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Streptococcus mutans is a main organism of tooth infections including tooth decay and periodontitis. The aim of this study was to assess the influence of sucrose and starch on biofilm formation and proteome profile of S. mutans ATCC 35668 strain. The biofilm formation was assessed by microtiter plating method. Changes in bacterial proteins after exposure to sucrose and starch carbohydrates were analyzed using matrix-assisted laser desorption/ionization mass spectrometry. The biofilm formation of S. mutans was increased to 391.76% in 1% sucrose concentration, 165.76% in 1% starch, and 264.27% in the 0.5% sucrose plus 0.5% starch in comparison to biofilm formation in the media without sugars. The abundance of glutamines, adenylate kinase, and 50S ribosomal protein L29 was increased under exposure to sucrose. Upregulation of lactate utilization protein C, 5-hydroxybenzimidazole synthase BzaA, and 50S ribosomal protein L16 was formed under starch exposure. Ribosome-recycling factor, peptide chain release factor 1, and peptide methionine sulfoxide reductase MsrB were upregulated under exposure to sucrose in combination with starch. The results demonstrated that the carbohydrates increase microbial pathogenicity. In addition, sucrose and starch carbohydrates can induce biofilm formation of S. mutans via various mechanisms such as changes in the expression of special proteins.

Objective Klebsiella pneumoniae, one of the clinical superbugs, causes diverse infections because of its variable capsular antigens. This study focused on K. pneumoniae and aimed to assess any correlation between capsular serotype, capsule-associated virulence genes, and evaluate its resistance to conventional antibiotics in order to gain insight into any regional differences. Materials and methods A total of 61 K. pneumoniae collected from various clinical specimens were confirmed genotypically. Clinical and demographic data for all patients were reviewed. All isolates were subjected to antimicrobial susceptibility tests. Capsular serotyping and capsule-associated virulence genes were studied using the molecular method. Results All typeable isolates were typed into K5, K20, and K54 serotypes, and among them, K54 was observed to be predominant. The most common capsule-associated virulence genes comprised uge (93.4%), ycfM (91.8%), and wabG (88.5%), while wcaG (29.5%) and rmpA (21.3%) were noted at much lower prevalence rates. The gene wcaG was significantly associated with K54 positive isolates (p = 0.001), while rmpA was associated with K20 positive isolates (p = 0.01). Conclusion Serotype K54 had a high frequency in isolates collected from patients with pulmonary diseases, while serotype K20 was associated with burn patients. Carbapenems and levofloxacin were the best therapeutic options for the treatment of infections with serotypes K20 and K54.

Helicobacter pylori (H. pylori) infection is the most common cause of gastric cancer (GC). This microorganism is genetically diverse; GC is caused by several genetic deregulations in addition to environmental factors and bacterial virulence factors. lncRNAs (long noncoding RNAs) are significant biological macromolecules in GC, have specific functions in diseases, and could be therapeutic targets. Altered lncRNAs can lead to the abnormal expression of adjacent protein-coding genes, which may be important in cancer development. Their mechanisms have not been well understood, so we are going to investigate the risk of GC in a population with both high lncRNA and H. pylori infection.

Background Enterococcus faecalis is a significant cause of nosocomial infections and other diseases, including endocarditis, bacteremia, and urinary tract infections. This microorganism forms biofilms to overcome difficult environmental conditions, such as lack of oxygen, lack of water, and the presence of antimicrobials. These biofilms make diseases difficult by changing their proteome contents, protecting the bacterium, and increasing their pathogenicity. This study aimed to evaluate gentamicin's effect on proteome changes and biofilm formation in E. faecalis. Method Twenty-five clinical isolates and one standard isolate were selected for the experiments. A label-free/gel-free proteomic and microtiter plate techniques were used to study proteome changes and biofilm formation, respectively. Results Gentamicin significantly increased the biofilm formation in 62% of isolates and the rest of the isolates; no significant change was observed. The abundance of lactate utilization protein C, ribosomal RNA small subunit methyltransferase H, and protein translocase subunit SecA were increased. However, the abundances of proteins effective in cell division and metabolism, such as replication initiation protein and segregation and condensation protein A, were decreased. Conclusion The present study's findings exhibited that antibiotics might have adverse effects on treatment and increase microorganisms' pathogenicity. It was observed in gentamicin as induction of biofilm formation through different mechanisms, particularly changes in the expression of specific proteins in E. faecalis.

