A mixed outbreak of cryptosporidium and campylobacter infection associated with a private water supply

Small ruminants and zoonotic cryptosporidiosis

Sheep and goats are commonly infected with three Cryptosporidium species, including Cryptosporidium parvum, Cryptosporidium ubiquitum, and Cryptosporidium xiaoi, which differ from each in prevalence, geographic distribution, and public health importance. While C. parvum appears to be a dominant species in small ruminants in European countries, its occurrence in most African, Asian, and American countries appear to be limited. As a result, zoonotic infections due to contact with lambs and goat kids are common in European countries, leading to frequent reports of outbreaks of cryptosporidiosis on petting farms. In contrast, C. xiaoi is the dominant species elsewhere, and mostly does not infect humans. While C. ubiquitum is another zoonotic species, it occurs in sheep and goats at much lower frequency. Host adaptation appears to be present in both C. parvum and C. ubiquitum, consisting of several subtype families with different host preference. The host-adapted nature of C. parvum and C. ubiquitum has allowed the use of subtyping tools in tracking infection sources. This has led to the identification of geographic differences in the importance of small ruminants in epidemiology of human cryptosporidiosis. These tools have also been used effectively in linking zoonotic transmission of C. parvum between outbreak cases and the suspected animals. Further studies should be directly elucidating the reasons for differences in the distribution and public health importance of major Cryptosporidium species in sheep and goats.

Prevalence and genetic diversity of Campylobacter spp. in the production chain of broiler chickens in Lebanon and its association with the intestinal protozoan Blastocystis sp

Campylobacter jejuni is recognized as the most common foodborne pathogen associated with human gastroenteritis worldwide. Broilers are frequently infected by the bacteria and are considered the main source of exposure to humans. However, despite its public health impact, no recent data are currently available in Lebanon about Campylobacter spp. in poultry and human population. Therefore, this study aimed to determine the prevalence and genetic diversity of Campylobacter spp. in 227 ceca and on 227 carcasses of broiler chickens collected in Lebanese slaughterhouses. Overall, the prevalence of Campylobacter was shown to reach 67.0% in ceca and 17.2% on carcasses of Lebanese poultry. The only 2 Campylobacter species identified were C. jejuni and C. coli, with a slightly higher prevalence of C. coli in ceca and of C. jejuni on carcasses. A high level of genetic diversity was reported among the 51 C. jejuni isolates selected, since 25 distinct profiles were identified according to the comparative genomic fingerprinting typing method based on a subset of 40 genes using the 90% similarity threshold. Predominant clusters observed in Lebanese poultry isolates were also frequently found among French human clinical cases, highlighting that broiler chickens represent a potential reservoir for human campylobacteriosis. In addition, a significantly higher prevalence of Campylobacter spp. was found in slaughterhouse workers than in a cohort of hospitalized patients with no contact with poultry, confirming that contaminated broiler chickens in slaughterhouse appeared to be a non-negligible source of Campylobacter spp. transmission. Interestingly, a significant association between Campylobacter spp. and Blastocystis sp. has been observed. This correlation suggested that the presence of Campylobacter spp. would be favored when Blastocystis sp. is present and, similarly, the absence of one would favor the absence of the other. This is the first large-scale investigation focusing on the impact of Campylobacter spp. in broiler chickens in Lebanon and confirmed the need to implement prevention and control measures in the poultry production to reduce the burden of campylobacteriosis in the human population.

Risk Factors for Sporadic Domestically Acquired Campylobacter Infections in Norway 2010-2011: A National Prospective Case-Control Study

Background

Campylobacteriosis is the most frequently reported food- and waterborne infection in Norway. We investigated the risk factors for sporadic Campylobacter infections in Norway in order to identify areas where control and prevention measures could be improved.

Methods

A national prospective case-control study of factors associated with Campylobacter infection was conducted from July 2010 to September 2011. Cases were recruited from the Norwegian Surveillance System of Communicable Diseases (MSIS). Controls were randomly selected from the Norwegian Population Registry. Cases and controls were mailed a paper questionnaire with a prepaid return envelope. Univariable analyses using logistic regression were conducted for all exposures. A final parsimonious multivariable model was developed using regularized/penalized logistic regression, and adjusted odds ratios were calculated.

Results

A total of 995 cases and 1501 controls were included in the study (response proportion 55% and 30%, respectively). Exposures that had significant increases in odds of Campylobacter infection in multivariable analysis were drinking water directly from river, stream, or lake (OR: 2.96), drinking purchased bottled water (OR: 1.78), eating chicken (1.69), eating meat that was undercooked (OR: 1.77), eating food made on a barbecue (OR: 1.55), living on a farm with livestock (OR: 1.74), having a dog in the household (OR: 1.39), and having household water supply serving fewer than 20 houses (OR: 1.92).

