Extended-spectrum beta-lactamase-producing Escherichia coli harbouring sul and mcr-1 genes isolates from fish gut contents in the Mekong Delta,Vietnam

This study investigated the existence of sulfonamides and colistin resistance genes among extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli recovered from fish gut in Vietnam and evaluated the susceptibility patterns of the ESBL-producing E. coli to relevant antimicrobials. A total of 88 ESBL-producing E. coli isolates were analysed for the presence of the ESBLs, sul (1, 2, 3) and mcr (1–3) genes by PCR. Antimicrobial resistance phenotypes of isolates were determined by disc diffusion. Results showed that: (i) A high prevalence of 94·3% of sulfonamide resistance was observed in 88 isolates. Moreover, the existence of 2·3% of ESBL-producing E. coli harbouring mcr-1 gene were detected; (ii) The phylogenetic types A and B1 were most frequent, and the bla_CTX-M group1 and bla_TEM genes encoding ESBL were detected in 47·7% of the isolates; (iii) ESBL-producing E. coli harbouring mcr-1 gene exhibited resistance to 11 antibiotics. The existence of mcr-1 and sul1,2,3 genes and the extremely high level of multiple drug resistance in all ESBL-producing E. coli isolates obtained from sampled fish in Vietnam is a major concern. Therefore, it is imperative to monitor ESBL-producing E. coli in the river waters of Vietnam.     

Effects of Colistin and Bacteriocins Combinations on the In Vitro Growth of <Emphasis Type="Italic">Escherichia coli</Emphasis> Strains from Swine Origin

Escherichia coli strains from swine origin, either susceptible or resistant to colistin, were grown under planktonic and biofilm cultures. After which, they were treated with antibacterial agents including nisin and enterocin DD14 bacteriocins, colistin and their combinations. Importantly, the combination of colistin, enterocin DD14 and nisin eradicated the planktonic and biofilm cultures of E. coli CIP54127 and the E. coli strains with colistin-resistance phenotype such as E. coli 184 (mcr-1 ⁺) and E. coli 289 (mcr-1 ^?), suggesting therefore that bacteriocins from lactic acid bacteria could be used as agents with antibiotic augmentation capability.     

Development of SCAR primers based on a repetitive DNA fingerprint for Escherichia coli detection

The present study aimed to use enterobacterial repetitive intergenic consensus (ERIC) fingerprints to design SCAR primers for the detection of Escherichia coli. The E. coli strains were isolated from various water sources. The primary presumptive identification of E. coli was achieved using MacConkey agar. Nineteen isolates were selected and confirmed to be E. coli strains based on seven biochemical characteristics. ERIC-PCR with ERIC 1R and ERIC 2 primers were used to generate DNA fingerprints. ERIC-PCR DNA profiles showed variant DNA profiles among the tested E. coli strains and distinguished all E. coli strains from the other tested bacterial strains. A 350 bp band that predominated in five E. coli strains was used for the development of the species-specific SCAR primers EC-F1 and EC-R1. The primers showed good specificity for E. coli, with the exception of a single false positive reaction with Sh. flexneri DMST 4423. The primers were able to detect 50 pg and 10⁰ CFU/ml of genomic DNA and cells of E. coli, respectively.     

Prevalence of Escherichia coli strains resistance to antibiotics in wound infections and raw milk

Antibiotic-resistant Escherichia coli strains including extended-spectrum β-lactamase (ESBL) isolates are globally widespread in medical, food, and environmental sources. Some of these strains are considered the most pathogenic bacteria in humans. The present work examined the predominance of antibiotic resistance in E. coli strains in wound infections comparing with E. coli strains isolated from a raw milk as a potential source of those strains. The wound infections included abdomen, anus, arm, back, buttock, chest, foot, hand, head, leg, lung, mouth, neck, penis, thigh, toe, and vagina infections. In total, 161 and 153 isolates identified as E. coli were obtained from wound infections and raw milk, respectively. A Vitek 2 system innovated by bioMérieux, France was applied to perform the identification and susceptibility tests. The E. coli isolates that have ability to produce ESBL were detected by an ESBL panel and NO45 card (bioMérieux). Over half of the E. coli were from abdomen, back, and buttock wound infections. More than 50%of the E. coli isolates obtained from wound infections were resistant to cefazolin, ampicillin, cefuroxime, ciprofloxacin, mezlocillin, moxifloxacin, piperacillin, and tetracycline; 70% of the isolates from wound infections and 0% of the isolates from raw milk were E. coli isolates produced ESBL. The data showed that the strains resistance to multi-antibiotic and produced ESBL are more widespread among wound infections than in raw milk.     

