Silje Bakken Jørgensen

High rate of per oral mecillinam treatment failure in community-acquired urinary tract infections caused by ESBL-producing Escherichia coli.

A population-based study was performed to investigate the efficacy of mecillinam treatment of community-acquired urinary tract infections (CA-UTI) caused by extended-spectrum β-lactamase (ESBL) producing Escherichia coli. The study was conducted in South-Eastern Norway. Data from patients with CA-UTI caused by ESBL-producing and non-producing (random controls) E. coli were collected through interviews, questionnaires, medical records and the Norwegian Prescription Database. Treatment failure was defined as a new antibiotic prescription appropriate for UTI prescribed within two weeks after the initial antimicrobial therapy. Multivariable logistic regression analysis was performed to identify treatment agents and patient- or bacterial traits associated with treatment failure. A total of 343 patients (mean age 59) were included, of which 158 (46%) were treated with mecillinam. Eighty-one patients (24%, mean age 54) had infections caused by ESBL producing E. coli, and 41 of these patients (51%) received mecillinam as the primary treatment. Mecillinam treatment failure was observed in 18 (44%) of patients infected by ESBL-producing strains and in 16 (14%) of patients with a CA-UTI caused by ESBL non-producing strains. Multivariable analysis showed that ESBL status (odds ratio (OR) 3.2, 95% confidence interval (CI) 1.3–7.8, p = 0.009) and increased MIC of mecillinam (OR 2.0 for each doubling value of MIC, CI 1.4–3.0, p<0.001) were independently associated with mecillinam treatment failure. This study showed a high rate of mecillinam treatment failure in CA-UTIs caused by ESBL producing E. coli. The high failure rate could not be explained by the increased MIC of mecillinam alone. Further studies addressing the use of mecillinam against ESBL-producing E. coli, with emphasis on optimal dosing and combination therapy with β-lactamase inhibitors, are warranted.

High prevalence of faecal carriage of ESBL-producing Enterobacteriaceae in Norwegian patients with gastroenteritis

Abstract We conducted a cross-sectional study to examine the prevalence of faecal carriage of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae in patients with gastroenteritis. During April 2011, all faecal samples submitted to our hospital laboratory were examined for ESBL-producing Enterobacteriaceae. Isolates expressing an ESBL phenotype were investigated for the presence of genes encoding broad-spectrum beta-lactamases, ESBLs, carbapenemases, and plasmid-mediated AmpC. Information on age, gender, and travel history was extracted from the laboratory records. In total 273 faecal samples were included. The overall carrier rate in the study population was 15.8%. The ESBL carrier rate among patients with no history of recent travel, or where this information was missing, was 10.3%. In contrast, the carrier rate was 56.3% (odds ratio 16.3, p < 0.001) among patients with a record of travel to Asia. Two ESBL-producing isolates were identified as enteropathogenic Escherichia coli. Co-resistance between third-generation cephalosporins, trimethoprim–sulfamethoxazole, and fluoroquinolones was seen in 49% of isolates. No carbapenemase-producers were found.

Anaerobic blood culture isolates in a Norwegian university hospital: identification by MALDI‐TOF MS vs 16S rRNA sequencing and antimicrobial susceptibility profiles

We investigated 197 anaerobic isolates recovered from blood cultures in the period 2009–2013. The isolates included were Bacteroides spp., Clostridium spp., Prevotella spp., Fusobacterium spp. and Gram‐positive anaerobic cocci (GPAC). Identification results by MALDI‐TOF MS were compared to those obtained by 16S rRNA sequencing, and the MICs of benzylpenicillin, clindamycin, piperacillin‐tazobactam, meropenem and metronidazole were determined by Etests. The MALDI‐TOF MS correctly identified 94.9% of the anaerobes to the genus level, and 86.8% to the species level, with errors mainly among the non‐fragilis Bacteroides spp. and GPAC. About 73.3% of the isolates were non‐susceptible to penicillin, mainly due to high resistance rates in the Bacteroides spp. (99.2%) and Prevotella spp. (69.2%). About 18.5% of the isolates were clindamycin resistant. Piperacillin‐tazobactam had an excellent activity against all anaerobes except the non‐fragilis Bacteroides spp., of which 43.8% were non‐susceptible. The clinical significance of such a high resistance rate is unclear. Meropenem and metronidazole were the most active antibiotics, with 96.9% and 97.9% of the isolates being susceptible.

