Comparison of culture, PCR, and different serologic tests for detection of Mycoplasma gallisepticum and Mycoplasma synoviae infections.

In this study, the technical performance of culture, two commercially available polymerase chain reaction (PCR) tests, rapid plate agglutination (RPA) test, hemagglutination inhibition (HI) test, and eight commercially available enzyme-linked immunosorbent assays (ELISAs) were compared for the detection of avian mycoplasma infections from 3 days postinfection (d.p.i.) through 35 d.p.i. The tests were carried out on samples from specified pathogen-free layers that were infected at 66 wk of age with recent Mycoplasma synoviae (MS) and Mycoplasma gallisepticum (MG) field strains, MS and MG ATCC strains, and Mycoplasma imitans (MIM), respectively. Results showed a high percentage of positive samples in the homologous infected groups and a high percentage of negative samples (100%) in the uninfected and heterologous infected groups during 35 d.p.i. of both culture and PCR tests. For the group infected with the MG 15302 ATCC strain, serology was more sensitive than bacteriology. All MG and MS tests, with the exception of MG ELISA kit D showed a lower percentage of positive samples during 35 d.p.i. for the detection of the MG and MS ATCC strain infection compared with that of the field strains. Also, the number of cross-reactions (false positives) in the serologic tests was lower after infection with an ATCC strain than after an infection with the MG or MS field strain. Contradictory to other studies, the ELISAs and the RPA test using undiluted serum showed a relatively high number of false-positive results. The MG ELISAs (except ELISA kit D) showed more false-positive results (up to 37%) in the MIM-infected group than in the MS-infected groups. This was not unexpected, as MIM and MG have a close antigenic relationship. The results of the serologic tests in this study showed that a certain level of false-positive results can be expected in about any serologic test. Although the level of false-positive results varied between several serologic tests, this study showed that it is not advisable to rely completely on one test (system) only.

Vaccination against Salmonella enteritidis in Dutch commercial layer flocks with a vaccine based on a live Salmonella gallinarum 9R strain: evaluation of efficacy, safety, and performance of serologic Salmonella tests.

This study describes a field trial in which 80 commercial layer flocks, with an increased risk of Salmonella enteritidis (SE) infection and placed on farms with a certified Standardized Biosecurity Programme (SBP) or a request for a SBP certificate, were vaccinated with a vaccine based on a live attenuated Salmonella gallinarum (SG) 9R strain. An evaluation is presented of the efficacy of the vaccine against SE infections, the effect on the performance of serologic Salmonella tests, and the spread of the vaccine strain to the egg content. For the efficacy study, assessment of the flock level occurrence of SE infections in the vaccinated group of 80 flocks was compared with that of a nonvaccinated group of 1854 flocks hatched in the same period. This control group was examined according to the compulsory control programme in The Netherlands. An evaluation was done of the performance of serologic Salmonella tests and the spread of the vaccine strain to the inner egg content of five of the vaccinated flocks. Findings demonstrated the flock level occurrence of SE infections in the vaccinated group (2/80 = 2.5%) to be significantly (P = 0.01) lower than that of the nonvaccinated group (214/1854 = 11.5%). Vaccination resulted in 59.0% positive test results in lipopolysaccharide BD enzyme-linked immunosorbent assay (ELISA) for detecting antibodies against Salmonella serogroups B and D and 0% positive test results in the rapid plate agglutination test for detecting antibodies against S. pullorum (SP)/SG. The mean specificities of two blocking ELISAs (gm- and i-double antibody sandwich ELISAs) based on the flagellar antigen of SE and Salmonella typhimurium (ST) on the same sera were 99.6% and 96.1%, respectively. The vaccine strain could not be isolated from any of the 450 pools of 10 eggs. On the basis of these results, we concluded that vaccination with a vaccine based on an attenuated SG 9R strain contributes to the reduction of SE infections in commercial layer flocks. Furthermore, serologic monitoring of SE, ST, and SP/SG can still be carried out on flocks vaccinated with an attenuated SG 9R strain. Additionally, we found no indication of the spread of the vaccine strain to the egg content.

