Serotypes and Virulence Gene Profiles of Shiga Toxin-Producing Escherichia coli Strains Isolated from Feces of Pasture-Fed and Lot-Fed Sheep

Shiga toxin-producing Escherichia coli (STEC) strains possessing genes for enterohemolysin (ehxA) and/or intimin (eae), referred to here as complex STEC (cSTEC), are more commonly recovered from the feces of humans with hemolytic uremic syndrome and hemorrhagic colitis than STEC strains that do not possess these accessory virulence genes. Ruminants, particularly cattle and sheep, are recognized reservoirs of STEC populations that may contaminate foods destined for human consumption. We isolated cSTEC strains from the feces of longitudinally sampled pasture-fed sheep, lot-fed sheep maintained on diets comprising various combinations of silage and grain, and sheep simultaneously grazing pastures with cattle to explore the diversity of cSTEC serotypes capable of colonizing healthy sheep. A total of 67 cSTEC serotypes were isolated, of which 21 (31.3%), mainly isolated from lambs, have not been reported. Of the total isolations, 58 (86.6%) were different from cSTEC serotypes isolated from a recent study of longitudinally sampled healthy Australian cattle (M. Hornitzky, B. A. Vanselow, K. Walker, K. A. Bettelheim, B. Corney, P. Gill, G. Bailey, and S. P. Djordjevic, Appl. Environ. Microbiol. 68:6439-6445, 2002). Our data suggest that cSTEC serotypes O5:H⁻, O75:H8, O91:H⁻, O123:H⁻, and O128:H2 are well adapted to colonizing the ovine gastrointestinal tract, since they were the most prevalent serotypes isolated from both pasture-fed and lot-fed sheep. Collectively, our data show that Australian sheep are colonized by diverse cSTEC serotypes that are rarely isolated from healthy Australian cattle.     

The diversity of Escherichia coli serotypes and biotypes in cattle faeces

AIM: To study the diversity of commensal Escherichia coli populations shed in faeces of cattle fed on different diets. METHODS AND RESULTS: Thirty Brahman-cross steers were initially fed a high grain (80%) diet and then randomly allocated into three dietary treatment groups, fed 80% grain, roughage, or roughage + 50% molasses. Up to eight different E. coli isolates were selected from primary isolation plates of faecal samples from each animal. Fifty-two distinct serotypes, including nine different VTEC strains, were identified from a total of 474 E. coli isolates. Cattle fed a roughage + molasses diet had greater serotype diversity (30 serotypes identified) than cattle fed roughage or grain (21 and 17 serotypes identified respectively). Cluster analysis showed that serotypes isolated from cattle fed roughage and roughage + molasses diets were more closely associated than serotypes isolated from cattle fed grain. Resistance to one or more of 11 antimicrobial agents was detected among isolates from 20 different serotypes. Whilst only 2.3% of E. coli isolates produced enterohaemolysin, 25% were found to produce alpha-haemolysin. CONCLUSIONS: Diverse non-VTEC populations of E. coli serotypes are shed in cattle faeces and diet may affect population diversity. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides new information on the serotype diversity and phenotypic traits of predominant E. coli populations in cattle faeces, which could be sources of environmental contamination.     

Virulence genes and intimin types of Shiga-toxin-producing Escherichia coli isolated from cattle and beef products in Argentina.

