Prevalence of Campylobacter and Salmonella Species on Farm, After Transport, and at Processing in Specialty Market Poultry

Prevalence of Campylobacter and Salmonella Species on Farm, After Transport, and at Processing in Specialty Market Poultry B. A. McCrea,†,1,2 K. H. Tonooka,* C. VanWorth,* C. L. Boggs, E. R. Atwill,* and J. S. Schrader‡ †Poultry Science Department, Auburn University, Auburn, Alabama 36849-5416; *Departments of Population, Health and Reproduction and Veterinary Extension, Veterinary Medicine Teaching and Research Center, University of California-Davis, 18830 Road 112, Tulare, California 93274; and ‡Scherring-Plough Animal Health, Elkhorn, Nebraska 68022 alence of positive chickens was found after 6 to 8 h holding before processing. In most cases, the prevalence of Campylobacter- and Salmonella-positive birds was lower on the final product than on-farm or during processing. Odds ratio analysis indicated that the risk of a positive final product carcass was not increased by the prevalence of a positive sample at an upstream point in the processing line, or by on-farm prevalence (i.e., none of the common sampling stations among the 6 commodities could be acknowledged as critical control points). This suggests that hazard analysis critical control point plans for Campylobacter and Salmonella control in the niche-market poultry commodities will need to be specifically determined for each species and each processing facility.

Key words: food safety, specialty market poultry, processing, Campylobacter jejuni, Salmonella 2006 Poultry Science 85:136–143

different management practices, processing techniques, and access to veterinary care and resources, may be largely irrelevant. Campylobacter and Salmonella are the 2 leading sources of food-borne illness in the US. A strong association has been demonstrated between the consumption of poultry products and sporadic outbreaks of bacterial gastrointestinal disease caused by Campylobacter spp. and Salmonella spp. in humans (Gast, 1997; Shane, 1997). Hazard analysis critical control point (HACCP) programs for food processing have been initiated in poultry processing plants to reduce the risk of food-borne illness. In addition, lowering the on-farm prevalence of bacteria that are potential food pathogens has been suggested as an important strategy for reducing the contamination of birds entering the processing plant and lowering the risk of contaminated meat products entering the food chain. Much of the current food safety research has focused on the broiler chicken. Critical control points (CCP) identified as potentially important for transmission of Campylobacter and Salmonella to chicken products include the infection status of the host population, fecal contamination during transport to the processing facility, and cross-contamination between carcasses and equipment during processing.

INTRODUCTION Very little is known about food safety risk factors for specialty poultry products, yet millions of pounds of these products enter the human food chain annually through local markets, US markets, and international markets. Specialty poultry products include squab (young pigeon), duckling, quail, poussin (young chicken), guinea fowl, and free-range chickens. Niche-marketing of specialty poultry products is being utilized by small farmers to supplement current or to develop new agricultural businesses. Specialty food areas that address the growing consumer preference for organic and natural products are growing in popularity in the United States. However, there is a complete lack of species-specific data concerning the prevalence and origin of microbial pathogens within these commodities. Deriving food safety recommendations from larger industries, with

2006 Poultry Science Association, Inc. Received May 26, 2005. Accepted September 18, 2005. 1 Corresponding author: [email protected] 2 Current address: Department of Animal Science, University of California-Davis, One Shields Ave., Davis, CA 95616.

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ABSTRACT The prevalence of Campylobacter and Salmonella spp. was determined from live bird to prepackaged carcass for 3 flocks from each of 6 types of California niche-market poultry. Commodities sampled included squab, quail, guinea fowl, duck, poussin (young chicken), and free-range broiler chickens. Campylobacter on-farm prevalence was lowest for squab, followed by guinea fowl, duck, quail, and free-range chickens. Poussin had the highest prevalence of Campylobacter. No Salmonella was isolated from guinea fowl or quail flocks. A few positive samples were observed in duck and squab, predominately of S. Typhimurium. Free-range and poussin chickens had the highest prevalence of Salmonella. Posttransport prevalence was not significantly higher than on-farm, except in free-range flocks, where a higher prev-