Relationship between Phylogenetic Groups, Genotypic Clusters, and Virulence Gene Profiles of Escherichia coli Strains from Diverse Human and Animal Sources

Escherichia coli strains in water may originate from various sources, including humans, farm and wild animals, waterfowl, and pets. However, potential human health hazards associated with E. coli strains present in various animal hosts are not well known. In this study, E. coli strains from diverse human and animal sources in Minnesota and western Wisconsin were analyzed for the presence of genes coding for virulence factors by using multiplex PCR and biochemical reactions. Of the 1,531 isolates examined, 31 (2%) were found to be Shiga toxin-producing E. coli (STEC) strains. The majority of these strains, which were initially isolated from the ruminants sheep, goats, and deer, carried the stx_1c and/or stx_2d, ehxA, and saa genes and belonged to E. coli phylogenetic group B1, indicating that they most likely do not cause severe human diseases. All the STEC strains, however, lacked eae. In contrast, 26 (1.7%) of the E. coli isolates examined were found to be potential enteropathogenic E. coli (EPEC) strains and consisted of several intimin subtypes that were distributed among various human and animal hosts. The EPEC strains belonged to all four phylogenetic groups examined, suggesting that EPEC strains were relatively widespread in terms of host animals and genetic background. Atypical EPEC strains, which carried an EPEC adherence factor plasmid, were identified among E. coli strains from humans and deer. DNA fingerprint analyses, done using the horizontal, fluorophore-enhanced repetitive-element, palindromic PCR technique, indicated that the STEC, potential EPEC, and non-STEC ehxA-positive E. coli strains were genotypically distinct and clustered independently. However, some of the potential EPEC isolates were genotypically indistinguishable from nonpathogenic E. coli strains. Our results revealed that potential human health hazards associated with pathogenic E. coli strains varied among the animal hosts that we examined and that some animal species may harbor a greater number of potential pathogenic strains than other animal species.     

Detection of Cytolethal Distending Toxin Activity and cdt Genes in Campylobacter spp. Isolated from Chicken Carcasses

This study was designed to determine whether isolates from chicken carcasses, the primary source of Campylobacter jejuni and Campylobacter coli in human infections, commonly carry the cdt genes and also whether active cytolethal distending toxin (CDT) is produced by these isolates. Campylobacter spp. were isolated from all 91 fresh chicken carcasses purchased from local supermarkets. Campylobacter spp. were identified on the basis of both biochemical and PCR tests. Of the 105 isolates, 70 (67%) were identified as C. jejuni, and 35 (33%) were identified as C. coli. PCR tests amplified portions of the cdt genes from all 105 isolates. Restriction analysis of PCR products indicated that there appeared to be species-specific differences between the C. jejuni and C. coli cdt genes, but that the restriction patterns of the cdt genes within strains of the same species were almost invariant. Quantitation of active CDT levels produced by the isolates indicated that all C. jejuni strains except four (94%) had mean CDT titers greater than 100. Only one C. jejuni strain appeared to produce no active CDT. C. coli isolates produced little or no toxin. These results confirm the high rate of Campylobacter sp. contamination of fresh chicken carcasses and indicate that cdt genes may be universally present in C. jejuni and C. coli isolates from chicken carcasses.     

