Presence of Salmonella and Campylobacter spp. in Wild Small Mammals on Organic Farms

The presence of Salmonella and Campylobacter spp. in rodents and insectivores (n = 282) was investigated on organic farms. Infections were encountered in house mice (8 of 83 Campylobacter positive and 1 of 83 Salmonella sp. strain Livingstone positive) and brown rats (1 of 8 Campylobacter positive) but not in other species. No shared Campylobacter genotypes were found between rodent and pig manure isolates. Effective on-farm rodent management is recommended.     

Rapid detection of Campylobacter coli,C. jejuni,and Salmonella enterica on poultry carcasses by using PCR-enzyme-linked immunosorbent assay

Contamination of retail poultry by Campylobacter spp. and Salmonella enterica is a significant source of human diarrheal disease. Isolation and identification of these microorganisms require a series of biochemical and serological tests. In this study, Campylobacter ceuE and Salmonella invA genes were used to design probes in PCR-enzyme-linked immunosorbent assay (ELISA), as an alternative to conventional bacteriological methodology, for the rapid detection of Campylobacter jejuni, Campylobacter coli, and S. enterica from poultry samples. With PCR-ELISA (40 cycles), the detection limits for Salmonella and Campylobacter were 2 x 10(2) and 4 x 10(1) CFU/ml, respectively. ELISA increased the sensitivity of the conventional PCR method by 100- to 1,000-fold. DNA was extracted from carcass rinses and tetrathionate enrichments and used in PCR-ELISA for the detection of Campylobacter and S. enterica, respectively. With PCR-ELISA, Salmonella was detected in 20 of 120 (17%) chicken carcass rinses examined, without the inclusion of an enrichment step. Significant correlation was observed between PCR-ELISA and cultural methods (kappa = 0.83; chi-square test, P < 0.001) with only one false negative (1.67%) and four false positives (6.67%) when PCR-ELISA was used to screen 60 tetrathionate enrichment cultures for SALMONELLA: With PCR-ELISA, we observed a positive correlation between the ELISA absorbance (optical density at 405 nm) and the campylobacter cell number in carcass rinse, as determined by standard culture methods. Overall, PCR-ELISA is a rapid and cost-effective approach for the detection and enumeration of Salmonella and Campylobacter bacteria on poultry.     

Prevalence of Campylobacter spp., Escherichia coli, and Salmonella serovars in retail chicken, turkey, pork, and beef from the Greater Washington, D.C., area.

A total of 825 samples of retail raw meats (chicken, turkey, pork, and beef) were examined for the presence of Escherichia coli and Salmonella serovars, and 719 of these samples were also tested for Campylobacter spp. The samples were randomly obtained from 59 stores of four supermarket chains during 107 sampling visits in the Greater Washington, D.C., area from June 1999 to July 2000. The majority (70.7%) of chicken samples (n = 184) were contaminated with Campylobacter, and a large percentage of the stores visited (91%) had Campylobacter-contaminated chickens. Approximately 14% of the 172 turkey samples yielded Campylobacter, whereas fewer pork (1.7%) and beef (0.5%) samples were positive for this pathogen. A total of 722 Campylobacter isolates were obtained from 159 meat samples; 53.6% of these isolates were Campylobacter jejuni, 41.3% were Campylobacter coli, and 5.1% were other species. Of the 212 chicken samples, 82 (38.7%) yielded E. coli, while 19.0% of the beef samples, 16.3% of the pork samples, and 11.9% of the turkey samples were positive for E. coli. However, only 25 (3.0%) of the retail meat samples tested were positive for Salmonella. Significant differences in the bacterial contamination rates were observed for the four supermarket chains. This study revealed that retail raw meats are often contaminated with food-borne pathogens; however, there are marked differences in the prevalence of such pathogens in different meats. Raw retail meats are potential vehicles for transmitting food-borne diseases, and our findings stress the need for increased implementation of hazard analysis of critical control point (HACCP) and consumer food safety education efforts.     

