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Biomedical subjects

F Haesebrouck

Publications and source records attributed to F Haesebrouck.

At least 73 records · Page 4Linked to original sources
PubMed2003

Macrolide and lincosamide resistance in the gram-positive nasal and tonsillar flora of pigs.

Macrolide and lincosamide resistance phenotypes and the presence of the erm(A), erm(B), erm(C), and mef(A) genes were determined in 344 bacterial strains belonging to 34 species and nine genera, isolated from the tonsils and nasal cavities of 2-week- and 6-week-old piglets, derived from four different farms. These piglets had never before been treated with macrolides or lincosamides. Macrolide and lincosamide resistance was most frequently present in Streptococcus and Enterococcus strains, of which over two-thirds were resistant. These genera were followed in decreasing order of resistance frequency by Lactobacillus, Rothia, Staphylococcus, Arcanobacterium, Actinomyces, Pediococcus strains. Only five infrequently occurring species did not show resistance. This high frequency of resistance in nontreated piglets indicates that resistant strains circulate in the herds. In streptococci, enterococci, and Lactobacillus strains, resistance was most often encoded by the erm(B) gene and in staphylococci by erm(A) or erm(C). The erm(B) gene was sporadically detected in other bacterial genera (Actinomyces, Rothia, Aerococcus, Pediococcus). The sequence of the erm(B) gene of 29 strains of 11 pigs originating from the four different farms was determined. This sequence was identical in 12 strains and only differed by 1-6 nucleotides in the other strains, indicating that exchanges of resistance genes might occur between bacterial species and genera belonging to the nasal or tonsillar flora of piglets.

Animals↗
PubMed2003

Phenotypic and genetic characterization of resistance against macrolides and lincosamides in Streptococcus gallolyticus strains isolated from pigeons and humans.

The macrolide and lincosamide (ML) resistance phenotype of 65 pigeon and 30 human Streptococcus gallolyticus strains was determined by the disk diffusion method. Constitutive resistance against the tested antibiotics was seen in 13 human and 28 pigeon strains. Simultaneous screening for the presence of erm(B) and mef(A) genes using PCR revealed that the erm(B) gene was present in 40 out of these 41 phenotypically resistant S. gallolyticus strains while the mef(A) gene was detected in only one resistant and one susceptible human-derived strain. The erm(B) genes of 10 human and 10 pigeon S. gallolyticus strains were sequenced and compared. Four human and seven pigeon strains possessed exactly the same sequence for the erm(B) gene. The sequence of the erm(B) gene of the remaining strains differed in one to five nucleotides. These findings could indicate a possible exchange of resistance genes between human and pigeon strains.

Animals↗
PubMed2003

Description of Enterococcus canis sp. nov. from dogs and reclassification of Enterococcus porcinus Teixeira et al. 2001 as a junior synonym of Enterococcus villorum Vancanneyt et al 2001.

Strains from anal swabs and chronic otitis externa in dogs were shown to be phylogenetically related to the Enterococcus faecium species group. They shared a number of phenotypic characteristics with these species, but they could be easily differentiated by biochemical reactions. In addition, the canine strains were unusual in their nearly complete failure to grow on sodium azide-containing enterococci-selective media and in their Voges-Proskauer reactions (usually negative). By using 16S rRNA sequencing and DNA-DNA hybridization of representative strains, as well as tDNA interspacer gene PCR and SDS-PAGE of whole-cell proteins, the group of canine strains was shown to constitute a novel enterococcal species. The name Enterococcus canis sp. nov. is proposed for this species, with LMG 12316T (= CCUG 46666T) as the type strain. Concurrently, the taxonomic situation and nomenclatural position of Enterococcus porcinus were investigated. As no phenotypic or genotypic differences were found between this species and Enterococcus villorum, the name E. porcinus is considered to be a junior synonym of E. villorum.

