Role of gut microbiota in the pathogenesis of colorectal cancer; a review article

Colorectal cancer [CRC] is one of the most frequently diagnosed cancers worldwide. Lifestyle is identified as one of the most important risk factors for CRC, especially in sporadic colorectal cancer. The natural composition of the gut microbiota changes rapidly during the first decade of life. Maintaining homeostasis in the gut is essential as structural and metabolic functions of the commensal microbiota inhibit gut colonization of pathogens. Dysbiosis, imbalance in function or structure of gut microbiota, has been associated with a variety of diseases, such as colorectal cancer. The aim of this review was to investigate the possible links between the dysbiosis in gut microbiota and colorectal cancer, and the potential role of anaerobic gut microbiota in the pathogenesis of colorectal cancer. Based on this review, various studies have shown that some of the gut microbiota such as anaerobic bacteria significantly increased in CRC patients, but we suggest more investigations are required to assess the importance of these bacteria and their metabolites in the pathogenesis of CRC are required

Fecal microbiota transplantation for recurrent clostridium difficile infection in patients with inflammatory bowel disease; case series

Clostridium difficile infection in patients with inflammatory bowel disease [IBD] is associated with more severe disease, longer hospital admission, higher treatment costs, and higher risk of colectomy and mortality rate. The classic endoscopic view of the disease is adherent whitish-yellowish multifocal membrane, defined as "psudo-membrane". Using stool polymerase chain reaction [PCR] is the best way for identifying this organism. Patients with mild to moderate infection are treated with oral metronidazole, while severe infections are treated with oral vancomycin for 10 days. The first recurrence of clostridium difficile infection is treated with the same regimen as the initial episode; however the second recurrence is treated with vancomycin pulse therapy. In the third recurrence, fecal microbiota transplantation [FMT] is one of the treatment choices. This study is a report of three successful FMT in our patients

role of the intensive care unitenvironment and health-care workers inthe transmission of bacteria associatedwith hospital acquired infections

The goal of this study was to attempt to determine the rate of con-tamination of health-care workers' [HCWs] hands and environmental surfaces inintensive care units [ICU] by the main bacteria associated with hospital acquiredinfections [HAIs] in Tehran, Iran. A total of 605 and 762 swab samples wereobtained from six ICU environments and HCWs' hands. Identification of the bac-terial isolates was performed according to standard biochemical methods, andtheir antimicrobial susceptibility was determined based on the guidelines recom-mended by clinical and laboratory standards institute [CLSI]. The homology ofthe resistance patterns was assessed by the NTSYSsp software. The most frequent bacteria on the HCWs' hands and in the environmental samples were Acinetobac-ter baumannii [1.4% and 16.5%, respectively], Staphylococcus aureus [5.9% and 8.1%,respectively], S. epidermidis [20.9% and 18.7%, respectively], and Enterococcus spp.[1% and 1.3%, respectively]. Patients' oxygen masks, ventilators, and bed linens werethe most contaminated sites. Nurses' aides and housekeepers were the most contam-inated staff. Imipenem resistant A. baumannii [94% and 54.5%], methicillin-resistantS. aureus [MRSAs, 59.6% and 67.3%], and vancomycin resistant Enterococci [VREs, 0%and 25%] were detected on the hands of ICU staff and the environmental samples,respectively. Different isolates of S. aureus and Enterococcus spp. showed significanthomology in these samples. These results showed contamination of the ICU environ-ments and HCWs with important bacterial pathogens that are the main risk factorsfor HAIs in the studied hospitals

Comparison of antimicrobial susceptibility of Campylobacter strains isolated from food samples and patients with diarrhea

Background: Campylobacter infections may lead to serious conditions, including septicemia or other invasive forms of the disease, which require rapid and accurate laboratory diagnosis and subsequently appropriate antimicrobial therapy. The aim of this study was to compare the species distribution and antimicrobial susceptibility pattern of Campylobacter spp. strains isolated from patients and food samples

Methods: Biochemical identification was performed on 15 clinical and 30 food isolates of Campylobacter recovered onto Brucella agar containing 5% sheep blood. PCR was carried out to confirm the identity of Campylobacter spp. using primers for cadF, hipO, and asp genes of Campylobacter. To determine antibiotic sensitivity of isolates, Kirby- Bauer assay was carried out using 16 different antibiotic discs

