927

Journal of Protection, Vol. 68, No. 5, 2005, Pages 927±931 Copyright ᮊ, International Association for Food Protection

Escherichia coli O157:H7, jejuni, and Prevalence in Cull Dairy Cows Marketed in Northeastern Ohio

KATHRYN DODSON AND JEFFREY LEJEUNE*

Food Animal Health Research Program, Ohio Agricultural Research and Development Center, Ohio State University, Wooster, Ohio 44691, USA

MS 04-377: Received 26 August 2004/Accepted 19 January 2005

ABSTRACT Downloaded from http://meridian.allenpress.com/jfp/article-pdf/68/5/927/1670153/0362-028x-68_5_927.pdf by guest on 26 September 2021

Preharvest management factors are predicted to impact the prevalence of foodborne pathogens in cattle sent to slaughter. We simultaneously examined the prevalence and resistance patterns of Campylobacter jejuni, Salmonella, and Esch- erichia coli O157:H7 isolated from cull dairy cattle at two livestock auctions in northeastern Ohio. Between April and September 2002, a total of 1,026 fecal samples were collected. C. jejuni was isolated from 48 of 686 (7%) fecal samples, Salmonella was isolated from 39 of 585 (6.7%) samples, and E. coli O157:H7 was isolated from 21 of 1,026 (2.1%) samples. Of the 585 samples tested for all three pathogens, at least one pathogen was identi®ed in 86 of 585 (15%) samples. One sample was positive for both E. coli O157:H7 and C. jejuni, and ®ve samples yielded both C. jejuni and Salmonella. Size of herd of origin could be traced for 75 to 85% of samples collected. Salmonella was isolated at higher frequencies from herds larger than 60 cattle than from smaller herds (9.0 versus 3.5%, P ϭ 0.02). In contrast, size of herd of origin did not signi®cantly affect the E. coli O157:H7 and C. jejuni prevalence. Approximately 90% of Salmonella and E. coli O157:H7 isolates were pansensitive to a panel of 16 . Thirty-six percent of C. jejuni isolates were resistant to tetracycline. In this study, antibiotic resistance among the foodborne pathogens isolated from cull diary cattle was rare. Although size of dairy herd of origin was positively associated with Salmonella prevalence, herd size was not strongly associated with E. coli O157:H7 and C. jejuni prevalence in market dairy cattle. These results can be used to assess the risks associated with the slaughter of cull dairy cattle.

