Recovery of Escherichia coli Biotype I and Enterococcus spp. during refrigerated storage of beef carcasses inoculated with a fecal slurry.

Three beef front quarters/carcasses were inoculated with a slurry of cattle manure. During storage at 4 degrees C, two sponge samples from each of three sites (i.e., 100 cm2 from each of two fat surfaces and 100 cm2 from a lean surface) were taken from each of the three carcasses on days 0, 1, 3, 7, and 10 after inoculation. The initial numbers of Escherichia coli averaged 2.0 log10 CFU/cm2 (1.21 to 2.47 log10 CFU/cm2) using the Petrifilm method and 2.09 log10 most probable number (MPN)/cm2 (0.88 to 2.96 log10 MPN/cm2) using the MPN method. The initial numbers of enterococci averaged 3.34 log10 CFU/cm2 (3.07 to 3.79 log10 CFU/cm2) using kanamycin esculin azide agar. In general, an appreciable reduction in the numbers of E. coli occurred during the first 24 h of storage; for the Petrifilm method an average reduction of 1.37 log10 CFU/cm2 (0.69 to 1.71 log10 CFU/cm2) was observed, and for the MPN method an average reduction of 1.52 log10 MPN/cm2 (0.47 to 2.08 log10 MPN/cm2) was observed. E. coli were not detected (<-0.12 log10 CFU/cm2) using Petrifilm on day 7 of the storage period on two (initial counts of 1.21 and 2.29 log10 CFU/cm2) of the three carcasses. However, viable E. coli cells were recovered from these two carcasses after a 24-h enrichment at 37 degrees C in EC broth. Viable E. coli cells were detected at levels of -0.10 log10 CFU/cm2 on the third carcass (initial count of 2.47 log10 CFU/cm2) after 7 days at 4 degrees C. No significant difference in recovery of viable cells was observed between the MPN and Petrifilm methods on days 0, 1, and 3 (P > 0.05). However, viable E. coli cells were recovered from all three carcasses by the MPN method on day 7 at an average of -0.29 log10 MPN/ cm2 (-0.6 to -0.1 log10 MPN/cm2). On day 10, viable cells were recovered by the MPN method from two of the three carcasses at -0.63 and -0.48 log10 MPN/cm2 but were not recovered from the remaining carcass (<-0.8 log10 MPN/cm2). Similar to E. coli, the greatest reduction (average of 1.26 log10 CFU/cm2, range = 1.06 to 1.45 log10 CFU/cm2) in the numbers of enterococci occurred during the first 24 h of storage. Because of higher initial numbers and a slightly slower rate of decrease, the numbers of Enterococcus spp. were significantly higher (P < 0.017) than the numbers of E. coli Biotype I after 3, 7, and 10 days of storage. These results suggest that enterococci may be useful as an indicator of fecal contamination of beef carcasses.     

Comparison of the traditional three-tube most probable number method with the Petrifilm, SimPlate, BioSys optical, and Bactometer conductance methods for enumerating Escherichia coli from chicken carcasses and ground beef

A study was conducted to compare commonly used methods, such as Petrifilm and SimPlate, and the rapid microbiological methods BioSys optical and Bactometer conductance to the standard most probable number (MPN) procedure for enumerating Escherichia coli from poultry carcasses and ground beef. Broiler carcasses and ground beef were evaluated in each of three replicate trials. Five groups of carcasses or ground beef were sampled and analyzed using Petrifilm, SimPlate, BioSys optical, and Bactometer conductance measurements after temperature abuse at 37 degrees C for 0 (Petrifilm and SimPlate only), 2, 4, 6, or 8 h. The correlation coefficients for the regression lines comparing the standard E. coli MPN procedure to Petrifilm and SimPlate for chicken and ground beef, respectively, were as follows: 0.95, 0.94, 0.93, and 0.91. The correlation coefficients for the regression lines comparing the standard E. coli MPN procedure to BioSys optical and Bactometer conductance measurements for chicken and ground beef, respectively, were -0.91, -0.90, -0.93, and -0.96. Although Petrifilm and SimPlate performed well, E. coli could not be enumerated from 16.7 and 10% of samples, respectively, using these methods. The BioSys optical and Bactometer conductance methods performed very well when compared with Petrifilm and SimPlate. Using rapid methods (BioSys optical and Bactometer conductance), results were obtained in 1 to 11 h rather than the 48 h required to conduct Petrifilm or SimPlate or the 5 days required to conduct the MPN procedure. These methods may allow processors to test products and obtain results before shipping, avoiding the cost and loss of reputation associated with a recall or foodborne illness outbreak.     