A total of 153 Shiga-toxin-producing Escherichia coli (STEC) isolates from feces of cattle and beef products (hamburgers and ground beef) in Argentina were characterized in this study. PCR showed that 22 (14%) isolates carried stx1 genes, 113 (74%) possessed stx2 genes and 18 (12%) both stx1 and stx2. Intimin (eae), enterohemolysin (ehxA), and STEC autoagglutinating adhesin (saa) virulence genes were detected in 36 (24%), 70 (46%) and in 34 (22%) of the isolates, respectively. None of 34 saa-positive isolates carried the gene eae, and 31 were ehxA-positive. Fourteen (7 of serotype O26:H11 and 4 of serotype O5:H-) isolates had intimin b1, 16 isolates possessed intimin g1 (11 of serotype O145:H- and 5 of serotype O157:H7), 5 isolates had intimin type e1 (4 of serotypes O103:H- and O103:H2), and one isolate O111:H- showed intimin type q/g2. Although the 153 STEC isolates belonged to 63 different seropathotypes, only 12 accounted for 58% of isolates. Seropathotype ONT:H- stx2 (18 isolates) was the most common, followed by O171:H2 stx2 (12 isolates), etc. The majority (84%) of STEC isolates belonged to serotypes previously found in human STEC and 56% to serotypes associated with STEC isolated from patients with hemolytic uremic syndrome (HUS). Thus, this study confirms that cattle are a major reservoir of STEC pathogenic for humans. To our knowledge, this is the first study that described the presence of saa gene in STEC of serotypes O20:H19, O39:H49, O74:H28, O79:H19, O116:H21, O120:H19, O141:H7, O141:H8, O174:H21, and ONT:H21. The serotypes O120:H19 and O185:H7 were not previously reported in bovine STEC.     

Prevalence of antimicrobial resistance among serotypes of Campylobacter jejuni isolates from cattle and poultry in Japan

Penner serotypes of C. jejuni in a total of 601 isolates from apparently healthy cattle, layer and broiler chickens in Japan were examined between 2001 and 2006. Predominant serotypes were B (O: 2, 19.1%), D (O: 4, 13.5%), Y (O: 37, 7.3%) and G (O: 8, 5.8%), whereas the remaining serotypes made up less than 5% of the total isolates. The frequency of ampicillin resistance in serotype G (65.6%) was significantly higher than in serotypes D (12.5%), B (11.2%), and Y (0%). Our results suggest that serotype is one factor contributing to the prevalence of ampicillin resistance in C. jejuni isolates.     

Virulence markers and serotypes of Shiga toxin-producing Escherichia coli, isolated from cattle in Rio Grande do Sul, Brazil

AIMS: To determine the prevalence of Shiga toxin-producing Escherichia coli (STEC) and serotypes and virulence markers of the STEC isolates from beef and dairy cattle in Rio Grande do Sul, Brazil. METHODS AND RESULTS: Faecal samples from beef cattle were collected at slaughterhouses. The isolates were submitted to colony hybridization assay with specific DNA probes for stx1, stx2 and eae genes, and serotyped for the identification of O and H antigens. Thirty-nine per cent of beef cattle surveyed harboured at least one STEC strain. Among the distinct serotypes identified, 10 were shared by both beef and dairy cattle. Most of the strains isolated harboured stx2. Genotypic and phenotypic profiles allowed the identification of 34 and 31 STEC strains, isolated from beef and dairy cattle, respectively. Serotypes O10:H14, O15:H21, O96:H21, O119:H4, O124:H11, O128:H21, O137:H-, O141:H19, O159:H42, O160:H2 and O177:H11, identified in this study, have not been previously reported as STEC isolated from cattle. CONCLUSIONS: Cattle are an important reservoir of STEC strains associated with human diseases in South America. SIGNIFICANCE AND IMPACT OF THE STUDY: Determining the prevalence, genotypic profile and serotypes of STEC strains isolated from cattle enables the prediction of possible risk for public health.     

Molecular serotype identification of Streptococcus agalactiae of bovine origin by multiplex PCR-based reverse line blot (mPCR/RLB) hybridization assay

We used a multiplex PCR-based reverse line blot (mPCR/RLB) hybridization assay and sequencing of a variable region of the cps cluster to identify serotypes of 140 Streptococcus agalactiae (group B Streptococcus; GBS) isolates from cattle. Only 71 (51%) isolates were typeable using antisera, but molecular serotypes (MS) were assigned to 133 (95%) and 139 (99%) isolates by partial cpsE-cpsF-cpsG sequencing and mPCR/RLB, respectively. Ninety-four isolates (67%) belonged to MS III and most belonged to a molecular serosubtype (msst) III-3, which is uncommon among GBS isolates from humans. Our results demonstrate that cps clusters of bovine GBS differ significantly from those of GBS isolates from humans.     

