Abstract  Background: Methicillin-resistant Staphylococcus aureus (MRSA) has been recognized as a matter of antibiotic resistance that is largely developed amongst common foodborne pathogens. MRSA is being considered as an important worldwide health threat and causes considerable concern to clinicians, food products manufacturers, governments and also consumers. OBJECTIVES: The objective of this study was to detect MRSA isolated from 360 samples of pastry cream products sold in the local markets in Amol, June 2016- May 2017, by plate count method and molecular technique. METHODS: The conventional plate counting method was conducted through inoculating appropriate dilutions of samples onto the Baired Parker Agar plates. MRSA isolates were detected by PCR method using mecA primers set. The resistance of isolated MRSA strains against some antibiotics was determined. RESULTS: Out of 360  pastry cream samples tested, 41.6% (150 samples) were contaminated by S. aureus with an average count of 4.94 log CFU/g in summer; 4.72 log CFU/g in autumn, 2.74 log CFU/g in winter and 3.62 log CFU/g in spring. Eleven samples out of 360 tested (3.05%) showed positive results for the mecA gene. No MRSA isolate was identified amongst winter samples. 56% of isolated strains showed sensitivity to oxacillin, 7% of isolates were sensitive to penicillin, 23 to ampicillin, 82% to gentamicin and 33% to tetracycline. CONCLUSIONS: According to the results, monitoring and improving the hygienic conditions of food production chain and educating food handlers and staff involved in food preparation is recommended in order to prevent MRSA prevalence.

BACKGROUND: Staphylococcal foodborne intoxication is the most common cause of foodborne illnesses by Staphylococcus aureus strains and most are caused by the enterotoxins of S. aureus. Staphylococcal enterotoxin A (SEA) is the most frequently responsible for staphylococcal food poisoning outbreaks. From a food safety and human health point of view, lactic acid bacteria (LAB) may provide a promising strategy in the fight against S. aureus.OBJECTIVES: Increasing product shelf life, and enhancing the safety of food and human health using natural microflora are the aims of this study. METHODS: In this study we evaluate the inhibitory effects of three lactobacillus strains isolated from yoghurt, namely lactobacillus acidophilus, lactobacillus fermentum and lactobacillus paracasei, on the growth and enterotoxin production of Staphylococcus aureus by co-incubating each strain with enterotoxigenic S. aureus at two temperatures: 25 and 35°C. Expression of the SEA gene of S. aureus was assessed by real-time PCR. RESULTS: All the strains decreased the bacterial count at both temperatures compared to the control. This effect was greater at 25°°C than at 35°C. The production of SEA, SEC and SEE was inhibited by all the isolates tested. Furthermore, expression of the sea gene was significantly suppressed in S. aureus co-cultured with the lactobacillus isolates and the greatest impact was on Lactobacillus acidophilus at 35 ° C. CONCLUSINS: This research highlights the potential of lactic acid bacteria isolated from traditional foods for use as natural preservatives in foodstuffs and suggests a new approach for biocontrol of Staphylococcus aureus.

BACKGROUND: Bacterial resistance to antibiotics is a crucial public health problem. Essential oils (EOs) possess antimicrobial effects and have been screened as potential natural antimicrobial compounds. OBJECTIVES: This study was conducted to compare the effects of Eugenia caryophyllus (clove) and Origanum compactum (oregano) EOs on the growth of Staphylococcus aureus and the expression of the SEA, SEC and SEE genes. METHODS: The minimum inhibitory concentrations (MIC) of EOs and growth of bacterium at subMIC levels of EOs was determined. Enterotoxin detection was done using a commercial SE visual immunoassay kit after 18, 24, 48 and 72 h. Gene expression of enterotoxins was evaluated through RNA extraction, DNA synthesis and performing real time-PCR using specific primers for each SE. RESULTS: MIC of clove and oregano were 2 µl/ml and 1µ l/ml, respectively. Colony counts at 48 and 72h of cultures grown at 75% MIC of clove oil showed the growth rate was reduced 1.67 and 1.83 log10 cfu/ml compared to the control, and in the case of oregano at 75% MIC the decreases in growth rate were 2.25 and 2.68 log10 cfu/ml, respectively. When the target bacterium is cultured in the presence 75% subMIC of EOs, the transcript levels of sea, sec, see and the regulatory gene (agrA) were decreased 8.81, 9.13, 9.08 and 8.32 fold in the case of clove, and 11.56, 9.96, 11.07 and 11.15 fold in the case of oregano, compared to the control. CONCLUSIONS: The growth, gene expression and as a result secretion of enterotoxins A, C and E by S. aureus were decreased significantly at subMIC levels of EOs, especially at 75% MIC.

