Staphylococcosis of turkeys. 3. Bacterial interference as a possible means of control

Two Staphylococcus epidermidis isolates from turkeys were used as interfering agents to help control staphylococcosis. Both isolates adhered to tissues of the turkeys' respiratory tract, interfered with attachment of virulent S. aureus, produced bacteriocins bacteriocidal to S. aureus, and were avirulent for turkeys. About 200,000 turkeys in commercial flocks were exposed to aerosols of these interfering isolates between 1 and 6 weeks of age, and many became colonized with these bacteria. The aerosol-treated turkeys had lower levels of colonization with S. aureus and had a 3% higher gross survival rate than untreated control turkeys.     

Preliminary studies on bacterial interference of staphylococcosis of chickens

Previous studies indicated that Staphylococcus epidermidis strain 115 might be an effective interfering agent in reducing the rate of staphylococcosis in turkeys. In the present study, strain 115 was avirulent when administered to 3-day-old chicks by oral, aerosol, or intravenous route. Strain 115 adhered specifically to tracheal, lung, air-sac, and liver cells in vitro and interfered with subsequent colonization by virulent Staphylococcus aureus. In vivo colonization of lungs and livers of young chicks occurred following exposure to aerosols of strain 115. Strain 115 interfered with the in vivo colonization of lungs and livers by virulent S. aureus.     

The effect of immunosuppression on protective immunity of turkey poults against infection with turkey coronavirus

The objective of the present study was to evaluate the protective effect of humoral and cellular immunities on turkeys infected with turkey coronavirus (TCV). Two trials were conducted with two separate hatches of turkey poults. Turkey's were experimentally immunosuppressed with cyclosporin A (CsA) or cyclophosphamide (CY) and infected with TCV. Prior to infection, treatment with CsA selectively suppressed T cell activity as revealed by 2-3 fold decreased (p < 0.1) lymphocyte proliferation responses to a T cell mitogen, concanavalin A (Con A). Treatment with CY mainly induced B cell deficiency as indicated by significant reductions (p < 0.05) in antibody responses to sheep erythrocytes 7 days after injection. Body weight gain of turkeys treated with CY was significantly lower (p < 0.05) than that of untreated turkeys at 9 days post-infection (PI). Turkeys treated with CY had 1-2 fold higher immunofluorescent antibody assay (IFA) scores for TCV antigens (p < 0.05) in the intestine than untreated turkeys at 9 or 14 days PI. These results suggested that humoral immunity against TCV infection may be important in turkeys.     

Staphylococcosis of turkeys. 4. Characterization of a bacteriocin produced by an interfering Staphylococcus

A Staphylococcus epidermidis isolate designated strain 115, which is used as an interfering agent against staphylococcosis of turkeys, produces a bacteriocin that was partially purified and characterized in this study. This bacteriocin diffused through agar media, but it was not found in appreciable quantities in the supernatant fluid of broth cultures. Extraction of the bacterial cells with 7 M urea, 1% sodium dodecyl sulfate, or 1% Triton X-100 caused considerable amounts of the bacteriocin to go into solution. This substance was partially purified by selective chemical extraction and by gel filtration chromatography using a Sephacryl S-300 column. This bacteriocin had two active forms: an aggregate, and a small-molecular-weight form estimated by gel filtration chromatography to be less than 6500. Activity was not affected by heat, repeated freeze-thaw cycles, pH 2 and pH 10, or a variety of proteolytic enzymes, nucleases, a lipase, and lysozyme.     

The relationships between vaginal collagen, plasma oestradiol and uterine prolapse in turkeys.

Uterine and vaginal collagen content and plasma oestradiol concentration were measured in traditional, male-line and prolapsed male-line turkeys to investigate the higher incidence of uterine prolapse in the male-line strain. The effect of exogenous oestradiol on vaginal collagen and plasma oestradiol was also tested in the traditional and male-line strains. Vaginal collagen was significantly lower in the male-line compared to the traditional-line, while it was lowest in prolapsed male-line turkeys. Plasma oestradiol concentration was higher in the traditional-line than the male-line. No difference in plasma oestradiol concentration was found between prolapsed and non-prolapsed male-line turkeys. Administration of oestradiol for 7 days significantly raised plasma oestradiol concentration but had no effect on vaginal collagen. Decreased vaginal collagen content was associated with uterine prolapse and may predispose the male-line strain to uterine prolapse. There was no evidence from these results to support an involvement of oestradiol in uterine prolapse in male-line turkeys.     

