Biomedical subjects

L J A Lipman

Publications and source records attributed to L J A Lipman.

11 recordsLinked to original sources

PubMed2006

[Swimming in summer].

It happens every summer: 'Swimming prohibited because of cyanobacteria'. Blooming of these toxine producing bacteria in warm summer months is a well known risk for swimming human beings. But how big is this risk for swimming dogs? And how big are other risks? In this article these risks are assessed for dogs that occasionally swim in surface water during the summer in the Netherlands. Based on these findings an advice will be given for dog owners to keep these risks for waterborne infections as small as possible.

Animals↗

PubMed2006

Antimicrobial properties of salt (NaCl) used for the preservation of natural casings.

The antimicrobial properties of salt (NaCl) used for the preservation of natural casings were studied by investigating the survival of six bacterial species in natural casings at different water activity (aw) levels. Individual sheep casings were inoculated with ca. 10(5) colony-forming units (cfu) g(-1) of Escherichia coli, Salmonella typhimurium, Listeria monocytogenes, Staphylococcus aureus, Clostridium perfringens and 10(2)cfu g(-1) of E. coli O157:H7. The casings were stored at 20+/-1.5 degrees C in different brines and dry salt, giving aw-levels of 0.90 aw, 0.87aw, 0.85 aw, 0.83 aw and 0.75 aw. Samples were taken at day 1, 3, 6, 8, 13, 20, 27 and 30 after inoculation and the number of bacteria present was determined. Based on survival curves, death rates (day(-1)) were calculated to quantify the reduction in log10 cfu g(-1) per day. The influence of aw on death rates was higher for Gram-negative bacteria than for Gram-positive bacteria. The death rates were overall higher for Gram-negatives than for Gram-positives. No clear reduction in the survival of C. perfringens in relation to any aw level was observed in this study. These results indicate that the antimicrobial properties of salt used for the preservation of natural casings are sufficient to reduce the bacterial contamination (except for Clostridium spores) well below acceptable levels at a water activity level of 0.85 or lower during a 30-day storage period.

Animals↗

PubMed2005

Potential routes of acquisition of Arcobacter species by piglets.

The aim of this study was to determine the prevalence and the transmission routes of Arcobacter spp. in sows and their offspring on a breeding farm. Twelve Arcobacter-positive sows and their litters were studied for this purpose. Analysis of rectal samples showed a high prevalence of Arcobacter spp. among the sows (approximately 42% of the sows carried one or more Arcobacter species). Intermittent excretion of one particular species and shifts in excretion from one species to another were observed in individual animals over time. The detection of Arcobacter spp. in amniotic fluid of the sows and in rectal samples from newborn piglets (ranging from 38.5-83.3% per litter), as well as the high similarity between PFGE profiles of Arcobacter isolates from sows and their respective newborns indicated the existence of an intra-uterine transmission route for Arcobacter spp. Specific antibodies against Arcobacter spp. were detected in colostrum by Western blot. At 2 weeks of age, only a few piglets were positive for Arcobacter. The reappearance of Arcobacter in these piglets at Week 3 and the shift in the Arcobacter species detected (from a prominent presence of A. cryaerophilus at birth to the presence of A. skirrowii and A. butzleri at 3 weeks after birth) showed that a post-natal infection route from their mothers, newcomers or the environment to the piglets existed. Thus, in this manuscript the transmission of Arcobacter spp. (both vertical and horizontal) from carrying sows to their offspring is demonstrated.

Amniotic Fluid↗

PubMed2004

Antagonistic activities of several bacteria on in vitro growth of 10 strains of Campylobacter jejuni/coli.

Chicken meat contaminated with Campylobacter jejuni can be the source of human enteritis. To decrease the risk of human infection, Campylobacter should be controlled at farm levels. Orally given probiotic bacteria could prevent colonisation of chicken with pathogenic bacteria like Campylobacter. The aim of this study was to investigate the effect of different bacteria on Campylobacter growth. Our results demonstrated that bacteria isolated from conventional chicken had potential inhibitory activities against Campylobacter. Other bacteria not isolated from chickens but with known antagonistic capacities, e.g. Enterococcus (56 strains) and Escherichia coli (20 strains), did not show any negative effect on Campylobacter. Interestingly, one Lactobacillus (P93) strain isolated from the chicken gut showed bactericidal activity against all tested Campylobacter. The bactericidal effect was characterised as the production of organic acids in combination with probably production of an anti-Campylobacter protein. In a co-culture study of Campylobacter and Lactobacillus (P93), the culturability of Campylobacter was under the detection limit after 48 h of incubation. A chicken experiment is needed to further evaluate the effect of the promising probiotic bacteria against Campylobacter colonisation in chicken.

