Development of a multispecies identification field test by modified agar-gel immunodiffusion.

A multispecies identification field test (MULTI-SIFT) was developed for detection of beef, poultry, pork, sheep, horse, and deer in a wide variety of raw meat products. The test is an adaptation of previously developed field screening immunodiffusion tests for detection of single species. MULTI-SIFT was demonstrated to be specific, relatively sensitive, and accurate in the complete speciation of 100 meat samples.

Correlation of water activity and other environmental conditions with repeated detection of Salmonella contamination on poultry farms.

Three flocks on 13 different broiler farms were monitored for Salmonella over three consecutive growout periods using the drag swab (DS) technique. One house was consistently negative for Salmonella contamination (7.7%); four houses were consistently positive (30.8%); and eight houses (61.5%) alternated between either a DS Salmonella-negative or -positive status. Simultaneously, numerous environmental parameters of the litter surface were measured, including water activity (Aw), ammonia, temperature, pH, moisture content (MC), ash content, and volatile solids. Analysis of these data as a corollary to either Salmonella-negative or -positive DS results revealed significant correlation coefficients for some of the parameters, especially Aw. The results suggest that there should be further exploration of remedial intervention based on control of some of the physical features of litter (e.g., controlling litter Aw and possibly MC and pH levels) in poultry houses.

The effect of exposure, storage times, and types of holding media on the drag-swab monitoring technique for Salmonella.

Four maintenance media were compared for the preservation of the sensitivity of drag swabs and to assess the survival of Salmonella spp. on drag swabs at reduced temperatures. The effects of Difco double-strength skim milk (2 x SM), 2% buffered peptone water (BPW), a modified liquid Cary-Blair transport medium (LCB), and lactose broth holding medium were compared, as were storage periods of various lengths. The results with enzyme-linked immunosorbent antigen capture assay and highly selective plating media detection systems showed that 2 x SM had the highest level of recovery of salmonellae after prolonged storage, both under refrigeration at 4 C for 3 days and under frozen conditions of -15 C for 2 weeks.

Development of a rapid equine serological test (REST) by modified agar-gel immunodiffusion.

A rapid equine serological test (REST) has been developed for detection of horse meat in a wide variety of raw meat products. The test is an adaptation of previously developed field screening immunodiffusion tests for beef, poultry, pork, and sheep detection. Results show that the REST test was specific, sensitive, and accurate in the analysis of 101 samples.

The isolation of salmonellae from poultry environmental samples by several enrichment procedures using plating media with and without novobiocin.

A two-part study was conducted to examine the efficacy of several enrichment-broth techniques and of plating media for detecting salmonellae from poultry environmental samples. The data are reported on pooled samples collected from five poultry houses. The samples were cultured for salmonellae, using up to four different enrichment procedures and employing plating media with and without novobiocin. The primary enrichment-broth procedures were: 1) buffered peptone water preenrichment to Hajna's tetrathionate (TT) broth; and 2) direct inoculation in TT broth. The delayed secondary-enrichment procedure involved prolonged incubation at room temperature and transfer of the primary broths. The plating media consisted of: 1) xylose lysine desoxycholate agar (XLD); 2) xylose lysine desoxycholate agar containing 15 or 20 micrograms per mL of novobiocin (XLDN); 3) brilliant green sulfapyridine agar (BGSP); and 4) brillant green agar containing 20 micrograms per mL of novobiocin (BGN). Of the 94 Salmonella-positive recoveries from the enrichment broths in which complete comparisons could be made, an average of 75% were recovered from the primary enrichment broths and an average of 86% were recovered from the delayed secondary-enrichment broths. Of the 254 Salmonella-positive isolations in which complete comparisons could be made, an average of 65% were isolated on the plating media without novobiocin and an average of 97% were isolated on the plating media containing novobiocin. Overall, the delayed secondary enrichment and enteric plates supplemented with novobiocin significantly improved Salmonella detection from the farm environmental samples.

Development of serological ovine field test (SOFT) by modified agar-gel immunodiffusion.

A serological ovine field test (SOFT) has been developed for detection of lamb or sheep tissue in a wide variety of raw meat products. The test is an adaptation of previously developed field screening immunodiffusion tests for beef, poultry, and pork detection. The SOFT test was demonstrated to be specific, sensitive, and accurate in the analysis of 104 samples.

Development of porcine rapid identification method (PRIME) by modified agar-gel immunodiffusion.

A porcine rapid identification method (PRIME) has been developed for detection of pork in a wide variety of meat products. The test is an adaptation of previously developed field screening immunodiffusion tests for beef and poultry detection. The PRIME test was demonstrated to be specific, sensitive, and accurate in the analysis of samples in the laboratory and in a commercial meat processing establishment.

