Intestinal Colonization by Campylobacter jejuni, Clostridium difficile, and Clostridium perfringens among Commensal Rattus norvegicus in the Urban Areas of Tehran, Iran.

Background: Rattus norvegicus (R. norvegicus) population plays a significant role in the spread of numerous diseases in urban environments. The present study is aimed at investigating the presence of Campylobacter jejuni (C. jejuni), C. coli, Clostridium difficile (C. difficile), C. difficile toxigenic, and C. perfringens in R. norvegicus captured from urban areas of Tehran, Iran. Methods: From October 2021 to October 2022, 100 urban rats were trapped in 5 different districts of Tehran, Iran. The genomic DNA was extracted from fecal samples, and the presence of C. jejuni, C. coli, C. perfringens, and C. difficile species was evaluated using PCR assay. Moreover, PCR was used to assess the toxicity of C. difficile isolates. Results: Overall, 30% (n = 30/100) of fecal samples were positive for zoonotic pathogens. Based on the PCR on hippuricase (hipO), glycine (gly), CIDIF, and phospholipase C (plc) genes, C. perfringens and C. difficile were isolated from 18.2% (n = 14/77) and 5.2% (n = 4/77) of male rats. The highest frequency of C. perfringens and C. jejuni was 25% (n = 5/20) related to the south of Tehran. Toxigenic C. difficile was not detected in all regions. Conclusion: According to the findings, rats are the main reservoirs for diseases. Therefore, rodent control coupled with the implementation of surveillance systems should be prioritized for urban health.

Comparative analysis of genes expression involved in type II toxin-antitoxin system in Staphylococcus aureus following persister cell formation.

BACKGROUND: The formation of persister cells is the main reason for persistent infections. They are associated with antibiotic treatment failure and subsequently chronic infection. The study aimed to assess the expression of type II toxin/antitoxin (TA) system genes in persister cells of Staphylococcus aureus in the presence of the following antibiotics vancomycin, ciprofloxacin, and gentamicin in exponential and stationary phases. METHODS AND RESULTS: The colony count was used to evaluate the effect of different types of antibiotics on S. aureus persister cell formation during exponential and stationary phases. Moreover, the expression level of TA systems and clpP genes in the persister population in exponential and stationary phases were measured by quantitative reverse transcriptase real-time PCR (qRT-PCR). The results of the study showed the presence of persister phenotype of S. aureus strains in the attendance of bactericidal antibiotics in comparison to the control group during the exponential and stationary phases. Moreover, qRT-PCR resulted in the fact that the role of TA systems involved in the persister cell formation depends on the bacterial growth phase and the type of strain and antibiotic. CONCLUSIONS: In total, the present study provides some data on the persister cell formation and the possible role of TA system genes in this process.

Glucomannan enhanced the macrophage activity in exposure to methicillin-resistant Staphylococcus aureus (MRSA): in-vitro study.

Background and Objectives: The increasing number of methicillin-resistant Staphylococcus aureus persuade the need for preventive measures. Glucomannan is a polysaccharide choice for developing immunological strategies. This study aimed to investigate changes in gene expression and phagocytic activity of macrophage cells in the presence of glucomannan. Materials and Methods: The effect of different concentrations of glucomannan (25, 50, and 100 µg/mL) on the phagocytic activity of macrophage cells was measured using the colony count method. The expression of Tumor Necrosis Factor-alpha (TNF-α) and Inducible Nitric Oxide Synthase (iNOS) genes was evaluated by Real-Time PCR. Results: The concentrations of glucomannan significantly reduced the bacterial Colony-Forming Unit (CFU) and increased the phagocytic activity of macrophage cells. The maximum effect of glucomannan on iNOS and TNF-A genes expression was 100 µg/mL. Conclusion: Glucomannan should be considered an adjuvant that stimulates the immune system. It may increase the expression of TNF-α and iNOS genes and the phagocytic activity of macrophage cells against methicillin-resistant Staphylococcus aureus.

Evaluation of Chlamydia trachomatis Genotypes in Endocervical Specimens by Sequence Analysis of ompA Gene among Women in Tehran.

