فهرست مطالب پرویز اولیا

Contaminated foods with Shiga toxigenic serotypes of Escherichia coli (STEC) can cause diarrhea and severe diseases in consumers. The aim of this study was to investigate frequency of Shiga toxigenic Escherichia coli serotypes and their antibiotic resistance patterns in vegetable samples from Tehran, Iran.

In this study, a total of 97 vegetable samples from 22 urban areas of Tehran, Iran, were investigated, July 2018 to March 2019. To identify Shiga toxigenic Escherichia coli strains, standard method of enrichment and culture in selective media and polymerase chain reaction for verifying presence of stx1 and stx2 genes were used. Presence of eae and ehxA genes was investigated in Shiga toxigenic Escherichia coli isolates. Antibiotic resistance was assessed using disk diffusion method for 15 antibiotics and the multidrug resistance phenotype was assessed.

Shiga toxigenic Escherichia coli strains were isolated in 14/4% of vegetable samples (stx1, stx2, stx1/stx2 of 8, 1 and 5%, respectively). Presence of eae and ehxA genes was shown in 1 and 2% of Shiga toxigenic Escherichia coli isolates, respectively. The highest resistance was detected to trimethoprim-sulfamethoxazole (100%), erythromycin (73.33%) and tetracycline (85.7%) and the lowest against meropenem (0%) and imipenem/ceftazidime (7/7%).

In this study, contamination of vegetables with multidrug resistant Shiga toxigenic Escherichia coli was verified in Tehran, Iran. Further studies on human samples can clarify this contamination.

 Pseudomonas aeruginosa is an important ubiquitous and especially common pathogen in the hospital. Exotoxin A that encoded by exoA gene has a role in pathogenesis of this bacterium. Today, probiotics are widely used in the treatment and prevention of diseases. The present study aimed to study the Saccharomyces cerevisiae S3 effect on the expression of exoA gene.

 S. cerevisiae S3 supernatant and lysate were prepared. Subminimum inhibitory concentrations (sub-MIC) of extracts were used to P. aeruginosa PAO1. The level of exoA expression was measured with real-time PCR method.

Lysate extract had a reducing effect on toxin gene expression, but unlike lysate, supernatant had an increasing effect on gene expression.

 We demonstrated that S. cerevisiae S3 had an inhibitory effect on Exotoxin A virulence factor of P. aeruginosa. We suggest doing more experiments on the effect of S. cerevisiae on other virulence factors of P. aeruginosa and pathogens.

Methanotrophs are microorganisms that play an important role in reducing up to 15% of environmental CH4 concentration. These bacteria can oxidize methane to methanol. Methane is an atmosphere-polluting greenhouse gas with increasing atmospheric concentrations and is considered a serious threat to the environment and the sustenance of life on the planet. Possible unfavorable future weather and the extensive use of different types of pesticides necessitate the use of methanotrophic bacteria that are resistant to these conditions. The present study focused on the isolation and specific study of Methylocystis methanotrophic bacteria.

The bacterial strains were isolated from different environments such as wetlands, rivers, and paddy fields. The isolated strains were concentrated with Methane gas enriched cultures and purified by serial dilution-extinction, alternating liquid, and solid subcultures. Then, molecular identification was performed and a suitable culture medium was designed for Methylocystis strains in the name of Methylocystis Culture (MOC). Strains were cultured in MOC to evaluate their viability in different conditions by changing important parameters such as the temperature, pH, salinity, and drought. In addition, they were affected by pesticides. The methane gas reduction in the upper space of the culture medium of each strain, in accordance with the control samples, is considered as the methane oxidation of that strain.

Methane gas oxidation rate was determined in vitro for the cultures of several strains. The growth curve of the strains was plotted. According to the results, Methylocystis methanotrophs had high survivability in different conditions and were resistant to common pesticides, and consumed more than 75% of methane gas over a period of 14 days.

Methylocystis methanotrophic bacteria can greatly reduce the release of methane into the atmosphere and alter the fate of the atmosphere.

Salmonella is one of the most important bacteria that causes gastroenteritis in humans and the spread of Salmonella strains with multidrug resistance is an acute global problem. Integrons are one of the most important factors responsible for transfering of drug resistance genes among Salmonella serotypes. In the present study, the frequency of class 1 and class 2 integrons as well as their relationship with drug resistance patterns in patients with gastrointestinal symptoms were investigated.

