BackgroundShiga toxin-producing E. coli (STEC) infection is associated with haemolytic uremic syndrome (HUS). Therefore Norway has implemented strict guidelines for prevention and control of STEC infection. However, only a subgroup of STEC leads to HUS. Thus, identification of determinants differentiating high risk STEC (HUS STEC) from low risk STEC (non-HUS STEC) is needed to enable implementation of graded infectious disease response.MethodsA national study of 333 STEC infections in Norway, including one STEC from each patient or outbreak over two decades (1992–2012), was conducted. Serotype, virulence profile, and genotype of each STEC were determined by phenotypic or PCR based methods. The association between microbiological properties and demographic and clinical data was assessed by univariable analyses and multiple logistic regression models.ResultsFrom 1992 through 2012, an increased number of STEC cases including more domestically acquired infections were notified in Norway. O157 was the most frequent serogroup (33.6 %), although a decrease of this serogroup was seen over the last decade. All 25 HUS patients yielded STEC with stx2, eae, and ehxA. In a multiple logistic regression model, age ≤5 years (OR = 16.7) and stx2a (OR = 30.1) were independently related to increased risk of HUS. eae and hospitalization could not be modelled since all HUS patients showed these traits. The combination of low age (≤5 years) and the presence of stx2a, and eae gave a positive predictive value (PPV) for HUS of 67.5 % and a negative predictive value (NPV) of 99.0 %. SF O157:[H7] and O145:H?, although associated with HUS in the univariable analyses, were not independent risk factors. stx1 (OR = 0.1) was the sole factor independently associated with a reduced risk of HUS (NPV: 79.7 %); stx2c was not so.ConclusionsOur results indicate that virulence gene profile and patients’ age are the major determinants of HUS development.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-015-1017-6) contains supplementary material, which is available to authorized users.

Our results provide support for the hypothesis that clonal transfer of cephalosporin-resistant E. coli from chicken meat to humans may occur, and may cause difficult-to-treat infections. Furthermore, these E. coli can be a source of AmpC-resistance plasmids for opportunistic pathogens in the human microbiota.

The mechanisms for the development and spread of antibacterial resistance (ABR) in bacteria residing in environmental compartments, including the marine environment, are far from understood. The objective of this study was to examine the ABR rates in Escherichia coli and other Enterobacteriaceae isolates obtained from marine bivalve mollusks collected along the Norwegian coast during a period from October 2014 to November 2015. A total of 549 bivalve samples were examined by a five times three tube most probable number method for enumeration of E. coli in bivalves resulting in 199 isolates from the positive samples. These isolates were identified by biochemical reactions and matrix Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry, showing that 90% were E. coli, while the remaining were species within the genera Klebsiella, Citrobacter, and Enterobacter. All 199 isolates recovered were susceptibility tested following the European Committee on Antimicrobial Susceptibility Testing disk diffusion method. In total, 75 of 199 (38%) isolates showed resistance to at least one antibacterial agent, while multidrug-resistance were seen in 9 (5%) isolates. One isolate conferred resistance toward 15 antibacterial agents. Among the 75 resistant isolates, resistance toward extended-spectrum penicillins (83%), aminoglycosides (16%), trimethoprim (13%), sulfonamides (11%), tetracyclines (8%), third-generation cephalosporins (7%), amphenicols (5%), nitrofurans (5%), and quinolones (5%), were observed. Whole-genome sequencing on a selection of 10 E. coli isolates identified the genes responsible for resistance, including blaCTX-M genes. To indicate the potential for horizontal gene transfer, conjugation experiments were performed on the same selected isolates. Conjugative transfer of resistance was observed for six of the 10 E. coli isolates. In order to compare E. coli isolates from bivalves with clinical strains, multiple-locus variable number tandem repeats analysis (MLVA) was applied on a selection of 30 resistant E. coli isolates. The MLVA-profiles were associated with community-acquired E. coli strains causing bacteremia. Our study indicates that bivalves represent an important tool for monitoring antibacterial resistant E. coli and other members of the Enterobacteriaceae family in the coastal environment.

The expanding global distribution of multi-resistant Klebsiella pneumoniae demands faster antimicrobial susceptibility testing (AST) to guide antibiotic treatment. Current ASTs rely on time-consuming differentiation of resistance and susceptibility after initial isolation of bacteria from a clinical specimen. Here we describe a flow cytometry workflow to determine carbapenem susceptibility from bacterial cell characteristics in an international K. pneumoniae isolate collection (n = 48), with a range of carbapenemases. Our flow cytometry-assisted susceptibility test (FAST) method combines rapid qualitative susceptible/non-susceptible classification and quantitative MIC measurement in a single process completed shortly after receipt of a primary isolate (54 and 158 minutes respectively). The qualitative FAST results and FAST-derived MIC (MICFAST) correspond closely with broth microdilution MIC (MICBMD, Matthew’s correlation coefficient 0.887), align with the international AST standard (ISO 200776-1; 2006) and could be used for rapid determination of antimicrobial susceptibility in a wider range of Gram negative and Gram positive bacteria.

BackgroundAsymptomatic carriage has been recognised as an important risk factor for infection caused by antibiotic resistant bacteria. A 14% global prevalence of Extended-Spectrum Beta-lactamase (ESBL) carriage was recently reported, but large intra-and interregional variations were observed. We investigated the faecal carriage rates of ESBL-, AmpC-producing and ciprofloxacin non-susceptible Escherichia coli and Klebsiella spp. in healthy Norwegians.MethodsRectal samples were obtained from 284 volunteers, together with demographic data and information on recent travel history. The rectal samples were screened by selective plating and E. coli and Klebsiella spp. identified using MALDI-TOF. Phenotypic and molecular characterization of resistant isolates was also performed.ResultsESBL- or AmpC-producing E. coli and Klebsiella spp. were isolated from 4.9% and 3.2% of the study population, respectively. Carriage of ciprofloxacin non-susceptible isolates was detected in 9.9% of the volunteers. Molecular typing of ESBL/plasmid-mediated AmpC (pAmpC)-producing isolates suggested an allodemic situation rather than the dissemination of a specific clone in the Norwegian community. In concurrence with previous findings, travel to South-East Asia was associated with increased risk of carrying resistant E. coli or Klebsiella spp., highlighting the contribution of factors such as increased global mobility in erasing the boundaries between healthcare and community settings when it comes to spread of resistant bacteria.ConclusionsOverall, our study recognised Norway as a low-incidence country for faecal carriage of resistant bacteria among healthy individuals. Furthermore, our work denoted the importance of healthy humans as a reservoir for transmission of antibiotic resistant E. coli and Klebsiella spp.Electronic supplementary materialThe online version of this article (doi:10.1186/s13756-016-0156-x) contains supplementary material, which is available to authorized users.