Animals↗
PubMed2002

Seroprevalence of Actinobacillus pleuropneumoniae serovars 2, 3 and 9 in slaughter pigs from Belgian fattening farms.

Fifty randomly selected fattening pig herds were studied to investigate the epidemiological characteristics of infections with Actinobacillus pleuropneumoniae serovars 2, 3 and 9, and to identify risk factors for their within-herd seroprevalences. Information about 13 farm characteristics was obtained by means of a questionnaire and used to assess potential risk factors for the percentage of slaughter pigs with antibodies against each of the three serovars. The presence of antibodies was measured with an indirect ELISA. The median within-herd seroprevalence for serovar 2 was 58 per cent (range 0 to 100 per cent), for serovar 3, 53 per cent (range 10 to 95 per cent), and for serovar 9, 35 per cent (range 5 to 100 per cent). All but one farm tested positive for A pleuropneumoniae serovar 2, and all the farms were positive for A pleuropneumoniae serovars 3 and 9. There was a positive association (P < 0.05) between each pair of serovars. The within-herd seroprevalence of serovar 2 was significantly associated with the density of pig herds in the municipality (odds ratio [OR] = 1.60; P < 0.05) and with the absence of preventive medication at the start of the fattening period (OR = 2.77; P < 0.10). No significant risk factors were found for serovar 3. The percentage of pigs positive for serovar 9 was significantly associated with a slaughter date in June (OR = 2.30; P < 0.10) and with herds in which the finishing houses were not divided into separate compartments (OR = 2.99; P < 0.05).

Actinobacillus Infections↗
PubMed2002

Identification and antimicrobial susceptibility of Staphylococcus chromogenes isolates from intramammary infections of dairy cows.

Staphylococcus chromogenes is a highly prevalent species in subclinical mastitis with a well-established impact on somatic cell count. Few data are available on its antimicrobial susceptibility. The objective of this study was three-fold: (1) to evaluate simple identification tests by comparing them with a genomic method; (2) to determine minimal inhibitory concentrations (MICs) of different antibiotics; (3) to search for the presence of important resistance mechanisms and resistance-determining genes.Seventy-three staphylococcal strains, all collected on different dairy farms, were tentatively identified as S. chromogenes based on their lack of hemolysis and their characteristic intermediate DNase activity. The identification of 70 strains was confirmed as S. chromogenes by tRNA intergenic spacer PCR (tRNA PCR). Three strains were identified as S. sciuri, a species that is naturally cloxacillin- and lincomycin-resistant. All 70 S. chromogenes strains were found to be normally susceptible to neomycin, gentamicin, erythromycin, enrofloxacin, and to penicillinase-stable penicillins and cephalosporins, represented in this study by cloxacillin. The latter result was confirmed by the absence of the mecA gene in each of 13 strains in which this gene was searched for. Twenty-seven (38%) strains were penicillinase producers. Three lincomycin-resistant S. chromogenes strains were found to carry the linA gene. It was concluded that S. chromogenes can be identified reliably in routine mastitis bacteriology, and that the only resistance of importance is against penicillinase-susceptible penicillins.

Animals↗
PubMed2002

Identification of a new biotype of Actinomyces hyovaginalis in tissues of pigs during diagnostic bacteriological examination.

Bacterial strains isolated from a large variety of necropsy samples of pigs and previously described as a phenotypical homogeneous group were shown to belong to the species Actinomyces hyovaginalis. This was unexpected because their colonial characteristics, as well as their origins, were very different from those originally reported for the vaginal strains on which the species description of A. hyovaginalis was based. Colonial morphology, as well as fermentation of cellobiose, reactions in hippurate and nitrate and production of beta-glucuronidase, allowed separation of the strains studied here from the vaginal strains. Analysis of tRNA intergenic length polymorphisms (tDNA-PCR), 16S rRNA-gene sequencing and DNA-DNA hybridizations were carried out and led to the proposal of a separate biotype within the species A. hyovaginalis. Since, the strains were isolated from different body sites, this biotype has been designated as the 'general' biotype of A. hyovaginalis, while the strains on which the original species description was based are designated as the 'vaginal' biotype.

