RESUMEN
Mycoplasmas are known as the minimalist microorganisms in the microbes' world. Their minimalist nature makes them highly sensitive to the environmental conditions and limits their ability to survive for extended periods outside their animal host. Nevertheless, there are documented instances of mycoplasma transmission over significant distances and this phenomenon may be linked to relatively unexplored abilities of mycoplasmas, such as their capacity to synthesize biofilm-the predominant mode of bacterial growth in nature. The authors decided to establish a method aimed at inducing the clustering of mycoplasma planktonic cells within a biofilm in vitro and subsequently assess the capacity of certain avian mycoplasmas to synthesize a biofilm. A total of 299 avian mycoplasma isolates were included in the study, encompassing both pathogenic (Mycoplasma gallisepticum, M. synoviae, M. meleagridis, M. iowae) and non-pathogenic species (M. gallinaceum, M. gallinarum, M. iners and M. pullorum). The authors successfully demonstrated the feasibility of inducing avian mycoplasmas to synthetize in vitro a biofilm, which can be visually quantified. The only species that did not produce any biofilm was M. iowae. In general, the pathogenic mycoplasmas produced greater quantities of biofilm compared to the non-pathogenic ones. Furthermore, it was observed that the ability to produce biofilm appeared to vary, both qualitatively and quantitatively, not only among different species but also among isolates of a single species. Future studies will be necessary to determine whether biofilm production plays a pivotal epidemiological role for the pathogenic avian mycoplasmas.
RESUMEN
Italian beef production is mainly based on a feedlot system where calves are housed with mixed aged cattle often in conditions favourable to bovine respiratory disease (BRD). In Veneto, an indoor system is also used for imported bulls around 300-350 kg. Mycoplasmas, in particular Mycoplasma bovis and Mycoplasma dispar, contribute to BRD in young calves, but their role in the disease in older cattle has not been investigated. In this study, ten heads of cattle were selected from each of the 24 groups kept in 13 different farms. Bulls were sampled by nasal swabbing at 0, 15, and 60 days after arrival for Mycoplasma isolation. Identification was carried out by 16S-rDNA PCR followed by denaturing gradient gel electrophoresis. M. bovis, M. dispar, and M. bovirhinis were identified, and prevalence was analysed by mixed-effects logistic regression models. This showed that most bulls arrived free of M. bovis, but within two weeks, approximately 40% became infected, decreasing to 13% by the last sampling. In contrast, the prevalence of M. dispar was not dependent on time or seasonality, while M. bovirhinis only showed a seasonality-dependent trend. The Italian fattening system creates an ideal environment for infection with M. bovis, probably originating from previously stabled animals.
RESUMEN
Presence of Mycobacterium avium subsp. paratuberculosis (MAP) in beef has been reported as a public health concern because asymptomatically infected cattle may contain MAP in tissues that are used for human consumption. Associations between MAP carcasses contamination and animal characteristics such as age, breed, production type, and carcass classification were assessed. Cheek muscles from 501 carcasses were sampled cross-sectionally at a Danish abattoir and tested for presence of viable MAP and MAP DNA by bacterial culture and IS900 realtime PCR, respectively. Cheek muscle tissues from carcasses of two dairy cows were positive by culture whereas 4% of the animals were estimated with ≥10 CFU/gram muscle based on realtime PCR. Age was found to be associated with carcass contamination with MAP. The observed viable MAP prevalence in beef carcasses was low. However, detection of MAP and MAP DNA in muscle tissues suggested that bacteremia occurred in slaughtered cattle.