In this cross-sectional study, 400 human fecal samples with gastrointestinal symptoms were collected from 4 hospitals in Tehran. All the samples were analyzed by standard method for microbial culture and the results were confirmed by biochemical and PCR tests. Antimicrobial susceptibility testing was performed by disk diffusion method. After DNA extraction, the presence of class 1 and 2 integrons was investigated by PCR. Statistical analysis for detection of correlation between the presence of integrons and resistance patterns was done using SPSS software and Fisherʼs exact test.

The results showed that Salmonella was present in 5.5% (22.400) of the stool specimens. The prevalence rates of class 1 and 2 integrons for human stool specimens were 40.9% (9/22) and 27.2% (6/22), respectively. MDR phenotype was detected in 4.5% (1.22) of the Salmonella isolates from patients with gastroenteritis.

In this study, high levels of integrons 1 and 2 were observed in the patients' Salmonella isolates with gastroenteritis. The observed relationship between drug resistance patterns and the integrons indicated a possible increased risk of drug resistance genes in Salmonella isolates with human gastroenteritis.

Salmonella is considered as a main cause of community-acquired diarrhea in humans, however, sources of the multi-drug resistant (MDR) strains and their link with the disease are not well known.

This study aimed to investigate the frequency, serogroup diversity, and antimicrobial susceptibility patterns of Salmonella strains in poultry meat and stool samples of patients with community acquired diarrhea in Tehran.

We compared the frequency of non-typhoidal Salmonella serogroups, the similarities of their resistance patterns to 10 antimicrobial compounds, the prevalence of extended spectrum β-lactamase (ESBL) and ampicillinase C (AmpC) genetic determinants, and class 1 and 2 integrons in 100 chicken meat and 400 stool samples of symptomatic patients in Tehran during June 2018 to March 2019.

Salmonella was isolated from 75% and 5.5% of the chicken meats and human stool samples, respectively. The chicken meat isolates mainly belonged to serogroup C (88%, 66/75), while the human stool isolates were mainly related to serogroup D (59.1%, 13/22). The MDR phenotype and the most common rates of resistance to antibiotics, including tetracycline, trimethoprim/sulfamethoxazole (TS) and azithromycin, were detected in 4.5% and 45.3%, 59% and 13.6%, 43% and 9.1%, 42% and 9.1% of the human stool and chicken meat samples, respectively. Carriage of blaCTX, blaSHV, and blaPER genes in the meat isolate with ESBL resistance phenotype and blaACC, blaFOX, and blaCMY-2 among the 7 meat strains with AmpC resistance phenotype was not confirmed using polymerase chain reaction (PCR). High prevalence of class 1 and 2 integrons was characterized and showed a correlation with resistance to TS and chloramphenicol.

These findings showed a lack of association between chicken meats and human isolates due to discrepancy between the characterized serogroups and resistance phenotypes.

Campylobacter species are among foodborne pathogens that are known as the main cause of inflammatory diarrhea in humans. In this cross-sectional study, we investigated the prevalence of Campylobacter spp. and their drug resistance status in fecal samples of patients with community-acquired gastroenteritis in Tehran.

In this survey, infection with Campylobacter spp. was evaluated in 400 stool samples of patients with diarrhea. Accordingly, microscopic examination to show the presence of exudative diarrhea, rejection of fungi and parasitic infections, enrichment and culture in a specific medium under microaerophilic conditions, determination of biochemical identity, and molecular confirmation at genus and species levels for C. jejuni, C. coli, C. lari, and C. upsaliensis were performed. Antibiotic resistance patterns were determined by E-test and disk diffusion methods, and the presence of the dominant gyrA gene mutations in the quinolone-resistance domain of C. jejuni isolates was determined by using Mismatch Amplification Mutation Assay-polymerase chain reaction (MAMA-PCR)[1].

A total of 28 strains of Campylobacter were isolated from the samples obtained from the patients with diarrhea. The most common species were C. jejuni (6%), C. coli (0.5%), C. lari (0.25%), and other unknown species (0.25%). The highest antibiotic resistance rate was observed against tetracycline and ampicillin (53.5% and 50%, respectively), and the lowest rate was detected for nalidixic acid and ciprofloxacin (28.5% and 28.5%). Multiple drug resistance (MDR) phenotype was detected among 51.8% of the strains.

