples showed Bacillus cereus count more than 103 per gram of ice cream. No Listeria monocytogenes was isolated from 200 samples.

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Aims: Many infectious diseases had traditionally been cured with herbal medicines. Antimicrobial agents are often produced synthetically to increase the food durability and quality. The purpose of this study was to determine the antimicrobial properties of the aqueous and alcoholic extracts of Allium schoenoprasum.
Materials & Methods: In this experimental study, after preparation Allium schoenoprasum samples, aqueous and alcoholic extracts were prepared and their minimum inhibitory concentration (MIC) was determined against Staphylococcus aureus, Bacillus cereus, Escherichia coli and Vibrio cholerae by micro broth dilution method. Erythromycin was used as the control.
Findings: The MIC of alcoholic and aqueous extracts of A. schoenoprasum was 16-256 and 32->256µg/ml, respectively and MBC of them were 32-256 and 64->256ug/ml, respectively. The A. schoenoprasum exhibited higher activity against S. aureus and B. cereus strains.
Conclusion: The extracts of A. schoenoprasum have antimicrobial effect on S. aureus, B. cereus, E. coli and V. cholerae strains in micro broth dilution method.

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Aims: Food safety has emerged as an important global issue with international trade and public health implications. Staphylococcus aureus is recognized as an important cause of food poisoning related to the consumption of raw, undercooked or mishandled foods worldwide. The aim of this study was to investigate the presence and the frequency of enterotoxin producing S. aureus and SE genes in meat samples collected from meat retail outlets and restaurants in Zanjan, Iran.
Materials and Methods: In this cross sectional study, from March to June 2015, a total of 90 individual meat samples were collected from meat retail outlets and restaurants in Zanjan, Iran and investigated the frequency of enterotoxin producing S. aureus and SE genes. The meat samples were immediately homogenized and cultured on Baird parker agar and subjected for confirmatory biochemical tests and molecular detection of femA, sea, seb, sec, sed and see genes.
Findings: A total of 31 (34.4%) meat samples were positive for the presence of S. aureus. The frequency of S. aureus in raw meat (23.3%) was higher than cooked meat samples (11.1%). Enterotoxin-producing capacity was determined in 18 (20.0%) out of 90 homogenized meat samples using ELISA technique. The most prevalent SE gene was sea (38.7%), followed by see (22.6%), sec (16.1%) and seb (12.9%). SE genes were not found in strains isolated from cooked meat samples.
Conclusion: Detection of enterotoxigenic S. aureus in raw meat samples shows a probable risk for public health.
 

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The effect of essential oil (EO) from Carum copticum at concentrations of 0 (control), 0.5%, 0.75% and 1% on Staphylococcus aureus growth and gene expression of enterotoxins (SE) A and C in surimi from kilka (Clupeonella cultriventris caspia) was determined during  0, 5, 10, 15 and 20 days of refrigeration storage (4 °C). The main compounds of EO were thymol (36.4%), p-cymene (31.4%) and γ-terpinen (21.73%). Minimum inhibitory concentration and maximum tolerable concentration of EO against in S. aureus in broth medium were 0.06% and 0.015%, respectively. The growth rate significantly differ between S.aureus population in control (11.31 log CFU/g) and EO-treated samples, 9.76, 7.21 and 6.06 log CFU/g in samples containing 0.5%, 0.75% and 1%, respectively. The highest inhibitory activity against gene transcription of entertoxins was observed at 1% EO; also, the inhibitory effect of EO concentrations against expression of enterotoxin C was higher than enterotoxin A., as enterotoxin A expression was 4.5 and 8.23 fold lower than control at days 5 and 20, and enterotoxin C expression, at days 5 and 20, decreased 5.11 and 8.94 fold compared to control. The results of this study showed that EO from C. copticum is an effective component in reducing bacterial growth rate and staphylococcal enterotoxins production in kilka surimi.  

