GNAT toxin may have a potential role in Pseudomonas aeruginosa persistence: an in vitro and in silico study.

Aims: Persistent cells are primarily responsible for developing antibiotic resistance and the recurrence of Pseudomonas aeruginosa. This study investigated the possible role of GNAT toxin in persistence. Materials & methods: P. aeruginosa was exposed to five MIC concentrations of ciprofloxacin. The expression levels of target genes were assessed. The GNAT/HTH system was bioinformatically studied, and an inhibitory peptide was designed to disrupt this system. Results: Ciprofloxacin can induce bacterial persistence. There was a significant increase in the expression of the GNAT toxin during the persistence state. A structural study of the GNAT/HTH system determined that an inhibitory peptide could be designed to block this system effectively. Conclusion: The GNAT/HTH system shows promise as a novel therapeutic target for combating P. aeruginosa infections.

Antibiotics are used to treat infections caused by bacteria. Over time, some of these infections have become more difficult to treat. This is because the bacteria can slow their growth and tolerate the antibiotic, known as persistence. It is important to find new ways to treat infections caused by persistent bacteria. This study researched a toxin­antitoxin system, called GNAT/HTH, that may play a role in bacterial persistence. This system could be a target for new antibiotics.

Effect of ZnO nanoparticles on biofilm formation and gene expression of the toxin-antitoxin system in clinical isolates of Pseudomonas aeruginosa.

BACKGROUND: Biofilm formation by Pseudomonas aeruginosa (P. aeruginosa) is known to be characteristic of this organism. This bacterium is considered one of the most life-threatening bacteria and has been identified as a priority pathogen for research by WHO. Biofilm-producing P. aeruginosa is a concern in many parts of the world due to antibiotic resistance. Alginate also plays an important role in the biofilm formation of P. aeruginosa as well as the emergence of antibiotic resistance in biofilms. In addition, the systems of toxin-antitoxin( TA) play an important role in biofilm formation. Metal nanoparticle(NP) such as zinc oxide (ZnO) also have extensive biological properties, especially anti-biofilm properties. Therefore, this study was conducted in relation to the importance of zinc oxide nanoparticles (ZnO NPs) in biofilm formation and also the correlation of gene expression of TA systems in clinical isolates of P. aeruginosa. METHODS: A total of 52 P. aeruginosa isolates were collected from burns (n = 15), UTI (n = 31), and trachea (n = 6) in hospitals in Ilam between May 2020 and October 2020. Biofilm formation was assessed using a microtiter plate assay. MIC and sub-MIC concentrations of ZnO NPs (10-30 nm with purity greater than 99.8%) in P. aeruginosa were determined. Subsequently, biofilm formation was investigated using sub-MIC concentrations of ZnO NPs. Finally, total RNA was extracted and RT- qPCR was used to determine the expression levels of genes of mazEF, mqsRA, and higBA of TA systems. RESULTS: Six isolates of P. aeruginosa were found to form strong biofilms. The results showed that ZnO NPs were able to inhibit biofilm formation. In our experiments, we found that the sub-MIC concentration of ZnO NPs increased the gene expression of antitoxins mazE and mqsA and toxin higB of TA systems treated with ZnO NPs. CONCLUSIONS: In the present study, ZnO NPs were shown to effectively inhibit biofilm formation in P. aeruginosa. Our results support the relationship between TA systems and ZnO NPs in biofilm formation in P. aeruginosa. Importantly, the expression of antitoxins mazE and mqsA was high after treatment with ZnO NPs, but not that of antitoxin higA.

In vitro anti-biofilm properties of the peel of fruite wall of acorn against Streptococcus mutans.

Dental caries is a multi-factorial infectious disease. The primary cause is dental plaque, a complex of biofilm. It was postulated that the ethanolic extract of fruite wall of acorn may represent a new substance to prevent caries. Hence, the study was performed to evaluate the effect of ethanolic extract of fruite wall of acorn against biofilm formation by Streptococcus mutans, which is associated with dental plaque. The cytotoxicity of the ethanolic extract was determined against Vero cells resulting in an inhibitory concentration of 50 (IC50) of 55 µg/ml. After bacterial collection, different concentrations under the IC50 from the extract were evaluated against biofilm formation of S. mutans. 3 µg/ml of the extract inhibited the biofilm formation of S. mutans, and 1 to 3 µg/ml caused a decrease in gtfB and brpA biofilm-production genes. This study showed the potency of the ethanolic extract of fruite wall of acorn against biofilm formation by S. mutans.

