Prevalence, serotype, and antimicrobial resistance of Salmonella on broiler carcasses postpick and postchill in 20 U.S. processing plants.

The objective of this study was to measure the effect of broiler processing on the prevalence, serotype, and antimicrobial resistance profiles of salmonellae. Twenty U.S. commercial processing plants representing eight integrators in 13 states were included in the survey. In each of four replications, 10 carcasses from one flock were collected at rehang and 10 more carcasses were collected at postchill; each carcass was sampled by whole-carcass rinse. Salmonella organisms were isolated from carcass rinses by standard cultural techniques, serotypes were determined, and the resistance to 15 antimicrobials was measured. Overall, Salmonella was detected on 72% of carcasses at rehang (ranging from 35 to 97%) and on 20% of carcasses postchill (ranging from 2.5 to 60%). In every instance, a significant (P < 0.05) decrease in Salmonella prevalence was noted between rehang and postchill. The four most common serotypes, accounting for 64% of all Salmonella isolates, were Kentucky, Heidelberg, Typhimurium, and Typhimurium var. 5-; most isolates of Kentucky (52%), Heidelberg (79%), and Typhimurium (54%) serotypes were susceptible to all antimicrobial drugs tested. However, only 15% of the Typhimurium var. 5- isolates were pansusceptible; more than one-half of the isolates of this serotype were resistant to three or more drugs. No isolate of any serotype exhibited resistance to amikacin, ceftriaxone, ciprofloxacin, or trimethoprim-sulfamethoxazole. These data demonstrate that although processing lessens carcass contamination with Salmonella, antimicrobial-resistant isolates may still be present.

In vitro evaluation of B-lymphocyte function in turkeys infected with hemorrhagic enteritis virus.

Studies were conducted on B-lymphocyte function in turkeys infected with hemorrhagic enteritis (HE) virus. Hemolytic plaque-forming technique was used to detect antibody-forming cells in turkeys. The plaque-forming cell responses in HE virus-infected and noninfected controls were compared. Results of this study indicated a decreased capability of HE virus-infected turkeys to produce antibodies to sheep RBC. The greatest inhibition of antibody-forming cell production was seen in the turkeys 19 days after exposure to the virus. However, after this period, the turkeys gradually recovered their immunocompetence to sheep RBC.

In vitro depression of the mitogenic response of lymphocytes from turkeys infected with hemorrhagic enteritis virus.

A depression in the mitogenic response of lymphocytes was demonstrated in turkeys inoculated with hemorrhagic enteritis virus. Blood samples were collected (in heparin) once a week, beginning 1 week after the turkeys were inoculated. The whole blood assay was used to study lymphoblastogenesis. Concanavalin-A and phytohemagglutinin were the mitogens used: the radioisotope used was (125I)deoxyuridine (125IudR; 125I, sp act 5 Ci/mg). Suppression in the lymphocyte response in vitro was seen up to 5 weeks after the inoculations were done, after which there was a gradual recovery from suppression in the lymphocyte blastogenesis.

Detection of turkey coronaviral enteritis (bluecomb) in field epiornithics, using the direct and indirect fluorescent antibody tests.

In Minnesota, efforts have been made over the past 10 years to eliminate turkey coronaviral enteritis (TCE, bluecomb) by controlled depopulation and decontamination with a rest period before restocking. In 1973, clinical observations indicated that bluecomb was restricted to one limited area in Minnesota. Five epiornithics occurred during late 1973 and 1974, involving 5 different farms in this limited geographic area. During 1975, 3 epiornithics of TCE were investigated, involving 185,000 turkeys in 17 flocks, of which approximately 17,000 died. Naturally infected turkeys representing 7 operations between 1973 and 1976 were examined by both the direct fluorescent antibody test and indirect fluorescent antibody test (IFAT). The direct fluorescent antibody test detected coronaviral antigen in intestinal tissues during the acute phase of the disease, and the IFAT was highly useful in detecting TCE serum antibodies of turkey flocks that had recovered and were potential carriers. Therefore, an IFAT surveillance program was instituted for replacement flocks on farms where clinical epiornithics of TCE had occurred in 1974 through 1976. Operation 5 involved TCE epiornithics over a 2-year period and illustrate the importance of complete depopulation with an intensive decontamination program.