A survey of Campylobacter species shed in faeces of beef cattle using polymerase chain reaction

A polymerase chain reaction (PCR)-based survey of campylobacters associated with faeces collected from 382 beef cattle was undertaken. To ensure the removal of PCR inhibitors present in faeces and determine if adequate extraction was achieved, faeces were seeded with internal control DNA (i.e., DNA designed to amplify with the Campylobacter genus primer set, but provide a smaller amplicon) before the extraction procedure. In only two samples (0.5%) were the internal control or Campylobacter genus amplicons not detected. In the remaining 380 faecal samples, Campylobacter DNA was detected in 83% of the faecal samples (80% of the faecal samples were positive for Campylobacter genus DNA, and 3% of the samples were negative for Campylobacter genus DNA but positive for DNA of individual species). The most frequently detected species was Campylobacter lanienae (49%), a species only recently connected to livestock hosts. Campylobacter jejuni DNA was detected in 38% of the faecal samples, and Campylobacter hyointestinalis and Campylobacter coli DNA were detected in 8% and 0.5% of the samples, respectively. Campylobacter fetus DNA was not detected. Twenty-four percent of the faecal samples contained DNA of at least two species of Campylobacter. Of these samples, the majority (81%) contained DNA of C. jejuni and C. lanienae. The results of this study indicate that beef cattle commonly release a variety of Campylobacter species into the environment and may contribute to the high prevalence of campylobacteriosis in humans inhabiting areas of intensive cattle production, such as southern Alberta. Furthermore, this study demonstrates the utility of using PCR as a rapid and accurate method for simultaneously detecting the DNA of a diverse number of Campylobacter species associated with bovine faeces.     

Campylobacteriosis, salmonellosis, and shigellosis in free-ranging human-habituated mountain gorillas of Uganda

For conservation purposes and due to growing ecotourism, free-ranging mountain gorillas (Gorilla gorilla beringei) have been habituated to humans. Fecal specimens (n = 62) collected in January 1999 from mountain gorillas of the Bwindi and Mgahinga National Parks, Uganda, were tested for Campylobacter spp., Salmonella spp., and Shigella spp., and the overall prevalence of infection was 19%, 13%, and 6%, respectively. The prevalence of positive specimens was not related to the year of habituation of a gorilla group to humans. Campylobacter spp., Salmonella, and Shigella spp. infections were not distributed equally among the age classes of gorillas; most of the enteropathogens (80%), and all Shigella spp. organisms, S. sonnei, S. boydii, and S. flexneri, were isolated from subadults and adult gorillas with ages ranging from 6.0 to 11.9 yr. The prevalence of Campylobacter spp. and Salmonella spp. infections among human-habituated gorillas has doubled during the last 4 yr, and isolation of Shigella spp. for the first time from mountain gorillas, may indicate enhanced anthropozoonotic transmission of these enteropathogens.     

Detection of Salmonella enterica serovar typhimurium by using a rapid, array-based immunosensor

The multianalyte array biosensor (MAAB) is a rapid analysis instrument capable of detecting multiple analytes simultaneously. Rapid (15-min), single-analyte sandwich immunoassays were developed for the detection of Salmonella enterica serovar Typhimurium, with a detection limit of 8 x 10(4) CFU/ml; the limit of detection was improved 10-fold by lengthening the assay protocol to 1 h. S. enterica serovar Typhimurium was also detected in the following spiked foodstuffs, with minimal sample preparation: sausage, cantaloupe, whole liquid egg, alfalfa sprouts, and chicken carcass rinse. Cross-reactivity tests were performed with Escherichia coli and Campylobacter jejuni. To determine whether the MAAB has potential as a screening tool for the diagnosis of asymptomatic Salmonella infection of poultry, chicken excretal samples from a private, noncommercial farm and from university poultry facilities were tested. While the private farm excreta gave rise to signals significantly above the buffer blanks, none of the university samples tested positive for S. enterica serovar Typhimurium without spiking; dose-response curves of spiked excretal samples from university-raised poultry gave limits of detection of 8 x 10(3) CFU/g.     

Enteropathogenic bacteria in frozen chicken.

Eighty-two samples of frozen chicken from retail stores were examined for the presence of Campylobacter, Yersinia enterocolitica, and salmonellae. Aerobic plate counts and numbers of coliform bacteria at 37 degrees C were determined. Campylobacter fetus subsp. jejuni was found in 22% of the samples, Y. enterocolitica was found in 24.5% and Salmonella typhimurium was found in one sample (1.2%). The isolated strains of Y. enterocolitica belonged to serotypes 4, 5b, 6, and 8. Aerobic plate counts and numbers of coliform bacteria at 37 degrees C were not found to be noticeably higher in samples containing pathogens than in pathogen-free samples. This investigation showed that chicken does contain other pathogenic bacteria than salmonellae. Campylobacter and Y. enterocolitica were isolated in much higher frequencies than Salmonella.     