Molecular characterizations of antibiotic resistance, biofilm formation, and virulence determinants of Pseudomonas aeruginosa isolated from burn wound infection.

BACKGROUND: Burn injuries result in disruption of the skin barrier against opportunistic infections. Pseudomonas aeruginosa is one of the main infectious agents colonizing burn wounds and making severe infections. Biofilm production and other virulence factors along with antibiotic resistance limit appropriate treatment options and time. MATERIALS AND METHODS: Wound samples were collected from hospitalized burn patients. P. aeruginosa isolates and related virulence factors identified by the standard biochemical and molecular methods. Antibiotic resistance patterns were determined by the disc diffusion method and ß-lactamase genes were detected by polymerase chain reaction (PCR) assay. To determine the genetic relatedness amongst the isolates, enterobacterial repetitive intergenic consensus (ERIC)-PCR was also performed. RESULTS: Forty P. aeruginosa isolates were identified. All of these isolates were biofilm producers. Carbapenem resistance was detected in 40% of the isolates, and blaTEM (37/5%), blaVIM (30%), and blaCTX-M (20%) were the most common ß-lactamase genes. The highest resistance was detected to cefotaxime, ceftazidime, meropenem, imipenem and piperacillin, and 16 (40%) isolates were resistant to these antibiotics. The minimum inhibitory concentrations (MIC) of colistin was lower than 2 µg/mL and no resistance was observed. Isolates were categorized to 17 MDR, 13 mono-drug resistance, and 10 susceptible isolates. High genetic diversity was also observed among the isolates (28 ERIC types) and most carbapenem-resistant isolates were classified into four main types. CONCLUSION: Antibiotic resistance, particularly carbapenem resistance was considerable among the P. aeruginosa isolates colonizing burn wounds. Combining carbapenem resistance with biofilm production and virulence factors would result in severe and difficult-to-treat infections.

Development of innovative multi-epitope mRNA vaccine against Pseudomonas aeruginosa using in silico approaches.

The rising issue of antibiotic resistance has made treating Pseudomonas aeruginosa infections increasingly challenging. Therefore, vaccines have emerged as a viable alternative to antibiotics for preventing P. aeruginosa infections in susceptible individuals. With its superior accuracy, high efficiency in stimulating cellular and humoral immune responses, and low cost, mRNA vaccine technology is quickly replacing traditional methods. This study aimed to design a novel mRNA vaccine by using in silico approaches against P. aeruginosa. The research team identified five surface and antigenic proteins and selected their appropriate epitopes with immunoinformatic tools. These epitopes were then examined for toxicity, allergenicity and homology. The researchers also checked their presentation and identification by major histocompatibility complex cells and other immune cells through valuable tools like molecular docking. They subsequently modeled a multi-epitope protein and optimized it. The mRNA was analyzed in terms of structure and stability, after which the immune system's response against the new vaccine was simulated. The results indicated that the designed mRNA construct could be an effective and promising vaccine that requires laboratory and clinical trials.

In Vitro and In Silico Investigation of some Type II TA Genes in H. Pylori.

BACKGROUND: In addition to antibiotic resistance, the entry of Helicobacter pylori into the persistence phase leads to recurrent and chronic infections, as well as the development of antibiotic resistance in persister cells. METHODS: In this study, after genetic confirmation of H. pylori in 20 biopsy specimens, the prevalence of the type II TA systems mazEF, relEB, yafQ/dinJ was investigated. Also, the most common system observed in the study in terms of structure, evolution, and molecular interaction was evaluated by bioinformatics tools. RESULTS: The results of the PCR test on 20 biopsy samples were positive for ureA and glmM genes. Moreover, yafQ/ dinJ was the only module positive in half of the samples (10 samples) in the PCR technique. The toxin residues and their interactions with the cognate antitoxin residues are revealed by docking analysis results. Furthermore, the multiple sequence alignment (MSA) of the YafQ toxin showed that this toxin has a low polymorphism among H. pylori species. The evolutionary study showed that the yafQ toxin had the highest sequence similarity among the bacteria Helicobacter cetorm (60% similarity) and Muricauda olearia (57.35 % similarity). CONCLUSIONS: Collectively, the data of the present study indicate that the YafQ/DinJ is the dominant type II TA system and has the highest frequency among the studied systems in H. pylori, and further studies are required to elucidate its exact role in this bacterium.

