Cefotaxime-resistant Enterobacteriaceae isolates from a hospital in Warsaw, Poland: identification of a new CTX-M-3 cefotaxime-hydrolyzing beta-lactamase that is closely related to the CTX-M-1/MEN-1 enzyme.
A group of cefotaxime-resistant Citrobacter freundii and Escherichia coli isolates were collected by a clinical laboratory in a hospital in Warsaw, Poland, in July 1996. Detailed analysis has shown that all of these produced a beta-lactamase (pI, 8.4) belonging to the CTX-M family, one of the minor extended-spectrum beta-lactamase families with a strong cefotaxime-hydrolyzing activity. Sequencing has revealed that C. freundii isolates produced a new CTX-M-3 enzyme which is very closely related to the CTX-M-1/MEN-1 beta-lactamase, sporadically identified in Europe over a period of 6 years. Amino acid sequences of these two beta-lactamases differ at four positions: Val77Ala, Asp114Asn, Ser140Ala, and Asn288Asp (the first amino acid of each pair refers to CTX-M-1/MEN-1 and second refers to CTX-M-3). The partial sequence of the E. coli CTX-M gene was identical to the corresponding region of bla(CTX-M-3), but a transconjugant of the E. coli isolate expressed higher levels of resistance to beta-lactams than did C. freundii transconjugants. These resistance differences correlated with differences in plasmid DNA restriction patterns. Our results suggest that CTX-M genes have been spread among different species of the family Enterobacteriaceae in the hospital and that the CTX-M-3-expressing C. freundii strain causing routine urinary tract infections has been maintained for a relatively long time in the hospital environment.
Gniadkowski
M
M
Sera and Vaccines Central Research Laboratory, Warsaw, Poland. marekg@ibbrain.ibb.waw.pl
Schneider
I
I
Pałucha
A
A
Jungwirth
R
R
Mikiewicz
B
B
Bauernfeind
A
A
D000595:Amino Acid Sequence; D001483:Base Sequence; D002439:Cefotaxime / Q000494:pharmacology*; D018550:Cephalosporin Resistance; D002511:Cephalosporins / Q000494:pharmacology*; D004269:DNA, Bacterial / Q000032:analysis; D004755:Enterobacteriaceae / Q000187:drug effects* / Q000235:genetics; D004756:Enterobacteriaceae Infections / Q000235:genetics / Q000382:microbiology*; D006801:Humans; D007525:Isoelectric Focusing; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010957:Plasmids / Q000187:drug effects / Q000235:genetics; D011044:Poland; D016133:Polymerase Chain Reaction; D001618:beta-Lactamases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
D002511:Cephalosporins; D004269:DNA, Bacterial; D001618:beta-Lactamases; D002439:Cefotaxime