Clinical, histologic, and bacteriologic findings in dairy cows with digital dermatitis (footwarts) one month after topical treatment with lincomycin hydrochloride or oxytetracycline hydrochloride.

OBJECTIVE: To compare the effectiveness of lincomycin and oxytetracycline for treatment of digital dermatitis (DD) in dairy cows through gross visual examination, histologic evaluation, and bacteriologic evaluation. DESIGN: Randomized controlled clinical trial. ANIMALS: 25 cows with DD lesions from a commercial Holstein dairy herd. PROCEDURES: Cows with DD lesions were randomly assigned to 1 of 3 groups: topical treatment with 10 g of lincomycin hydrochloride (n = 11), topical treatment with 10 g of oxytetracycline hydrochloride (11), and no treatment (3) on days 1 and 2 (d1). Biopsy specimens were obtained for histologic examination from DD lesions prior to treatment and 28 or 31 days (d30) after treatment for histologic examination. Cows were clinically examined on d1, days 12 or 14 (d14), and d30. RESULTS: No difference was evident in clinical responses to lincomycin and oxytetracycline, so data were pooled; at d30, 8 of 11 of lincomycin-treated lesions and 7 of 11 oxytetracycline-treated lesions appeared visually healed, respectively. Gross visual examination suggested 73% (16/22) of treated cows were healed at d14 and 68% (15/22) of treated cows were healed on d30. Of the 15 lesions that appeared healed on d30, 7 of 15 were classified histologically as active (ulceration and bacterial invasion; 2/15) or incipient (5/15). CONCLUSIONS AND CLINICAL RELEVANCE: Clinical responses to lincomycin and oxytetracycline did not differ. Agreement was good between gross visual and histologic assessments of DD lesions before treatment; agreement 1 month after treatment was variable. Histologic evaluation could not distinguish incomplete healing from lesion recurrence.

Mycotic pododermatitis and mycotic pneumonia in commercial turkey poults in northern California.

Seven 5-week-old broad-breasted white commercial meat turkeys were submitted to the California Animal Health and Food Safety laboratory in Turlock with a history of respiratory illness. The primary diagnostic findings were mycotic pododermatitis and mycotic pneumonia. The unique feature of this case was the colonization of footpad epidermis and subcutis by fungal hyphae in commercial turkey species. No fungal cultures were undertaken at the time of the necropsy; therefore, paraffin-embedded tissue sections of lung and footpads were used to extract, amplify, and sequence mycotic DNA. A mixed population of fungi was identified in both lung and footpads by polymerase chain reaction amplification of part of the large subunit ribosomal RNA gene using broad-range fungal primers and DNA sequencing. In footpads, sequences matching Cryptococcus saitoi and Cladosporium and Cudoniella species were identified. It is believed that these fungi were opportunistic pathogens originating from the litter. The fungi identified from lungs were Aspergillus species, most closely matching Aspergillus flavus and Arxiozyma telluris (most likely a contaminant). Mycotic pododermatitis in avian species is considered a rare pathologic finding, and few documented reports are available. The on-farm prevalence of footpad lesions was estimated at 3%, and there was no associated increase in the incidence of lameness or weight depression in affected birds. Microscopically, a granulomatous inflammatory reaction associated with fungal hyphae was observed in lung parenchyma. Disruption of keratinized epidermis, encrustations, and acute inflammation were also noted in footpads invaded with fungal hyphae.

Recovery of Salmonella, Listeria monocytogenes, and Mycobacterium bovis from cheese entering the United States through a noncommercial land port of entry.

