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Marc Heyndrickx

Publications and source records attributed to Marc Heyndrickx.

At least 19 recordsLinked to original sources
PubMed2006

Influence of eggshell condensation on eggshell penetration and whole egg contamination with Salmonella enterica serovar enteritidis.

Shells of agar-filled and whole eggs were inoculated with 10(3) to 10(4) CFU of Salmonella enterica serovar Enteritidis per eggshell. The agar-filled eggs were used to study bacterial eggshell penetration, and the whole egg results were used to characterize contamination of the egg contents. In each group, half of the eggs were stored for 21 days at 20 degrees C and 60% relative humidity (RH), and the other half was stored for 24 h at 6 degrees C and then for 20 days at 20 degrees C. The latter conditions resulted in condensation on the eggshell for 30 min from the moment the eggs were placed in the 20 degrees C chamber. Taking into account the ages at which hens were studied (39, 53, and 67 weeks), an average of 62% of the eggshells with condensate were penetrated compared with 43% for the control group; this difference was significant (P < 0.01). No significant difference in whole egg contamination was found; 18% of the control eggs were contaminated compared with 22% of the condensate eggs. Whole egg contamination was significantly higher for eggs from the hens at an older age (67 weeks). This difference probably was not due to a higher penetration potential because differences were not observed for the corresponding agar-filled eggs. Condensation on the eggshell seemed to encourage bacterial penetration of the eggshell but had a smaller impact on whole egg contamination.

Age Factors↗
PubMed2005

Real-time reverse transcription PCR for the quantification of the mntH expression of Salmonella enterica as a function of growth phase and phagosome-like conditions.

This article presents an experimental design for measuring the mRNA expression in Salmonella enterica of the mntH gene in phagosome-mimicking conditions. The expression of mntH was quantified by real-time reverse transcription PCR for different S. enterica strains of porcine origin under different biological growth conditions which mimicked the environment inside the phagosome. The expression of mntH and the different control genes (16S rRNA, rpoD and gmk) varied according to the growth phase. For mntH a maximum in the expression was detected in the early exponential phase. To obtain an accurate quantification and reliable comparison of the mntH expression in different S. enterica strains under various biological conditions, the ratio mntH mRNA level to the normalization factor was determined. The latter is the geometric mean of the RNA level of three housekeeping genes 16S rRNA, rpoD and gmk calculated by the geNorm program. MntH was basally expressed in all tested S. enterica strains and induced by hydrogen peroxide (H(2)O(2)) or ethylenediaminetetraacetic acid (EDTA) in Brain Heart Infusion. Under the nutrient limiting conditions of Sauton medium, the basal mntH expression was higher than in BHI, whereas H(2)O(2) induced the expression 40 times. A similar induction was obtained for Salmonella in porcine peripheral blood monocytes (PBM).

Animals↗
PubMed2005

Identification of Paenibacillus larvae to the subspecies level: an obstacle for AFB diagnosis.

This study was initially aimed at developing a PCR-test to differentiate between the pathogenic agent of American foulbrood (Paenibacillus larvae subsp. larvae) and powdery-scale disease (P. larvae subsp. pulvifaciens) of the honeybee. The test was based on the "insert of clone 9" (iC9), referring to a cloned 1.9 kB HaeIII fragment that occurs only in the P. larvae subsp. larvae reference strains and possibly correlates with American foulbrood virulence. It was shown that an iC9-based PCR-test discriminates between the BCCM/LMG reference strains of both subspecies. However, the screening of 179 Belgian field strains revealed five isolates that gave no iC9-based amplicon, thus rather resembling to P. larvae subsp. pulvifaciens. In addition, they all produced acid from mannitol, a characteristic previously assigned to the pulvifaciens subspecies. Because the reference strains gave conflicting data, this carbohydrate acidification was not conclusive. Therefore, the exact taxonomic position of the five retained strains was determined by a polyphasic approach using SDS-PAGE, AFLP, and ERIC-based PCR. Four iC9-negative field strains could be identified as P. larvae subsp. larvae; the taxonomic position of the fifth field strain remained ambiguous. The latter was provisionally classified as a subspecies pulvifaciens strain on the basis of SDS-PAGE. The present paper demonstrates the existence of field strains that do not fit well in the subdivision of the species P. larvae into two subspecies. Knowing that only one of both subspecies represents the pathogenic agent of AFB, this is a serious obstacle for the diagnosis of this honeybee disease.