Animals↗

PubMed2004

Effect of organic acids in drinking water for young broilers on Campylobacter infection, volatile fatty acid production, gut microflora and histological cell changes.

Water is a prominent vehicle for Campylobacter spread throughout a chicken flock. The aim of this study was to evaluate the effect of organic acids administered through the drinking water, as a decontamination method, on gut microflora and the development of lesions in the gastrointestinal tracts of young broilers inoculated with 2 different doses of Campylobacter. The results revealed that most of the chickens were infected with Campylobacter at the end of the experiment. The drinking water was free of Campylobacter throughout the study. No difference of volatile fatty acid levels between treatment and control groups was observed in the crop and cecal contents. In the cecal contents, the total aerobic bacteria numbers were significantly higher in the treatment groups compared with the control groups (P < 0.01 and P < 0.04, respectively). Moreover, no damaged epithelial cells were observed in the chicken gut due to consumption of acidified drinking water. Acidified drinking water could therefore play a crucial role in a biosecurity strategy of preventing Campylobacter spread via drinking water in broiler flocks.

Animals↗

PubMed2003

Survival and resuscitation of ten strains of Campylobacter jejuni and Campylobacter coli under acid conditions.

The culturability of 10 strains of Campylobacter jejuni and Campylobacter coli was studied after the bacteria were exposed to acid conditions for various periods of time. Campylobacter cells could not survive 2 h under acid conditions (formic acid at pH 4). The 10 Campylobacter strains could not be recovered, even when enrichment media were used. Viable cells, however, could be detected by a double-staining (5-cyano-2,3-ditolyl tetrazolium chloride [CTC]-4',6'-diamidino-2-phenylindole [DAPI]) technique, demonstrating that the treated bacteria changed into a viable but nonculturable (VBNC) form; the number of VBNC forms decreased over time. Moreover, some VBNC forms of Campylobacter could be successfully resuscitated in specific-free-pathogen fertilized eggs via two routes, amniotic and yolk sac injecting.

Animals↗

PubMed2002

[Bioterrorism: the role of veterinarians in detection and prevention].

The fear of terrorist attacks has increased since the events of 11 September 2001 in New York. In the weeks following the terrorist attack, letters containing anthrax spores were received at various locations in the USA. This shows that bioterrorism is possible and that is necessary to be prepared for the potential release of biological agents. Such agents can be distributed not only via the air and drinking water but also via household pets. The aim of terrorist attacks, namely, the disruption of society and daily life, can be achieved in three ways, ways which are of importance to practising veterinarians, namely, via pets, via contamination of pet foods of animal origin, and by the spread of infectious animal diseases that have far-reaching economic consequences. These ways are discussed in this article, together with possible ways in which veterinarians can act to diminish the consequences of such an event.

Animal Diseases↗

PubMed2002

Spatial and temporal variation of the intestinal bacterial community in commercially raised broiler chickens during growth.

The objective of this study was to determine whether host, compartment, or environmental specific factors play an important role in the establishment of the intestinal microflora in broiler chickens during growth. This objective was addressed using a 16S rDNA approach. PCR-amplicons from the V6 to V8 regions of the 16S rDNA of intestinal samples were separated by denaturing gradient gel electrophoresis (DGGE). The number of bands in all intestinal compartments increased when broilers grew older, indicating that the dominant bacterial community becomes more complex when chickens age. Each chicken had a unique banding pattern for all locations in the intestinal tract, irrespective of the age of chickens. This suggests that host-related factors affect the establishment of the dominant bacterial community. Banding patterns of intestinal compartments within one chicken were different from each other for broilers older than 4 days, except for both ceca which were highly similar. In 4-day-old broilers, banding patterns from crop, duodenum, and ileum were very similar. We conclude that (unknown) host specific factors play an important role in the development of the intestinal bacterial community in each broiler chicken. Furthermore, compartment-specific factors play an important role in the bacterial development of each intestinal compartment within one chicken.