Conclusions

Consumption of poultry and untreated water remain important sources of Campylobacter infection in Norway, despite ongoing control efforts. The results justify the need for strengthening education for consumers and food handlers about the risks of cross-contamination when preparing poultry and with consuming raw or undercooked chicken. The public should also be reminded to take precautions when drinking untreated water in nature and ensure continued vigilance in order to protect and maintain the quality of water from small-scale water supply systems.

Cryptosporidiosis outbreak in visitors of a UK industry-compliant petting farm caused by a rare Cryptosporidium parvum subtype: a case-control study

A case-control study was conducted to investigate an outbreak of 46 cases of cryptosporidiosis in visitors to a petting farm in England. Details of exposures on the farm were collected for 38 cases and 39 controls, recruited through snowball sampling. Multivariable logistic regression identified that cases were 5·5 times more likely than controls to have eaten without washing their hands [95% confidence interval (CI) 1·51–19·9, P = 0·01] and 10 times less likely to report being informed of risk of infection on arrival (odds ratio 0·10, 95% CI 0·01–0·71, P = 0·02). An uncommon Cryptosporidium parvum gp60 subtype (IIaA19G1R1) was identified in a lamb faecal sample and all subtyped cases (n = 22). We conclude that lack of verbal advice and non-compliance with hand washing are significantly associated with a risk of cryptosporidiosis on open farms. These findings highlight the public health importance of effectively communicating risk to petting farm visitors in order to prevent future outbreaks of zoonotic infections.

A national investigation of the prevalence and diversity of thermophilic Campylobacter species in agricultural watersheds in Canada

The occurrence and diversity of thermophilic Campylobacter species (C. jejuni, coli, and lari) were studied in water samples from four river basins located across Canada. These basins located in Quebec (Bras d'Henri), Alberta (Oldman), Ontario (South Nation), and British Columbia (Sumas) represented some of the most intensive farming areas in Canada for hog, beef cattle, dairy cattle, and poultry, respectively. This study analyzed 769 water samples collected from 23 monitoring sites with agricultural influence, and four reference sites with limited or no agricultural influence. Water samples were collected bi-weekly over two years and analyzed for Campylobacter using a semi-quantitative minimum probable number (MPN) enrichment protocol. Putative isolates were confirmed by genus- and species-specific multiplex polymerase chain reaction (PCR) assays. A total of 377 (49%) water samples were positive for campylobacters with 355 samples having a cell density ranging from 4 to 4000 MPN L(-1). Campylobacters were more common at agricultural than reference sites in each river basin, although this difference was not significant in the Oldman and South Nation (p > 0.05). Campylobacter was significantly more common in the Bras d'Henri and Sumas (63%) compared to the South Nation (45%) and Oldman (33%) River basins (p < 0.05). C. jejuni, C. coli and C. lari were detected in each river basin, and these species occurred in 45% (n = 168), 34% (n = 128) and 19% (n = 73), of all Campylobacter positive samples, respectively. The remaining Campylobacter positive water samples without these three species (n = 67; 18%) were identified as other Campylobacter species. C. jejuni was the predominant species occurring in the Sumas, Oldman and South Nation River basins. However, in the Bras d'Henri River basin with intensive hog production, C. coli was the predominant species. This study found campylobacters to be common in some agricultural systems with intensive livestock farming activities, and different river basins could have strikingly different profiles of either C. jejuni or C. coli as the predominant waterborne thermophilic Campylobacter species.

Prevalence and determinants of Campylobacter infection among under five children with acute watery diarrhea in Mwanza, North Tanzania

BACKGROUND

Campylobacteriosis, a zoonotic bacterial disease observed world-wide, is becoming the most commonly recognized cause of bacterial gastroenteritis in humans. This study was done to determine the prevalence and determinants of Campylobacter infection among under-fives with acute watery diarrhea in Mwanza City, Tanzania.

METHOD

This cross-sectional hospital-based study was conducted at Bugando Medical Centre (BMC) and Sekou Toure Hospital in Mwanza City. All inpatients and outpatients under-fives who met the inclusion criteria from October 2012 to April 2013 were enrolled in the study. Demographic and clinical data were obtained using standardized data collection tools. Stool samples were collected for gram staining and culture for Campylobacter spp. on Preston selective agar media. In addition, blood slides for malaria and HIV tests were done to all patients.