Animals↗
PubMed2005

Molecular and phenotypical characterization of Clostridium perfringens isolates from poultry flocks with different disease status.

Due to the diminished use of growth-promoting antibiotics in the European Union, Clostridium perfringens induced necrotic enteritis and subclinical disease have become important threats to poultry health. A study was set up to genotypically and phenotypically characterise C. perfringens isolates from poultry flocks with different health status. Animals from healthy flocks were sampled by cloacal swabs, while intestinal and liver samples of animals suffering from necrotic enteritis were analysed. A total of 27 isolates was obtained from 23 broiler flocks without clinical problems and 36 isolates were obtained from 8 flocks with clinical problems. Using PFGE typing, high genetic diversity was detected between isolates from different flocks. Isolates derived from flocks where disease outbreaks occurred were clonal within each flock, but each flock harboured a different clone. All isolates were of toxin type A. Isolates from 5 out of 35 PFGE types carried the cpb2 gene, encoding the beta2 toxin, and isolates from 2 out of 35 PFGE types harboured the cpe gene, encoding the enterotoxin. In vitro alpha toxin production for all isolates was quantified by enzyme-linked immunosorbent assay. It was shown that in vitro alpha toxin production of C. perfringens isolates from diseased flocks was not higher than in vitro alpha toxin production from isolates derived from healthy flocks.

Animals↗
PubMed2005

Characterization of Salmonella isolates from captive lizards.

Reptile-associated salmonellosis in humans is an increasing public health issue. This study aimed at characterizing Salmonella isolates from captive lizards and to compare them to human isolates. Salmonella was isolated from 25 of 33 cloacal and 47 of 79 faecal samples from captive lizards (75.8 and 59.5%, respectively). The strains belonged to 44 serotypes of subspecies I (27 serotypes), II (9), IIIb (3) and IV (5). Two strains, one of serotype Enteritidis and one of serotype Amsterdam, were resistant to nitrofurantoin. Invasion assays in Caco-2 cells were performed with 40 saurian isolates of subspecies I, 15 isolates of subspecies II, 4 strains of subspecies IIIb, 6 subspecies IV isolates and 17 human isolates of corresponding serotypes of subspecies I. Saurian isolates belonging to subspecies I invaded the Caco-2 cells to a higher extent than those from the other subspecies. The human isolates invaded the Caco-2 cells to a lesser degree compared to their saurian counterparts. In the same strains, the presence of virulence genes agfA, shdA, spvR, pefA and sopE was determined using PCR. Whereas agfA was detected in all strains, pefA was only detected in one saurian and in the human serotype Enteritidis strains. The spvR gene was detected in the same serotype Enteritidis strains and in 33% of the subspecies IV strains. The shdA gene was present in all the human isolates and in 86% of subspecies I saurian isolates. SopE was found in 17% of the human isolates, in 24% of the saurian subspecies I strains and in all of the subspecies IV strains.

Animals↗
PubMed2005

Study of mural painting isolates, leading to the transfer of 'Bacillus maroccanus' and 'Bacillus carotarum' to Bacillus simplex, emended description of Bacillus simplex, re-examination of the strains previously attributed to 'Bacillus macroides' and description of Bacillus muralis sp. nov.

A group of 24 strains was isolated from deteriorated mural paintings situated in Spain (necropolis of Carmona) and Germany (church of Greene-Kreiensen). (GTG)5-PCR genomic fingerprinting was performed on these strains to assess their genomic variability and the strains were delineated into four groups. Representatives were studied by 16S rRNA gene sequencing and were found to be closely related to Bacillus simplex and the species 'Bacillus macroides' (strain NCIMB 8796) and 'Bacillus maroccanus' (names not validly published) according to a fasta search. The close similarity between B. simplex, 'B. macroides' NCIMB 8796, 'B. maroccanus' and the mural painting isolates was confirmed by additional (GTG)5-PCR, ARDRA, FAME and SDS-PAGE analyses. Furthermore, these techniques revealed that strains of 'Bacillus carotarum', another name that has not been validly published, also showed high similarity to this group of organisms. On the other hand, it was shown that the strains labelled 'B. macroides' in different collections do not all belong to the same species. Strain NCIMB 8796 can be allocated to B. simplex, while strain DSM 54 (=ATCC 12905) shares the highest 16S rRNA gene sequence similarity with Bacillus sphaericus and Bacillus fusiformis (both around 98.6 %). On the basis of further DNA-DNA hybridization data and the study of phenotypic characteristics, one group of five mural painting strains was attributed to a novel species in the genus Bacillus, for which the name Bacillus muralis sp. nov. is proposed. Finally, the remaining mural painting strains, one (LMG 18508=NCIMB 8796) of two strains belonging to 'B. macroides' and strains belonging to 'B. maroccanus' and 'B. carotarum' are allocated to the species B. simplex and an emended description of B. simplex is given.