The spread of Salmonella gallinarum 9R vaccine strain under field conditions.

A live vaccine based on an attenuated Salmonella gallinarum 9R strain is in use in a Salmonella enteritidis control program in commercial layer flocks in The Netherlands. In a field study, the potential spread of the vaccine strain from vaccinated flocks to nonvaccinated flocks has been studied after both the primary and the booster injection at four different rearing farms and at one layer farm. The vaccinated and the nonvaccinated flocks were monitored at regular intervals by bacteriologic and serologic examination. In this field study, no evidence was found for the fecal spread of the vaccine strain.

[In vitro activity of 12 antibiotics used in veterinary medicine against Mannheimia haemolytica and Pasteurella multocida isolated from calves in the Netherlands]. / In vitro-activiteit van 12 veterinair gebruikte antibacteriële middelen tegen Mannheimia haemolytica en Pasteurella multocida geïsoleerd uit kalveren in Nederland.

Results of susceptibility tests of clinical isolates of animal pathogens are periodically summarized and reported by the Animal Health Service. However, these results are based upon qualitative test methods. In the present paper results of quantitative susceptibility tests of twelve antibacterial agents against Mannheimia haemolytica (MHA) and Pasteurella multocida (PMU) isolated from Dutch calves in 1996 and 1997 are presented. Minimum inhibitory concentrations of amoxicillin, ceftiofur, tetracycline, trimethoprim-sulphamethoxazole, tilmicosin, neomycin, gentamicin, spectinomycin, flumequine, enrofloxacin, chloramphenicol and florfenicol were determined. No resistance was detected for ceftiofur and florfenicol. Three strains had an intermediate susceptibility to tilmicosin. The resistance percentages of MHA and PMU for neomycin, gentamicin, spectinomycin, flumequine, enrofloxacin, and chloramphenicol varied from 2% to 16%. Higher resistance percentages (16%-53%) were observed for amoxicillin, tetracycline, and trimethoprim-sulphamethoxazole. The MIC breakpoints used to determine whether a strain is susceptible, intermediate, or resistant are arbitrary and discussed in this paper.

Use of composite milk samples for diagnosis of Staphylococcus aureus mastitis in dairy cattle.

OBJECTIVE: To measure relative sensitivity and relative specificity for use of composite milk samples, compared with that of individual gland milk samples, for diagnosis of Staphylococcus aureus mastitis. ANIMALS: 505 cows suspected of having subclinical mastitis. Of these cows, 172 were considered infected with Sta aureus, based on the results from individual gland samples. PROCEDURE: Composite and individual gland milk samples were collected from cows suspected of having subclinical mastitis, and results of bacteriologic culturing of samples from the same cow were compared. Results were interpreted at the cow level. Relative sensitivity and relative specificity for composite samples were computed from 2 x 2 tables, using results from individual gland samples as references. RESULTS: Relative sensitivity for use of composite milk samples in diagnosing Sta aureus mastitis was 0.63. The relative specificity was 0.98. Factors influencing the relative sensitivity for composite samples were the number of infected glands per cow, the amount of Sta aureus shedding from infected glands, and the proportion of the composite milk obtained from each gland. CLINICAL IMPLICATIONS: Collecting composite instead of individual gland milk samples increases the number of false-negative results in diagnosing Sta aureus mastitis. By collecting consecutive samples from the same cow or by increasing the inoculum volume at culturing, this problem can be diminished.

[Reliability of bacteriological studies of composite samples in the diagnosis of subclinical udder infections in cattle]. / De betrouwbaarheid van het bacteriologisch onderzoek van mengmonsters voor de diagnose van subklinische uierinfecties bij rundvee.