Foods of bovine origin are frequently implicated in preharvest management factors associated with the preva- outbreaks of the most common bacterial foodborne zoo- lence of these pathogens in dairy cattle have been identi- notic diseases in the United States, including campylobac- ®ed. Because of the trend for dairy cattle to be raised on teriosis, , and O157:H7 in- fewer larger farms has coincided with the increased aware- fections (2). The hooves, hide, and of ness of food safety threats in of bovine origin, public asymptomatically colonized cattle are considered the pri- concern has focused on large-scale farming as the source mary sites of foodborne pathogens. Empirical and theoret- of many food safety problems. The aim of this study was ical data suggest that lowering the prevalence of foodborne to assess the prevalence of three important foodborne path- pathogens on hides and in gastrointestinal tracts at the time ogens, Campylobacter jejuni, Salmonella, and E. coli O157: of slaughter will enhance the microbiological safety of the H7, harbored by individual cull dairy cattle and to deter- meat and thereby reduce the incidence of foodborne dis- mine the impact of size of herd of origin on the isolation eases in the human population (3, 9). Carriage of foodborne frequency and resistance to antibiotics commonly used in pathogens by dairy cattle intended for slaughter is of con- human and veterinary medicine. cern because approximately 17% of ground beef in the United States is derived from this source (27). The problem MATERIALS AND METHODS of pathogen contamination of the food supply is further Sample collection. Between April and September 2002 fecal compounded by the increase in samples of approximately 25 g each were collected per rectum among foodborne pathogens isolated from meat products from 1,026 individual mature dairy cows shortly after arrival at and cases of human illness, which makes treatment dif®cult two auction facilities in northeastern Ohio. Samples were collect- (1). ed from cull cattle presented for sale on each day, up to the lab- A thorough understanding of the factors that contribute oratory daily maximum capacity of approximately 70 samples. to frequency, magnitude, duration of excretion, and molec- Samples collected during the ®rst 13 weeks of the study were ular characterization of foodborne pathogens in animals is cultured for Campylobacter spp., Salmonella, and E. coli O157: required to devise effective on-farm intervention strategies H7. Because of predicted decreasing prevalences of Salmonella, to enhance the microbiological safety of animals intended C. jejuni, and E. coli O157:H7, respectively, increasing numbers of samples were tested for each of these pathogens to maintain for slaughter. However, few scienti®cally proven speci®c an 80% power of detecting prevalence differences between large and small farms. Salmonella isolation was not attempted after * Author for correspondence. Tel: 330-263-3739; Fax: 330-2633-677; week 13, and samples were not cultured for C. jejuni after week E-mail: [email protected]. 16. Based on sales records, attempts to ascertain size of herd of 928 DODSON AND LEJEUNE J. Food Prot., Vol. 68, No. 5 origin from the previous owner were made through direct mailings to each antibiotic tested based on interpretive criteria established and personal communications. Between the two sales facilities, by Huysmans and Turnidge (8). samples were collected on a total of 34 separate sample dates: once each week for 22 weeks from one facility and 12 times from Statistical analyses. The prevalence of each pathogen was the other facility. Samples were not collected the week of 4 July recorded. Size of herd of origin was dichotomized into large herds 2002 because no sales occurred that week. Between 2 and 69 (Ն60 lactating cows) and small herds (Ͻ60 lactating cows) by samples were collected on any given day. dividing the samples at the median of known herd sizes. A chi- square distribution test, using a type I error rate of 0.05, was used Pathogen detection. For C. jejuni isolation, cotton-tipped to determine the signi®cance of differences in prevalence for each swabs were evenly coated with feces (approximately 0.15 g) from speci®c pathogen isolated from cattle originating from known the primary collection sample, placed in 10 ml of Campy-Thio large and small herds. A chi-square test also was used to deter- (Remel, Lenexa, Kans.) enrichment broth and incubated for 48 h mine whether resistance to each antibiotic was more frequently at 4ЊC (20). The enriched samples were streaked for isolation on distributed among isolates from cattle originating from large rather Columbia blood agar containing and amphotericin B than small dairy herds. Posttest power analyses were conducted (Remel) and incubated under microaerophilic conditions for an to determine the type II error rate for falsely accepting the alter- Downloaded from http://meridian.allenpress.com/jfp/article-pdf/68/5/927/1670153/0362-028x-68_5_927.pdf by guest on 26 September 2021 additional 48 h at 42ЊC. Suspect Campylobacter colonies, based native hypothesis given a type I error of 0.05, a twofold minimum on colony morphology and