Animal host associated differences in Shiga toxin-producing Escherichia coli isolated from sheep and cattle on the same farm

AIMS: To investigate if cattle on the same farm as sheep are a possible risk factor for stx in sheep and to determine whether or not sheep and cattle on the same farm share the same stx pool. METHODS AND RESULTS: Faecal samples from sheep and cattle were screened for stx by polymerase chain reaction (PCR). Of these samples, 87.6 and 64.6% were stx positive in sheep and cattle, respectively. There was no difference in stx occurrence in sheep from farms with or without cattle. From stx positive samples, 118 Shiga toxin-producing Escherichia coli (STEC) isolates were recovered by a filter-hybridization method. Serotyping, PCR and pulsed-field gel electrophoresis (PFGE) showed that there was a distinct association between serotypes, stx profiles and animal species. CONCLUSIONS: Keeping animals together in pens, which enhances faecal-oral contact, is suggested as a possible explanation for the differences seen in stx occurrence. Sheep and cattle isolates are distinctly different in serotype and stx profile although isolated from the same farm, and are more related to isolates within the same serotype with the same stx profile than to isolates with different serotype from the same farm. SIGNIFICANCE AND IMPACT OF STUDY: The study supports the animal-host relationship hypothesis suggested in other studies and indicates that the STEC sheep reservoir in Norway may not pose a serious public health risk.     

Prevalence and antimicrobial susceptibility of Salmonella spp. isolates from US cattle in feedlots in 1999 and 2000

AIMS: Faecal samples from cattle in US feedlots were evaluated for the presence of Salmonella. When Salmonella isolates were recovered the antimicrobial resistance patterns were determined. METHODS AND RESULTS: Faecal samples were collected from pen floors in 73 feedlots in 12 states during the period from October 1999 to September 2000. Pens of cattle selected for sampling were those that had been in the feedlot for the shortest period of time, the longest period of time and a randomly selected pen from the remaining pens. Faecal samples were cultured for Salmonella spp. and all Salmonella isolates were categorized by serotype. The susceptibilities of all isolates were determined using a panel of 17 antimicrobials. Overall, 6.3% (654/10,417) of the samples cultured positive for Salmonella spp. and 22.2% (94/422) of pens and 50.7% (37/73) of feedlots had one or more positive samples. There was little difference in the proportion of positive samples from short-fed (6.1%, 212/3482), random (6.4%, 217/3400) and long-fed (6.4%, 224/3485) pens of cattle. One of two pens of cattle that could not be attributed to a pen type had a single positive sample (2.0%, 1/50). Samples collected during the period of April to June (6.8%, 209/3054) and July to September (11.4%, 286/2500) were more likely to be positive than those collected during October to December (4.0%, 73/1838) and January to March (2.8%, 86/3025). The most common serotypes of Salmonella were dissimilar from those that are typically seen in human illness and cattle illness. The majority of isolates (62.8%, 441/702) were sensitive to all of the antimicrobials tested. Resistance was most frequently observed to tetracycline (35.9%, 252/702) followed by streptomycin (11.1%, 78/702), ampicillin (10.4%, 73/702) and chloramphenicol (10.4%, 73/702). Multiple resistance (resistance to > or =2 antimicrobials) was observed for 11.7% (82/702) of the isolates. CONCLUSIONS: Salmonella was isolated at low frequency from faeces of feedlot cattle and the serotypes were not those commonly associated with human illness. In addition most of the Salmonella isolates were sensitive to all the antimicrobials tested. SIGNIFICANCE AND IMPACT OF THE STUDY: This study contributes to understanding the ecology of Salmonella in cattle feedlots and the prevalence of resistance among potential food-borne pathogens.     