CAMPYLOBACTER AND SALMONELLA IN SPECIALTY POULTRY

MATERIALS AND METHODS Farm and Processing Plant Description Three flocks from 6 specialty types of poultry were sampled on farm, after transport, and at processing. Squab originated from 3 different farms with each batch or flock consisting of market-age squab (28 d-old) from multiple lofts on the farm. The 3 poussin flocks were reared in different conventional broiler houses on the same farm and marketed at 28 d of age. Duck flocks were from 2

geographically different farms; flocks 1 and 2 were from different houses on the same farm. Ducks were marketed between 69 and 84 d of age. Guinea fowl were also from 2 separate farms; 2 flocks came from the same farm, and were processed at 73 d of age. Quail were reared in progressive cage systems in which market-age birds (30 d) were removed from one end of a row and new chicks were placed at the opposite end. The 3 flocks in this study were from 3 separate cage rows on one farm. Free-range broilers were reared in conventional broiler houses modified to allow access to an outdoor yard. The 3 flocks sampled came from 3 contract ranches at different locations. The 3 processing plants were federally inspected. Plant A processed squab, poussin, and quail; plant B processed duck and guinea fowl; and plant C processed free-range chickens. Sampling stations common to all flocks were farm, post-transport (PT), picker, and prepackage. The other 2 to 3 stations in the processing plant varied by commodity (Table 1).

Sampling Methods All testing occurred during the summer months. The numbers of samples taken at the farm, PT, and within the processing plant were determined by estimating the prevalence of Campylobacter spp. in each group. A minimum of 40 samples and a maximum of 80 were obtained per station. Forty samples were obtained when previous studies indicated that the prevalence was high in the species. Forty samples per station were taken for species expected to have a high (>70%) prevalence of bacteria, 60 for medium (30 to 70%), and 80 for low prevalence species (<30%). Free-range and poussin were examples of high prevalence (Blaser, 1982; Marinescu et al., 1987; Mead et al., 1995; Gregory et al., 1997; Mead, 2004). Eighty samples were obtained when the prevalence was low for bacteria or if no information was available for the species. Squab was an example of low prevalence (Jeffrey et al., 2001a,b). No information on quail production and pathogens was available at the time of the study, so we chose to use the maximum number of samples to gather as much information as possible. An intermediate number of 60 samples was collected when the management system on the farm, or the processing methods, was similar to broiler production. Duck and guinea fowl were examples of intermediate prevalence (Kasrazadeh and Genigeorgis, 1987; Adekeye et al., 1989). Fecal samples were obtained at the farm and PT by cloacal swab using sterile cotton-tipped swabs. Drag swab cultures for both Salmonella and Campylobacter were taken from the floor of the loft, pen, house, or cage, from the floor of the transport crates, and from processing equipment at each station. On-farm sampling took place as transport crates were filled. Two fecal swab samples were taken from each bird; one was placed into semisolid enrichment media for Campylobacter culture (Jeffrey et al., 2000b) and the other into 0.5 mL of 2× skim milk (product no. 232100, Difco Laboratories, Detroit, MI) in 5-mL snap-top tubes for Salmonella culture. Crates were marked for identification, loaded