Tehran's actual prevalence of Chlamydia trachomatis (CT) and its genotypes are still unclear. Molecular typing of CT strains can provide essential epidemiological knowledge and contribute to improved control measures. In this study, we aimed to determine the prevalence of CT and its genotypes in the endocervical infections of females who attended the gynecology and infertility clinics in Tehran. A total of 291 women were tested for chlamydial infection by in-house PCR using specific primers for the CT cryptic plasmid. Nested PCR for amplification of the ompA gene in positive samples was carried out, genotyping was performed by sequencing this gene, and further phylogenetic analysis was conducted. Sexual infection by CT was observed in 10.3% (30/291) of the subjects, and the mean age of patients was 30.4. The ompA gene was sequenced in 27 samples, revealing E genotypes 40.7%, (n = 11), F 25.9%, (n = 7), G 18.5%, (n = 5), D 11.1%, (n = 3), and K 3.7%, (n = 1). This study emphasizes the importance of the diversity among CT genotypes in our studied population and the need for wide-screening the neglected bacterial infection among women in Tehran.

Reverse vaccinology approaches to introduce promising immunogenic and drug targets against antibiotic-resistant Neisseria gonorrhoeae: Thinking outside the box in current prevention and treatment.

Gonorrhea is an urgent antimicrobial resistance threat and its therapeutic options are continuously getting restricted. Moreover, no vaccine has been approved against it so far. Hence, the present study aimed to introduce novel immunogenic and drug targets against antibiotic-resistant Neisseria gonorrhoeae strains. In the first step, the core proteins of 79 complete genomes of N. gonorrhoeae were retrieved. Next, the surface-exposed proteins were evaluated from different aspects such as antigenicity, allergenicity, conservancy, and B-cell and T-cell epitopes to introduce promising immunogenic candidates. Then, the interactions with human Toll-like receptors (TLR-1, 2, and 4), and immunoreactivity to elicit humoral and cellular immune responses were simulated. On the other hand, to identify novel broad-spectrum drug targets, the cytoplasmic and essential proteins were detected. Then, the N. gonorrhoeae metabolome-specific proteins were compared to the drug targets of the DrugBank, and novel drug targets were retrieved. Finally, the protein data bank (PDB) file availability and prevalence among the ESKAPE group and common sexually transmitted infection (STI) agents were assessed. Our analyses resulted in the recognition of ten novel and putative immunogenic targets including murein transglycosylase A, PBP1A, Opa, NlpD, Azurin, MtrE, RmpM, LptD, NspA, and TamA. Moreover, four potential and broad-spectrum drug targets were identified including UMP kinase, GlyQ, HU family DNA-binding protein, and IF-1. Some of the shortlisted immunogenic and drug targets have confirmed roles in adhesion, immune evasion, and antibiotic resistance that can induce bactericidal antibodies. Other immunogenic and drug targets might be associated with the virulence of N. gonorrhoeae as well. Thus, further experimental studies and site-directed mutations are recommended to investigate the role of potential vaccine and drug targets in the pathogenesis of N. gonorrhoeae. It seems that the efforts for proposing novel vaccines and drug targets appear to be paving the way for a prevention-treatment strategy against this bacterium. Additionally, a combination of bactericidal monoclonal antibodies and antibiotics is a promising approach to curing N. gonorrhoeae.

Development of a High Sensitive Multiplex Lateral Flow Immunoassay (LFIA) System for Rapid Detection of Methicillin-Resistant Staphylococcus Aureus (MRSA).