Fecal carriage of extended spectrum β-lactamase producing Escherichia coli and Klebsiella pneumoniae after urinary tract infection – A three year prospective cohort study

We have performed a prospective cohort study to investigate the duration of and risk factors for prolonged fecal carriage of ESBL-producing Escherichia coli or Klebsiella pneumoniae in patients with community acquired urinary tract infection caused by these bacteria. From 2009 to 2011, 101 Norwegian patients were recruited. Stool swabs and questionnaires were collected every three months for one year and at the end of the study in 2012. Information on antibiotic prescriptions was collected from the Norwegian Prescription Database. Stool samples were cultured directly on ChromID ESBL agar as well as in an enrichment broth, and culture positive isolates were examined by blaCTX-M multiplex PCR. Isolates without blaCTX-M were investigated for alternative ESBL-determinants with a commercial microarray system. Time to fecal clearance of ESBL producing Enterobacteriaceae was also analysed using Kaplan-Meier estimates. Uni- and multivariate logistic regression was used to compare groups according to previously described risk factors. The ESBL point prevalence of fecal carriage were 61% at 4 months, 56% at 7 months, 48% at 10 months, 39% at 13 months, 19% after two years, and 15% after three years or more. We found no correlation between duration of carriage, comorbidity, antibiotic use or travel to ESBL high-prevalence countries. Prolonged carriage was associated with E. coli isolates of phylogroup B2 or D. Importantly, comparative MLST and MLVA analyses of individual paired urine and fecal E. coli isolates revealed that ESBL production commonly occurred in diverse strains within the same host. When investigating cross-transmission of ESBL producing bacteria in health care institutions, this notion should be taken into account.

Anti-pertussis antibody kinetics following DTaP-IPV booster vaccination in Norwegian children 7–8 years of age

At the age of 7-8 years a booster of diphtheria, tetanus, acellular pertussis and polio vaccine is recommended for children in Norway. In this cross-sectional study we have analysed the antibody levels against pertussis vaccine antigens in sera from 498 children aged 6-12 years. The purposes of this study were to investigate the duration of the booster response against the pertussis vaccine antigens pertussis toxin (PT) and filamentous haemagglutinin (FHA); to determine the presence of high levels of pertussis antibodies in absence of recent vaccination; and to analyse how booster immunisation may interfere with the serological pertussis diagnostics. Prior to the booster the IgG antibody levels against PT revealed a geometric mean of 7.3IU/ml. After the booster the geometric mean peak anti-PT IgG response reached to 45.6IU/ml, followed by a steady decline in antibody levels over the next few years. The IgG anti-FHA levels followed the anti-PT IgG profiles. Three years after the booster the geometric mean IgG levels were only slightly above pre-booster levels. Prior to the booster 44% of the sera contained ≤5IU/ml of anti-PT IgG compared to18% 3 years after and 30% 4 years after the booster. When recently vaccinated children were excluded, 6.2% of the children had anti-PT IgG levels above 50IU/ml which may indicate pertussis infection within the last 2 years. This study indicates that the currently used acellular pertussis vaccines induce moderate immune responses to the pertussis antigens and that the antibodies wane within few years after the booster. This lack of sustained immune response may partly be responsible for the increased number of pertussis cases observed in this age group during the last years.

First environmental sample containing plasmid-mediated colistin-resistant ESBL-producing Escherichia coli detected in Norway

We hereby report the detection of the plasmid borne mcr‐1 gene conferring colistin resistance in an extended‐spectrum β‐lactamase (ESBL) producing Escherichia coli ST10 strain retrieved from seawater at a public beach in Norway. The sample was collected in September 2010 and was investigated by whole‐genome sequencing in 2016. This report illustrates that E. coli strains carrying plasmid‐mediated colistin resistance genes have also reached areas where this drug is hardly used at all. Surveillance of colistin resistance in environmental, veterinary, and human strains is warranted also in countries where colistin resistance is rare in clinical settings.