This study evaluated the reliability of making bacteriological cultures of composite milk samples for the diagnosis of subclinical udder infections in dairy herds. Quarter samples as well as composite samples were collected from 482 cows with suspected subclinical mastitis from 69 Dutch dairy farms. The samples were used to measured somatic cell counts and to prepare bacteriological cultures. The sensitivity and specificity of the bacteriological cultures of the composite samples were compared with those of the quarter samples. The sensitivity of Staphylococcus aureus, Streptococcus uberis, Streptococcus agalactiae and Streptococcus dysgalactiae was 57.9%, 65.2%, 86.6%, and 60.3%, respectively. The specificity was higher than 98% for all four bacteria. Although information is lost when composite samples are used, composite samples are useful, especially for large dairy herds. The advantage and disadvantages of the use of composite samples are discussed.

Comparison between the minimal inhibitory concentration of tilmicosin and oxytetracycline for bovine pneumonic Pasteurella haemolytica isolates.

The minimal inhibitory concentration (MIC) of tilmicosin and oxytetracycline was determined for Pasteurella haemolytica isolated from Dutch cattle in 1991. The agar dilution method was used. Of the Pasteurella haemolytica strains examined, 96% (24) had a MIC for tilmicosin of 2 micrograms/ml or lower; in one strain the MIC was 8 micrograms/ml. The MIC for oxytetracycline was equal to or higher than 64 micrograms/ml in 19 strains (76%), whereas for 5 strains the MIC was 1 microgram/ml and for 1 strain 2 micrograms/ml.

[Pasteurella anatipestifer: a controllable farm problem]. / Pasteurella anatipestifer: een beheersbaar bedrijfsprobleem.

The performance of 13 flocks of ducks on a duck farm decreased markedly. Post-mortem and bacteriological examinations indicated that Pasteurella anatipestifer was a major cause, although Salmonella spp., Escherichia coli and Treponema spp. were also detected. Use of an autovaccine against Pasteurella anatipestifer markedly reduced the signs and symptoms in the second part of fattening period.

[Consequences of a Salmonella typhimurium infection on a veal calf farm]. / Een infectie met Salmonella typhimurium op een vleeskalverbedrijf met gevolgen.

An outbreak of Salmonella typhimurium in veal calves is described. The pattern of resistance to antibiotics was unique in the Netherlands at the time of the outbreak. Other factors besides antibiotic resistance also played a role in the outbreak, resulting in a mortality exceeding 90%.

Radiographic and radionuclide lung perfusion imaging in healthy calves and calves naturally infected with bovine respiratory syncytial virus.

Nine calves between three and 18 weeks old with serologically confirmed natural bovine respiratory syncytial virus infection were examined clinically, radiographically and by radionuclide lung perfusion imaging. The results were compared with those from seven healthy calves. The diseased calves were euthanased and examined pathologically, virologically and bacteriologically. The clinical signs indicated that the disease was in an acute stage. Radiography of the diseased animals revealed cysts, corresponding morphologically with bullous emphysema, and infiltrations roughly corresponding in distribution with atelectatic and, or, pneumonic areas. Radionuclide lung perfusion imaging revealed no perfusion shifts between the left and right lungs and a normal perfusion pattern in five of the nine diseased calves. The abnormalities in the perfusion patterns of three calves were probably caused by anatomical disorders such as cysts and pleural adhesions, but no cause of the abnormality could be found in one calf. These findings suggest that in calves infected with bovine respiratory syncytial virus, the normal perfusion pattern is maintained until anatomical disorders occur. The pathological examination and radiography revealed that the cranioventral lung fields were particularly poorly ventilated. This finding and the normal perfusion pattern indicate that these parts of the lungs are probably the sites where shuntings and perfusion-ventilation mismatchings occur.

[Candida albicans infection in Japanese nightingales: diagnosis therapy and supplementary measures]. / Infectie met Candida albicans bij Japanse nachtegalen: diagnose, therapie en aanvullende maatregelen.