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Aims: Methicillin-resistant Staphylococcus aureus (MRSA) is recognized as an important health problem worldwide. To counteract the human innate immunity, S. aureus produces a number of immune evasion cluster (IEC) including staphylokinase (SAK), staphylococcal enterotoxin P (SEP), staphylococcal enterotoxin A (SEA), staphylococcal complement inhibitor (SCIN), and chemotaxis inhibitory protein (CHIP) encoded by sak, sep, sea, scn, and chp genes, respectively. These genes are carried by β-hamolysin-converting bacteriophages. The present study was conducted to determine the IEC phage types and antibiotic resistance patterns in 145 clinical MRSA isolates from Khuzestan Province, Iran.
Methods: All the isolates were investigated by disc diffusion method and PCR assay of sak, sep, sea, scn, and chp genes.
Findings: The assessment of antibiotic resistance showed the highest rate of resistance towards penicillin (97.25%), followed by methicillin (95.8%), ceftazidime (81.4%), erythromycin (71.8%), clindamycin (61.4%), ciprofloxacin (60.7%), gentamycin (56%), imipenem (56.55%), and vancomycin (0%), respectively. Also, the frequency of IEC types was as follows: type A (4.8%), type B (9%), type C (13.1%), type D (12.4%), type E (27.6%), type F (1.4%), type G (0.7%), and type H (6.9%). On the other hand, 24.1% of the isolates did not show any of the IEC types.
Conclusion: The findings showed that IEC-carrying bacteriophages are highly prevalent among MRSA strains, resulting in the adaptation and counteraction of bacteria to the human immune system. Therefore, understanding the role of IEC in the virulence of bacteria can improve our knowledge about the evolution, vaccination, and treatment of S. aureus infection.

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Aims: Given the prevalence of methicillin-resistant Staphylococcus aureus infections and the importance of antibiogram pattern in the treatment of these infections, the present study aimed to evaluate the methicillin and vancomycin resistant Staphylococcus aureus clinical isolates.
Materials & Methods: S. aureus isolates were diagnosed using proprietary cultivation environments and standard biochemical methods by isolating 130 Staphylococcus samples from patients’ clinical specimens. The isolates antibiotic susceptibility pattern was determined by disc diffusion method. MRSA isolates were identified using cefoxitin discs, and the E-test method was used to determine the minimum inhibitory concentration (MIC) of vancomycin antibiotic. Furthermore, the multiplex PCR method was used to study the frequency of mecA and vanA genes.       
Results: In the present study, 57 out of 130 Staphylococcus isolates were diagnosed as S. aureus. According to the antibiogram test results, the isolates showed the highest resistance to penicillin (92.98%) and the lowest resistance to ciprofloxacin (10.52 %). In addition, the resistance to methicillin was reported as 21.56 % using cefoxitin disc.  According to the E-test results, 90% of the isolates were susceptible to vancomycin, and 10% showed heterogeneous resistance to vancomycin. The molecular analysis indicated that mecA gene was present in 35.08% of the isolates, but no isolate contained vanA gene.
Conclusion: Despite the lack of resistance to vancomycin, the isolates showed a high resistance to methicillin. Therefore, the present study results emphasized the necessity of performing antibiotic sensitivity tests before the drug administration. 

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Aim: The objective of this study was to determine the occurrence and antimicrobial resistance pattern of Staphylococcus aureus strains, as one of the important foodborne pathogens, isolated from unpacked ice creams.
Materials & Methods: A total of 122 unpacked ice cream samples were randomly collected from different localities in East Azerbaijan province and transferred to the laboratory using a cool box and screened for the presence of S. aureus strains. Also, the isolates resistance to antibiotics was determined by disk diffusion method.
Findings: In total, 21.3% of the ice creams samples were contaminated with S. aureus strains. Furthermore, antibiotic susceptibility testing revealed that the highest resistance was against penicillin and erythromycin, whereas the highest susceptibility was observed against gentamicin and rifampin. A warning issue was the significant resistance to vancomycin.
Conclusions: The relative high isolation and antimicrobial resistance rates detected in S. aureus strains isolated from unpacked ice creams underline the necessity for applying strict standards at all processing steps by food control agencies and emphasize the need for educational efforts for those personnel involved in products preparation procedures in order to promote food hygiene. It is worth noting that the emergence of resistance to vancomycin, as the last line of treatment for staphylococcal infections, is a worrying global health concern. Moreover, this study highlighted that poor adherence to personal hygiene and health principles during the food products preparation and/or storage could be a potential factor in the spread of pathogenic bacteria and resistance genes in the community.