RESULTS

A total of 300 children were enrolled with a median age of 12 [interquartile range, 8-19] months. Of these, 169 (56.5%) were from BMC and 131 (43.7%) from Sekou-Toure hospital. One hundred and seventy (56.7%) of the participating children were male. Of 300 under-fives with acute watery diarrhea, 29 patients (9.7%) were found to have Campylobacter infection. A significant higher number of children with Campylobacter infection were found in Sekou Toure hospital compared to BMC [16.0% (21/29) versus 4.7% (8/29), p = 0.002)]. Age above 2 years was independently found to predict campylobacter infection (OR: 2.9, 95% CI 1.1-7.7, p = 0.0037). Of 30 patients with a positive blood slide for Plasmodium falciparum, 20.0% were also positive for Campylobacter infection (OR: 3.9, 95% CI 1.2-10.1, p = 0.021).

CONCLUSION

Campylobacter infection shows a comparatively low prevalence in under-fives with acute watery diarrhea in Mwanza city and is independently associated with positive slides for malaria and an age above 2 years. Further studies are needed to type the most prevalent Campylobacter species and to determine their antibiotic susceptibility pattern.

An evaluation of SaTScan for the prospective detection of space-time Campylobacter clusters in the North East of England

Campylobacteriosis is the commonest cause of bacterial enteritis in England yet the epidemiology of apparently sporadic cases is not well understood. Here we evaluated the feasibility of applying a space-time cluster detection method to routine laboratory surveillance data in the North East of England by simulating prospective weekly space-time cluster detection using SaTScan as if it had been performed for 2008-2011. From the 209 simulated weekly runs using a circular window, 20 distinct clusters were found which contained a median of 30 cases (interquartile range 15-66) from a median population of ~134,000 persons. This corresponds to detection of a new cluster every 10 weeks. We found significant differences in age, sex and deprivation score distributions between areas within clusters compared to those without. The results of this study suggest that space-time detection of Campylobacter clusters could be used to find groups of cases amenable to epidemiological investigation.

Effect of temperature and antimicrobial resistance on survival of Campylobacter jejuni in well water: application of the Weibull model

AIMS

The aims of this study were to measure the survival of two Campylobacter jejuni strains and their in vitro-challenged antimicrobial-resistant variants in well water, to evaluate the effects of antimicrobial resistance on survival and to develop a mathematical model for predicting the survival of Camp. jejuni in well water in the temperature range from 4 to 25°C.

METHODS AND RESULTS

The survival in log CFU ml⁻¹ of two Camp. jejuni strains and their antimicrobial-resistant variants was studied in well water stored at 4, 10, 15, 20 and 25°C. At 4°C, the estimated 4-log CFU ml⁻¹ decrease in ciprofloxacin-resistant variant ATCC33560CIP32 was 55·2 days, significantly longer (P < 0·05) than that of resistant variant 49/7RATCIP32 (the estimated 4-log CFU ml⁻¹ decrease was 29·9 days). The respective times for the wild-type strains were 49·8 and 60·4 days. The decrease in counts of Camp. jejuni was most dependent on temperature, because at 4°C, the estimated t (4D) varied from 29·9 to 60·4 days and at 25°C from 3·7 to 5·7 days.

CONCLUSIONS

Campylobacter jejuni survived in well water for long periods, especially at 4°C, and the effect of ciprofloxacin resistance on fitness and survival was strain and temperature dependent. Weibull model was found to fit the data in the temperatures from 4 to 25°C.

SIGNIFICANCE AND IMPACT OF THE STUDY

In water environment Camp. jejuni is exposed to a wide spectrum of temperatures, which affects its survival and potential to cause waterborne infections. Antimicrobial resistance in Camp. jejuni is increasing, and minor data exist on the effect of antimicrobial resistance on the survival of Camp. jejuni. Water is an important source of campylobacteriosis; thus, we need to have modelling data to predict the survival characteristics of these organisms in water.

Zoonotic cryptosporidiosis in the UK - challenges for control

The protozoan parasite Cryptosporidium infects all classes of vertebrates. Of the major human pathogenic species, Cryptosporidium parvum and Cryptosporidium hominis predominate in the UK. Cryptosporidium hominis is a human-adapted species, while C. parvum has many animal hosts and is particularly common in preweaned farmed ruminants. Evaluation of zoonotic risks has been provided mainly by descriptive and analytical epidemiological studies and enhanced recently by genetic typing of isolates. The robust nature of the transmissive oocyst stage, multiple transmission routes, lack of antiparasitic treatment options and vaccines, and resistance to chlorine disinfection present challenges for control. Subtyping C. parvum isolates has been used to link human cases and suspected sources of infection in sporadic cases and outbreaks. Although it is possible that all C. parvum isolates are potentially zoonotic, populations with and without farm animal linkage have been identified. New zoonotic risks have emerged in at least one outbreak, caused by the Cryptosporidium sp. rabbit genotype. This re-enforces the need to characterize infecting and contaminating isolates to ensure appropriate interventions. This study describes the risks of zoonotic cryptosporidiosis by detailing the hosts providing a potential reservoir, the risks of transmission to humans, outbreaks in animal-associated settings and guidance for control with special emphasis on the UK.

