Fachbereich Veterinärmedizin



    Detection of plasmid-borne extended-spectrum β-lactamase (ESBL) genes in Escherichia coli isolates from bovine mastitis (2017)

    Zeitschriftenartikel / wissenschaftlicher Beitrag
    Freitag, Christin
    Michael, Geovana Brenner (WE 7)
    Kadlec, Kristina
    Hassel, Melanie
    Schwarz, Stefan (WE 7)
    Veterinary Microbiology; 200 — S. 151–156
    ISSN: 0378-1135
    DOI: 10.1016/j.vetmic.2016.08.010
    Pubmed: 27566885
    Institut für Mikrobiologie und Tierseuchen

    Robert-von-Ostertag-Str. 7-13
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    14163 Berlin
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    Abstract / Zusammenfassung

    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-14 and 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.