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Infection status of the host population can be an important factor in the contamination status of the final food products. Broiler flocks that tested negative at the farm for Campylobacter also tested negative after slaughter (Aho and Hirn, 1988). Age-dependent susceptibility to pathogens is an important determinant in the colonization status of the host. Young chickens (<2 wk) are extremely susceptible to infection by Salmonella spp. In contrast, colonization by Campylobacter spp. appears to be most common in broiler chickens >2 wk of age (Neill et al., 1984). Transport of broilers to the processing plant was shown to increase the prevalence of birds positive for Salmonella and Campylobacter because of fecal contamination of skin and feathers by neighboring birds during shipping (Stern et al., 1995). Prolonged crating was identified by Rigby and Pettit (1980) as a contributor to the contamination of processed broiler carcasses. Processing has been shown to increase contamination by Salmonella and Campylobacter in studies comparing on-farm prevalence to final product prevalence (Wempe et al., 1982; Oosterom et al., 1983; Mead et al., 1994). Others have established that an increase in microbial contamination of broiler chicken skin occurs during crating, transport, and processing (Rigby and Pettit, 1980; Stern et al., 1995; Carraminana et al., 1997). Conversely, some researchers have observed a decline in pathogen loads during processing. Mead et al. (1995) found a 100-fold decline in Campylobacter prevalence on neck skin following processing. A reduction of Enterobacteriaceae was described by Lillard and Ang (1989) when comparing pre- and postevisceration breast skin samples. Salmonella however, persisted at high levels on carcasses because of firm attachment to poultry skin (Lillard and Ang, 1989). A processing plantdependent isolation rate of Campylobacter on carcasses and equipment has been reported (Izat et al., 1988). The published prevalence of positive Campylobacter isolations from commercial broiler carcasses ranges from 0 to 100% (Blaser, 1982). A reported prevalence of Campylobacter-positive duck carcasses was 6.7% (Kasrazadeh and Genigeorgis, 1987). Salmonella has been found at prevalences of 0 to 36.5% on chicken carcasses (Jacobs-Rietsma et al., 1994; Uyttendaele et al., 1999). The objective of this study was to define the incidence of the food-borne pathogens Campylobacter and Salmonella throughout the continuum from farm to final product in order to identify potential CCP for microbial contamination that could be incorporated into commodity-specific HACCP plans for ensuring food safety.

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MCCREA ET AL. Table 1. Mean prevalence of Campylobacter-positive skin swabs in 6 specialty poultry commodities by sampling station Commodity Sampling station 1

Post-transport Post-transport 21 Postpicker4 Postcrop4 Postfeet removal4 Postwax4 Post-trachea removal4 Prewash4 Postevisceration4 Post-in/out bird wash4 Prepackaging4

Squab

Poussin

3% ± 3 NA3 1% ± 0.9 2% ± 1 NA NA NA NA 4% ± 3 NA 0.3% ± 0.3 2

80% ± NA 2% ± NA 2% ± NA NA NA 4% ± NA 24% ±

10 1 2

3 21

Duck 33% ± NA 26% ± NA NA 7% ± NA NA 14% ± NA 3% ±

Guinea 24 24 7 14 3

7% ± NA 50% ± NA NA NA 55% ± NA 57% ± NA 4% ±

5 6

9 4 2

Quail

Free-range

20% ± 10 NA 22% ± 0.9 1% ± 0.9 NA NA NA NA 18% ± 7 0.3% ± 0.35 2% ± 1

51% ± 13 80% ± 4 100% NA NA NA NA 99% ± 0.7 100% 77% ± 15 2% ± 2

1

Cloacal swab. Mean ± SE. 3 NA = not applicable. 4 Carcass swab. 5 This postwash station is not an in/out bird washer as it is in free-range. For quail, it involved a rinse wash. 2

fowl, quail, and 1 of 3 of duck flocks, swabs were placed in 0.5 mL of phosphate-buffered saline in 5-mL snap-top tubes for transport to the laboratory.

Laboratory Processing, Culture, and Identification Samples were transported to the laboratory and placed at 4°C. Campylobacter were identified by colony morphology, followed by oxidase and catalase tests and gram stain. Identification of Salmonella for squab, poussin, and duck was performed by the California Animal Health and Food Safety Laboratory and in our laboratory for quail, guinea fowl, and free-range chickens using identical methods. Each sample was added to 5 mL of tetrathionate broth (Product no. 210430, Difco Laboratories, Detroit, MI) and incubated 8 to 12 h at 37°C, then plated to xylose lysine tergitol-4 (Product no. 110463, Remel, Inc., Lenexa, KS) and