Campylobacter spp. as a Foodborne Pathogen: A Review

Campylobacter is well recognized as the leading cause of bacterial foodborne diarrheal disease worldwide. Symptoms can range from mild to serious infections of the children and the elderly and permanent neurological symptoms. The organism is a cytochrome oxidase positive, microaerophilic, curved Gram-negative rod exhibiting corkscrew motility and is carried in the intestine of many wild and domestic animals, particularly avian species including poultry. Intestinal colonization results in healthy animals as carriers. In contrast with the most recent published reviews that cover specific aspects of Campylobacter/campylobacteriosis, this broad review aims at elucidating and discussing the (i) genus Campylobacter, growth and survival characteristics; (ii) detection, isolation and confirmation of Campylobacter; (iii) campylobacteriosis and presence of virulence factors; and (iv) colonization of poultry and control strategies.

Campylobacter epidemiology: an aquatic perspective

Members of the genus Campylobacter have established themselves as the most common human gastro-enteric pathogens throughout much of the developed world. The ubiquitous distribution of Campylobacter spp. in animal reservoirs and food products derived thereof make such vehicles primary risk factors in contracting campylobacteriosis. The contamination rates, identification of common pathogenic serotypes and extended survival of Campylobacter in surface waters illustrates the potential, but yet to be quantified, campylobacteriosis risk associated with untreated water. The existence and potential pathogenicity of viable but nonculturable forms of Campylobacter remains a contentious subject. Furthermore, the role of such forms in the epidemiology of Campylobacter related disease and their involvement in the large number of waterborne gastroenteritis outbreaks from which a disease agent cannot be isolated remains to be fully clarified. This article presents a survey of current perspectives with regard to the survival and epidemiology of Campylobacter spp. in natural water systems.

The epidemiology of sporadic human infections with unusual cryptosporidia detected during routine typing in England and Wales, 2000-2008

Routine typing of 14 469 isolates from human cryptosporidiosis cases between 2000 and 2008 revealed that 7439 (51·4%) were Cryptosporidium (C.) hominis, 6372 (44·0%) C. parvum, 51 (0·4%) both C. hominis and C. parvum, 443 (3·1%) were not typable and 164 (1·1%) were other Cryptosporidium species or genotypes. Of the latter, 109 were C. meleagridis, 38 C. felis, 11 C. ubiquitum, one C. canis, two horse, two novel and one skunk genotype. C. hominis monkey genotype and C. cuniculus were identified in a separate study. Patients with unusual infections were older than those with C. hominis (P<0·01) or C. parvum (P<0·01) and were more likely to be immunocompromised (Fisher's exact P<0·01). Forty-one percent of unusual cases had travelled abroad, mainly to the Indian subcontinent. Significant risk factors in those with unusual species were travel abroad (C. meleagridis, P<0·01), being immunocompromised (C. felis, Fisher's exact P=0·02), and contact with cats (C. felis, Fisher's exact P=0·02).

Temporal and farm-management-associated variation in the faecal-pat prevalence ofCampylobacter jejuniin ruminants

In a 2-year longitudinal study of adult animals on 15 dairy farms and four sheep farms in Lancashire, UK.C. jejuniwas isolated from all farms, although not on every occasion. Faecal samples were collected and cultured using standard techniques for isolation ofCampylobacter. Assignment to species was via PCR assays. Peak prevalence ofC. jejuniin both cattle and sheep was observed during the summer and in cattle this apparent seasonality was associated with grazing pasture [odds ratio (OR) 2·14], while in sheep it was independent of grazing. Increased prevalence was associated with increased milk yield (OR 1·05) and herd size (OR 1·01) in dairy cattle, and with increased stocking density (OR 1·29) and pasture quality (OR 2·16) in sheep. There was considerable variation in prevalence between farms but no evidence of large-scale spatial variation. The association betweenC. jejuniprevalence and diet in dairy cattle deserves further investigation.

Water privatization, water source, and pediatric diarrhea in Bolivia: epidemiologic analysis of a social experiment

Water and sanitation services are fundamental to the prevention of pediatric diarrhea. To enhance both access to water and investment, some argue for the privatization of municipal water networks. Water networks in multiple Bolivian cities were privatized in the 1990s, but contracts ended following popular protests citing poor access. A population-based retrospective cohort study was conducted in two Bolivian cities. Data were collected on family water utilization and sanitation practices and on the prevalence of diarrhea among 596 children. Drinking from an outdoor water source (OR, 2.08; 95%CI, 1.25-3.44) and shorter in-home water boiling times (OR, 1.99; 95%CI, 1.19-3.34) were associated with prevalence of diarrhea. Increased prevalence was also observed for children from families using private versus public water services, using off-network water from cistern trucks, or not treating their water in-home. Results suggest that water source, water provider, and in-home water treatment are important predictors of pediatric diarrhea.