A joint multiagency project was initiated in response to a Salmonella outbreak in San Diego County, California, in 2004. Samples of cheese were collected during four 1-day operations at the San Ysidro port of entry, along the United States-Mexico border. Surveyed participants were persons crossing the border as pedestrians or in vehicles who had a minimum of 2.27 kg of cheese, which may suggest a potential diversion to illegal marketing. In addition, data were collected about the cheese to identify risk factors for cheese contamination. Two hundred four cheese samples were submitted to the California Animal Health and Food Safety Laboratory System-San Bernardino Branch and analyzed for potential food pathogens. Ninety-four percent (190 of 203) of the samples tested positive for alkaline phosphatase. Salmonella was detected from 13% (27 of 204) of the samples comprising 11 serogroups and 28 serotypes. Pulsed-field gel electrophoresis DNA fingerprinting analysis, performed following standardized methods, determined that an isolate obtained from this study had an indistinguishable pattern from a recent Salmonella enterica serovar Typhimurium var. Copenhagen epidemic in the San Diego County that was linked to 14 illnesses. Listeria spp. were detected from 4% (8 of 204) of the samples, and of these, half were identified as L. monocytogenes. Escherichia coli O157:H7 was not detected from any of the samples. Mycobacterium bovis was detected from one panela-style cheese sample. Nine additional samples yielded Mycobacterium spp.

Comparison of a Salmonella enteritidis-specific polymerase chain reaction assay to delayed secondary enrichment culture for the detection of Salmonella enteritidis in environmental drag swab samples.

The California Egg Quality Assurance Program uses the delayed secondary enrichment culture method for detecting Salmonella Enteritidis in environmental drag swabs obtained from commercial layer complexes. The turnaround time for this method is variable and is dependent on the prevalence of Salmonella, level of the Salmonella identification, and capabilities of the performing laboratory. On a sample basis, a range of 4 to 8 days is required to identify a Salmonella sp. to the serogroup level. Additional time is required to serotype group D Salmonella isolates. A Salmonella Enteritidis-specific polymerase chain reaction (PCR) assay was developed for use on drag swabs and chick box papers, and had a turnaround time of 3-4 days. The delayed secondary enrichment culture method and the Salmonella Enteritidis-specific PCR assay were compared on 942 drag swab and 85 chick box paper samples submitted from 217 and 22 premises, respectively, as part of the California Egg Quality Assurance Program. The PCR assay identified 43 positive Salmonella Enteritidis samples from 22 premises, whereas the culture method identified 24 group D Salmonella-positive samples from 16 premises. There was a significant difference (P = 0.001) in the proportion of positive samples as determined by the two assays. Complete serotyping of the group D Salmonella-positive cultures confirmed Salmonella Enteritidis in all but one sample that was identified as Salmonella Jamaica and was negative by the PCR assay.

Experimental transmission of epizootic bovine abortion (foothill abortion).

Advances in defining the biology of epizootic bovine abortion (EBA), including identification of the etiologic agent, have been hampered by the inability to reproduce the disease with confidence. Experimental reproduction of EBA, by feeding the tick vector Ornithodoros coriaceus on susceptible pregnant heifers, is not reliable. The primary objectives of this study were to identify specific tissue(s) obtained from EBA-infected fetuses that could transmit the disease, and then utilize such an infectious challenge system to better define the pathogen, host immunity and geographic distribution of the agent. Described here is the ability to routinely reproduce EBA following inoculation of cryopreserved suspensions of homogenized thymus into susceptible pregnant heifers. This challenge system permitted experiments demonstrating the agent was non-filterable, inactivated upon sonication and susceptible to antibiotics. These findings suggest a prokaryotic microbe and represent a major advance in EBA research. Additional experiments demonstrated that inoculation of the cryopreserved EBA-infectious tissue into heifers, prior to breeding, conferred immunity. Furthermore, such immunized heifers were resistant to challenge with heterologous sources of infectious tissue, suggesting monovalent vaccine development might be feasible. Lastly, challenge studies employing animals from Central Nevada, an area considered free of EBA, demonstrated partial immunity, suggesting the pathogen, and possibly the disease, enjoy a broader distribution than previously thought.

Identification of trichomonadid protozoa from the bovine preputial cavity by polymerase chain reaction and restriction fragment length polymorphism typing.