Evaluation of the MPN, Anderson-Baird-Parker, Petrifilm E. coli and Fluorocult ECD method for enumeration of Escherichia coli in foods of animal origin.

Commercially available beta-D-glucuronidase (GUR) based methods, Petrifilm E. coli (PEC) and Fluorocult ECD (FECD), and ISO standard MPN and Anderson-Baird-Parker (ABP) procedures were evaluated for routine enumeration of E. coli in naturally contaminated foods of animal origin. The methods concerned were classifiable in a sequence of best qualities for: production, MPN > ABP = PEC = FECD; costs, FECD > ABP = PEC > MPN; time per measurement, ABP = PEC = FECD > MPN; practical use, PEC > FECD > ABP > MPN; detection at low contamination, MPN > ABP = PEC > FECD. The ABP and PEC method appeared useful for routine counting of E. coli in raw meat, poultry and meat products, whereas the MPN procedure turned out to be more sensitive, however, impractical and considerably more expensive. The FECD method was inexpensive although suitable for the enumeration of E. coli at higher contamination level (> 50 cfu/g). The indole and MUG indicators both applied to demonstrate E. coli with the ABP or FECD method proved to be equal in specificity.     

Comparison of an automated most-probable-number technique with traditional plating methods for estimating populations of total aerobes, coliforms, and Escherichia coli associated with freshly processed broiler chickens

An instrument (TEMPO) has been developed to automate the most-probable-number (MPN) technique and reduce the effort required to estimate some bacterial populations. We compared the automated MPN technique with traditional microbiological plating methods and Petrifilm methods for estimating the total viable count of aerobic microorganisms (TVC), total coliforms (CC), and Escherichia coli populations (EC) on freshly processed broiler chicken carcasses (postchill whole carcass rinse [WCR] samples) and cumulative drip-line samples from a commercial broiler processing facility. Overall, 120 broiler carcasses, 36 prechill drip-line samples, and 40 postchill drip-line samples were collected over 5 days (representing five individual flocks) and analyzed by the automated MPN and direct agar plating and Petrifilm methods. The TVC correlation coefficient between the automated MPN and traditional methods was very high (0.972) for the prechill drip samples, which had mean log-transformed values of 3.09 and 3.02, respectively. The TVC correlation coefficient was lower (0.710) for the postchill WCR samples, which had lower mean log values of 1.53 and 1.31, respectively. Correlations between the methods for the prechill CC and EC samples were 0.812 and 0.880, respectively. The estimated number of total aerobes was generally greater than the total number of coliforms or E. coli recovered for all sample types (P < 2e?1?). Significantly more bacteria were recovered from the prechill samples than from the postchill WCR or cumulative drip samples (P < 9.5e?12 and P < 2e?1?, respectively). When samples below the limit of detection were excluded, 92.1% of the total responses were within a single log difference between the traditional plating or Petrifilm methods and the automated MPN method.     

Microbiological status of Australian sheep meat.