Scanning electron, light, and immunofluorescent microscopy of coronaviral enteritis of turkeys (Bluecomb).

Intestinal sections from both experimental and field cases of turkey coronaviral enteritis (TCE) were examined by scanning electron microscopy and light microscopy through 10 days after inoculation and by a direct fluorescent antibody test for TCE through 12 days. Serums were collected for an indirect fluorescent antibody test for TCE through 160 days after inoculation. Lesions observed with the scanning electron microscopy were catarrhal enteritis with hemorrhage per diapedesis, epithelial desquamation, and villous atrophy which developed and regressed within 6 days after inoculation. Light microscopy demonstrated similar lesions, except that villus-to-crypt ratios remained depressed 10 days. The direct fluorescent antibody test demonstrated the presence of coronaviral antigen throughout the sampling period, and serum antibodies to TCE were present until at least 160 days, when the experiment was terminated.

Histopathology of fasting and bluecomb disease in turkey poults and embryos experimentally infected with bluecomb disease coronavirus.

The histopathology of fasting and bluecomb disease in one-day-old turkey poults inoculated with bluecomb disease coronavirus (BCDCV) was studied. Uninoculated fasting poults produced clinical signs similar to those observed in BCDCV-inoculated poults. No histological changes in the intestines were observed in the fasted poults whereas definite lesions were observed in the BCDCV-inoculated poults. The lesions did not differ significantly with whether they were fed or fasted. The severity of the lesions in the intestinal epithelium was in decreasing order in the jejunum, ileum, and cecum. The lesions first appeared 24 hours postinoculation (PI) and progressed through 96 hours PI, as marked shortening of the villi, loss of microvilli, granular appearance of the cytoplasm of epithelial cells with nuclear margination of chromatin, and accentuation of the nucleolus. Similar lesions were observed in the jejunum, ileum, and cecum of turkey embryos inoculated at 24 days old as well as poults from these embryos. Signs of healing were first seen at 120 hours PI. No histopathological changes were observed in the pancreas, brain, kidneys, liver, adrenal, and bursa of Fabricius. The intestinal lesions observed should be a useful histological technique for differentiating fasting from bluecomb disease in turkey poults.

Indirect fluorescent antibody test for the diagnosis of coronaviral enteritis of turkeys (bluecomb).

Frozen sections of intestine obtained from experimentally infected embryos were satisfactory as a suitable antigen in the indirect fluorescent antibody (IFA) test for detection of antibodies to turkey coronaviral enteritis (TCE). Antibodies were detected in infected turkeys at 14 days after infection and persisted for at least 107 days when the 1st experiment was concluded. Antibodies were also detected in infected turkeys at 9 days after infection and persisted for at least 160 days when the 2nd experiment was terminated. The IFA test may be of value as a rapid and economical screening method for TCE antibodies.

Fluorescent antibody test for rapid diagnosis of coronaviral enteritis of turkeys (bluecomb).

Intestinal tissues obtained from coronavirus-infected embryos and turkeys were examined by fluorescent antibody tissue section technique (FAT). Evidence of viral antigen was demonstrated in the cytoplasm of the intestinal epithelial cells covering the villi. Embryo intestines that were examined from 24 to 96 hours after inoculation were positive for immunofluorescence (IF), whereas bursa of Fabricius was negative. Poults hatched from infected embryos were examined at 2 days of age and were positive for IF. Coronaviral antigen was detected by FAT in the cytoplasm of intestinal epithelial cells of the jejunum, ileum, duodenum, and cecum in all turkeys that were examined from 24 hours to 28 days.

Immunity to transmissible (coronaviral) enteritis of turkeys (bluecomb).

Turkey flocks recovering from natural and laboratory induced coronaviral enteritis developed lifelong immunity. Virus neutralization tests indicated that neutralization capacity of serums from recovered turkeys was low. One-way cross challenge test using turkeys inoculated with various bluecomb isolates revealed close antigenic relationship or antigenic identity among bluecomb isolates. The controlled application of intestinal preparations containing coronavirus as a vaccination procedure had value in developing active lasting immunity but it has limitations in areas that are attempting to eliminate the disease by a depopulation program. Killed vaccines injected parenterally did not produce a detectable immunity.