Comparison of three protocols for the isolation of Arcobacter from poultry.

The microaerophilic bacterium Arcobacter has received increasing attention in recent years regarding its presence in food products. There exist a limited number of methods for the detection of this microorganism, with currently available methods being cumbersome to perform, time consuming, and limited in specificity. The objective of this study was to develop a selective enrichment broth to isolate accurately three Arcobacter spp. from concentrated chicken microflora by comparing the efficacy of various selective and growth-promoting additives in order. This newly developed enrichment broth was incorporated into an isolation protocol using a previously developed plating medium, and this new protocol was compared with two existing methods for the isolation of Arcobacter from poultry. Method 1 consisted of enrichment in Ellinghausen-McCullough-Johnson-Harris Polysorbate 80 broth followed by plating on cefoperazone-vancomycin-amphotericin B medium. Method 2 consisted of enrichment in Arcobacter selective broth and plating onto Arcobacter selective medium. Method 3 (the JM method), used a newly developed enrichment broth followed by plating on a previously described JM agar. The JM method isolated Arcobacter strains in 42 out of 50 broiler chicken samples, while methods 1 and 2 detected the organism in only 24 and 15 out of 50 samples, respectively.     

Sensitivity of three methods used in the isolation of Arcobacter spp. in raw ground pork

Arcobacter, an aerotolerant Campylobacter-like organism, has been designated an emerging pathogen because of its newly recognized ability to cause diarrheal illness in both humans and animals and its presence in the human food supply. Because there is no standard isolation method for its detection, the true occurrence of this pathogen is largely unknown. In addition, the lack of a standardized isolation protocol limits the ability of investigators to compare field data. Arcobacter has been detected in whole muscle and ground pork at various levels by two different isolation methods (those of deBoer and Collins). In this study, these methods were tested along with the Johnson-Murano (JM) method, developed in our laboratory. The sensitivity of each method was tested for ground pork inoculated with Arcobacter butzleri and Arcobacter cryaerophilus IA at levels of 10(4), 10(3), 10(2), and 10(1) CFU/g. Controls included tubes with uninoculated pork and broth tubes without pork. All samples that were morphologically similar to Arcobacter were analyzed by Gram staining and by catalase and oxidasereactions. Presumptive positive samples were confirmed by the polymerase chain reaction. The JM method was determined to be the most sensitive, detecting A. butzleri down to a level of 10(1) CFU/g in 100% of the samples and detecting A. cryaerophilus IA at a level of 10(1) CFU/g in 75% of samples. In a pure buffer system, the Collins method was as effective as the JM method in isolating both organisms to levels of 10(1) cells per g.     

A comparison of three methods for the isolation of Arcobacter spp. from retail raw poultry in Northern Ireland

Recent evidence suggests that arcobacters, especially Arcobacter butzleri, are potential foodborne pathogens, but standardized detection methods have yet to be established. A study was undertaken to determine which of three isolation methods was the most effective for the isolation of Arcobacter spp. from fresh raw poultry. Methods 1 was microaerobic and involved a membrane filtration step followed by plating onto blood agar. Method 2 was also microaerobic and involved enrichment and plating media containing a five-antibiotic cocktail. Method 3 was aerobic and was based on enrichment in a charcoal-based broth containing two antibiotics. Retail poultry samples (n = 50) were obtained from supermarkets in Northern Ireland; the European Community license number was recorded to ensure sample diversity. Presumptive arcobacters were identified using genus-specific and species-specific primers. Methods 1 resulted in the lowest recovery of arcobacters (28% of samples positive). The detection rate for method 2 (68%) was higher than that for method 3 (50%), but the difference was not significant (P > 0.05). Modification of method 3 by plating the enrichment broth at 24 h, as well as at 48 h, increased recovery to 68%. Use of methods 2 and 3 together increased the number of positive samples detected by approximately 25% compared with use of either method alone. A. butzleri was the most commonly isolated species using all methods. Method 3 detected Arcobacter cryaerophilus in more samples (n = 3) than did method 1 and 2 (n = 1). Arcobacter skirrowii was detected by only method 3 (n = 1). In terms of sensitivity, ease of use, and diversity of species recovered, modified method 3 was the overall method of choice.     