Two studies were undertaken to determine the microbiological status of sheep carcass meat and frozen, bulk-packed sheep meat produced in Australia. Samples were collected from 470 sheep carcasses and 415 cartons of frozen sheep trimmings over a period of approximately 12 months. Samples were collected from plants processing sheep carcasses for domestic or export markets. On carcasses, where bacterial counts were obtained, the mean of the log10 aerobic plate count (APC) was 3.92/cm2, the geometric mean of the most probable number (MPN) per square centimeter of Escherichia coli (biotype I) was 23, and the geometric mean of the coliform count was 38 MPN per cm2. A high percentage (75%) of samples was positive for E. coli (biotype I), 81% were positive for coliforms, 5.74% were positive for Salmonella spp., and 1.29% were positive for Campylobacter. Bacterial counts were higher on carcasses chilled over a weekend than on carcasses chilled for 24 h. The total number of bacteria on carcasses processed for domestic markets was similar to that on carcasses processed for export markets. E. coli O157 was not isolated from any of the 465 samples tested. Of the frozen export samples that tested positive, the mean of the log10 APC was 3.47/g, the geometric mean of the E. coli (biotype I) count was 9 MPN per g, and the geometric mean of the coliform count was 19 MPN per g. Of the frozen export samples tested, 48% were positive for E. coli (biotype I), 58% were positive for coliforms, and 6.5% were positive for Salmonella spp. E. coli O157 was recovered from 1 of 343 frozen sheep meat samples tested (0.29%). Bacterial counts were higher on samples of domestic product than on samples of export product. Results from both surveys are compared with data from similar studies conducted in other countries.     

An investigation of Escherichia coli O157 contamination of cattle during slaughter at an abattoir

The extent of contamination with Escherichia coli O157 was determined for 100 cattle during slaughter. Samples from 25 consecutively slaughtered cattle from four unrelated groups were collected from the oral cavity, hide, rumen, feces after evisceration, and pre- and postchill carcass. Ten random fecal samples were collected from the pen where each group of animals was held at the abattoir. E. coli O157 was detected using automated immunomagnetic separation (AIMS), and cell counts were determined using a combination of most probable number (MPN) and AIMS. E. coli O157 was isolated from 87 (14%) of the 606 samples collected, including 24% of 99 oral cavity samples, 44% of 100 hides, 10% of 68 fecal samples collected postevisceration, 6% of 100 prechill carcass swabs, and 15% of 40 fecal samples collected from holding pens. E. coli O157 was not isolated from rumen or postchill carcass samples. E. coli O157 was isolated from at least one sample from each group of cattle tested, and the prevalence in different groups ranged from less than 1 to 41%. The numbers of E. coli O157 differed among the animals groups. The group which contained the highest fecal (7.5 x 10(5) MPN/g) and hide (22 MPN/cm2) counts in any individual animal was the only group in which E. coli O157 was isolated from carcasses, suggesting a link between the numbers of E. coli O157 present and the risk of carcass contamination. Processing practices at this abattoir were adequate for minimizing contamination of carcasses, even when animals were heavily contaminated with E. coli O157.     

Enumeration of coliforms and Escherichia coli in frozen black tiger shrimp Penaeus monodon by conventional and rapid methods

Conventional (most probable number, MPN) and rapid methods-including Chromocult coliform agar (CCA), Fluorocult(R) LMX broth (LMX), and Petrifilm Escherichia coli count plates (PEC) for enumeration of coliforms and E. coli in frozen black tiger shrimp from Thailand were compared in order to assess the possibility of using one of the rapid methods for routine analysis. Enumeration of coliforms and E. coli from 18 samples of regular frozen black tiger shrimp and 156 samples of frozen black tiger shrimp experimentally contaminated with coliforms or E. coli at concentrations of approximately 10, approximately 10(2), and approximately 10(3) CFU g(-1) revealed that at the level of approximately 10 CFU g(-1), coliform numbers ranked as LMX>CCA>MPN=PEC and E. coli as MPN=LMX=PEC=CCA. At the level of approximately 10(2) CFU g(-1), coliform numbers ranked as LMX>MPN=PEC=CCA and E. coli as MPN=LMX>PEC=CCA. At the level of 10(3) CFU g(-1), coliforms ranked as LMX>MPN=CCA>PEC and E. coli as MPN>LMX>CCA>PEC. Agreements with the conventional MPN method for coliforms were LMX 108%, PEC 87.2%, and CCA 91.2% and agreements for E. coli were LMX 101%, PEC 95.7%, and CCA 96.3%. Sensitivities (%) ranked LMX>MPN>CCA=PEC for coliforms and E. coli, whereas equal specificities (100%) of all methods for coliforms and E. coli were demonstrated. Rankings for the other parameters compared were: convenience, PEC>CCA=LMX>MPN; time to detection, MPN>LMX=PEC=CCA; expense, MPN=PEC>CCA>LMX; labor, MPN>LMX=CCA>PEC; accuracy for coliforms, PEC>CCA>MPN>LMX; and accuracy for E. coli, PEC=CCA>LMX>MPN.     