Enterotoxigenic Bacteria in Food and Water from an Ethiopian Community

Food and water samples from an Ethiopian community were screened for the presence of enterotoxin-producing bacteria. Using the Chinese hamster ovary cell assay, 40 of 213 isolates (18.8%) produced heat-labile (LT) enterotoxin. These LT-producing isolates comprised 33 of 177 (18.6%) strains from 24 of 68 food samples (35.3%) and 7 of 36 (19.4%) isolates of 4 of 17 water samples (23.5%). One LT-producing strain each of Salmonella emek and of Shigella dysenteriae was found. Three pseudomonads, all LT producers, produced heat-stable enterotoxin as gauged by the suckling mouse test. Two strains of LT-enterotoxigenic Escherichia coli O68 were found in water samples. No enterotoxigenic E. coli were isolated from food samples, but 13 of the LT-producing strains were Enterobacter, Klebsiella, Serratia, and Proteus species, and 7 food samples yielded more than one species of enterotoxigenic bacterium. Of the enterotoxigenic isolates from food, 15 were oxidase-positive strains of the genera Aeromonas, Pseudomonas, Achromobacter, Flavobacterium, and Vibrio. LT-enterotoxigenic Enterobacter, Acinetobacter, Klebsiella, Proteus, Providencia, and Serratia species represented 20 of the food and water isolates. Culture supernatant fluids of representative strains of oxidase-positive and oxidase-negative species giving positive reactions in Chinese hamster ovary cell tests induced fluid accumulation in rabbit ileal loops. Eight of the food samples and two of the water samples contained more than one isolate or species of enterotoxigenic bacterium. The stability of the LT production by oxidase-positive bacteria and non-E. coli strains was assessed by the rabbit skin and adrenal cell tests after 9 months and 1 year of storage, respectively, in Trypticase soy broth with glycerol at −70°C. Only 33% of the oxidase-positive strains were still LT enterotoxigenic. Of the oxidase-negative strains, 50 and 33% were LT producing at 9 months and 1 year, respectively. None of the E. coli isolates, both enterotoxigenic and nonenterotoxigenic, possessed K88, K99, or colonization factor antigen. The survey demonstrates the presence in food and water of enterotoxigenic bacteria of the same species as those isolated from cases of infantile diarrhea in the same community, although a correlation between these sources and infantile diarrhea remains to be established.     

Beta-Lactamase Producing Escherichia coli Isolates in Imported and Locally Produced Chicken Meat from Ghana

The use of antibiotics in food animals is of public health concern, because resistant zoonotic pathogens can be transmitted to humans. Furthermore, global trade with food may rapidly spread multi-resistant pathogens between countries and even continents. The purpose of the study was to investigate whether imported chicken meat and meat from locally reared chicken are potential sources for human exposure to multi resistant Escherichia coli isolates. 188 samples from imported and locally produced chicken meat were sampled and analyzed. 153 bacteria isolates were successfully cultured and identified as E. coli using MALDI-ToF. Of these 109 isolates were from meat whereas the remaining 44 were isolated from the cloaca of locally reared live chickens. Antimicrobial susceptibility test was done on the identified E. coli isolates. Additionally, beta-lactamases production (ESBL and/or AmpC) were phenotypically confirmed on all isolates showing resistance to cefpodoxime. Beta-lactamase producing (BLP) E. coli meat isolates were further genotyped. Antimicrobial resistance to four antibiotic markers with highest resistance was detected more frequently in isolates from local chickens compared to imported chickens (tetracycline 88.9% vs. 57.5%, sulphonamide 75.0% vs. 46.6%, ampicillin 69.4% vs. 61.6% and trimethoprim 66.7% vs. 38.4%). Beta-lactamase production was found in 29 E. coli meat isolates, with 56.9% of them being multiple drug resistant (≥ 3). The predominant phylogroup identified was B1 followed by A and D, with similar distribution among the isolates from meat of locally reared chickens and imported chickens. Beta-lactamase producing genotype bla _CTX-M-15 (50%; 10/20) was the most frequently drug resistant gene detected. More BLP E. coli isolates were found in imported chicken meat compared to locally reared chickens, demonstrating that these isolates may be spreading through food trade. In conclusion, both imported and locally produced chicken meats are potential sources for human exposure to BLP E. coli.     

Clonal Populations of Thermotolerant Enterobacteriaceae in Recreational Water and Their Potential Interference with Fecal Escherichia coli Counts

Bacterial strains were isolated from beach water samples using the original Environmental Protection Agency method for Escherichia coli enumeration and analyzed by pulsed-field gel electrophoresis (PFGE). Identical PFGE patterns were found for numerous isolates from 4 of the 9 days sampled, suggesting environmental replication. 16S rRNA gene sequencing, API 20E biochemical testing, and the absence of β-glucuronidase activity revealed that these clonal isolates were Klebsiella, Citrobacter, and Enterobacter spp. In contrast, 82% of the nonclonal isolates from water samples were confirmed to be E. coli, and 16% were identified as other fecal coliforms. These nonclonal isolates produced a diverse range of PFGE patterns similar to those of isolates obtained directly from untreated sewage and gull droppings. β-Glucuronidase activity was critical in distinguishing E. coli from other fecal coliforms, particularly for the clonal isolates. These findings demonstrate that E. coli is a better indicator of fecal pollution than fecal coliforms, which may replicate in the environment and falsely elevate indicator organism levels.     