A survey of the incidence of E. coli O157 in the UK dairy industry

A survey of the incidence of Escherichia coli O157 in bovine faeces, pasteurised and unpasteurised dairy products, farm swabs and dairy factory environmental samples was undertaken. A single enrichment broth was employed, together with three detection methods, comprising a plating medium, a commercially available ELISA technique (Petrifilm) and an ELISA test under development (Organon-Teknika). For all detection methods, the efficiency of recovery, determined using artificially contaminated samples, was poor and this was attributed to the growth of competitors in the enrichment broth. Both the plating and the Organon-Teknika methods yielded a higher proportion of false positives than the Petrifilm method; however, the former two methods also detected a wider range of verotoxigenic E. coli than the Petrifilm method. Verotoxigenic E. coli were not detected in any of 1146 samples examined. The poor performance of the methodolgy may explain why the environmental incidence appears to be low although the incidence of infection by E. coli O157 is increasing.     

Clostridium difficile from healthy food animals: optimized isolation and prevalence

Two isolation methods were compared for isolation of Clostridium difficile from food animal feces. The single alcohol shock method (SS) used selective enrichment in cycloserine-cefoxitin fructose broth supplemented with 0.1% sodium taurocholate, followed by alcohol shock and isolation on tryptic soy agar supplemented with 5% sheep blood, and cycloserine-cefoxitin fructose agar. The double alcohol shock method (DS) used alcohol shock prior to and after selective enrichment in cycloserine-cefoxitin fructose broth supplemented with 0.1% sodium taurocholate, followed by isolation on tryptic soy agar supplemented with 5% sheep blood and cycloserine-cefoxitin fructose agar. A total of 55 (15.9%, n = 345) swine fecal samples, 32 (2.4%, n = 1,325) dairy cattle fecal samples, and 188 (6.3%, n = 2,965) beef cattle fecal samples were positive for C. difficile by either method. However, the DS was significantly better than the SS for the recovery of C. difficile from swine feces, while the SS was significantly better than the DS for the recovery of C. difficile from beef cattle feces. There was no significant difference between methods for the recovery of C. difficile from dairy cattle feces. This study suggests that food animals might harbor C. difficile and it provides critical information that isolation methods might not have universal application across animal species.     

Evaluation of enrichment procedures for recovering Listeria monocytogenes from dairy products

Six different enrichment media and five selective plating media were compared for their suitability for the recovery of Listeria monocytogenes from dairy products. These included media used to test milk products by the U.S. Food and Drug Administration (FDA) and the U.S. Centers for Disease Control (CDC), and media developed by the U.S. Department of Agriculture (USDA) for testing meat and poultry products. Test samples included naturally contaminated goat's milk, cultured milk products and ice cream manufactured with L. monocytogenes, and unpasteurized milk inoculated with heat- and freeze-injured cells of L. monocytogenes. Generally, the media and two-stage enrichment protocol developed by the USDA, with plating of samples after two consecutive 24-h incubation periods, yielded better recoveries than all other enrichment media incubated for 24 h. A modified USDA procedure, incorporating nonselective pre-enrichment of samples by omitting acriflavine and nalidixic acid from the primary USDA enrichment broth, and transfer of a larger volume of the initial culture broth to the secondary enrichment media, significantly increased recoveries of low numbers of sublethally stressed L. monocytogenes. Prolonged incubation of samples in the FDA enrichment broth, for 7 days, did not consistently improve recoveries over the initial 24-h incubation time of the medium. The selective plating medium developed by the USDA, lithium chloride-phenylethanol-moxalactam agar, was the most effective plating agar for isolation of L. monocytogenes following enrichment of samples in any broth culture, and increased recoveries of L. monocytogenes by 19-40% compared with other selective agar media tested.     

Occurrence of verocytotoxin-producing Escherichia coli in dairy and meat processing environments

From June 1999 to June 2000, 480 environmental swabs were collected from two abattoirs in Northern Ireland. In addition, from July 1999 to July 2000, 420 samples originating from raw cow's milk were collected from two Northern Ireland dairies. All samples were examined for the presence of verocytotoxin-producing Escherichia coli (VTEC). O157 with the use of selective enrichment in tryptone soya broth (TSB) and double-strength MacConkey broth purple (MBP) followed by immunomagnetic separation and selective plating onto sorbitol MacConkey agar supplemented with cefixime tellurite. Non-O157 VTEC was detected by selective enrichment in TSB-MBP and plating on MacConkey agar. A multiplex polymerase chain reaction assay was also used to detect the presence of the VT1, VT2, and eae genes. Two (0.42%) of the 480 abattoir samples tested positive for VTEC; one isolate carried the VT2 gene only, and the other carried both the VT2 and the eae genes. Nine (2.14%) of the 420 dairy samples tested positive for VTEC; four carried the VT2 gene only, four carried both the VT2 and the eae genes, and one carried both the VT1 and the eae genes. These results indicate that the incidence of VTEC was low in the dairy and meat processing environment samples tested, and this finding may help to explain the low incidence of VTEC reported for the local human population.     