Economic evaluation of laboratory diagnostic test types in Covid-19 epidemic: A systematic review.

BACKGROUND: Corona 2 virus (SARS-CoV-2) is known as the causative agent of COVID-19 disease; the World Health Organization (WHO) declared it an epidemic on March 11, 2020. The Joint Guidelines of the Centers for Disease Control and Prevention (CDC) and the WHO including social distancing, the use of face masks, emphasis on hand washing, quarantine, and using diagnosis tests have been used widely, but the value of diagnostic interventions to prevent the transmission of SARS-CoV-2 is unclear. We compared the economic evaluation of different laboratory diagnostic interventions with each other and also with implementing the conservative CDC & WHO guidelines. MATERIAL AND METHODS: Electronic searches were conducted on PubMed, Embase, Science Direct, Scopus, Cochrane Library, Web of Knowledge, NHSEED, NHS Health Technology assessment (CRD), and Cost-Effectiveness Analysis Registry databases. Related articles were reviewed from January 2020 to the end of November 2021. RESULTS: Out of 1791 initial studies, 13 articles had the inclusion criteria. According to the Consolidated Health Economic Evaluation Reporting Standards (CHEERS) checklist, ten studies were of excellent quality, and the remaining two studies were of very good quality. Most studies were cost-effectiveness analysis studies. The entered studies had different time horizons. Diagnostic tests reviewed in the studies included real-time polymerase chain reaction (RT-PCR) test, immunoglobulin G (IgG) & Antigen, point of care tests. Although polymerase chain reaction (PCR) testing improves the quality of life and survival for patients with infected Covid-19 based on its greater effectiveness compared to standard protection protocols, due to the high cost of this intervention, it has been considered a cost-effective method in some countries. CONCLUSION: Since most studies have been conducted in developed countries, it unquestionably does not make sense to extend these results to low-income and developing countries. Therefore further studies are required in low-income and developing countries to evaluate the cost-effectiveness of laboratory-based diagnostic methods (RT-PCR) of covid-19 in variable prevalence of infectious cases.

The prevalence of gonococcal and non-gonococcal infections in women referred to obstetrics and gynecology clinics.

Bacterial vaginosis is a condition caused by changes in the vaginal microbial ecosystem and increases the risk of preterm delivery, premature rupture of membranes, endometritis, and weight loss of the baby. This study aimed to evaluate the frequency of gonococcal and non-gonococcal genital infections in women referred to clinics in Ilam, Iran. Two swab samples were taken from each patient using a sterile swab, one swab was placed in a THB medium for the culture of Streptococcus agalactiae and the other in PBS buffer for PCR. PCR method was conducted for the identification of the other bacterial agents such as Neisseria gonorrhoeae, Chlamydia trachomatis, Mycoplasma genitalium, Mycoplasma hominis, Ureaplasma urealyticum, and also S. agalactiae. Sampling was performed on 169 women with symptomatic vaginosis. The frequency of S. agalactiae by culture and PCR methods was 4.7% (8 samples) and 13.6% (23 samples) respectively. Also, 6.5% (11 samples), 3.5% (6 samples), 4.1% (7 samples), 1.2% (2 samples), and 0% of the samples were positive for N. gonorrhoeae, M. genitalium, M. hominis, U. urealyticum and C. trachomatis by PCR method. Except for a significant association between S. agalactiae colonization and abortion, there was no significant correlation between the prevalence of these bacteria and the patient's age, age of marriage, number of deliveries, and number of abortions. Overall, the prevalence of gonococcal and non-gonococcal infection in women referred to clinics in Ilam is similar to the other parts of Iran.

Novel Antimicrobial Target in Acinetobacter Baumannii.