Coliform, Escherichia coli, and salmonellae concentrations in a multiple-tank, counterflow poultry scalder

Scald water samples from a commercial broiler processing plant were tested for coliforms, Escherichia coli, and salmonellae to evaluate the numbers of suspended bacteria in a multiple-tank, counterflow scalder. Water samples were taken from each of three tanks on 8 different days after 6-week-old broilers had been processed for 8 h. Coliforms and E. coli were counted using Petrifilm, and the most probable number (MPN) of salmonellae was determined both in water samples and in rinses of defeathered carcasses that were removed from the processing line immediately after taking the water samples. Mean coliform concentrations in tanks 1, 2, and 3 (the last tank that carcasses pass through before being defeathered) were 3.4, 2.0, and 1.2 log10(CFU/ml), respectively. E. coli concentrations followed the same pattern with means of 3.2, 1.5, and 0.8 in tanks 1, 2, and 3, respectively, with significant differences (P < 0.02) in the concentrations of both coliforms and E. coli between the tanks. Sixteen of 24 scald-water samples were positive for salmonellae with a geometric mean of 10.9 MPN/100 ml in the positive samples. Salmonellae were isolated from seven of eight water samples from both tanks 1 and 2, but in only two of eight water samples from tank 3, the last tank that carcasses pass through. It appears that most bacteria removed from carcasses during scalding are washed off during the early part of scalding.     

One-year (2003) nationwide pork carcass microbiological baseline data survey in Taiwan

From January through December 2003, swab samples from 1,650 pork carcasses were collected from 39 slaughter plants in Taiwan. These samples were analyzed for the prevalence of indicator microorganisms and specific pathogens. Viable aerobic bacteria, total coliforms, and Escherichia coli were recovered from 100, 95.3, and 87.5% of these carcasses, respectively. Of those carcasses that harbored bacteria, the mean aerobic plate, total coliform, and Escherichia coli counts were 4.0, 0.6, and 0.1 log CFU/cm2, respectively. Staphylococcus aureus, Clostridium perfringens, Campylobacter jejuni, Campylobacter coli, Listeria monocytogenes, and Salmonella were recovered from 4.8, 0.3, 13.8, 0.7, and 1.7 of 1,038 carcasses, respectively. E. coli O157:H7 was not detected from any carcass. When positive for a specific pathogen, the mean carcass concentration was 0.57 log CFU/cm2 for S. aureus, 0.66 most probable number (MPN)/cm2 for C. jejuni and C. coli, and 0.18 MPN/cm2 for Salmonella. The findings of this study will help provide a reference for establishing hygienic standards and a criterion for evaluating the effects of slaughtering operations in Taiwan.     