Accurate identification of the bovine pathogen Tritrichomonas foetus is sometimes complicated by the presence of other trichomonadid protozoa in clinical samples. A highly specific and reproducible approach for differentiating 3 common types of bovine trichomonadid protozoa found in the bovine preputial cavity, T. foetus, Pentatrichomonas hominis, and a Tetratrichomonas species, was developed using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis. Universal trichomonadid protozoa primers, TFR1 and TFR2, were used to amplify the 5.85 rRNA gene and internal transcribed spacer regions (ITSRs), and the products were digested with the restriction enzyme HpyCH4IV. Restriction fragment length polymorphism analysis was performed on 55 trichomonad isolates from bovine preputial washing and scraping samples. The RFLP results correlated 100% with 5.85 rRNA gene and ITSR sequence resultsand PCR results with primers specific for T. foetus. The results of this study demonstrate that PCR and RFLP analysis can be used in lieu of DNA sequencing to identify the specific trichomonadid protozoa isolated from the bovine preputial cavity.

Determination of the median toxic dose of type C botulinum toxin in lactating dairy cows.

Because of the difficulty in identifying botulinum toxin in cattle, it is hypothesized that cattle are sensitive to levels of toxin below the detection limits of current diagnostic techniques (the mouse protection bioassay and the immunostick enzyme-linked immunosorbent assay [ELISA] for type C botulinum toxin). Using an up-down method for toxicologic testing, the median toxic dose (MTD50) for cattle was determined. Four lactating Holstein cows were dosed at 0.125 or 0.25 ng/kg with Clostridium botulinum type C toxin and failed to develop clinical signs of botulism during the 7-day observation period. Three cows given 0.50 ng/kg of toxin developed clinical signs of botulism. From these results, the MTD50 was calculated at 0.388 ng/kg (3.88 mouse lethal doses/kg) using the trim-logit method. These results suggest that cattle are 12.88 times more sensitive to type C botulinum toxin than a mouse on a per kilogram weight basis. The mouse protection bioassay and the immunostick ELISA for type C botulinum toxin failed to identify the presence of the toxin in the serum, blood, and milk samples taken from all 7 animals.

Diagnosis of avian mycobacteriosis: comparison of culture, acid-fast stains, and polymerase chain reaction for the identification of Mycobacterium avium in experimentally inoculated Japanese quail (Coturnix coturnix japonica).

In this study we compared culture, acid-fast stains, and polymerase chain reaction (PCR) for the detection of acid-fast organisms in fecal and tissue samples from Japanese quail (Coturnix coturnix japonica) that were experimentally inoculated intravenously with Mycobacterium avium. For culture, three different culture media (modified Herrold egg yolk with mycobactin; Lowenstein-Jensen [L-J]; and L-J with cyclohexamide, naladixic acid, and lincomycin) were tested to determine which medium had the greatest success in isolating mycobacteria. Acid-fast staining methods included Zichl-Neelsen (Z-N) and Truant. The PCR assay detected mycobacterial DNA with primers specific for the 65-kD heat shock protein gene. Culture was considered the "gold standard." Compared with other culture media, L-J yielded more positive cultures and greater numbers of colonies on positive tubes, and incubation times were shorter. Mycobacterium avium was isolated from all of the harvested tissue samples (liver, spleen, and intestine) of inoculated birds. Mycobacteria were isolated from 53% (69/130) of fecal samples from inoculated birds. As the disease advanced, fecal culture was positive on more culture days, indicating that the culture-positive rate was higher later in the course of the disease. Compared with culture, all of the laboratory methods had 100% specificity for the tissue samples. Sensitivities for the tissue samples were 82.6% (Z-N), 95.7% (Truant), and 100% (PCR). For the fecal samples, the specificity was >95% for all methods. Sensitivities compared with fecal culture were 7.2% (Z-N), 30.4% (Truant), and 20.3% (PCR). Tissue and fecal samples from the two control birds were negative for acid-fast organisms by any method. These results were comparable with clinical cases of avian mycobacteriosis where culture and PCR of tissue samples seem to be the most sensitive and specific laboratory tests and evaluation of fecal samples still remains challenging. On the basis of the results of this study, identification of mycobacteria in fecal samples from Japanese quail can be optimized by repeated cultures and Truant acid-fast staining of fecal smears.

