Abstract
Enterobacteriaceae are the main etiological agents of environmental bovine mastitis and are often resistant to antimicrobials, especially β-lactam class due to the production of β-lactamases. These can be classified into several groups according to the molecular structure and substrate activity. The present study evaluated the profile of pheno-genotypic resistance to β-lactams, with emphasis on the functional detection of β-lactamases. The isolates were obtained from milk samples from farms located in the interior region of the state of Rio de Janeiro. 47.6% (20/42) of the bacterial isolates producing enzymes classified as Group 1 (AmpC type) were detected, and in disk approximation test, 30% were classified as the inducible type and 70% as not inducible. To the best of the authors’ knowledge, this is the first report on AmpC β-lactamase production in enterobacteria involved in mastitis etiology in Brazil. Key words: Raw milk, environmental mastitis, dairy cattle, antimicrobial resistance.
Highlights
AmpC β-la actama ase prroductiion in entero obacteria assoc ciated with w bo ovine mastittis in B
Bacteria producing β-lactamases already widely studied in clinical microbiology can be retrieved from cow's milk, beef, pork and chicken, along with animal faeces (Li et al, 2007; Locatelli et al, 2009; Bush and Jacoby, 2010; Geser et al, 2012; Silva and Lincopan, 2012; Dahmen et al, 2013). β-Lactamasesproducing Enterobacteriaceae in raw milk can pose a risk to public health in countries even developed ones, where raw cheese is commonly consumed (Dahmen et al, 2013)
The present study evaluated production of AmpC β-lactamases in enterobacteria isolated from dairy herds in the interior region of the state of Rio de Janeiro, Brazil
Summary
AmpC β-la actama ase prroductiion in entero obacteria assoc ciated with w bo ovine mastittis in B. % (20/42) of the bacteria al isolates p producing enzymes cllassified as Group 1 (Am mpC type) were w detected d, and in dis sk approxim mation test, 3 These enzymes can be detected by phenotypic antimicrobial markers and confirmed by specific tests. Bla gene encode enzyme production and its expression can be induced by the presence of β-lactam or can be continuously activated (Livermore, 1995).
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