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 Aims: Hospitalized patients are often immunocompromised as a result of invasive medical examinations and treatments. Of course, the tendency to do care practices for these patients and the hospital environment may facilitate the transmission of pathogenic microorganisms among them.
Materials & Methods: The study population and health status of volunteer patients were collected using a pretested questionnaire and patients information available in hospital files. A total of 102 samples were collected from patients’ wounds, noses, ears, and urine and microbiologically analyzed for the presence of Staphylococcus aureus species by plating on Manittol Salt agar. Colonies were purified by streaking on Nutrient agar, Gram stained, and tested for the presence of coagulase and the capability of growing on 3–5% salt concentration.
Findings: Male patients (51.3%) were more infected by S. aureus strains than female patients (48.7%). In terms of age, S. aureus infection rate was higher in patients within the age ranges from 17-50 years (56.32%) and lesser in patients within the age ranges from 51-100 years (43.68%). Genogram of the isolates indicated two major groups based on the genotypic responses to the antibiotics and extracts (This means the possible separation of the isolates into family groups according to their responses to antimicrobial agents). The prevalence of S. aureus colonization was higher in male patients.
Conclusions: Observed indices suggest that sex could be considered as a risk factor for S. aureus infection in patients. In addition to antibiotics, plants extracts could be used as an effective alternative for the treatment of S. aureus infections to control resistant S. aureus species.

 

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Aims: Staphylococcus aureus is a Gram-positive bacterium with the capability of causing a variety of nosocomial and community-acquired infections. Evaluating the genetic structure, polymorphism, genotyping, and phylogeny of S. aureus isolates could contribute to the prevention and treatment of infections caused by this microorganism.
Materials & Methods: In this study, the polymorphisms of 16S rRNA, rpoB, and hsp70 genes were investigated in a total of 50 S. aureus isolates using S. aureus NCTC 8325 as the reference strain. Polymerase chain reaction (PCR) was used for the detection and amplification of the studied genes. The amplicons were then sequenced using a Sanger sequencing method. Moreover, phylogeny of the isolates was studied using Neighbor-joining and Maximum Parsimony methods for 16S rRNA, rpoB, and hsp70 genes individually and in combination.
Findings: After Sanger sequencing, data obtained by Sequencher and Mesquite software programs revealed several polymorphisms of S. aureus isolates 16S rRNA, rpoB, and hsp70 genes, respectively. These polymorphisms included transversion, transition, insertion, and deletion. Among the studied strains, 10 cases showed no polymorphism. Multi-locus sequence analysis (MLSA) showed several genetic diversities in S. aureus isolates.
Conclusion: It seems essential to rapidly and reliably identify the phylogenetic sources and characteristics of this microorganism and to have a better understanding of its molecular epidemiology in order for infection practical surveillance and control.

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Aims: Following the emergence of methicillin-resistant Staphylococcus aureus (MRSA) isolates, the use of other antibiotics especially vancomycin in S. aureus infections has become inevitable, leading to the emergence of vancomycin-resistant S. aureus (VRSA) strains, which is considered as a major public health concern. This study aimed to determine the vancomycin susceptibility patterns of S. aureus clinical isolates in order to evaluate the current status of vancomycin resistance in the southwest of Iran.
Materials & Methods: In this study, 100 S. aureus clinical strains were collected from the hospitals of Khuzestan province in the southwest of Iran. Next, antibiotic susceptibility, vancomycin resistance, and the presence of mecA, vanA, vanB, vanC, and vanD genes were investigated in these isolates.
Findings:  It was found that 1 and 2 isolates were vancomycin-intermediate S. aureus (VISA) and VRSA, respectively. All three strains showed methicillin-resistance pattern and carried mecA gene. vanA gene was detected in VRSA strains, whereas vanB, vanC, and vanD genes were detected in none of these isolates.
Conclusion: This study findings could be alarming regarding the emergence and spread of VRSA strains; therefore, the principles of infection control should be employed in the healthcare systems to prevent the spread of VRSA strains in healthcare facilities.
 

