NDM carbapenemases in the United Kingdom: an analysis of the first 250 cases.
OBJECTIVE
Gram-negative bacteria with diverse carbapenemases, including New Delhi metallo-β-lactamase (NDM) enzymes, have been increasingly recorded in the UK since 2007. We analysed patient data for NDM-positive isolates confirmed by the national reference laboratory from UK laboratories from February 2008 to July 2013.


METHODS
Isolates resistant to carbapenems and with imipenem MICs reduced ≥8-fold by EDTA were tested by PCR for genes encoding acquired class B carbapenemases. MICs were determined by BSAC agar dilution methodology. When requested by the sender, or when they were members of apparent clusters, NDM-positive isolates were typed by variable number tandem repeat (VNTR) analysis or PFGE. Data provided by the sending laboratories were collated and reviewed.


RESULTS
From February 2008 to July 2013 the reference laboratory confirmed 326 NDM-positive isolates from 250 patients, submitted by 83 laboratories. Most (85%, 213/250) patients were already hospitalized when the NDM-positive bacteria were detected, were male (61%, 152/250) and were aged >60 years (58%, 145/250). Travel history was available for only 40% of patients, but 52% (53/101) of these had documented healthcare contact within or travel to the Indian subcontinent. Most NDM-positive isolates (94%, 306/326) were Enterobacteriaceae with just 6% (20/326) non-fermenters; the predominant hosts were Klebsiella spp. (55%, 180/326) and Escherichia coli (25%, 80/326). Almost all NDM-positive isolates were resistant to multiple antibiotic classes, but 90% remained susceptible to colistin.


CONCLUSIONS
Gram-negative bacteria with NDM carbapenemases are a growing challenge, especially for elderly hospitalized patients, including those with healthcare contact in the Indian subcontinent, and leave few therapeutic options. UK outbreaks remain rare and contained.
Antimicrobial Resistance and Healthcare Associated Infections Reference Unit, Public Health England, London NW9 5EQ, UK.
Anu
A
Jain
Antimicrobial Resistance and Healthcare Associated Infections Reference Unit, Public Health England, London NW9 5EQ, UK.
Katie L
KL
Hopkins
Antimicrobial Resistance and Healthcare Associated Infections Reference Unit, Public Health England, London NW9 5EQ, UK.
Jane
J
Turton
Antimicrobial Resistance and Healthcare Associated Infections Reference Unit, Public Health England, London NW9 5EQ, UK.
Michel
M
Doumith
Antimicrobial Resistance and Healthcare Associated Infections Reference Unit, Public Health England, London NW9 5EQ, UK.
Robert
R
Hill
Antimicrobial Resistance and Healthcare Associated Infections Reference Unit, Public Health England, London NW9 5EQ, UK.
Richard
R
Loy
Antimicrobial Resistance and Healthcare Associated Infections Reference Unit, Public Health England, London NW9 5EQ, UK.
Daniele
D
Meunier
Antimicrobial Resistance and Healthcare Associated Infections Reference Unit, Public Health England, London NW9 5EQ, UK.
Rachel
R
Pike
Antimicrobial Resistance and Healthcare Associated Infections Reference Unit, Public Health England, London NW9 5EQ, UK Norwich Medical School, University of East Anglia, Norwich NR4 7TJ, UK.
David M
DM
Livermore
Antimicrobial Resistance and Healthcare Associated Infections Reference Unit, Public Health England, London NW9 5EQ, UK neil.woodford@phe.gov.uk.
Neil
N
Woodford
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D015780:Carbapenems / Q000494:pharmacology*; D005260:Female; D006090:Gram-Negative Bacteria / Q000145:classification / Q000187:drug effects* / Q000201:enzymology* / Q000302:isolation & purification; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D006113:United Kingdom; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism*
D001426:Bacterial Proteins; D015780:Carbapenems; D001618:beta-Lactamases; C063912:carbapenemase
Acinetobacter; Enterobacteriaceae; MBLs; Pseudomonas; meropenem