Detection of Salmonella spp. in tropical seafood by polymerase chain reaction

The incidence of Salmonella spp. in tropical seafood was studied using standard microbiological techniques and polymerase chain reaction (PCR). Six of 20 finfish (30%), 4 of 20 clams (20%) and 1 of 20 shrimp (5%) were positive by culture techniques and by PCR. In a comparative study of different selective enrichment broths and selective plating media, more than one enrichment broth and selective agar were found to be necessary for efficient detection of Salmonella from seafood. Selenite cystine broth (SCB) was found to be more efficient compared to tetrathionate broth (TTB) while both bismuth sulfite agar (BSA) and hektoen enteric agar (HEA) were equally effective as selective plating media for fish. In the case of clams, HEA was found to be more effective. The presence of Salmonella spp. could be detected by PCR amplification of DNA extracted directly from the enrichment broths. In two cases, enrichment broths that were positive by PCR did not yield Salmonella by conventional methods.     

Comparison of methods for recovery and enumeration of Campylobacter from freshly processed broilers.

Most traditional Campylobacter detection and enumeration procedures are difficult and time consuming. Estimations of Campylobacter populations by the most probable number (MPN) method are especially laborious. The objective of this collaborative study, performed in duplicate in Agricultural Research Service and Food Safety Inspection Service laboratories, was to compare two MPN procedures (utilizing different selective enrichment broths and plating media) to the direct plating technique for enumeration of Campylobacter from freshly processed (postchill, postdrip) broiler chicken carcasses. Results obtained from the direct plating of carcass rinse samples on Campy-cefex agar were not significantly different (P > 0.05) from an MPN procedure employing Hunt's Campylobacter selective enrichment broth followed by recovery on modified Campylobacter charcoal differential agar. However, both of these procedures provided significantly (P < 0.05) better recovery than a second MPN procedure using Rosef's selective enrichment broth followed by plating on Mueller-Hinton blood agar with antibiotics. The direct plating method offers a more simple, less expensive, more rapid alternative to traditional MPN procedures for estimating Campylobacter populations associated with freshly processed broiler carcasses.     

Comparison of weep and carcass rinses for recovery of Campylobacter from retail broiler carcasses

Campylobacter is frequently recovered from broiler carcasses. Carcass rinsing is a commonly used procedure for isolating Campylobacter from poultry. A viscous fluid, or weep, exudes from broiler carcasses that have been packaged. This fluid can contain bacteria that were attached to the carcass and represents a potential means of detecting Campylobacter-contaminated carcasses through cultural analysis. Experiments were conducted to compare the efficacy of a weep sampling method with that of a carcass rinse method. For both trials, retail carcasses were purchased. Packages were opened, and 0.1-ml aliquots of weep fluid from the retail packages were plated onto Campy-cefex agar. Carcasses were removed from the package and rinsed in 100 ml of sterile water. Next, 0.1-ml aliquots of the rinsate were plated onto Campy-cefex agar and incubated. In a second experiment, samples were both directly plated and enriched in Bolton enrichment broth. In the first experiment, 35 of 60 carcass rinses tested positive for Campylobacter, while 29 of 60 weep samples yielded Campylobacter isolates with levels of 1.0 and 1.1 log CFU/ml, respectively. In the second experiment, Campylobacter was recovered from 9 of 40 rinse samples and from 13 of 40 weep samples by direct plating, while the organism was recovered from 28 of 40 rinses samples and from 23 of 40 carcass samples by enrichment. There was no significant difference between the two methods with respect to Campylobacter prevalence as determined by the chi-square test. Campylobacter levels recovered by both methods averaged 0.9 log CFU/ml. The sampling of weep fluid was a simple, effective means of detecting this important human enteropathogen on broiler carcasses.     

Isolation of Yersinia enterocolitica from foods.

