Bacterial contamination of table eggs and the influence of housing systems

With the introduction of alternative housing systems for laying hens in the EU, recent research has focussed on the bacterial contamination of table eggs, e.g. eggshell and egg content contamination. Contamination of eggshells with aerobic bacteria is generally higher for nest eggs from non-cage systems compared to nest eggs from furnished cages or eggs from conventional cages. Studies indicate limited or no systematic differences in eggshell contamination with aerobic bacteria between eggs laid in the nest boxes of furnished cages and eggs laid in conventional cages. The major differences found in experimental studies between cage- and non-cage systems are less pronounced under commercial conditions. The effect of housing system on eggshell contamination with specific groups of bacteria is variable. Limited information is available on the influence of housing system on egg content contamination. Recent research does not indicate large differences in egg content contamination between eggs from cage- and non-cage systems (ignoring outside nest and floor eggs). The microflora of the eggshell is dominated by Gram-positive bacteria, whereas Gram-negative bacteria are best equipped to overcome the antimicrobial defences of the egg content. Much of the research on eggshell and egg content contamination focuses on Salmonella, since infection with Salmonella enteritidis, resulting from the consumption of contaminated eggs or egg products, is still a major health problem. Observed Salmonella prevalence on the eggshell and in the egg content vary, depending on the fact whether investigations were based on randomly sampled table eggs or on eggs from naturally infected hens. The limited information available on other pathogens shows that they are exclusively isolated from the eggshell and not from the internal contents

Effect of a pre-milking teat foam and a liner disinfectant on the presence of mesophilic and (proteolytic) psychrotrophic bacteria prior to milking

Contamination of raw milk by psychrotrophs can lead to the production of heat-resistant proteases and subsequent spoilage of UHT milk. Therefore, this research communication evaluated the effect of a pre-milking teat disinfectant (active components: L-(+)-lactic acid and salicylic acid) and a liner disinfectant (active components: peracetic acid and hydrogen peroxide) on the number of mesophilic and (proteolytic) psychrotrophic bacteria prior to milking. The teat orifices of 10 cows were sampled using a swabbing procedure before and after treatment with a pre-milking teat disinfectant on six subsequent days. On the teat orifices, there was a small but statistically significant decrease in the psychrotrophic bacterial counts between pre and post dipping. No differences were observed for the mesophilic bacterial counts and proteolytic active counts. Liners were also sampled using swabs pre and post disinfection. No statistically significant decrease in the bacterial counts was observed post liner disinfection, although there was a numerical decrease. Sixty-two percent of the proteolytic psychrotrophs were pseudomonads: 16.5% of which were P. fragi, 14.3% P. lundensis, 10.0% P. fluorescens and 2.9% P. putida. Trinitrobenzenesulfonic acid (TNBS) analysis revealed a wide variety in proteolytic activity (from 0 to 55 mu mol glycine/ml milk) and the presence of high producers. It can be concluded that there was only a minor effect of teat and liner disinfection on the psychrotrophic bacterial counts indicating that the measures presented did not result in a reduction of the targeted bacteria on teat orifices and liners

A 10-day vacancy period after cleaning and disinfection has no effect on the bacterial load in pig nursery units

Background: Biosecurity measures such as cleaning, disinfection and a vacancy period between production cycles on pig farms are essential to prevent disease outbreaks. No studies have tested the effect of a longer vacancy period on bacterial load in nursery units. Methods: The present study evaluated the effect of a 10-day vacancy period in pig nursery units on total aerobic flora, Enterococcus spp., Escherichia coli, faecal coliforms and methicillin resistant Staphylococcus aureus (MRSA). Three vacancy periods of 10 days were monitored, each time applied in 3 units. The microbiological load was measured before disinfection and at 1, 4, 7 and 10 days after disinfection. Results: No significant decrease or increase in E. coli, faecal coliforms, MRSA and Enterococcus spp. was noticed. Total aerobic flora counts were the lowest on day 4 after disinfection (i.e. 4.07 log CFU/625 cm(2)) (P < 0.05), but the difference with other sampling moments was limited (i.e. 0.6 log CFU/625 cm(2)) and therefore negligible. Furthermore, this observation on day 4 was not confirmed for the other microbiological parameters. After disinfection, drinking nipples were still mostly contaminated with total aerobic flora (i.e. 5.32 log CFU/625 cm(2)) and Enterococcus spp. (i.e. 95 % of the samples were positive) (P < 0.01); the feeding troughs were the cleanest location (total aerobic flora: 3.53 log CFU/625 cm(2) and Enterococcus spp.: 50 % positive samples) (P < 0.01). Conclusions: This study indicates that prolonging the vacancy period in nursery units to 10 days after disinfection with no extra biosecurity measures has no impact on the environmental load of total aerobic flora, E. coli, faecal coliforms, MRSA and Enterococcus spp.