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Aims: The aim of this study was to investigate chemical composition, antioxidant potential, and antimicrobial activity of cardamom essential oil against Staphylococcus aureus, Escherichia coli, and Saccharomyces cerevisiae species.
Materials & Methods: The chemical compositions of cardamom essential oil were identified by Gas Chromatography-Mass Spectrometry (GC-MS) device. Cardamom essential oil antioxidant activity was measured by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay, and its total phenolic compounds (TPC) were measured by Folin–Ciocalteu reagent. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of cardamom essential oil were determined using the serial-dilution method.
Findings: According to the GC-MS analysis results, 17 compounds were totally identified in cardamom essential oil, among which the most important compounds were 1, 8-cineole (36.74%) and α-terpinyl acetate (33.07%). MICs obtained for S. aureus, E. coli, and S. cerevisiae were 12.50, 25.00, and 1.56 mg/mL, respectively. Also, MBC obtained for both S. aureus and E. coli was 25 mg/mL, while MBC for S. cerevisiae was 3.36 mg/mL. Antioxidant activity measurement results showed that increasing the amount of cardamom essential oil reduced the amount of color and absorbance of DPPH solution to 517 nm. The results also showed that the amount of TPC in cardamom essential oil was 214.35 mg gallic acid per 100 g of dry material.
Conclusion: Cardamom essential oil used in this study showed antibacterial and anti-yeast activities against S. aureus, E. coli, and S. cerevisiae species. Antimicrobial effects of cardamom essential oil were predictable due to the presence of antimicrobial components in this oil.

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Introduction: Nanotecnology could solve most of problem of biomedical and cause improve in health and pharmacology field. Also this industrial cause to eliminate food pathogenic bacteria.increase of food pathogenic bacteria and resistance them to different antibiotics caused usage of nanotechnology by researchr and pharmacologiests. Material and Methods:In this reseach is studied antimicrobial effect of nanoparticles of silver,TiO2 against on food pathogenic bacteria such as Staphylococcus aureus PTCC 1431 and Listeria monocytogenes by determination MIC and MBC. Result: Silver nanoparticle was synthezied with 103 nm of size and consentraion of 1 mili molar,nano TiO2 with 21 nm of size and consentrain of 1% have antimicrobial effect against on Staphylococcus aureus PTCC 1431 Listeria monocytogenes . Conclusion: Since that antimicrobial activity of silver ,TiO2 nanoprticles against on food pathogenic bacteria (Staphylococcus aureus PTCC 1431 and Listeria monocytogenes) is proved, is suggested to packaging antimicrobial food. Keywords: Silver nanoparticle,TiO2,,Antimicrobial effect, Staphylococcus aureus PTCC 1431 Listeria monocytogenes

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Background: In recent years, the widespread prevalence of Multidrug-Resistant (MDR) Staphylococcus aureus strains and the increase in the number of Extensively Drug-Resistant (XDR) and Pandrug-Resistant (PDR) phenotypes amongst S. aureus strains have become one of the greatest challenges. This study aimed to determine the incidence of MDR, XDR, and PDR phenotypes in S. aureus strains in a teaching hospital in Gorgan, Golestan province, Iran.
Materials & Methods: Clinical samples of blood, urine, wound, and sputum were collected from all hospitalized patients during April to June 2019. S. aureus strains were identified using conventional biochemical methods, and antibiotic susceptibility assessment was performed by Kirby-Bauer disc diffusion method.
Findings: A total of 73 isolates were identified as S. aureus. The majority of S. aureus isolates were collected from wound specimens (31 out of 73). Most of the isolates were recovered from internal ward (35 out of 73), followed by intensive care unit (ICU) (16 out of 73). The highest susceptibility was observed to glycopeptides category (100%), and the lowest susceptibility was observed to erythromycin (54.7%), followed by cefoxitin (49.3%). Out of the 73 isolates, 32 (43.8%) were found to be methicillin-resistant S. aureus (MRSA) isolates. Among MRSA isolates, 96.8 and 12.5% were MDR and XDR, respectively. All of the MRSA isolates, were susceptible to vancomycin. No PDR phenotype was observed among the isolates as all of them were sensitive to vancomycin (100%).
Conclusion: Based on the obtained results, the highest and lowest antibiotic resistance was observed against erythromycin and vancomycin, respectively, which is consistent with similar studies conducted in the country. Therefore, these antibiotics should not be used in the empirical therapy of S. aureus infections