Animals↗

PubMed2002

[From veterinarian to quality control manager. What is going to change in the Netherlands for the practicing large animal veterinarian under influence of the White Paper about food safety?].

The work of farm animal practitioners will change in the coming years as a result of the White Paper on food safety. Both government and the Royal Veterinary Association of the Netherlands are working on an accreditation system for veterinarians. The veterinary practitioner is a link in the chain to achieve safe products. Where in the past emphasis was on the individual animal, it will now be on the herd or flock. The veterinarian will officially determine the health status of the farm, which in turn will play a role in the inspection procedures at the slaughterhouse. This form of farm management will become compulsory for all stockholders within the framework of the Veterinary Network for Supervision. In turn, these developments will affect the veterinary medicine curriculum. New subjects such as quality management will become increasingly important.

Animal Welfare↗

PubMed2002

Comparison of the sensitivity of manual and automated immunomagnetic separation methods for detection of Shiga toxin-producing Escherichia coli O157:H7 in milk.

AIM: To determine the sensitivity of methods for detection of injured and uninjured Escherichia coli O157:H7 (E. coli O157) in raw and pasteurized milk. METHODS AND RESULTS: Raw milk, pasteurized milk with 1.5% fat content and pasteurized milk with 3.5% fat content were spiked with E. coli O157 at low levels. The samples were enriched in modified tryptone soya broth with novobiocin (mTSBn) at 37 degrees C. Aliquots of the enriched culture were analysed either by manual immunomagnetic separation (MIMS) and culturing on sorbitol MacConkey agar with or without cefixime and potassium tellurite (SMACct or SMAC), or by automated immunomagnetic separation and integrated ELISA (EiaFosstrade mark). Uninjured E. coli O157 organisms were detected in milk by both methods at 1 cfu 10 ml-1 sample). Injured organisms were detected at levels of about 4 cfu 10 ml-1 sample. Direct enrichment in mTSBn (22 h incubation) showed better sensitivity for injured cells than enrichment in buffered peptone water (BPW, 22 h incubation), or in a two-step enrichment consisting of BPW (6 h, 37 degrees C) and mTSBn (16 h, 37 degrees C), successively. CONCLUSIONS: The methods showed equal sensitivity in that they were both able to detect 1 cfu 10 ml-1 milk sample. Injured organisms can be detected and isolated at a level almost as low as this. A resuscitation step is not recommended for the detection and isolation of injured and non-injured E. coli O157 from milk. SIGNIFICANCE AND IMPACT OF THE STUDY: Due to the dilution of contamination in the bulk tank, analysis of milk for the presence of E. coli O157 requires a very sensitive method. Both methods described here are useful for such analysis.

Animals↗

PubMed2002

In vitro study on the effect of organic acids on Campylobacter jejuni/coli populations in mixtures of water and feed.

Gastroenteritis caused by Campylobacter spp. infection has been recognized as one of the important public health problems in the developed countries. Outbreaks mostly originate from the consumption of contaminated poultry or infected water. The aim of this study was to determine the bactericidal activity on Campylobacter spp. of organic acids individually and in combinations at different pH levels and times and to compare bactericidal activities with activities of commercially available products. Ten strains of Campylobacter spp. were added in a mixture of water with commercial broiler feed, separately adjusted by four acids: formic, acetic, propionic, and hydrochloric acids, into pH 4.0, 4.5, 5.0, and 5.5. A combination of three organic acids was used in two different formulation ratios: formic:acetic:propionic at 1:2:3 and 1:2:5, at pH 4.0, 4.5, 5.0, and 5.5. All organic acids showed the strongest bactericidal effect on Campylobacter at pH 4.0. In contrast, at pH 5.0 and 5.5, the bactericidal activity of the four acids was low. The combination of organic acids showed a synergistic bactericidal activity at pH 4.5. Interestingly, the effect of the combined organic acids was stronger than the commercial products. Morphological cell changes were studied by transmission electron microscopy to determine the effect of the organic acids on the cell structure of Campylobacter. Some loss of outer membranes of the bacteria could be found in treated groups. Therefore, it can be concluded that organic acids, individually or in combination, have a strong bactericidal effect on Campylobacter spp. Routine application of organic acids to the water supply on poultry farms could prevent or diminish Campylobacter transmission.

Acetic Acid↗