Clustered regularly interspaced short palindromic repeat (CRISPR)-Cas systems are one of the factors which can contribute to limiting the development and evolution of antibiotic resistance in bacteria. There are three genomic loci of CRISPR-Cas in Enterococcus faecalis. In this study, we aimed to assess correlation of the CRISPR-Cas system distribution with the acquisition of antibiotic resistance among E. faecalis isolates. A total of 151 isolates of E. faecalis were collected from urinary tract infections (UTI) and dental-root canal (DRC). All isolates were screened for phenotypic antibiotic resistance. In addition, antibiotic resistance genes and CRISPR loci were screened by using polymerase chain reaction. Genomic background of the isolates was identified by random amplified polymorphic DNA (RAPD)-PCR. The number of multidrug-resistant E. faecalis strains were higher in UTI isolates than in DRC isolates. RAPD-PCR confirmed that genomic background was diverse in UTI and DRC isolates used in this study. CRISPR loci were highly accumulated in gentamycin-, teicoplanin-, erythromycin-, and tetracycline-susceptible strains. In concordance with drug susceptibility, smaller number of CRISPR loci were identified in vanA, tetM, ermB, aac6’-aph(2”), aadE, and ant(6) positive strains. These data indicate a negative correlation between CRISPR-cas loci and antibiotic resistance, as well as, carriage of antibiotic resistant genes in both of UTI and DRC isolates.

Helicobacter pylori (H. pylori) infection is the most common cause of gastric cancer (GC). This microorganism is genetically diverse; GC is caused by several genetic deregulations in addition to environmental factors and bacterial virulence factors. lncRNAs (long noncoding RNAs) are significant biological macromolecules in GC, have specific functions in diseases, and could be therapeutic targets. Altered lncRNAs can lead to the abnormal expression of adjacent protein-coding genes, which may be important in cancer development. Their mechanisms have not been well understood, so we are going to investigate the risk of GC in a population with both high lncRNA and H. pylori infection.

Background and Objectives: Trend analysis reveals that Klebsiella pneumoniae has witnessed a steep enhancement in the antibiotic resistance and virulence over the last few decades. The present investigation aimed at a comprehensive approach investigating antibiotic susceptibility including, extended spectrum beta-lactamase (ESBL) and AmpC β-lactamase (AmpC) resistance and the prevalence of virulence genes among the K. pneumoniae isolates. Materials and Methods: Sixty-one K. pneumoniae isolates were obtained from various clinical infections. Antimicrobial susceptibility was performed by disk diffusion method. The Mast® D68C test detected the presence of ESBLs and AmpCs phenotypically, and later presence of ESBL and AmpC genes was observed by polymerase chain reaction (PCR). Multiplex-PCR was performed to investigate various virulence genes. Results: Amongst 61 K. pneumoniae isolates, 59% were observed as ESBL and 14.7% as AmpC producers. All ESBL producers were positive for bla CTX-M-15 , while bla CTX-M-14 was observed in 54.1% isolates. The frequency of AmpC genes was as follows: bla CMY-2 (60.7%) and bla DHA-1 (34.4%). The most frequent virulence genes were those encoding enterobactin and lipopolysaccharide. Presence of mrkD was associated with bla DHA-1 gene, while bla CMY-2 significantly (p≤0.05) correlated with the presence of iutA and rmpA virulence genes. bla DHA-1 positive isolates had urine as a significant source, while bla CMY-2 positive isolates were mainly collected from wound exudates (p≤0.05). Conclusion: Our results highlight that ESBL and AmpC production along with a plethora of virulence trait on K. pneumoniae should be adequately considered to assess its pathogenesis and antibiotic resistance.

Background and Objectives: Trend analysis reveals that Klebsiella pneumoniae has witnessed a steep enhancement in the antibiotic resistance and virulence over the last few decades. The present investigation aimed at a comprehensive approach investigating antibiotic susceptibility including, extended spectrum beta-lactamase (ESBL) and AmpC β-lactamase (AmpC) resistance and the prevalence of virulence genes among the K. pneumoniae isolates. Materials and Methods: Sixty-one K. pneumoniae isolates were obtained from various clinical infections. Antimicrobial susceptibility was performed by disk diffusion method. The Mast® D68C test detected the presence of ESBLs and AmpCs phenotypically, and later presence of ESBL and AmpC genes was observed by polymerase chain reaction (PCR). Multi- plex-PCR was performed to investigate various virulence genes. CMY-2 Results: Amongst 61 K. pneumoniae isolates, 59% were observed as ESBL and 14.7% as AmpC producers. All ESBL CTX-M-15 producers were positive for bla CTX-M-15 , while bla CTX-M-14 was observed in 54.1% isolates. The frequency of AmpC genes was CMY-2 as follows: bla CMY-2 (60.7%) and bla DHA-1 (34.4%). The most frequent virulence genes were those encoding enterobactin and DHA-1 lipopolysaccharide. Presence of mrkD was associated with bla CMY-2 DHA-1 gene, while bla significantly (p≤0.05) correlated DHA-1 with the presence of iutA and rmpA virulence genes. bla positive isolates had urine as a significant source, while bla positive isolates were mainly collected from wound exudates (p≤0.05). Conclusion: Our results highlight that ESBL and AmpC production along with a plethora of virulence trait on K. pneumoni- ae should be adequately considered to assess its pathogenesis and antibiotic resistance.

