Revised taxonomy and nomenclature of rodent Pasteurellaceae: Implications for monitoring

Pasteurellosis is a well-recognized disease with similar pathology in all laboratory rodent species. Pasteurella pneumotropica is the most frequently mentioned member of the Pasteurellaceae isolated from mice and rats. Numerous other Pasteurellaceae taxa have been obtained from mice, rats, and other rodent species. Recently, rodent Pasteurellaceae have been submitted to comprehensive genetic and phenotypic (polyphasic) taxonomic studies. As a result they are now classed within six validly published new genera, namely Cricetibacter, Mesocricetibacter, Mannheimia, Muribacter, Necropsobacter, and Rodentibacter. All previously used names such as P. pneumotropica have become obsolete. The new classification forms a firm basis for the correct phenotypic identification of Pasteurellaceae from laboratory animals and for the selection of strains for pathogenicity studies. Consequences of taxonomic changes notably involve molecular methods used for the detection of Pasteurellaceae infection in laboratory animal colonies. Testing may be done using primer sets that detect all Pasteurellaceae taxa or sets developed to detect host-specific members of the family.

Recommendations for the housing of macaque monkeys

A multidisciplinary working group was formed to make recommendations for housing of macaques under laboratory conditions in the Netherlands. The group concluded that long-term individual caging leads to persistent abnormal behaviour. Therefore, individual housing is regarded as acceptable only for special reasons which counter-balance the adverse effects of isolation. Guidelines are given for developing more satisfactory social housing systems. Cages used in individual as well as social housing should meet certain spatial and other requirements to ensure a certain amount of diversion, freedom of movement and safety. Since the recommendations represent the opinion of experts in certain aspects of animal husbandry, the report can be used as a legal reference under the Animal Experiments Act.

Detection of antibodies to Streptobacillus moniliformis in rats by an immunoblot procedure

An immunoblot (IB) technique for detecting antibodies to Streptobacillus moniliformis in rat sera was evaluated. Immune sera to three S. moniliformis strains showed a similar reactivity pattern with both autologous and homologous antigens in the 18–87 kDa range. Using a rat S. moniliformis strain as the antigen, a similar reactivity pattern was found with sera from rats infected experimentally with S. moniliformis and sentinels. Two to five proteins were detected in the 32–55 kDa range. Over a period of 2.5 years, 27/133 rat serum panels submitted for routine monitoring yielded one or more S. moniliformis enzyme-linked immunosorbent assay (ELISA)-positive samples. In one of these 27 panels, sera showed an IB reactivity pattern resembling that observed with immune sera and with sera from infected and exposed rats. S. moniliformis was confirmed in the colony by both culture and polymerase chain reaction (PCR). Sera from the remaining 26 ELISA-positive serum panels frequently showed activity to a 57 kDa antigen but not more than one antigen was detected in the 32–55 kDa range. We conclude that the IB can be used as a confirmatory test for the detection of S. moniliformis infection in ELISA-positive rats.

Frequent major errors in antimicrobial susceptibility testing of bacterial strains distributed under the Deutsches Krebsforschungszentrum Quality Assurance Program

The Quality Assurance Program (QAP) of the Deutsches Krebsforschungszentrum (DKFZ) was a proficiency testing system developed to service the laboratory animal discipline. The QAP comprised the distribution of bacterial strains from various species of animals for identification to species level and antibiotic susceptibility testing (AST). Identification capabilities were below acceptable standards. This study evaluated AST results using the DKFZ compilations of test results for all bacterial strains showing the number of participants reporting the strain as resistant (R), sensitive (S) or intermediate susceptible (I) to each antibiotic substance used. Due to lack of information about methods used, it was assumed that what the majority of the participants reported (R or S) was the correct test result and that an opposite result was a major error (ME). MEs occurred in 1375 of 14,258 (9.7%) of test results and ME% ranged from 0% to 23.2% per bacterial group-agent group combination. Considerable variation in MEs was found within groups of bacteria and within groups of agents. In addition to poor performance in proper species classification, the quality of AST in laboratory animal diagnostic laboratories seems far below standards considered acceptable in human diagnostic microbiology.