BACKGROUND: Resistance to multiple drugs is one of the biggest challenges in managing infectious diseases. Acinetobacter baumannii is considered a nosocomial infection. According to the multiple roles of the toxin-antitoxin system, this system can be considered an antimicrobial target in the presence of bacteria. With the impact on bacterial toxin, it can be used as a new antibacterial target. The purpose of this study was to determine the mazEF genes as a potent antimicrobial target in A. baumannii clinical isolates. METHODS: The functionality of mazEF genes was evaluated by qPCR in fifteen A. baumannii clinical isolates. Then, the mazE locus was targeted by peptide nucleic acid (PNA). RESULTS: The results showed a significant difference in the mean number of copies of mazF gene in normal and stress conditions. Also, we found that at a concentration of 15 µM of PNA the bacteria were killed and confirmed by culture on LB agar. CONCLUSIONS: This research is the first step in introducing mazEF TA loci as a sensitive target in A. baumannii. However, more studies are needed to test the effectiveness in vivo. In addition, the occurrence and potential for activation of the TA system, mazEF in other pathogenic bacteria should be further investigated.

Heteroresistance to clarithromycin and metronidazole in patients with a Helicobacter pylori infection: a systematic review and meta-analysis.

BACKGROUND: Antimicrobial resistance of H. pylori can lead to treatment failure. Importantly, several studies have reported on heteroresistance, i.e. the presence of resistant and susceptible H. pylori populations in the same sample and/or a difference in the susceptibility patterns between biopsy samples. This meta-analysis aims to provide comprehensive data on the prevalence of metronidazole and clarithromycin heteroresistance and the approaches to their detection. MATERIAL AND METHODS: A systematic review was performed after the search of MEDLINE, Scopus and Web of Science. The study outcomes were the weighted pooled prevalence of heteroresistance to clarithromycin and metronidazole in H. pylori positive samples and/or isolates with a subanalysis by continent. RESULTS: A total of 22 studies that had investigated 3852 H. pylori positive patients were included in the meta-analysis. Heteroresistance to clarithromycin was reported in 20 studies, with a weighted pooled prevalence of 6.8% (95% CI 5.1-8.6; 3654 H. pylori positive patients; the substantial heterogeneity I2 = 55.6%). Heteroresistance to metronidazole was reported in 12 studies, with a weighted pooled prevalence of 13.8% (95% CI 8.9-18.6; 1670 H. pylori positive patients; the substantial heterogeneity I2 = 60.9%). The weighted pooled prevalence of clarithromycin heteroresistance was similar in Asia and Europe (p = 0.174584), however, metronidazole heteroresistance was detected more often in Europe (p < 0.00001). Clarithromycin heteroresistance was detected more often by phenotype rather than by using genotyping methods (12 vs 8 studies), whereas heteroresistance to metronidazole was detected only by phenotype. CONCLUSION: The prevalence of heteroresistance to clarithromycin and/or metronidazole is not negligible and can be detected in approximately 7 and 14% of H. pylori positive samples, respectively. These findings highlight the need to raise the awareness of gastroenterologists and microbiologists to the heteroresistance to clarithromycin and metronidazole in patients with a H. pylori infection.

relBE toxin-antitoxin system as a reliable anti-biofilm target in Pseudomonas aeruginosa.

AIMS: The ability of the pathogenic bacterium Pseudomonas aeruginosa to produce biofilms has made it more difficult to treat its infections with current antibiotics. Several genes are involved in biofilm production, and toxin-antitoxin (TA) loci have been reported to be responsible for the regulation of biofilm-associated genes. This study was aimed at evaluating various TA loci in P. aeruginosa to find a reliable target in order to disrupt biofilm formation. METHODS AND RESULTS: Thirty clinical isolates of P. aeruginosa were assessed for biofilm production as well as the presence of various TA loci in their genomes. The relBETA locus was present in all 30 P. aeruginosa isolates but its expression was not detectable in isolates that did not show biofilm production. Quantitative real-time -PCR (q-PCR) also demonstrated that the expression of relBE was higher in isolates with stronger biofilm-producing capability. Knocking out the relBE locus in one biofilm-producing P. aeruginosa isolate led to the cessation of biofilm-producing capacity in that isolate and eliminated the expression of ndvB, which is among the genes involved in biofilm production. CONCLUSIONS: These results inferred the involvement of relBE TA locus in the regulation of biofilm production in P. aeruginosa and indicated the possibility of relBE as an anti-biofilm target for this pathogen.