Results of this study indicated C. jejuni as the main Campylobacter species responsible for community-acquired diarrhea among the studied patients. The high rate of resistance to antibiotics and MDR phenotype in these strains compared with other countries is considered a risk, especially in the treatment of invasive infections.

Pseudomonas aeruginosa is one of the most common opportunistic bacteria in nosocomial infections, which has a significant resistance to antimicrobials. Due to the restrictions in the use of antibiotics, the tendency to replace them with natural products has increased. In this study, the antimicrobial effect of four species of Satureja essential oils (S. mutica, S. bachtiarica, S. rechingeri and S. khuzestanica) on virulence factors of P. aeruginosa was evaluated. The minimum inhibitory concentration of Satureja essential oils was determined by microdilution broth method against standard strains of P. aeruginosa including PAO1 and 8821M. In the following, the effect of sub-minimum inhibitory concentrations (sub-MIC) of essential oils was investigated on virulence factors of this bacterium including motility, biofilm formation and alginate, elastase, and alkaline protease production of these two strains. All four Satureja essential oils had antimicrobial effects against the standard strains of P. aeruginosa, and also sub-MIC concentrations of the essential oils significantly reduced the virulence factors production of these strains. In this study, the suitable antagonistic effects of Satureja essential oils were observed against P. aeruginosa standard strains. By further study, these essential oils can be used as an antimicrobial compound against this bacterium.

One of the major issues in food hygiene and safety is the emergence of antibiotic-resistant bacteria. Pathogens as well as biofilm formation can play a role in increasing bacterial resistance. In this study, biofilm formation in Salmonella isolates from chicken, drug resistance and drug resistance pattern were investigated.

In this study, 75 samples of chicken infected with Salmonella bacteria were studied. The rate of biofilm formation was assessed by microtiter plate method. Drug resistance and evaluation of drug resistance pattern were also evaluated.

The results showed that in 92% (69/75) of the samples Salmonella biofilm were formed, among which the moderate biofilm with 65.2% had the highest biofilm production. Concurrent resistance to 2 classes of antibiotics (2DR) with 31.8% (22/69) was the most common type of multidrug resistance (MDR) among the biofilm-forming isolates. Resistance to imipenem, ceftriaxone and cefotaxime was observed in only 1 biofilm formation sample.

In this study, high biofilm formation was observed in Salmonella contaminated chicken meat samples. The high rate of antibiotic resistance in biofilm constituents is due to the increasing attention to hygienic aspects of non-transmission of food contamination to humans.

Klebsiella pneumoniae is one of the most important bacteria that cause nosocomial infections. This opportunistic pathogen has a high potential for antibiotic resistance and can generate a thick layer of biofilm. Nowadays, antibiotic resistant strains are emerging and widely spreading worldwide. Thus, it is necessary to combat drug-resistant strains through the use of novel drugs (such as medicinal plants).

This study aimed to evaluate the in vitro antibacterial activity of Satureja rechingeri Jamzad, S. khuzestanica Jamzad, S. bachtiarica Bunge, and S. mutica Fisch. & C.A.Mey. essential oils against K. pneumonia ATCC 700603.

For evaluation of the minimal inhibitory concentration (MIC) of essential oils, broth microdilution method was used. The microtiter plate assay method was used for the assessment of anti-biofilm activities of sub-MIC value of essential oils. Colorimetric and Iodometric assays were used for determination of urease and beta-lactamase activity.

According to data collected, the MIC value of essential oils was 4096 µg/mL. sub-MIC value of essential oils inhibited biofilm formation and urease activity of K. pneumoniae. However, S. khuzestanica had more activity. None of the essential oils caused a significant decrease in beta-lactamase activity of K. pneumoniae.

Based on our analysis S. khuzestanica had a good antibacterial, anti-biofilm activities and urease inhibitory effects against K. pneumoniae, but additional studies are required to investigate the exact mechanisms of the antibacterial action and functions of this phytocompound.

Pathogenic species of Campylobacter, in addition to diarrhea and gastrointestinal diseases, could cause debilitating auto-immune and chronic diseases in humans. Investigation of the existence of this bacterium in food sources and clinical samples, and detection of antibiotic resistance could be helpful in the control of its spread and treatment procedures. The aim of this study was to evaluate the frequency and antibiotic resistance of Campylobacter isolates isolated from poultry meat.