Background: Wound infection has become a major medical problem in recent years. This is usually caused by Gram-positive bacteria, especially Staphylococcus aureus. Since antimicrobial resistance to current drugs has critically been developed in these causative microorganisms, substitution medicine has become one of the main interests within  researchers. OBJECTIVES: The aim of this study was to evaluate the healing activity of Origanum vulgare against surgical wounds infected by S. aureus. METHODS: Twenty male Sprague-Dawley rats were randomly divided into two groups. Excisions were created surgically on the animals’ skin and then infected with S. aureus. Group 1 was treated with an extract of O. vulgare while Group 2 was untreated. Wound biopsy specimens were collected on Days 5, 10 and 16 and analyzed. RESULTS: Results showed that the hydroxyproline content in the treatment group was significantly higher in various post wounding days. The mean of hexosamine in the treated group was higher than in the control group. Protein content increased gradually in Day 10. Results of histopathological studies showed moderate to intense granulation tissue formation and neovascularization in the treated group on Day 10. Furthermore, the histopathological studies showed that intense matrix formation and collagen fiber deposition occurred in treatment group on Day 16 post wound, while intense granulation tissue formation was the prominent feature in control group. CONCLUSIONS: The present study has demonstrated that the ethanol extract of O. vulgare contains properties that accelerate wound healing activities compared to control group.

BACKGROUND: Mastitis is an important disease that affects dairy herds worldwide. The Staphylococcus aureus (S. aureus) is the causative pathogen for mastitis. This pathogen has the tendency to biofilm forming, and may happen to antibiotic resistance. OBJECTIVES: The aim of this study was to characterize the biofilm formation of different genotypes and antibiotic resistance pattern of S. aureus isolated from the subclinical bovine mastitis in Tehran province. METHODS: The lactating dairy cows were screened for the subclinical mastitis. The isolates were identified by phenotypic method and the presence of the nuc gene. The biofilm forming and quantification was characterized using colorimetric assay. The S. aureus biofilm gene was evaluated using PCR assay. The antimicrobial susceptibility of the isolates was assessed using DAD method. The lowest antimicrobial concentration preventing the visible growth was construed by MIC50. The antibiotic susceptibility and MBECs for the bacteria embedded in the biofilms were determined by XTT method. RESULTS: The antimicrobials susceptibility test showed penicillin and ceftiofur to be less and more effective in vitro, respec-tively. The genotypic characterization showed that the highest and the lowest frequencies for icaD (75%) and fnbB (31.2%) genes, respectively. The biofilm formation was also characterized. The MBEC results for the bacterial biofilm showed resistance to ceftiofur in the biofilm state; however, these strains were susceptible to this agent in the planktonic state. CONCLUSIONS: The biofilm formation is a significant virulence factor that was detected at a high rate. It is antibiotic-resistant and responsible for the subclinical bovine mastitis that does not respond to the routine treatments.In order to control the infection achieve the effective treatment, and prevent the emergence of antibiotic-resistant bacteria, it is necessary to isolate the causative agent and determine the antimicrobial susceptibility

BACKGROUND: Staphylococcus aureus is a highly versatile pathogen of a large number of domestic ani- mals, including avian species. There is limited information about S. aureus isolated from companion and wild birds in Iran. OBJECTIVES: The aim of this study was to determine drug resistance and random-amplified polymorphic DNA-PCR (RAPD-PCR) pattern of S. aureus isolated from birds referred to the pet birds’ clinic of University of Tehran. METHODS: During the study period, 53 isolates of S. aureus were recovered from companion birds of var- ious species using standard bacteriologic procedures and the respective drug resistance patterns were deter- mined for a panel of 30 antimicrobial agents by agar disk-diffusion method. RAPD-PCR was performed with two different 10-bp oligonucleotide primers in a duplex-PCR procedure. RESULTS: The findings of this study demonstrated that S. aureus resistance to oxacillin, clindamycin and methicillin were 58, 53 and 53%, respectively. The multi-drug resistance (MDR) was found among all isolates. The MDR pattern was variable and ranged from 0 to 17 drugs. In total, all 53 isolates generated 43 different resistance patterns. In RAPD-PCR, five different patterns of A, B, C, D and E were found. Among 53 isolates, 20, 62, 3, 9 and 3% belonged to RAPD patterns of A, B, C, D and E, respectively. CONCLUSIONS: This study showed the widespread antimicrobial resistance among S. aureus isolated from pet birds; in particular, the presence of MRSA isolates. The value of RAPD-PCR for epidemiologic monitoring of S. aureus in pet birds also was noticed