Comparison of competitive exclusion with classical cleaning and disinfection on bacterial load in pig nursery units

Background: Colonisation of the environment of nursery units by pathogenic micro-organisms is an important factor in the persistence and spread of endemic diseases in pigs and zoonotic pathogens. These pathogens are generally controlled by the use of antibiotics and disinfectants. Since an increasing resistance against these measures has been reported in recent years, methods such as competitive exclusion (CE) are promoted as promising alternatives. Results: This study showed that the infection pressure in CE units after microbial cleaning was not reduced to the same degree as in control units. Despite sufficient administration of probiotic-type spores, the analysed bacteria did not decrease in number after 3 production rounds in CE units, indicating no competitive exclusion. In addition, no differences in feed conversion were found between piglets raised in CE and control units in our study. Also, no differences in faecal consistency (indicator for enteric diseases) was noticed. Conclusion: These results indicate that the CE protocol is not a valuable alternative for classical C&D

Prevalence and genetic diversity of livestock-associated methicillin-resistant Staphylococcus aureus on Belgian pork

Since the first description of livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA), a high prevalence was observed in pigs. At present, questions remain about the transmission of LA-MRSA to the general human population through pork. The objectives of the present study were to determine the prevalence of LA-MRSA in Belgian pork and to determine the role of the pork production chain and butcheries in transmission of LA-MRSA to the human population. Pig meat samples (chops, bacon, minced pork, ribs, forelimbs, and ears; n=137) originating from four butcheries (A through D) were spread plated on ChromID MRSA plates both before and after overnight enrichment culture. Suspect colonies were confirmed using a MRSA-specific triplex PCR assay and a CC398-specific PCR assay. The isolates (n = 147) were further characterized by SCCmec typing, multiple-locus variable number tandem repeat analysis, and antimicrobial susceptibility testing, a selection of isolates were subjected to pulsed-field gel electrophoresis and spa typing. Direct plating revealed a MRSA prevalence of 8%. After enrichment, MRSA was isolated from 98 (72%) of 137 samples of which the majority were from rib, ear, and forelimb. The majority (97%) of obtained isolates belonged to CC398, the main LA-MRSA type. A high level of genetic diversity was noted among the isolates from one butchery. Thirty antimicrobial susceptibility profiles were found; 13 and 9% of the isolates had Cip-Tet-Tri and Gen-Kan-Tet-Tob-Tri profiles, respectively. These results indicate the importance of enrichment for MRSA detection of pork. The observed genetic diversity of the isolates indicated that the pork production chain can be considered a source of multiple MRSA types that could be transmitted to the human population through cross-contaminated meat

Identification and biocide susceptibility of dominant bacteria after cleaning and disinfection of broiler houses

Hygiene in animal production is key for both farm management and food safety. Cleaning and disinfection (C&D) of broiler houses is essential to manage farm hygiene. Still high levels of total aerobic flora after C&D in broiler houses are reported. However, little is known about the microbial composition after cleaning (AC) and after disinfection (AD). In addition, the question why some bacterial species/isolates are still present AD whereas others are killed remains. The study was carried out in 4 broiler houses. Sampling was performed AC and AD. The disinfectant was based on hydrogen peroxide and peracetic acid. Enumerations were carried out for total aerobic flora, Enterococcus spp. and Enterobacteriaceae. The dominant bacteria present was assessed by (GTG) 5 analysis and 16S rRNA gene sequence analysis. Moreover, minimum bactericidal concentration (MBC) tests were carried out on 18 selected isolates belonging to the Enterobacteriaceae family and 10 Enterococcus faecium isolates. A wide variety of bacteria were detected AC and AD. In total, 363 and 255 isolates were identified AC and AD, respectively, resulting in a total of 109 identified species. The most dominant bacteria belonged to Brevibacterium, Brachybacterium, and Staphylococcus AC and Bacillus, Brevibacterium, and Staphylococcus AD. At both sampling moments, Enterococcus faecium was dominant among the Enterococcus spp. isolates. On the selective medium for Enterobacteriaceae, the genera Enterobacter and Pantoea and Aeromonas (non Enterobacteriaceae) were dominant AC while Escherichia, Lelliottia, and Pantoea were dominant AD. In addition, species pathogenic to poultry and humans were identified not only AC but also AD. MBC results showed no trend in selection of less susceptible isolates for the used disinfectant AD compared to AC. Finally, the recommended concentration of the disinfectant (i.e., 0.5% commercial solution of hydrogen peroxide and peracetic acid) seemed too low to kill Enterobacteriaceae