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Background: This study aimed to determine antibacterial activity of ethanolic extract of Matricaria chamomilla (chamomile) against methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant (MDR) Pseudomonas aeruginosa strains isolated from clinical specimens.
Materials & Methods: The plant samples were collected, and the flowers and leaves were separated and dried completely in the shade. After grinding, extraction was performed using the maceration method. The extracts of both flowers and leaves were dried at 37°C for 24 hrs. About 500 mg of the dried plant extract was dissolved in 10 mL of 5% dimethyl sulfoxide and sterilized by filtration through a 0.45 µm membrane filter. For the antibacterial assay, agar well diffusion and broth microdilution methods were used.
Findings: No inhibitory effect was observed for both extracts against MDR P. aeruginosa isolates in agar well diffusion method. In broth microdilution method, the leaves extract showed inhibitory effect, and its MIC and MBC were determined at 12.5 and 25 mg/mL concentrations, respectively. The flowers extract showed antibacterial activity against most MRSA isolates. The extract of leaves demonstrated inhibitory effect on 7 MRSA isolates. The MIC and MBC of flowers extract were determined at concentrations of 6.25 and 12.5 mg/mL for most MRSA isolates, while MIC and MBC of leaves extract were 12.5 and 25 mg/mL for a few MRSA isolates, respectively.
Conclusion: In this study, the ethanolic extract of chamomile leaves showed antibacterial activity against MDR P. aeruginosa isolates; meanwhile, the flowers extract showed better activity against MRSA isolates.

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Background: Mupirocin is a topical antibiotic inhibiting most Gram-positive cocci. Shortly after taking mupirocin, drug resistance emerges. This study aimed to determine mupirocin resistance in Staphylococcus aureus strains isolated from clinical specimens in Rasht.
Materials & Methods: In this study, a total of 85 clinical isolates of S. aureus were collected. Biofilm formation ability and antibacterial resistance patterns of isolates were investigated. Disc diffusion method and MIC determination were used to determine the susceptibility of strains to mupirocin antibiotic. Agr types, the presence of mupA, and mutation in ileS-1 were evaluated in mupirocin non-susceptible isolates by PCR and PCR sequencing, respectively.
Findings: Out of 85 tested strains, 57 (67%) isolates were recognized as biofilm producers, and all of which showed multidrug resistance phenotype. Agr type 1 was the most commonly detected type. Additionally, 12 mupirocin-resistant strains were identified in the disc diffusion and MIC tests. A total of four strains were mup-A positive and showed high-level resistance. In sequencing and mutation evaluation of the ileS-1 gene in eight low-level mupirocin-resistant strains, 12 types of silent mutation and one type of missense mutation were determined.
Conclusion: The study of mupirocin-resistant strains in this study showed the need to identify factors affecting the occurrence of resistance and to take control and prevention measures before mupirocin losses its efficacy.

