Community and hospital spread of Escherichia coli producing CTX-M extended-spectrum beta-lactamases in the UK.

Abstract

OBJECTIVES:

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.

• Authors: N Woodford, M E Ward, M E Kaufmann, J Turton, E J Fagan, D James, A P Johnson, R Pike, M Warner, T Cheasty, A Pearson, S Harry, J B Leach, A Loughrey, J A Lowes, R E Warren, D M Livermore
• Journal: The Journal of antimicrobial chemotherapy (J Antimicrob Chemother) Vol. 54 Issue 4 Pg. 735-43 (Oct 2004) ISSN: 0305-7453 [Print] England
• PMID: 15347638 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Anti-Bacterial Agents
• beta-Lactamases

Topics

• Alleles
• Anti-Bacterial Agents (pharmacology)
• Community-Acquired Infections (epidemiology, microbiology)
• Conjugation, Genetic
• Cross Infection (epidemiology, microbiology)
• Drug Resistance, Bacterial (genetics)
• Electrophoresis, Gel, Pulsed-Field
• Escherichia coli (drug effects, enzymology, genetics, isolation & purification)
• Escherichia coli Infections (epidemiology, microbiology)
• Genes, Bacterial (genetics)
• Humans
• Microbial Sensitivity Tests
• Phenotype
• United Kingdom (epidemiology)
• beta-Lactamases (biosynthesis, genetics)