Human and bovine group B streptococci: two distinct populations

Group B streptococci ( Streptococcus agalactiae ) from humans and animals were compared for cultural, biochemical, serological and bacteriocin sensitivity properties. Each isolate possessed the group B carbohydrate antigen, hydrolysed hippurate, and was CAMP test positive. Most human isolates were characterized as bacitracin resistant, pigment producing, haemolytic, and salicin but not lactose utilizing. In contrast bovine isolates were usually bacitracin sensitive, non-pigment producing, non-haemolytic, salicin and lactose utilizing. Isolates from other animals behaved similarly to those from humans. Whereas human isolates belonged to a variety of serotypes and were uniformly sensitive to bacteriocins, bovine isolates showed varying sensitivity to bacteriocins and most belonged to serotype II or were non-typable. We believe these results support the belief that Strep. agalactiae from humans and cattle are separate populations sharing the same group B carbohydrate antigen.     

Epidemiological relatedness and clonal types of natural populations of Escherichia coli strains producing Shiga toxins in separate populations of cattle and sheep.

Two separate animal populations consisting of a herd of cattle (19 animals) and a flock of sheep (25 animals) were investigated for strains of Escherichia coli producing Shiga toxins (STEC) over a time period of 6 months. Thirty-three STEC were isolated from 63.2% of cattle and grouped into 11 serotypes and eight electrophoretic types (ETs) by multilocus enzyme analysis. In sheep, 88% of the animals excreted STEC (n = 67 isolates) belonging to 17 different serotypes and 12 different ETs. STEC from cattle and sheep differed with respect to serotype, and only 4 of the 16 ETs occurred in both animal populations. In cattle, ET14 (O116:H21) strains predominated, whereas other STEC serotypes occurred only sporadically. The predominating STEC types in sheep were ET4 (O125 strains), ET11 (O128:H2 and others), and ET14 (O146:H21). In contrast to their diversity, STEC originating from the same animal population were similar with respect to Shiga toxin (stxy genes. Almost all STEC isolated from cattle were positive for stx2 and stx2c; only one was positive for stx1. In sheep, almost all STEC isolated were positive for stx1 and stx2, whereas stx2c was not found. XbaI-digested DNAs of genetically closely related O146:H21 strains have different restriction profiles which were associated with size alterations in XbaI fragments hybridizing with stx1- and stx2-specific DNA probes. Our results indicate that stx-encoding bacteriophages might be the origin of the genetic heterogeneity in STEC from animals.     

Phage Types of Salmonella enterica ssp. enterica serovar Typhimurium Isolated from Production Animals and Humans i Denmark

S. Typhimurium is one of the 2 most common salmonella serotypes causing human salmonellosis in Denmark. In order to illustrate the significance of different production animals as a source of infection, 1461 isolates were characterized by phage typing. The isolates originated from human patients and from cattle, pigs and poultry. By phage typing the isolates could be separated in 35 different phage types. Five types (10, 12, 66, 110 and 135) predominated and comprised 78.8% of the isolates. In humans, 57.3% of the isolates were phage type 12. This phage type was also predominant in pig herds and, to a lesser degree, in cattle. Phage types 110, 120, 135 and 193 constituted 86.5% of the poultry isolates while these phage types only made up 12.9% of the human isolates. The investigation showed that pigs are probably a major source of S. Typhimurium infection in humans in Denmark today.     

Human viruses in animals in West Bengal: An ecological analysis

Viruses normally associated with man, or antibodies to such viruses, were found in animals in two villages in West Bengal during a 6-month survey. Eleven serotypes were isolated from the feces of seven vertebrate species and one serotype from flies. In one of the villages, echovirus 7 was most frequently isolated at the start of the study and was obtained from six species, including both mammals and birds, whereas poliovirus 1 occurred in two species at the end of the study. Repeated isolations were made from two dogs over a 2- to 3-month period. The coprophagous, terrestrial species (dogs and chickens) yielded the highest number of isolates and the highest number of serotypes, whereas the primarily nonterrestrial species (monkeys and house crows) yielded the least number of isolates and serotypes. Most of the cattle and some of the goats had antibodies to a Hong Kong (H₃N₂)-like strain of influenza. The viruses occurred with a frequency that may have been proportional to the abundance of each serotype in the environment. No clinical symptoms were observed in the viral-positive animals.This research was supported by the U.S. Public Health Service through Research Grant No. 5 RO7 AI100048-13 from the National Institutes of Health to The Johns Hopkins University International Center for Medical Research.     