GiardiaandCryptosporidiuminfections in sheep and goats: a review of the potential for transmission to humans via environmental contamination

The public health significance of giardiasis and cryptosporidiosis in sheep is currently unclear. Some research suggests that they are probably not an important zoonotic reservoir, whilst other research indicates this potential exists, and some outbreaks have also been associated with infections in sheep. Actions to limit water supply contamination by sheep have sometimes been severe, occasionally creating problems between farming and public health communities. Here our knowledge on these parasites in both sheep and goats is reviewed; although direct evidence of transmission to humans via water supply contamination is limited, the data accrued indicate that this is a real possibility. As cryptosporidiosis in sheep is generally more prevalent than giardiasis, and species/genotypes ofCryptosporidiuminfections in sheep are likely to be infectious to humans, this parasite may be considered the greater threat. Nevertheless, geographical variation in prevalence and genotypic distribution is extensive and as measures to limit sheep grazing can have a highly negative impact, it is important that cases are judged individually. If water contamination from a particular population of sheep/goats is suspected, then suitable investigations should be instigated, investigating both prevalence and species/genotype, before precautionary measures are imposed.

Behaviour of Campylobacter jejuni in experimentally contaminated bottled natural mineral water

AIMS

The main objective of the present study was to estimate the survival of microaerophilic Campylobacter jejuni in filtered natural mineral water at 4 degrees C and 25 degrees C. The influence of the presence of biodegradable organic matter was tested, assuming that the bacterial contamination of a bottled natural mineral water could be associated with contamination by organic matter.

METHODS AND RESULTS

Washed Campylobacter cultures were inoculated in natural mineral water and sterile natural mineral water, and incubated in the dark at 4 degrees C and 25 degrees C. The effect of temperature, the biodegradable organic matter added, incubation atmosphere and autochthonous microflora were tested on the cultivability of Camp. jejuni.

CONCLUSIONS

The survival of Camp. jejuni in natural mineral water was better at 4 degrees C than at 25 degrees C, and the presence of organic matter led to a deceleration in the loss of cultivability and to the multiplication of Camp. jejuni in natural mineral water.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study highlighted the fact that, in the event of dual contamination of a bottled natural mineral water (Campylobacter and biodegradable organic matter), the pathogen could survive (and even grow) for a relatively long time, especially at low temperature and in spite of the presence of oxygen.

Specific detection of Campylobacter jejuni from faeces using single nucleotide polymorphisms

Specimens of human faeces were tested by a rapid strategy for detection of Campylobacter jejuni lineages by the presence of specific single nucleotide polymorphisms (SNPs) based on the C. jejuni multi locus sequence typing (MLST) scheme. This strategy was derived from analysis of the MLST databases to identify clonal complex specific SNPs followed by the design of real-time PCR assays to enable identification of six major C. jejuni clonal complexes associated with cases of human infection. The objective was to use the MLST SNP-based assays for the direct detection of C. jejuni by clonal complex from specimens of human faeces, and then confirm the accuracy of the clonal complex designation from the SNP-based assays by performing MLST on the cultured faecal material, this targeted at determining the validity of direct molecular specimen identification. Results showed it was possible to identify 38% of the isolates to one of the six major MLST clonal complexes using a rapid DNA extraction method directly from faeces in under 3 h. This method provides a novel strategy for the use of real-time PCR for detection and characterization beyond species level, supplying real-time epidemiological data, which is comparable with MLST results.

Outbreaks of waterborne infectious intestinal disease in England and Wales, 1992-2003

We reviewed the epidemiological and microbiological characteristics of 89 reported outbreaks of waterborne infectious intestinal disease affecting 4321 people in England and Wales over the period 1992-2003. Public water supplies were implicated in 24 outbreaks (27%), private water supplies in 25 (28%), swimming pools in 35 (39%) and other sources in five outbreaks (6%). Cryptosporidium was implicated in 69% of outbreaks, Campylobacter sp. in 14%, Giardia in 2%, E. coli O157 in 3% and Astrovirus in 1%. From 2000, there was a consistent decline in the number of outbreaks of waterborne disease associated with public water supplies. The incidence rate of outbreaks in recipients of private water supplies may be as high as 35 times the rate in those receiving public water supplies (1830 vs. 53 per million population). Private water suppliers need to be aware of the importance of adequate treatment and the prevention of faecal contamination of storage water. Swimming-pool operators need to ensure chlorination and in particular adequate filtration measures are in place.