Table 2. Recovery of Salmonella isolates from 6 niche market poultry commodities sampled on the farm, after transport, and during processing Commodity Sampling station On-farm1 Post-transport1 Post-transport 21 Postpicker4 Postcrop4 Postfoot removal4 Postwax4 Post-trachea removal4 Prewash4 Postevisceration4 Post-In/Out bird wash4 Prepackaging4 1

Squab 1.3% ± 0.72 2.1% ± 0.9 NA3 23.8% ± 2.8 6.3% ± 1.6 NA NA NA NA 2.9% ± 1.1 NA 11.7% ± 2.1

Poussin 15.8% ± 13.3% ± NA 23.3% ± NA 13.3% ± NA NA NA 12.5% ± NA 17.5% ±

3.3 3.1 3.9 3.1

3.0 3.5

Duck 3.3% ± 3.3% ± NA 6.1% ± NA NA 11.3% ± NA NA 0% NA 0%

1.3 1.3 1.8 2.0

Guinea fowl

Quail

0% 0% NA 0.6% ± 0.6 NA NA NA 0% NA 0% NA 0%

0% 0% NA 4.6% ± 1.4 0% NA NA NA NA 0% 0%5 0%

Free-range 11.1% ± 9.4% ± 12.2% ± 75.6% ± NA NA NA NA 43.9% ± 47.8% ± 18.3% ± 6.1% ±

2.3 2.2 2.4 3.2

3.7 3.7 2.9 1.8

Cloacal swab. Mean ± SE. 3 NA = not applicable. 4 Carcass swab. 5 This postwash station is not an in/out bird washer as it is in free-range. For quail, it involved a rinse wash. 2

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on the truck, and driven to the processing facility. Posttransport sampling occurred immediately after the marked crates were unloaded at the processing plant. Samples were obtained by cloacal swab, and the birds were returned to crates for processing. In free-range chickens, a second PT (PT2) sampling was performed just before processing, after the birds had been held at the plant for 6 to 8 h. Processing plant samples were obtained by swabbing the skin of the carcass along the length of the body, avoiding the cloacal area. Core sampling stations for all groups were the picker, postevisceration, and at prepackaging. The other stations varied by species and commodity (Table 1). Each skin swab was placed into its respective media and capped, and the process was repeated until the required number of swabs was taken for each station. For squab, poussin, and 2 of 3 duck flocks, semisolid media was used for enrichment and transport of samples collected in the processing plant. For free-range chickens, guinea

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Table 3. Odds ratios of a carcass being positive at prepackage (last stage of processing) given it was positive at a prior processing station1

Campylobacter

Salmonella

Prepackage

Evisceration

Picker

PT

On-farm

— — — — — — — —

1.17 — — — 1.05 — — —

1.17 1.06 — — 1.012 1.07 — —

1.06 1.04 0.98 — 1.422 1.29 1.16 —

1.06 1.05 0.992 0.972 1.10 1.22 1.10 1.15

1

Only stations common to the 6 commodities were included in the analysis. 2 Not significant.

Statistical Data Data collected from sampling stations that were common to all 6 commodities were evaluated by block logistic regression to test the influence of each processing step on the prevalence of Campylobacter and Salmonella on the final product. This analysis generated the odds ratio for being positive at the prepackaging (final) site, given a bird that was positive at a previous sampling station. Logistic regression analysis was performed for the number of birds contaminated with Campylobacter to see if the flock sampled was significantly associated with an increased level of bacterial contamination. Logistic regression analysis was also used to determine if there was a significant difference between the number of birds contaminated with Campylobacter before transport (farm), immediately after transport (PT), and an additional 8 h later (PT2; SPSS, 2003).

RESULTS The prevalence of Campylobacter (Table 1) and Salmonella (Table 2) among the 6 commodities was highly variable. Spikes in the prevalence of positive birds for both Campylobacter and Salmonella during processing were observed; however, these increases were not consistent across commodities or within a processing plant. Odds ratios for the 6 commodities combined into a common statistical analysis across the 5 stations similar to all processing methods were generated (Table 3).