color, were con®rmed as C. jejuni by difference in sample groups, and the number of samples analyzed PCR assay (25). for each pathogen. All analyses were performed using SAS for Salmonella was isolated from feces by inoculation of a 10-g Windows, version 8.0 (SAS Institute, Cary, N.C.). fecal aliquot into tetrathionate broth at a 1:10 dilution followed by incubation at 37ЊC for 48 h. One loopful (20 ␮l) of tetrathion- RESULTS ate broth enrichment was plated onto a xylose-lysine-tergitol-4 The ®rst 585 fecal samples collected were cultured for (XLT4) and incubated at 37ЊC overnight (16). From each XLT4 plate, up to three colonies with morphology typical of all three pathogens. An additional 101 samples were cul- were selected for biochemical screening (tri- tured for E. coli O157:H7 and Campylobacter. Three hun- ple iron, citrate, and urea agars). One colony from each dred forty additional samples were cultured for only E. coli sample that produced an acid butt and alkaline slant with H2S O157:H7. Salmonella was isolated from 39 of 585 (6.7%) production on triple sugar iron agar, was urea negative, and was samples, C. jejuni was isolated from 48 of 686 (7%) sam- citrate positive was serogrouped using group-speci®c antisera ples, and E. coli O157:H7 was isolated from 21 of 1,026 (Becton Dickinson, Sparks, Md.). (2.1%) samples. Of the 585 samples tested for all three All 1,026 samples were cultured for E. coli O157:H7. Ten pathogens, at least one pathogen was identi®ed in 86 of grams of feces from the primary samples was inoculated into 90 585 (15%) samples. One of the 21 samples positive for E. ml of Trypticase soy broth containing ce®xime (50 ng/ml) and coli O157:H7 also was positive for C. jejuni. Five of the vancomycin (40 ␮g/ml) (21). Samples were enriched for 18 to 24 48 samples positive for C. jejuni also yielded Salmonella. hat37ЊC prior to concentration of E. coli O157:H7 using im- munomagnetic separation following the manufacturer's recom- None of the 39 samples positive for Salmonella were pos- mendations for automated bead retrieval using the BeadRetriever itive for E. coli O157:H7. (Dynal, Oslo, Norway). Samples of uninoculated medium were Among the 936 of the 1,026 (91%) samples from tested on each day for cross-contamination in the bead washing which owner information was available, 475 different farms and separation steps. Beads were plated on MacConkey were represented. Size of herd of origin could be traced for agar plates containing ce®xime (50 ␮g/ml) and tellurite (100 ␮g/ 488 of 585 samples tested for Salmonella, 516 of 686 sam- ml) (SMACct). Up to ®ve suspect (sorbitol-negative) colonies re- ples tested for Campylobacter, and 916 of 1,026 samples covered from each SMACct plate were further screened for the tested for E. coli O157:H7. Herd size ranged from 1 to biochemical characteristics of E. coli O157:H7, including lactose 1,000 lactating cows, with an average of 110 and a median ␤ fermentation, absence of D-umbelliferyl- -glucuronide cleavage, of 60 lactating cows per herd. Individual farms sold be- and agglutination in a commercially available latex test kit speci®c tween 1 and 21 cattle during the course of the study, with for the O157 antigen (Oxoid, Ogdensburg, N.Y.). Isolates were 295 of 475 (62%) farms selling only 1 cow each. con®rmed as E. coli O157:H7 using a multiplex PCR assay (6). The frequency of recovery of Salmonella, Campylo- Determination of antibiotic resistance. Pure cultures of all bacter, and E. coli O157:H7 as classi®ed by herd size are pathogens isolated were frozen at Ϫ70ЊC in 30% buffered glycerol outlined in Table 1. Only Salmonella prevalence was sig- solution and tested for antibiotic resistance phenotype at a later ni®cantly different between large and small herds. Many C. date. E. coli O157:H7 and Salmonella isolates were tested for jejuni isolates were nonviable after long-term storage and susceptibility to amikacin, amoxicillin-clavulanic acid, ampicillin, were not available for antimicrobial resistance testing. The apramycin, cefoxitin, ceftriaxone, cephalothin, chloramphenicol, antimicrobial susceptibility phenotypes of recov- gentamicin, kanamycin, streptomycin, tetracycline, - ered in this study are reported in Table 2. sulfamethoxazole, sul®soxazole, , and cipro¯oxacin Postexperiment power analysis indicated that given the using the Kirby-Bauer disc diffusion method outlined by the Clin- observed prevalence, number of samples collected, and a ical and Laboratory Standards Institute (formerly NCCLS) (18). Ϫ␤ Campylobacter jejuni isolates were screened for susceptibility to type I error of 0.05, the statistical power (1 ) of the chloramphenicol, cipro¯oxacin, nalidixic acid, tetracycline, clin- experiment to detect a twofold difference in prevalence be- damycin, and according to the disc diffusion method tween the two groups was 0.90. Posttest power analysis of described by Sato et al. (22). The zones of inhibition were mea- the E. coli O157:H7 data yielded a power of 85% to detect sured and isolates were classi®ed as either resistant or susceptible a twofold increase in prevalence in this population. J. Food Prot., Vol. 68, No. 5 FOODBORNE PATHOGENS IN CULL DAIRY CATTLE 929