Detection of poultry and pork in cooked and canned meat foods by enzyme-linked immunosorbent assays.

Enzyme-linked immunosorbent assays (ELISA) are described for the detection of poultry and pork in cooked and canned meat foods. These assays are based on species-specific, polyclonal antibodies raised against heat-resistant antigens. The heat-resistant antigens were isolated from raw skeletal muscle tissue of pork and chicken and were found to be immunoreactive even after heating to 120 degrees C for 15 min. The poultry ELISA could detect chicken or turkey at the 126 ppm level, and the pork ELISA could detect pork at the 250 ppm level. Samples of frankfurters, bolognas, pressed meats, canned baby foods, and canned spreads were prepared by simple aqueous extractions.

Selective Procedure for Detection of Salmonellae from Poultry and Sausage Products.

The efficacy of lactose preenrichment and various selective enrichment and differential plating media were evaluated to determine the optimal procedure for detecting salmonellae from fresh chicken or frozen turkey, pork sausage, and cured chicken. Salmonellae were most frequently recovered from fresh poultry or pork sausage when samples were preenriched in lactose broth incubated at 35°C, selectively enriched in TT broth at 43°C, and streaked onto a new differential plating medium, modified lysine iron agar (MLIA/USDA). Enrichment of cured chicken in selenite brilliant green broth incubated at 43°C was more productive than in TT incubated at 43°C. When poultry and sausage samples were first preenriched at 35°C, selectively enriched at 43°C, and then streaked onto MLIA/USDA greater than 75% of all CFUs on the MLIA/USDA plates were typical of salmonellae. Different procedures are recommended for maximal recovery of salmonellae from fresh, frozen or cured poultry products.

Detection of beef and poultry by serological field screening tests (ORBIT and PROFIT): collaborative study.

Ten laboratories each analyzed 30 raw meat and raw meat product samples in a collaborative study of the ORBIT (overnight rapid bovine identification test) and PROFIT (poultry rapid overnight field identification test) serological field screening tests for the detection of beef and poultry. Versatility of the tests was shown in the analysis of whole tissue, ground, or emulsified raw meat products. Both tests were demonstrated to be reliable and were capable of detecting adulterants present at the 10% level. The method has been adopted official first action.

Development of poultry rapid overnight field identification test (PROFIT).

A poultry rapid overnight field identification test (PROFIT) has been developed as a screening test which is practical, economical, and easy to perform and interpret for use in field environments to determine the presence of poultry tissue (chicken and turkey) in raw whole tissue or ground/formulated meat products. The basis of the test is an agar-gel immunodiffusion technique used with a printed template pattern and stabilized reagent paper discs. The test shows adequate sensitivity and specificity for its intended purpose. Key components are stable for at least 1 year if they are stored at refrigerator conditions. The design of the test is such that it can be made commercially available as a complete, stable, test kit suitable for use by any type of inspection program concerned with verification of poultry species in meat and/or poultry products that are subject to regulatory or quality controls.

Development of an overnight rapid bovine identification test (ORBIT) for field use.

An Overnight Rapid Bovine Identification Test (ORBIT) has been developed as a serological screen test for species verification of raw, whole tissue, bovine meat products. The test, an agar-gel immunodiffusion technique, uses stabilized reagent paper discs and prepared agar plates that have a printed template for correct placement of test components. This test is reliable, practical, economical, and easily performed in the field, such as at a meat import inspection station. The only nonbovine species found to react in the test are the bovine-related species of American bison (buffalo) and water buffalo (from Australia); however, these rare-occurring species do not present a problem for the intended application of the test. Stability of all test components, when stored in a refrigerator, is excellent for at least 1 year. The nature and stability of the test make it suitable for commercial development into test kits which should be highly practical and economical for wide availability and application of this procedure to meat inspection programs concerned with species verification.

Effects of the evisceration and cooling processes on the incidence of Salmonella in fresh dressed turkeys grown under Salmonella-controlled and uncontrolled environments.

In July and December 1981, turkeys grown in a Salmonella-free environment were sampled at the end of the slaughter and evisceration processes to determine the effect of slaughter and evisceration on the incidence of Salmonella in raw, eviscerated turkeys. A total of 109 eviscerated turkeys from the Salmonella-free flocks and 79 control turkeys were sampled. A total of 75 environmental swab samples and 5 chiller water samples were collected. Less than 1% of the eviscerated Salmonella-free turkeys were Salmonella positive and 6.3% of the eviscerated control turkeys were Salmonella positive. The results of the swab samples indicated generally good processing equipment sanitation.