Many selective enrichment and plating media for the isolation of Yersinia enterocolitica from foods are described. However, at present no single isolation procedure is available for the recovery of all pathogenic strains of Yersinia enterocolitica. Cold enrichment in phosphate-buffered saline plus 1% sorbitol and 0.15% bile salts (PBSSB) and two-step enrichment with tryptone soy broth (TSB) and bile oxalate sorbose (BOS) broth are very efficient methods for the recovery of a wide spectrum of serotypes of Y. enterocolitica. Enrichment in irgasan ticarcillin chlorate (ITC) broth was found to be the most efficient method for the recovery of strains of serotype 0:3, which is the most common clinical serotype of Y. enterocolitica in Europe. Post-enrichment alkali treatment often results in higher isolation rates. Cefsulodin irgasan novobiocin (CIN) agar and Salmonella-Shigella deoxycholate calcium chloride (SSDC) agar are the most commonly used plating media. For the recovery of serotype 0:8 strains, the common clinical isolates in North America, enrichment in BOS and plating on CIN seems the most efficient procedure. Selection of the proper enrichment procedure will depend on the bio/serotypes of Yersinia spp. sought and on the type of food to be examined. The use of more than one medium for both enrichment and plating will result in higher recovery rates of Yersinia spp. from foods. Parallel use of the following two isolation procedures is recommended. (1) Enrichment in ITC for 2 days at 24 degrees C; plating on SSDC agar (2 days at 30 degrees C). (2) Pre-enrichment in TSB for 1 day at 24 degrees C; enrichment in BOS for 5 days at 24 degrees C; alkali treatment (mixing 0.5 ml enriched broth with 4.5 ml of 0.5% KOH in 0.5% NaCl for 5 s); plating on CIN agar (2 days at 24 degrees C).     

Evaluation of immunomagnetic separation and plating media for recovery of Salmonella from meat

Immunomagnetic separation (IMS) was compared with selective enrichment in selenite cystine (SC) broth for isolation of Salmonella from 86 artificially contaminated ground beef samples. Both Rambach agar (RA) and Hektoen enteric (HE) agar were used as selective plating media. The highest count of Salmonella colonies per plate was obtained after enrichment in SC broth and plating on RA (mean value: 111.1+/-58.1 CFU per plate); the lowest count was obtained after IMS and plating on HE agar (mean value: 65.4+/-36.6 CFU per plate). Salmonella in preenrichment was concentrated 1.7-fold by IMS and represented 31% of the microbial population captured by the beads, but nonspecific binding was high. As a result of the large numbers of competing bacteria, isolations on both RA and HE agar following IMS were quite difficult (mean value for Salmonella colonies: 79.9+/-42.7 CFU per plate; mean value for non-Salmonella colonies: 144.1+/-75.7 CFU per plate; ratio of Salmonella to non-Salmonella colonies: 0.8). This study indicates that SC broth is superior to IMS in the isolation of Salmonella from raw ground meat.     

食品中单核细胞增生李斯特菌株的分离及聚合酶链式反应鉴定

目的 建立单核细胞增生李斯特菌的聚合酶链式反应(PCR)检测方法,了解市售食品中单核细胞增生李斯特菌的污染情况.方法 采集成都市市售生畜肉、生禽肉、熟肉制品、水产品、生食蔬菜以及其他熟食等食品样品共135份,采用李氏增菌肉汤(LB1,LB2)进行初增菌,应用选择性分离培养基PALCAM和在TSA-YE平板上进行分离,利用单增李斯特显色平板进行鉴定;根据李斯特菌的特异性基因iap基因设计引物,采用PCR方法检测所有分离的李斯特菌株;根据单增李斯特菌的特异性基因hly基因和prfA基因设计引物检测单核细胞增生李斯特菌株.结果 135份样品中共检出李斯特菌17株,检出率为12.6％;其中单核细胞增生李斯特菌4株,检出率为3.0％.结论 本研究建立的PCR方法具有特异性,本市市售食品不同程度受到李斯特菌的污染.     

Detection of Salmonella enteritidis in shell and liquid eggs using enrichment and plating

Detection methods using various enrichment and plating media and immunoconcentration for Salmonella enteritidis in shell and liquid eggs were evaluated. For liquid egg samples naturally contaminated with S. enteritidis, pre-enrichment in 225 ml of buffered peptone water with cysteine followed by selective enrichment in 10 ml of tetrathionate broth was the superior, resulting in the detection of S. enteritidis in all samples on six of the seven types of selective agar substrate investigated. This enrichment procedure also enabled detection of S. enteritidis in most of artificially inoculated shell egg and pasteurized liquid egg samples.     