Isolation of Campylobacter spp. from a pig slaughterhouse and analysis of cross-contamination

The purpose of this study was to establish the prevalence and possible contamination routes of Campylobacter spp. in a pig slaughterhouse. Swab samples were taken from the last part of rectum, from the carcasses surface before meat inspection and from slaughter line surface from 4 different pig herds during slaughtering. Identification of Campylobacter isolates was determined by the use of phase-contrast microscopy, hippurate hydrolysis, indoxyl acetate hydrolysis tests and PCR based restriction fragment length polymorphism method (PCR-RFLP). Pulsed-field gel electrophoresis (PFGE) typing using two macro-restriction enzymes SmaI and SalI was applied to in-slaughterhouse contamination analysis of pig carcasses. The study showed that 28 (63.6%) of the 44 samples collected at slaughterhouse were contaminated by Campylobacter spp. Up to 5 different colonies were obtained from each swab sample and a total of 120 different isolates were collected. 23.4% (28 of 120) isolates were identified as C. jejuni (19 from carcasses and 9 from slaughter line surfaces) and 76.6% (92 of 120) isolates as C. coli (28 from faeces, 47 from carcasses and 17 from slaughter line surfaces). The typing results showed identity between isolates from successive flocks, different carcasses, and places in the slaughterhouse in contact with carcasses. The results suggest that cross-contamination originated in the gastro-intestinal tract of the slaughtered pigs and that cross-contamination happened during the slaughter process.     

Prevalence and Concentration of Arcobacter spp. on Australian Beef Carcasses

The International Commission on Microbiological Specifications for Foods (ICMSF) classified Arcobacter spp. as emerging pathogens in 2002. Arcobacter spp. have been isolated from numerous food products at retail and from animal carcasses and feces at slaughter. A survey was conducted to determine both the prevalence and concentration of Arcobacter spp. on prechill beef carcasses. Surface swab samples were collected from 130 beef carcasses at the end of processing, prior to chilling. The concentration of Arcobacter spp. was determined by a most-probable-number per square centimeter (3 by 3) method with a limit of detection of 0.12 CFU/cm(2). Of the 100 carcasses examined from export abattoirs, 20 (20.0%) were contaminated with Arcobacter spp., and 5 of these had quantifiable levels of contamination ranging from 0.12 to 0.31 CFU/cm(2). Of the 30 carcasses examined at a pet food abattoir, 25 (83.3%) were contaminated with Arcobacter spp., and 10 of these had quantifiable levels of contamination ranging from 0.12 to 0.95 CFU/cm(2). Three species of Arcobacter, A. butzleri, A. cryaerophilus, and A. skirowii, were identified by PCR. Each of the species was present in an approximately equal ratio from export abattoirs. This study demonstrates that slaughter practices at export abattoirs are sufficient to maintain both low prevalence and low levels of contamination of beef carcasses with Arcobacter spp.     

Characterization of O157:H7 and other Escherichia coli isolates recovered from cattle hides, feces, and carcasses

In a previous study, the seasonal prevalence was reported for stx+ Escherichia coli O157:H7 in feces and on hides and carcasses of cattle at processing. Overall, 1,697 O157:H7 isolates have now been characterized for the incidence of (i) eae(O157), hlyA, stx1, and stx2 in the recovered isolates and (ii) presumptive rough and presumptive nonmotile isolates. Seven O157:H7 isolates (0.4%) lacked stx genes, although they carried eae and hlyA. All but one of the isolates carried both eae and hlyA. Approximately two-thirds of the isolates (64% when one isolate per sample was considered) carried both stx1 and stx2. E. coli O157:H7 cells that harbored both stx1 and stx2 were more often recovered from hides in the fall (79% of the fall hide isolates) and winter (84% of the winter hide isolates) than in the spring (53%) and summer (59%). Isolates recovered from preevisceration carcasses showed a similar but not statistically significant trend. Twenty-three of the 25 O157:H7 isolates carrying stx1 but not stx2 were recovered during summer. Fifteen presumptive rough and 117 presumptive nonmotile stx+ O157:H7 isolates were recovered. Ten (67%) of the presumptive rough isolates were recovered during summer. Ninety-five of the presumptive nonmotile isolates (81%) were recovered during fall. Forty-eight percent of the false-positive isolates (175 of 363) tentatively identified as O157:H7 were O157+ H7- and lacked eae(O157), hlyA, and stx. These data suggest that in beef processing samples (i) there are minor seasonal variations in the prevalence of stx genes among E. coli O157:H7 isolates, (ii) presumptive rough and presumptive nonmotile stx+ O157:H7 isolates are present, (iii) E. coli O157:H7 isolates lacking stx genes may be rare, and (iv) O157+ H7- isolates lacking stx genes can result in many false-positive results.     