Yeast and fungal infections may constitute a major problem in aviary birds. A case of yeast infection is reported, which was possibly due to antibiotherapy and malnutrition. Ketoconazole is effective in controlling this type of infection. Methods by which these infections may be prevented are recommended, as well as examinations which are useful in aviary birds.

[Leptospirosis in swine; observations on the serological diagnosis of Leptospira interrogans serotype bratislava]. / Leptospirose bij het varken; kanttekeningen bij de serologische diagnostiek van Leptospira interrogans serotype bratislava.

Leptospirosis is considered to be an important cause of porcine reproductive failure. In this respect recently attention is paid to the possible role of Leptospira interrogans serotype bratislava (bratislava). In the present paper the results of serotype bratislava serology conducted on three farms are presented and discussed. On two of the farms no reproductive failure was observed. On the third farm with a high percentage of return to service a longitudinal search was done. No relation could be demonstrated between bratislava titers and reproductive failure.

The influence of the injection site on the bioavailability of ampicillin and amoxycillin in beagles.

Influence of the injection site on bioavailability in dogs was investigated for injections with ampicillin anhydrate or amoxycillin trihydrate suspensions. Firstly, pharmacokinetic parameters were calculated after IV administration of the sodium salts. Then the dogs were injected in the neck (SC), in the lateral thorax region (SC), in the back (IM) and in the thigh (IM), respectively. The most obvious depot effect was seen after subcutaneous injection of ampicillin in the thorax region, though bioavailability seemed to be low. No differences were seen between the injection sites with amoxycillin. For ampicillin SC injection in the neck seems most favourable; for amoxycillin SC injection may be preferred because it is less burdening. Serum concentrations with amoxycillin were higher and persisted longer than with ampicillin. Further investigation is necessary to determine whether this also counts for tissues or focus of infection.

Clinical Leptospira interrogans serogroup Australis serovar lora infection in a stud farm in The Netherlands.

A Leptospira interrogans serogroup australis serovar lora infection in a stud farm is reported. During three successive years (1984-1986) clinical leptospirosis with a severe often rapid, fatal course was seen in 12 foals. Clinical examination revealed severe respiratory distress, depression and pyrexia. Other symptoms were diarrhea (2), jaundice (1), and an unsteady gait (1). Morphological characteristics of the disease were massive pulmonary haemorrhage and haemorrhagic-thrombotic or extracapillary glomerulonephritis with tubulonephrosis and interstitial oedema. In most foals high or increasing MAT titres to serovar bratislava were found; from one foal Leptospira interrogans serovar lora was isolated. Serological examination of all 56 mares at the farm (August 1986) revealed antibodies to serovar bratislava in 64 per cent of the animals. These findings support the idea that Leptospira interrogans serovar bratislava and closely related strains (in this study serovar lora) may be adapted to and maintained by the horse population.

[Leptospirosis in cattle; milker's fever in cattle farmers]. / Leptospirose bij runderen; melkerskoorts bij de veehouders.

In this paper the symptomatology, epidemiology, and diagnosis of Leptospira interrogans serovar hardjo infections in cattle are reviewed. The possibilities on monitoring and control of this disease in both foreign countries and the Netherlands are discussed. Special attention is paid to the zoonotic aspects of the infection (dairy fever).

[Mycoplasma bovis arthritis in a herd of dairy cattle]. / Mycoplasma bovis arthritis in een koppel melkvee.

Cases of severe arthritis due to M. bovis in a herd of dairy cattle are reported. M. bovis was also isolated from the mammary tissues and lungs of one of the lame animals at autopsy; this animal did not show any symptoms of respiratory disease or mastitis. M. bovis was detected in milk samples of eight animals in which mastitis was present or absent, though not in any of the animals affected with arthritis. Antibiotic therapy failed to produce permanent results in the lame animals. Ultimately, spontaneous recovery occurred in these cases. M. bovis was no longer isolated following the short period during which lameness was present.