Actinomyces↗
PubMed2002

Interactions of Salmonella enterica serovar Muenchen with macrophages of the turtle Trachemys scripta scripta.

Interactions of Salmonella with macrophages have been studied in birds and, most extensively, in mammals. In these homeothermic animals, interactions between Salmonella and macrophages are characterized by the following processes. After macropinocytosis, spacious phagosomes are formed within the macrophage. Partial inhibition of phagosome-lysosome fusion and resistance to the formation of reactive oxygen species and reactive nitrogen intermediates enable the bacterium to survive and even multiply within the host macrophage. Eventually, Salmonella will induce apoptosis of the macrophage. In this study, interactions of peritoneal macrophages of the turtle Trachemys scripta scripta with Salmonella enterica serovar Muenchen were examined in vitro. Turtle macrophages were able to phagocytise Salmonella efficiently at both 30 and 37 degrees C. Exposure of macrophages to Salmonella induced the production of reactive oxygen species, which could be partially suppressed by adding the NADPH oxidase inhibitor diphenylene iodonium. Initially, most of the intracellular bacteria were killed. However, Salmonella proved to be able to persist and multiply inside turtle macrophages at both 30 and 37 degrees C for at least 48 h, despite the production of reactive nitrogen intermediates by inducible NO synthase. Salmonella infection of turtle macrophages killed the phagocytes at both 30 and 37 degrees C. These findings demonstrate that no obvious qualitative differences exist between macrophage-Salmonella interactions from homeothermic animals and from turtles. This indicates that other factors are responsible for the different course of Salmonella infections in homeothermic and poikilothermic hosts.

Animals↗
PubMed2002

Composition of enterococcal and streptococcal flora from pigeon intestines.

AIMS: To identify the streptococcal and enterococcal components of the microflora from pigeon intestines to species level by tDNA-intergenic polymerase chain reaction. METHODS AND RESULTS: Gram-positive coccal strains were isolated from the intestines or faeces of 50 different pigeons, all from different lofts, on Columbia CNA blood agar. Sodium azide-sensitive enterococci were found to constitute the major coccal members of the intestinal flora of pigeons. Forty-two of 69 isolates were identified as Enterococcus columbae (84% of animals tested positive), while E. cecorum was encountered in 28% of all animals (14 isolates). Minor species (less than 10% of pigeons positive) were E. faecalis, E. faecium, E. gallinarum, E. casseliflavus, Streptococcus alactolyticus and Strep. gallolyticus. Contrary to the species description of E. columbae and E. cecorum, some of the strains were found to be motile. Certain other minor differences with the species description of E. columbae are also indicated. CONCLUSIONS: Enterococcus columbae is the major Gram-positive facultatively anaerobic component of the pigeon intestinal flora. Certain phenotypic characteristics differ from the original species description. The potentially pathogenic Strep. gallolyticus is a minor component of the microflora. Enterococcus faecium and E. faecalis are rare in pigeons. SIGNIFICANCE AND IMPACT OF THE STUDY: The enterococcal and streptococcal flora of pigeons is composed of mainly host-specific bacteria. These are not likely to act as zoonotic pathogens nor as carriers of antibiotic resistance determinants possibly spreading to humans.

Animals↗
PubMed2002

Differentiation and identification of Enterococcus durans, E. hirae and E. villorum.