TABLE 1. Prevalence of foodborne pathogens in the feces of cull type, and variability in recent transport were eliminated. It dairy cattle at marketa is not know whether these pathogen prevalences are higher Prevalence by pathogen or lower than those observed if samples had been obtained on the farm prior to shipping or at the slaughterhouse gate Prevalence Salmonella C. jejuni E. coli O157:H7 immediately before slaughter. The sensitivity of detection for each of the speci®c pathogens in bovine feces also may Overall 39/580 (6.7) 50/688 (7.3) 21/1,026 (2.0) Large herds 21/223 (9.4) 21/271 (7.8) 8/382 (2.1) differ among pathogens. Small herds 7/203 (3.4) 19/245 (7.8) 6/387 (1.6) Reports of Campylobacter prevalence in dairy cattle Unknown size 11/154 (7.1) 10/172 (5.8) 7/257 (2.7) are limited, especially for cull cattle. Campylobacter prev- P value 0.018 1.00 0.602 alence is highest in young dairy cattle and lower in adult animals (5). Fecal excretion of C. jejuni is intermittent, and a Values are no. of positive samples/no. of samples tested (% pos- the magnitude of excretion by dairy cattle has a seasonal Ն Ͻ itive). Large herds had 60 cattle; small herds had 60 cattle. pattern (23, 24). Only Wesley et al. (30) speci®cally re- P values are for comparison between large and small herds. Downloaded from http://meridian.allenpress.com/jfp/article-pdf/68/5/927/1670153/0362-028x-68_5_927.pdf by guest on 26 September 2021 ported the prevalence of C. jejuni in cull dairy cattle. At the animal level (including lactating cows and cull cows on DISCUSSION farms), C. jejuni was more often recovered from animals In this study, approximately one of every six cull dairy (lactating cows and those expected to be culled in the next cattle destined for slaughter carried one or more genera of 7 days) originating from herds with more than 100 milk foodborne bacteria. Some animals were coinfected with C. cows than herds with fewer than 100 cows. Prevalence jejuni and either Salmonella or E. coli O157:H7. Together, among milk cows (43%) was higher than among cows at E. coli O157:H7, Salmonella, and Campylobacter account market (30%). However in the study reported by Wesley et for the majority of all diagnosed bacterial causes of food- al., samples were not collected from cattle expected to be borne in the United States (2). Foods of bo- culled from farms with fewer than 100 cows, and the size vine origin are a commonly implicated as vehicles for out- of herd of origin of cattle at market was not determined. breaks caused by these organisms (27). Given that fecal Thus, it was not possible to assess the effect of herd size prevalence of bacterial pathogens is correlated with carcass on prevalence of Campylobacter speci®cally among cattle contamination at slaughter, these animals serve as an im- expected to be marketed (30). Conversely, Sato et al. (22) portant entry point of these pathogens into the food chain found that the Campylobacter prevalence among cows and (3). calves was higher on smaller farms, but the range in herd Because of differences in microbiological culture sizes among the 60 herds studied was not provided. Sig- methods and sampling protocols, caution should be used ni®cant differences in C. jejuni prevalence in animals culled when comparing prevalences between studies. This study from large and small herds were not detected in the present differed from most previous studies because the cull dairy study. Based on the power analyses, any in¯uence of herd cattle (i) were from a large number of farms (Ͼ475), (ii) size on C. jejuni prevalence among cull dairy cattle was originated from a limited geographic area (most farms were minimal in the sample population tested. Although the within a 37-km radius of the auction market), and (iii) were prevalence of Salmonella-positive samples was slightly shipped during a limited time frame, and because the study higher among samples positive for C. jejuni than among was concentrated on only cull cattle at market. Thus, the those negative for C. jejuni (12.8 versus 7.8%), this differ- confounding factors of geographic region, season, animal ence was not signi®cant (P ϭ 0.43). Larger studies are