In this study, a total of 100 poultry meat samples were collected from 22 districts of Tehran from July 2018 until March 2019. Accordingly, standard enrichment of the collected samples and their culture in selective medium was done. The isolates were characterized biochemically and by polymerase chain reaction for genus and species specific primers for C. jejuni, C. coli, C. upsaliensis, and C. lari. Antimicrobial susceptibility of the isolates to 7 antibiotics were done using E-test and disk diffusion methods. Moreover, resistance to three or greater classes of antibiotics was determined as multiple drug resistance phenotype (MDR) and the results were statistically analyzed using SPSS16 software.

Campylobacter was isolated from 35% of the poultry meat samples. C. jejuni (23%), C. coli (1%), and C. lari (1%) were among the Campylobacter isolates from these samples. Highest resistance phenotype and the lowest ones were detected against tetracycline (62.8%), and ampicillin and clindamycin (17.1%, each one), respectively. The MDR phenotype was detected among 42.8% of the isolates.

Our results showed high level of contamination with Campylobacter in the poultry meat samples which proposed increased risk of the infection with MDR strains among the consumers in Tehran. Further studies on human clinical samples could better determine this correlation.

Salmonella is one of the leading causes of foodborne illnesses worldwide which has become an important issue today due to the increasing drug resistance. This study was aimed to detect the frequency and diversity of Salmonella serogroups and drug resistance patterns among poultry meat samples distributed in Tehran, Iran.
 
In this cross-sectional study, 100 samples of poultry meat were prepared from authorized distributors of meat products from 22 districts of Tehran. All samples were analyzed by standard method and characterization of the isolates were done using biochemical, polymerase chain reaction, and serogrouping methods. Antibiogram was done using disk diffusion method.
 
The results showed that Salmonella was present in 75% (75/100) of the chicken meat samples. Chicken meat isolates were predominantly belonged to serogroup C (88%, 66/75), while other isolates belonged to serogroup B (2.6%, 2/75), serogroup D (5.3%, 4/75), and non-group A–D Salmonella isolates (5.3%, 4.75). While resistance to tetracycline (59%) was the most common resistance phenotype in these isolates, concurrent resistance to 3 classes of antibiotics (3DR) was the most common type of multidrug resistance (MDR) phenotype among them.
 
In this study, high rate of contamination with Salmonella was observed in the chicken meat samples. Dominance of antibiotic resistance in these isolates showed their possible risk for transmission of resistance gene markers to the human gut microbiota through food chain.

Probiotics are useful microorganisms for health of communities. Saccharomyces cerevisiae is one of the effective microorganisms for treating of functional and gastrointestinal diseases in order to control pathogens. Enterohemorrahgic Escherichia coli (EHEC) and Enterotoxogenic (ETEC) are common pathogenic strains in all the world. The aim of this study was to evaluate the inhibitory effect of S. cerevisiae probiotic yeast on the growth of ETEC and EHEC. For preparation of the supernatant extract, the yeast suspension was centrifuged, and then, the supernatant was filtered. Extraction with ethyl acetate was performed in three hours. For preparation of lysate, the precipitate was washed and centrifuged. The supernatant was removed and sterilize distilled water was added. Cell lysis was performed by sonication and the liquid was centrifuged and filtered. Then, the MIC and MBC were determined by micro dilution method. The concentration range was 16-8192 μg/ml. The MIC and MBC of the supernatant against both ETEC and EHEC were 4096 μg/ml and 8192 μg/ml, respectively. Lysate in any of the concentrations showed no inhibitory effects on strains. The supernatant of S. cerevisiae has an inhibitory effect on growth of ETEC and EHEC. The lysate, probably due to the richness of the nutrients required for bacterial growth and not containing antibacterial compound, did not lead to such a repressive effect.