A comparison of extended spectrum β-lactamase producing Escherichia coli from clinical, recreational water and wastewater samples associated in time and location

Extended spectrum β-lactamase producing Escherichia coli (ESBL-EC) are excreted via effluents and sewage into the environment where they can re-contaminate humans and animals. The aim of this observational study was to detect and quantify ESBL-EC in recreational water and wastewater, and perform a genetic and phenotypic comparative analysis of the environmental strains with geographically associated human urinary ESBL-EC. Recreational fresh- and saltwater samples from four different beaches and wastewater samples from a nearby sewage plant were filtered and cultured on differential and ESBL-selective media. After antimicrobial susceptibility testing and multi-locus variable number of tandem repeats assay (MLVA), selected ESBL-EC strains from recreational water were characterized by whole genome sequencing (WGS) and compared to wastewater and human urine isolates from people living in the same area. We detected ESBL-EC in recreational water samples on 8/20 occasions (40%), representing all sites. The ratio of ESBL-EC to total number of E. coli colony forming units varied from 0 to 3.8%. ESBL-EC were present in all wastewater samples in ratios of 0.56–0.75%. ST131 was most prevalent in urine and wastewater samples, while ST10 dominated in water samples. Eight STs and identical ESBL-EC MLVA-types were detected in all compartments. Clinical ESBL-EC isolates were more likely to be multidrug-resistant (p<0.001). This study confirms that ESBL-EC, including those that are capable of causing human infection, are present in recreational waters where there is a potential for human exposure and subsequent gut colonisation and infection in bathers. Multidrug-resistant E. coli strains are present in urban aquatic environments even in countries where antibiotic consumption in both humans and animals is highly restricted.

Implications of stx loss for clinical diagnostics of Shiga toxin-producing Escherichia coli

The dynamics related to the loss of stx genes from Shiga toxin-producing Escherichia coli remain unclear. Current diagnostic procedures have shortcomings in the detection and identification of STEC. This is partly owing to the fact that stx genes may be lost during an infection or in the laboratory. The aim of the present study was to provide new insight into in vivo and in vitro stx loss in order to improve diagnostic procedures. Results from the study support the theory that loss of stx is a strain-related phenomenon and not induced by patient factors. It was observed that one strain could lose stx both in vivo and in vitro. Whole genome comparison of stx-positive and stx-negative isolates from the same patient revealed that different genomic rearrangements, such as complete or partial loss of the parent prophage, may be factors in the loss of stx. Of diagnostic interest, it was shown that patients can be co-infected with different E. coli pathotypes. Therefore, identification of eae-positive, but stx-negative isolates should not be interpreted as “Shiga toxin-lost” E. coli without further testing. Growth and recovery of STEC were supported by different selective agar media for different strains, arguing for inclusion of several media in STEC diagnostics.

Genotypic characterization of gentamicin and cephalosporin resistant Escherichia coli isolates from blood cultures in a Norwegian university hospital 2011–2015

BackgroundCephalosporin resistance in clinical E. coli isolates is increasing internationally. The increase has been caused by virulent and often multidrug-resistant clones, especially the extended spectrum β-lactamase (ESBL) producing E. coli clone O25b-ST131.MethodsIn Norway, recommended empirical treatment of sepsis consists of gentamicin and penicillin combined, or a broad-spectrum cephalosporin. To investigate if increased gentamicin and cephalosporins resistance rates in our hospital could be caused by specific clones, we conducted a retrospective study on E. coli blood culture isolates from 2011 through 2015. All E. coli isolates non-susceptible to gentamicin and/or third-generation cephalosporins were genotyped using multiple-locus variable-number of tandem repeat analysis (MLVA) and compared with antibiotic susceptible isolates. The frequency of the most common genes causing ESBL production (blaCTX-M, blaampC) was examined by Real-Time PCR.ResultsA total of 158 cephalosporin and/or gentamicin resistant and 97 control isolates were differentiated into 126 unique MLVA types. Of these, 31% of the isolates belonged to a major MLVA cluster consisting of 41% of the gentamicin resistant and 35% of the cephalosporin resistant isolates. The majority (65/80 isolates) of this MLVA cluster contained MLVA types associated with the E. coli O25b-ST131 clone. Genes encoding CTX-M enzyme phylogroups 1 and 9 occurred in 65% and 19% of cephalosporin resistant isolates, respectively, whereas blaampC-CIT was identified in 3%.ConclusionNo local E. coli bacteraemia clone was identified. Antibiotic resistance was dispersed over a variety of genotypes. However, association with the international E. coli O25b-ST131 clone was frequent and may be an important driver behind increased resistance rates. Monitoring and preventing dissemination of these resistant clones are important for continued optimal treatment.