Squab For Campylobacter, on-farm prevalence was lowest for squab (10%, 0, and 0; Figure 1). For Salmonella, there were

Figure 1. On-farm prevalence (%) of Campylobacter for the 3 flocks of squab, poussin, and ducks.

a few positive samples and one completely negative farm. Serotypes at the farm were predominantly S. Typhimurium. Drag swabs from one of the squab farms were further identified as S. Seftenberg. Only one flock on the farm was positive for Campylobacter, and those numbers decreased PT. Salmonella increased PT (from 1 to 2, and 2 to 3 positive samples) in 2 of 3 flocks. The third flock was negative for Salmonella. In the processing plant, the second flock was 34% positive for Salmonella. S. Typhimurium was identified in flock 1 from the farm to the final product. S. Typhimurium was the predominant Salmonella isolated from flock 2 with S. Infantis on the drag swab at prepackaging. S. Heidelberg and S. Typhimurium were observed in low numbers in flock 3, and no Salmonella were recovered on the final product (Table 4).

Poussin Poussin demonstrated the highest Campylobacter prevalence (80%, 97%, and 80%) among the 6 commodities tested from on-farm samples (Figure 1). Poussin also had the highest prevalence for Salmonella (23%, 8%, and 18%) from on-farm samples. In addition to the serotypes identified from individual poussin on-farm, drag swabs of the houses yielded S. Kentucky and S. Agona. Prevalence of Campylobacter-positive poussin was the same pretransport and PT in one flock, higher by one positive sample in the second flock, and lower in the third flock. Salmonella decreased PT in 2 poussin flocks and increased in the third flock. Serotypes identified PT in drag swabs and individual poussin were S. Infantis in flock 1 and S. Kentucky in flocks 2 and 3. In the processing plant, flock 1 showed an overall prevalence of ≤10% for samples positive for Salmonella or Campylobacter on the final prepackaged product. Exceptionally higher rates were noted in flock 2, in which 67% were positive for Campylobacter, and in flock 3, in which 52% of

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hektoen enteric (Product no. 221365, Difco Laboratories, Detroit, MI) with novabiocin (Product no. 155957, ICN Biomedicals, Inc., Aurora, OH) for Salmonella identification. Suspect colonies were transferred to blood and MacConkey plates and incubated for 24 h at 37°C. Suspect colonies were further tested by reactions in triple sugar iron and urea slants and were positively confirmed as Salmonella with polyclonal antisera. Ten percent of positives from all stations were submitted for serotyping (Veterinary Medicine Teaching & Research Center, Tulare, CA).

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Table 4. Prevalence of Salmonella spp. isolated in 3 flocks sampled from each of 6 specialty market commodities1 Squab

On-farm Post-transport Post-transport 2 Postpicker Postcrop Postfeet removal Postwax Post-trachea removal Prewash Postevisceration Post-in/out bird wash Prepackaging

Poussin

Duck

Guinea fowl

Cloacal/ carcass swab

Drag swab

Cloacal/ carcass swab

Drag swab

Cloacal/ carcass swab

Drag swab

Cloacal/ carcass swab

Drag swab

A,O A — A, E, U A — — — — A — A

A A, B, C, U — — — — — — — — — —

B, C, H B, C — B, C, E, H, I — B, C — — — B, C, H — C

B, C C, H — C, I — — — — — — — —

A A — D, E, O — — A, F, O — — — — —

E A, D, E — A — — — — — — — —

— — — A — — — — — — — —

— — — U — — — — — — — —

Quail Cloacal/ carcass swab — — — G, O — — — — — — —

Free-range Drag swab

Cloacal/ carcass swab

Drag swab

— E, G — — — — — — — — — —

G, H G, H G, H G, H G, H — — — A, G G, H G, H G

G G, H G, H H G — — — — — G G, H

1 A–Salmonella Typhimurium, B–S. Infantis, C–S. Kentucky, D–S. Seftenberg, E–S. Heidelberg, F–S. Cerro var O14+, G–S. Hadar, H–S. Montevideo, I–S. Agona, O–rough O, and U–untypeable.

