Prevalence and epidemiological investigation of mgrB-dependent colistin resistance in extensively drug resistant Klebsiella pneumoniae in Iran.

Carbapenemases-producing K. pneumoniae are challenging antimicrobial therapy of hospitalised patients, which is further complicated by colistin resistance. The aim of this study was to investigate the molecular epidemiological insights into carbapenemases-producing and colistin-resistant clinical K. pneumoniaeA total of 162 colistin resistant clinical strains of K. pneumoniae were collected during 2017-2019. Antimicrobial susceptibility and the colistin minimum inhibitory concentration were determined. Using PCR assay, the prevalence of resistance-associated genes including blaKPC, blaIMP, blaVIM, blaOXA-48, blaNDM-1 and mcr-1 to -9 was examined. Additionally, a PCR assay was used to examine the mgrB gene in colistin-resistant bacteria. 94.4% of the tested strains were resistant to imipenem and 96.3% were resistant to meropenem. Colistin resistance (MIC > 4 µg/L) was observed in 161 isolates (99.4%) by Colistin Broth Disk Elution method. The KPC enzyme was the most common carbapenemase and was identified in 95 strains (58.6%), followed by the IMP, VIM and OXA-48 detected in 47 (29%), 23 (14.2%) and 12 (7.4%) isolates, respectively. However, no NDM-1 gene was detected. Additionally, none of the studied isolates harbored mcr variants, while mgrB gene was observed in 152 (92.6%) isolates. Colistin resistance of K. pneumoniae isolates may be associated with mgrB gene mutation. To stop the spread of resistant K. pneumoniae, surveillance must be improved, infection prevention protocols must be followed, and antibiotic stewardship must be practised.

Carriage of CdtB Encoding Campylobacter spp., Salmonella enterica, and Yersinia entercolitica in Patients with Gastroenteritis and Irritable Bowel Syndrome.

INTRODUCTION: Cytolethal distending toxin (Cdt) is one of the bacterial toxins that present in a variety of gram-negative human pathogens, such as E. coli, Salmonella spp., and Campylobacter spp. CDT is composed of three subunits encoded by three adjacent genes, including cdtA, cdtB, and cdtC. cdtB has been shown to have toxic activity and cause DNA damage in host cells. Despite its presence in different bacterial species, the role of CdtB in acute and chronic infections, such as gastroenteritis and irritable bowel syndrome (IBS), is unclear. To analyze this correlation, we studied the prevalence of cdtB among different enteropathogenic bacteria in patients with gastroenteritis and IBS compared with healthy people. MATERIALS AND METHODS: In this cross-sectional descriptive study, 230 stool samples were collected from patients with gastroenteritis, IBS, and healthy people. The presence of CdtB encoding bacteria, including Escherichia coli, Campylobacter spp., Yersinia entercolitica, Providencia alkalifacience, and Salmonella enterica, was examined by polymerase chain reaction using genus-specific primers. RESULTS: Out of 230 stool samples, CdtB encoding Campylobacter spp. were found in 34.6% (52/150), 6.25% (5/80), and 4% (2/50) of the patients with gastroenteritis, IBS, and the control group, respectively. Carriage of CdtB encoding Salmonella enterica was characterized among 5.3% (8/150) of the patients with gastroenteritis and 17.5% (14/80) of the IBS patients. Although none of the patients carried CdtB encoding E. coli and Providencia spp., cdtB of Y. enterocolitica was detected in one of the patients with gastroenteritis (0.6%). Statistical analysis showed significant correlation between infection with CdtB encoding Campylobacter spp. and IBS-D subtype. No significant correlation was found between infection with CdtB encoding bacteria and other clinical and demographic data. CONCLUSION: Our results confirmed a relatively higher frequency of CdtB encoding bacteria in the intestine of patients with gastroenteritis and those with IBS compared with healthy individuals. Regarding the frequency of CdtB encoding Salmonella and Campylobacter bacteria, it was proposed that infection with these enteropathogens could be considered a risk factor for the development or progression of IBS among Iranian patients. Further studies are needed to establish this involvement.

Prevalence, species diversity, and antimicrobial susceptibility of Campylobacter strains in patients with diarrhea and poultry meat samples: one-year prospective study.

Background and Objectives: Source tracking of antimicrobial resistance in Campylobacter is useful for control measures. In this study, Campylobacter-associated diarrhea and homology in antimicrobial resistance of humans and poultry meat isolates were investigated. Materials and Methods: A total of 400 stools of patients and 100 poultry meat samples were analyzed. Susceptibility of the isolates was detected by disk diffusion, Etest, and agar dilution methods. Mismatch amplification mutation assay was used for the detection of mutations in the gyrA quinolone resistance determining region (QRDR). Results: Campylobacter spp., including C. jejuni, C. coli, and C. lari, were detected in 35% of the chicken meat and 6.75% of the stool samples, respectively. The QRDR mutation was detected in most of the stool and chicken meat samples. Although the frequency of resistance to tetracycline (53.5% and 62.8%), erythromycin (39.2% and 37.1%), and gentamicin (32.1% and 31.4%) was relatively similar, higher frequency of resistance to ciprofloxacin (51.4% vs 28.6%) and nalidixic acid (42.15% vs 28.6%) among the chicken meat, and ampicillin (50% and 17.1%) among the human stool was detected. Conclusion: High percentage of poultry meat samples is contaminated with different Campylobacter species, which shows homology with the patients' isolates in Tehran.