Treatment of Staphylococcus aureus (S. aureus) infection is a problematic subject in the world. The aim of this study was an evaluation of the antimicrobial effect of four species of Satureja essential oils on biofilm formation and hemolysin production in S. aureus. MIC of Satureja essential oils (Satureja khuzistanica Jamzad, Satureja bachtiarica Bunge, Satureja rechingeri Jamzad, Satureja mutica Fisch. & C. A. Mey.) were determined by micro dilution broth method against standard strains of S. aureus ATCC 29213(MSSA) & ATCC 33591(MRSA). Sub- MICs of Satureja essential oils were used to assay biofilm formation and hemolysin production. The results showed that all essential oils had antimicrobial effect against standard strains of S. aureus. In the presence of sub- MICs of essential oils, biofilm formation and hemolysin production were significantly reduced. The results show the potent antimicrobial effects of Saturejaessential oils against S. aureus and more study is recommended to use it in controlling S. aureus infections.

Pseudomonas aeruginosa is a potent pathogen for humans using multiple virulence factors. The purpose of this study was to investigate the effect of Saccharomyces cerevisiae lysates and supernatants on biofilm, alginate factors. First, the supernatant extract and lysate were prepared from the native strain of Saccharomyces cerevisiae and turned into dry powder. Then, supernatant and lysate extracts were admixed with Pseudomonas aeruginosa strain PAO1 and strain M 8821, respectively, and biofilm in the strain PAO1 and alginate in strain 8821 M by Colorimetric method is measured by reading Optical Density(OD) also mention to the wave length. Supernatant with MIC concentration of 1/2 in both experiments and all concentrations of lysates in biofilm test and the highest concentration of lysates in alginate test were used. Supernatant of Saccharomyces cerevisiae at a concentration of 1 / 2MIC (0.512 mg / ml) with P <0.05 significantly reduced the production of alginate in Pseudomonas aeruginosa 8821 M strain, but did not affect biofilm in Pseudomonas aeruginosa PAO1 strain respectively, with all concentrations and the highest concentration (8.192 mg / ml) with P <0.05 significantly reduced the production of biofilms in Pseudomonas aeruginosa strain PAO1 and alginate in Pseudomonas aeruginosa 8821 M strain. Saccharomyces cerevisiae is one of the options that probiotic studies can examine its effects on virulence pathogens, but requires the ultimate goal of producing probiotic drugs.

The use of high amounts of a variety of antifungal drugs for treatment of Candida albicans infections is effective in inducing resistance to these drugs. Saccharomyces boulardii is a non-pathogenic yeast used as a probiotic in prevention and treatment of diarrhea diseases. There is evidence of the inhibitory effect of this yeast on Candida albicans virulence factors.
Saccharomyces boulardii extract was obtained from filtered culture in YNB and PDB culture media. Antifungal activity of S. boulardii extract against C. albicans (fourteen clinical isolates and standard strain ATCC10231) was performed by the micro broth dilution method according to M27-A3 CLSI. The chemical composition of the extract was determined by the GC/MS method.
Dry substance obtained from 1 liter of YNB culture was 20 mg/ml whereas that of PDB culture was 50 mg/ml. S. boulardii extract did not show any fungicidal and inhibitory effect against C. albicans isolates. Substances obtained from PDB and YNB cultures and used in this experiment showed similar results. Eleven compounds representing 86.18 % of the extract were identified. The major constituents of yeast extract were Tyrosol (37.08%) and Phenylethyl Alcohol (26.75%).
The major constituents of yeast extract were Tyrosol (37.08%) and Phenylethyl Alcohol (26.75%). This study confirms that S. boulardii extract did not show any fungicidal and inhibitory effect against C. albicans isolates.

According to definition of probiotics by WHO/FAO that is “Live microorganisms which, when present in sufficient amount, confer beneficial effects to the host”.
Saccharomyces cerevisiae is the first non-pathogenic yeast which is known as a probiotic for humans that its helpful effects for humankind has been proved. Pseudomonas aeruginosa is one of the most significant opportunistic pathogen that has notably resistance to many antibacterial agents. This study evaluated the effect of Saccharomyces cerevisiae on the pathogenic factors of Pseudomonas aeruginosa such as elastase, alkaline protease, and motility.
In this study, we used local strain of Saccharomyces cerevisiae, which has the probiotic property and Pseudomonas aeruginosa )PAO1 strain). In order to investigate the effect of Saccharomyces cerevisiae (supernatant-lysate) on Pseudomonas aeruginosa, appropriate phenotypic tests were used.
The extract of Saccharomyces cerevisiae from local strain has inhibitory effects against Pseudomonas aeruginosa. Three factors involved in Pseudomonas aeruginosa pathogenicity, which was studied in this research (elastase, alkaline protease, and motility), to the acceptable extent, controlled and inhibited.
According to results of this study, Saccharomyces cerevisiae has reducing effects against Pseudomonas aeruginosa, which with more extensive research in this field, it can be used as a promising and innovative way to treat infection of this bacteria.