Using laser treatments and calcium and phosphate compounds to enhance remineralization has been investigated in this study. Seventy two premolar teeth were divided into four groups of 18: 1) control group; 2) laser therapy group; 3) CPP-ACP paste group; and 4) laser therapy and CPP-ACP group. Mineralization and remineralization of samples were investigated by Diagnodent. Data were reported using descriptive statistics (mean, standard deviation) and One Way ANOVA; they were analyzed using SPSS.16 statistical software. Statistical analysis showed that groups 3 and 4 had the highest rate of remineralization compared to groups 1 and 2. According to the results of this study, mineralization ranged decreasingly from group 4 to groups 3, 2, and 1, respectively. The antibacterial effect of laser therapy, leading to remineralization of calcium and phosphorus compounds, was the most effective on controlling root decay.

Background Methicillin-resistant staphylococcus aureus (MRSA) causes surgical site infections (SSIs) and complicates the treatment of these infections. Vancomycin is the drug of choice for infections due to MRSA but creep MIC of vancomycin may be associated with failure in antibiotic therapy. The aim of the present study was to determinate the prevalence, antibiotic susceptibility patterns of MRSA in patients suffering from SSIs and determination of vancomycin MIC in these isolates. Methods Detection of S. aureus in 100 aspirated specimens from SSIs was performed by the standard microbiology tests. MRSA was detected by phenotypic and molecular methods. The disk diffusion, E-test and agar dilution methods were performed for determination of antibiotic susceptibility patterns, the vancomycin MIC and oxacillin MIC. The results were interpreted according to guidelines of the Clinical and Laboratory Standards Institute (CLSI). Results Of 24 S. aureus isolates, 20 (83.33%) were recognized as the MRSA by 30 μg cefoxitin disk from 100 specimens and all were confirmed by PCR. High frequency of resistance was observed to clindamycin, erythromycin, gentamicin, ciprofloxacin and chloramphenicol while all isolates were susceptible to vancomycin, linezolid, and mupirocin. The range of vancomycin and oxacillin MICs were 0.25 to 2 and 0.5 to 128 μg/ml, respectively. Vancomycin-creep MIC was detected in two isolates from the superficial wound and surgical respiratory tract infections, and one of the patients died. Conclusion The findings of this study show a high frequency of MRSA in SSIs. Due to the elevated MIC of vancomycin, we suggest consumption of other effective drugs for the treatment of SSIs.

Introduction Adhesion of bacteria, especially Streptococcus mutans (S. mutans), to the surface of tooth restorations is a factor in the etiology of secondary caries. Given the ever-increasing popularity of bleaching procedures, the aim of the present study was to evaluate adhesion of S. mutans and surface roughness (SR) of microhybrid composite resin and giomer subsequent to the application of 15% carbamide peroxide. Materials and methods Twenty disk-shaped samples were prepared from each material, measuring 8 mm in diameter and 2 mm in thickness. Then, the samples of each material were divided into two groups (n = 10): (a) microhybrid without bleaching; (b) microhybrid with bleaching; and (c) giomer without bleaching; and (d) giomer with bleaching. The samples in groups I and III were immersed in artificial saliva for 14 days without any bleaching procedure; the samples in groups II and IV underwent a bleaching procedure on their polished surfaces with 15% carbamide peroxide for 14 days (4 hours of bleaching and 20 hours of immersion in artificial saliva). The SR of all the samples was determined with the use of a profilometer. The samples were added to the culture medium after 4 hours of placement in a microbial suspension at 37°C; after 24 hours of incubation at 37°C, the bacterial counts, indicating the number of bacteria adhering to the surface, were determined by counting them in the plates containing the solid culture medium. Results The type of the restorative material had a significant effect on SR, with greater SR in giomer (p = 0.03). However, bleaching had no significant effect on SR (p = 0.099). In relation to the rate of bacterial adhesion (BA), both the types of the restorative materials and bleaching procedures were significantly effective; in this context, there was more BA in microhybrid composite resin samples that did not undergo bleaching (p < 0.001). Bleaching resulted in the adhesion of S. mutans to the surface of both materials decrease. Pearson's correlation coefficient did not reveal any correlation between BA and SR (p = 0.42). Conclusion The BA was higher in microhybrid composite resin, and SR was higher in giomer. The BA was higher in samples that did not undergo a bleaching procedure. Clinical significance There is no change in the SR of microhybrid composite resin and giomer after application of 15% carbamide peroxide; therefore, it is not necessary to polish or replace these restorative materials after bleaching. In addition, use of 15% carbamide peroxide does not increase caries risk. How to cite this article Mohammadi N, Mowlaie S, Savadi- Oskoee S, Ebrahimi ME, Rikhtegaran S, Rahbar M, Pirzadeh T. Effect of 15% Carbamide Peroxide on the Surface Roughness and Adhesion of Streptococcus mutans to Microhybrid Composite Resin and Giomer. World J Dent 2017;8(4):288-295.