Duck Ducks ranked fourth in Campylobacter prevalence on the farm among the 6 commodities tested (Figure 1). There were less than 10 Salmonella-positive samples on the farm, and 1 flock was completely negative for the organism. Serotypes identified at the farm were predominately S. Typhimurium (Table 4). Campylobacter recovery increased from 60% on the farm to 80% PT in flock 3 (Figure 2). The Salmonella prevalence was similar for all flocks (data not shown). Concurrent with S. Typhimurium isolation from cloacal swabs on-farm; S. Heidelberg was isolated from drag swabs on-farm, and S. Seftenberg was isolated from drag swabs from crates PT (Table 4). In the processing plant, the prevalence of Campylobacter- or Salmonella-positive samples from the prepackaged product for each flock was ≤10%. Salmonella species recovered at processing included S. Seftenberg, S. Typhimurium, S. Heidelberg, S. Siegburg, and some untypeable isolates (Table 4).

Guinea Fowl Guinea fowl ranked fifth among the 6 commodities in onfarm Campylobacter prevalence (Figure 3). No Salmonella were isolated from any of the 3 flocks on-farm. The prevalence of Campylobacter decreased between on-farm and PT sampling for all 3 flocks but remained similar for Salmonella. In the processing plant, the prevalence of Campylobacter- or Salmonella-positive samples from the prepackaged product for each flock was ≤10%. A single isolate of Salmonella cultured at the picker station was serotyped as S. Typhimurium (Table 4).

Quail Quail ranked third among the 6 commodities in on-farm Campylobacter prevalence (Figure 3). No Salmonella was iso-

lated from the 3 flocks at the farm. The prevalence of Campylobacter decreased between on-farm and PT sampling but remained the same for Salmonella. Although no individual quail were positive for Salmonella PT, drag swabs from crates in all 3 flocks were positive. Serotypes recovered from crates were S. Heidelberg and S. Hadar. In the processing plant, the prevalence of Campylobacter- or Salmonella-positive samples from the prepackaged product for each flock was ≤10%. The 2 Salmonella serotyped from the picker station were S. Hadar and an untypeable isolate (Table 4).

Free-Range Chickens Free-range chickens ranked second among the 6 commodities for on-farm Campylobacter (Figure 3). Free-range chickens also ranked second for Salmonella prevalence onfarm (22%, 0, and 12%). In all free-range flocks, PT2 sampling of chickens within the same crates yielded a higher prevalence of Campylobacter-positive cloacal swabs (32 vs. 87%, 68 vs. 80%, 55 vs. 72%; n = 40). Although there were no differences in Campylobacter prevalence between samples taken on-farm and those samples taken immediately PT, there was a significant increase in the percentage of positive samples taken after the 6 to 8 hour holding period before processing (PT2) (Figure 4). In the processing plant, the prevalence of Campylobacter- or Salmonella-positive samples from the prepackaged product for each flock was ≤10%. In all free-range flocks, the 2 predominant serotypes of Salmonella isolated were S. Hadar and S. Montevideo (Table 4).

DISCUSSION The overall prevalence of Campylobacter and Salmonella among the 6 commodities at the farm varied considerably. Squab had very low prevalences of Campylobacter spp. at all 3 farms (10, 0, and 0%). Salmonella spp. prevalence was lower among squab than the other commodities at 1.2, 2.5, and 0%. The low on-farm prevalence of these bacteria in squab was consistent with our earlier work (Jeffrey et al.,

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samples were positive for Salmonella at the prepackage station. S. Kentucky was the only serotype found in flock 3 at prepackage. Serotypes isolated are listed in Table 4.

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Figure 2. Panel A. Variation in prevalence (%) of Campylobacter from the farm through the picker in 3 duck flocks. Panel B. Variation in prevalence (%) of Campylobacter from postwax through to the finished product in 3 duck flocks.