Development of a new protocol for the isolation and quantification of Arcobacter species from poultry products.

None of the presently available selective supplements for the specific isolation of Arcobacter species allows the growth of Arcobacter butzleri, A. cryaerophilus and A. skirrowii and at the same time fully suppresses the accompanying flora present in poultry and poultry products. Furthermore, little is known about the contamination levels of poultry with Arcobacter species. In this study, a new selective supplement comprising amphotericin B (10 mg/l), cefoperazone (16 mg/l), 5-fluorouracil (100 mg/l), novobiocin (32 mg/l) and trimethoprim (64 mg/l) was developed. With a new isolation procedure, including enrichment in Arcobacter broth with the selective supplement, incubated for 24 to 48 h at 28 degrees C under microaerobic conditions, arcobacters were isolated from 100% (n = 34) of neck skin of laying hens and from 90% (n = 71) of similar samples from broilers. Of the broiler breast meat samples examined (n = 52), 65% were found to be contaminated with these bacteria. In 64% of the samples, A. butzleri was the only Arcobacter species isolated. In 9% of the samples, A. cryaerophilus was the only species present, while 11% of the samples were positive for both species simultaneously. Using direct isolation on the selective agar medium developed in this study, incubated for 24 to 48 h under microaerobic conditions at 28 degrees C. 32 out of 45 broiler carcasses and 6 out of 25 broiler breast meat samples carried a bacterial load of arcobacters of 10(2) to 10(3) cfu/g. The prevalence of Arcobacter in Belgian poultry was found higher than the prevalence of thermophilic Campylobacter species in each of the poultry categories examined. The enrichment procedure and the direct plating method were validated for the isolation of A. skirrowii. For this species, growth performance was less than the other two Arcobacter species and it was not isolated nor detected by m-PCR from the naturally contaminated poultry samples examined. This new protocol provides a fast and reliable method for the isolation of Arcobacter species from poultry and can contribute to more comprehensive epidemiological investigations.     

Prevalence of Arcobacter spp. in raw ground pork from several geographical regions according to various isolation methods

Studies show that the pathogen Arcobacter is present in beef, poultry, and pork. Several methods have been reported for the isolation of this organism, but none has been adopted as the standard. This has limited the significance of field comparison studies. In the present study, we compared the efficiencies of four Arcobacter isolation methods using raw ground pork collected from slaughter facilities across the United States. We also evaluated the effect of meat fat level and age of animals on the prevalence of Arcobacter in ground pork. The methods chosen for comparison of isolation efficiency were those of Collins, a modified version of the Collins method (Direct Collins), deBoer, and Johnson Murano (JM). These were chosen based on published reports in which they were used to detect Arcobacter in pork products. The JM method was found to be the most successful in consistently detecting Arcobacter, isolating it in 64 of 200 pork samples compared with the Direct Collins method, which isolated Arcobacter in 52 of 200 of those same samples. The Collins method and the deBoer method found Arcobacter present in only a fraction of the samples. The level of contamination was found to vary among the plants, ranging from 0% to 68% prevalence, with 32% overall for all four plants tested. Additionally, ground pork low in fat had a higher contamination frequency (20%) when compared with high-fat pork (4%). Results also showed that meat from younger animals was more frequently contaminated than that from older animals.     

Procedures for the isolation of Campylobacter jejuni and Campylobacter coli from poultry

The effect of different techniques for the isolation of Campylobacter from 198 samples of chicken giblets was studied. Four enrichment broths and two plating media were compared. A protocol of enrichment in Preston or Doyle and Roman's broth followed by plating on Preston agar is recommended for routine use. The duration of incubation of enrichment media was shown to have a significant effect on the number of Campylobacter isolates obtained, 48 h being statistically superior to either 24h or 72h for media incubated at 42°C. Of the 198 samples examined, 177 were found to contain Campylobacter by at least one of the procedures used.     

