Showing papers by "Robert Higgins published in 1993"

Use of polyvalent coagglutination reagents for serotyping of Streptococcus suis.

Abstract: Polyvalent coagglutination reagents (PRs) have been evaluated for the serotyping of Streptococcus suis. Monovalent antisera produced against 28 S. suis reference strains have been grouped to obtain five different pools. A total of 249 field isolates previously identified and belonging to different serotypes were tested with PRs prepared by two different procedures: (i) monovalent coagglutination reagents were individually prepared and mixed in equal proportions, and (ii) antisera were mixed in equal proportions before the addition of the Staphylococcus aureus suspension. Only antisera tested by a tube agglutination test with 2-mercaptoethanol and presenting titers of 1:32 or higher were used. Results obtained with PRs prepared by both procedures were similar, and there was a very good correlation between the capsular type of the isolate and the reaction obtained with PRs. Thus, from a practical viewpoint, it is suggested that PRs be prepared by the first procedure. To isolates, were tested in parallel with both the PRs and the monovalent coagglutination reagents over a 1-year period. Ninety-nine percent of the typeable and all of the untypeable isolates were correctly identified. Serotyping with PRs is suggested to be a very useful and reliable screening procedure, particularly when a large number of S. suis isolates have to be serotyped. In addition, the choice of antisera to be included in a given pool is facultative and should be oriented to the needs of a region or a country.

Detection of immunoglobulin-G-binding proteins in Streptococcus suis

Abstract: SUMMARY: This study was undertaken to search for the presence of immunoglobulin G (IgG)-binding proteins in Streptococcus suis, an important swine pathogen. Whole bacterial cells were incubated with human or pig IgG conjugated to gold particles and examined by transmission electron microscopy. Cells of some S. suis strains were labelled as were cells of the positive control strain, Staphylococcus aureus Cowan I. Binding of pig and human IgG to five different bacterial species of group D streptococci, to reference strains representing the 29 capsular types of S. suis, and to 12 S. suis capsular type 2 strains was then examined using Western blotting. All strains interacted with pig and human IgG, although the binding profiles were slightly different. A 52 kDa protein was observed in all capsular types of S. suis. This protein, absent in other group D streptococcal species, was observed in all capsular type 2 isolates originating from diseased or clinically healthy pigs, and was shown to bind human IgG-Fc fragments. The IgG-binding activity was also observed in the culture supernatant and was sensitive to proteolysis.

Production of capsular material by Streptococcus suis serotype 2 under different growth conditions.

Abstract: The procedure currently used for the production of Streptococcus suis antigen is very long and includes several subcultures. The aim of the present work was to study the in vitro production of capsular material by S. suis serotype 2 after each of these subcultures. The amount of capsular material produced was evaluated by electron microscopy using bacterial cells grown on blood-agar plates and in Todd-Hewitt broth (THB) or THB supplemented with serum. In addition, the production of antibodies in rabbits with antigens produced using different growth conditions was compared. Antigens produced after only three subcultures possessed as much capsular material as cells obtained after the complete procedure and induced a similar antibody response. The use of serum as a supplement to the broth did not assure a higher production of capsule; in addition, antibody titers obtained with antigens produced in THB were as high as those obtained with antigens produced in THB supplemented with serum. We recommend the use of three subcultures in nonsupplemented broth for the production of immunogens. This revised protocol offers two main advantages: it is less time-consuming because of the limited number of subcultures and is also less expensive since nonsupplemented broths are used.

The effectiveness of gentamicin or polymyxin B for the control of bacterial growth in equine semen stored at 20 degrees C or 5 degrees C for up to forty-eight hours.