Bacillus↗
PubMed2005

Bacillus ruris sp. nov., from dairy farms.

Four novel ellipsoidal spore-forming Bacillus isolates with swollen sporangia, isolated from raw milk and feed concentrate, showed a high level of similarity in SDS-PAGE, fatty acid methyl esters and routine phenotypic tests. However, 16S rRNA gene sequence comparisons showed that this taxon was different from other related Bacillus species, and only a low level of DNA relatedness was found with the closest phylogenetic and phenotypic relative, Bacillus galactosidilyticus. This taxon could be differentiated from B. galactosidilyticus on the basis of morphological differences, stronger acid reactions with a wide range of substrates after 48 h incubation, and qualitative and quantitative differences in fatty acid content. On the basis of these data, a novel species, Bacillus ruris sp. nov., is proposed, with LMG 22866T (=DSM 17057T) as the type strain.

Animal Feed↗
PubMed2005

Incidence and diversity of potentially highly heat-resistant spores isolated at dairy farms.

The presence of highly heat-resistant spores of Bacillus sporothermodurans in ultrahigh-temperature or sterilized consumer milk has emerged as an important item in the dairy industry. Their presence is considered undesirable since they hamper the achievement of commercial sterility requirements. By using a selective 30-min heat treatment at 100 degrees C, 17 Belgian dairy farms were screened to evaluate the presence, sources, and nature of potentially highly heat-resistant spores in raw milk. High numbers of these spores were detected in the filter cloth of the milking equipment and in green crop and fodder samples. About 700 strains were isolated after the selective heating, of which 635 could be screened by fatty acid methyl ester analysis. Representative strains were subjected to amplified ribosomal DNA restriction analysis, 16S rRNA gene sequencing, percent G+C content, and DNA-DNA reassociations for further identification. The strain collection showed a remarkable diversity, with representatives of seven aerobic spore-forming genera. Bacillus licheniformis and Bacillus pallidus were the most predominant species overall. Twenty-three percent of the 603 spore-forming isolates proved to belong to 18 separate novel species. These findings suggest that the selective heating revealed a pool of unknown organisms with a higher heat-resistant character. This study showed that high spore counts can occur at the dairy farm and that feed and milking equipment can act as reservoirs or entry points for potentially highly heat-resistant spores into raw milk. Lowering this spore load by good hygienic measures could probably further reduce the contamination level of raw milk, in this way minimizing the aerobic spore-forming bacteria that could lead to spoilage of milk and dairy products. Assessment and characterization of this particular flora are of great importance to allow the dairy or food industry to adequately deal with newly arising microbiological problems.

Animals↗
PubMed2005

Fatal family outbreak of Bacillus cereus-associated food poisoning.

Bacillus cereus is a well-known cause of food-borne illness, but infection with this organism is not commonly reported because of its usually mild symptoms. A fatal case due to liver failure after the consumption of pasta salad is described and demonstrates the possible severity of the emetic syndrome.

Adolescent↗
PubMed2004

Bacillus shackletonii sp. nov., from volcanic soil on Candlemas Island, South Sandwich archipelago.

A sample of mossy soil taken from the eastern lava flow of northern Candlemas Island, South Sandwich archipelago, yielded six isolates of aerobic, endospore-forming bacteria. Miniaturized routine phenotypic tests and other observations, amplified rDNA restriction analysis and SDS-PAGE analysis suggested that the strains represent a novel taxon. 16S rDNA sequence comparisons support the proposal of a novel species, Bacillus shackletonii sp. nov., the type strain of which is LMG 18435(T) (=CIP 107762(T)).