Background: Clostridium difficile is known as a prevalent pathogen leading to infections ranging from mild diarrhea to severe disease and death. The aim of the present study was to evaluate the incidence of C. difficile from inpatients with nosocomial diarrhea hospitalized in different wards in the northwest region of Iran. Methods: In this cross-sectional study, 485 diarrheal stool samples were collected from 384 patients referred from different wards of Imam Reza, Sina and Pediatric hospitals, Tabriz and transferred to the laboratory from 25 March 2015 till 1 March 2018. Immuno-chromatographicassay for detection of toxins A and B of C. difficile was used for identification. Results: Clostridium difficile was isolated from 24 (4.7%) out of 485 samples. Fifteen patients(62.5%) were males and 9 were females (37.5%). Twelve positive patients were from the gastrointestinal ward (50%), 5 patients (20.8%) from surgery ward, 3 patients from infectious disease ward (12.5%), 3 patients from rheumatology ward (12.5%) and 1 patient (4.1%) were collected from neurology ward. 95.3% of diarrhea samples had no signs from toxin A and B. Conclusion: These results indicate most of infected patients were from the gastrointestinaland surgery wards which show a different pattern of infection compared to previous studies.The neurology department had the lowest rate of infection. C. difficile is a health threat afterantibiotic consumption and for health promotion, developing strategies for less antibioticconsumption and preventing these emerging infections is critical. The low rate of this infection shows improvement in knowledge and effect of stewardships in physicians.

Introduction Enterococcus faecalis is one of the important causative agents of nosocomial and life-threatening infections in human. Several studies have demonstrated that the presence of CRISPR- cas is associated with antibiotic susceptibility and lack of virulence traits. In this study, we aimed to assess the phenotypic and genotypic virulence determinants in relation to CRISPR elements from the dental-root canals and hospital-acquired isolates of E. faecalis .Methods and materials Eighty-eight hospital-acquired and 73 dental-root canal isolates of E. faecalis were assessed in this study. Phenotypic screening of the isolates included biofilm formation, and gelatinase and hemolysis activities. Genotypical screening using PCR was further used to evaluate the presence of CRISPR elements and different virulence-associated genes such as efaA , esp , cylA , hyl , gelE , ace , ebpR , and asa1 .Results Biofilm formation, and gelatinase and hemolysis activity were detected in 93.8%, 29.2% and 19.2% of the isolates, respectively. The most prevalent virulence-associated gene was ace , which was followed by efaA , whereas cylA was the least identified. The presence of CRISPR1- cas , orphan CRISPR2 and CRISPR3- cas was determined in 13%, 55.3% and 17.4% of the isolates, respectively. CRISPR elements were significantly more prevalent in the dental-root canals isolates. An inverse significant correlation was found between CRISPR- cas loci, esp and gelE , while direct correlations were observed in the case of cylA , hyl , gelE (among CRISPR-loci 1 and 3), asa1 , ace , biofilm formation, and hemolysis activity.Conclusion Findings, therefore, indicate that CRISPR- cas might prevent the acquisition of some respective pathogenicity factors in some isolates, though not all; so selective forces could not influence pathogenic traits.

Introduction: Enterococcus faecalis is one of the important causative agents of nosocomial and life-threatening infections in human. Several studies demonstrated that the presence of CRISPR-cas is associated with the antibiotic susceptibility and lack of virulence traits. In this study, we aimed to assess the relation between the phenotypic and genotypic virulence determinants of E. faecalis with the CRISPR elements in the dental-root canal and hospital-acquired isolates.Methods and materials: Eighty-eight hospital-acquired and 73 dental-root canal isolates of E. faecalis were subjected for study. The phenotype tests including biofilm formation, gelatinase and hemolysis activity were performed and the genotype characteristics including efaA, esp, cylA, hyl, gelE, ace, ebpR, and asa1 were performed by PCR methods. Presences of different types of CRISPR-cas system were determined by PCR.Results: Biofilm formation, gelatinase and hemolysis activity were detected in 93.8%, 29.2% and 19.2% of the isolates, respectively. The most gene encoding virulence traits were ace, followed by efaA and the lowest was cylA. The presence of CRISPR1-cas, orphan CRISPR2 and CRISPR3-cas were determined in 13%, 55.3%, and 17.4% of isolates, respectively, which were present in proportionally more in the dental-root canal. Inverse correlation were found significantly between CRISPR-cas loci, esp and gelE, and direct correlations were found in cylA, hyl, gelE (between some CRISPR-loci), asa1, ace, biofilm formation, gelatinase and hemolysis activitiesConclusion: Findings indicates that CRISPR-cas might prevent the acquisition of some respective pathogenicity factors in some isolates not all, and could not be selective forces to influence pathogenic traits.