TABLE 2. Distribution of antimicrobial susceptibility phenotypes of foodborne pathogens isolated from cull dairy cattle at market according to size of herd of origin No. of isolates

Farm size

Organism Phenotype Large Small Unknown Total

Salmonella Pansensitivea 19 7 9 35 Am, K, T, S, C, and G 1 1 S and G 2 2 T 1 1 E. coli O157:3H7 Pansensitivea 8 5 7 20 Am, AmC, Cf, and Fox 1 1 Campylobacter Pansensitiveb 8 10 7 25 T 5 6 11 a Antibiotics tested were amikacin, amoxicillin±clavulanic acid (AmC), ampicillin (Am), apramycin, cefoxitin (Fox), ceftriaxone, ceph- alothin (Cf), chloramphenicol (C), gentamicin (G), kanamycin (K), streptomycin (S), tetracycline (T), trimethoprim-sulfamethoxazole, sul®soxazole, nalidixic acid, and cipro¯oxacin. b Antibiotics tested were C, cipro¯oxacin, nalidixic acid, T, clindamycin, and erythromycin. 930 DODSON AND LEJEUNE J. Food Prot., Vol. 68, No. 5 needed to determine whether infection with one of these in which 34% of E. coli O157:H7 isolates obtained from organisms affects the likelihood of fecal carriage of one or cattle were resistant to one or more antibiotics (13). Groups more other foodborne pathogens. of slaughtered animals other than cull dairy cattle may con- Reported prevalences for Salmonella carriage among tribute more extensively to the pool of antibiotic-resistant cull dairy cattle vary widely. For example, reported Sal- in the food chain. Because of the small monella prevalence in market dairy cows ranges from 4 to number of antibiotic-resistant organisms recovered in this 54%, depending on geographic location and season (26, study, the statistical power to detect a herd size effect on 29). In a recent cull cattle study in Kentucky, a slightly increased antibiotic resistance among isolated pathogens lower prevalence of 2.17% of fecal samples positive for was low. Salmonella, but those samples had been previously frozen, This study provides valuable information on the food resulting in a possible underestimation of the true preva- safety risks that cull dairy animals contribute to the food lence. Consistent with previous reports among lactating chain. One or more of the three bacterial pathogens eval- cows (7, 29), herd size was signi®cantly associated with uated in this study were found in 15% of cull dairy cattle. Downloaded from http://meridian.allenpress.com/jfp/article-pdf/68/5/927/1670153/0362-028x-68_5_927.pdf by guest on 26 September 2021 Salmonella prevalence among cull cattle in the present However, these cattle do not appear to be a primary res- study. ervoir from which multidrug-resistant bacterial pathogens Reports of prevalence of E. coli O157:H7 speci®cally enter the food chain. The interaction of herd size and path- in cull cattle at auctions are also limited. The frequency of ogen prevalence was pathogen speci®c, being strong for isolation of E. coli O157:H7 in the present study was com- Salmonella but undetectable for E. coli O157:H7 and C. parable to that previously obtained on farms from cattle jejuni. These differences may re¯ect differences in the ep- intended for culling but prior to shipment (15, 28), from idemiology and ecology of these organisms on farms, thus cull cows at market (28), and from cull cows at the slaugh- underscoring the need for multiple different preharvest con- ter plant immediately prior to slaughter (12). trol strategies to control each of these pathogens. Because of the controversies surrounding large-scale agriculture, the impact of herd size on the prevalence of ACKNOWLEDGMENTS infectious disease in commercial livestock is of interest. We acknowledge the willing participation of the sales barns and all The empirical and theoretical evidence of herd size as a the individual farmers who made this study possible. Funding for this risk factor for swine diseases has been recently reviewed project was provided by state and federal funds appropriated to the Ohio (4). Many of these same principles may be applied to dairy Agricultural Research and Development Center (OARDC), the OARDC Research Enhancement Competitive Grant Program, and the Copland cattle. For example, introduction and transmission of path- Fund (Dodson) at the College of Wooster (Wooster, Ohio). ogens are expected to occur more frequently among larger groups of animals. However, herd size might also serve as REFERENCES a surrogate marker for particular management or environ- 1. Anderson, A. D., J. M. Nelson, S. Rossiter, and F. J. Angulo. 2003. mental variables. Kabagambe et al. (10) identi®ed several Public health consequences of use of antimicrobial agents in food management factors that were signi®cantly associated with animals in the United States. Microb. Drug Resist. 9:373±379. dairy herd size, including the method of manure removal 2. Anonymous. 2004. Preliminary FoodNet data on the incidence of (¯ush versus scraping) and feeding practices (cottonseed infection with pathogens transmitted commonly through foodÐse- lected sites, United States, 2003. Morb. Mortal. Wkly. Rep. 53:338± products and brewers' products). Herd size has been sig- 343. ni®cantly associated with bovine viral , Johne's dis- 3. Elder, R. O., J. E. Keen, G. R. Siragusa, G. A. Barkocy-Gallagher, ease, neosporosis, and tuberculosis (11, 14, 17, 19). Poten- M. Koohmaraie, and W. W. Laegreid. 2000. Correlation of tial management-related risk factors other than herd size enterohemorrhagic Escherichia coli O157 prevalence in feces, hides, were not evaluated in this study but remained constant on and carcasses of beef cattle during processing. Proc. Natl. Acad. Sci. USA 97:2999±3003. each farm regardless of the pathogen detected. Therefore, 4. Gardner, I. A., P. Willeberg, and J. Mousing. 2002. Empirical and the differences in the effects of herd size on the prevalence theoretical evidence for herd size as a risk factor for swine diseases. of Salmonella, Campylobacter, and E. coli O157:H7 can be Anim. Health Res. Rev. 3:43±55. attributed to differences in the biology of these particular 5. Giacoboni, G. I., K. Itoh, K. Hirayama, E. Takahashi, and T. Mit- pathogens, particular management factors that act differ- suoka. 1993. Comparison of fecal Campylobacter in calves and cattle of different ages and areas in Japan. J. Vet. Med. Sci. 55:555±559. entially on dissemination of these organisms on dairy 6. Hu, Y., Q. Zhang, and J. C. Meitzler. 1999. Rapid and sensitive farms, or both of these factors. The most effective inter- detection of Escherichia coli O157:H7 in bovine faeces by a mul- vention strategies for control of these three particular food- tiplex PCR. J. Appl. Microbiol. 87:867±876. borne bacteria on farms will probably be different and path- 7. Huston, C. L., T. E. Wittum, B. C. Love, and J. E. Keen. 2002. ogen speci®c. Prevalence of fecal shedding of Salmonella spp in dairy herds. J. Am. Vet. Med. Assoc. 220:645±649. With the exception of tetracycline resistance, which is 8. Huysmans, M. B., and J. D. Turnidge. 1997. Disc susceptibility test- common in C. jejuni isolates of bovine origin (22), very ing for thermophilic . Pathology 29:209±216. few antibiotic-resistant organisms were identi®ed in this 9. Jordan, D., S. A. McEwen, A. M. Lammerding, W. B. McNab, and study. Similar to results reported by et al. (29), less J. B. Wilson. 1999. Pre-slaughter control of Escherichia coli O157 than 12% of all Salmonella isolates were resistant to one in beef cattle: a simulation study. Prev. Vet. Med. 41:55±74. 10. Kabagambe, E. K., S. J. Wells, L. P. Garber, M. D. Salman, B. Wag- or more antibiotics tested. Most E. coli O157:H7 isolates ner, and P. J. Fedorka-Cray. 2000. Risk factors for fecal shedding of recovered in this study were sensitive to all antibiotics test- Salmonella in 91 US dairy herds in 1996. Prev. Vet. Med. 43:177± ed. This ®nding is in contrast to those of previous studies 194. J. Food Prot., Vol. 68, No. 5 FOODBORNE PATHOGENS IN CULL DAIRY CATTLE 931