Incidence of Campylobacter and Salmonella isolated from retail chicken and associated packaging in South Wales

AIMS: To investigate the incidence of Campylobacter and Salmonella contamination associated with supermarket and butchers' shop chicken and related packaging. METHOD AND RESULTS: Three hundred raw samples (whole chicken, chicken breast with skin or chicken pieces) were purchased on a monthly basis for seven months. Packaging associated with the chicken was also sampled to provide isolation data for external and whole packaging. Campylobacter and Salmonella were isolated from 68% and 29% of retail chicken, respectively. Campylobacter was isolated from 3% of external and 34% of whole packaging overall. Salmonella was absent from external packaging but was isolated from 11% of whole packaging. No significant trends in isolation rates of the organisms were obtained during the period of sampling. CONCLUSIONS: The food industry and consumers should be made aware of the potential risk of Campylobacter and Salmonella on both the external and internal surfaces of packaging in addition to chicken itself. SIGNIFICANCE AND IMPACT OF THE STUDY: Chicken and chicken packaging is a potential vehicle for the introduction of pathogens in retail and domestic kitchens and in particular for the cross-contamination of Campylobacter and Salmonella.     

Fecal indicators and zoonotic pathogens in household drinking water taps fed from rainwater tanks in Southeast Queensland, Australia

In this study, the microbiological quality of household tap water samples fed from rainwater tanks was assessed by monitoring the numbers of Escherichia coli bacteria and enterococci from 24 households in Southeast Queensland (SEQ), Australia. Quantitative PCR (qPCR) was also used for the quantitative detection of zoonotic pathogens in water samples from rainwater tanks and connected household taps. The numbers of zoonotic pathogens were also estimated in fecal samples from possums and various species of birds by using qPCR, as possums and birds are considered to be the potential sources of fecal contamination in roof-harvested rainwater (RHRW). Among the 24 households, 63% of rainwater tank and 58% of connected household tap water (CHTW) samples contained E. coli and exceeded Australian drinking water guidelines of <1 CFU E. coli per 100 ml water. Similarly, 92% of rainwater tanks and 83% of CHTW samples also contained enterococci. In all, 21%, 4%, and 13% of rainwater tank samples contained Campylobacter spp., Salmonella spp., and Giardia lamblia, respectively. Similarly, 21% of rainwater tank and 13% of CHTW samples contained Campylobacter spp. and G. lamblia, respectively. The number of E. coli (P = 0.78), Enterococcus (P = 0.64), Campylobacter (P = 0.44), and G. lamblia (P = 0.50) cells in rainwater tanks did not differ significantly from the numbers observed in the CHTW samples. Among the 40 possum fecal samples tested, Campylobacter spp., Cryptosporidium parvum, and G. lamblia were detected in 60%, 13%, and 30% of samples, respectively. Among the 38 bird fecal samples tested, Campylobacter spp., Salmonella spp., C. parvum, and G. lamblia were detected in 24%, 11%, 5%, and 13% of the samples, respectively. Household tap water samples fed from rainwater tanks tested in the study appeared to be highly variable. Regular cleaning of roofs and gutters, along with pruning of overhanging tree branches, might also prove effective in reducing animal fecal contamination of rainwater tanks.     

The prevalence and number of Salmonella in sausages and their destruction by frying,grilling or barbecuing

AIMS: To determine the prevalence and number of Salmonella and Campylobacter in sausages and to evaluate their destruction during cooking. METHODS AND RESULTS: One hundred and sixty-two packs of uncooked economy or catering sausages, comprising 53 packs of frozen and 109 of chilled sausages, were purchased in Devon between March and July 2000. All were tested for the presence of Salmonella and 51 packs of chilled sausages were also examined for the presence of Campylobacter spp. To investigate the heat tolerance of Salmonella enterica serovar Typhimurium DT104 in sausage-meat, chilled, handmade and frozen sausages were inoculated with approx. 1.5 x 10(4) bacterial cells per sausage (approximately 300 cfu g(-1)) and then cooked by frying, grilling or barbecuing. The levels of creatinine kinase, lactate dehydrogenase and alkaline phosphatase in uncooked and cooked sausages were measured to evaluate their potential as indicators of adequate cooking and, therefore, pathogen elimination. Salmonella were detected in 7.5% of frozen and 9.1% of the chilled sausages (8.6% overall) but Campylobacter spp. were not isolated. After cooking, a visual assessment suggested that all of the sausages were thoroughly cooked. Despite this, barbecuing and frying sometimes allowed Salmonella cells to survive and the temperature profiles during cooking indicated that the lethal range was sometimes not reached. The enzyme levels tested were not reliable indicators of the inactivation of bacterial pathogens because Salmonella were sometimes isolated from sausages with low values of all three enzymes. CONCLUSIONS: Salmonella spp. are present in a significant proportion of sausages and are not always killed during the cooking process. SIGNIFICANCE AND IMPACT OF THE STUDY: These findings have clear implications for public health.     