Saccharomyces cerevisiae is one of the probiotic yeasts that has positive effects on health. Pseudomonas aeruginosa is one of the important opportunistic pathogenic bacteria. The purpose of this study was to determine the effect of supernatant of Saccharomyces cerevisiae on preventing the growth of Pseudomonas aeruginosa and its effect on exotoxin S gene expression by Real-Time PCR method.
Pseudomonas aeruginosa was cultured in brain heart broth. Total RNA extraction was done by RNA Protect Bacteria kit and cDNA extraction was performed with QuantiTect Reverse Transcription kit. Saccharomyces cerevisiae was cultured in potato dextrose broth culture media and its supernatant was gained. Minimal Inhibitory Concentration (MIC) test for supernatant against P. aeruginosa was done by micro dilution broth method three times. The bacterial suspension of P. aeruginosa was admixed three times with pure culture, supernatant yeast. Each Real-Time PCR test was performed with a QuantiTect SYBER Green PCR kit to measure the expression of Exotoxin S gene.
Supernatant Minimal Inhibitory Concentration (MIC) test against Pseudomonas aeruginosa was 2048 µg/ml. The results of Real-Time PCR test represent the Exotoxin S gene expression efficiency in the culture of bacteria and supernatant was 1.77.
Supernatant of Saccharomyces cerevisiae could prevent the growth of Pseudomonas aeruginosa, but increases the expression of Exotoxin S gene in Pseudomonas aeruginosa, because supernatant 1/2 MIC concentrations was used and the gene expression efficiency number was greater than 1.

Microorganisms are present not only in common environment, but also in extreme environments. Salt lakes with near or at saturating salinity are spread all over the world. Urmia Salt Lake is one of these hypersaline environments. The present study aimed at evaluating prokaryotic diversity in hypersaline environment by culture-independent method. In this experimental study, different regions of Urmia Lake were sampled and the genomic material extracted from the water sample was used as a pattern for the amplification of 16S rDNA and a fragment of the bop gene via polymerase chain reaction. By cloning, each of the amplified fragments belonging to a single strain was amplified by T/A cloning vector. To further investigate the biodiversity of Haloarchaea, the biodiversity of bop gene was studied in addition to studying 16S rDNA. By cloning and sequencing, 6 bacteria genera, including Acaryochloris, Adhaeribacter, Brachybacterium, Gloeocapsopsis, Cesiribacter, and Bacillus were identified. Archaeal library belonged to 5 genera, including Halonotius, Halolamina, Haloquadratum, Halomicroarcula, and Halorhabdus. The clone libraries of bacterial belonged to 4 phyla, including Bacteroidetes, Cyanobacteria, Actinobacteria, and Firmicutes. . The clone libraries of bop gene (as a molecular marker) belonged to genera, including Halorubrum, Natrialba, Haloquadratum, and Natrinema. The bop phylogeny was closely related to the 16S rDNA phylogeny. By cloning and sequencing, 6 bacteria genera, including Acaryochloris, Adhaeribacter, Brachybacterium, Gloeocapsopsis, Cesiribacter, and Bacillus were identified. The bop phylogeny is closely related to the 16S rDNA phylogeny.

Microbial contamination of dental units is always a health problem in dentistry. This infection can be transmitted to patients. This study was done to evaluate the rate of bacterial contamination of water in dental unit of Shahed University, in particular by Escherichia coli (E. coli).
A total of 42 water samples from 7 dental units (endodontic, restorative, prosthetics, surgery, periodontics, implants and children) were taken. The sample was obtained from the tip of turbine. Also, seven samples from municipal water were taken as controls. For isolation and counting of total bacteria, blood agar medium and for E.coli isolation, EMB medium were used.
Gram positive bacilli were isolated most prevalently from samples, and Gram positive cocci and Gram-negative bacilli. E. coli contamination was not seen in any samples. The amount of total contamination was higher in the morning than in the afternoon and most contamination was seen in periodontics and surgery units.
In the present study, it was found out that the tip of turbines has a lot of pollution. Several ways are suggested for control of contamination. In this study, it was shown that the work by devices and leaving of water in the morning, before its use for the patient, can greatly reduce the microbial load.