Comparison of polymerase chain reaction primer sets for amplification of rodent Pasteurellaceae

Monitoring of rodents for Pasteurellaceae infection may be carried out by the polymerase chain reaction (PCR). We tested which of 17 rodent Pasteurellaceae strains were detected by three PCR primer sets. By phylogenetic analysis, 12 strains were assigned to the Rodent cluster and five strains to other clusters, namely the Somnus cluster, Pasteurella sensu stricto, Actinobacillus sensu stricto, the Mannheimia and Rossii cluster. A primer set developed to detect biotype Heyl [Pasteurella] pneumotropica produced amplicons from three strains and appeared specific for this taxon. A primer set developed to detect biotype Jawetz [P.] pneumotropica produced amplicons from the [P.] pneumotropica type strain and two other strains within the Rodent cluster. A primer set as described by Bootz and his co-workers (Bootz F, Kirschnek S, Nicklas W, Wyss SK, Homberger FR. Detection of Pasteurellaceae in rodents by polymerase chain reaction analysis. Lab Anim Sci 1998;48:542-6) for the detection of all Pasteurellaceae indeed detected all bacterial strains examined. Bootz's primer set should be used to monitor rodents for Pasteurellaceae infection by PCR as FELASA recommends the monitoring of rodents for all Pasteurellaceae taxa. Health monitoring reports should specify the primer set(s) used for PCR testing rodents for Pasteurellaceae infection.

Identification of bacterial strains by laboratories participating in the Deutsches Krebsforschungszentrum quality assurance programme

The quality assurance programme (QAP) of the Deutsches Krebsforschungszentrum (DKFZ) is a proficiency testing system developed to service the laboratory animal discipline. QAP comprises the quarterly distribution of two bacterial strains originating from various species of animals for identification to the species level and antibiotic susceptibility testing. We compared identification results reported by QAP participants over the years 1996-2004 with those obtained by the Dutch Bacterial Diagnostics reference laboratory on 68 samples comprising 71 bacterial strains and a fungus. Significant differences were found in the frequency of reported and correct identifications when bacteria were assigned to different groups based on morphology by Gram stain and on origin (animal versus environmental, rodent and rabbit versus other animal species, pathogen versus non-pathogens). Rodent and rabbit pathogens yielded 73% correct identifications, and with all bacterial strains only 60% of the identifications were correct. We assume that most QAP participants were from laboratory animal diagnostic laboratories. If this is true, the capabilities of laboratories in the laboratory animal discipline to correctly identify bacterial species are well below what are considered acceptable limits for human diagnostic laboratories. The distribution of cultured bacteria circumvents the most difficult step in the microbiological monitoring of animals, namely primary culture from clinical samples. We propose to set up a QAP that comprises the distribution of specimens mimicking clinical samples normally submitted to laboratory animal diagnostic laboratories.

Evaluation of antigen panels for ELISA monitoring of mouse colonies for antibodies to Pasteurellaceae

Pasteurellaceae infection in mice may be monitored by the detection of serum antibody using enzyme-linked immunosorbent assay (ELISA). We re-evaluated our standard antigen panel comprising Pasteurella pneumotropica and a V-factor requiring Haemophilus species (strain H21) by studying their serological relationship with Actinobacillus muris and 'Haemophilus influenzae-murium'. Serologically, A. muris and 'H. influenzae-murium' were found to be unrelated and to differ from P. pneumotropica and Haemophilus strain H21. These four antigens were used for monitoring breeding and experimental mouse colonies for a period of four years. The addition of 'H. influenzae-murium' antigen to the standard panel of antigens significantly increased the proportion of sera and serum panels showing anti-Pasteurellaceae antibody activity, but the addition of A. muris antigen did not.

Elevated plasma chemokine CCL18/PARC in β-thalassemia

Plasma CCL18/PARC, a member of the CC chemokine family, has been found to be several ten-fold increased in symptomatic Gaucher type I patients. Elevated plasma chitotriosidase levels are a well-known abnormality in Gaucher patients, however, its diagnostic use is limited by the frequent genetic deficiency in the protein. Like the situation in Gaucher disease, lipids accumulate in macrophages of patients suffering from beta-thalassemia, and, in both conditions, increased chitotriosidase levels occur. We here report that plasma CCL18/PARC is also significantly increased in patients with beta-thalassemia major (range 76.8-4977.8, median=650.8 ng/ml, n=36 and control range 10-72, median=33 ng/ml n=36 respectively, P<0.001). The CCL18/PARC levels are lower than in Gaucher patients (range 174.8-10798.7, median 2538.2 ng/ml, n=28, P<0.001). In our cohort of beta-thalassemic patients, CCL18/PARC showed a significant negative correlation to iron chelation therapy and a significant positive correlation to ferritin and chitotriosidase levels, the latter only in the patients with the wild type genotype for the enzyme. Our study demonstrates that beta-thalassemic patients have increased CCL18/PARC levels that could be of value in monitoring iron overload and compliance to therapy.

Rat strains differ in antibody response to natural Haemophilus species infection

Antibody response to Haemophilus species in rat strains was monitored by enzyme-linked immunosorbent assay (ELISA) using antigens of two Haemophilus strains and a Pasteurella pneumotropica strain. Five rat strains from a breeding colony naturally infected by Haemophilus were significantly different in ELISA antibody activity and in the number of seropositive animals. BN and RP rats were (relatively) high and low responders, respectively and BUF, LEW and WAG rats were intermediate. In a second study, five rat strains were exposed to Haemophilus-infected rats, and, after six weeks, were also significantly different in ELISA antibody activity and in numbers of seropositive animals. Here, BN and LEW rats were (relatively) high and low responders, respectively, and BD IX, F344 and WKY rats were intermediate.