11. Kaneene, J. B., C. S. Bruning-Fann, L. M. Granger, R. Miller, and 21. Sanderson, M. W., J. M. Gay, D. D. Hancock, C. C. Gay, L. K. Fox, B. A. Porter-Spalding. 2002. Environmental and farm management and T. E. Besser. 1995. Sensitivity of bacteriologic culture for de- factors associated with tuberculosis on cattle farms in northeastern tection of Escherichia coli O157:H7 in bovine feces. J. Clin. Micro- Michigan. J. Am. Vet. Med. Assoc. 221:837±842. biol. 33:2616±2619. 12. Mcdonough, P. L., C. A. Rossiter, R. B. Rebhun, S. M. Stehman, D. 22. Sato, K., P. C. Bartlett, J. B. Kaneene, and F. P. Downes. 2004. H. Lein, and S. J. Shin. 2000. Prevalence of Escherichia coli O157: Comparison of prevalence and antimicrobial susceptibilities of Cam- H7 from cull dairy cows in New York state and comparison of cul- pylobacter spp. isolates from organic and conventional dairy herds ture methods used during preharvest food safety investigations. J. in Wisconsin. Appl. Environ. Microbiol. 70:1442±1447. Clin. Microbiol. 38:318±322. 23. Stanley, K., and K. Jones. 2003. Cattle and sheep farms as reservoirs 13. Meng, J., S. Zhao, M. P. Doyle, and S. W. Joseph. 1998. Antibiotic of Campylobacter. J. Appl. Microbiol. 94(Suppl.):104S±113S. resistance of Escherichia coli O157:H7 and O157:NM isolated from 24. Stanley, K. N., J. S. Wallace, J. E. Currie, P. J. Diggle, and K. Jones. animals, food, and humans. J. Food Prot. 61:1511±1514. 1998. The seasonal variation of thermophilic campylobacters in beef 14. Mockeliuniene, V., A. Salomskas, R. Mockeliunas, and S. Petkevi- cattle, dairy cattle and calves. J. Appl. Microbiol. 85:472±480. cius. 2004. Prevalence and epidemiological features of bovine viral 25. Stucki, U., J. Frey, J. Nicolet, and A. P. Burnens. 1995. Identi®cation diarrhoea virus infection in Lithuania. Vet. Microbiol. 99:51±57. of Campylobacter jejuni on the basis of a species-speci®c gene that