Staphylococcus aureus is one of the most common bacterial pathogens isolated from diabetic foot infections (DFIs). The increasing prevalence of meticillin-resistant S. aureus (MRSA) in patients with diabetes is associated with complications. The aim of this study was to determine the prevalence of S. aureus in DFIs and antibiotic susceptibility patterns of MRSA and non-MRSA isolates. Identification of S. aureus and MRSA was performed by the phenotypic and molecular methods. The Kirby-Bauer and agar dilution methods were performed for determination of antibiotic susceptibility patterns. Thirty-four isolates of S. aureus were isolated from March 2014 to February 2015. The rate of MRSA was 38.23 % according to the disk cefoxitin and oxacillin agar dilution methods, and as by PCR method 12) 35.29 %), isolates were found to have the mecA gene. All MRSA and non-MRSA isolates were susceptible to linezolid and vancomycin. The resistance rate to ceftriaxone was high followed by amoxicillin-clavulanic acid, tetracycline, gentamicin, and erythromycin. The most common bacterial pathogen isolated from DFIs was S. aureus. To ensure effective treatment, accurate detection of MRSA is critical. Our findings showed that MRSA isolates had high-level resistance to antimicrobial agents and that appropriate antibiotic therapy, based on the antibiotic susceptibility pattern, is essential to ensure a good result.

Objectives: Dental practice contains the use of instruments and multiuse items that should be sterilized or disinfected properly. The aim of the current study was to investigate the effect of microwave irradiation on dental stone cast disinfection in moist and dry condition. Materials and Methods: In this in vitro study, 76 stone casts were prepared by a sterile method. The casts were contaminated by Pseudomonas aeruginosa (ATCC 9027), Staphylococcus aureus (ATCC 6538), Enterococcus faecalis (ATCC 29212) as well as Candida albicans (ATCC 10231). Half the samples were dried for two hours and the other half was studied while still moist. The samples were irradiated by a household microwave at 600 W for 3, 5 and 7 minutes. The microorganisms on the samples were extracted by immersion in tryptic soy broth and .001 ml of that was cultured in nutrient agar media, incubated overnight and counted and recorded as colony forming unit per milliliter (CFU/mL). Results: The findings showed that microorganisms reduced to 4.87 logarithm of CFU/mL value on dental cast within seven minutes in comparison with positive control. Although microbial count reduction was observed as a result of exposure time increase, comparison between moist and dried samples showed no significant difference. Conclusions: Seven-minute microwave irradiation at 600 W can effectively reduce the microbial load of dental stone casts. Wetting the casts does not seem to alter the efficacy of irradiation. Keywords: Microwave Disinfection; Dental Stone Casts; Irradiation Times

Objective: The disinfection of dental stone casts using microwave radiation has been shown, but doubts remain regarding its efficacy under various conditions. The aim of the present study was to evaluate the efficacy of microwave disinfection on wet and dry dental stone casts contaminated by a resistant microorganism. Material and methods: In this in vitro study, 34 stone half-casts were prepared, contaminated with Bacillus subtilis and divided into two groups. After drying the specimens of one group for 15 minutes using 450 W microwave energy, all the wet and dry specimens were exposed to 900 W microwave energy for 5 minutes. Specimens were then individually transferred to nutrient broth culture medium and after 10 minutes, one milliliter from each tube was cultured in nutrient agar media for 24 hours, and the colonies were counted in CFU/mL. Data were analyzed using multifactorial ANOVA and Bonferroni tests. Results: Casts in both wet and dry groups were disinfected to a high level (6 log), with no statistically significant differences between them (P, Zielsetzung: Obwohl die Desinfektion von Dentalabgüssen mit Mikrowellen bereits gezeigt werden konnte, bestehen Zweifel hinsichtlich der Wirksamkeit unter verschiedenen Bedingungen. Daher sollte die Wirksamkeit vergleichend auf nassen und trockenen Dentalabgüssen nach Kontamination mit Bacillus subtilis in vitro geprüft werden. Material und Methode: 34 Zahnabgüsse wurden präpariert, mit B. subtilis kontaminiert und in zwei Gruppen aufgeteilt. In der ersten Gruppe wurden die Prüfkörper mit 450 W Mikrowellenenergie für 15 min getrocknet. Danach wurden die getrockneten und parallel die feucht belassenen Prüfkörper für 5 min mit 900 W Mikrowellenenergie exponiert, für 10 min in Nährbouillon überführt, davon 1 ml auf Agar ausplattiert und nach 24 h die Kolonien gezählt. Die Daten wurden nach mehrfaktorieller Varianzanalyse mittels ANOVA mit dem Bonferroni-Test analysiert. Ergebnisse: In beiden Gruppen wurde eine Abtötung um 6-log ohne signifikanten Unterschied erreicht (P, GMS Hygiene and Infection Control; 12:Doc09