Comparative <Emphasis Type="Italic">in vivo</Emphasis> infection models yield insights on early host immune response to Campylobacter in chickens

Salmonella typhimurium and Campylobacter jejuni pose significant risks to human health and poultry are a major vector for infection. Comparative in vivo infection models were performed to compare the avian host immune response to both bacterial species. Forty-five commercial broiler chickens were orally challenged with either C. jejuni or S. typhimurium whilst 60 similar control birds were mock challenged in parallel. Birds were sacrificed at 0, 6, 20 and 48 h post-infection and cloacal swabs, blood and tissue samples taken. Peripheral blood leukocytes were isolated for flow cytometric analyses and RNA was extracted for gene expression profiling. Colonisation patterns were markedly different between the two bacterial species, with systemic colonisation of Campylobacter outside the gastrointestinal tract. Salmonella infection induced significant changes in circulating heterophil and monocyte/macrophage populations, whilst Campylobacter infection had no effect on the heterophil numbers but caused a significant early increase in circulating monocytes/macrophages. Toll-like receptor 1 (TLR1) gene expression was decreased, and avian β-defensin (AvBD) gene expression (AvBD3, AvBD10 and AvBD12) was significantly increased in response to Salmonella infection (P < 0.05). In contrast, Campylobacter infection induced increased TLR21 gene expression but significantly reduced expression of seven antimicrobial peptide (AMP) genes (AvBD3, AvBD4, AvBD8, AvBD13, AvBD14, CTHL2 and CTHL3; P < 0.05). Considered together, microbiological, cellular and gene expression profiles indicate that the innate immune system responds differently to Salmonella and to Campylobacter infection. Furthermore, reduction in the expression of AMPs may play a role in the persistence of high level colonisation of the host by Campylobacter. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Prevalence of bacterial faecal pathogens in separated and unseparated stored pig slurry

AIMS: To examine the prevalence and diversity of bacterial faecal pathogens in unseparated slurry, separated solids and liquid fractions from a commercial pig farm. METHODS: A total of 43 stored slurry specimens originating from a fattening house over the period February-April 2002 were analysed, consisting of unseparated (n = 14) slurry, separated solids (n = 16) and separated liquid (n = 13). Specimens were examined for the presence of five bacterial pathogens including Salmonella spp., Shigella spp., Campylobacter spp., Escherichia coli O157 and Yersinia enterocolitica. Selective enrichment and plating methods were employed for detection of Salmonella spp. and Campylobacter spp. and conventional selective plating techniques for the remaining genera. Antibiogram profiles to 12 antibiotic agents were obtained for all Salmonella isolates obtained. RESULTS: Salmonella spp. were identified in all components of the slurry specimens, whereas Campylobacter spp. was only recovered from the unseparated and separated liquid fractions. In both cases, the separated liquid fraction had the highest prevalence of pathogens and the separated solid fraction had the lowest prevalence. None of the slurry specimens examined were positive for E. coli O157:H7, Shigella spp. or Y. enterocolitica. Twenty-nine isolates of Salmonella were recovered from the slurry specimens, comprising seven serovars, of which Salmonella manhattan was the most prevalent, accounting for over half [15 of 29 (51.7%)] of all Salmonella isolates. Salmonella anatum, Salm. derby, Salm. give, Salm. heidelberg, Salm. simi and Salm. stanley serovars were also recovered. All Salmonella isolates were sensitive to ampicillin, augmentin (amoxicillin/clavulanic acid), chloramphenicol, ciprofloxacin, gentamicin, kanamycin and trimethoprim, but has variable resistance to tetracycline (100%), sulphonamides (84.6%), furazolidone (38.5%), nalidixic acid (15.4%) and streptomycin (15.4%). The majority (57.7%) of isolates displayed antibiotic resistance to at least two antibiotic agents, followed by 34.6% of isolates being resistant to three agents and the remainder (7.7%) being resistant to four antibiotics. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrated a marked reduction in the prevalence of Campylobacter and Salmonella in the solids component of separated pig slurry. The adoption of control processes such as aeration of slurry prior to its spread onto agricultural land and newer approaches to pathogen reduction should be investigated, to reduce the transmission of pathogens from pig slurry to the environment.     