Antarctic Regions↗
PubMed2004

Bacillus galactosidilyticus sp. nov., an alkali-tolerant beta-galactosidase producer.

A novel Bacillus isolate from raw milk and four strains from diverse origins that were identified previously as Bacillus lentus, Bacillus firmus and Bacillus circulans showed a high degree of similarity in amplified rDNA restriction analysis, SDS-PAGE and routine phenotypic tests, whilst 16S rDNA sequence comparisons and DNA relatedness data showed that this taxon was different from related Bacillus species. On the basis of these data, Bacillus galactosidilyticus sp. nov. is proposed, with the type strain LMG 17892(T) (=DSM 15595(T)=Logan B2188(T)=MB 800(T)).

Bacillus↗
PubMed2004

Paenibacillus lactis sp. nov., isolated from raw and heat-treated milk.

Endospore-forming bacteria were recovered from individual packages from different processing lines in a dairy plant during a tenacious periodical contamination of their UHT-milk production. Two colony types were seen, one of which was identified as Bacillus sporothermodurans. Analysis of the 16S rRNA gene of the second colony type placed these isolates within the genus Paenibacillus, with Paenibacillus lautus as the closest known relative. Moreover, over 99 % similarity was observed to the 16S rDNA sequence of MB 2035, a strain isolated previously from raw milk during a survey at dairy farms for very heat-resistant spore-forming bacteria. Nine other potentially closely related strains among the dairy farm isolates were found using rep-PCR typing. The taxonomic positions of these 19 isolates were further investigated using 16S rRNA gene sequencing and DNA-DNA hybridizations of representative strains. All 19 isolates shared a high degree of phenotypic similarity and were easily distinguished from closely related members of the genus. Anteiso-C(15 : 0), C(16 : 0) and iso-C(15 : 0) were among the major fatty acids and the genomic DNA G+C content was 51.6-51.7 mol%. Therefore, based on their phenotypic, phylogenetic and genomic distinctiveness, these 19 strains, isolated from both raw and heat-treated milk, are placed in the genus Paenibacillus as Paenibacillus lactis sp. nov. The type strain is MB 1871(T) (=LMG 21940(T)=DSM 15596(T)).

Animals↗
PubMed2004

Paenibacillus cineris sp. nov. and Paenibacillus cookii sp. nov., from Antarctic volcanic soils and a gelatin-processing plant.

Seven strains of aerobic, endospore-forming bacteria were found in soil taken from an active fumarole on Lucifer Hill, Candlemas Island, South Sandwich archipelago, Antarctica, and four strains were from soil of an inactive fumarole at the foot of the hill. Amplified rDNA restriction analysis, 16S rDNA sequence comparisons, SDS-PAGE and routine phenotypic tests support the proposal of two novel species of Paenibacillus, Paenibacillus cineris sp. nov. and Paenibacillus cookii sp. nov., the type strains of which are LMG 18439T (=CIP 108109T) and LMG 18419T (=CIP 108110T), respectively. A further strain, isolated from a gelatin-production process, showed more than 99% 16S rDNA sequence similarity to the proposed P. cookii type strain and, although the gelatin isolate was atypical when compared with the fumarole isolates by repeated element primed-PCR, SDS-PAGE and phenotypic analyses, it was shown by DNA-DNA reassociation studies to belong to the same species. Strains of P. cookii produce spreading growth with motile microcolonies. Both species produce swollen sporangia that are typical for the genus, they both show 97.6% 16S rDNA sequence similarity to Paenibacillus azoreducens, they have 51.5-51.6 mol% G+C in their DNA and their major fatty acid is anteiso-C(15 : 0); however, fatty acids C(16 : 0) and anteiso-C(17 : 0) represent, respectively, 18 and 10 % of the total in P. cineris, but 11 and 20% in P. cookii.

Aerobiosis↗
PubMed2004

Bacillus farraginis sp. nov., Bacillus fortis sp. nov. and Bacillus fordii sp. nov., isolated at dairy farms.