Background: Methicillin-resistant Staphylococcus aureus (MRSA) has become a worldwide concern as an epidemic bacterium and a cause of nosocomial and community-acquired infections. One of the major problems in the prevention and treatment of infections caused by MRSA strains is their multi-drug resistant trait, which causes the spread of infections and increases the mortality rate. Therefore, a rapid and accurate method is needed to identify MRSA strains, initiate appropriate antibiotic therapy, and control its infection. The aim of this study was to develop a twin lateral flow immunoassay system to detect methicillin-resistant Staphylococcus aureus (MRSA). Methods: First, BSA blocked AuNPs-anti-peptidoglycan antibody and AuNPs-anti-BSA antibody were used to detect Staphylococcus aureus (S. aureus). Then, AuNPs-anti-PBP2a antibody was used to specifically detect MRSA. Sensitivity, specificity and limit of detection of this twin immunoassay system were assessed using MRSA, methicillin susceptible S. aureus and clinical samples. Results were compared to those of cefoxitin disc diffusion (FOX30) and Polymerase Chain Reaction (PCR) as gold standards. Results: The Limit of Detection (LOD) of this twin system were 103 and 104 CFU/ml for the first and second strips, respectively. Sensitivity and specificity of this innovative assay in detecting MRSA were 92.30 and 97.36%, compared to FOX30 and PCR, respectively. Conclusion: High rates of sensitivity and specificity of this initiative system show its high potentials for rapid and accurate detection of MRSA.

Multilocus VNTR analysis-ompA typing of Chlamydia trachomatis isolates in Tehran, Iran.

INTRODUCTION: This study is the first to describe the genetic diversity of C. trachomatis strains derived from patients with signs and symptoms of genitourinary infections admitted to Tehran health centers and hospitals using the high-resolution genotyping method, multilocus variable-number tandem-repeat analysis with ompA sequencing (MLVA)-ompA. METHODS: One hundred and sixty-seven urogenital specimens were collected from October 2019 to July 2020. Specimens were inoculated to cell culture and examined for the presence of C. trachomatis isolates by microscopic valuation. Out of 167 samples, 19 (11.3%) viable C. trachomatis organisms were isolated in cell culture. Eighteen isolates were successfully genotyped by MLVA-ompA analysis. RESULTS: The most prevalent ompA genotypes were E, D, F and G, comprising 42%, 26.3% and 21% and 10.5% of isolates, respectively. Other genotypes were not detected from any of the samples. Out of the 18 fully genotyped isolates, 10 different MLVA-ompA genotypes were obtained. The most prevalent MLVA-ompA genotypes were 8.6.1-E (33.3%) and 8.5.2-D (16.6%). Genotype 8.6.1-E was common in both females and males. CONCLUSIONS: Our results showed that MLVA-ompA analysis was more discriminatory than ompA typing alone and, therefore, a suitable complement to ompA. Using this method, dominant genotypes in the community and transmission patterns in sexual networks could be identified. The high diversity of C. trachomatis strains in Tehran may be due to the low level of public health and awareness, and future studies are needed.

Serotype Distribution and Multi Locus Sequence Type (MLST) of Erythromycin-Resistant Streptococcus Pneumoniae Isolates in Tehran, Iran.

Background: The number of erythromycin-resistant Streptococcus pneumoniae has significantly increased around the world. The present study aimed to determine the serotype distribution and molecular epidemiology of the erythromycin-resistant Streptococcus pneumoniae (ERSP) isolated from patients with invasive disease. Methods: A total of 44 Streptococcus pneumoniae isolates were tested for susceptibility to several antimicrobial agents. Additionally, the polymerase chain reaction (PCR) was applied to evaluate ERSP isolates in terms of the presence of erythromycin resistance genes (e.g., ermB and mefA). The isolates were serotyped using the sequential multiplex-PCR method, and molecular epidemiology was assessed through the multilocus sequence typing (MLST) analysis. Results: The results represented multidrug resistance (MDR) in approximately half of the pneumococcal isolates. Among 22 ERSP isolates, 20 (90.9%) and 12 (56%) ones contained ermB and mefA, respectively. Further, 14 (31.8%), 3 (22.7%), and 19A (18.1%) were the common serotypes among the isolates. No significant correlation was observed between serotypes and erythromycin resistance genes. Furthermore, the MLST results revealed 18 different sequence types (STs), the top ones of which were ST3130 (3 isolates) and ST166 (3 isolates). Population genetic analysis disclosed that CC63 (32%), CC156 (18%), and CC320 (18%) were identified as the predominant clonal complexes. Conclusions: The ERSP isolates exhibited high genetic diversity. The large frequency of MDR isolates suggests the emergence of high resistant strains, as well as the need to implement vaccination in the immunization schedule of Iran. These accumulating evidences indicate that 13-valent pneumococcal conjugate vaccines provided higher serotype coverage in the ERSP isolates.