PCR for the detection of Streptobacillus moniliformis

Streptobacillus moniliformis is a Gram-negative bacterium found in various laboratory animal species and is the cause of rat bite fever and Haverhill fever in man. In order to evaluate a polymerase chain reaction (PCR) for the detection of this zoonotic bacterium in animal tissues a set of primers was designed based on the DNA base sequence of part of the 16S rRNA gene from 11 S. moniliformis strains. The PCR detected as few as 2-6 copies of S. moniliformis DNA. A 296 bp DNA fragment was amplified from S. moniliformis strains from rodents, humans and turkeys. Amplicons of about the same size were obtained from Fusobacterium necrogenes and Sebaldella (Bacteroides) termitidis but Bfa I treatment of these amplicons did not result in the S. moniliformis specific 130 bp DNA fragment. The in silico evaluation of 14 additional Fusobacterium spp. and 12 unculturable phytoplasmas indicated that none is likely to give rise to confusing amplicons or DNA fragments. The PCR detected S. moniliformis infection in all four orally- and four intravenously-infected C57BL/6 mice and the bacterium was cultured from all but one mouse. The PCR detected S. moniliformis infection in all 12 orally-infected WU rats, and in five of eight rats exposed to natural infection. Enzyme linked immunosorbent assay (ELISA) and PCR were equally successful in detecting infection in rats but S. moniliformis was not detected by using culture.

Quasisteady aero-acoustic response of orifices

The low frequency response of orifices (slit, circular diaphragm, and perforated plate) in the presence of mean flow is well predicted by a quasisteady theory. A refinement is brought to the theory by considering a Mach number dependent vena contracta coefficient. The measurements of the vena contracta coefficient of a slit agree well with the simple analytical expression existing in the case of the Borda tube orifice. The measured scattering matrix coefficients do not depend strongly on the geometry of the element. If the frequency is increased the moduli remain relatively unaffected while the arguments exhibit a complex behavior which depends on the geometry. From these considerations an anechoic termination efficient at high mass flow is designed.

Transmission of rat and guineapig Haemophilus spp. to mice and rats

Mice and rats, free from Pasteurellaceae, were exposed to Haemophilus spp. (V-factor dependent Pasteurellaceae) by housing in proximity to infected rats or guinea pigs, and monitored by culture and enzyme-linked immunosorbent assay (ELISA) for cross infection. A minority of mice became infected when exposed to Haemophilus-infected rats but none when exposed to guinea pigs. Rats were readily infected when exposed to Haemophilus-infected guinea pigs or rats. Although Pasteurellaceae infections are commonly considered as host specific, our data show that Haemophilus spp. can cross the species barrier from rats to mice and from guinea pigs to rats.

Comparison of assays for antibodies to Encephalitozoon cuniculi in rabbits

Two indirect immunofluorescence (IIF) assays, two enzyme-linked immunosorbent assays (ELISAs) and the carbon immunoassay (CIA) for determination of antibodies to Encephalitozoon cuniculi were compared using 210 sera of rabbits, 135 of which originated from seven infected colonies, while 75 originated from four uninfected colonies. There was no evidence of a difference between the different assays with respect to the number of positive sera. There was a clear correlation between the quantitative response measured by IIF and CIA and the other assays, and between both IIF tests, while no such correlation was found in the quantitative response measured by ELISAs, which might be explained by the less quantitative nature of the ELISA. Therefore quantitative determination of antibodies to E. cuniculi should be performed by IIF and not by ELISA. The nosographic sensitivities N1 and specificities N2 of the assays were > or = 0.94 and > or = 0.97 respectively. Small differences in N1 and N2 between the assays, although not statistically significant, were responsible for differences in the calculated predictive values of a positive test and of a negative test. As expected, the magnitude of these differences depended on the fraction of positive sera sampled from a given colony. There was strong evidence of such a difference between the fraction of positive sera found in different colonies, but the sample size from some colonies was too small to allow any conclusion, whether this was due to differences in the prevalences of the infection in the colonies or something else. We conclude that any of the assays will be suitable for the routine health monitoring of laboratory rabbit colonies for E. cuniculi infection, as recommended by the Federation of European Laboratory Animal Science Associations.