Purpose of the research In order to gain a better understanding of the role of several mechanisms in antibiotic resistance in Pseudomonas aeruginosa clinical isolates obtained from CF and burn patients, we evaluated gene expression of efflux pumps MexAB-OprM and MexXY(-OprA), the natural β-lactamase AmpC and outer membrane porin protein OprD. Also, the presence of genes encoding Ambler classes A, B β-lactamases and aminoglycoside modifying enzymes (AMEs) was examined. Principal results Piperacillin–tazobactam and amikacin retained the highest in vitro activities among 21 CF and 27 burn P. aeruginosa isolates. Based on Enterobacterial Repetitive Intergenic Consensus (ERIC) PCR, 15 distinct patterns were detected. There were 5 CF and 6 burn isolates harbored PER-1 and VEB-1, respectively. Among AMEs, involved in resistance of anti-Pseudomonas aminoglycosides, aac(6 ′ )-Ib was the most prevalent gene. Among CF isolates, mexA overexpression was the most prevalent mechanism (47.6%) followed by mexX (42.8%), ampC (9.5%) and oprD downregulation (4.7%). Among burn isolates, the prevalence of mexX , mexA , and ampC overexpression was 62.9%, 74%, and 11.1%, respectively. Downregulation of oprD was observed in 14.8% of burn isolates. Major conclusions Among CF isolates, mexX and mexA overexpression were the major contributing factors to aminoglycoside (gentamicin) and carbapenem (meropenem) resistance, respectively while among burn isolates, AMEs in conjunction with mexX hyperexpression were identified to be responsible for aminoglycoside resistance. Also mexA overexpression was partially associated with carbapenem resistance. Moreover, cephalosporin resistance was linked to overexpression of mexA and/or mexX. The impact of interplay between different resistance mechanisms on resistant phenotypes was more complicated among burn than CF isolates.

Escherichia coli is a gram-negative bacterium and it causes a variety of diseases in humans. It causes a wide range of clinical infections in humans; urinary tract infections is the most prevalent infection caused by uropathogenic Escherichia coli. In recent years, the observation of antibiotic-resistant genes such as resistance to colistin, makes the Escherichia coli resistant to antibiotics like colistin (polymyxin E), because of that the use of new therapies like peptide nucleic acid (PNA) has attracted the consideration of scientists. The aim of this study is the assessment of the inhibitory role of PNA against mcr-1 gene and reduction of mcr-1 gene expression and MIC in colistin resistant E. coli by PNA. NCBI database was used to design PNA. Our study was carried out on E. coli KP81 bacteria containing the mcr-1 gene. Microbroth dilution (MIC) method was used to survey phenotypic sensitivity and determine the sensitivity of the bacteria to the colistin antibiotic. E. coli KP81 isolates were further investigated by polymerase chain reaction to assess the presence of mcr-1 genes and target genes were quantified by real-time PCR assay using specific primers. The MIC result after treatment with specific PNA showed that the resistance to colistin reduced about three fold and the resistance level dropped from 32 μg/ml to 4 μg/ml. The expression analysis of mcr-1 gene in E. coli KP81 isolate indicates the PNA, 95% reduced the expression of the mcr-1 gene. Our observations showed that by inhibiting the expression of mcr-1, sensitivity to colistin can be defeated. Using higher concentrations of PNA and an in vivo study can reveal more clinical application of this method.

Background: Diarrhea is the most frequent health problem among children in developing countries. Defining the etiology of acute diarrhea is critical to disease therapy and prevention. Some anaerobic bacteria such as Enterotoxigenic Bacteroides fragilis (ETBF) strains cause diarrheal disease by production of enterotoxin in children less than 5 years old. Objectives: This study aimed to evaluate the prevalence of ETBF among common bacteria and viruses causing diarrhea in children aged less than five years. Materials and Methods: One hundred diarrheal stools were cultured for detection of aerobic and anaerobic pathogen bacteria by direct plating on selective media and antibiotic susceptibility tests were performed according to clinical and laboratory standards institute (CLSI) guidelines on isolates of ETBF. The enterotoxigenic gene among B. fragilis isolates was also investigated using the polymerase chain reaction (PCR) method. Detection of viral pathogens was carried out using the latex agglutination test. Results: Ten B. fragilis were isolated from 100 diarrheal fecal specimens. All isolates were susceptible to metronidazole, while 10% were susceptible to clindamycin. Four (40%) ETBF were isolated. Rotaviruses (57.2%) and adenoviruses (18.6%) were the most frequently detected etiological agents. Conclusions: ETBF is one of the etiological agents that may cause diarrhea in children but it is not the commonest of them. Metronidazole is still an effective antibiotic against B. fragilis. Viruses are the most important etiological agents of diarrhea in children less than 5 years of age.