Alteration of the Inflammatory and Anti-Inflammatory Cytokine Profiles of Peripheral Blood Mononuclear Cell in Crohn's Disease Patients after Following up.

Background: Crohn's disease (CD) has a chronic course, which its recurrence varies widely among different patients. In this study we prospectively analyzed blood samples of 19 CD patients. Alteration in transcription of inflammatory and anti-inflammatory cytokines was analyzed compared with household members after three month follow up. Methods: CD patients were diagnosed based on clinical symptoms, endoscopic and histopathologic characteristics. Nineteen CD patients and their households were evaluated from Jun 2019 to Feb 2021 at Tehran university hospitals. CD activity score, biological, clinical and demographic data of the patients were recorded at two time point intervals. Bacteriological tests were done using aerobic and anaerobic blood cultures. To investigate transcriptional alterations, peripheral blood mononuclear cells (PBMCs) were isolated using Ficol centrifugation method and relative quantitative real-time PCR was done to determine the expression level of IFN-γ, TNF-α, IL10, and FOXP3 cytokines. Results: Our results showed a correlation between fecal calprotectin level (709.8 ± 554.6), C-reactive protein concentration (18.1 ± 15.9), and erythrocyte sedimentation rate (30.4 ± 17.9) with disease activity (Flare/remission). IL10 and Foxp3 anti-inflammatory gene's expression were significantly (P = 0.003 for IL10 and P = 0.008 Foxp3) higher during the flare and remission in patients with active disease respectively. Bacteriological examination showed infection with Streptococcus spp. and Clostridium spp. in two CD patients during flares, which was correlated with upregulation and down-regulation of IL10, TNF-α, IFN-γ and FOXP3 proteins, respectively. Conclusion: Occurrence of bacteremia, and higher amount of CAP, CRP and ESR are correlated with higher level of transcription for inflammatory cytokines, which could effectively reflect the disease activity. Raise in FoxP3 transcription proposed change in Treg sub-population in PBMC or its activity during the CD remission phase.

Preparation of Photocatalytic TiO2-Polyacrylonitrile Nanofibers for Filtration of Airborne Microorganisms.

Background: We aimed to investigate the efficiency of neat polyacrylonitrile (PAN) nanofibers and photocatalytic PAN/TiO2 nanofibers for removal of airborne microorganisms. Methods: Nanofibers were fabricated from 16 wt% of PAN dissolved in dimethyl formamide through the electrospinning technique. The efficiency of media for removal of Staphylococcus epidermidis and Bacillus subtilis was investigated at different conditions such as face velocity, relative humidity, air temperature and UVC radiation intensity. as face velocity (0.1 and 0.3 m/s), relative humidity (35±5% and 60±5%), air temperature (22±3 °C and 30±3 °C) and the UVC radiation intensity (dark, 1±0.09 mW/cm2 and 1.8±0.07 mW/cm2) using air sampling from upstream and downstream of media by cascade impactor containing blood agar culture medium. Results: The mean diameter of electrospun fibers and coefficient of variation were 194 nm and 15%, respectively. The amount of immobilized TiO2 on the filter was 620±6.56 mg/m2. Photocatalytic nanofiber filter media presented the best performance for removal of airborne B. subtilis at 60±5% relative humidity, 0.1 m/s face velocity, air temperature 22 °C, and 1.8 ± 0.07 mW/cm2 UVC radiation. Conclusion: The filtration efficiency of photocatalytic media was significantly higher than neat ones. Lower efficiency of media was found in the higher air velocity for all bioaerosols. High UVC radiation intensity increased filtration efficiency. Moreover, the increase in air temperature and relative humidity (except for TiO2-coated media under UVC radiation) did not significantly affect the filtration efficiency of all media.

