Development and clinical validation of a molecular diagnostic assay to detect CTX-M-type beta-lactamases in Enterobacteriaceae.
Enterobacterial isolates producing CTX-M beta-lactamases have recently emerged worldwide in the community and hospital settings. Because of the significant public health implications, the spread of organisms producing CTX-M enzymes merits close monitoring with enhanced surveillance efforts. A molecular diagnostic assay using two different sets of primers simultaneously for the detection of all bla(CTX-M)-like beta-lactamase genes was developed. This assay repeatedly demonstrated 100% sensitivity, specificity and positive and negative predictive values for detecting different CTX-M enzymes in well-characterised strains that included producers of VEB-, TEM- and SHV-type extended-spectrum beta-lactamases (ESBLs) and plasmid-mediated AmpC enzymes. The majority (132/240; 55%) of ESBL-producing enterobacterial isolates recovered in the Calgary Health Region during 2003 and 2004 were positive for bla(CTX-M) genes, including 81 (61%) positive for the CTX-M-9 group, 49 (37%) for the CTX-M-1 group, and two (2%) for the CTX-M-2 group. The CTX-M-specific PCR assay was reproducible and easy to use. It can be introduced in a clinical or reference laboratory to track and monitor the spread of organisms producing CTX-M enzymes in the community and hospital settings.
Pitout
J D D
JD
Division of Microbiology, Calgary Laboratory Services, Calgary, Alberta, Canada. johann.pitout@cls.ab.ca
Hamilton
N
N
Church
D L
DL
Nordmann
P
P
Poirel
L
L
D004755:Enterobacteriaceae / Q000201:enzymology*; D006801:Humans; D007525:Isoelectric Focusing; D016133:Polymerase Chain Reaction; D001618:beta-Lactamases / Q000235:genetics*
C071167:beta-lactamase CTX-2; C055184:beta-lactamase TEM-3; D001618:beta-Lactamases