The enumeration of coliforms and E. Coli on naturally contaminated beef: A comparison of the petrifilm(™) method with the Australian Standard

Petrifilm(?) PEC was compared to Australian Standard (AS) methods for the enumeration of coliforms and Escherichia coli on 50 naturally contaminated beef samples from three meat works. The standard methods consist of a 3-tube most probable number test or a direct plate count on tryptone bile agar for E. coli, and violet red bile agar and the most probable number test for conliorms (AS 1766.2.12.1984 and AS 1766.2.3.1992). No significant difference was found between the methods, except that the count of E. coli on the direct plate method with a resuscitation step was significantly higher than the count on Petrifilm(?), most probable number or direct plate count without resuscitation.     

A study of the prevalence and enumeration of Salmonella enterica in cattle and on carcasses during processing

Salmonella prevalence and counts were estimated for samples from the oral cavity, hide, rumen, and feces of 100 cattle at slaughter and from the pre- and postchill carcasses of these cattle. Samples were collected from 25 consecutively slaughtered cattle from each of four unrelated groups slaughtered at a single abattoir on different days. Ten additional fecal samples from each group were collected from their respective abattoir holding pens prior to slaughter. The prevalence of Salmonella was estimated using automated immunomagnetic separation, and the counts were estimated using a combination of most probable number (MPN) and automated immunomagnetic separation. A total of 606 samples were collected with Salmonella isolated from 157 (26%), including 29% of oral cavities, 68% of hides, 16% of feces collected after evisceration, 25% of rumen samples, 2% of prechill carcasses, 3% of postchill carcasses, and 48% of feces collected from holding pens. The prevalence and count of Salmonella varied between the different groups of animals tested. The highest count obtained was from a rumen sample (1.1 x 10(4) MPN/g). Other counts were generally low, with a maximum count in feces collected after evisceration and in the abattoir holding pens of 93 and 23 MPN/g, respectively. The highest count on hides, in oral cavities, and on carcasses was 4.8 MPN/cm2, 23 MPN/g, and 0.31 MPN/cm2, respectively. Even though Salmonella was present on the hides and in the rumen and feces of at least one animal from each group of cattle, the processing of animals at this abattoir resulted in few contaminated carcasses, and when contamination occurred, Salmonella was detected at low numbers.     

A national survey of the microbiological quality of beef carcasses and frozen boneless beef in Australia

The third national baseline microbiological survey of Australian beef carcasses and frozen boneless beef was conducted in 2004. Carcasses (n=1155) sampled at 27 slaughter establishments had a mean aerobic plate count (at 25 degrees C) of 1.3 log CFU/cm2. Escherichia coli was isolated from 8.0% of the cacasses, with a mean count of -0.8 log CFU/cm2 for positive samples. On samples from 24 boning (fabrication) plants (n=1082), the mean aerobic plate count for frozen boneless beef was 1.3 log CFU/g, and the mean count for the 1.8% of samples with detectable E. coli was 1.5 log CFU/g. E. coli O157: H7 was isolated from 1 of 1,143 carcasses and from 0 of 1082 boneless samples. Salmonella was isolated from 0 of 1155 carcasses and from 1 of 1082 samples of boneless product. No Campylobacter spp. were isolated from carcasses or boneless beef. Coagulase-positive staphylococci were isolated from 28.7% of beef carcasses and 20.3% of boneless beef samples, and positive samples had a mean count of 0.3 log CFU/cm2 and 0.8 log CFU/g, respectively.     