Occurrence of Thermotolerant Campylobacter spp. on Eggshells: a Missing Link for Food-Borne Infections?

We analyzed the prevalence of thermotolerant Campylobacter spp. compared that of to Salmonella spp. in raw yolk and on eggshells. A total of 2,710 eggs were investigated for each bacterium. Viable bacteria were found in 4.1% (Campylobacter spp.) and 1.1% (Salmonella spp.) of the eggshell samples, whereas the egg yolk samples were negative for both bacteria.     

Fitness of antimicrobial-resistant Campylobacter and Salmonella

Campylobacter and Salmonella are the most commonly reported bacterial causes of human foodborne infections, and increasing proportions of these pathogens become resistant to medically important antimicrobial agents, imposing a burden on public health. Acquisition of resistance to antibiotics affects the adaptation and evolution of Salmonella and Campylobacter in various environments. Many resistance-conferring mutations entail a biological fitness cost, while others (e.g. fluoroquinolone resistance in Campylobacter) have no cost or even enhanced fitness. In Salmonella, the fitness disadvantage due to antimicrobial resistance can be restored by acquired compensatory mutations, which occur both in vitro and in vivo. The compensated or even enhanced fitness associated with antibiotic resistance may facilitate the spread and persistence of antimicrobial-resistant Salmonella and Campylobacter in the absence of selection pressure, creating a significant barrier for controlling antibiotic-resistant foodborne pathogens.     

Epidemiology and potential land-sea transfer of enteric bacteria from terrestrial to marine species in the Monterey Bay Region of California

Marine mammals are at risk for infection by fecal-associated zoonotic pathogens when they swim and feed in polluted nearshore marine waters. Because of their tendency to consume 25-30% of their body weight per day in coastal filter-feeding invertebrates, southern sea otters (Enhydra lutris nereis) can act as sentinels of marine ecosystem health in California. Feces from domestic and wildlife species were tested to determine prevalence, potential virulence, and diversity of selected opportunistic enteric bacterial pathogens in the Monterey Bay region. We hypothesized that if sea otters are sentinels of coastal health, and fecal pollution flows from land to sea, then sea otters and terrestrial animals might share the same enteric bacterial species and strains. Twenty-eight percent of fecal samples tested during 2007-2010 were positive for one or more potential pathogens. Campylobacter spp. were isolated most frequently, with an overall prevalence of 11%, followed by Vibrio cholerae (9%), Salmonella spp. (6%), V. parahaemolyticus (5%), and V. alginolyticus (3%). Sea otters were found positive for all target bacteria, exhibiting similar prevalences for Campylobacter and Salmonella spp. but greater prevalences for Vibrio spp. when compared to terrestrial animals. Fifteen Salmonella serotypes were detected, 11 of which were isolated from opossums. This is the first report of sea otter infection by S. enterica Heidelberg, a serotype also associated with human clinical disease. Similar strains of S. enterica Typhimurium were identified in otters, opossums, and gulls, suggesting the possibility of land-sea transfer of enteric bacterial pathogens from terrestrial sources to sea otters.     

Frequency of Escherichia coli O157:H7 isolation from stool specimens

During a 6-month period, 7252 faeces specimens were examined for Escherichia coli serotype O157:H7. Forty-nine specimens (0.7%) from 19 patients yielded this organism. Escherichia coli O157:H7 was the third most frequently isolated bacterial pathogen, following Campylobacter jejuni and (or) Salmonella sp. Although regional variation between laboratories determined whether Campylobacter jejuni or Salmonella was the primary bacterial pathogen isolated, E. coli O157:H7 was consistently isolated more frequently than either Shigella or Yersinia enterocolitica.     

Use of PCR for direct detection of Campylobacter species in bovine feces

This study reports on the use of PCR to directly detect and distinguish Campylobacter species in bovine feces without enrichment. Inhibitors present in feces are a major obstacle to using PCR to detect microorganisms. The QIAamp DNA stool minikit was found to be an efficacious extraction method, as determined by the positive amplification of internal control DNA added to bovine feces before extraction. With nested or seminested multiplex PCR, Campylobacter coli, C. fetus, C. hyointestinalis, and C. jejuni were detected in all fecal samples inoculated at approximately 10(4) CFU g(-1), and 50 to 83% of the samples inoculated at approximately 10(3) CFU g(-1) were positive. At approximately 10(2) CFU g(-1), C. fetus, C. hyointestinalis, and C. jejuni (17 to 50% of the samples) but not C. coli were detected by PCR. From uninoculated bovine feces, a total of 198 arbitrarily selected isolates of Campylobacter were recovered on four commonly used isolation media incubated at three temperatures. The most frequently isolated taxa were C. jejuni (152 isolates) and C. lanienae (42 isolates), but isolates of C. fetus subsp. fetus, Arcobacter butzleri, and A. skirrowii also were recovered (相似文献   

Prevalence of Salmonella spp., Campylobacter spp. and Listeria spp. in ring-billed gulls (Larus delawarensis).