Detection and quantitation of chloramphenicol by competitive enzyme-linked immunoassay.

A competitive enzyme-linked immunoassay for the detection and quantitation of chloramphenicol has been developed. The binding of specific rabbit antibody to solid-phase-bound chloramphenicol was competitively inhibited by free chloramphenicol in the sample to be assayed. Antibody not displaced was indicated by using a commercially available, enzyme-linked, anti-rabbit immunoglobulin preparation and reacted with added substrate. Enzyme activity, measured spectrophotometrically, was inversely proportional to the concentration of chloramphenicol in the sample. Quantitation of the antibiotic was linear to 100 ng/ml, with a lower limit of detection of 1 ng/ml (P less than 0.05). Specificity was demonstrated by the lack of inhibition by any of 31 selected antimicrobial agents or chemicals tested in the assay. Chloramphenicol sodium succinate and thiamphenicol, an experimental antibiotic similar in structure to chloramphenicol, were the only drugs found to produce cross-reactions. In addition to excellent sensitivity and specificity, the assay was shown to have good precision and economy and could be completed in approximately 24h.

The microbiology of raw, eviscerated chickens: a ten year comparison.

In 1979 a survey of selected chicken eviscerating plants was conducted to determine the levels of coliforms, Escherichia coli, and Salmonellae sp. on eviscerated chickens under current manufacturing practices. A comparison was made of the data from this survey and one conducted in 1969. The 1979 survey found that the chickens did not have a statistically significant reduced incidence of salmonella compared to chickens analyzed in 1969. Also, much of the bacterial contamination on a carcass at the end of the evisceration line was transient and was readily removed by the final spray washer. The addition of chlorine to chiller water did not appear to have an unusually beneficial effect on the microbiological quality of the chickens. In 1969, in the nine plants studied, the incidence of salmonella on chickens at the exit of the chillers was 20.5%. In 1979, in the nine plants studied, the incidence of salmonella on chickens at the exit of the chillers was 11.6%. In 1979 there was about a 45% reduction in the incidence of salmonella in eviscerated chickens in the nine plants studied compared to the incidence of salmonella in eviscerated chickens in 1969.

Incidence of Salmonella in fresh dressed turkeys raised under Salmonella-controlled and uncontrolled environments.

The incidence of salmonella in turkeys from experimental salmonella-controlled and uncontrolled, or normal, flocks processed at three turkey slaughter plants were compared. The results indicate that processing salmonella-controlled turkeys in a plant that routinely kills normal birds may result in the contamination of the salmonella-controlled birds, probably due to salmonella in the plant environment. The salmonella-controlled turkeys studied tended to have a lower incidence of salmonella than normal birds. These observation indicate that salmonella control practices in turkey raising can result in a salmonella reduction in market birds even under existing commercial slaughter, evisceration, and cooling procedures.

The incidence of Salmonella species and serotypes in young whole chicken carcasses in 1979 as compared with 1967.

A survey was conducted to determine the incidence of salmonellae in processed, ready-to-market, whole young chickens. Carcasses from 15 federally inspected chickens eviscerating plants were analyzed using a carcass washing technique for determining the presence of salmonellae. The results obtained during the 1979 incidence survey were compared to results obtained in an identical 1967 Salmonella survey. In the 1967 study, salmonellae were isolated from 171 ot the 597 (28.6%) whole chickens tetrathionate broth rinsings analysed. In the 1979 study, 222 of 601 (36.9%) of similarly analysed chicken samples were positive. Percentile positive findings from individual plants range from 7.5 to 73.7% in 1967 and from 2.5 to 87.5% in 1979.

A Comparative Study of the Microbiology of Commercial Vacuum-Packaged and Hanging Beef.

The microbiological quality of 150 samples of commercial vacuum-packaged beef knuckles and 150 samples of non-vacuum-packaged hanging beef knuckles were tested. Samples were obtained at random from commissaries at several locations just before distribution of the beef to retail stores. In general, the vacuum-packaged beef had 1 to 2 logs higher indicator bacterial levels than the hanging beef. The odor and appearance of all 300 samples of beef were normal, even though some individual beef samples had rather high bacterial counts. Salmonella was detected in only 1 sample out of all the 300 tested. Yersinia enterocolitica was recovered from 66 samples of vacuum-packaged beef and from only 4 samples of hanging beef. None of the Y. enterocolitica recovered from beef contained the virulence plasmid or were virulent to mice. Most probably these rhamnose-positive and esculin-positive Y. enterocolitica strains recovered from vacuum-packaged beef are not a potential health hazard.