Comparison of four rapid DNA extraction techniques for conventional polymerase chain reaction testing of three Mycobacterium spp. that affect birds.

Mycobacteriosis is an avian disease that is most commonly caused by Mycobacterium avium or Mycobacterium genavense. In order to optimize molecular laboratory tests for diagnosing mycobacteriosis in birds, we compared four methods of rapid DNA extraction with isolates of M. avium, M. genavense, and Mycobacterium fortuitum. DNA extraction methods included enzymatic lysis, boiling for 30 min followed by enzymatic lysis, four cycles of freezing and thawing followed by enzymatic lysis, and bead beating followed by enzymatic lysis. The DNA yield and purity for the four methods were evaluated by spectrophotometry and compared. The bead beating with enzymatic lysis technique yielded significantly purer and higher concentrations of extracted DNA compared with other DNA extraction methods. All four methods yielded extraction products for all three organisms that were successfully amplified by polymerase chain reaction (PCR) for a fragment in the 65-kD heat shock protein gene. Subjectively, the PCR amplification products were most abundant for samples extracted by bead beating with enzymatic lysis.

A model of avian mycobacteriosis: clinical and histopathologic findings in Japanese quail (Coturnix coturnix japonica) intravenously inoculated with Mycobacterium avium.

Mycobacterial infections are an important cause of morbidity and mortality in birds and a considerable diagnostic challenge until the disease is advanced. In order to develop more clinically useful antemortem tests, a biological model was created that replicated naturally occurring disease. Japanese quail (Coturnix coturnix japonica; n = 8) were inoculated intravenously with Mycobacterium avium. Two additional birds served as uninoculated controls. Mean survival time of the inoculated birds was 68 +/- 13 days postinoculation (PI). Seven of the eight inoculated birds died naturally. Clinical and postmortem abnormalities in inoculated birds were characteristic of naturally occurring mycobacteriosis. Abnormal clinical findings included decreased activity, feather erection, and sudden death. Mean body weight and packed cell volume declined and mean total white blood cells (primarily heterophils, bands, and monocytes) increased from 28 days PI onward. Similar to birds that are naturally infected with mycobacteriosis, the inoculated birds were thin and had severe hepatosplenomegaly on postmortem examination. All eight birds had lesions in the liver, spleen, intestine, lung, gonads, and serosa. Less commonly affected tissues included bone marrow, thymus, gizzard, heart, pancreas, and brain. Lesions were invariably severe in the liver and spleen. These gross postmortem findings were consistent with natural infections of avian mycobacteriosis. Mycobacterium avium was isolated from the liver, spleen, and intestine of all inoculated birds. Both control birds remained disease free and culture negative. This inoculation protocol is a reliable and practical means of inducing avian mycobacteriosis for further study.

Identification of variations in SzP proteins of Streptococcus equi subspecies zooepidemicus and the relationship between protein variants and clinical signs of infection in horses.

