The consumption of raw milk is currently increasing due to several beneficial aspects, such as nutritional qualities, taste, and health benefits. However, some authors highlight the potential risk associated with raw milk consumption. In Italy, while the absence of some pathogen microorganisms is set by the regional regulation DGR 381/2007, for other microorganisms, such as Leptospira, no recommendations are provided. Leptospira is not ascribed among classical milk pathogens; however, it can potentially be present in raw milk. The aim of this study was to evaluate the survival in raw milk of six serovars of Leptospira after storage at different temperatures (4 °C ± 2 °C, 20 °C ± 2 °C, and 30 °C ± 2 °C) for different incubation times (20 min, 45 min, 1 h, and 1 h and 30 min), in order to determine the potential risk for consumers. Moreover, the immediate effect of bovine, goat, and donkey raw milk on tested Leptospira serovars was visually evaluated. After incubation, all samples were subcultured in EMJH and incubated aerobically at 30 °C for 3 months. All inoculated media were weekly examined by dark-field microscope in order to assess Leptospira survival. Extemporary observation of strains' behavior in milk allowed to detect an almost immediate motility loss, and no leptospires were detected by microscopic observations carried out weekly during the trial period. According to our results, it could be possible to exclude raw milk as a source of Leptospira infection for consumers.
- MeSH
- aerobióza MeSH
- bakteriologické techniky MeSH
- časové faktory MeSH
- Equidae MeSH
- kozy MeSH
- Leptospira fyziologie MeSH
- mikrobiální viabilita * MeSH
- mléko mikrobiologie MeSH
- skladování potravin MeSH
- skot MeSH
- teplota MeSH
- zvířata MeSH
- Check Tag
- skot MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Itálie MeSH
Leptospira spp. are spirochete bacteria comprising both pathogenic and free-living species. The saprophyte L. biflexa is a model bacterium for studying leptospiral biology due to relative ease of culturing and genetic manipulation. In this study, we constructed a library of 4,996 random transposon mutants in L. biflexa. We screened the library for increased susceptibility to the DNA intercalating agent, ethidium bromide (EtBr), in order to identify genetic determinants that reduce L. biflexa susceptibility to antimicrobial agents. By phenotypic screening, using subinhibitory EtBr concentrations, we identified 29 genes that, when disrupted via transposon insertion, led to increased sensitivity of the bacteria to EtBr. At the functional level, these genes could be categorized by function as follows: regulation and signaling (n=11), transport (n=6), membrane structure (n=5), stress response (n=2), DNA damage repair (n=1), and other processes (n=3), while 1 gene had no predicted function. Genes involved in transport (including efflux pumps) and regulation (two-component systems, anti-sigma factor antagonists, etc.) were overrepresented, demonstrating that these genes are major contributors to EtBr tolerance. This finding suggests that transport genes which would prevent EtBr to enter the cell cytoplasm are critical for EtBr resistance. We identified genes required for the growth of L. biflexa in the presence of sublethal EtBr concentration and characterized their potential as antibiotic resistance determinants. This study will help to delineate mechanisms of adaptation to toxic compounds, as well as potential mechanisms of antibiotic resistance development in pathogenic L. interrogans.
- MeSH
- antiinfekční látky farmakologie MeSH
- bakteriální léková rezistence genetika MeSH
- bakteriální proteiny genetika MeSH
- biologický transport MeSH
- ethidium farmakologie MeSH
- fenotyp MeSH
- genová knihovna MeSH
- inzerční mutageneze MeSH
- Leptospira genetika fyziologie MeSH
- membránové transportní proteiny genetika MeSH
- mikrobiální testy citlivosti MeSH
- operon genetika MeSH
- tolerance léku genetika MeSH
- transpozibilní elementy DNA genetika MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- MeSH
- Arvicolinae MeSH
- hlodavci mikrobiologie MeSH
- Leptospira fyziologie MeSH
- myši MeSH
- populační dynamika MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Geografické názvy
- Československo MeSH
