Surveillance of extended-spectrum beta-lactamases from clinical samples and faecal carriers in Barcelona, Spain.
OBJECTIVE
The aim of the present study was to characterize and compare the extended-spectrum beta-lactamase (ESBL)-producing organisms isolated from clinical samples and faecal carriers in 2001 and 2002.


METHODS
A total of 5251 Enterobacteriaceae isolated from clinical samples and 1321 stool samples were evaluated for the presence of ESBLs. The stool samples were spread onto plates of MacConkey agar containing 2 mg/L cefotaxime for selection of ESBL-producing strains. These strains were defined as those showing synergism between amoxicillin/clavulanic acid and third-generation cephalosporins. The beta-lactamases involved were characterized by isoelectric focusing, PCR assays and DNA sequencing.


RESULTS
The prevalence of ESBL-producing strains among clinical Enterobacteriaceae was 1.7%. Of these, 87.6% produced CTX-M, 25.8% produced SHV and 2.2% were TEM-type-producing strains. All clinical ESBL-producing strains were Escherichia coli, with the exception of four Klebsiella pneumoniae and one Citrobacter freundii. The prevalence of faecal carriage of ESBL-producing organisms was 3.3%. Of these, 75% produced CTX-M-type enzymes followed by 22.7% SHV-producing strains. All faecal ESBL-producing strains were E. coli except for one Enterobacter cloacae and one Proteus mirabilis. This latter strain produced the PER-1 enzyme reported for the first time in Spain.


CONCLUSIONS
The prevalence of ESBL-producing strains in stool samples was higher than that observed in clinical samples from the same period. The different types of ESBLs found were similar in both contexts. The most prevalent ESBLs were the CTX-M-related enzymes, with nine different types, followed by SHV-12.
Miró
Elisenda
E
Servei de Microbiologia de l'Hospital de la Santa Creu i Sant Pau, Barcelona, Spain.
Mirelis
Beatriz
B
Navarro
Ferran
F
Rivera
Alba
A
Mesa
Raúl Jesús
RJ
Roig
Ma Carme
MC
Gómez
Laura
L
Coll
Pere
P
D002353:Carrier State / Q000382:microbiology*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004755:Enterobacteriaceae / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D004756:Enterobacteriaceae Infections / Q000382:microbiology*; D005243:Feces / Q000382:microbiology*; D006801:Humans; D007525:Isoelectric Focusing; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013030:Spain; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000235:genetics* / Q000302:isolation & purification
D004269:DNA, Bacterial; D001618:beta-Lactamases