Postchill campylobacter prevalence on broiler carcasses in relation to slaughter group colonization level and chilling system

Data from an ongoing national surveillance program of Campylobacter prevalence in broiler slaughter groups were related to results from a 1-year baseline study of broiler carcasses postchill. The goals were to establish the relation between Campylobacter prevalence in slaughter groups and on carcasses and to determine the effect of various chilling systems on Campylobacter prevalence. Pooled cloacal and neck skin samples from the surveillance program were analyzed after enrichment. Carcass rinse samples from the baseline study were analyzed after enrichment and by direct plating. Data from both studies were available for 614 carcasses. Direct-plating analyses indicated that the percentages of carcasses positive for Campylobacter jejuni and other Campylobacter spp. in slaughter groups with negative cloacal samples were 2 and 10%, respectively, whereas enrichment analyses indicated prevalences of 2% in both cases. Campylobacter prevalence in slaughter groups with a high degree of intestinal colonization (more than half of the pooled cloacal samples positive) was significantly higher than in slaughter groups with a low degree of colonization (76 to 85% and 30 to 50%, respectively, depending on Campylobacter spp. and analytical method). The prevalence of Campylobacter-positive carcasses postchill was at the same level as the prevalence of carcasses that originated from slaughter groups with positive neck skin samples at four of the six slaughterhouses. Only at one slaughterhouse, with an air-chilling system, was the postchill prevalence (13%) lower than that expected from slaughter group data (23%). The postchill prevalence (43%) was higher than that expected from slaughter group data (33%) at one slaughterhouse with immersion chilling.     

Escherichia coli O157 prevalence and enumeration of aerobic bacteria, Enterobacteriaceae, and Escherichia coli O157 at various steps in commercial beef processing plants

The effectiveness of current antimicrobial interventions used in reducing the prevalence or load of Escherichia coli O157 and indicator organisms on cattle hides and carcasses at two commercial beef processing plants was evaluated. Sponge sampling of beef cattle was performed at five locations from the initial entry of the animals to the slaughter floor to the exit of carcasses from the "hotbox" cooler. For each sample, E. coli O157 prevalence was determined and total aerobic bacteria, Enterobacteriaceae, and E. coli O157 were enumerated. E. coli O157 was found on 76% of animal hides coming into the plants, but no carcasses leaving the cooler were identified as contaminated with E. coli O157. A positive relationship was seen between the incidence of E. coli O157 in hide samples and that in preevisceration samples. Aerobic plate counts and Enterobacteriaceae counts averaged 7.8 and 6.2 log CFU/100 cm2, respectively, on hides, and 1.4 and 0.4 log CFU/100 cm2, respectively, on chilled carcasses. Aerobic plate counts and Enterobacteriaceae counts on preevisceration carcasses were significantly related to the respective levels on the corresponding hides; the carcasses of animals whose hides carried higher numbers of bacteria were more likely to carry higher numbers of bacteria. Implementation of the sampling protocol described here would allow processors to evaluate the efficacy of on-line antimicrobial interventions and allow industrywide benchmarking of hygienic practices.     

Salmonella spp. and Escherichia coli biotype I on swine carcasses processed under the hazard analysis and critical control point-based inspection models project