Characterization of the coliform and enteric bacilli in the environment of calves with colibacillosis

In the first part of the present study the coliform and enteric bacilli in the environment of calves with colibacillosis were examined. The occurrence, number, and pathogenic properties of Escherichia coli in barnyard soils were obtained from six cattle ranches. The O and K serogroups of E. coli isolates obtained from the feces of calves with colibacillosis born at these cattle ranches were determined, and their serotypes were compared with the E. coli O and K serotypes found in soils. The results showed a reservoir of potentially pathogenic E. coli in barnyard soils contaminated with bovine feces. For the second part of this study, 6 healthy calves and 51 calves with colibacillosis were studied. The numbers of total aerobic heterotrophic bacteria, total streptococci, fecal streptococci, total coliforms, and fecal coliforms in the feces of calves were determined. In addition, coliform and enteric bacilli from the feces of both healthy and diseased calves were identified, and their indole, methyl red, Voges-Proskauer, citrate (IMViC) types were described. In parallel, the IMViC types of coliform and enteric bacilli isolated from barnyard soils previously contaminated with bovine feces were compared with those isolated from uncontaminated soils. All fecal specimens were also examined for the presence of rotavirus. No significant effect on the numbers of the bacterial types was found. The results suggest that the predominant IMViC types found in the feces of calves with colibacillosis originate from the soil. From this study it is apparent that the occurrence, number, and survival of E. coli in barnyard soils is related to ranch husbandry and sanitary practices.     

Characterization of the coliform and enteric bacilli in the environment of calves with colibacillosis.

In the first part of the present study the coliform and enteric bacilli in the environment of calves with colibacillosis were examined. The occurrence, number, and pathogenic properties of Escherichia coli in barnyard soils were obtained from six cattle ranches. The O and K serogroups of E. coli isolates obtained from the feces of calves with colibacillosis born at these cattle ranches were determined, and their serotypes were compared with the E. coli O and K serotypes found in soils. The results showed a reservoir of potentially pathogenic E. coli in barnyard soils contaminated with bovine feces. For the second part of this study, 6 healthy calves and 51 calves with colibacillosis were studied. The numbers of total aerobic heterotrophic bacteria, total streptococci, fecal streptococci, total coliforms, and fecal coliforms in the feces of calves were determined. In addition, coliform and enteric bacilli from the feces of both healthy and diseased calves were identified, and their indole, methyl red, Voges-Proskauer, citrate (IMViC) types were described. In parallel, the IMViC types of coliform and enteric bacilli isolated from barnyard soils previously contaminated with bovine feces were compared with those isolated from uncontaminated soils. All fecal specimens were also examined for the presence of rotavirus. No significant effect on the numbers of the bacterial types was found. The results suggest that the predominant IMViC types found in the feces of calves with colibacillosis originate from the soil. From this study it is apparent that the occurrence, number, and survival of E. coli in barnyard soils is related to ranch husbandry and sanitary practices.     

<Emphasis Type="Italic">Salmonella</Emphasis> Isolated from Animals and Feed Production in Sweden Between 1993 and 1997

This paper presents Salmonella data from animals, feedstuffs and feed mills in Sweden between 1993 and 1997. During that period, 555 isolates were recorded from animals, representing 87 serotypes. Of those, 30 serotypes were found in animals in Sweden for the first time. The majority of all isolates from animals were S. Typhimurium (n = 91), followed by S. Dublin (n = 82). There were 115 isolates from cattle, 21 from broilers, 56 from layers and 18 from swine. The majority of these isolates were from outbreaks, although some were isolated at the surveillance at slaughterhouses. The number of isolates from the feed industry was similar to that of the previous 5-year period. Most of those findings were from dust and scrapings from feed mills, in accordance with the HACCP programme in the feed control programme. It can be concluded that the occurrence of Salmonella in animals and in the feed production in Sweden remained favourable during 1993–97.     