Growth medium affects the cellular fatty acid composition of Pasteurellaceae

We studied the cellular fatty acid composition of 10 Actinobacillus (A.) and Pasteurella (P.) reference strains grown on 2 types of agar by the MIDI Microbial Identification System (MIS). A. capsulatus, A. equuli, A. lignieresii, A. ureae, A. dagmatis, P. gallinarum, P. haemolytica, P. multocida, P. pneumotropica biotypes Heyl and Jawetz were grown on GC agar supplemented with ascitic fluid and X and V factor (Levinthal's agar = LA agar) or GC agar supplemented with vitox and hemoglobin (VH agar) on 3 to 7 and 7 to 16 occasions respectively and fatty acid methylester (FAME) profiles were submitted to principal component analysis (PCA). All Pasteurellaceae strains showed FAME profiles typical for the family. Maximum coefficients of variation of the percentage of the 3 major FAMEs 14:0, 16:0, and 16:1 cis were 0.03, 0.03 and 0.03 for Pasteurellaceae strains grown on VH agar and 0.09, 0.17 and 0.09 respectively for strains grown on LA agar. PCA of FAME profiles obtained with growth from LA agar generally did not allow species separation of the Pasteurellaceae but most species were clearly discriminated by PCA when they were grown on VH agar. Our findings indicate that the growth medium had a significant effect on the reproducibility of fatty acid profiling in Pasteurellaceae and that PCA of fatty acid data obtained under standardized growth conditions may discriminate Pasteurellaceae species.

Serological relationship of some V-factor dependent Pasteurellaceae (Haemophilus sp.) from guineapigs and rabbits

Culture of guinea pig and rabbit respiratory tracts for bacteria using X- (haemin) and V- (NAD) factor in agar media detected infection by V-factor dependent Pasteurellaceae (Haemophilus sp.) in three colonies of guinea pigs and a group of rabbits. The 12 Haemophilus strains comprised three API NH codes classed as Haemophilus parainfluenzae and two codes classed as Haemophilus aphrophilus/paraphrophilus. Six cell wall lipid profiles were detected, but these were not related to API NH codes. Both bacteriological properties were used to select strains for serological studies but any relationship between bacteriological and serological properties of the Haemophilus strains was not evident. Varying serological relationships occurred between the newly isolated Haemophilus strains, [Pasteurella] pneumotropica NCTC 8284 and Haemophilus strains previously isolated from rats.

Mutual viral and bacterial infections after housing rats of various breeders within an experimental unit

Fifteen athymic rat strains from 11 breeding colonies were housed within an experimental facility for an immunological study. Health status records supplied with 14 of the strains listed infections by Kilham's rat virus (KRV), Clostridium piliforme (Bacillus piliformis) and Pasteurella pneumotropica for 2, 2 and 1 colonies respectively. In sera taken previous to the study from euthymic rats of 10 strains, antibodies to KRV were detected in 3 strains, to Pneumonia virus of mice (PVM), Rat corona virus (RCV) and Sendai virus in one strain each and to P. pneumotropica in 2 strains. Only 2 of the KRV infections had been reported by the supplier. During the study rats of all 10 strains developed antibodies to 2-4 of viral antigens. Eight out of 10 rat strains seroconverted to 1-5 of the antigens C. piliforme (B. piliformis), Bordetella bronchiseptica, Haemophilus spp., P. pneumotropica and Streptobacillus moniliformis. Two rat strains housed in filtertop cages did not develop antibodies to bacterial antigens. The potential detrimental effects of intercurrent infections on the outcome of the comparative immunological study are discussed.

An enzyme-linked immunosorbent assay (ELISA) for monitoring rodent colonies for Pasteurella pneumotropica antibodies

An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of Pasteurella pneumotropica antibodies in the sera of rats, mice, hamsters and Mastomys. P. pneumotropica from mice and rats showed cross-reactivity. The ELISA using P. pneumotropica NCTC 8284 detected more infected animals than selective culture in groups of rodents from which P. pneumotropica, Haemophilus sp and/or Actinobacillus sp were cultured. Cross reactivity between P. pneumotropica NCTC 8284 and haemophilus and actinobacillus isolates were not studied.

Reclassification of 30 Pasteurellaceae strains isolated from rodents

Thirty Pasteurellaceae strains isolated from gerbil, guineapig, hamster, mouse, muskrat and rat were reinvestigated and reclassified after comparison with reference strains. Strains originally described as Pasteurella pneumotropica were reclassified as [Pasteurella] pneumotropica Heyl biotype (7), [P.] pneumotropica Jawetz biotype (1), Pasteurella dagmatis (1) or Taxon 22 (2). Strains previously reported as Actinobacillus sp. were reclassified as [P.] pneumotropica biotype Jawetz (3), P. dagmatis (3) or Taxon 6 (7). Strains earlier described as Pasteurella gallinarum were renamed as SP group pasteurella (4) or Taxon 25 (2). Some of these reclassified Pasteurellaceae have not been reported previously in rodents. The present findings underline the importance of extended characterization of isolates and comparison with references strains to avoid misclassification within the family Pasteurellaceae Pohl 1981.