2001). Prevalence results from duck sampling did not agree with previously published reports. Kasrazadeh and Genigeorgis (1986) found 100% prevalence of C. jejuni in ducks sampled from 4 different brooder houses at 8 d of age, whereas we found the prevalence of Campylobacter spp. in ducks 69 to 84 d of age was much lower, 27, 2.5, and 60%. Although in broiler chickens, once a flock became positive they were usually positive at market age (Pokamunski et al., 1986), laying hens were reported to eventually clear Campylobacter infection (by 1 yr; Doyle, 1984). The influence of age on Campylobacter carriage in ducks requires further study. Campylobacter prevalence ranged from 5 to 25% in guinea fowl flocks and from 14 to 41% in quail flocks. No Salmonella was isolated from either species. The similarity of these results was not due to similar management or environment. Guinea fowl were raised on litter in houses similar to broiler chickens and marketed at 73 d, whereas quail were grown in wire cages approximately 3 ft above the ground and marketed at 56 d of age. Poussin and freerange chickens were the 2 groups that had the highest

prevalence of Campylobacter-positive birds; poussin were 80 to 97% positive, and free-range chickens were 32 to 68% positive. The extremely high prevalence in poussin, with a market age of 28 days, agreed with a prospective epidemiologic study conducted in broilers of similar age. Pokamunski et al. (1986) reported on 3 flocks positive at 28 d of age, with 100% prevalence within a flock. Results for free-range flocks were consistent with other published studies. Heuer et al. (2001) found a mean prevalence of 64% Campylobacterpositive chickens in organic free-range flocks. Heuer et al. also noted that the organic free-range flocks had a higher prevalence of positive flocks (100%) than the conventional broiler flocks (36.7%). Rivoal et al. (1999) observed an 85.7% prevalence in one free-range flock in France. In a study of free-range chickens in Peru, the frequency of positive isolates was 54% (Tresierra-Ayala et al., 1995). Although free-

Figure 4. Average prevalence of Campylobacter in post-transport (PT) and post-transport 2 (PT2) samples of free-range chickens taken after a 6 to 8 h holding period on the transport vehicle (%, n = 40). a,bDifferent superscripts indicate a significant difference (P ≤ 0.05).

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Figure 3. On-farm prevalence (%) of Campylobacter for the 3 flocks of guinea fowl, quail, and free-range chickens.

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modate these differences while capturing data from core stations similar to all. When prevalences were combined across species for these core stations, odds ratio analysis failed to identify any of the core stations (PT, postpicker, postevisceration, prepackaging) as significant contributors to the bacterial status of the prepackaged carcass. This is an important finding because it supports commodityspecific HACCP, not generic HACCP plans for specialty poultry products. Squab, poussin, and quail were all processed in plant A, which did have a higher bacterial prevalence in the final product compared to plant B or C. In the same temporal period, plant A yielded positive Salmonella samples in squab on one occasion and positive Salmonella and Campylobacter samples in poussin on 2 occasions. A faulty chlorinator system in the chill water was discovered and replaced. Subsequently, quail were processed with no spikes in prevalence for either bacterium. Duck and guinea fowl were processed by plant B. The prevalence of Campylobacter positive ducks was very low except for the third flock, which had 74% positive at the picker, 26% at postwax, 52% at postevisceration, and 7.5% at the final product (Figure 2). This flock also had the highest on-farm Campylobacter prevalence, and Salmonella prevalence spiked at the postwax station (up to 32% from 10% at the previous station). No Salmonella were isolated from the final product. This may indicate a carry-over of on-farm bacteria into the plant or may suggest a point of contamination within the plant. Conversely, the duck flock with the lowest on-farm prevalence had the lowest prevalence on the prepackaged carcasses. All 3 free-range flocks had a high prevalence (up to 100% positive) for Campylobacter at all stations except prepackage, which was less than 10% positive. Salmonella increased dramatically after the picker, identifying this station as an important CCP for Salmonella in this commodity. For example, free-range flock 3 entered the picker with 0% prevalence and exited with 52% prevalence of positive samples. Reducing contamination at the picker is an area that needs further research. The inside-outside bird washer combined with 111 min in the chill tank was also identified as an important CCP for lowering contamination of the final product in this plant. There was a 47 to 90% reduction in Campylobacter and a 37 to 100% reduction in Salmonella following these 2 processing stations (data combined for all 3 flocks not shown). The lower the incoming prevalence of Campylobacter, the greater the observed effect of the inside-outside bird washer. The potential for the transmission of food safety pathogens to humans through specialty poultry products is real, and the prevalence of these pathogens in this study varied widely. Some species of birds appeared to have lower prevalences of both Campylobacter and Salmonella than others. The respective impacts of species-specific physiology and varying management practices on the bacteria-host relationship are not well understood at this time. With labor, time, and financial constraints, reducing bacterial pathogens on the farm and in the processing plant remain difficult tasks. The results of this study clearly demonstrate

