ABSTRACT
UNLABELLED: The virulence-plasmid profile of Rhodococcus equi strains isolated from Suidae and humans is similar. Recent evidence suggests that the consumption of pork products contaminated with faeces might be a potential source of R. equi infections in humans, mainly to patients with rhodococcosis without history of contact with pigs or pig farms. This study investigated the virulence-associated genes (vapA and vapB) and plasmid profiles of R. equi among the 150 samples of small intestinal content obtained from slaughtered pigs. In addition, all samples were subjected to microbiological culture in conventional sheep blood agar and CAZ-NB, TCP and TVP selective media. A total of 40 (26·7%) of the samples recovered R. equi, with two samples recovering isolates harbouring the VapB type 8 plasmid. Among the 150 pigs sampled herein, CAZ-NB was considered the best selective medium for the isolation of R. equi from faeces. Our results provide evidence that the contamination of slaughtered pig carcasses with pathogenic R. equi might occur through faeces, representing a public health concern. Furthermore, this study is the first description of R. equi strains carrying the VapB plasmid in the gut of pigs. SIGNIFICANCE AND IMPACT OF THE STUDY: Intermediately virulent (VapB) is a common plasmid-type harboured by R. equi isolated from pigs and humans with AIDS. Curiously, humans with rhodococcosis usually have no history of contact with pigs or pig farms. Virulence-plasmid profile of 40 R. equi isolated among 150 small intestine content samples from pigs revelled two carrying isolates with the VapB type-8 plasmids. Moreover, comparison of three selective culture media shows that CAZ-NB was the best. Our results provide evidence that contamination of slaughtered pig carcasses with pathogenic R. equi might occur through faeces, representing a public health concern. Furthermore, R. equi carrying VapB type-8 plasmids types are described for the first time in the gut of the pig.
Subject(s)
Actinomycetales Infections/microbiology , Bacterial Proteins/genetics , Culture Media , DNA-Binding Proteins/genetics , Food Microbiology , Membrane Glycoproteins/genetics , Red Meat/microbiology , Rhodococcus equi/isolation & purification , Abattoirs , Animals , Brazil , Feces/microbiology , Humans , Intestine, Small/microbiology , Plasmids/genetics , Plasmids/isolation & purification , Rhodococcus equi/genetics , Swine , Swine Diseases/microbiology , Virulence/genetics , Virulence Factors/geneticsABSTRACT
A series of biologically active peptides and related compounds (opioid peptides, neurotensin, and bradykinin) were used as substrates or competitive inhibitors to study the structural requirements for peptide interaction with endopeptidase 22.19. The kinetics of hydrolysis of these peptides indicated that, in contrast to other proteases, the substrate specificity of endopeptidase 22.19 is not determined by the amino acids flanking the sensitive bonds of the substrates. The competition between bioactive peptide analogues and the quenched fluorescence substrate of endopeptidase 22.19 indicated that their length and their flexibility may be the dominant factors to explain their binding specificities. These peculiar features of endopeptidase 22.19 may be of importance to understand the physiological processes of conversion and inactivation of biologically active peptides.