Serological studies of Corynebacterium kutscheri and coryneform bacteria using an enzyme-linked immunosorbent assay (ELISA)

An enzyme-linked immunosorbent assay (ELISA) to measure Corynebacterium kutscheri antibodies in mice and rats was developed. Seven C. kutscheri isolates showed considerable serological relationship, but Japanese isolates differed from the British isolates. The ELISA appeared specific since C. kutscheri antigen did not react with antisera against 8 heterologous coryneform species. Antibodies to C. kutscheri were to a limited extent absorbed by autologous and homologous antigen, but not at all by the heterologous coryneform species. In naturally infected wild Rattus norvegicus and laboratory NA rats, the ELISA demonstrated high ODs to C. kutscheri.

Multifactorial analysis of antibiotic sensitivity of Bordetella bronchiseptica isolates from guineapigs, rabbits and rats

The possible relationship between antibiotic sensitivity of B. bronchiseptica isolates and host species was examined. Growth inhibition of 11 B. bronchiseptica isolates from guineapigs, 7 from rabbits and 3 from rats by a variety of antibiotics incorporated in paper disks, was tested. To seek possible relationships among the various antibiotic sensitivities, we submitted our datamatrix to principal component analysis and subsequently to cluster analysis. This approach showed the existence of close clustering as well as highly specific antibiotic sensitivities. In order to test the presumed relationship between antibiotic sensitivity profiles of the B. bronchiseptica isolates and host species of origin, the same datamatrix was submitted to discriminant analysis. Antibiotic sensitivity profiles of the isolates were not clearly related to host species.

An enzyme-linked immunosorbent assay (ELISA) for monitoring antibodies to SP group Pasteurellaceae in guineapigs

Cross-reactivity studies with Pasteurellaceae from guineapigs revealed 5 serologically distinct groups, comprising Pasteurella multocida, Sp group bacteria, SP-like bacteria, Pasteurella pneumotropica and an actinobacillus-like bacterium. Guineapig Pasteurellaceae differed serologically from mouse-derived P. pneumotropica NCTC 8284. An enzyme-linked immunosorbent assay (ELISA) using SP group antigen, developed to monitor 'natural' infections by SP group Pasteurellaceae in guineapigs, detected significantly more infection than did cultivation, and was found superior to an ELISA performed with P. pneumotropica NCTC 8284.

Interlaboratory comparison of enzyme-linked immunosorbent assay (ELISA) and indirect immunofluorescence (IIF) for detection of Bordetella bronchiseptica antibodies in guinea pigs

Thirty-nine guinea pigs were examined for Bordetella bronchiseptica infection by culture and serology, using the enzyme-linked immunosorbent assay (ELISA) and the indirect immunofluorescence (IIF) test. Each serological method detected evidence of B. bronchiseptica infection in more guinea pigs than did culture. IIF using an antigen prepared from a mouse isolate of B. bronchiseptica detected fewer infected guinea pigs than when performed with antigens prepared from B. bronchiseptica isolates from a rat, a dog and a guinea pig. ELISA and IIF detected a comparable incidence of infection. Cross-reactivity was investigated further by carrying out ELISAs using 5 antigens prepared from B. bronchiseptica isolates from different species and antiserum to these antigens raised in non-infected guinea pigs.

Colonization and antibody response in mice and rats experimentally infected with Pasteurellaceae from different rodent species

Mice and rats were experimentally infected with Pasteurellaceae isolated from mice, rats, hamsters and gerbils. Mice and rats were most heavily colonized by strains originally isolated from mice and rats respectively, and to a lesser extent by Pasteurellaceae from hamsters and gerbils. Colonization was generally accompanied by seroconversion. Gross pathology of the lungs was not observed. We conclude that Pasteurellaceae-free SPF mice and rats can be colonized by members of this bacterial family present in other rodent species.

An enzyme-linked immunosorbent assay (ELISA) for monitoring guineapigs and rabbits for Bordetella bronchiseptica antibodies

An enzyme-linked immunosorbent assay (ELISA) for monitoring antibodies specific to Bordetella bronchiseptica in guineapigs and rabbits was developed. In conventional and SPF colonies of guineapigs and rabbits, the ELISA was equally successful in detecting infected animals when compared to selective cultivation from the respiratory tract. The ELISA showed a sensitivity of 100% and a specificity of 90% in guineapigs. In rabbits the sensitivity and specificity of the ELISA were 97% and 91% respectively. In rabbit sera from infected colonies, ELISA activity showed a statistically significant correlation with titres obtained in the micro-agglutination test. Since serologically unrelated strains of the bacterium exist, the monitoring of animals for B. bronchiseptica infection by ELISA should be performed with various antigens.

