Molecular and epidemiological characterization of carbapenemase-producing Enterobacteriaceae in Norway, 2007 to 2014

Source at https://doi.org/10.1371/journal.pone.0187832 The prevalence of carbapenemase-producing Enterobacteriaceae (CPE) is increasing worldwide. Here we present associated patient data and molecular, epidemiological and phenotypic characteristics of all CPE isolates in Norway from 2007 to 2014 confirmed at the Norwegian National Advisory Unit on Detection of Antimicrobial Resistance. All confirmed CPE isolates were characterized pheno- and genotypically, including by whole genome sequencing (WGS). Patient data were reviewed retrospectively. In total 59 CPE isolates were identified from 53 patients. Urine was the dominant clinical sample source (37%) and only 15% of the isolates were obtained from faecal screening. The majority of cases (62%) were directly associated with travel or hospitalization abroad, but both intra-hospital transmission and one inter-hospital outbreak were observed. The number of CPE cases/year was low (2–14 cases/year), but an increasing trend was observed. Klebsiella spp. (n = 38) and E. coli (n = 14) were the dominant species and blaKPC (n = 20), blaNDM (n = 19), blaOXA-48-like (n = 12) and blaVIM (n = 7) were the dominant carbapenemase gene families. The CPE isolates were genetically diverse except for K. pneumoniae where clonal group 258 associated with blaKPC dominated. All isolates were multidrug-resistant and a significant proportion (21%) were resistant to colistin. Interestingly, all blaOXA-48-like, and a large proportion of blaNDM-positive Klebsiella spp. (89%) and E. coli (83%) isolates were susceptible in vitro to mecillinam. Thus, mecillinam could have a role in the treatment of uncomplicated urinary tract infections caused by OXA-48- or NDM-producing E. coli or K. pneumoniae. In conclusion, the impact of CPE in Norway is still limited and mainly associated with travel abroad, reflected in the diversity of clones and carbapenemase genes

Cluster of linezolid-resistant Enterococcus faecium ST117 in Norwegian hospitals

A linezolid-resistant, vancomycin-susceptible Enterococcus faecium strain was isolated from 3 patients who had not received linezolid. The first patient was hospitalized in the same hospitals and wards as the 2 following patients. The E. faecium isolates were resistant to linezolid (minimum inhibitory concentration 8–32 mg/l), ampicillin, and high levels of gentamicin. Resistance to linezolid was associated with a G2576T mutation in 23S rDNA. The cfr linezolid resistance gene was not detected. The 3 isolates showed identical DNA fingerprints by pulsed-field gel electrophoresis, belonged to ST117, and harboured virulence genes esp, hyl, acm, efaAfm, srgA, ecbA, scm, pilA, pilB, and pstD typically associated with high-risk E. faecium genotypes. The linezolid-resistant E. faecium high-risk clone caused bacteraemia in the first 2 cancer patients and survived in the hospital environment for more than a year before appearing in the urethral catheter of the third patient

Time-line and distribution of identified CPEs and carbapenemase variants.

<p>No. of isolates in parenthesis.</p

Phylogenetic tree of <i>K</i>. <i>pneumoniae</i> isolates based on alignment of concatenated sequences of the 694 cgMLST scheme of <i>K</i>. <i>pneumoniae</i> [22].

<p>The tree was constructed in RAxML [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0187832#pone.0187832.ref049" target="_blank">49</a>] and visualized using FigTree (<a href="http://tree.bio.ed.ac.uk/software/figtree/" target="_blank">http://tree.bio.ed.ac.uk/software/figtree/</a>). Clonal groups with >1 isolates are boxed. Sequence type (ST), carbapenemase gene and year of isolation is indicated for each isolate. Isolates associated with the long-term outbreak [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0187832#pone.0187832.ref050" target="_blank">50</a>] and the two occurrences of intra-hospital transmission are labelled *, # and ¤, respectively.</p

Antimicrobial resistance profiles of CPE isolates according to species and carbapenemase variant.

<p>Antimicrobial resistance profiles of CPE isolates according to species and carbapenemase variant.</p

Dissemination and Characteristics of a Novel Plasmid-Encoded Carbapenem-Hydrolyzing Class D β-Lactamase, OXA-436, Found in Isolates from Four Patients Involving Six Different Hospitals in Denmark.

The diversity of OXA-48-like carbapenemases are continually expanding. In this study, we describe the dissemination and characteristics of a novel class D carbapenemase (CHDL) named OXA-436. In total, six OXA-436-producing Enterobacteriaceae isolates including Enterobacter asburiae (n=3), Citrobacter freundii (n=2) and Klebsiella pneumoniae (n=1) were identified in four patients in the period between September 2013 and April 2015. One patient carried all three species of OXA-436-producing Enterobacteriaceae. Epidemiological investigation revealed extensive patient transfer between hospitals and the involvement of six hospitals altogether. The amino acid sequence of OXA-436 showed 90.4-92.8% identity to other acquired OXA-48-like variants. Expression of OXA-436 in Escherichia coli and kinetic analysis of purified OXA-436 revealed an activity profile similar to OXA-48 and OXA-181 with activity against penicillins including temocillin, limited or no activity against extended-spectrum cephalosporins and activity against carbapenems. The blaOXA-436 gene was located on a conjugative ~314 kb IncHI2/IncHI2A plasmid belonging to pMLST ST1, in a sequence region surrounded by chromosomal genes previously identified adjacent to blaOXA-genes in Shewanella spp. In conclusion, OXA-436 is a novel CHDL with similar functional properties as OXA-48-like CHDLs. The described geographical spread among different Enterobacteriaceae and plasmid location of blaOXA-436 illustrates its potential of further dissemination