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range chickens have access to outside soil and water, which could provide exposure to additional vectors of infection, we observed higher prevalences in the poussin flocks, which were reared in enclosed housing. Possible explanations are the effect of bird density and increased success of fecal-oral transmission, strain differences in the birds, immune status of the flocks, and strain differences among the Campylobacter isolated, in addition to the role of environmental factors. Seasonal differences in isolation rates for Campylobacter have been reported, with warmer summer months yielding higher prevalences (Annah-Prah and Janc, 1988; Jacobs-Reitsma et al., 1994; Willis and Murray, 1997; Perko-Makela et al., 2002). All poussin flocks were sampled in the hottest months of summer, whereas free-range sampling occurred later in the summer and further north where temperatures were slightly cooler. There may also be a cyclic pattern of shedding within flocks that was observed by Achen et al. (1986). Prevalence of Salmonella-positive birds in the 2 chicken commodities was variable by flock, ranging from 0 to 23%. Jacobs-Reitsma et al. (1994) reported 27% prevalence in Dutch flocks, and a report from Japan reported a 14% prevalence in 28 flocks (Limawongpranee et al., 1999). A report by the USDA in 1998 found a Salmonella prevalence of 7% in 80,000 chickens tested across the US. In contrast to Campylobacter, Salmonella does not show a seasonal effect (Jacobs-Reitsma et al., 1994). It must also be considered that our samples were collected in the summer months, and further research would elucidate any seasonal trends in the bacterial load on these commodities. Transport did not significantly increase prevalence of bacteria in any commodity except free-range chickens and then only for Campylobacter. The largest increase in positive swabs occurred at the PT2 sampling. The time between PT and PT2 for flock 1 was 8 h, for flock 2 was 6.5 h, and for flock 3 was 6 h. Prevalence of Campylobacter increased 27 to 87% in flock 1 from PT to PT2, 73 to 80% in flock 2, and 52 to 72% in flock 3. Whyte et al. (2001) examined the effect of distance and holding time on Campylobacter prevalence in broiler chickens and found that neither variable significantly affected Campylobacter excretion rates in those flocks studied (n = 10). This study involved a much larger sample size, and a definitive increase in prevalence was observed. The difference between our study and the previous report is that the wait time before slaughter was much higher than the reported mean of Whyte et al. of 113 min. Feed and water withdrawal are normally used to decrease fecal discharge during transport of broilers to the processing plant. As noted by Stern et al. (1995), this withdrawal, along with the stresses of transport, could affect levels of shedding. Further studies of holding time would have to confirm these preliminary results. Numerous researchers have reported that the processing of poultry makes the spread of bacterial contamination possible. Certain CCP are recognized as points of crosscontamination between carcasses or between carcasses and equipment, such as the feather picker and the chilling tank. In this study, each commodity had a slightly different processing format; therefore, sampling was arranged to accom-

CAMPYLOBACTER AND SALMONELLA IN SPECIALTY POULTRY

that CCP for reducing bacterial contamination are not the same across all species or commodities and suggest that HACCP plans for Campylobacter and Salmonella control may need to be specifically designed to accommodate these differences. Further examination of rearing and processing methods is needed to fully evaluate the CCP within individual commodities and to design control programs for assuring food safety.

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