An enzyme-linked immunosorbent assay (ELISA) for monitoring rodent colonies for Streptobacillus moniliformis antibodies

An enzyme-linked immunosorbent assay (ELISA) to measure Streptobacillus moniliformis antibodies in mice and rats was developed. Twelve S. moniliformis strains originating from cases of rat-bite fever and Haverhill fever in man and from various rodent species, showed considerable serological relationship. The ELISA appeared specific since antibodies to S. moniliformis were absorbed by autologous and homologous antigen, but not by heterologous bacterial antigens. Acholeplasma laidlawii showed partial serological relationship with S. moniliformis. The ELISA was validated using experimental infections in mice and rats. These studies and observations in naturally infected feral rats, confirmed that S. moniliformis is difficult to grow on primary isolation, and that the ELISA for S. moniliformis antibodies revealed more contaminated animals than culture.

Hemagglutination by Pasteurellaceae isolated from rodents

Pasteurellaceae notably P. pneumotropica, have been associated with severe outbreaks of respiratory disease in several species of rodents. Host-specific parasitism of Pasteurellaceae in rodents has hardly been studied. Since host tropism in many bacteria involves adhesive mechanisms, we examined the hemagglutinating (HA) properties of 44 isolates from different rodent species (mouse (15) rat (8), hamster (9), gerbil (10) and Mastomys (2)). Only 13 mouse isolates and the 2 Mastomys isolates hemagglutinated human (type O Rh+) and canine red blood cells (RBCs). No HA was found using RBCs from 10 other animal species. HA was not inhibited by simple sugars and glycoconjugates, but was completely inhibited by heating of bacterial cells for 10 min at 80 or 100 degrees C, partially inhibited by glutaraldehyde and inhibited in a dose-dependent mode by NaIO4, suggesting the involvement of bacterial polysaccharide structures in the HA process. Enrichment procedures did not reveal the presence of HA- subpopulations in HA+ isolates or the presence of HA+ subpopulations in HA- isolates. Electron microscopy revealed the presence of fimbriae both in HA+ and HA- isolates. A regularly structured (RS) layer was detected on cells of part of the HA+ isolates only. Our results suggest that Pasteurellaceae of mice and Mastomys may be related and differ from isolates isolated from other rodent species.

Isolation of peroxisome assembly mutants from Saccharomyces cerevisiae with different morphologies using a novel positive selection procedure

We have developed a positive selection system for the isolation of Saccharomyces cerevisiae mutants with disturbed peroxisomal functions. The selection is based on the lethality of hydrogen peroxide (H2O2) that is produced in wild type cells during the peroxisomal beta- oxidation of fatty acids. In total, 17 mutants having a general impairment of peroxisome biogenesis were isolated, as revealed by their inability to grow on oleic acid as the sole carbon source and their aberrant cell fractionation pattern of peroxisomal enzymes. The mutants were shown to have monogenetic defects and to fall into 12 complementation groups. Representative members of each complementation group were morphologically examined by immunocytochemistry using EM. In one mutant the induction and morphology of peroxisomes is normal but import of thiolase is abrogated, while in another the morphology differs from the wild type: stacked peroxisomal membranes are present that are able to import thiolase but not catalase. These mutants suggest the existence of multiple components involved in peroxisomal protein import. Some mutants show the phenotype characteristic of glucose-repressed cells, an indication for the interruption of a signal transduction pathway resulting in organelle proliferation. In the remaining mutants morphologically detectable peroxisomes are absent: this phenotype is also known from fibroblasts of patients suffering from Zellweger syndrome, a disorder resulting from impairment of peroxisomes.

Isolation of Streptobacillus moniliformis from the middle ear of rats

Streptobacillus moniliformis was isolated from the middle ear of 9 of 16 rats used for otological studies. Examination of rat sera for the presence of anti-Streptobacillus moniliformis antibodies using an ELISA technique resulted in 15 seropositive animals. The source of the S. moniliformis infection was not determined.

Inactivation of staphylococcal enterotoxins by heat and reactivation by high pH treatment

Inactivation of staphylococcal enterotoxins (SE) added to different media upon heat treatment (80 degrees C or 100 degrees C for 10 min) and reactivation of inactivated SE was studied. In gelatin (pH 4.0), lettuce extract, peas and beans extracts and ovalbumin (pH 5.0) the immunological activity of SE was lost almost completely upon heating. The loss of immunological activity of SEA was accompanied by a concomitant loss of biological activity of this toxin (monkey feeding test). A high pH treatment (pH 11) of the different preparations restored both the immunological and biological activity in most samples tested. Heating at 80 degrees C or 100 degrees C for 10 min of SE containing gelatin (pH 7.0), cauliflower extract (pH 4.0 or pH 7.0), milk (pH 4.0), casein (pH 6.0), rice extract (pH 7.0), noodles extract (pH 4.0) and oat-flakes extract (pH 7.0) had a much lower effect on the immunological activity of the SE (activity greater than or equal to 25%).

