Community and hospital spread of Escherichia coli producing CTX-M extended-spectrum beta-lactamases in the UK.
OBJECTIVE
During 2003, the Health Protection Agency's Antibiotic Resistance Monitoring and Reference Laboratory began to receive isolates of Escherichia coli for confirmation of extended-spectrum beta-lactamase production with a phenotype implying a CTX-M-type beta-lactamase, i.e. MICs of cefotaxime > or = 8-fold higher than MICs of ceftazidime. Many were referred as being from community patients. We examined 291 CTX-M-producing isolates from the UK and investigated the genetic basis of their phenotype.


METHODS
PCR was used to detect alleles encoding CTX-M enzymes and to assign these to their blaCTX-M phylogenetic groups. Selected alleles were sequenced. Producers were compared by analysis of banding patterns generated by pulsed-field gel electrophoresis of XbaI-digested genomic DNA. MICs were determined by an agar dilution method or by Etest.


RESULTS
Of 291 CTX-M-producing E. coli isolates studied from 42 UK centres, 70 (24%) were reportedly from community patients, many of whom had only limited recent hospital contact. Community isolates were referred by 12 centres. Two hundred and seventy-nine (95.9%) producers contained genes encoding group 1 CTX-M enzymes and 12 contained blaCTX-M-9-like alleles. An epidemic CTX-M-15-producing strain was identified, with 110 community and inpatient isolates referred from six centres. Representatives of four other major strains also produced CTX-M-15, as did several sporadic isolates examined. Most producers were multi-resistant to fluoroquinolones, trimethoprim, tetracycline and aminoglycosides as well as to non-carbapenem beta-lactams.


CONCLUSIONS
CTX-M-producing E. coli are a rapidly developing problem in the UK, with CTX-M-15 particularly common. The diversity of producers and geographical scatter of referring laboratories indicates wide dissemination of blaCTX-M genes. Because of the public health implications, including for the treatment of community-acquired urinary tract infections, the spread of these strains--and CTX-M-15 beta-lactamase in particular--merits close monitoring.
Woodford
N
N
Antibiotic Resistance Monitoring and Reference Laboratory, Specialist and Reference Microbiology Division-Colindale, Health Protection Agency, London. neil.woodford@hpa.org.uk
Ward
M E
ME
Kaufmann
M E
ME
Turton
J
J
Fagan
E J
EJ
James
D
D
Johnson
A P
AP
Pike
R
R
Warner
M
M
Cheasty
T
T
Pearson
A
A
Harry
S
S
Leach
J B
JB
Loughrey
A
A
Lowes
J A
JA
Warren
R E
RE
Livermore
D M
DM
D000483:Alleles; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D017714:Community-Acquired Infections / Q000453:epidemiology / Q000382:microbiology; D003227:Conjugation, Genetic; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology / Q000235:genetics* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000453:epidemiology* / Q000382:microbiology; D005798:Genes, Bacterial / Q000235:genetics; D006801:Humans; D008826:Microbial Sensitivity Tests; D010641:Phenotype; D006113:United Kingdom / Q000453:epidemiology; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000235:genetics
D000900:Anti-Bacterial Agents; D001618:beta-Lactamases