AIMS: To compare different tests in the identification of Enterococcus durans, E. hirae and E. villorum strains. These bacteria belong to the E. faecium species group and are phylogenetically closely related, as evidenced by 16S rRNA sequence homologies of over 98.8%. METHODS AND RESULTS: Sodium dodecyl sulphate-polyacrylamide gel electrophoresis analysis of whole-cell protein, tRNA interpacer polymerase chain reaction (PCR) and arbitrarily-primed (D11344-primed AP) -PCR analysis correctly identified all three species in a collection of strains from very diverse origins. In contrast, biochemical reactions only allowed the unequivocal differentiation of the three species as a group from the other enterococci. Within this group, D-xylose acidification can be used to differentiate E. villorum, but exceptions occur. Strains highly susceptible to clindamycin can be identified as E. durans, but many strains of this species cannot be differentiated from E. hirae and E. villorum due to acquired resistance. CONCLUSIONS: Despite their close relationship, E. durans, E. hirae and E. villorum can be differentiated by genomic methods and by whole-cell protein analysis. SIGNIFICANCE AND IMPACT OF THE STUDY: Only a minority of strains of these three enterococcal species can be identified reliably by the currently available and commonly applied phenotypic tests.

Animals↗
PubMed2002

Characterization of yellow-pigmented and motile enterococci isolated from intestines of the garden snail Helix aspersa.

AIMS: Enterococci associated with garden snails (Helix aspersa) were studied in order to obtain reliable species identification and characterization. METHODS AND RESULTS: Twelve yellow-pigmented and motile enterococci, isolated from the intestines of garden snails, were phenotypically close to Enterococcus casseliflavus, but they showed certain unusual biochemical characteristics. tRNA intergenic length polymorphism analysis (tDNA-PCR) divided all strains studied into two groups, in full agreement with biochemical test results. 16S rDNA sequencing, DNA base composition analysis and DNA-DNA hybridization results showed unambiguously that the enterococci studied belonged to the species Ent. casseliflavus. The representative strains of described ecovars were deposited in the Czech Collection of Microorganisms (CCM) as Ent. casseliflavus CCM 4868, 4869, 4870 and 4871. CONCLUSIONS: Enterococcus casseliflavus associated with garden snails can be subdivided into groups. SIGNIFICANCE AND IMPACT OF THE STUDY: Enterococcus casseliflavus differs from other enterococcal species in that it is typically associated with plants, soil, water and invertebrate animals. The different groups that can be found in these widely occurring bacteria are possibly source-specific ecovars, as exemplified by the Ent. casseliflavus inhabiting the intestines of snails.

Animals↗
PubMed2002

Patterns of Mycoplasma hyopneumoniae infections in Belgian farrow-to-finish pig herds with diverging disease-course.

Patterns of Mycoplasma hyopneumoniae (Mh) infections were investigated in five clinically infected herds and in five herds subclinically infected with Mh. In the clinically infected herds, housing and management conditions were good whereas these conditions were poor in the subclinically infected herds. In each herd, serum antibodies against Mh were detected in pigs of different ages and nasal swabs were taken for Mh detection using nested PCR (nPCR). The percentage of seropositive pigs in the clinically infected herds increased from 8% in pigs of 9 weeks to 52% in pigs of 18 weeks and seroconversion was most shown between 12 and 15 weeks. In the subclinically infected herds, the percentages increased from 2 to 24% and most of the pigs became seropositive between 15 and 18 weeks. The percentage of nPCR positive pigs at 6 weeks was 16 and 0% in the clinically and subclinically infected herds, respectively. The results demonstrate that the seroprevalences were higher in the clinically infected herds and that most of the pigs became infected with Mh at a younger age. It can be concluded that additional factors different from housing and management, like differences among Mh strains, may determine the infection pattern of Mh and the clinical course of the infection.

Animal Husbandry↗
PubMed2002

Failure of a low virulence Streptococcus gallolyticus serotype 1 strain to immunize pigeons against streptococcosis.