Clostridium difficile-associated typhlitis in specific pathogen free guineapigs in the absence of antimicrobial treatment

Clostridium difficile (toxin) associated typhlitis was diagnosed in untreated barrier-maintained specific pathogen free guineapigs. It resembled the pathological lesions of antibiotic induced enterocolitis. The possible role of limited colonization resistance to C. difficile provided by mouse enteric microflora in the pathogenesis of the disease is discussed.

The 'normalization' of germ-free guineapigs with host-specific caecal microflora

Hysterectomy-derived germ-free guineapigs were given colonization-resistant caecal flora from mice (mCRF) or microflora obtained from the caecum of an antibiotic-decontaminated conventional guineapig (gpCRF) and compared with guineapigs raised conventionally with the sow. Body weight and the following intestinal parameters were determined for the groups: colonization resistance (CR) to Escherichia coli, relative caecal weight (RCW), beta-aspartylglycine (faeces), volatile fatty acids (caecum) and bile acids (faeces). mCRF guineapigs showed values quite different from control animals for CR and RCW, indicating the unsuitability of mouse CRF for normalizing guineapigs. In gpCRF guineapigs CR and RCW values were comparable with controls, indicating the suitability of the guineapig flora for normalizing guineapigs. mCRF guineapigs housed with gpCRF guineapigs, showed an improvement in CR and RCW, yielding values found in control animals.

Serological evidence for Encephalitozoon cuniculi infection (nosemiasis) in gnotobiotic guineapigs

Encephalitozoon cuniculi infection (nosemiasis) was serologically diagnosed in hysterectomy-derived gnotobiotically reared guineapigs. The probability of vertical transplacental transmission is discussed.

Otitis media in guinea pigs: pathology and bacteriology

In the course of post-mortem examination of conventional random-bred and inbred (immunosuppressed) strain 2/N guineapigs kept in separate quarters, otitis media was diagnosed in 62 of 462 animals (13.4%) and 18 of 66 animals (27.3%) respectively. Clinical signs of otitis media were seen in only two random-bred animals but in nearly 50% of affected inbred animals. In random-bred guineapigs, purulent, often bilateral, otitis media was associated mainly with the isolation of Streptococcus zooepidemicus, Bordetella bronchiseptica, Pasteurella and Actinobacillus spp. and micrococci. In strain 2/N guineapigs serous or purulent often bilateral otitis media was associated mainly with the isolation of B. bronchiseptica and Pseudomonas aeruginosa serotypes 10 and 11. The simultaneous occurrence of similar pathogenic bacteria in both ears of bilaterally affected animals and in pneumonic lung tissue (in random-bred animals) suggested ascending and descending infection originating from the upper respiratory tract. It is concluded that otitis media, associated with the isolation of a variety of respiratory bacterial species, must be considered a major disease problem in guineapigs.

Isolation of members of the Haemophilus-Pasteurella-Actinobacillus group from feral rodents

46 feral rodents, including a common vole (Microtus arvalis), house mice (Mus musculus), muskrats (ondatra zibetica), house rats (Rattus rattus) and brown rats (R. norvegicus) were examined for bacteria of the Haemophilus-Pasteurella-Actinobacillus group. Haemophilus spp. (only M. musculus examined) were not obtained. All animal species were found contaminated by P. pneumotropica and/or Actinobacillus spp. Almost all M. musculus (96%) and most Rattus spp. (76%) were contaminated by P. pneumotropica and/or Actinobacillus spp. These bacteria were obtained most frequently from the upper respiratory tract, to a lesser extent from the lung and rarely from caecal contents. It is concluded that feral rodents might constitute an important source of contamination of laboratory rodents by members of the HPA-group.

Opportunistic infections in hysterectomy-derived, barrier-maintained guinea pigs

Guineapigs were rederived by hysterectomy and associated with a colonization-resistant enteric microflora (CRF) of mouse origin to establish a strict barrier-maintained breeding colony. Infections were suspected in 55 of 209 animals autopsied. From 65 of 67 tissue samples selected for bacteriological examination 167 isolates, belonging to 16 usually non-pathogenic bacterial species or groups, were isolated mostly from cases of mastitis, typhlitis, enteritis, otitis media and pneumonia. Faecal streptococci, Pseudomonas aeruginosa, Clostridium perfringens, Citrobacter spp., C. freundii, Escherichia coli, Klebsiella oxytoca and Enterobacter cloacae accounted for 86.8% of all isolates. Variations in the recovery rate of these 8 species during the study and a gradual decline in the incidence of infections were observed. Elimination by rederivation of the autochthonous bacterial flora seemed to have predisposed to opportunistic infections by aerobic and facultatively anaerobic bacteria. Enteric colonization resistance to the growth of these bacteria was presumably insufficiently provided by the CRF of mouse origin and might be remedied by using a flora of guineapig origin.