New genotypes and factors associated with Cryptosporidium detection in mussels (Mytilus spp.) along the California coast

A 3 year study was conducted to evaluate mussels as bioindicators of faecal contamination in coastal ecosystems of California. Haemolymph samples from 4680 mussels (Mytilus spp.) were tested for Cryptosporidium genotypes using PCR amplification and DNA sequence analysis. Our hypotheses were that mussels collected from sites near livestock runoff or human sewage outflow would be more likely to contain the faecal pathogen Cryptosporidium than mussels collected distant to these sites, and that the prevalence would be greatest during the wet season when runoff into the nearshore marine environment was highest. To test these hypotheses, 156 batches of sentinel mussels were collected quarterly at nearshore marine sites considered at higher risk for exposure to livestock runoff, higher risk for exposure to human sewage, or lower risk for exposure to both faecal sources. Cryptosporidium genotypes detected in Haemolymph samples from individual mussels included Cryptosporidium parvum, Cryptosporidium felis, Cryptosporidium andersoni, and two novel Cryptosporidium spp. Factors significantly associated with detection of Cryptosporidium spp. in mussel batches were exposure to freshwater outflow and mussel collection within a week following a precipitation event. Detection of Cryptosporidium spp. was not associated with higher or lower risk status for exposure to livestock faeces or human sewage sources. This study showed that mussels can be used to monitor water quality in California and suggests that humans and animals ingesting faecal-contaminated water and shellfish may be exposed to both host-specific and anthropozoonotic Cryptosporidium genotypes of public health significance.

Evaluation of antimicrobial susceptibility patterns inCampylobacterspp isolated from dairy cattle and farms managed organically and conventionally in the midwestern and northeastern United States

OBJECTIVE

To describe antimicrobial susceptibility patterns in Campylobacter spp isolated from dairy cattle and farms managed organically and conventionally in the midwestern and northeastern United States.

DESIGN

Longitudinal study.

SAMPLE POPULATION

128 farms.

PROCEDURE

Samples and data were collected every 2 months from August 2000 to October 2001. Fecal samples were collected from calves and cows. Milk samples were obtained from the bulk tank and milk line filters. Environmental samples were obtained from a water source, feed bunks of lactating cows, and cattle housing areas. Campylobacter identification and antimicrobial susceptibility testing were performed at a central laboratory by use of microbroth dilution with 2 customized antimicrobial susceptibility panels.

RESULTS

460 and 1,570 Campylobacter isolates were obtained from organic and conventional dairy farms, respectively. Most isolates from both farm types were susceptible to most antimicrobial agents tested, and antimicrobial susceptibility of conventional dairy isolates was decreased, compared with organic dairy isolates. Low proportions of isolates resistant to ampicillin (< 10%) and moderate proportions resistant (30% to 60%) to kanamycin, sulfamethoxazole, and tetracycline were observed on both farm types. The proportion of isolates resistant to tetracycline was higher for conventional than organic farms.

CONCLUSIONS AND CLINICAL RELEVANCE

Campylobacter isolates from dairy cattle and farms managed organically and conventionally had similar patterns of antimicrobial resistance; the proportion of resistant isolates was higher for conventional than organic farms.

Genetic mechanisms contributing to reduced tetracycline susceptibility of Campylobacter isolated from organic and conventional dairy farms in the midwestern and northeastern United States

Campylobacter is one of the most common causes of gastroenteritis and can be acquired through contact with farm animals or the consumption of raw milk. Because of concerns over the role of food-producing animals in the dissemination of antimicrobial resistance to humans, we evaluated the prevalence of antimicrobial resistance in Campylobacter isolates from dairy farms and the genetic mechanism conferring the observed resistance. Evaluation of antimicrobial resistance was completed on 912 isolates from conventional and 304 isolates from organic dairy farms to eight drugs (azithromycin, chloramphenicol, ciprofloxacin, clindamycin, erythromycin, gentamicin, nalidixic acid, and tetracycline) with microbroth dilution. Resistance to seven of eight drugs was very low and did not differ by farm type. However, tetracycline resistance was common in Campylobacter isolated from both organic and conventional dairy farms, with 48 and 58% of isolates affected, respectively. By multiplex PCR, we determined that tetracycline resistance was highly associated with the carriage of tetO in Campylobacter isolates (X2 = 124, P < 0.01, kappa = 0.86).