Safety of Mycoplasma gallisepticum vaccine strain 6/85 after backpassage in turkeys

The objective of this research was to evaluate the safety of the 6/85 strain vaccine strain of Mycoplasma gallisepticum in turkeys by backpassing the vaccine strain up to 10 times by contact infection in turkeys and challenging turkeys with the resulting backpassaged strain. The vaccine strain, however, did not spread to in-contact turkeys, and it was necessary to reisolate the organism before challenging turkeys for the next passage. The challenge strain, therefore, was one that had been backpassaged four times in turkeys, with a total in vivo time in turkeys of 66 days. The backpassaged 6/85 vaccine strain was no different in pathogenicity than the original vaccine strain, except that at 10 days postchallenge, it was isolated in higher numbers from air sacs. Both the original 6/85 vaccine strain and the backpassaged strain were apathogenic in turkeys, except for a slightly increased diameter of the tracheal mucosa at 10 days postchallenge; at 20 days postchallenge the tracheal mucosal thickness was no different from that of controls.     

Experimental infection of turkeys with Mycoplasma gallisepticum of low virulence, transmissibility, and immunogenicity.

Three-week-old turkeys were inoculated intranasally with approximately 10(6) colony-forming units (CFU) of putative variant Mycoplasma gallisepticum (MG) strains M876, M35, or the virulent S6 reference strain. Uninoculated turkeys in each group served as contact sentinels. The hemagglutination-inhibition (HI) test and enzyme-linked immunosorbent assay (ELISA) were used to determine serologic responses. MG was isolated from 100% and 92% of S6- and M876-inoculated turkeys, respectively, on day 7 PI. However, culture-positive rates among M876-inoculated turkeys declined more rapidly, transmission to contact sentinels took longer and occurred at lower rates, and serologic responses measured by HI and ELISA were lower than in S6-infected turkeys. Testing sera from inoculated turkeys for antibodies to MG in homologous and heterologous ELISA systems indicated that strain M876 was significantly (P less than 0.05) less immunogenic than S6 (days 62 and 95 PI), and that the homologous ELISA was more sensitive (P less than 0.005). MG strain M35 failed to infect turkeys in three attempts, even though the inocula used were viable on culture media.     

Poult malabsorption syndrome. III. Skeletal lesions in market-age turkeys.

Skeletal deformities, a major contributing factor to economic losses in market-age turkeys, may be associated with the poult malabsorption syndrome. A study was performed to determine whether the naturally occurring malabsorption syndrome produces skeletal lesions in turkeys at market age. Poults were placed on litter on which poults had previously developed malabsorption. Exposed poults developed enteric disease with 21% mortality during the first 3 weeks. Controls had no enteric disease and no mortality. At the end of the study, 20-week-old exposed turkeys weighed 0.621 kg (5%) less than controls and had a higher incidence of angular limb deformities with significantly higher angulation scores. Exposed turkeys also had a greater incidence of rotated tibias and bowed tibias. The mechanical property of tibial shear strength was significantly lower in turkeys that had survived the earlier poult malabsorption syndrome.     

Staphylococcosis of turkeys. 1. Portal of entry and tissue colonization

Staphylococcus aureus and various coagulase-negative staphylococci were isolated from turkeys with staphylococcosis. Virulent S. aureus adhered well (averaged more than 100 bacteria per tissue cell) in vitro to cells from tissues of the respiratory tract but did not adhere well (averaged fewer than 12 bacteria per tissue cell) to cells from tissues of the alimentary tract. Some avirulent coagulase-negative staphylococci also adhered well to cells from the respiratory tissues. Lungs and livers of turkeys became colonized with virulent S. aureus following experimental aerosol exposure. Tracheas, livers, and hock joints of some market-age turkeys were naturally colonized with S. aureus and various species of coagulase-negative staphylococci.     