The 'normalization' of germ-free rabbits with host-specific caecal microflora

Hysterectomy-derived germ-free rabbits were given colonization-resistant caecal flora (CRF) from mice, or microflora obtained from the caecum of an antibiotic-decontaminated conventional rabbit and compared with rabbits conventionally raised with the doe. Bodyweight and the following intestinal parameters were determined for the 3 groups: colonization resistance to E. coli, relative caecal weight, villus:crypt ratio (ileum), beta-aspartylglycine (faeces), volatile fatty acids (caecum), and bile acids (faeces). Germ-free rabbits given mouse CRF-flora showed values quite different from control animals for most parameters, indicating unsuitability of mouse CRF flora to 'normalize' rabbits. In germ-free rabbits given modified (antibiotic-treated) rabbit flora, values for most parameters were intermediate between those found for the other 2 groups. This species-specific caecal flora should be improved to provide full 'normalization' of germ-free rabbits.

Influence of housing conditions on pregnancy outcome in cynomolgus monkeys (Macaca fascicularis)

Female cynomolgus monkeys (Macaca fascicularis) were kept under 3 different housing conditions: individually in type A cages (45 X 45 X 60 cm), individually in type B cages (70 X 70 X 100 cm) and as couples in type B cages. Primigravida did not show early embryonic mortality, differing significantly from 11.5% early losses in multigravida. Early embryonic mortality was not affected by housing condition. Further reproductive failure rates did not differ significantly for primigravid (18.5%) and multigravid females (24.0%), though abortion tended to occur more frequently in primigravida. Perinatal mortality (16.1%) accounted for most of the losses under each housing condition. More successful pregnancies (90%) were recorded for females housed individually in type B cages than for females housed in type A cages (68%). About 50% of the couples originally established remained until weaning of their infants, yielding 77% viable offspring. For multigravid females statistical evaluation showed a significant effect of housing conditions on reproductive outcome (X2-test 0.01 less than P less than 0.05) that could be entirely attributed to low losses in females housed individually in type B cages. It is concluded that housing conditions can have a profound influence on reproductive success in cynomolgus monkeys.

Vertical transmission of Bacillus piliformis infection (Tyzzer's disease) in a guinea pig: case report

Tyzzer's disease (Bacillus piliformis infection) was diagnosed at necropsy in a hysterectomy-derived, gnotobiotically reared guinea pig. This is the first description of spontaneous vertical, presumably transplacental, transmission of B. piliformis infection. Subsequent horizontal transmission of the infection was concluded from the presence of specific anti-B. piliformis antibodies in the sera from guinea pigs originating from different litters but reared in the same isolator.

Recovery of members of the Pasteurella-Actinobacillus-group from guinea pigs

In the course of post-mortem bacteriological examination of conventional guinea pigs, 88 isolates belonging to the Pasteurella-Actinobacillus-group were recovered from 69 of 279 animals (25%). Most isolates were recovered from pneumonic lung, enteritic jejunum and inflamed mammary gland. No relationship was found between biotype and source of isolation. About 50% of isolates were recovered in pure culture or as the predominant micro-organism. It is concluded that members of the Pasteurella-Actinobacillus-group must be considered potentially pathogenic for guinea pigs.

Extraction of Staphylococcal Enterotoxins (SE) From Minced Meat and Subsequent Detection of SE with Enzyme-Linked Immunosorbent Assay (ELISA)

ELISA (enzyme-linked immunosorbent assay) was employed to demonstrate staphylococcal enterotoxins A, B, C and E (SEA, SEB, SEC and SEE) in minced meat (50% beef/50% pork). For unheated minced meat, extraction of the sample with an equal amount of distilled water at pH 4.5 and a subsequent concentration (10-fold) of the extract, readjusted to pH 7.2, was sufficient to detect less than 0.5 μg of SE per 100 g of product. The extraction procedure gave 40-80% recovery of the toxin, and using the ELISA system neither false-positive nor false-negative results were obeserved. Using the just mentioned extraction procedure, recovery of SE that had been heated in minced meat was low (0.14% for SEB). It was demonstrated that components extracted by heating (among others, gelatin) present in minced meat caused immunological inactivation of SEB, SEC and SEE during heating. From monkey-feeding tests it became clear that the immunological inactivation of SEB in gelatin by heating was accompanied by biological inactivation.

Skin grafting and graft rejection in goats

As part of a study to define the major histocompatibility complex of the goat and to show certain aspects of its biological function, a skin-grafting technique is described which might also be applicable for similar studies in other ruminant species.