Shiga toxin-producing bacteria as emerging enteric pathogens associated with outbreaks of foodborne illness in the Islamic Republic of Iran.

BACKGROUND: Detection of the cause of diarrhoeal diseases is important for the management of the outbreaks. AIMS: This study investigated the prevalence of Shiga toxin-producing bacteria in stool samples of patients with diarrhoea associated with outbreaks of foodborne illness in the Islamic Republic of Iran. METHODS: A total of 532 stool and rectal swab samples from 70 sporadic outbreaks during May 2014 to August 2015 were examined for infection with Shiga toxin-producing bacteria. The isolates were examined for carriage of the virulence genes stx1 and stx2 in all isolates and eae/ehxA in Escherichia coli. RESULTS: E. coli, Shigella spp., Citrobacter spp., Enterobacter spp., Klebsiella spp. and other enteric bacteria were detected in 77.7% (376/484), 5.0% (24/484), 3.9% (19/484), 0.4% (2/484), 3.7% (18/484) and 9.3% (45/484) of the samples respectively. Of the 196 sorbitol-negative E. coli strains, 3 (1.5%) carried the stx1 gene as did 2 of the 19 (10.5%) Citrobacter strains. CONCLUSION: Shiga toxin-producing Citrobacter spp. strains should be considered as a newly emerging foodborne pathogen in outbreaks.

Comparative transcriptional analysis for Toll-like receptors, inflammatory cytokines, and apoptotic genes in response to different cytolethal-encoding and noncoding isolates of Salmonella enterica and Campylobacter jejuni from food and human stool.

Diversity of Campylobacter and Salmonella strains in interaction with epithelial cells may explain distinct modes of the pathogenesis, varying from mild watery to severe inflammatory diarrhea. We analyzed impact of this diversity, in relation to carriage and expression of cytholethal distending toxin B (cdtB), on alteration of IL-8, TNF-α, TLR2, TLR4, TLR5, CASP3 mRNA and cytokine levels in HT-29 cell line. A diversity was observed for induction of genes among different strains. Great diversity in IL-8 induction was detected between cdtB+ and cdtB- strains. Early analysis showed down-regulation of TNF-α, mostly among cdtB+ strains. Any increase or decrease in expression of TLR2 in the cdtB-C. jejuni strains was orderly correlated with increase or decrease of TLR4 and TNF-α. Up-regulation of CASP3 was followed by upregulation of TLR2, -4 and/or TNF-α, regardless to the cdtB status. In conclusion, induction of inflammatory response could mediate by distinct C. jejuni and S. enterica strains by several ways.

The Diagnostic Tests for Detection of Helicobacter pylori Infection.

Helicobacter pylori causes one of the most common infections in human populations. The role of this bacterium in chronic gastritis, gastric ulcer, gastric cancer, as well as extra-digestive diseases such as ischemic heart disease and chronic obstructive pulmonary diseases, is well known. Prevention and control of these diseases can occur by early diagnosis and eradication of H. pylori infection. At present, different methods have been established to detect H. pylori infection. The biopsy-based tests, which are known as invasive methods, such as rapid urease test and histology, have the highest specificity among the others. Similarly, culture of biopsy samples is used for diagnosis of H. pylori infection. It has a high specificity value, and also allows us to perform antibiotic sensitivity testing. On the contrary, polymerase chain reaction and other molecular methods have good sensitivity and specificity, and can be used for detection of H. pylori infection, its virulence factors, and eradication success after treatment. While serological tests are more appropriate for epidemiological studies, their main weakness for clinical use is low specificity. Overall, specificity and sensitivity, cost, usefulness, and limitation of tests should be considered for selection of detection methods of H. pylori in each country.

Colonization, resistance to bile, and virulence properties of Escherichia coli strains: Unusual characteristics associated with biliary tract diseases.

Escherichia coli is the species that is most frequently isolated from bile of patients with biliary tract diseases. This study was aimed to investigate any association between resistance and virulence properties of these isolates with occurrence of the diseases. A total of 102 bile samples were obtained from patients subjected to endoscopic retrograde cholangiopancreatography for different biliary diseases. Clinical data were collected and culture of the bile samples was done on selective media. Resistance of characterized Escherichia coli isolates to deoxycholate sodium (0-7%) and nineteen antibiotics was determined and PCR using 16 pairs of primers targeting stx1, stx2, exhA, eae, bfp, agg, pcvd432, lt, st, ipaH, pic, pet, ast, set, sen, and cdtB genes was done. Our results showed a statistically significant association between E. coli colonization and existence of common bile duct and gallbladder stones (p value 0.028). Out of the 22 E. coli strains (22/102) multidrug resistance phenotype was present in 95.45%. None of the strains belonged to common E. coli pathotypes. However, bfp + EhxA-hly, bfp + astA, bfp + EhxA-hly + pic, and EhxA-hly + pic + astA, bfp, and astA genotypes were detected in these strains. bfp (7/22, 31.8%) and astA (5/22, 22.7%) were among most frequent virulence factors in these strains. Results of this study showed significant association between colonization of E. coli and choledocholithiasis. Unusual existence of virulence gene combinations in these strains and their resistance to DOC and multiple classes of antibiotics could be considered as possible causes of their persistence in this harsh microenvironment.

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 were detected in the samples using selective and specific culture media. Microscopic examination of the samples was done to detect Actinomycetes, 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 the IBS patients. Elevated levels of WBC, RBC secretion, and increased amounts of Klebsiella, Escherichia coli and Citrobacter spp. 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 microbiota in these patients.