Genomic Comparative Study of Bovine Mastitis Escherichia coli

Escherichia coli, one of the main causative agents of bovine mastitis, is responsible for significant losses on dairy farms. In order to better understand the pathogenicity of E. coli mastitis, an accurate characterization of E. coli strains isolated from mastitis cases is required. By using phylogenetic analyses and whole genome comparison of 5 currently available mastitis E. coli genome sequences, we searched for genotypic traits specific for mastitis isolates. Our data confirm that there is a bias in the distribution of mastitis isolates in the different phylogenetic groups of the E. coli species, with the majority of strains belonging to phylogenetic groups A and B1. An interesting feature is that clustering of strains based on their accessory genome is very similar to that obtained using the core genome. This finding illustrates the fact that phenotypic properties of strains from different phylogroups are likely to be different. As a consequence, it is possible that different strategies could be used by mastitis isolates of different phylogroups to trigger mastitis. Our results indicate that mastitis E. coli isolates analyzed in this study carry very few of the virulence genes described in other pathogenic E. coli strains. A more detailed analysis of the presence/absence of genes involved in LPS synthesis, iron acquisition and type 6 secretion systems did not uncover specific properties of mastitis isolates. Altogether, these results indicate that mastitis E. coli isolates are rather characterized by a lack of bona fide currently described virulence genes.     

Differences in Virulence among Escherichia coli O157:H7 Strains Isolated from Humans during Disease Outbreaks and from Healthy Cattle

Escherichia coli O157:H7 causes life-threatening outbreaks of diarrhea, hemorrhagic colitis, and hemolytic-uremic syndrome in humans and significant economic loss in agriculture and could be a potential agent of bioterrorism. Although the prevalence of E. coli O157:H7 in cattle and other species with which humans have frequent contact is high, human infections are relatively uncommon, despite a low infectious dose. A plausible explanation for the low disease incidence is the possibility that not all strains are virulent in humans. If there are substantial differences in virulence among strains in nature, then human disease may select for high virulence. We used a gnotobiotic piglet model to investigate the virulence of isolates from healthy cattle and from humans in disease outbreaks and to determine the correlation between production of Shiga toxin 1 (Stx1) and Stx2 and virulence. Overall, E. coli O157:H7 strains isolated from healthy cattle were less virulent in gnotobiotic piglets than strains isolated from humans during disease outbreaks. The amount of Stx2 produced by E. coli O157:H7 strains correlated with strain virulence as measured by a reduction in piglet survival and signs of central nervous system disease due to brain infarction. The amount of Stx1 produced in culture was not correlated with the length of time of piglet survival or with signs of central nervous system disease. We suggest that disease outbreaks select for producers of high levels of Stx2 among E. coli O157:H7 strains shed by animals and further suggest that Stx1 expression is unlikely to be significant in human outbreaks.     

Houseflies (Musca domestica) as Vectors for Extended-Spectrum β-Lactamase-Producing Escherichia coli on Spanish Broiler Farms

Flies may act as potential vectors for the spread of resistant bacteria to different environments. This study was intended to evaluate the presence of Escherichia coli strains resistant to cephalosporins in flies captured in the areas surrounding five broiler farms. Phenotypic and molecular characterization of the resistant population was performed by different methods: MIC determination, pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and phylotyping. The presence of extended-spectrum beta-lactamase (ESBL) genes, their plasmid location, and the mobile genetic elements involved in their mobilization were studied. Additionally, the presence of 35 genes associated with virulence was evaluated. Out of 682 flies captured, 42 yielded ESBL-producing E. coli. Of these isolates, 23 contained bla_CTX-M-1, 18 contained bla_CTX-M-14, and 1 contained bla_CTX-M-9. ESBL genes were associated mainly with the presence of the IncI1 and IncFIB replicons. Additionally, all the strains were multiresistant, and five of them also harbored qnrS. Identical PFGE profiles were found for E. coli isolates obtained from flies at different sampling times, indicating a persistence of the same clones in the farm environment over months. According to their virulence genes, 81% of the isolates were considered avian-pathogenic E. coli (APEC) and 29% were considered extraintestinal pathogenic E. coli (ExPEC). The entrance of flies into broiler houses constitutes a considerable risk for colonization of broilers with multidrug-resistant E. coli. ESBLs in flies reflect the contamination status of the farm environment. Additionally, this study demonstrates the potential contribution of flies to the dissemination of virulence and resistance genes into different ecological niches.     