Distribution of immunoglobulin-bearing cells in the gut-associated lymphoid tissues of the turkey: effect of antibiotics

Distribution of immunoglobulin (Ig)-bearing cells in the gut-associated lymphoid tissues of antibiotic treated and untreated control turkeys (Meleagris gallopavo) was compared. Antibiotic treatment was similar to a regimen used in commercial turkey production, which included preincubation dipping of fertile eggs in gentamicin solution, injection of turkeys with gentamicin at hatching, and inclusion of chlortetracycline in the diet. Tissues were examined from turkeys at 3, 7, 14, and 21 days of age with a direct immunofluorescence procedure. Cell distribution in control turkeys was as follows: In the bursa of Fabricius, IgA-carrying cells predominated at 3 days of age, but at later intervals, the 3 classes of Ig-bearing cells were in equal numbers. In the cecal tonsils, IgM- and IgA-bearing cells were in larger numbers at 3 days of age, whereas, the IgG-bearing cells were sparsely distributed. By 7 days of age, IgM cells became more numerous in the cecal tonsils and remained numerous until 21 days of age. At 3 days of age, IgA cells predominated in the small intestines and IgM cells predominated in the large intestine. At 7 and 14 days of age, IgM cells were more numerous in the small and large intestines, but by 21 days of age, IgA cell population equaled that of IgM. The IgG cells were generally sparse in the intestines. Antibiotic treatment often resulted in lower numbers of Ig-positive cells, especially those bearing IgM and IgA. Normal development of the bursa of Fabricius was also retarded in this group.     

Effect of cyclophosphamide immunosuppression on the immunity of turkeys to viral rhinotracheitis.

Turkey poults, free of antibodies to turkey rhinotracheitis (TRT) virus were treated with cyclophosphamide on days 1, 2 and 3 after hatching and vaccinated by eyedrop when 10 days old with a Vero cell-attenuated preparation of TRT virus. No ELISA antibodies to TRT virus developed in the sera of these poults but they were as resistant to virulent virus challenge 21 days later as vaccinated groups which were not cyclophosphamide-treated but produced humoral antibodies. Following challenge with virulent virus at 31 days old cyclophosphamide-treated unvaccinated poults developed a more severe clinical response than untreated birds and had higher virus titres in tracheal swabs. The findings show that the respiratory tract of turkeys may be resistant to TRT despite the absence of ELISA antibodies in the serum.     

Use of competitive exclusion to protect newly-hatched chicks against intestinal colonisation and invasion by Salmonella enteritidis PT4.

1. The recommended dose of a commercial competitive exclusion (CE) product (BROILACT) was given orally to newly-hatched broiler chicks to protect them against oral challenge by Salmonella enteritidis PT4. 2. In 5 replicate trials, half of the birds thus treated and half from untreated control groups were examined for salmonellas at 5 d and the other half at 12 d after challenge. 3. Caecal contents were examined quantitatively while heart, liver and spleen samples were examined qualitatively by enrichment. 4. The treatment effectively prevented both colonisation of the caeca and invasion of the other organs by S. enteritidis PT4; the average number of salmonellas was less than 10 colony forming units (cfu)/g of caecal contents in the treated birds and more than 10 million cfu/g in the untreated birds. 5. Infection of organs other than the caeca was completely prevented by protective treatment, whereas 38% of the untreated birds were still infected at the end of the trial.     

Minimization of pathologic changes in Ornithobacterium rhinotracheale infection in turkeys by temperature-sensitive mutant strain

The protection elicited by a temperature-sensitive (Ts) mutant of Ornithobacterium rhinotracheale (ORT) vaccine against challenge with pathogenic strain was investigated. In Experiment 1, specific serologic response to ORT was detected in 12%-19% of Ts-vaccinated birds at 3 wk postvaccination by either drinking water or oculo-nasal instillation. At 7 days postchallenge, 100% of Ts-vaccinated turkeys of all groups were able to respond with an ORT-specific antibody response, but the control group was not, suggesting the potential of Ts strain to evoke immune protection. The study also revealed a statistically significant ability of the Ts strain to protect vaccinated turkeys against gross lesions caused by the pathogenic strain of ORT in treated groups vs. control. In Experiment 2, seroconversion was detected by enzyme-linked immunosorbent assay in birds after they were given the Ts strain in drinking water in field conditions. The results of the field study showed mean scores of gross lesions of nonvaccinated/challenged groups to be up to seven times higher than those of the vaccinated/challenged group. In addition, reisolation rates and quantification of ORT colonies per gram of lung tissue were significantly lower for vaccinated/challenged than for nonvaccinated/challenged turkeys. In conclusion, results from laboratory and field experiments suggest that use of the Ts mutant strain of ORT as a live vaccine would be a suitable method to evoke protection against ORT infection in turkeys.     