Cloacal swabs collected from 264 ring-billed gulls (Larus delawarensis) at four sites near Montréal, Canada were cultured for the presence of Salmonella spp., Campylobacter spp. and Listeria spp. All birds were apparently healthy when captured or killed. Of all birds examined, 8.7%, 15.9% and 9.5%, respectively, were infected with Salmonella spp., Campylobacter spp. and Listeria monocytogenes. Overall, 29.9% of gulls sampled harbored one or more of these bacteria. Gulls probably play only a minor role in the epizootiology of these bacteria.     

Influence of host and bacteriophage concentrations on the inactivation of food-borne pathogenic bacteria by two phages

To use bacteriophages (phages) to control food-borne pathogenic bacteria, it will be necessary to determine the conditions allowing optimal activity. To start exploring these conditions, a Salmonella phage (P7) and a Campylobacter phage (Cj6) were incubated with their respective hosts at 24 °C for up to 2 h at varying phage and host cell concentrations, and surviving host cells were enumerated. A quadratic polynomial equation was fitted to the inactivation data and contour maps of inactivation against log₁₀ phage and host concentrations were plotted. Inactivation of Salmonella by P7 seemed to be independent of the host concentration, with close to 100% inactivation occurring at a phage concentration of around 5 × 10⁸ PFU mL⁻¹. For Campylobacter phage Cj6, there appeared to be an interaction of both phage and host concentrations. The data obtained were largely consistent with prior work indicating that, at low host cell concentrations, the proportion of cells killed is independent of the host cell concentration. The data indicate that biocontrol of pathogens present in low numbers in liquid foods is achievable, given a sufficiently high concentration of added phages, and that it is not necessary to know the concentration of pathogens to achieve this.     

Cladophora (Chlorophyta) spp. harbor human bacterial pathogens in nearshore water of Lake Michigan

Cladophora glomerata, a macrophytic green alga, is commonly found in the Great Lakes, and significant accumulations occur along shorelines during the summer months. Recently, Cladophora has been shown to harbor high densities of the fecal indicator bacteria Escherichia coli and enterococci. Cladophora may also harbor human pathogens; however, until now, no studies to address this question have been performed. In the present study, we determined whether attached Cladophora, obtained from the Lake Michigan and Burns Ditch (Little Calumet River, Indiana) sides of a breakwater during the summers of 2004 and 2005, harbored the bacterial pathogens Shiga toxin-producing Escherichia coli (STEC), Salmonella, Shigella, and Campylobacter. The presence of potential pathogens and numbers of organisms were determined by using cultural methods and by using conventional PCR, most-probable-number PCR (MPN-PCR), and quantitative PCR (QPCR) performed with genus- and toxin-specific primers and probes. While Shigella and STEC were detected in 100% and 25%, respectively, of the algal samples obtained near Burns Ditch in 2004, the same pathogens were not detected in samples collected in 2005. MPN-PCR and QPCR allowed enumeration of Salmonella in 40 to 80% of the ditch- and lakeside samples, respectively, and the densities were up to 1.6 x 10(3) cells per g Cladophora. Similarly, these PCR methods allowed enumeration of up to 5.4 x 10(2) Campylobacter cells/g Cladophora in 60 to 100% of lake- and ditchside samples. The Campylobacter densities were significantly higher (P < 0.05) in the lakeside Cladophora samples than in the ditchside Cladophora samples. DNA fingerprint analyses indicated that genotypically identical Salmonella isolates were associated with geographically and temporally distinct Cladophora samples. However, Campylobacter isolates were genetically diverse. Since animal hosts are thought to be the primary habitat for Campylobacter and Salmonella species, our results suggest that Cladophora is a likely secondary habitat for pathogenic bacteria in Lake Michigan and that the association of these bacteria with Cladophora warrants additional studies to assess the potential health impact on beach users.