A novel shiga based immunotoxin against Fn-14 receptor on colorectal and lung cancer.

Immunotoxins are regarded as a type of targeted therapy for killing cells by highly potent bacterial, fungal or plant toxins. Shiga like toxins (SLTs) are a group of bacterial AB5 protein toxins that inhibit host cell protein synthesis through the removal of a single adenine residue from the 28S rRNA and lead to apoptosis. Here, we described the design and usage of a Stx-based immunotoxin that can induce the selective cytotoxicity and apoptosis in Fn-14-positive cells related to the colon and lung cancer. In the present study, the Stx2a-PE15-P4A8 fusion protein was expressed efficiently in E. coli (DE3) system when driven from inclusion bodies by 8 M urea. The Stx2a-PE15-P4A8 fusion protein was expressed efficiently in E. coli (DE3) system and then purified. The purified fusion protein could specifically target Fn-14 receptor existed on colon and lung cancer cell lines and suppress these cells in a dose-dependent manner. In addition, the protein was able to nearly 50 % of apoptotic cell death and maintains about 54 % of its stability after 24 h of incubation in mouse serum at 37 °C. Compared to PE38-P4A8 construct in our previous study, these results showed that the Stx2a-PE15-P4A8 construct can be an efficient therapeutic candidate for cancer immunotherapy.

The effects of Chlamydia trachomatis, Mycoplasma hominis, and Ureaplasma urealyticum loads on semen quality: Detection and quantitative analysis.

BACKGROUND: The loads of Chlamydia trachomatis (CT), Mycoplasma hominis (MH), and Ureaplasma urealyticum (UU) may impact infertility, as well as cause risk of transmission. The quality and quantity of semen demonstrate male reproductive health. This study aimed to investigate the semen quality affected by CT, MH, and UU loads. MATERIALS AND METHODS: 130 semen samples, including infertile and fertile cases, were collected and analyzed. The whole genomic DNA was extracted, and the desired genes' plasmids were constructed. The CT, MH, and UU loads were quantified by real-time PCR. The data were analyzed using SPSS version 24. RESULTS: The average age of participants was 35.2 ± 6.8 years. CT, MH, and UU frequency were 9.2% vs. 3.1%, 15.4% vs. 3.1%, and 15.4 vs. 3.1% in infertile and fertile men, respectively. The mean loads of CT, MH, and UU in infertile men were 6.44 log10 copies/ml (range 5.31-7), 4.24 log10 copies/ml (range 3.37-4.7), and 6.94 log10 copies/ml (range 5.08-8.69) respectively, which was significantly higher than fertile men. The findings revealed a significant correlation between CT and UU loads and semen parameters, whereas the load of MH displayed significant effects just on sperm motility, morphology, and the number of leukocytes. CONCLUSION: The absence of clinical manifestations may not indicate the quality of semen. The pathogens' loads may significantly influence the quality and properties of male reproductive health.

Identification and molecular characterization of penicillin-nonsusceptible Streptococcus pneumoniae isolates recovered from invasive infections in a pre-pneumococcal vaccine era.

BACKGROUND: Given the significant role of penicillin-nonsusceptible Streptococcus pneumoniae in inducing severe infectious diseases, identifying serotypes and genotypes that can mediate antimicrobial resistance has become a pillar of treatment strategies. This study aims to determine the correlation between the minimum inhibitory concentration of antimicrobial agents and amino acid mutations in penicillin-binding proteins. Moreover, molecular serotyping and multiple-locus variable number tandem repeat analysis typing were first-ever performed to characterize the invasive penicillin-nonsusceptible S. pneumoniae isolates in Iran. METHODS: Of 149 isolates, antimicrobial susceptibility tests were performed against penicillin, ceftriaxone, and cefotaxime by the MIC Test Strip, and sequence analysis of the pbp genes was performed through PCR-sequencing method. All penicillin-nonsusceptible S. pneumoniae isolates were serotyped and genotyped by sequential multiplex PCR and multiple-locus variable-number tandem repeat analysis, respectively. RESULTS: Among pneumococcal isolates, 53 isolates were classified as penicillin-nonsusceptible S. pneumoniae, of which 38 (71.7%) and 15 (28.3%) were resistant and intermediate to penicillin, respectively. Furthermore, ceftriaxone- and cefotaxime-nonsusceptible pneumococci constituted 33 (62.2%) and 29 cases (54.7%), respectively. Of note, there were 8 and 41 different serotypes and multiple-locus variable-number tandem repeat analysis types, respectively. CONCLUSIONS: Due to the increasing resistance to antimicrobial agents, the most efficient approach to preventing pneumococcal infection mortality as vaccine-preventable diseases is focusing on wide-spectrum vaccination. Based on our findings, the 13-valent pneumococcal conjugate vaccine could considerably reduce the incidence of invasive pneumococcal diseases due to the high rate of serotype coverage.