Studies on Pasteurella multocida. IV. Immunofluorescence detection of the organisms in spleen and lungs of turkeys vaccinated with live oral vaccines

Oral vaccination of turkeys with live avirulent strains of P. multocida (M-2283 and CU strain) resulted in the local as well as systemic dissemination of the organisms. The persistence of P. multocida in the lungs and splenic tissues of these vaccinated turkeys was demonstrated by the indirect immunofluorescence technique. All of the tissues examined up to the first week post vaccination were P. multocida positive. Cryostat sections of lungs from birds vaccinated with the avirulent strain M-2283 were negative at 2 weeks post vaccination, while the spleen continued to be positive up to the third week post vaccination. In contrast to the group of turkeys vaccinated with strain M-2283, lung and spleen cryostat sections from turkeys vaccinated with strain CU remained positive up to the fourth week post vaccination. Tissues examined thereafter were negative for the presence of P. multocida from both groups.The major immune mechanism in the defense against fowl cholera is still unknown. If local immunity is primarily responsible, the CU strain may be the better vaccine strain as it persists in the lungs for 2 weeks longer than the M-2283 strain. However, if systemic immunity is chiefly responsible for immunity, both strains could protect equally, since they persist in the spleen for approximately the same period of time.     

A descriptive study of fowl cholera in California meat turkeys: August 1985-July 1986

One hundred sixty meat-turkey premises in California were monitored for outbreaks of fowl cholera from August 1985 through July 1986. Nearly 27 million turkeys in 720 flocks were at risk during the year. Fifty-three flocks of approximately 3 million turkeys on 34 different premises experienced confirmed fowl cholera outbreaks. The epidemic curve for the year indicated that the majority of outbreaks occurred in the late summer and fall, particularly in October. The incidence of outbreaks during this time was not significantly associated with seasonal variation in the size of the turkey population. The mean flock age at outbreak was 10.8 weeks, with a range of 5-18 weeks.     

Clinical experience with deslorelin (ovuplantTM) in a kentucky thoroughbred broodmare practice (1999)

Palpation records of 155 Throughbred broodmares maintained on one of seven farms (3–80 mares per farm) that were administered deslorelin on one or more estrous cycles (204 treated cycles) during the 1999 breeding season were retrospectively examined. Some deslorelin-treated mares were also treated with hCG (2500 units intravenously), or had no ovulation-inducing drugs administered, during different estrous cycles of the same season. Most mares were treated with an ovulation- inducing drug after returning to their resident farm following breeding and were subsequently examined by transrectal ultrasonography daily until ovulation was confirmed, and again 13–14 and 15–16 days after ovulation for determination of pregnancy status.Per-cycle pregnancy rate for all 155 mares bred was 53%, and for all deslorelin breeding was 57%. Per-cycle pregnancy rates for mares ovulating 0–1 days, 1–2 days, and 2–3 days after treatment with deslorelin did not differ (P>0.05). Forty-six mares received more than one treatment during the breeding season, yielding 115 breedings (estrous cycles) for comparison of pregnancy rates among treatment. Per-cycle pregnancy rates for these mares did not differ among treatments (P>0.10).No differences due to treatment were detected in mean interval to ovulation (P>0.10). Mean interovulatory interval was longer for deslorelin-treated mares than for untreated or hCG treated mares (P>0.01). Eighty percent (80%) of deslorelin-treated mares had interovulatory intervals of 18–25 days, and 19% had interovulatory intervals>25 days. Ninety-seven percent (97%) of untreated or hCG-treated mares had interovulatory interovulatory intervals>25 days. More deslorelin-treated mares had extended (>25 days) interovulatory intervals than hCG- or nontreated-mares (P>0.05). In this group of Thoroughbred mares, it appeared that season (month) and management (farm) factors had only minor effects on the incidence of extended interovulatory intervals following use of deslorelin.     