Abstract: Semen from three stallions was used to evaluate the effectiveness of two antibiotics added to semen extender for samples stored at 20 degrees C or 5 degrees C for up to 48 hours Each ejaculate was divided into six different treatments: semen+extender (SE); SE+gentamicin (100 micrograms/mL); SE+polymyxin B (1000 units/mL); and each of the above treatments inoculated with Pseudomonas aeruginosa ATCC 27853 Sampling of diluted semen for bacteriological analysis was performed after 2, 8, 24 and 48 hours of preservation at either temperatures The presence of nonspecific bacteria was noted after two hours in all SE aliquots The number of bacteria did not change in samples stored at 5 degrees C, while in samples preserved at 20 degrees C, it increased by three to four times after 48 hours In semen aliquots treated with either of the antibiotics, the number of nonspecific bacteria was very low after two and eight hours at both temperatures This number remained stable up to 48 hours at 5 degrees C, while an increase was noted at 24 and 48 hours at 20 degrees C At 5 degrees C, the number of P aeruginosa cells tended to decrease between 24 and 48 hours in SE aliquots The presence of gentamicin or polymyxin B appeared to rapidly inhibit growth of P aeruginosa At 20 degrees C, growth of P aeruginosa increased between 8 and 24 hours in SE, while the presence of antibiotics almost completely inhibited the growth of the bacterium(ABSTRACT TRUNCATED AT 250 WORDS)

A sandwich enzyme-linked immunosorbent assay for the detection of Streptococcus suis.

Abstract: A double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) was developed for the detection and the identification of Streptococcus suis capsular types 1, 2, 1/2, 3 and 22. The specificity of this test was first evaluated using reference strains of S. suis capsular types 1 to 28 and 1/2 as well as 15 different bacterial species susceptible to be isolated from swine. The ELISA developed was very specific for capsular types 1, 3 and 22 but it could not discriminate between capsular types 2 and 1/2. In a second study, S. suis isolates from 328, 493, 368 and 76 diseased pigs were used to detect capsular types 1, 2 or 1/2, 3 and 22 respectively. The relative specificity and sensitivity varied between 98% and 100%. The ELISA results were in excellent agreement with the standard techniques (biochemical tests, coagglutination and capsular reaction tests) in detecting both positive and negative strains. Kappa values were 0.80, 0.99, 0.97 and 1.00 for detecting S. suis capsular types 1, 2 or 1/2, 3, and 22 respectively. To evaluate the relative-sensitivity of the test, primary cultures from 73 diseased pigs and tissue samples from 67 diseased pigs were used directly for detecting these capsular types. With primary cultures, the relative specificity and sensitivity (95.9% and 91.6% respectively) remained high and the test was very suitable (Kappa = 0.87). The ELISA using tissue samples gave a good specificity (97.6%), a moderate sensitivity (62.5%) and a low agreement with standard tests (Kappa = 0.64).(ABSTRACT TRUNCATED AT 250 WORDS)

Septicemic Enterococcus infection in an adult llama.

Abstract: >> the meningoencephalitic form of the disease. 2,11 Listeria1 abortion is relatively common in sheep, cattle, and goats, is rare in other species, 1 and has not been reported previously in llamas. In sheep and cattle, there is often clinical illness with fever of up to 40.5 C in the dam, but meningoencephalitis does not usually occur concomitantly with abortion. Abortion usually occurs during the latter stages of gestation, as in this case. Ingestion is considered the most common route of infection leading to abortion. 3 Listeria monocytogenes is ubiquitous in nature and in human and animal feces, so llamas will almost certainly be exposed to the organism. Infection has been repeatedly associated with spoiled silage with a pH >5.0-5.5 1,3 and with various circumstances that might lower the animal’s resistance, including pregnancy. 3 Eperythrozoonosis has also been associated with conditions causing immune suppression 5,9

A Sandwich Enzyme-linked Immunosorbent Assayforthe Detection ofStreptococcus suis

Abstract: A double-antibody sandwich enzyme-linkedimmunosorbent assay(ELISA)wasdeveloped for thedetection andtheidentification of Streptococcus suiscapsular types1,2,1/2, 3and22.Thespecificity ofthis test wasfirst evaluated usingreference strains ofS.suis capsular types1to28and1/2as wellas15different bacterial species susceptible tobe isolated from swine. TheELISAdeveloped was veryspecific forcapsular types1,3 and22butitcouldnotdiscriminate between capsular types 2and1/2. Inasecondstudy, S.suisisolates from328,493,368and76diseased pigswereusedtodetect capsular types1,2or1/2, 3and22respectively. Therelative specificity and sensitivity varied between 98% and 100%.TheELISAresults werein excellent agreement withthestandardtechniques (biochemical tests, coagglutination andcapsular reactiontests) indetecting bothpositive andnegative strains. Kappavalues were0.80, 0.99, 0.97and1.00for detecting S.suiscapsular types1,2 or1/2, 3,and22respectively. To evaluate therelative-sensitivity of