Prevalence of the CRISPR-cas system and its association with antibiotic resistance in clinical Klebsiella pneumoniae isolates.

BACKGROUND AND OBJECTIVE(S): CRISPR-Cas is a prokaryotic adaptive immune system that protects bacteria and archaea against mobile genetic elements (MGEs) such as bacteriophages plasmids, and transposons. In this study, we aimed to assess the prevalence of the CRISPR-Cas systems and their association with antibiotic resistance in one of the most challenging bacterial pathogens, Klebsiella pneumoniae. MATERIALS AND METHODS: A total of 105 K. pneumoniae isolates were collected from various clinical infections. Extended-spectrum ß-lactamases (ESBLs) phenotypically were detected and the presence of ESBL, aminoglycoside-modifying enzymes (AME), and CRISPR-Cas system subtype genes were identified using PCR. Moreover, the diversity of the isolates was determined by enterobacterial repetitive intergenic consensus (ERIC)-PCR. RESULTS: Phenotypically, 41.9% (44/105) of the isolates were found to be ESBL producers. A significant inverse correlation existed between the subtype I-E CRISPR-Cas system's presence and ESBL production in K. pneumoniae isolates. Additionally, the frequency of the ESBL genes blaCTX-M1 (3%), blaCTX-M9 (12.1%), blaSHV (51.5%), and blaTEM (33.3%), as well as some AME genes such as aac(3)-Iva (21.2%) and ant(2'')-Ia (3%) was significantly lower in the isolates with the subtype I-E CRISPR-Cas system in comparison to CRISPR-negative isolates. There was a significant inverse correlation between the presence of ESBL and some AME genes with subtype I-E CRISPR-Cas system. CONCLUSION: The presence of the subtype I-E CRISPR-Cas system was correlated with the antibiotic-resistant gene (ARGs). The isolates with subtype I-E CRISPR-Cas system had a lower frequency of ESBL genes and some AME genes than CRISPR-negative isolates.

Comparing proteome changes involved in biofilm formation by Streptococcus mutans after exposure to sucrose and starch.

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.

Dysregulation of lncRNA in Helicobacter pylori-Infected Gastric Cancer Cells.

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.

Role of CRISPR-Cas system on antibiotic resistance patterns of Enterococcus 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.

Induction of proteome changes involved in biofilm formation of Enterococcus faecalis in response to gentamicin.

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.

CRISPR-cas system in the acquisition of virulence genes in dental-root canal and hospital-acquired isolates of Enterococcus faecalis.

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. 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. Biofilm formation, gelatinase, and hemolysis activities 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 canal 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. 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. Abbreviations: BHI: brain-heart infusion agar; CRISPRs: Clustered regularly interspaced short palindromic repeats; Esp: Cell wall-associated protein; ENT: ear-nose-throat; ICU: intensive care units; OD: optical densities; PCR: polymerase chain reaction; SDS: sodium dodecyl sulfate; UTI: urinary tract infection.

Serotyping of Klebsiella pneumoniae and Its Relation with Capsule-Associated Virulence Genes, Antimicrobial Resistance Pattern, and Clinical Infections: A Descriptive Study in Medical Practice.

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.

Virulence characterization of Klebsiella pneumoniae and its relation with ESBL and AmpC beta-lactamase associated 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 ß-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.

Clostridium difficile in patients with nosocomial diarrhea, Northwest of Iran.

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.

Peptide nucleic acid-mediated re-sensitization of colistin resistance Escherichia coli KP81 harboring mcr-1 plasmid.

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.

Comparison of the disinfectant effects of Nanosil D2 and Korsolex extra solutions on thermoset acrylic resin contaminated with Streptococcus mutans and Bacillus subtilis.

