Involvement of Pseudomonas aeruginosa in the occurrence of community and hospital acquired diarrhea, and its virulence diversity among the stool and the environmental samples.

Transmission of Pseudomonas aeruginosa along the food chain could cause gastrointestinal infections. To show this involvement, the prevalence, putative virulence genotype, and antibiotic resistance phenotype of P. aeruginosa isolates from stool of 1482 patients with community and hospital acquired diarrhea were compared with 87 isolates from the environmental samples. The results showed infection with P. aeruginosa in 3.4% of the cases, while 57.4% of vegetable samples were contaminated. Significantly higher frequency of lasB (98%), aprA (98%), exoY (98%), and exoS (90%), but lower rate of exoT (39.2%), was detected among the stool isolates. Multi-drug resistance (MDR) phenotype was detected in 25.5% and 4% of the stool and vegetable isolates, respectively. A higher rate of studied virulence genes was detected among the MDR strains vs non-MDR strains. These results indicate P. aeruginosa as a causative agent of diarrhea either among the hospitalized patients and those with community-acquired diarrhea.

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.

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.

Emergence of blaCTX-M-15, blaTEM-169 and blaPER-1 extended-spectrum ß-lactamase genes among different Salmonella enterica serovars from human faecal samples.

BACKGROUND: Broad-spectrum ß-lactams are used for empirical therapy of severe infections with non-typhoid Salmonella serotypes; however, activities of these drugs against the strains producing different ß-lactamase is not so clear. This study investigated the prevalence of ß-lactamase genes among isolates of S. enterica serovars from human faecal samples and determined their diversity in activity against different ß-lactams. METHODS: Antimicrobial resistance of faecal isolates of S. enterica to extended-spectrum cephalosporins was analysed and MIC values were determined for the strains presenting extended-spectrum ß-lactamases (ESBLs) phenotypes. The ß-lactamase genes were identified by PCR and sequencing. ß-lactamase activity of the Salmonella strains exhibiting ESBL phenotype was detected by biological, iodometric, spectrophotometry and nitrocefin assays. RESULTS: Out of 202 S. enterica isolates, ESBLs phenotype was detected among 3.4% (7/202) of the strains. blaTEM-1 and blaCTX-M-15 were among the frequent ß-lactamase genes. Detection of blaTEM-169 in S. enterica serovar Typhimurium and S. enterica serovar Bredeney and blaPER-1 in S. enterica serovar Infantis was a new finding in this experiment. Location of blaCTX-M-15/blaTEM-169/blaPER-1 genes on plasmid was confirmed in a transformation experiment. While crude extracts of the enzymes from each strain showed higher activity against cephalothin and cefotaxime, the lowest activity was detected against ceftazidime. The greatest synergistic activity was seen in a strain of S. enterica that carried blaCTX-M-15 and blaPER-1 genes compared with those presenting blaCTX-M-15/blaTEM-169 or blaCTX-M-15/blaTEM-1 genotypes. CONCLUSIONS: The results show dissemination of ESBLs encoding genes and their combined activity among different serovars of S. enterica that are a threat for future treatment options.

The role of the intensive care unit environment and health-care workers in the transmission of bacteria associated with hospital acquired infections.

The goal of this study was to attempt to determine the rate of contamination of health-care workers' (HCWs) hands and environmental surfaces in intensive care units (ICU) by the main bacteria associated with hospital acquired infections (HAIs) in Tehran, Iran. A total of 605 and 762 swab samples were obtained from six ICU environments and HCWs' hands. Identification of the bacterial isolates was performed according to standard biochemical methods, and their antimicrobial susceptibility was determined based on the guidelines recommended by clinical and laboratory standards institute (CLSI). The homology of the resistance patterns was assessed by the NTSYSsp software. The most frequent bacteria on the HCWs' hands and in the environmental samples were Acinetobacter 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 were the most contaminated sites. Nurses' aides and housekeepers were the most contaminated staff. Imipenem resistant A. baumannii (94% and 54.5%), methicillin-resistant S. 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 significant homology in these samples. These results showed contamination of the ICU environments and HCWs with important bacterial pathogens that are the main risk factors for HAIs in the studied hospitals.

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 and Enterococcus 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.

Lack of association between Helicobacter pylori infection and biliary tract diseases.

There are ambiguous results about the involvement of Helicobacter species in production of hepatobiliary diseases. This study was aimed to investigate any possible association between the presences of Helicobacter spp., their genotypes and occurrence of different biliary diseases. Cultures of 102 bile samples for Helicobacter spp. did not show any growth, but the presence of Helicobacter genus specific DNA (16s rRNA gene) was detected in 3.92% of them. No significant association was found between development of the diseases and presence of the bacteria. All the Helicobacter genus positive samples belonged to H. pylori species and showed vacA+ (s1/m2), cagA- genotypes.