Spatial epidemiology and natural population structure of Campylobacter jejuni colonizing a farmland ecosystem

Recent progress in determining the population structure of Campylobacter jejuni, and discerning associations between genotypes and specific niches, has emphasized the shortfall in our understanding of the ecology and epidemiology of this bacterium. We examined the natural structure of the C. jejuni community associated with cattle farmland in the UK by structured spatiotemporal sampling of habitats, including livestock and wild animal faeces, environmental water and soil, over a 10-week period within a 100 km2 area. A total of 172 isolates were characterized using multilocus sequence typing into 65 sequence types (STs). Isolates from cattle faeces were significantly over-represented in the ST-61 complex, whereas isolates from wildlife faeces and water were more likely to belong to the ST-45 complex and a number of unusual STs, many of which were first encountered during this study. Sampling within a narrow spatiotemporal window permitted the application of novel statistical methods exploring the relationship between the genetic relatedness and spatial separation of isolates. This approach showed that isolates from the same sampling squares and squares separated by <1.0 km were genetically more similar than isolates separated by greater distances. Our study demonstrates the potential of multilocus sequence typing combined with spatial modelling in exploring natural transmission pathways for C. jejuni.

Frequency and spatial distribution of environmental Campylobacter spp

Humans are exposed to Campylobacter spp. in a range of sources via both food and environmental pathways. For this study, we explored the frequency and distribution of thermophilic Campylobacter spp. in a 10- by 10-km square rural area of Cheshire, United Kingdom. The area contains approximately 70, mainly dairy, farms and is used extensively for outdoor recreational activities. Campylobacter spp. were isolated from a range of environmental samples by use of a systematic sampling grid. Livestock (mainly cattle) and wildlife feces and environmental water and soil samples were cultured, and isolates were presumptively identified by standard techniques. These isolates were further characterized by PCR. Campylobacter jejuni was the most prevalent species in all animal samples, ranging from 11% in samples from nonavian wildlife to 36% in cattle feces, and was isolated from 15% of water samples. Campylobacter coli was commonly found in water (17%) and sheep (21%) samples, but rarely in other samples. Campylobacter lari was recovered from all sample types, with the exception of sheep feces, and was found in moderate numbers in birds (7%) and water (5%). Campylobacter hyointestinalis was only recovered from cattle (7%) and birds (1%). The spatial distribution and determinants of C. jejuni in cattle feces were examined by the use of model-based spatial statistics. The distribution was consistent with very localized within-farm or within-field transmission and showed little evidence of any larger-scale spatial dependence. We concluded that there is a potentially high risk of human exposure to Campylobacter spp., particularly C. jejuni, in the environment of our study area. The prevalence and likely risk posed by C. jejuni-positive cattle feces in the environment diminished as the fecal material aged. After we took into account the age of the fecal material, the absence or presence of rain, and the presence of bird feces, there was evidence of significant variation in the prevalence of C. jejuni-positive cattle feces between grazing fields but no evidence of spatial clustering beyond this resolution. The spatial pattern of C. jejuni is therefore consistent with that for an organism that is ubiquitous in areas contaminated with cattle feces, with a short-scale variation in infection intensity that cannot be explained solely by variations in the age of the fecal material. The observed pattern is not consistent with large-scale transmission attributable to watercourses, wildlife territories, or other geographical features that transcend field and farm boundaries.

Characterization of waterborne outbreak-associated Campylobacter jejuni, Walkerton, Ontario

The Walkerton, Canada, waterborne outbreak of 2000 resulted from entry of Escherichia coli O157:H7 and Campylobacter spp. from neighboring farms into the town water supply. Isolates of Campylobacter jejuni and Campylobacter coli obtained from outbreak investigations were characterized by phenotypic and genotypic methods, including heat-stable and heat-labile serotyping, phage typing, biotyping, fla–restriction fragment length polymorphism (RFLP) typing, and pulsed-field gel electrophoresis. Two main outbreak strains were identified on the basis of heat-stable serotyping and fla-RFLP typing. These strains produced a limited number of types when tested by other methods. Isolates with types indistinguishable from, or similar to, the outbreak types were found only on one farm near the town of Walkerton, whereas cattle from other farms carried a variety of Campylobacter strains with different type characteristics. Results of these analyses confirmed results from epidemiologic studies and the utility of using several different typing and subtyping methods for completely characterizing bacterial populations.

Cattle and sheep farms as reservoirs of Campylobacter

AIM

This is a review of the natural Campylobacter colonization and transmission among ruminant livestock in the dairy farm environment.

METHODS AND RESULTS

Using cultural detection methods and enumeration techniques the distribution of Campylobacter in ruminant animals at birth, on the farm, at slaughter and in the farm environment have been examined. Colonization and shedding rates are higher among young animals while patterns of shedding in adult animals may be seasonal. Stored and land-dispersed slurries provide a reservoir for scavenging birds and flies and a source for runoff.

CONCLUSIONS

The dairy farm plays a significant role in the dissemination of Campylobacter subtypes that can cause disease in the human community.

SIGNIFICANCE AND IMPACT OF STUDY

An understanding of the role of the dairy farm in the environmental cycle of Campylobacter is required in order to devise intervention strategies.