OBJECTIVE: To determine whether previously unidentified variations of the SzP protein of Streptococcus equi subsp zooepidemicus were present in horses with various clinical signs of infection and whether any relationship could be identified between SzP protein variants and naturally occurring clinical conditions. SAMPLE POPULATION: 23 isolates of S equi subsp zooepidemicus were recovered from specimens of horses with various clinical conditions and used as a representative population of isolates for evaluation of different SzP protein variants. PROCEDURE: Genetic heterogeneity of the isolates was demonstrated by repetitive extragenic palindromic-polymerase chain reaction analysis. The SzP gene was sequenced and the presumed protein sequence determined for each isolate. Characteristics of the SzP proteins were compared among the isolates and in relation to the clinical conditions of horses from which they were recovered. RESULTS: The signal peptide types, number of proline-glutamic acid-proline-lysine repeats, and anchor sequences were consistent with those previously described for the SzP protein. Many of the isolates clustered with 5 previously described types on the basis of the hypervariable region of the SzP protein. One additional variant, which represented 8 of the isolates, was identified. Particular motifs in the hypervariable region accounted for many of the differences among hypervariable types. CONCLUSIONS AND CLINICAL RELEVANCE: The SzP protein appears to be limited to a selected number of types. Variations in the SzP protein are frequently determined on the basis of different motifs rather than random amino acid substitutions. There does not appear to be any association of SzP protein variations and clinical manifestations of infection in horses.

Evaluation of microbial culture of pooled fecal samples for detection of Mycobacterium avium subsp paratuberculosis in large dairy herds.

OBJECTIVE: To evaluate sensitivity of microbial culture of pooled fecal samples for detection of Mycobacterium avium subsp paratuberculosis (MAP) in large dairy herds and assess the use of the method for estimation of MAP prevalence. ANIMALS: 1,740 lactating cows from 29 dairy herds in California. PROCEDURE: Serum from each cow was tested by use of a commercial ELISA kit. Individual fecal samples were cultured and used to create pooled fecal samples (10 randomly selected fecal samples/pool; 6 pooled samples/herd). Sensitivity of MAP detection was compared between Herrold's egg yolk (HEY) agar and a new liquid culture method. Bayesian methods were used to estimate true prevalence of MAP-infected cows and herd sensitivity. RESULTS: Estimated sensitivity for pooled fecal samples among all herds was 0.69 (25 culture-positive pools/36 pools that were MAP positive). Sensitivity increased as the number of culture-positive samples in a pool increased. The HEY agar method detected more infected cows than the liquid culture method but had lower sensitivity for pooled fecal samples. Prevalence of MAP-infected cows was estimated to be 4% (95% probability interval, 2% to 6%) on the basis of culture of pooled fecal samples. Herd-level sensitivity estimate ranged from 90% to 100% and was dependent on prevalence in the population and the sensitivity for culture of pooled fecal samples. CONCLUSIONS AND CLINICAL RELEVANCE: Use of pooled fecal samples from 10 cows was a cost-effective tool for herd screening and may provide a good estimate of the percentage of MAP-infected cows in dairy herds with a low prevalence of MAP.

Risk factors for Clostridium piliforme infection in foals.

OBJECTIVE: To determine risk factors for Clostridium piliforme infection in neonatal foals on a Thoroughbred breeding farm in California. DESIGN: Case-control and retrospective cohort studies. ANIMALS: 322 neonatal Thoroughbred foals either born on the study farm or born elsewhere but traveled to the farm with their dam during the 1998, 1999, and 2000 breeding seasons. PROCEDURE: Mare and foal records from 1998, 1999, and 2000 were examined, using case-control design methods to determine variables associated with increased risk of C. piliforme infection in foals. Important risk factors identified in the case-control study were then reevaluated by use of a retrospective cohort design, using data from all neonatal foals present on the farm during the 3-year study period. RESULTS: Foals born between March 13 and April 13 were 7.2 times as likely to develop C. piliforme infection as were those born at any other time of the foaling season. Foals of nonresident (visiting) mares were 3.4 times as likely to develop disease as were foals born to mares that were permanent residents of the study farm. Foals of mares < 6 years of age were 2.9 times as likely to develop disease as were foals born to older mares. CONCLUSIONS AND CLINICAL RELEVANCE: Results of this research can be used to better understand the epidemiologic factors of C. piliforme infection in horses. High-risk foals can be closely monitored to aid in early diagnosis and treatment, resulting in the best possible clinical outcome for affected individuals.