Inhibition of Salmonella Typhimurium by medium chain fatty acids in an in vitro simulation of the porcine caecum

To lower the contamination of pork meat with Salmonella, feed additives such as medium chain fatty acids (MCFA\u27s) can be applied at the primary production level. An in vitro continuous culture system, simulating the porcine caecum, was developed for investigating the effect of MCFAs on the pig intestinal microbial community. The system was monitored by plating on selective media, 16S rDNA PCR denaturing gradient gel electrophoresis (PCR-DGGE) and HPLC analysis of fermentation products. In a simulation of the porcine caecum without MCFA treatment, with Salmonella Typhimurium added after stabilization of the microbial community, the strain could establish itself at a stable population size of about 5 log cfu/ml. The effect of selected MCFAs was observed from all monitored parameters and depended on chain length and concentration applied. At a dose of 15 mM, caproate and caprinate did not show any pronounced effect, while a clear Salmonella inhibiting effect (3 log units reduction) was found for caprylate. Doubling the caprylate dose did not result in enhanced Salmonella inhibition

P12-11. Resistance to the CD4 mimetic mini protein M48-U1 induces changes in a highly conserved region on the HIV-1 gp120 envelope protein

International audienc

Transmissão materno-fetal de diferentes subtipos de HIV-1 entre gestantes infectadas na Nigéria

The rate of mother-to-child transmission (MTCT) of HIV as well as the implications of the circulating multiple subtypes to MTCT in Nigeria are not known. This study was therefore undertaken to determine the differential rates of MTCT of HIV-1 subtypes detected among infected pregnant women before ARV intervention therapy became available in Nigeria. Twenty of the HIV-positive women who signed the informed consent form during pregnancy brought their babies for follow-up testing at age 18-24 months. Plasma samples from both mother and baby were tested for HIV antibody at the Department of Virology, UCH, Ibadan, Nigeria. All positive samples (plasma and peripheral blood mononuclear cells - PBMCs) were shipped to the Institute of Tropical Medicine, Antwerp, Belgium, where the subtype of the infecting virus was determined using the HMA technique. Overall, a mother-to-child HIV transmission rate of 45% was found in this cohort. Specifically, 36.4%, 66.7% and 100% of the women infected with HIV-1 CRF02 (IbNg), G and B, respectively, transmitted the virus to their babies. As far as it can be ascertained, this is the first report on the rate of MTCT of HIV in Nigeria. The findings reported in this paper will form a useful reference for assessment of currently available therapeutic intervention of MTCT in the country.A taxa de transmissão materno-fetal (MTCT) do HIV bem como as implicações dos múltiplos subtipos circulantes para MTCT na Nigéria não são conhecidos. Este estudo foi realizado para determinar as diferentes taxas de MTCT dos subtipos de HIV-1 detectados entre gestantes infectadas antes que a administração da terapia ARV estivesse disponível na Nigéria. Vinte das mulheres HIV positivas que assinaram o consentimento durante a gravidez trouxeram seus filhos para seguimento na idade de 18-24 meses. Amostras de plasma de ambos, mãe e filho foram testadas para anticorpos HIV no Departamento de Virologia, UCH, Ibadan, Nigéria. Todas as amostras positivas (plasma e células mononucleares do sangue periférico - PBMCs) foram enviadas para o Instituto de Medicina Tropical da Antuérpia, Bélgica, onde os subtipos de vírus infectantes foram determinados utilizando-se a técnica HMA. No conjunto, uma taxa de transmissão de HIV, materno-fetal, de 45% foi encontrada neste grupo. Especificamente, 36,4%, 66,7% e 100% das mulheres infectadas com HIV-1 CRF02 (IbNg), G e B, respectivamente, transmitiram o vírus para seus filhos. Até onde pode ser verificado, este é o primeiro relato da taxa de MTCT do HIV na Nigéria. Os achados relatados neste trabalho serão uma útil referência para estimar a qualidade das terapêuticas atuais disponíveis para MTCT neste país

Expression study by real-time quantitative RT-PCR of the Salmonella typhimurium mntH gene

The aim of our study was to compare the mntH expression of different Salmonella Typhimurium strains and other Salmonella serovars with real-time RT-PCR. Following the mntH expression in function of the growth showed that the mntH expression of S. Typhimurium is growth dependent. A strong decrease of the mntH expression is noticed when the growth reaches 1.78 108 CFU/ml. After induction with EDTA or H2O2, variations between different S. Typhimurium strains were observed. For some S. Typhimurium strains a 10 to 20 times higher mntH expression was noticed after H2O2 induction. The EDTA induction was for most strains lower (5 to 10 times) but also variations between different strains were observed. The other Salmonella serovars were strongly induced after H2O2 but not after EDTA induction

Is competitive exclusion a valuable alternative for classical cleaning and disinfection of pig-growing units?

Colonization of the environment of pig-growing units by pathogenic microrganisms is an important factor in development of endemic diseases in pigs and, in spreading of zoonotic diseases. These pathogens are mostly controlled by the use of antibiotics and disinfection during vacancy. Because, the past years an increasing resistance against these measures is noticed, alternative methods such as competitive exclusion (CE) are promoted as promising. In this study the effect of a CE protocol on the bacterial infection in piggrowing units was compared to a classical cleaning and disinfection (C&D) protocol. Tests were performed during three successive production rounds using multiple identical pig-growing units. CE protocol consisted of cleaning (no disinfection) after loading piglets and spraying probiotic bacteria (Bacillus spp. spores) during vacancy and production. The cleaning product also contained Bacillus spores. Sampling was performed at different time-points: immediately after pig loading (manure still present); 24 hours after cleaning (CE units) or after disinfection (control units); after one week and five weeks of production (piglets present). At each time point, swab samples for analyses were taken. Enumerations of bacterial spores, Enterococcus spp., E. coli, fecal coliforms and MRSA and detections of E. coli, fecal coliforms and MRSA were performed. Next to bacterial analyses, also feed conversion and fecal consistency was monitored. This study showed that, although probiotic spores were administered well, the analyzed bacteria were not decreased after three production rounds in CE units and remained on the same level as the control units (C&D). Also, the infection pressure in CE units during vacancy was not as much reduced as after the disinfection-step in control units. Finally, no differences in feed conversion and fecal consistency were found. These results indicate that the used CE protocol is not a valuable alternative for classical C&D