Tehran University Medical Journal

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Background: Staphylococcus aureus is the most important cause of nosocomial infections acquired in the community. Protein A is a major component of Staphylococcus aureus cell wall. In analysis of the nucleotide sequence Protein A encoding spa, locus x consists of 24 base pairs which repeat with high polymorphism. In this study, the spa gene of Staphylococcus aureus isolated from clinical specimens were obtained from patients admitted to the hospital and healthy carriers. Methods: In a cross-sectional study, a total of 200 samples were collected. One hundred fifty samples were obtained from hospitalized patients and 50 samples obtained from staff nasal swabs in Hamadan University Hospitals from October 2013 to August 2014. Disk diffusion antibiotic susceptibility tests performed. The antibiotics studied were Vancomycin (30 µg), Cefoxitin (15 µg) Gentamicin (10 µg), Tetracycline (30 µg), Trimethoprim/sulfamethoxazole (25 µg), Ciprofloxacin (5 µg), Erythromycin (15 µg), Clindamycin (2 µg), Rifampin (5 µg). The tests performed according to the guidelines of clinical and laboratory standards institute (CLSI). It also detect the mecA gene of Methicillin-resistant Staphylococcus aureus strains (MRSA) and genes spa which encodes the protein A by polymerase chain reaction (PCR). The PCR products using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method with enzyme Rsa I (Afa I) were prepared. Results: This methicillin-resistant Staphylococcus aureus strain (MRSA) had the highest sensitivity and resistance to ciprofloxacin and clindamycin. Totally, 8 amplicon with different sizes for the spa gene were identified. A total of 9 patterns polymerase chain reaction- restriction fragment length polymorphism (PCR-RFLP) were found. Some of these patterns between Staphylococcus aureus isolated from clinical specimens and nasal carriers were common. Conclusion: There is a similar pattern of spa gene among patients admitted to the hospital and staff, according to our findings. Analysis of the patterns can reduced transmission of infection in both hospital staff and patients. Also it can help the physicians for correct management of infections.

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Background: Staphylococcus aureus is one the most common pathogens causing community-acquired infections and a major concern for public health, and the other hands antibiotic resistance is also of great concern for public health authorities also Staphylococcus aureus produce a lot of virulence factors such as variety of exoproteins included toxic shock syndrome and exfoliative toxin which causes colonization and different infections in their host. The aims of current study were to evaluate the prevalence of Toxic shock syndrome toxin 1 (TSST-1) and ETs genes in isolated S. aureus strains using polymerase chain reaction (PCR) assay. Methods: This cross-sectional study was performed on 100 methicillin-resistant staphylococcal aureus (MRSA) and 100 methicillin-sensitive staphylococcal aureus (MSSA) isolated from clinical specimens of inpatients, outpatients hospitals and nasal carriers in Hamadan University from October 2013 to August 2014. Identified species by biochemical methods were confirmed by the PCR method. Antibiotic resistance was performance by disk diffusion and the presence of TSST-1 and ETs genes was investigated using PCR. Results: Of the 100 isolates MRSA examined, the most frequent resistance was observed to ciprofloxacin (95%), followed by tetracycline (91%), erythromycin (92%), Gentamicin (90%), Rifampin (85%), trimethoprim-sulfamethoxazole (85%), clindamycin (80%) and cefoxitin (100%). Of the 100 isolates MSSA examined, the most frequent resistance was observed to erythromycin (68%), ciprofloxacin (66%), followed by tetracycline (52%), gentamicin (25%), clindamycin (46%), rifampin (45%), trimethoprim-sulfamethoxazole (66%) and cefoxitin (0%). Prevalence of TSST-1 and ETs genes were determined 13% (n=26) isolates, totally. Also the prevalence of TSST-1 was 11% (n=22) and ETs genes was 2% (n=4) isolates and none of the investigated isolates carried eta gene. Conclusion: The increasingly prevalence of MRSA and emerging its antibiotic resistance in clinical isolates can be considered a serious problem for public health. Detection of the high rate prevalence of TSST genes in current study is considered as a serious problem and existing and circle of these strains in according to colonization in community especially old people and immunocompromised patients is very serious.

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Background: Bloodstream infections (BSI) have a high incidence and high mortality in the worldwide. The mortality rate is variable between 20-70%. Therefore, early and timely detection of BSI agent in clinical laboratories is necessary. The aim of this study was to determine an efficient diagnostic tool to septicemia in accompany of blood culture method by Real-time PCR (using panbacterial 23S rRNA gene).

Methods: This cross-sectional study was conducted in two analytical and clinical stages in Hamadan University of Medical Sciences, Iran, from October 2014 to June 2015. In analytical stage, sensitivity (by serial dilution from 104 to 1 CFU/ml) and specificity of the primer were evaluated with the Staphylococcus aureus (as Gram positive indicator bacteria) and Escherichia coli (as Gram-negative indicator bacteria), human genome (from Hella cell culture), Candida albicans yeast and Aspergillus fumigatus fungus. In clinical stage, 121 blood samples were collected from patients suspected to sepsis in intensive care unit (ICU) from Hamadan University Hospitals. Finally, the results of Real-time PCR and blood culture methods were compared.

Results: The Real-time PCR showed a sensitivity ranging from 2 to 10 target copies per reaction to the whole blood for Escherichia coli and Staphylococcus aureus respectively. The specificity of this method was evaluated and no false positive amplification was identified. 57.85% (70 cases) of the samples were positive by Real-time PCR and 13.22% (16 cases) of the samples were positive by blood culture. However, none of the cases that were positive by blood culture were negative in Real-time PCR. As well as, 44.62% (54 cases) of cases were positive by Real-time PCR but blood culture showed no bacteria in the samples, and 42.15% (51 cases) were negative by both methods. Correlation or agreement of Kappa was 0.20, that indicating poor agreement between the two methods.

Conclusion: Real-time PCR is more sensitive than blood culture and also, because of high sensitivity of this primer by Real-time PCR, we can use it for screening blood samples from suspected patients of sepsis.

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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.

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Background: Multidrug-resistant bacteria make many problems in clinical therapy, design and manufacture of synthetic drugs. Pseudomonas aeruginosa is one of the most important multidrug-resistance bacteria leads to variety infections in human especially in immunocompromised, patients with severe burns, and nosocomial infections. It Recent years, this organism makes a big challenge in clinical treatment of infections using a wide range of antibiotics. Medicinal herbs for thousands of years to prevent or treat infectious diseases were considered. Today, pharmacists have high interest of using medicinal herbs to prepare a new antimicrobial compounds. The goal of this study was to investigation the effect of aqueous and alcoholic extract of fresh garlic on the expression of genes encoding elastase and exotoxin A virulence factors, in P. aeruginosa PAO1 strain.

Methods: Present study was an experimental study and performed from 2015 to 2016 in Hamadan University of Medical Science, Iran. The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of aqueous and alcoholic extract of garlic was determined. Then in order to investigation the gene expression of elastase and exotoxin A genes, quantitative real-time polymerase chain reaction (qPCR) method was performed at sub-MBC concentrations. Results: According to the results aqueous extracts of garlic had better impact in comparison with alcoholic alone. At concentration of 64 and 8 mg/ml of aqueous extract the expression of both elastase and exotoxin A genes were decreased. Although, the expression of elastase gene was most affected by garlic at different concentrations than exotoxin A.

Conclusion: The results suggested that the compositions of garlic extracts can inhibit the production of virulence factors in P. aeruginosa. So in order to treat infectious diseases in the near future, medicinal plants known as new antimicrobial drugs can be used alone or with antibiotic drugs against pathogenic bacteria.