Results: PCR assay and biochemical tests confirmed all 45 isolates as Campylobacter: 20 [44.44%] as C. jujeni, 10 [22.22%] as C. coli, and 15 [33.34%] as other Campylobacter strains. The maximum resistance was observed to cefotaxime and imipenem [each 86.49%] and the maximum sensitivity to erythromycin [48.65%]

Conclusion: C. jujeni is dominant among isolates from clinical and food samples. In addition, tetracycline remains the first-line therapeutic agent against Campylobacter infections in Iran

Isolation of atypical enteropathogenic and shiga toxin encoding Escherichia coli strains from poultry in Tehran, Iran

Aim: The purpose of this study was to investigate the prevalence of enteropathogenic Escherichia coli [EPEC] and shiga toxin producing E. coli [STEC] strains in healthy broilers in Iran

Background: STEC and EPEC strains as diarrheagenic E. coli are among the most prevalent causative agents in acute diarrhea. Domestic animals, mainly cattle and sheep, have been implicated as the principal reservoirs of these pathotypes; however their prevalence among the broilers is varied among different countries

Patients and methods: A total of 500 cloacal swab samples from broilers of five different poultry houses [A-E] were collected to investigate the presence of stx1, stx2, hly, eae, and bfp virulence genes among the E. coli isolates by polymerase chain reaction. The shiga toxin encoding strains were evaluated serologically to detect their interaction with a commercial antiserum against O157 antigen

Results: Out of the 500 collected samples, 444 E. coli strains were isolated. Three strains [0.67%] presented at least one of the studied virulence genes [stx2, hly and eae], two strains were identified as STEC [stx2+, O157:nonH7] and one as an atypical EPEC strains [eae[+]bfp[-]]

Conclusion: The study established the presence of STEC and atypical EPEC in healthy broilers in Iran. Poultry might serve as vectors for transmission of pathogenic E. coli to human populations

Dysbiosis of fecal microbiota and high frequency of citrobacter, klebsiella spp., and actinomycetes in patients with irritable bowel syndrome and gastroenteritis

Aim: This study was aimed to characterize putative differences of fecal microbiota between irritable bowel syndrome[IBS] and gastroenteritis patients and healthy controls

Background: New evidence proposed that gut microbiota has a deep effect on the balance between health and disease

Patients and methods: The presence of Clostridium difficile, Campylobacter spp., Enterobacteriacea and Staphylococci weredetected in the samples using selective and specific culture media. Microscopic examination of the samples was done to detectActinomycetes, yeasts, Bifidobacteria, Fusobacterium spp., as well as white blood cells, red blood cells, mucus and epithelial cells

Results: Results of this study showed relatively higher frequency of Citrobacter spp., Lactobacilli, and Actinomycetes in theIBS patients. Elevated levels of WBC, RBC secretion, and increased amounts of Klebsiella, Escherichia coli and Citrobacterspp. were characterized in the patients with gastroenteritis compared with the control group

Conclusion: Depletion of gram positive cocci and gram negative bacilli also suggested dysbiosis of intestinal microbiotain these patients

Influence of heat shock temperatures and fast freezing on viability of probiotic sporeformers and the issue of spore plate count versus true numbers

Background and Objectives: The purpose of the present study was to investigate effects of various heat shock conditions and fast freezing and subsequent thawing on the viability and recovery of Bacillus coagulans and Bacillus subtilis as probiotic Sporeformers, and also to compare spore plate and microscopic counts

Materials and Methods: After preparing the final suspensions of B. coagulans and Bacillus suhtilis subsp. Natto spores, they were spread-plated before and after fast freezing treatment [-70°C for about 1 min]. Heat shock treatments of the spores were carried out at 68°C for 15, 20, and 30 min as well as at 80°C for 10 and 15 min. Concentrations of the examined probiotic Sporeformers were determined simultaneously by plate enumerations and microscopically determined counts. Student's t-test and one-way analysis of variance [ANOVA] of SPSS were used for statistical analysis of the data. Analysis of DoE results was carried out using Minitab