Antimicrobial susceptibility testing and molecular characterization of Neisseria gonorrhoeae in Tehran, Iran.

Gonorrhea is a sexually transmitted infection occurring worldwide. Antimicrobial resistance (AMR) surveillance in Neisseria gonorrhoeae and associated molecular epidemiological studies are crucial to ascertain the spread of antibiotic-resistant and developing the local treatment guidelines. This study was performed to determine the antimicrobial susceptibility testing (AST) and molecular epidemiology of N. gonorrhoeae isolates in Tehran, Iran. During 1 July 2018-30 July 2020, a total of 500 urogenital (468 endocervical, 32 urethral) swabs were collected from patients with signs and symptoms of genitourinary infections presenting to two women's hospitals and one health center located center and south of Tehran. Specimens were cultured and examined for the presence of N. gonorrhoeae isolates by biochemical tests. MIC Test Strip determined the MICs of ceftriaxone, azithromycin, and ciprofloxacin. Neisseria gonorrhoeae multiantigen sequence typing (NG-MAST) was also performed. A total of 38 N. gonorrhoeae isolates were identified. The proportions of resistant N. gonorrhoeae isolates were as follows: ceftriaxone (MIC ≥0.125 µg/mL) 10.5% (4/38), azithromycin (MIC >1 µg/mL) 34% (13/38), and ciprofloxacin (MIC ≥1 µg/mL) 31.5% (12/38). In total, 25 different NG-MAST STs were identified. The STs comprised 1-4 isolates each, and the predominant ST was ST266 (n = 4). Our study demonstrates a diverse gonococcal population with high rates of resistance to azithromycin and evidence of resistance to ceftriaxone. The results have potential implications for antibiotic choice for the gonococcal treatment and highlight the need to broaden gonococcal AMR monitoring in Iran.

Investigation of novel putative immunogenic targets against Staphylococcus aureus using a reverse vaccinology strategy.

BACKGROUND: The emergence of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant S. aureus (VRSA) strains is a significant public health concern. Considering the high morbidity and mortality of invasive S. aureus infections and multi-drug resistant strains, there is an urgent need for non-antibiotic immune-based approaches to cure these infections. Despite all efforts, vaccine candidates targeting S. aureus failed in human clinical trials, and no approved vaccine is available against this pathogen. Therefore, this study aimed to introduce suitable candidates for immunization against S. aureus using a comprehensive reverse vaccinology approach. METHODS: In this study, we retrieved putative immunogenic targets from three different levels (literature review, automated reverse vaccinology, and manual reverse vaccinology) and evaluated them using several immunoinformatics analyses including antigenicity, allergenicity, PSI-BLAST to human proteome, physiochemical properties, B-cell, and T-cell epitopes. In the next step, the quartile method scoring was used to the shortlisted proteins. Finally, the molecular docking and immune simulation of immunogenic targets were performed. RESULTS: This study presents 12 vaccine candidates, including three enzymatic proteins (WP_000222271.1, WP_001170274, and WP_000827736.1), three cell wall-associated proteins (WP_001125631.1, WP_000731642, and WP_000751265.1), two hemolysins (WP_000594517.1, and WP_000916697.1), one secretion involved protein (WP_000725226.1), one heme­iron binding protein (WP_001041573.1), one superantigen like protein (WP_000668994.1) and one hypothetical proteins (WP_000737711.1). CONCLUSION: Through quartile scoring method, immune simulation and molecular docking, four promising targets including lytic transglycosylase IsaA, HlgA, secretory antigen precursor SsaA, and heme uptake protein IsdB were selected as the shortlisted proteins. It seems that a polarized immunization (Th1/Th17) response is needed for protection against this bacterium. An optimized formulation based on these putative immunogenic proteins and a wisely adjuvant selection may drive the immune system toward a full protection.