Biofilm formation is an important virulence factor in Staphylococcus aureus. Most infections associated with biofilm of this bacterium are difficult to treat with antibiotics. As yet, a lot of mechanisms have been explained for probiotic yeast functions against bacterial infections, but few studies have been done on their effects on biofilm formation. The aim of this study was to evaluate the effect of Saccharomyces cerevisiae yeast on Staphylococcus aureus biofilm formation.
Extract of supernatant and lysate was prepared from Saccharomyces cerevisiae culture. After determining the MIC, the effect of extracts at three concentrations of 2048, 1024 and 512 µg/ml was evaluated on biofilm formation of two standard strains of S. aureus, ATCC 29213 (methicillin-sensitive) and ATCC 33591 (methicillin-resistant) using the microtiter plate assay in three replications.
Both supernatant and lysate extract of yeast could significantly reduce the biofilm formation of both methicillin-sensitive and resistant strains of S. aureus at all concentrations. While both studied strains were strong biofilm producers, at the concentration of 2048 µg/ml, supernatant could reduce their biofilm formation to moderate level. Also, lysate reduced biofilm formation to weak level more effectively.
In this study, the good effect of S. cerevisiae yeast on the reduction of S. aureus biofilm formation was observed for the first time. Doing more studies, it is expected to treat infections caused by biofilm of this bacterium with probiotic yeasts.

Bordetella pertussis is a gram-negative cocobacilli bacterium and etiologic agent of whooping cough that in recent years, the number of its cases is on the rise. The ability of biofilm production helps this bacterium in interference with host immune system, severity of illness and antibiotic sensitivity. Thus, due to the importance of this factor, in this investigation, we tested the ability of Bordetella pertussis isolates in biofilm formation.
Nasopharyngeal samples were collected from persons who suspected whooping cough from throughout of Iran from 2014 to 2016 and were transferred to pertussis reference laboratory in Pasteur Institute of Iran. The bacterium in question was isolated by culture so that finally we had 20 positive samples. At the end, we performed in vitro biofilm formation test for isolated strains.
All of the 20 clinical samples of Bordetella pertussis which in this study were examined could form biofilm and their final OD became between 0.606 and 1.212, the power of the biofilm made by them was intermediate.
Findings of this study was similar to researches conducted by other researchers, which showed the ability of the strains of Bordetella pertussis to form biofilm and to create adverse effects on the host for example antibiotic resistance, illness severity, and so on. Thus, considering the importance of this issue, more and broader researches are needed in this area.

Adamantanes, amantadine, and rimantadine have been used for many years for prevention and treatment of influenza virus A infections. These drugs are influenza virus M2 protein inhibitors and some amino acids substitutions in transmembrane portion of this protein cause resistance to them. This study was done for survey of adamantane resistance related nucleotide sequence changes in M2 gene of H1N1 and H3N2 subtypes isolated from Iranian patients in 2014.
Materiasl and Nasal swabs of patients with influenza-like symptoms were collected from Tehran through winter 2014 and were examined by Real Time Reverse Transcription PCR to evaluate presence of subtypes of H1N1 and H3N2 of influenza viruses A in them. Then, some positive samples for these viruses were propagated in cell culture. Four isolates from each subtype were randomly selected for M gene amplification by Reverse Transcription PCR and genetic analysis.
The study of point mutations in M2 gene sequence of isolates showed presence of most prevalent adamantane resistance related mutation; substitutions of serine with asparagine in amino acid 31; in all of them. Other mutations conferring resistance to adamantanes were not found.
According to results of this study and reports from other investigators, which showed the high prevalence of adamantane resistant mutants in human influenza virus A isolates, it is recommended that adamantanes not be used for the treatment of influenza.