Antimicrobial Susceptibility Profiles of <Emphasis Type="Italic">Salmonella</Emphasis><Emphasis Type="Italic">enterica</Emphasis> Serotypes Recovered from Pens of Commercial Feedlot Cattle Using Different Types of Composite Samples

Salmonella enterica in cattle production systems may be associated with important human and animal disease issues. However, tremendous diversity exists among Salmonella recovered, and more information is needed about strains of greatest potential health concern, particularly those that are multidrug resistant (MDR). By characterizing Salmonella isolates from commercial feedlot pens, this study aimed to evaluate the strain diversity and prevalence of MDR Salmonella from different types of composite pen samples. Antimicrobial susceptibility profiles, serotype, and presence or absence of the integron-encoded intI1 gene were determined for 530 Salmonella isolates recovered using composite rope (n = 335), feces (n = 59), and water (n = 136) samples from 21 pens in 3 feedlots. The study investigated only pens with available isolates from multiple sample types. Most isolates (83.0%) of the 19 Salmonella serotypes identified were susceptible or intermediately susceptible to all the antimicrobials evaluated. Resistance to sulfisoxazole (14.9%), streptomycin (3.8%), and tetracycline (3.6%) were the most common. None of the isolates tested positive for a class 1 integron, and only 2.5% were resistant to multiple antimicrobials. All the MDR isolates, namely, serotypes Uganda (n = 9), Typhimurium (n = 2), and Give (n = 2), were resistant to at least five antimicrobials. Most MDR isolates (n = 11) were from two pens during 1 week within one feedlot. Overall, many Salmonella isolates collected within a pen were similar in terms of serotype and antimicrobial susceptibility regardless of sample type. However, MDR Salmonella and rare serotypes were not recovered frequently enough to suggest a general strategy for appropriate composite sampling of feedlot cattle populations for Salmonella detection and monitoring.     

Genetic relatedness among Campylobacter jejuni serotyped isolates of diverse origin as determined by numerical analysis of amplified fragment length polymorphism (AFLP) profiles

AIMS: To use amplified fragment length polymorphism (AFLP) analysis to evaluate the genetic relatedness among 254 Campylobacter jejuni reference and field strains of diverse origin representing all defined 'Penner' serotypes for this species. METHODS AND RESULTS: Field strains (n = 207) from human diarrhoea and diverse animal and environmental sources were collected mainly through a National surveillance programme in Denmark and serotyped by use of the established 'Penner' scheme. Genetic relationships among these isolates, and the archetypal serotype reference strains, were assessed by numerical analysis of AFLP profiles derived from genomic DNA. Extensive genetic diversity was seen among the strains examined; however, 43 groups of isolates were identified at the 92% similarity (S-) level. Thirteen groups contained isolates from a single host, possibly representing genotypes of 'low risk' to human health. The remaining 30 groups contained isolates from humans, chickens and associated food products, cattle, sheep, turkeys, ostriches and/or dogs. Strains assigned to serotypes 2, 6/7, 11 and 12 formed major clusters at the 77.6% S-level. Most other serotypes did not form homogeneous clusters. CONCLUSIONS: High-resolution genotyping applied to strains from a comprehensive range of sources provides evidence for multiple sources of sporadic C. jejuni infection. The results suggest that public health protection measures should be directed at all foods of animal origin. SIGNIFICANCE AND IMPACT OF THE STUDY: The genetic relatedness among all 'Penner' serotypes of C. jejuni is assessed by AFLP analysis. In addition, further evidence of epidemic and host-specific clones of C. jejuni is provided.     

Salmonella in surface waters of central New York state.