Results: The results presented here show that the highest recovery rates for B. coagulans [14.75 log CFU/mL] and B. subtilis spores [14.80 log CFU/mL] were under a heat shock condition of 68°C for 20 min in nutrient agar [p<0.05]

In addition, the survival rates of B. coagulans and B. subtilis spores under the fast freezing and subsequent thawing condition were about 90% and 88%, respectively. Plate counts differed significantly from counts determined microscopically, with differences of almost 0.5 and 0.8 log for B. coagulans and B. subtilis spores, respectively [p<0.05]

In addition, DoE results of the study revealed that both factors of spore count method and only freezing factor in fast freezing treatment have a significant effect on concentrations of the spores examined [p<0.05]

Conclusions: Heat shock conditions, freezing and subsequent thawing circumstances, and plate counts or enumerations determined microscopically have significant influences on the viability of probiotic Sporeformers and should be considered in determining of their accurate concentrations

Association of tcdA[+]/tcdB[+] clostridium difficile genotype with emergence of multidrug-resistant strains conferring metronidazole resistant phenotype

Reduced susceptibility of Clostridium difficile to antibiotics is problematic in clinical settings. There is new evidence indicating the cotransfer of toxin-encoding genes and conjugative transposons encoding resistance to antibiotics among different C. difficile strains. To analyze this association, in the current study, we evaluated the frequency of toxigenic C. difficile among the strains with different multidrug-resistant [MDR] profiles in Iran. Antimicrobial susceptibility patterns and minimal inhibitory concentrations [MIC] of the isolates were determined against metronidazole, imipenem, ceftazidime, amikacin, and ciprofloxacin by agar dilution method. The association of the resistance profiles and toxigenicity of the strains were studied by PCR targeting tcdA and tcdB genes. Among 86 characterized strains, the highest and lowest resistance rates were related to ciprofloxacin [97%] and metronidazole [5%], respectively. The frequency of resistance to other antibiotics was as follow: imipenem [48%], ceftazidime [76%], and amikacin [76.5%]. Among the resistant strains, double drug resistance and MDR phenotypes were detected in the frequencies of 10.4% and 66.2%, respectively. All of the metronidazole-resistant strains belonged to tcdA [+]/tcdB[+] genotype with triple or quintuple drug resistance phenotypes. MIC[50] and MIC[90] for this antibiotic was equally

Device-associated infection rates and bacterial resistance in six academic teaching hospitals of Iran: Findings from the International Nocosomial Infection Control Consortium [INICC]

Device-associated health care-acquired infections [DA-HAIs] pose a threat to patient safety, particularly in the intensive care unit [ICU]. However, few data regarding DA-HAI rates and their associated bacterial resistance in ICUs from Iran are available. A DA-HAI surveillance study was conducted in six adult and pediatric ICUs in academic teaching hospitals in Tehran using CDC/NHSN definitions. We collected prospective data regarding device use, DA-HAI rates, and lengths of stay from 2584 patients, 16,796 bed-days from one adult ICU, and bacterial profiles and bacterial resistance from six ICUs. Among the DA-HAIs, there were 5.84 central line-associated bloodstream infections [CLABs] per 1000 central line-days, 7.88 ventilator-associated pneumonias [VAPs] per 1000 mechanical ventilator-days and 8.99 catheter-associated urinary tract infections [CAUTIs] per 1000 urinary catheter-days. The device utilization ratios were 0.44 for central lines, 0.42 for mechanical ventilators and 1.0 for urinary catheters. The device utilization ratios of mechanical ventilators and urinary catheters were higher than those reported in the ICUs of the INICC and the CDC's NHSN reports, but central line use was lower. The DA-HAI rates in this study were higher than the CDC's NHSN report. However, compared with the INICC report, the VAP rate in our study was lower, while the CLAB rate was similar and the CAUTI rate was higher. Nearly 83% of the samples showed a mixed-type infection. The most frequent pathogens were Acinetobacter baumannii,Staphylococcus aureus and Pseudomonas aeruginosa, followed by Klebsiella pneumoniae andEnterococcus spp. In the S. aureus isolates, 100% were resistant to oxacillin. Overall resistances of A. baumannii and K. pneumonia to imipenem were 70.5% and 76.7%, respectively. A multiple drug resistance phenotype was detected in 68.15% of the isolates. The DA-HAI rates in Iran were shown to be higher than the CDC-NHSN rates and similar to the INICC rates. Resistance to oxacillin and imipenem was higher as well. Comparing device use, DA-HAI rates, and bacterial resistance for the primary isolated bacteria indicated a direct association between urinary catheter use and the rates of CAUTI