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Backgrounds: Hospital sewage is known as an important source of human pathogenic bacteria such as methicillin resistant Staphylococcus aureus (MRSA) strains disseminated from hospital to the environment. This study aimed to investigate the presence of MRSA in the treated outgoing wastewater collected from a referral hospital in Tehran, Iran.
Materials & Methods: During 2015, sampling was carried out at two stages from a hospital wastewater. All black colonies with halos on HiCrome aureus agar medium supplemented with oxacillin were collected and identified as MRSA using specific primers for nucA and mecA genes. Isolates susceptibility to 18 antibiotics was determined according to the recommendations of the Clinical and Laboratory Standards Institute (CLSI). Bacterial typing was performed for the isolates using a combination of Phene plate (PhP) typing, prophage typing, staphylococcal cassette chromosome mec (SCCmec) and ccr typing methods.
Findings: A total of 79 MRSA isolates were confirmed using specific primers and showed susceptibility to quinupristin-dalfopristin, vancomycin, chloramphenicol, and linezolid. High resistance to penicillin, ciprofloxacin, kanamycin, tobramycin, and erythromycin was reported. Sixteen PhP types consisting of eight common types (CTs) and eight single types (STs) were identified among the strains, among which CT1 was the dominant type. Also, two prophage patterns and four prophage types were identified, and all the strains were positive for SCCmec type III and ccr type 3.
Conclusion: The results of this study revealed that sewage-treatment process was able to remove community-acquired MRSA (CA-MRSA) strains; however, hospital-acquired MRSA (HA-MRSA) strains were able to survive during the treatment process in this hospital.

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Backgrounds: Bacteriophage therapy could be an alternative strategy for the treatment of antibiotic-resistant bacteria. This study aimed to evaluate the antibacterial activities of isolated bacteriophages against methicillin-resistant Staphylococcus aureus (MRSA) isolates. 
Materials & Methods: A total of 16 clinical isolates of MRSA were collected from medical diagnostic laboratories in Tehran, Iran. A specific bacteriophage was isolated from hospital sewage using double-layer agar. Phage morphology was evaluated by transmission electron microscopy (TEM). Different bacteria were selected to determine the bacteriophage host range using spot test. Phage susceptibility to temperature and pH was evaluated by double-layer agar method.  In vitro assay was carried out on human epithelial type 2 (HEp-2) cells to investigate the effect of bacteriophage on the adhesion of MRSA to human epithelial cells. 
Findings: TEM suggested the Myoviridae family for the isolated phage. The effective titer of bacteriophages was 1.8×10⁷ PFU/mL. The isolated bacteriophage was stable at 4 ˚C and pH=8. The isolated bacteriophage was specific for all clinical isolates of MRSA and had no lytic activity against other pathogenic bacteria. In evaluating the binding and invasion of MRSA to the HEp-2 cell line, as expected, the lytic activity of specific bacteriophages was observed following inoculation.
Conclusion: The specificity and lytic activity of this phage on MRSA and MRSA-infected HEp-2 cell line emphasized that the isolated bacteriophage may serve as an effective prophylactic and alternative therapeutic agent in hospital settings.

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Backgrounds: Staphylococcus aureus is one of the major causes of nosocomial infections. Biofilm formation is an important virulence factor of S. aureus, leading to its high resistance to antibiotics and evasion from host defenses. This study aimed to assess the prevalence and antimicrobial resistance profile of biofilm-producing S. aureus strains and characterize genes involved in biofilm formation.
Materials & Methods: A total of 79 S. aureus strains were isolated from 1000 clinical samples and characterized using phenotypic, biochemical, and molecular tests. The biofilm production ability of isolates was examined using the microtiter assay. Moreover, the expression of genes involved in biofilm production (psm A and psm B) was screened using real-time PCR. Finally, antibiotic susceptibility testing was done using the Kirby-Bauer method and interpreted according to the CLSI M100 standard.
Findings: Out of 79 S. aureus isolates, 43 (54.4%) isolates were strong biofilm producers, 21 (26.6%) isolates were weak biofilm producers, and 15 (19%) isolates were non-adhesive. The results of real-time PCR showed that 55 (86%), 60 (93.7%), and 46 (58.2%) isolates were positive for psm A, psm B, and both genes, respectively. The results of antibiotic susceptibility testing showed that all the isolates were resistant to two or more antibiotics.
Conclusion: The high prevalence of biofilm-forming S. aureus strains in hospital environments could be a major health challenge with serious outcomes for hospitalized patients. Thus, it is necessary to disinfect hospital environments to reduce the risk of infection and spread of these microorganisms.