Development of methods for the recovery of Escherichia coil O157:H7 and Salmonella from beef carcass sponge samples and bovine fecal and hide samples

Culture methods were developed for the concurrent recovery of Escherichia coli O157:H7 and Salmonella from bovine carcass, hide, and fecal samples. Several enrichment conditions were tested for the overall growth of pure cultures; tryptic soy broth for 2 h at 25 degrees C and then for 6 h at 42 degrees C was the protocol selected for use. Immunomagnetic separation (IMS) was incorporated for sensitivity and selectivity, along with a post-IMS enrichment for the recovery of Salmonella as recommended by the manufacturer. Selective agars for plating after IMS were chosen on the basis of ease of target colony identification. Sorbitol MacConkey agar supplemented with cefixime and potassium tellurite and Rainbow agar supplemented with novobiocin and potassium tellurite were chosen for the recovery of E. coli O157:H7. Brilliant green agar with sulfadiazine and Hektoen enteric agar supplemented with novobiocin were selected for the recovery of Salmonella. The resulting methods were evaluated along with standard or previously used methods for the recovery of E. coli O157:H7 and Salmonella from bovine hide and fecal samples and carcass sponge samples. The Meats Research Unit (MRU) methods performed at least as well as the established methods, except that a secondary enrichment in tetrathionate (TT) broth prior to IMS was required for the optimal recovery of Salmonella from feces. Thus, the MRU and MRU-TT methods are effective in the recovery of both E. coli O157:H7 and Salmonella from a single bovine carcass, hide, or fecal sample.     

Comparison of automated BAX PCR and standard culture methods for detection of Listeria monocytogenes in blue Crabmeat (Callinectus sapidus) and blue crab processing plants

This study compared the automated BAX PCR with the standard culture method (SCM) to detect Listeria monocytogenes in blue crab processing plants. Raw crabs, crabmeat, and environmental sponge samples were collected monthly from seven processing plants during the plant operating season, May through November 2006. For detection of L. monocytogenes in raw crabs and crabmeat, enrichment was performed in Listeria enrichment broth, whereas for environmental samples, demi-Fraser broth was used, and then plating on both Oxford agar and L. monocytogenes plating medium was done. Enriched samples were also analyzed by BAX PCR. A total of 960 samples were examined; 59 were positive by BAX PCR and 43 by SCM. Overall, there was no significant difference (P ≤ 0.05) between the methods for detecting the presence of L. monocytogenes in samples collected from crab processing plants. Twenty-two and 18 raw crab samples were positive for L. monocytogenes by SCM and BAX PCR, respectively. Twenty and 32 environmental samples were positive for L. monocytogenes by SCM and BAX PCR, respectively, whereas only one and nine finished products were positive. The sensitivities of BAX PCR for detecting L. monocytogenes in raw crabs, crabmeat, and environmental samples were 59.1, 100, and 60%, respectively. The results of this study indicate that BAX PCR is as sensitive as SCM for detecting L. monocytogenes in crabmeat, but more sensitive than SCM for detecting this bacterium in raw crabs and environmental samples.     

Comparative evaluation of culture- and BAX polymerase chain reaction-based detection methods for Listeria spp. and Listeria monocytogenes in environmental and raw fish samples

Two commercial polymerase chain reaction (PCR)-based Listeria detection systems, the BAX for Screening/Listeria monocytogenes and the BAX for Screening/Genus Listeria, and a culture-based detection system, the Biosynth L. monocytogenes Detection System (LMDS), were evaluated for their ability to detect L. monocytogenes and Listeria spp. in raw ingredients and the processing environment. For detection of L. monocytogenes from raw fish, enrichment was performed in Listeria enrichment broth (LEB), followed by plating on both Oxford agar and LMDS L. monocytogenes plating medium (LMPM). Detection of Listeria and L. monocytogenes from environmental samples was performed using LMDS enrichment medium, followed by plating on both Oxford agar and LMPM. A total of 512 environmental samples and 315 raw fish were taken from two smoked fish processing facilities and screened using these molecular and cultural Listeria detection methods. The BAX for Screening/L monocytogenes was used to screen raw fish and was 84.8% sensitive and 100% specific. The BAX for Screening/Genus Listeria was evaluated on environmental samples and had 94.7% sensitivity and 97.4% specificity. In conjunction with enrichment in LEB, LMPM had a sensitivity and specificity for detection of L. monocytogenes from raw fish of 97.8 and 100%, respectively. Use of LMDS enrichment medium followed by plating on LMPM allowed for sensitivity and specificity rates of 94.8 and 100%, respectively, for detection of L. monocytogenes from environmental samples. We conclude that both the BAX systems and the use of LMPM allow for reliable and rapid detection of Listeria spp. and L. monocytogenes. While the BAX systems provide screening results in about 3 days, the use of LMPM allows for L. monocytogenes isolation in 4 to 5 days.