Ten pigeons were inoculated intravenously with the low virulence Streptococcus gallolyticus strain PDH 827, which belongs to serotype 1, supernatant phenotype A(-)T2. The birds did not develop clinical disease but shed S. gallolyticus in their faeces, and antibodies against the bacterium were detected in post-inoculation plasma samples of all birds. Seven weeks later, these pigeons, as well as 14 control pigeons, were challenged intravenously with the highly virulent S. gallolyticus strain STR 357, which also belongs to serotype 1 but to the supernatant phenotype A(+)T1. Post-inoculation morbidity in the immunized group amounted to 90%, demonstrating that no protective immunity had been built up after the first infection. These findings indicate that serotype-specific antigens are not, or at least not solely, involved in induction of protection against S. gallolyticus septicaemia in pigeons.

Animals↗
PubMed2002

The effect of Ornithobacterium rhinotracheale vaccination of broiler breeder chickens on the performance of their progeny.

The effect of Ornithobacterium rhinotracheale vaccination of broiler breeders on antibody titres and performance of breeders and broilers was investigated. O. rhinotracheale antibody titres and performance data were recorded from 16 different broiler breeder flocks and from 79 of their broiler progeny flocks. Eight breeder flocks were vaccinated with an inactivated O. rhinotracheale vaccine while the other eight breeder flocks were left unvaccinated against this bacterium. Following vaccination, mean O. rhinotracheale antibody titres in the breeders rose to a 6.5 log(2) units higher value than in unvaccinated breeders, and remained at a mean titre of 15 log(2) units during the entire production period. This resulted in significantly higher maternal antibody titres against O. rhinotracheale in the broiler progeny of vaccinated breeder flocks compared with the offspring of unvaccinated flocks. Statistical analyses revealed no differences in performance between vaccinated and unvaccinated breeders. There was a significantly lower mean mortality rate and higher mean production index in the broilers derived from vaccinated breeders.

Animals↗
PubMed2002

Prevalence of antimicrobial resistance among pigeon isolates of Streptococcus gallolyticus, Escherichia coli and Salmonella enterica serotype Typhimurium.

Thirty-three Streptococcus gallolyticus, 60 Escherichia coli and 18 Salmonella enterica serotype Typhimurium var. Copenhagen strains isolated from homing pigeons (Columba livia) were tested for susceptibility to the antimicrobials most commonly used to treat pigeons. Minimal inhibitory concentrations were determined using the agar dilution technique. Aminoglycosides (gentamicin and kanamycin), trimethoprim and flumequine were relatively inactive against the streptococci tested. Acquired tetracycline resistance amounted to 85%, and lincomycin and macrolide (erythromycin) resistance to 48 and 45%, respectively. Fluoroquinolone (enrofloxacin) resistance was found in four S. gallolyticus strains. All strains were susceptible to ampicillin. With the E. coli strains, resistance was found to all antibiotics tested. Over one-half of them were resistant to tetracycline and to broad-spectrum penicillins (ampicillin); however, none showed extended spectrum beta-lactamase activity, implying that the cephalosporins (ceftiofur) remained active. Resistance to trimethoprim, aminoglycosides and fluoroquinolone ranked next. In contrast to the S. gallolyticus and E. coli strains, the S. enterica strains were susceptible to all the antimicrobials tested.

Animals↗
PubMed2002

An alternative model to study the association of rainbow trout (Oncorhynchus mykiss L.) pathogens with the gill tissue.

This study describes the development of a trout gill perfusion model, consisting of an excised branchial arch from rainbow trout (Oncorhynchus mykiss L.), perfused via the afferent branchial artery and suspended in a circular organ chamber filled with Ringer solution. Different perfusion fluids were tested: Ringer, Cortland, Ringer + procaine, Ringer + adrenalin, Cortland + procaine, Cortland + adrenalin and Cortland + dextran 1%. The latter perfusion fluid proved to be satisfactory, maintaining the gill tissue in a healthy condition outside the body of the fish for at least 180 min. Using this model, the interaction of damaging agents with the trout gill tissue may be studied under carefully controlled conditions. The trout gill perfusion model leads effectively to a reduction in the number of experimental animals to be used and also involves an elimination of pain and/or suffering, which is as good as complete.

Animal Testing Alternatives↗