Six tributary streams and southern Cayuga Lake in central New York state were sampled for the presence of Salmonella on swabs immersed for 4 days. Of a total of 322 swabs, 39% yielded salmonellae. Swabs were cultured in tetrathionate enrichment at 41.5 degrees C. Isolations were made from brilliant green agar. Salmonellae were isolated from many sites on the streams and from some lake sites. Twenty-five serotypes (11 somatic antigen groups) and a distinct biotype of S. typhimurium (H2S negative) were found. Most frequent isolates, in order of decreasing occurrence, were S. typhimurium, S. thompson, S. oranienburg, and S. enteritidis. Several uncommon isolates also appeared. When tested for mouse infectivity, the isolates generally showed little or no virulence. The incidence of clinical salmonellosis among humans was low in the area and the variety of serotypes had not been noted among cattle. The presence of Salmonella in waters ranging in classification from potable to agricultural and industrial indicated the existence of a low level and undefined reservoirs of the bacteria in the region.     

Prevalence of Campylobacter spp. in cattle in Finland and antimicrobial susceptibilities of bovine Campylobacter jejuni strains

The study investigated the prevalence of Campylobacter spp. in Finnish cattle at slaughter and carcass contamination after slaughter. During the period January to December 2003, bovine rectal fecal samples (n=952) and carcass surface samples (n=948) from 12 out of 15 Finnish slaughterhouses were examined. In total, campylobacters were detected in 31.1% of fecal samples and in 3.5% of carcass surface samples. Campylobacter jejuni was isolated from 19.5%, Campylobacter coli from 2.2%, and presumptive Campylobacter hyointestinalis from 10.8% of fecal samples. Campylobacters were detected in 4.4% and 37.4% of the fecal samples examined both by direct culture and by enrichment (n=730), respectively, suggesting a low level of campylobacters in the intestinal content. A slightly increasing trend was observed in the overall prevalence of campylobacters towards the end of summer and autumn. Seventeen different serotypes were detected among the fecal C. jejuni isolates using a set of 25 commercial antisera for serotyping heat-stable antigens (Penner) of C. jejuni by passive hemagglutination. The predominant serotypes, Pen2 and Pen4-complex, were isolated from 52% of the fecal samples. Subtyping by pulsed-field gel electrophoresis (SmaI) yielded 56 and 20 subtypes out of 330 fecal and 70 carcass C. jejuni isolates, respectively. MICs of ampicillin, enrofloxacin, erythromycin, gentamicin, nalidixic acid, and oxytetracycline for 187 C. jejuni isolates were determined using a commercial broth microdilution method. Sixteen (9%) of the isolates were resistant to at least one of the antimicrobials tested. Resistance to nalidixic acid was most commonly detected (6%). No multiresistance was observed.     

Genomic sequences of Australian bluetongue virus prototype serotypes reveal global relationships and possible routes of entry into Australia

Bluetongue virus (BTV) is transmitted by biting midges (Culicoides spp.). It causes disease mainly in sheep and occasionally in cattle and other species. BTV has spread into northern Europe, causing disease in sheep and cattle. The introduction of new serotypes, changes in vector species, and climate change have contributed to these changes. Ten BTV serotypes have been isolated in Australia without apparent associated disease. Simplified methods for preferential isolation of double-stranded RNA (dsRNA) and template preparation enabled high-throughput sequencing of the 10 genome segments of all Australian BTV prototype serotypes. Phylogenetic analysis reinforced the Western and Eastern topotypes previously characterized but revealed unique features of several Australian BTVs. Many of the Australian BTV genome segments (Seg-) were closely related, clustering together within the Eastern topotypes. A novel Australian topotype for Seg-5 (NS1) was identified, with taxa spread across several serotypes and over time. Seg-1, -2, -3, -4, -6, -7, -9, and -10 of BTV_2_AUS_2008 were most closely related to the cognate segments of viruses from Taiwan and Asia and not other Australian viruses, supporting the conclusion that BTV_2 entered Australia recently. The Australian BTV_15_AUS_1982 prototype was revealed to be unusual among the Australian BTV isolates, with Seg-3 and -8 distantly related to other BTV sequences from all serotypes.