Expression of type II toxin-antitoxin systems and ClpP protease of methicillin-resistant Staphylococcus aureus under thermal and oxidative stress conditions.

BACKGROUND AND OBJECTIVES: Staphylococcus aureus is a main human pathogen that causes a variety of chronic to persistent infections. Across the diverse factors of pathogenesis in bacteria, Toxin-Antitoxin (TA) systems can be considered as an anti-bacterial target due to their involvement in cellular physiology counting stress responses. Here, the expression of TA system genes and ClpP protease was investigated under the thermal and oxidative conditions in S. aureus strains. MATERIALS AND METHODS: The colony-forming unit (CFU) was used to determine the effects of thermal and oxidative stresses on bacterial survival. Moreover, the expressions of TA system genes in S. aureus strains were evaluated 30 min and 1 h after thermal and oxidative stresses, respectively, by quantitative reverse transcriptase real-time PCR (qRT-PCR). RESULTS: The cell viability was constant across thermal stress while oxidative stress induction showed a significantly decrease in the growth of Methicillin-Resistant S. aureus (MRSA) strain. Based on the qRT-PCR results, the expression of mazF gene increased under both thermal and oxidative stresses in the MRSA strain. CONCLUSION: A putative TA system (namely immA/irrA) most likely has a role under the stress condition of S. aureus. The MRSA strain responds to stress by shifting the expression level of TA genes that has diverse effects on the survival of the pathogen due to the stress conditions. The TA systems may be introduced as potential targets for antibacterial treatment.

Antibiotic tolerance in biofilm persister cells of Staphylococcus aureus and expression of toxin-antitoxin system genes.

The ability of Staphylococcus aureus to form biofilm and persister cells is the main cause of recurrent infections. This study aimed to evaluate the expression of toxin-antitoxin (TA) systems in persister cells within S. aureus biofilms. Time-dependent variation in the persister population present in biofilms of S. aureus was examined after treatment with bactericidal antibiotics. Then, the relative expression level of type II TA system (mazF, relE1, and relE2), type I TA system (sprG), and clpP protease genes in S. aureus strains were assessed by Real _Time PCR. Among the sixteen isolates, two isolates were found to be the strongest biofilm producers. The established biofilm of these isolates showed a comparable biphasic pattern at the lethal dose of the antibiotics. The expression level of TA system genes was increased and strain-specific expression patterns were observed under antibiotics stress conditions. Persisters within a biofilm may establish a reservoir for relapsing infection and could contribute to treatment failures. Hence, the possible role of the TA systems should be considered in biofilm and persister cell formation.

Antimicrobial Susceptibility, Serotyping, and Molecular Characterization of Antibiotic Resistance Genes in Listeria monocytogenes Isolated from Pregnant Women with a History of Abortion.

