title: Detection of plasmid-borne extended-spectrum β-lactamase (ESBL) genes in Escherichia coli isolates from bovine mastitis.
abstract: Extended-spectrum β-lactamase (ESBL)-producing isolates have been increasingly reported during recent years. The aims of this study were to characterize ESBL-producing Escherichia coli from bovine mastitis as well as their ESBL gene-carrying plasmids. A culture collection of E. coli isolated from bovine quarter milk samples (2009-2013), was screened for ESBL production using ESBL selective agar plates. Putative ESBL producers (n=16) were investigated by phenotypic confirmatory tests and were characterized by the detection/sequencing of ESBL genes, XbaI macrorestriction analysis, multilocus sequence typing (MLST), phylotyping and antimicrobial susceptibility testing. ESBL gene-carrying plasmids were investigated by transfer experiments, PCRs for the detection of co-located antimicrobial resistance genes, PCR-based replicon typing and S1-nuclease pulsed-field gel electrophoresis. Twelve ESBL-producing isolates were found. They showed eleven different XbaI patterns and were distributed among eight MLST types [ST10 (n=3), ST117 (n=2), ST361 (n=1), ST362 (n=1), ST540 (n=1), ST1431 (n=2), ST1508 (n=1), and the novel ST5447 (n=1)] and the phylogenetic groups A (n=6), B1 (n=2), B2 (n=1) and D (n=3). ESBL genes blaCTX-M-1(n=5), blaCTX-M-2(n=2), blaCTX-M-14and blaCTX-M-15(n=4) were found on conjugative plasmids (35-225kb) of diverse incompatibility groups (e.g. IncF, IncI1 or HI2+P). Co-located resistance to sulfonamides, tetracycline, trimethoprim, and chloramphenicol/florfenicol was detected on five ESBL gene-carrying plasmids, but seven plasmids conferred solely resistance to β-lactam antibiotics. The presence of additional resistance genes on the ESBL gene-carrying plasmids suggests that co-selection of ESBL genes may occur even in the absence of β-lactam antibiotics.
authors: Institute of Farm Animal Genetics, Friedrich-Loeffler-Institut (FLI), Neustadt-Mariensee, Germany; Landesuntersuchungsamt Rheinland-Pfalz, Koblenz, Germany.
authors: Christin
authors: C
authors: Freitag
authors: Institute of Farm Animal Genetics, Friedrich-Loeffler-Institut (FLI), Neustadt-Mariensee, Germany. Electronic address: geovana.brenner@fli.de.
authors: Geovana Brenner
authors: GB
authors: Michael
authors: Institute of Farm Animal Genetics, Friedrich-Loeffler-Institut (FLI), Neustadt-Mariensee, Germany.
authors: Kristina
authors: K
authors: Kadlec
authors: Landesuntersuchungsamt Rheinland-Pfalz, Koblenz, Germany.
authors: Melanie
authors: M
authors: Hassel
authors: Institute of Farm Animal Genetics, Friedrich-Loeffler-Institut (FLI), Neustadt-Mariensee, Germany.
authors: Stefan
authors: S
authors: Schwarz
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015373:Bacterial Typing Techniques / Q000662:veterinary; D002417:Cattle; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D005260:Female; D005858:Germany / Q000453:epidemiology; D032023:Integrons / Q000235:genetics; D008414:Mastitis, Bovine / Q000453:epidemiology / Q000382:microbiology*; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D058885:Multilocus Sequence Typing / Q000662:veterinary; D010802:Phylogeny; D010957:Plasmids / Q000235:genetics*; D012093:Replicon / Q000235:genetics; D001618:beta-Lactamases / Q000235:genetics*; D047090:beta-Lactams / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D047090:beta-Lactams; D001618:beta-Lactamases
keywords: Class 1 integron; Co-resistance; IncI1; MLST; Milk; Resistance genes