Genome degradation in Brucella ovis corresponds with narrowing of its host range and tissue tropism.

Brucella ovis is a veterinary pathogen associated with epididymitis in sheep. Despite its genetic similarity to the zoonotic pathogens B. abortus, B. melitensis and B. suis, B. ovis does not cause zoonotic disease. Genomic analysis of the type strain ATCC25840 revealed a high percentage of pseudogenes and increased numbers of transposable elements compared to the zoonotic Brucella species, suggesting that genome degradation has occurred concomitant with narrowing of the host range of B. ovis. The absence of genomic island 2, encoding functions required for lipopolysaccharide biosynthesis, as well as inactivation of genes encoding urease, nutrient uptake and utilization, and outer membrane proteins may be factors contributing to the avirulence of B. ovis for humans. A 26.5 kb region of B. ovis ATCC25840 Chromosome II was absent from all the sequenced human pathogenic Brucella genomes, but was present in all of 17 B. ovis isolates tested and in three B. ceti isolates, suggesting that this DNA region may be of use for differentiating B. ovis from other Brucella spp. This is the first genomic analysis of a non-zoonotic Brucella species. The results suggest that inactivation of genes involved in nutrient acquisition and utilization, cell envelope structure and urease may have played a role in narrowing of the tissue tropism and host range of B. ovis.

Malassezia slooffiae-associated dermatitis in a goat.

An adult male Pygmy goat with a history of losing hair and declining body condition was euthanized, and a complete diagnostic work-up was performed. The animal showed diffuse alopecia on the dorsal and lateral sides of thorax and abdomen, proximal legs, neck and face. Histology revealed diffuse orthokeratotic hyperkeratosis, epidermal hyperplasia and perivascular dermatitis. Broad-based budding yeasts and hyphae were visible in the keratin layer. Malassezia slooffiae was identified in the skin by polymerase chain reaction amplification of part of the large subunit rRNA gene using broad-range fungal primers and DNA sequencing. This is the first report of M. slooffiae-associated dermatitis in goats.

Morphological and molecular identification of non-Tritrichomonas foetus trichomonad protozoa from the bovine preputial cavity.

Tritrichomonas foetus is the causative agent of bovine trichomonosis. This protozoan is found in the preputial cavity of bulls and is transmitted to cows during coitus. Currently, the diagnosis of this parasite is based on microscopic examination of preputial washings or scrapings, but it was recently recognized that other trichomonads similar in size, shape, and motility to T. foetus can be present in preputial samples. Despite the serious consequences of an incorrect diagnosis for bovine trichomonosis, the precise speciation of these other trichomonads has remained uncertain. Here, a total of 12 non-T. foetus isolates were microscopically examined. On the basis of morphological criteria, seven of these isolates were identified as Tetratrichomonas sp., whereas four other isolates coincided with the description of Pentatrichomonas hominis. In the last isolate, a third non-T. foetus species was identified as belonging to the genera Pseudotrichomonas or Monocercomonas: the first time that species of either of these genera have been reported in preputial samples. To confirm these data, small subunit rRNA gene sequences were obtained by PCR from the 12 trichomonad isolates. These new sequences were analysed in a broad phylogeny including 72 other parabasalid sequences. From our phylogenetic trees, we confirmed the taxonomic status of non-T. foetus organisms isolated from preputial samples (Tetratrichomonas, Pentatrichomonas, and Pseudotrichomonas) and suggested the existence of two Tetratrichomonas species, despite their morphological similarity. The route of transmission of the non-T. foetus organisms identified in the bovine preputial cavity is discussed and we confirm that the PCR assay using the previously described T. foetus-specific primers TFR3 and TFR4 could be a useful alternative method for the diagnosis of bovine trichomonosis.

Consumption of milk from transgenic goats expressing human lysozyme in the mammary gland results in the modulation of intestinal microflora.