BACKGROUND: Listeria monocytogenes show high mortality among pregnant women and newborns. This study aimed to detect L. monocytogenes in pregnant women with a history of abortion and assess the serotypes, antibiotic susceptibility patterns, and its resistance genes. METHODS: Overall, 400 vaginal swabs were taken from pregnant women with a history of abortion in the past few years in a tertiary care hospital in Tehran, Iran, during 2015-2018. Antibiotics susceptibility to a panel of 10 antibiotics was determined using the standard disk diffusion method and the isolates serotyped by the agglutination method. The antimicrobial-resistant isolates were also screened for the presence of tetM, ermB and dfrD genes by PCR. RESULTS: Overall, 22 L. monocytogenes isolates were identified. High rates of resistance were observed for trimethoprim (50%; n=11), sulphamethoxazole (50%; n=11), tetracycline (45.45%; n=10) and gentamicin (36.36%; n=8). From 22 L. monocytogenes isolates, 13 (59.10 %), 5 (22.73%), 3 (13.63%) and 1 (4.54%) belonged to serotypes 4b, 1/2a, 1/2b, and 3c, respectively. The genetic determinant tetM was detected in 70% of the tetracycline-resistant isolates. Out of 11 trimethoprim-resistant isolates, 27.27% isolates contained dfrD. Moreover, the ermB gene was found in 83.33% of the erythromycin-resistant isolates. CONCLUSION: Ampicillin and partly penicillin consider to be suitable antimicrobial agents to treat human listeriosis. Moreover, due to resistance against many antibiotics, it is necessary to continue monitoring and managing antimicrobial resistance.

Redox imbalance in Crohn's disease patients is modulated by Azathioprine.

BACKGROUND: Crohn's disease (CD) is a chronic inflammatory disease without a specific cause. Inflammation in these patients can disturb the oxidants/antioxidants balance and results in oxidative stress that plays a destructive role. This study aimed to evaluate the gene expression of sod1, sod2, cat, nrf2 and gp91phox in CD patients before and after Azathioprine (Aza) consumption. METHOD: Peripheral bloodmononuclear cells (PBMCs) were separated from CD patients (n= 15, mean age = 33.6 ± 1.8) before and after treatment with Aza and healthy controls (n= 15, mean age = 31.5 ± 1.2). The expression levels of sod1, sod2, cat, nrf2 and gp91phox were measured in byusing real-time qRT-PCR technique. RESULT: The expression levels of gp91phox (P-value < 0.001), cat (P-value < 0.05), sod1 (P-value < 0.001), nrf2 (P-value < 0.001) were significantly increased compared to control group. Following treatment with Aza, the decreased expression levels of gp91phox (P-value < 0.05), cat (P-value < 0.05), sod1(P-value < 0.001) and nrf2 (P-value < 0.001) were observed in CD patients. CONCLUSION: Overall, our results showed that prescription of Azathioprine can lead to the altered expression of redox system-related genes in patients with CD.

Detection and characterization of Enterobacteriaceae family members carried by commensal Rattus norvegicus from Tehran, Iran.

Wild rats are known to carry different microorganisms and are considered a reservoir of zoonotic pathogens worldwide. The urban rats were collected from five districts of Tehran and Gram-negative bacteria (GNB) were isolated from fecal samples and were identified using classical biochemical tests. The antibiotic susceptibility patterns of isolated bacteria were determined by Kirby-Bauer disk diffusion method, the results of which were interpreted in line with CLSI guideline. The frequency of antibiotic-resistant genes was identified using multiplex-PCR. Moreover, PCR method was used to identify the frequency of Escherichia coli O157:H7 and main categories of diarrheagenic E. coli including EPEC, ETEC, EIEC, EAEC, and STEC pathotypes. A total of 100 Rattus norvegicus were trapped and fecal samples were collected. Overall, 72 fecal samples were positive for GNB. E. coli (n = 46/72) had the highest frequency among the isolated GNB. Among E. coli isolates, the highest and lowest resistance rates belonged to ampicillin (56.5%) and ceftriaxone (0%), respectively. Klebsiella spp. was 100% resistant to imipenem, and streptomycin (0%) was the most effective antimicrobial agent on Klebsiella spp. Among surveyed genes, blaTEM (95.8%) and blaaadA-1 (58.3%) had the highest frequency, while blaKPC, and blaCMY-2 were not detected among Enterobacteriaceae. Herein, O157: H7 serotype was not detected and aEPEC (87%) was the most common pathotype detected. Results suggested that rodents might be a reservoir of antimicrobial-resistant pathogens and rodent control along with implementation of surveillance programs should be considered as a critical priority for urban health.