Attenuated live fowl cholera vaccine. I. Development of vaccine strain M3G of Pasteurella multocida

A live cholera vaccine was developed from a virulent avian septicemia strain of Pasteurella multocida serotype 1. The virulent parental strain was mutagenized with N-methyl-N'-nitro-N-nitroso guanidine. Mutants were selected that had either smaller colonies at 37 C or temperature sensitivity for growth at 41 C. Four small-colony mutants and 2 temperature-sensitive mutants were studied. All the mutants were avirulent for turkeys. Sixteen days after turkeys were vaccinated with each mutant, both the vaccinates and unvaccinated controls were challenge-exposed to virulent P. multocida of the homologous serotype and the heterologous serotype 3. Two of the small-colony mutant strains protected against both homologous and heterologous challenge. Suggested for a live cholera vaccine is P. multocida M3G, a small-colony-forming mutant, innocuous for both mice and turkeys and stable against reversion.     

Effects of bursectomy, irradiation, and cyclophosphamide on turkeys vaccinated with CU cholera strain

Turkeys surgically bursectomized, irradiated, and/or injected with cyclophosphamide at 1 day were vaccinated with the live Clemson University (CU) strain of Pasteurella multocida. Bursectomized turkeys vaccinated via drinking water or wing-web puncture at 7 weeks and challenged at 11 weeks had a significantly (P less than 0.05) lower survival rate after challenge than unbursectomized controls. Bursectomized and unbursectomized turkeys vaccinated via drinking water at 7 weeks, revaccinated via the auditory tube at 11 weeks, and challenged at 15 weeks had similar survival rates. The vaccinated bursectomized turkeys had significantly (P less than 0.05) lower levels of serum anti-P. multocida antibody than vaccinated unbursectomized controls. Radiation had no immunosuppressive effect. The immunosuppressive effect of cyclophosphamide was dosage-dependent. Bursectomy and injection of cyclophosphamide in the same turkey were complementary. It was concluded that in young turkeys, the development of immunity to the avirulent CU vaccine is highly dependent upon the bursa of Fabricius, but that as they grow older the bursa is of less importance, particularly if they were vaccinated via a parenteral route, such as in the air spaces of the head.     

Colonization of rabbits with Staphylococcus aureus in flocks with and without chronic staphylococcosis.

Rabbits of 19 rabbitries were examined for the presence of Staphylococcus aureus in nine different body sites. Seven rabbitries experienced epidemically spreading signs of staphylococcosis while the other 12 rabbitries did not. S. aureus was isolated in all seven flocks that suffered from chronic problems of staphylococcosis and in 11 of the 12 clinically healthy flocks. The mean percentage of infected animals in these two groups was 90 and 43.3%, respectively. S. aureus was isolated from all body sites examined, but the ear and the perineum were often more intensely colonized. The number of animals colonized with S. aureus and the mean number of positive body sites in S. aureus positive rabbits were significantly higher in rabbitries with chronic staphylococcosis. This indicates that colonization capacity of S. aureus plays a role in epidemically spreading disease in rabbits. S. aureus isolates belonged to five different biotypes and 23 different phage types. Several different types simultaneously circulated in contaminated rabbitries and even simultaneously infected individual rabbits. Strains that belonged to the biotype-phage type combination mixed CV-C, 3A/3C/55/71 only occurred in rabbitries chronically dealing with signs of staphylococcosis. This may indicate a relationship between phenotypic strain properties and virulence of S. aureus.     

Endotoxin lipopolysaccharide from Escherichia coli and its effects on the phagocytic function of systemic and pulmonary macrophages in turkeys.

The effect of Escherichia coli lipopolysaccharide (LPS) on the competence of pulmonary macrophages and phagocytic cells from the systemic circulation of turkeys was examined using luminol-enhanced zymosan-stimulated chemiluminescence. The results showed a rapid and accelerated oxidative burst in both systemic and pulmonary macrophages in LPS-treated turkeys that was significantly greater than in untreated controls. However, this increased oxidative metabolism induced by LPS was not associated with enhanced intracellular bacterial killing by pulmonary macrophages. Turkeys treated with LPS showed a highly significant decrease in pulmonary bactericidal activity against Staphylococcus aureus challenge, indicating a defect in pulmonary macrophage function induced by LPS.