Clonal complexes of Campylobacter jejuni identified by multilocus sequence typing correlate with strain associations identified by multilocus enzyme electrophoresis

Multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) with SmaI were used to subtype 55 isolates of Campylobacter jejuni from a diverse range of human and animal sources previously characterized by multilocus enzyme electrophoresis (MEE). MEE and MLST targeted 11 and 7 loci, respectively, and all loci were unique to each method. MEE, MLST, and PFGE identified 40, 37, and 48 discrete subtypes, respectively, with many of the subtypes occurring only once within the data set. Simpson's indices of diversity were calculated to be 0.979, 0.966, and 0.994 for MEE, MLST, and PFGE, respectively, demonstrating that MEE and MLST had similar discriminatory powers but that PFGE was more discriminatory. Allele diversity was higher in the MLST loci; individual single-locus diversities for the 11 MEE loci and the 7 MLST loci were 0.491 and 0.854, respectively. The clonal complexes recognized by MLST correlated with the strain associations previously recognized by MEE and contained some isolates indistinguishable by PFGE. Many clusters contained isolates from diverse geographical regions and from both humans and animals. These results demonstrate the usefulness of MLST for investigation of the global epidemiology of this important pathogen and illustrate its potential to identify indistinguishable strains or clones in geographically distinct regions.

Culturability, injury and morphological dynamics of thermophilic Campylobacter spp. within a laboratory-based aquatic model system

AIMS

To study the survival processes of thermophilic Campylobacter spp. within a modelled aquatic system and particularly the involvement and survival potential of viable but non-culturable forms.

METHODS AND RESULTS

The survival and morphological characteristics of populations of thermophilic Campylobacter species exposed to simulated aquatic conditions were examined using a combination of cultural and microscopic techniques. Populations underwent progressive decay when exposed to simulated aquatic conditions. The rates of population decay were observed to be significantly greater at the higher temperature (20 degrees C) with a rapid transition of the dominant sub-populations from non-stressed to dead cells occurred within 3 days. At 10 degrees C the rate of culturability loss was much reduced with substantial development (approx. 80% of total population) of viable but non-culturable (VBNC) populations by all species within 3 days, declining to represent approximately 5-25% of the total population at day 60. Significant differences (P < 0.001) were identified between decay rates as a consequence of different species, sub-populations and temperature but not between sub-populations of different species. Morphological variants including spiral, elongated spirals and rods, short rods and coccoid forms were identified. The endpoints of morphological transition were temperature-independent and isolate-specific yet the rate of morphological transition was directly related to temperature and approximately equivalent between species.

CONCLUSION

The VBNC state is a transitory stage in the degeneration of Campylobacter population within the aquatic environments simulated during this study.

SIGNIFICANCE AND IMPACT OF THE STUDY

VBNC cells form the most persistent, viable, potentially pathogenic sub-population of Campylobacter populations exposed to aquatic stress conditions.

Gastrointestinal infections

Advances in public health have reduced the risk of contracting certain enteric diseases, but many remain, and new pathogens have emerged and/or recently have been discovered. The pathogenic agents are varied and consist of a variety of bacteria and select viruses and parasites. Selected use of microbiologic assays to detect these pathogens is encouraged. When tests are ordered non-judiciously, costs rapidly accrue. The age of the patient, time of year, travel history, and clinical presentation all provide clues to the etiologic agent. Microbiologic assays should be used judiciously to confirm or exclude the likely infectious agents.

Efficacy of iodine water purification tablets against Cryptosporidium oocysts and Giardia cysts

The ability to control water-borne diseases is critical for soldiers, hikers, and others who may need to drink directly from an outdoor source. Water-borne protozoan parasites that are specifically of concern are Giardia and Cryptosporidium because of their resistance to halogen disinfection. The purpose of this study was to determine the effectiveness of iodine tablets against Giardia and Cryptosporidium under general- and worst-case water conditions that might be found in the field. Giardia cysts and Cryptosporidium oocysts were exposed to iodine according to manufacturer's instructions (two tablets/L = 13-18 mg/L for 20 minutes). This dose inactivated 3-log10 of Giardia in general-case water and pH 9. In worst-case water, however, only about 35% of cysts were inactivated at pH 5. Fifty minutes were required to achieve a 3-log10 reduction at pH 5. Cryptosporidium oocysts were more difficult to inactivate. Only 10% were inactivated after a 20-minute exposure to iodine according to manufacturer's instructions; even after 240 minutes of exposure to iodine only 66-81% oocysts were inactivated. These data strongly suggest that iodine disinfection is not effective in inactivating Cryptosporidium oocysts in water. Because this organism is common in all surface waters, it is recommended that another method of treatment be used before ingestion.