Effect of Chlorhexidine (CHX) and Hydrogen Peroxide (H2O2) on the Biofilm Formation of Enterococcus faecalis.

BACKGROUND: Biofilm makes bacteria resistant to antimicrobial agents and facilitates the transmission of infectious diseases in hospitals. Disinfectant compounds are frequently used to control surface contamination. This study was designed to investigate the effect of chlorhexidine (CHX) and hydrogen peroxide (H2O2) on biofilm formation of Enterococcus faecalis. METHODS: This study was performed on 40 E. faecalis clinical isolates. After the determination of MIC, the effect of different concentrations of CHX and H2O2 on the biofilm formation was evaluated. Also, the relative expression level of the studied biofilm genes, following exposure to sublethal concentration of CHX and H2O2, was assessed using quantitative reverse transcription PCR (qRT-PCR). RESULTS: The frequency of the asa1, efaA, epaI, and esp biofilm genes were 80%, 92.5%, 100%, and 75%, respectively. Various concentrations of CHX increased the biofilm mass in E. faecalis. Also, the combination of CHX and H2O2 at sub-minimal inhibitory concentrations, significantly elevated the expression of asa1, epaI, and esp genes. CONCLUSIONS: The results of this study showed that the improper use of disinfectants can increase the ability of biofilm formation in E. faecalis and may cause selective pressure leading to the emergence of biocide-resistant microorganisms.

In vitro Eradication of Pseudomonas aeruginosa Persister Cell Producers by Peganum harmala.

BACKGROUND: Because of increasing antibiotic failure and recurrence of infections in patients with P. aeruginosa, the present study was designed to determine the antibiotic resistance status, presence of persister cells and investigate the antipersister effect of Peganum harmala in P. aeruginosa clinical isolates in vitro in Ilam, Iran. METHODS: Thirty P. aeruginosa urinary clinical isolates were collected from hospitals in Ilam, Iran and identified by common microbiological and biochemical tests. Afterward, antibiotic susceptibility assay, persister cell assay, P. harmala extraction, cell culture, and cell viability assays were performed. RESULTS: A high rate of antibiotic resistance was observed. All isolates were resistant to co-amoxiclav. Also, 83.3% (n = 25), 90% (n = 27), and 36.6% (n = 11) of isolates showed resistance to ceftazidime, kanamycin, and tobramycin, respectively. The MIC and MBC values for imipenem were ≤ 2 and 2 µg/mL for susceptible isolates, respectively. In addition, 6.66% (n = 2) of isolates were persister cells and were also sensitive to imipenem by MIC but did not show any MBC. IC50 for P. harmala was 35 µg/mL. Eventually, MIC value of P. harmala against two P. aeruginosa persister cell producer isolates was 3 µg/mL and 1 µg/mL, and the value of MBC was 10 µg/mL and 30 µl/mL. CONCLUSIONS: Our findings demonstrated that P. harmala may be a suitable antipersister herbal medicine against P. aeruginosa clinical isolates. In this regard, comprehensive research is needed in the future to gain more information in this area.

In silico Investigation of Lon Protease as a Promising Therapeutic Target.

Considering the widespread occurrence of antibiotic resistance, the need for new therapeutic strategies is inevitable. Bacterial proteases are a broad set of enzymes that play a vital role in cell survival, stress response, and pathogenicity. This in silico study was aimed to focus on the crucial role of Lon protease in the regulation of toxin-antitoxin systems in E. coli and to design inhibitory peptides against the action of this protease. With the help of relevant servers and softwares, the communication network, the evolutionary history, and the interaction of Lon with the corresponding antitoxins were examined, following which the inhibitory peptides were designed against these interactions. The results showed that Lon protease plays a central role in the control of these systems and is a conserved protein, especially among the Enterobacteriaceae family. The docking results of the designed peptides with the Lon protease were significant. This study showed that Lon protease may have the characteristics of a new therapeutic target.

Microbiological and drug resistance patterns of bronchoalveolar lavage samples taken from hospitalized patients in Iran.