This study was conducted to compare the disinfectant effects of Nanosil D2 and Korsolex extra on thermoset acrylic resin contaminated with Streptococcus mutans and Bacillus subtilis. In this experimental study, 90 acrylic samples were made and sterilized. Two samples were cultured as a sterilization control in brain-heart infusion (BHI) and the rest of samples were divided into two groups. Samples of one group were placed in a bacterial suspension of S. mutans and the samples of another group were placed in a suspension containing B. subtilis. Each group was divided into two subgroups for immersion in Nanosil or Korsolex extra solutions. Seven samples were selected from each group at each of 30 min, 1 h, and 2 h and transferred to the BHI test tube, and their turbidity was evaluated after 24 h. SPSS 17 software was used to analyze the data, and the significance level of test was considered P < 0.05. At 1 h, Bacillus level of Nanosil D2 was significantly lower than that of Korsolex extra, and at all ½, 1, and 2 h, the level of Streptococcus in Nanosil D2 solution was significantly lower than that of Korsolex extra (P < 0.05). Bacillus and Streptococcus levels showed significant reduction in both solutions over time. The disinfecting power of Nanosil D2 is more than that of Korsolex extra.

The Effect of Photodynamic Therapy and Casein Phosphopeptide-Amorphous Calcium Phosphate (CPP-ACP) on the Remineralization Rate of Non-Cavitated Root: an In-vitro Study.

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.

Disinfection effect of microwave radiation on Bacillus subtilis as indicator organism on contaminated dental stone casts under dry and wet conditions.

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<0.05). Conclusion: According to the results, microwave irradiation can disinfect dental stone casts to a high degree, irrespective of moisture level. However, the result should be confirmed by exploring with other species of resistant microorganisms.

nim gene-independent metronidazole-resistant Bacteroides fragilis in surgical site infections.

Background:Bacteroides fragilis is the most common anaerobic pathogen isolated from surgical site infections (SSIs). Metronidazole resistance is increasing and the mechanisms of resistance are not clear in some isolates. The aim of the present study was to investigate the metronidazole susceptibility prevalence, and detect nim genes in B. fragilis isolates from SSIs. Methods: This study included 100 surgery patients with signs and symptoms indicative of SSIs. Syringe aspiration of the infected site was used to collect specimens. All specimens were cultured on BBA (Brucella blood agar), KVLB (kanamycin-vancomycin laked blood), and BBE (Bacteroides bile esculin) agar. The MIC (minimum inhibitory concentration) of metronidazole was determined by the agar dilution method according to the Clinical and Laboratory Standard Institute (CLSI). Then the PCR method was used to determine the presence of the nim gene. Results: In the present study, 26 B. fragilis were isolated from 100 SSIs specimens. Eight isolates were metronidazole resistant; the metronidazole MIC was 32 µg/mL for 7 isolates and 64 µg/mL for one isolate. All isolates were nim gene negative. Conclusion: The emergence of metronidazole-resistant B. fragilis limits the application of this drug for treatment and prophylaxis of SSIs. Thus, rapid identification of metronidazole-resistant B. fragilis is essential to restrict inappropriate, superfluous administration. In spite of various metronidazole resistance mechanisms other than that depending on the nim gene, detection of nim by PCR is unsuitable for identifying resistant isolates. Therefore, phenotypic methods are better to screen for and identify metronidazole-resistant B. fragilis.

Role of Enterotoxigenic Bacteroides fragilis in Children Less Than 5 Years of Age With Diarrhea in Tabriz, Iran.

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.

Antibiotic Susceptibility Pattern of Aerobic and Anaerobic Bacteria Isolated From Surgical Site Infection of Hospitalized Patients.

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.

Antibiotic Sensitivity of Clostridium perfringens Isolated From Faeces in Tabriz, Iran.

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.

Bacterial etiology and antibiotic susceptibility pattern of diabetic foot infections in Tabriz, Iran.