Genotyping of echinococcus gtanulosus isolates from human clinical samples based on sequencing of mitochondrial genes in Iran, Tehran

The present study was aimed to investigate molecular diversity of Echinococcus gmnulosus isolates collected from human clinical samples using two mitochondrial genes cox1 and nod1 in Iran. Forty seven human hydatid cysts were collected through surgery from two hospitals in Tehran during 2010-2012. To determine the fertility of protoscoleces, the cyst fluids were subjected to morphological microscopic examinations. Protoscoleces were removed from each cyst and their total genomic DNAs were extracted. PCR was performed to amplify fragments of 450 and 400 base pair [bp] for cox1 and nod1 genes, respectively. Genotype diversity and sequence variation of the strains were studied by bioinformatics software and in comparison with those mtDNA sequences already dposited in GenBank. Sixteen, [53.3%], 13 [43.3%], and 1 [3.3%] samples were related to lung, liver, and spleen, respectively. The remained 17 unfertile samples were excluded from the study. From the 29 isolates, 86.7% [n=26] and 10% [n=3] were related to G1, and G3 genotypes, respectively. The sole isolate with G6 genotype was obtained from lung sample. Analysis of concatenated sequences of cox1+nad1 indicated the presence of 11 haplotypes among our strains that were related to genotypes G1 [n=9], G3 [n=1] and G6 [n=1]. In consistent to other reports from Iran, genotypes G1, G3, and G6 were observed in our human isolates. The rate of G3 genotype was however higher than other studies implying that human can be considered as a new appropriate host for G3 genotype. Further studies with more sample size from different geographic areas of Iran are needed for E. granulosus mapping

Fecal carriage of Escherichia coli and Klebsiella spp. as major reservoirs of clinically important resistance markers

Intestinal normal flora can become reservoirs of antibiotic resistance genes present among the strains responsible for nosocomial infections. It is suggested that gram negative intestinal bacterial flora have increased capacities to obtain antibiotic resistance genes and therefore can act as main reservoirs for transfer of resistance genes to other pathogenic bacteria. This study aimed to compare fecal carriage of clinically important resistance markers for more frequent members of enterobacteriacae between nondiarrheal and community associated diarrheal patients [control group] versus their counterparts from the patients with nosocomial infections [case group]. 261 stool and 190 clinical samples were collected from outpatient and hospitalized patients from 6 hospitals in Tehran, Iran. The samples were cultured on MacConkey agar plates and colonies were identified by standard biochemical methods. Antibiotic sensitivity testing of the isolates against 13 antibiotics was performed according to the CLSI guideline using the disk diffusion method. Among stool and clinical samples, more frequent identified enterobacteriaceae bacteria were included E. coli [58.99/ 3.15%], Klebsiella spp. [22.61/7.36%], and other members of enterobacteriaceae [8.86/1.06%], respectively. Overall, resistance against four of the main antibiotics [3[th] and 4[th] generation cephalosporins, gentamicin, imipenem, and ciprofloxacin] was significantly higher among the case group [50-75% versus 10-14%]. Analysis of these results showed similar dissemination of resistance phenotypes among the isolates from the control group in ranges of 1.5-7.6% and 4.4% for E. coli and Klebsiella spp., respectively. Our results suggested that the fecal carriage of resistant phenotypes related to the beta-lactam antibiotics in E. coli and Klebsiella spp. in compare to the clinical isolates is rapidly increasing. This may be caused by dissemination of beta-lactamase producing E. coli in the community from the hospitals. There were no significant correlations between the two groups of the samples, as the clinical samples had shown 3 to 7 folds excess resistance phenotypes. Surveillance studies of the resistance patterns among the samples from different regions will provide awareness about dissemination of these bacteria within the community as reservoirs of main resistance markers