Background: Clostridium perfringens, a Gram-positive, anaerobic bacterium that produces at least 16 virulence factors including 12 toxins (α-ν), enterotoxin, hemolysin and neuraminidase, can create variable pathogenic condition, ranging from a food poisoning to life-threatening myonecrosis. Among C. perfringens strains, resistance to the drug choices such as penicillin as well as to alternatives of penicillin like metronidazole and clindamycin has also been observed. Objectives: The aim of this study was to determine the resistance of isolated toxigenic and non-toxigenic C. perfringens strains against common antimicrobial agents. Materials and Methods: In this descriptive study, a total of 136 stool specimens were collected. At first, cooked meat medium enrichment method was performed on samples at 45°C. Thereafter, a loopful of the enriched culture was transferred to blood agar and incubated anaerobically at 37°C for 24-72 hours. Colonies with double zone of hemolysis were identified by different biochemical tests such as phospholipase C (lecithinase) test, indole and urease production. The Minimum Inhibitory Concentration (MIC) for common antibiotics was determined by Etests (Epsilometer) and duplex Polymerase Chain Reaction (PCR) reaction was performed with specific primers for amplification of cpe (426 bp) and plc (283 bp) Genes. Results: Of 136 stool samples including diarrhea [48] and non-diarrhea [88] ones, 83 (61.02%) C. perfringens were cultured. Of these 83, 79 C. perfringens isolates showed the alpha-toxin (phospholipase C) production gene by PCR. Respectively, 3 (9.09%) and 2 (4.34%) cpe genes were present in diarrhea and non-diarrhea samples. Of 79 isolates of C. perfringens, 34 (43.03%) cases showed no resistance, 18 (22.78%) had one resistance and 27 (34.17%) isolates had multiple resistance to imipenem, metronidazole, ceftriaxone, clindamycin, chloramphenicol, and penicillin. Conclusions: Periodic evaluation of antimicrobial susceptibility for C. perfringens should be performed. Harboring of enterotoxigenic C. perfringens in individuals not necessarily results in diarrhea.

Background: Surgical Site Infections (SSIs) are infections of incision or deep tissue at operation sites. These infections prolong hospitalization, delay wound healing, and increase the overall cost and morbidity. Objectives: This study aimed to investigate anaerobic and aerobic bacteria prevalence in surgical site infections and determinate antibiotic susceptibility pattern in these isolates. Materials and Methods: One hundred SSIs specimens were obtained by needle aspiration from purulent material in depth of infected site. These specimens were cultured and incubated in both aerobic and anaerobic condition. For detection of antibiotic susceptibility pattern in aerobic and anaerobic bacteria, we used disk diffusion, agar dilution, and E-test methods. Results: A total of 194 bacterial strains were isolated from 100 samples of surgical sites. Predominant aerobic and facultative anaerobic bacteria isolated from these specimens were the members of Enterobacteriaceae family (66, 34.03%) followed by Pseudomonas aeruginosa (26, 13.4%), Staphylococcus aureus (24, 12.37%), Acinetobacter spp. (18, 9.28%), Enterococcus spp. (16, 8.24%), coagulase negative Staphylococcus spp. (14, 7.22%) and nonhemolytic streptococci (2, 1.03%). Bacteroides fragilis (26, 13.4%), and Clostridium perfringens (2, 1.03%) were isolated as anaerobic bacteria. The most resistant bacteria among anaerobic isolates were B. fragilis. All Gram-positive isolates were susceptible to vancomycin and linezolid while most of Enterobacteriaceae showed sensitivity to imipenem. Conclusions: Most SSIs specimens were polymicrobial and predominant anaerobic isolate was B. fragilis. Isolated aerobic and anaerobic strains showed high level of resistance to antibiotics.