15. Murinda, S. E., L. T. Nguyen, S. J. Ivey, B. E. Gillespie, R. A. encodes a membrane . J. Clin. Microbiol. 33:855±859. Downloaded from http://meridian.allenpress.com/jfp/article-pdf/68/5/927/1670153/0362-028x-68_5_927.pdf by guest on 26 September 2021 Almeida, F. A. Draughon, and S. P. Oliver. 2002. Prevalence and 26. Troutt, H. F., J. C. Galland, B. I. Osburn, R. L. Brewer, R. K. Braun, molecular characterization of Escherichia coli O157:H7 in bulk tank J. A. Schmitz, P. Sears, A. B. Childers, E. Richey, E. Mather, M. milk and fecal samples from cull cows: a 12-month survey of dairy Gibson, K. Murthy, and A. Hogue. 2001. Prevalence of Salmonella farms in east Tennessee. J. Food Prot. 65:752±759. spp in cull (market) dairy cows at slaughter. J. Am. Vet. Med. Assoc. 16. Murray, P., E. Baron, M. A. Pfaller, F. Tenover, and R. Yolken (ed.). 219:1212±1215. 27. Troutt, H. F., and B. I. Osburn. 1997. Meat from dairy cows: possible 1999. Manual of clinical microbiology, 7th ed. ASM Press, Wash- microbiological hazards and risks. Rev. Sci. Tech. Off. Int. Epizoot. ington, D.C. 16:405±414. 17. Muskens, J., A. R. Elbers, H. J. Van Weering, and J. P. Noordhuizen. 28. Wells, J. G., L. D. Shipman, K. D. Greene, E. G. Sowers, J. H. 2003. Herd management practices associated with paratuberculosis Green, D. N. Cameron, F. P. Downes, M. L. Martin, P. M. Grif®n, seroprevalence in Dutch dairy herds. J. Vet. Med. B Infect. Dis. Vet. S. M. Ostroff, M. E. Potter, R. V. Tauxe, and I. K. Wachsmuthand. Public Health 50:372±377. 1991. Isolation of Escherichia coli serotype O157:H7 and other Shi- 18. NCCLS. 2003. Performance standards for antimicrobial disk suscep- ga-like -producing E. coli from dairy cattle. J. Clin. Microbiol. tibility tests. Approved standard M2-A8. NCCLS, Wayne, Pa. 29:985±989. 19. Otranto, D., A. Llazari, G. Testini, D. Traversa, A. Frangipane Di 29. Wells, S. J., P. J. Fedorka-Cray, D. A. Dargatz, K. Ferris, and A. Regalbono, M. Badan, and G. Capelli. 2003. Seroprevalence and Green. 2001. Fecal shedding of Salmonella spp. by dairy cows on associated risk factors of neosporosis in beef and dairy cattle in Italy. farm and at cull cow markets. J. Food Prot. 64:3±11. Vet. Parasitol. 118:7±18. 30. Wesley, I. V., S. J. Wells, K. M. Harmon, A. Green, L. Schroeder- 20. Rubin, S. J., and M. Woodard. 1983. Enhanced isolation of Cam- Tucker, M. Glover, and I. Siddique. 2000. Fecal shedding of Cam- pylobacter jejuni by cold enrichment in Campy-Thio broth. J. Clin. pylobacter and spp. in dairy cattle. Appl. Environ. Mi- Microbiol. 18:1008±1010. crobiol. 66:1994±2000.