Lysozyme is a key antimicrobial component of human milk that has several health-promoting functions including the development of a healthy intestinal tract. However, levels of lysozyme in the milk of dairy animals are negligible. We have generated transgenic dairy goats that express human lysozyme (HLZ) in their milk in an attempt to deliver the benefits of human milk in a continual fashion. To test the feasibility of this transgenic approach to achieve a biological impact at the level of the intestine, feeding trials were conducted in two animal models. Pasteurized milk from HLZ transgenic animals was fed to both kid goats (ruminant model) and young pigs (human model), and the numbers of total coliforms and Escherichia coli present in the small intestine were determined. Data from this proof-of-principle study demonstrate that milk from transgenic animals was capable of modulating the bacterial population of the gut in both animal models. Pigs that consumed pasteurized milk from HLZ transgenic goats had fewer numbers of coliforms and E. coli in their intestine than did those receiving milk from non-transgenic control animals. The opposite effect was seen in goats. Milk from these transgenic animals not only represent one of the first transgenic food products with the potential of benefiting human health, but are also a unique model to study the development and role of intestinal microflora on health, well-being and resistance to disease.

Environmental Survey for Listeria Species in Frozen Milk Product Plants in California.

A survey of frozen milk product (FMP) plants in California was conducted to determine prevalence of Listeria spp. among plants and within specific areas in plants. Association of possible factors contributing to the presence of Listeria was analyzed. Of 922 samples, 111 (12%) were positive for Listeria spp. Listeria monocytogenes and L. innocua were the only species isolated. Of 39 plants sampled, L. monocytogenes was the only species recovered from 5 (12.8%) plants and L. innocua was the only species recovered from 13 (33.3%) plants. Both species were isolated from 9 (23.1%) plants. No Listeria was isolated from 12 (30.8%) plants. A minimum of five colonies was identified from each positive site. Only one species was identified from 105 of the 111 positive sites (94.6%). There was a statistically significant association of culture results from selected sites in plants with corresponding drain cultures; however, from 9 of 106 (8.5%) site/drain combinations no Listeria was isolated from the drain when the selected sites were positive. Type of product received and type of pasteurization did not influence recovery of Listeria from a plant. There was a significant association with size of the plant and recovery of Listeria . Level of sanitation and extent of environmental contamination control program (ECCP), individually, were not associated with recovery of Listeria from a plant. However, the rate of recovery of Listeria from plants with above average sanitation and excellent or moderate ECCP (N=7) was 6.81%, whereas the recovery rate from plants with below average sanitation and slight or no ECCP (N=7) was 27.5%. The highest recovery rates of Listeria in FMP plants were in batch flavoring, freezing and ingredient blending, and packaging filling areas.

Characterization of Treponema phagedenis-like spirochetes isolated from papillomatous digital dermatitis lesions in dairy cattle.

Four spirochete strains were isolated from papillomatous digital dermatitis (PDD) lesions in Iowa dairy cattle and compared with two previously described spirochete strains isolated from dairy cattle in California. These six strains shared an identical 16S ribosomal DNA sequence that was 98% similar to Treponema phagedenis and 99% similar to the uncultivated PDD spirochete sequence DDLK-4. The whole-cell protein profiles resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of these six strains were similar. However, these strains showed differences in the antigenic diversity of lipopolysaccharide (LPS). Genetic diversity was also detected by pulsed-field gel electrophoresis of genomic DNA digests, revealing differences among five of the six strains. Serum immunoglobulin G antibodies from dairy cattle with active PDD lesions reacted with the LPS of all but one PDD spirochete strain. Likewise, peripheral blood mononuclear cells from cattle with active PDD lesions produced blastogenic responses to one of the two California isolates. Both antibody and lymphocyte blastogenic responses were reduced in convalescent dairy cattle, suggesting the immune response to these spirochetes has short duration. These results demonstrate genetic and antigenic diversity among T. phagedenis-like treponemes and provide further evidence for the involvement of these spirochetes in the pathogenesis of PDD.