Abstract Book of EAVLD2012 - eavld congress 2012

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CHARACTERIZATION OF EXTENDED-SPECTRUM ß-LACTAMASE (ESBL)-PRODUCING
ESCHERICHIA COLI BOVINE ISOLATES IN NORTHWEST SPAIN.
V. Gómez 1,2 , A. Mora 2 , A. Méndez 1 , R. Mamani 2 , C. López 2 , A. Lamas 1 , C. Eiras 1 , J. Blanco 2
1 Laboratorio de Sanidade e Produción Animal de Galicia, Consellería do Medio Rural e do Mar, Xunta de Galicia, Lugo, España
2
Departamento de Microbioloxía e Parasitoloxía. Laboratorio de Referencia de Escherichia coli. Facultade de Veterinaria. USC, Lugo, España
Keyword: Escherichia coli, ESBLs, bovine, CTX-M
Introduction
Extended-spectrum ß-lactamases (ESBLs) confer bacterial
resistance to all beta-lactams except carbapenems and
cephamycins. In 1989, a new family of ESBLs called CTX-M
was characterized with a potent hydrolytic activity against
cephalosporins such as cefuroxime, cefotaxime and cefepime.
At least 65 ß-lactamases CTX-M are currently known and
spread all over the world (1).
The emergence and wide dissemination of ESBLs among
clinical Escherichia coli (E. coli) isolates in hospitals,
community patients, food-producing animals and household
pets in recent years are of great concern and represent a
problem for the treatment of infectious diseases (2).
The aim of this study was the genotypic and phenotypic
characterization of E. coli strains isolated from bovine.
3. Locatelli C, Caronte I, Scaccabarozzi L, Migliavacca R, Pagani L,
Moroni P. 2009. Extended-spectrum β-lactamase production in E. coli
strains isolated from clinical bovine mastitis. Vet. Res. Commun. 33:
141-144.
4. López-Cerero L, Egea P, Serrano L, Navarro D, Mora A, Blanco J,
Doi Y, Paterson DL, Rodríguez-Baño J, Pascual A. Characterisation of
clinical and food animal Escherichia coli isolates producing CTX-M-15
extended-spectrum β-lactamase belonging to ST410 phylogroup A. Int J
Antimicrob Agents. 2011 Apr;37(4):365-7. Epub 2011 Feb 16. PubMed
PMID: 21330111.
5. Cortés P, Blanc V, Mora A, Dahbi G, Blanco JE, Blanco M, López C,
Andreu A, Navarro F, Alonso MP, Bou G, Blanco J, Llagostera M.
Isolation and characterization of potentially pathogenic antimicrobialresistant
Escherichia coli strains from chicken and pig farms in Spain.
Appl Environ Microbiol. 2010 May;76(9):2799-805. Epub 2010 Mar 12.
PubMed PMID: 20228098; PubMed Central PMCID: PMC2863447.
Material and Methods
From 2003 to 2009, 38 strains of ESBL-producing E. coli were
isolated from clinical cases of bovine mastitis and diarrhoea
from dairy farms in Galicia, northwest Spain.
The phenotypic characterization was determined by BD
PhoenixTM Automated Microbiology System and double-disk
synergy test.
Genotypic ESBL confirmation, virulence gene, phylogenetic
groups, and amplification of fragment blaCTX-M were carried
out by PCR. Finally, the strains were serotyped, and molecular
characterized by multilocus sequence typing (MLST) and
pulsed-field gel electrophoresis (PFGE).
Results
Analysis of the 38 isolates showed that 74% (28 strains) and
26% (10 strains) produced CTX-M-14 and CTX-M-32
enzymes, respectively. A statistical significant association was
found between CTX-M-14 and resistance to gentamicin, and
CTX-M-32 and resistance to aztreonam and ceftazidime. Of
the 38 E. coli isolates, 30 (79%) carried at least two virulence
gene typical of extraintestinal pathogenic E. coli strains
(ExPEC).
The determination of phylogenetic groups showed that the E.
coli isolates belonged to A (50%), B1 (31.5%) and D (18.4%)
phylogroups. None of the bovine isolates belonged to the
phylogenetic group B2 associated with human virulence in
ExPEC.
In accordance with the high diversity identified by serotyping,
PFGE molecular analysis revealed highly heterogeneous
profiles. Only one successful clonal group, the O20:H8/HNT-
B1-ST448 CTX-M-14-producing, was detected.
Discussion & conclusions
Our survey demonstrates that Galician bovine is a reservoir of
CTX-M-14 and CTX-M-32-producing E. coli strains, with
important associated resistances to aminoglycoside,
tetracycline, sulphonamide, fluoroquinolone and
chloramphenicol.
Although person-to person spread is recognised as the main
vehicle of spread of ESBL-producing E. coli in hospital and
the community, the primary reservoirs of such organisms are
still in discussion. ESBL-producing E. coli have been isolated
from food animals in many countries, particularly poultry and
cattle (3, 4, 5), so farm animals are now recognised as
important carriers of BLEEs. Further studies are required to
determine the true zoonotic potential of these ESBL-producing
strains.
References
1. Cantón R, Coque TM. 2006. The CTX-M beta-lactamase pandemic.
Curr. Opin. Microbiol. 9:466-475.
2. Carattoli A. 2008. Animal reservoirs for extended-spectrum ß-
lactamase producers. Clin. Microbiol. Infect. 14:117-123.