AIM: The aim of this study was to investigate anaerobic and aerobic bacteria profile and determination of antibiotic susceptibility pattern in aerobic bacteria. METHOD: Specimens were cultured using optimal aerobic and anaerobic microbiological techniques. Identification of bacterial isolates was performed by standard microbiological methods and antibiotic susceptibility testing was performed according to the guidelines of Clinical and Laboratory Standards Institute (CLSI). RESULT: 92 bacterial strains were isolated from 60 samples of diabetic foot ulcers. Predominant aerobic bacteria isolated from these infections were S. aureus (28%) followed by Enterobacteriaceae family (24%) including Escherichia coli (15%), Citrobacter spp. (4%), Enterobacter spp. (4%), and coagulase-negative Staphylococcus spp. (17%), Enterococcus spp. (15%), Pseudomonas aeruginosa (7%) and Acinetobacter spp. (4%). No Clostridium spp. were isolated and 4% Bacteroides fragilis obtained from anaerobic culture. All Gram-positive isolates were susceptible to linezolid while all Enterobacteriaceae showed sensitivity to imipenem. CONCLUSION: Most of DFIs specimens were poly microbial infection and predominant bacteria were S. aureus and B. fragilis. These wounds may require use of combined antimicrobial therapy for initial management.

Detection, Virulence Gene Assessment and Antibiotic Resistance Pattern of O157 Enterohemorrhagic Escherichia coli in Tabriz, Iran.

BACKGROUND: Shiga toxin-producing Escherichia coli (STEC) is a food-borne pathogen and infection with this organism causes illnesses such as bloody diarrhea, hemorrhagic colitis and hemolytic-uremic syndrome. OBJECTIVES: Considering the lack of any information about the prevalence rate and the antibiotic resistance pattern of O157:H7 serotype in Tabriz, finding answers to the above mentioned subjects was among the goals of this study. MATERIALS AND METHODS: Two hundred E. coli strains from diarrheal or non-diarrheal stools of outpatients and hospitalized cases in Tabriz Imam Reza hospital were isolated between September and December 2014 using MacConkey agar and standard biochemical tests and then cultured on sorbitol MacConkey agar. The sorbitol-negative isolates were confirmed as the O157 serotype using O157 antisera. A multiplex polymerase chain reaction (PCR) method was used for the detection of stx-1, stx-2, eae, and mdh genes and the antibiotic resistance pattern of these isolates was determined using Kirby-Bauer method and clinical and laboratory standards institute (CLSI) standards. RESULTS: Of the isolates 11 (5.5%) were sorbitol-negative, which were later analyzed by multiplex PCR and the results revealed that 2 (18.18%) isolates contained the stx-1 gene, 10 (90.91%) contained the stx-2 gene, and 5 (45.45%) contained the eae gene. The stx-2 and eae genes were the most commonly encountered virulence factors. All or most of the isolates were susceptible to ceftazidime (100%), gentamicin (100%), ciprofloxacin (100%), nalidixic acid (90.9%), trimetoprim sulfamethoxazole (90.9%), chloramphenicol (90.9%), ampicillin (81.8%), and cephalothin (72.7%). On the contrary, moderate susceptibility of the isolates to doxycycline (54.5%) was observed. CONCLUSIONS: Due to the low frequency of STEC O157 and the high susceptibility rates of the isolates to the tested antibiotics in this study, STEC O157 has not become a major problem in Tabriz yet, but comprehensive microbiological surveillance programs that provide early warning and limit the scale of possible outbreaks would be essential.

Comparison of in vitro activities of meropenem productions on Klebsiella pneumoniae isolated from hospitalized patients.

PURPOSE: Antimicrobial activities of meropenem products on Klebsiella pneumoniae isolates were determined. METHODS: 212 non-duplicated Klebsiella pneumoniae isolates were examined for in vitro meropenem susceptibility test by using the following disks, which were made from Meronem (AstraZeneca, UK), Exipenem (Exir, Iran) and Meroxan (DAANA, Iran) powders. MIC50 and MIC90 for meropenem antibiotics were determined. RESULTS: Meronem had good activities against most isolates of Klebsiella pneumoniae, and only a few strains had a rather high MIC. Exipenem and Meroxan showed a similar activity with Meronem. CONCLUSION: Regarding the comparison of two internal generic meropenem products with the external Meronem product have shown that they are equivalents in terms of microbiological activity, as measured using the disk diffusion and MIC. In developing countries, we suggested preparing disks with antibiotic powders that can be an equivalent function in microbiological activity with standard disks. In addition, since it demonstrated significant antimicrobial activity against the Klebsiella pneumoniae. For use of Exipenem and Meroxan in vivo, it would be better to perform additional testing (activity against different species, stability etc.).