VapB type 8 plasmids in Rhodococcus equi isolated from the small intestine of pigs and comparison of selective culture media

Abstract

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.

Novel bovine-associated pVAPN plasmid type in Rhodococcus equi identified from lymph nodes of slaughtered cattle and lungs of people living with HIV/AIDS

“…Rhodococcus equi isolates recovered from human cases have shown high frequency of porcine‐associated type, in spite of a lack of history of contact between human patients with rhodococcosis and domestic pigs or their environment being reported, suggesting that pig‐to‐human infection might occur by ingestion of undercooked pig meat contaminated with pVAPB type from lymph nodes and/or faeces (Lara et al., ; Ribeiro, Takai et al., ; Takai et al., ). In this scenario, based on the recent description of a novel bovine‐associated pVAPN type, the same hypothesis might be valid in beef, especially in countries where undercooked meat is a habit of human consumption.…”

“…In addition, a total of 100 convenience sample of small intestinal content (faeces) were collected from 100 different cattle without enteric signs. All faecal samples were aseptically aspired according to previously described (Lara et al., ). The cattle were of various age and breeds.…”

“…All specimens from cattle (lymph nodes and faeces) and of human origin (bronchial wash, blood, abscesses, skin and fragments of organs) were subjected to microbiological culture on sheep blood agar (5%) and MacConkey agar, aerobically incubated for 3 days at 37°C. In addition, cattle lymph node and faeces samples were cultured in CAZ‐NB (ceftazidime, novobiocin and cycloheximide) selective media (Lara et al., ). Rhodococcus equi compatible colonies and other microorganisms were classified using conventional phenotyping methods (Prescott, ; Quinn et al., ).…”

“…Rhodococcus equi strains are major cause of a life-threatening pyogranulomatous bronchopneumonia in foals up to 6 months, whereas in non-equine domestic species and wildlife, the pathogen sporadically or rarely develops clinical signs (Meijer & Prescott, 2004;Prescott, 1991), except pigs and wild boars where is a major causal agent of purulent lymphadenitis, not previously suspected of Mycobacterium species (Komijn et al, 2007;Lara et al, 2015;Makrai et al, 2002;Sakai et al, 2012).…”

“…In turn, sources of infection and routes of transmission of the pathogen to humans remain poorly understood, although inhalation, and history of contact with livestock and environment of farms are considered to be risk factors (Meijer & Prescott, 2004;Prescott, 1991;V azquez-Boland et al, 2013). Recently, foodborne transmission is seemed as probable route, particularly in countries where undercooked or raw livestock meat are traditionally consumed (Lara et al, 2015;Ribeiro, Takai et al, 2011).…”