Acinetobacter baumannii has emerged as one of the most challenging healthcare-related pathogens and its occurrence has increased worldwide, especially in patients admitted to intensive care units. A. baumannii isolates are frequently resistant to multiple antimicrobial agents and there are recent reports of isolates resistant to virtually all clinically relevant drugs. In the present study, the in vitro activities of tigecycline, minocycline and doxycycline against 67 MDR-AB isolates recovered from 29 burn and 38 non-burn Iranian patients hospitalised in Tehran and Tabriz, respectively, were studied. Tigecycline and minocycline may be still considered effective therapeutic options for MDR-AB infections. However, ongoing monitoring of A. baumannii susceptibility to these antibiotics is required.

antibiotics. Patients and Methods: A total of 188 fecal samples including 59 samples from hospitalized patients, 84 samples from outpatients, and 45 samples from healthy individuals were collected. The samples were cultured in Bacteroides- Bile- Esculine agar and KanamycinVancomycin-Laked Blood media and were incubated in anaerobic atmosphere at 37°C for at least 48 hours. Suspected one millimeter sized colonies with black surroundings, were selected and further studied using MID8, as well as biochemical tests. For MIC determination of antibiotics against isolated B. fragilis, Etest was used. Results: There wasn’t any difference between antibiotic resistance patterns of isolated B. fragilis from hospitalized patients or outpatients, including diarrheal and non-diarrheal cases, and resistant pattern of isolates from healthy individuals. All or most of isolated B. fragilis were susceptible to imipenem (100%), metronidazole (95%), rifampin (100%) and piperacillin/tazobactam (95%). On the contrary, they exhibited resistance to other antibiotics such as clindamycin (90%), and chloramphenicol (55%). Conclusions: In the present study, we have figured out that a number of the important anaerobic infections treatment antibiotics have lost partly or totally their effectiveness on B. fragilis.

Background: Enterotoxigenic Bacteroides fragilis (ETBF) are one of the most important anaerobic bacteria whichcause diarrhea in human beings. A bft gene is coded for enterotoxin production called fragilysin. Most of them have acquired resistance to antianaerobicbacteria agent like other facultative anaerobic bacteria. E test and different dilution methods are usually performed for antimicrobial susceptibility determination of B. fragilis. Objectives: The aims of this study are to recognize ETBF by PCR method and also to evaluate efficiency thedisk diffusion method (DDM) in comparison with the E tests for antimicrobial susceptibility of B. fragilis isolates. Materials and Methods: bft gene was detected among 157 B. fragilis isolated from patients and healthy individuals by PCR. Antimicrobial susceptibility of all isolates was determined by DDM and E tests methods. Results: Nineteen (12.1%) B. fragilis containing bft gene from diarrheic (n = 14) and nondiarrheic (n = 5) feces were detected among 157 B. fragilis isolates. The highest resistance for ciprofloxacin, cefotaxim, cefoxitin with DDM and E test were 100%, 60%, and 65% respectively, while the lowest resistance in two methods was obtained for imipenem, piperacillin / tazobactam, and metronidazol. 100% agreement for some of antibiotics such as imipenem (P ? 0.05), and no correlation for others were observed among the antimicrobial susceptibility results obtained by the two methods (P ? 0.05). Conclusions: The presence of bft gene in B. fragilis isolates wouldnot certainly result in diarrheaamong patients. There is not enough accordance between DDM and Swedish E tests for antimicrobial susceptibility of B. fragilis for some antibiotics, although in other cases a good agreement was observed.

Purpose: The antimicrobial activity of doripenem in comparison of imipenem, meropenem and ertapenem among Pseudomonas aeruginosa isolated from burn and Cystic Fibrosis (CF) patients were determined. Methods: Metallo-β-lactamase (MBL) genes in imipenem non susceptible P. aeruginosa isolates were detected using PCR method. The in vitro susceptibilities of doripenem, imipenem, meropenem and ertapenem were determined by Etests. MIC50 and MIC90 for corresponding antibiotics were determined individually in burn and CF isolates. Results: Among isolates which were resistant to imipenem, 16 isolates were positive for the bla IMP gene. All isolates had no bla VIM gene. All MBL producing isolates were excluded. MIC50/MIC90 of doripenem in CF and burn isolates were 0.75/>32 and >32/>32 mg/L respectively. The corresponding values for imipenem in CF and burn isolates were 2/>32 and >32/>32 mg/L, respectively. Conclusion: The susceptibility rate of doripenem is higher than that of imipenem and meropenem among P.aeruginosa isolated from CF patients, whereas, there is no difference between the efficiency of doripenem and old carbapenems in non MBL producing P.aeruginosa isolates in burn patients., Advanced Pharmaceutical Bulletin; eISSN 2251-7308

The growing incidence of community acquired infection due to Extended -Spectrum Beta- Lactamase (ESBL) - and plasmid-mediated AmpC β-lactamase prducing bacteria represent a great concern because there are few therapeutic choices. This study was aimed to determine the prevalence of faecal carriage of ESBL producing Klebsiella spp. and Shigella spp. among inpatient and outpatient and their phenotype-genotype resistance correlation that conveyed ESBL with or without AmpC genes at a university hospital in Tabriz, Iran. During March to May 2015, 200 faecal samples from hospitalized and non -hospitalized patients without gas trointestinal illness and diarrhea were cultured on MacConkey agar plate supplemented with 2 μg/mL of cefotaxime.