Forty-eight bacterial strains were isolated at dairy farms from raw milk, the milking apparatus, green fodder or feed concentrate after a heat treatment of 30 min at 100 degrees C. In this way, spore-forming bacteria with a very high intrinsic heat resistance were selected for. The aerobic spore-forming isolates were subjected to a polyphasic taxonomical study, including repetitive element sequence-based PCR typing, whole-cell protein profiling, 16S rDNA sequence analysis, DNA-DNA hybridizations, DNA base composition, fatty acid analysis, and morphological and biochemical characteristics. A comparison of the REP- and (GTG)5-PCR and whole-cell protein SDS-PAGE profiles resulted in three clusters of similar strains. Analysis of the 16S rDNA sequences and DNA-DNA relatedness data showed that these clusters represented three novel species. The highest 16S rDNA similarity to a recognized species found for the three groups was around 94% with Bacillus lentus and Bacillus sporothermodurans. Further phenotypic characterization supported the proposal of three novel species in the genus Bacillus, Bacillus farraginis, Bacillus fortis and Bacillus fordii. The respective type strains are R-6540T (=LMG 22081T=DSM 16013T), R-6514T (=LMG 22079T=DSM 16012T) and R-7190T (=LMG 22080T=DSM 16014T); their G+C DNA base contents are 43.7, 44.3 and 41.9 mol%, respectively. Although in variable amounts, a predominance of the branched fatty acids iso-C(15 : 0) and anteiso-C(15 : 0) was observed in all three novel species.

Aerobiosis↗
PubMed2004

Phenotypic and molecular typing of Salmonella strains reveals different contamination sources in two commercial pig slaughterhouses.

This study aimed to define the origin of Salmonella contamination on swine carcasses and the distribution of Salmonella serotypes in two commercial slaughterhouses during normal activity. Salmonellae were isolated from carcasses, from colons and mesenteric lymph nodes of individual pigs, and from the slaughterhouse environment. All strains were serotyped; Salmonella enterica serotype Typhimurium and Salmonella enterica serotype Derby isolates were additionally typed beyond the serotype level by pulsed-field gel electrophoresis (PFGE) and antibiotic resistance profiling (ARP); and a subset of 31 serotype Typhimurium strains were additionally phage typed. PFGE and ARP had the same discriminative possibility. Phage typing in combination with PFGE could give extra information for some strains. In one slaughterhouse, 21% of the carcasses were contaminated, reflecting a correlation with the delivery of infected pigs. Carcass contamination did not result only from infection of the corresponding pig; only 25% of the positive carcasses were contaminated with the same serotype or genotype found in the corresponding feces or mesenteric lymph nodes. In the other slaughterhouse, 70% of the carcasses were contaminated, and only in 4% was the same genotype or serotype detected as in the feces of the corresponding pigs. The other positive carcasses in both slaughterhouses were contaminated by genotypes present in the feces or lymph nodes of pigs slaughtered earlier that day or from dispersed sources in the environment. In slaughterhouses, complex contamination cycles may be present, resulting in the isolation of many different genotypes circulating in the environment due to the supply of positive animals and in the contamination of carcasses, probably through aerosols.

Abattoirs↗
PubMed2004

Assessment of virulence of pigeon isolates of Salmonella enterica subsp. enterica serovar typhimurium variant copenhagen for humans.

Salmonella enterica serovar Typhimurium variant Copenhagen was isolated from 5 of 152 (3.3%) feral pigeons from the city of Ghent (Belgium) and from 26 pooled fecal samples from 114 pigeon lofts (22.8%). These isolates belonged to phage type (PT) 99. Seven of the pigeon isolates were further compared in vitro to five human variant Copenhagen isolates, 2 isolates of PT 208, 1 isolate each of PT 120 and U302, and a nontypeable isolate. No differences in invasiveness in human intestinal epithelial Caco-2 cells were found. The human strains, however, were able to multiply significantly more inside human THP-1 macrophages than the pigeon strains. After inoculation of mice with a pigeon PT 99 strain, high numbers of Salmonella bacteria were shed with the feces, the internal organs were heavily colonized, and the animals showed severe clinical symptoms resulting in death. In conclusion, the less-pronounced ability of the pigeon variant Copenhagen strains to multiply inside human macrophages than human strains as well as the lack of human PT 99 isolates during 2002, despite the relatively high frequency of this PT in the pigeon population, suggest these strains to be of low virulence to humans. However, the high virulence for mice of the tested strain implies that rodents may act as reservoirs.

Animals↗