Introduction: Pulmonary diseases are amongst the most common causes of premature death and distressing disorders worldwide. This study aimed to detect the fastidious and routine infectious agents, and their drug resistance patterns in bronchoalveolar lavage (BAL) samples. Methods: A total of 44 BAL samples were collected by bronchoscopy from patients with respiratory disorders hospitalized at 2 teaching hospitals in Ilam, Iran. The samples were cultured on routine bacterial culture media to identify the bacterial agents and calculate the colony count. Antibiotic susceptibility was determined by disk diffusion method according to the CLSI protocol. PCR was used to detect the fastidious bacteria Mycoplasma pneumoniae and Chlamydia pneumoniae using the 16srRNA specific primers and Legionella pneumophila using the mip specific primers. Results: Overall, 100 bacterial isolates were isolated by culture from the 44 BAL samples including: Staphylococcus aureus (24, 31.2%), Streptococcus pyogenes (18, 23.4%), Enterococcus spp. (11, 14.3%), Acinetobacter baumannii (11, 14.3%), Pseudomonas aeruginosa (11, 14.3%), Enterococcus spp. (10, 13%), Micrococcus spp. (5, 6.5%), Staphylococcus epidermidis (5, 6.5%) and Klebsiella pneumoniae (5, 6.5%). PCR detected 4 positive samples (9.1%) for Chlamydia pneumoniae but no positive cases for Mycoplasma pneumoniae and Legionella pneumophila. Acinetobacter baumannii showed the highest resistance rate (81.8%) to aztreonam and ceftazidime. Seventy-five percent of the Staphylococcus aureus isolates were resistant to cefoxitin (MRSA) and 83.3% had the mecA gene. Vancomycin resistance was observed in 27.3% of the Enterococcus species (VRE). Resistance to piperacillin, cefotaxime, ciprofloxacin and imipenem was observed in 54.5%, 45.5%, and 36.4% of the Pseudomonas aeruginosa isolates, respectively. The frequency of organisms isolated from the ICU was higher (46%) than from other wards. Conclusions: The presence of MRSA, cephalosporins-resistant Enterobacteriaceae as well as Pseudomonas aeruginosa and Acinetobacter baumannii resistant against piperacillin, imipenem, cefotaxime, aztreonam and ciprofloxacin amongst different wards, especially the ICU ward of the surveyed hospitals, is a major healthcare concern and it is necessary to wisely scrutinize the preventive strategies for antibiotic resistant infections.

Pathogenic bacteria in cheese, raw and pasteurised milk.

BACKGROUND: Foodborne diseases, especially those transmitted by milk and its products, are worldwide problem. Milk is not only a complete food but also a unique medium for activating various bacteria such as Listeria monocytogenes, Staphylococcus aureus and Salmonella typhi. In recent years, numerous bacteria with multiple drug resistance patterns have appeared, and there have been many problems in infection control. Today, ranchers use antibiotics for control of the animal disease, and humans are constantly using animal products containing antibiotics. OBJECTIVE: The purpose of this study was to evaluate the contamination status of raw and pasteurised milk as well as local cheese and to find a rapid Multiplex PCR method for investigation of contamination. Determination of antibiotic resistant isolates is also desirable. MATERIALS AND METHODS: One hundred samples were collected from livestock and retail outlets using culture and molecular methods to identify S. aureus, L. monocytogenes and S. typhi. The antibiotic resistance pattern was determined for the isolates. RESULTS: In this study, culture results for 100 samples showed 10% S. aureus isolates while no cases of S. typhi and L. monocytogenes were detected. In real-time qPCR, S. aureus was isolated in 60% (n = 60) of samples, S. typhi in 53% (n = 53) and L. monocytogenes in 2% (n = 2). The results of sensitivity and specificity of Multiplex PCR for the three studied bacteria indicated general specificity of 72% and sensitivity of 80%. CONCLUSION: Based on the results of this study, it can be concluded that S. typhi, L. monocytogenes and S. aureus are more likely to be detected by real-time qPCR because of the high sensitivity of this test to culture. Multiplex method was not reliable in this study and cannot be suggested for rapid diagnosis.

Comparison of toxin-antitoxin expression among drug-susceptible and drug-resistant clinical isolates of Mycobacterium tuberculosis.