The present study examined the prevalence of Salmonella spp. and the prevalence and quantity of generic (biotype I) Escherichia coli on carcasses or in pig feces at a pork processing plant operating under the hazard analysis and critical control point-based inspection models project (HIMP) program. The surfaces of carcasses were sponged on 10 separate days over a 30-day period at two processing steps: (i) immediately following exsanguination (100 carcasses), and (ii) after the carcasses were washed, eviscerated, and chilled overnight (122 carcasses). Feces were also collected from 60 of the 100 sponged, postexsanguinated pigs. Salmonella spp. were detected on 73.0% of the 100 postexsanguinated pigs, in 33.3% of the 60 fecal samples, and on 0.7% of the 122 chilled carcasses. E. coli was found on 100.0% of the postexsanguinated pigs and on 30.1% of chilled carcasses tested. The mean concentration of E. coli on carcasses was 1,700 CFU/cm2 immediately after the exsanguination step and 1.1 CFU/cm2 at the chilled carcass stage. Previous studies at this processing plant showed that the pre-HIMP baseline level of Salmonella spp. on the chilled carcasses was 0.8%, indicating that the present HIMP inspection system produced an equivalent level of bacteriological performance.     

The effects on the microbiological condition of product of carcass dressing, cooling, and portioning processes at a poultry packing plant

The log mean numbers of aerobes, coliforms, Escherichia coli and presumptive staphylococci plus listerias on chicken carcasses and carcass portions at various stages of processing at a poultry packing plant were estimated from the numbers of those bacteria recovered from groups of 25 randomly selected product units. The fractions of listerias in the presumptive staphylococci plus listerias groups of organisms were also estimated. Samples were obtained from carcasses by excising a strip of skin measuring approximately 5 x 2 cm(2) from a randomly selected site on each selected carcass, or by rinsing each selected carcass portion. The log mean numbers of aerobes, coliforms, E. coli and presumptive staphylococci plus listerias on carcasses after scalding at 58 degrees C and plucking were about 4.4, 2.5, 2.2 and 1.4 log cfu/cm(2), respectively. The numbers of bacteria on eviscerated carcasses were similar. After the series of operations for removing the crop, lungs, kidneys and neck, the numbers of aerobes were about 1 log unit less than on eviscerated carcasses, but the numbers of the other bacteria were not substantially reduced. After cooling in water, the numbers of coliforms and E. coli were about 1 log unit less and the numbers of presumptive staphylococci plus listerias were about 0.5 log unit less than the numbers on dressed carcasses, but the numbers of aerobes were not reduced. The numbers of aerobes were 1 log unit more on boneless breasts, and 0.5 log units more on skin-on thighs and breasts that had been tumbled with brine than on cooled carcasses; and presumptive staphylococci plus listerias were 0.5 log unit more on thighs than on cooled carcasses. Otherwise the numbers of bacteria on the product were not substantially affected by processing. Listerias were <20% of the presumptive staphylococci plus listerias group of organisms recovered from product at each point in the process except after breasts were tumbled with brine, when >40% of the organisms were listerias.     

Prevalence and characterization of typical and atypical Escherichia coli from fish sold at retail in Cochin, India

Escherichia coli is a common contaminant of seafood in the tropics and is often encountered in high numbers. The count of E. coli as well as verotoxigenic E. coli O157:H7 was estimated in 414 finfish samples composed of 23 species of fresh fish from retail markets and frozen fish from cold storage outlets in and around Cochin, India. A total of 484 presumptive E. coli were isolated, and their indole-methyl red-Voges-Proskauer-citrate (IMViC) pattern was determined. These strains were also tested for labile toxin production by a reverse passive latex agglutination method and checked for E. coli serotype O157 by latex agglutination with O157-specific antisera. Certain biochemical marker tests, such as methylumbelliferyl-beta-glucuronide (MUG), sorbitol fermentation, decarboxylase reactions, and hemolysis, which are useful for screening pathogenic E. coli, were also carried out. Results showed that 81.4% of the E. coli isolates were sorbitol positive. Among this group, 82% were MUG positive, and 14.46% of the total E. coli isolates showed human blood hemolysis. None of the isolates were positive for agglutination with E. coli O157 antisera nor did any produce heat-labile enterotoxin. This study indicates that typical E. coli O157 or labile toxin-producing E. coli is absent in the fish and fishery environments of Cochin (India). However, the presence of MUG and sorbitol-negative strains that are also hemolytic indicates the existence of aberrant strains, which require further investigation.