Shigella spp. are gram negative bacteria that can cause shigellosis in human. It is important in young children as well as elderly and immunocompromised people. Threatening complications can occur in severe cases with multidrug resistance species. It has been observed that Shigella spp. have become resistant to antibiotics like other bacteria. Investigation of resistance to azithromycin, tetracycline and pattern of resistance are the objectives of this study.
Fifty isolates of Shigella spp. which have been collected from three hospitals in Tehran were studied. Isolates identified and confirmed as Shigella spp. by biochemical, serological and molecular methods (ipaH, wbgz, rfc genes). Antimicrobial susceptibility test was performed for ampicillin, azithromycin, ciprofloxacin, doxycycline, levofloxacin, minocycline, nalidixic acid, norfloxacin, streptomycin, trimethoprim-sulfamethoxazole and tetracycline by disc agar diffusion method. Minimal inhibition concentrations were performed for azithromycin and tetracycline.
From a total of 50 Shigella spp. isolates, 16% of them were Shigella flexneri and 84% Shigella sonnei. The majority of isolates were multidrug resistant. The most resistance was seen to doxycycline, streptomycin, trimethoprim-sulfamethoxazole and tetracycline. Resistance to azithromycin was 6% and all of the isolates were susceptible to norfloxacin and levofloxacin. Nine patterns of resistance were revealed to these isolates.
High resistance to tetracycline was observed and resistance to azithromycin as an alternative treatment choice was also considerable.

Pseudomonas aeruginosa is a gram-negative pathogen and one of the main causes of nosocomial infections with its multiresistance mechanisms, is known as the second important cause of infections that despite of existence of several antibiotics, the treatment against it is so difficult. This study has been done to detect the antibacterial sensitivity of P.aeruginosa with the use of two methods of disk-diffusion and microdilution and then to compare between them.
100 clinical isolates of Pseudomonas aeruginosa were collected from selected hospitals of Tehran and then after identification, the resistance pattern of the bacteria were studied with two methods of diskdiffusion and microdilution for these antibiotics: Ampicillin/Sulbactam, Piperacillin, Carbenicillin, Imipenem, Cefteriaxone, Ceftazidime, Cefoperazone, Gentamicin, Tobramycin, Amikacin, Chloramphenicol, Tetracyclin, Ciprofloxacin; then the results were analyzed by statistical tests.
The rate of resistance with the method of disk-diffusion was in the range of 28-100 percent for imipenem and tetracycline and with the method of microdilution was in the range of 30-97 percent for imipenem and ampicillin/sulbactam. Also, K-value which is used for survey of agreement between two methods used in this study, was 0.0 for tetracycline and more than 0.0 for other antibiotics.
P.aeruginosa has the maximum sensitivity to imipenem with both methods, so it is suggested to specialists for clinical use. The results have high agreement in all antibiotics except Tetracycline so the disk-diffusion method has a proper sensitivity for detection the antibacterial resistance of P.aeruginosa as well as microdilution method.

The global increase in resistance to antibiotics among clinical isolates of Acinetobacter baumannii is reported from several countries, but its true prevalence in Iran is less known. The objective of this study was determination of the frequency of resistance to different antibiotics among Acinetobacter baumannii isolated from patients in two hospitals in Tehran, Iran, in 2013, to help selection of antibiotics in empirical therapy of infection with these isolates. Disk diffusion method according to recommendation of CLSI was used for determination of resistance to 18 antibiotics from 8 different groups (aminoglycosides, carbapenems, cephalosporins, penicillins/ß-lactamase inhibitors, antipseudomonal penicillins/ß-lactamase inhibitors, fluoroquinolones, folate pathway inhibitors and tetracyclines) in 106 Acinetobacter baumannii clinical isolates. Frequency of resistance to antibiotics among Acinetobacter baumannii isolates were as follows: cefotaxime 99%, ciprofloxacin, ceftriaxone, cefepime, ceftazidime, ticarcillin-clavulanic acid, meropenem and trimethoprim-sulphamethoxazole 98.1%, tetracycline 97.4%, levofloxacin and piperacillin-tazobactam 97.2%, amikacin, imipenem 97.1%, gentamicin 89.6%, ampicillin-sulbactam 83%, tobramycin 77.4%, doxycycline 60.4% and minocycline 50.9%. All Acinetobacter baumannii clinical isolates have shown multidrug resistance (resistance to at least one agent in ≥3 antimicrobial group) and some of resistance patterns were more commonly seen. The high frequency of antibiotic resistance in clinical isolates of Acinetobacter baumannii in Iran as shown in this study makes epidemiological surveillance of susceptibility of these bacteria more essential.