INTRODUCTION: Mycobacterium tuberculosis (MTB), the causative agent of tuberculosis (TB), is a significant global public health threat. Besides extensive multidrug resistance, MTB possesses several properties for long-term viability in the host as well as stress adaptation and resistance in harsh conditions. The role of toxin-antitoxin (TA) systems in disseminating and maintaining antimicrobial resistance in bacterial populations has also been demonstrated. This study aimed to evaluate differences in expression of MazEF (a well-known TA system) related genes (mazE3, mazF3, mazE6, and mazF6) amongst drug-susceptible and resistant MTB isolates in Iran. MATERIAL AND METHODS: A total of 20 confirmed clinical isolates of MTB including 10 drug-susceptible and 10 drug-resistant (nine MDR, and one XDR) species were included in this study. M. tuberculosis H37Rv was used as the standard strain. RNA extraction, cDNA synthesis, and relative quantitative real-time PCR were performed according to the standard procedures. RESULTS: Our analysis indicated significant enhanced expression of the mazE6 antitoxin gene in drug-susceptible isolates compared to drug-resistant isolates and the standard strain. The expression of the mazF6 toxin gene was also increased in drug-susceptible isolates compared with the standard strain. In drug-resistant isolates, the expression levels of mazF3 and mazF6 genes were significantly higher than that in the susceptible isolates and the standard strain. CONCLUSIONS: In this study, there was significant overexpression of mazE6 in drug-susceptible isolates. As well, mazF3 and F6 were overexpressed in drug-resistant isolates when compared with the standard strain. The changes in expression levels of MazEF6 associated genes were greater than that of MazEF3 in both groups of isolates.

Persister cells as a possible cause of antibiotic therapy failure in Helicobacter pylori.

BACKGROUND AND AIM: Due to the failure of antibiotic treatment and recurrence of infection in patients with Helicobacter pylori, this study was designed to find the possible cause of treatment failure and recurrence of the H. pylori infections in Ilam, Iran. METHODS: One hundred patients with specific symptoms of H. pylori infection were selected, and after taking a biopsy specimen, identification of H. pylori, antibiotic susceptibility assay, and persister cell assay were performed. In addition, after treatment, patients with persister cells were followed for possible recurrence of infection. Furthermore, an antibiotic susceptibility assay was performed. RESULTS: Our results demonstrated that, among 100 patients, 50% (n = 50) showed positive results for the existence of H. pylori. Among the susceptible isolates, 18% (n = 9) were persister cells that were sensitive to clarithromycin as confirmed by a 5 folds higher than the Minimal Inhibitory Concentration (MIC) of clarithromycin. The data were confirmed by following up the suspected patients. CONCLUSION: Our results demonstrated that persister cells in H. pylori infections may be responsible to recurrent infection and antibiotic treatment failure. However, more research is needed to obtain more information in this area.

Anticancer properties of colicin E7 against colon cancer.

INTRODUCTION: Cancer is a major public health problem in the modern world. Every year, new cases of cancer are diagnosed around the world. Cancer cells are altered cells that have escaped the mechanisms that regulate natural growth. Bacteriocins are cationic peptides synthesized by ribosomes that are secreted by almost all groups of bacteria. Some bacteriocins have shown selective toxicity to cancer cells compared to normal cells. This makes them other candidates for research and clinical trials. AIM: Due to the high prevalence of colon cancer and its therapeutic problems, this study was performed on colicin E7 to evaluate its anti-colon cancer properties. MATERIAL AND METHODS: For this reason, colE7 was cloned in pet32c vector and purified protein was affected on HT-29 cells to evaluate the expression of p53 and bcl2. RESULTS: Our in silco analysis demonstrated that colicin E7 has 87.23% confidence as anticancer peptide by ACPred-FL program. First, a PCR reaction was performed using specific primers of the colicin E7 gene, which formed the 1728 bp fragment that belongs to this gene. CONCLUSIONS: Colicin E7 decreased the expression of bcl2 and increased P53. The results of this study showed the general effect of colicin E7 on cancer cells in vitro, which can be evaluated in the future with further experiments.

Corrigendum to "Traditional and Modern Cell Culture in Virus Diagnosis"[Osong Public Health Res Perspect 2016;7(2):77-82].

[This corrects the article on p. 77 in vol. 7, PMID: 27169004.].