Phenotypic and Genotypic Characterization of Avian Escherichia coli O86:K61 Isolates Possessing a Gamma-Like Intimin

Escherichia coli O86:K61 has long been associated with outbreaks of infantile diarrhea in humans and with diarrheal disease in many animal species. Studies in the late 1990s identified E. coli O86:K61 as the cause of mortality in a variety of wild birds, and in this study, 34 E. coli O86:K61 isolates were examined. All of the isolates were nonmotile, but most elaborated at least two morphologically distinct surface appendages that were confirmed to be type 1 and curli fimbriae. Thirty-three isolates were positive for the eaeA gene encoding a gamma type of intimin. No phenotypic or genotypic evidence was obtained for elaboration of Shiga-like toxins, but most isolates possessed the gene coding for the cytolethal distending toxin. Five isolates were selected for adherence assays performed with tissue explants and HEp-2 cells, and four of these strains produced attaching and effacing lesions on HEp-2 cells and invaded the cells, as determined by transmission electron microscopy. Two of the five isolates were inoculated orally into 1-day-old specific-pathogen-free chicks, and both of these isolates colonized, invaded, and persisted well in this model. Neither isolate produced attaching and effacing lesions in chicks, although some pathology was evident in the alimentary tract. No deaths were recorded in inoculated chicks. These findings are discussed in light of the possibility that wild birds are potential zoonotic reservoirs of attaching and effacing E. coli.     

An Investigation of the Diversity of Strains of Enteroaggregative Escherichia coli Isolated from Cases Associated with a Large Multi-Pathogen Foodborne Outbreak in the UK

Following a large outbreak of foodborne gastrointestinal (GI) disease, a multiplex PCR approach was used retrospectively to investigate faecal specimens from 88 of the 413 reported cases. Gene targets from a range of bacterial GI pathogens were detected, including Salmonella species, Shigella species and Shiga toxin-producing Escherichia coli, with the majority (75%) of faecal specimens being PCR positive for aggR associated with the Enteroaggregative E. coli (EAEC) group. The 20 isolates of EAEC recovered from the outbreak specimens exhibited a range of serotypes, the most frequent being O104:H4 and O131:H27. None of the EAEC isolates had the Shiga toxin (stx) genes. Multilocus sequence typing and single nucleotide polymorphism analysis of the core genome confirmed the diverse phylogeny of the strains. The analysis also revealed a close phylogenetic relationship between the EAEC O104:H4 strains in this outbreak and the strain of E. coli O104:H4 associated with a large outbreak of haemolytic ureamic syndrome in Germany in 2011. Further analysis of the EAEC plasmids, encoding the key enteroaggregative virulence genes, showed diversity with respect to FIB/FII type, gene content and genomic architecture. Known EAEC virulence genes, such as aggR, aat and aap, were present in all but one of the strains. A variety of fimbrial genes were observed, including genes encoding all five known fimbrial types, AAF/1 to AAF/V. The AAI operon was present in its entirety in 15 of the EAEC strains, absent in three and present, but incomplete, in two isolates. EAEC is known to be a diverse pathotype and this study demonstrates that a high level of diversity in strains recovered from cases associated with a single outbreak. Although the EAEC in this study did not carry the stx genes, this outbreak provides further evidence of the pathogenic potential of the EAEC O104:H4 serotype.     

Isolation and identification of new lactobacilli from goatling stomach and investigation of reuterin production in Lactobacillus reuteri strains

Five new strains of lactobacilli isolated from goatling??s stomach were identified by molecular?Cbiological approaches. Profiles of fermentable saccharides, Gram staining, and cell morphology were also determined. They were identified as Lactobacillus reuteri (strains KO4b, KO4m, KO5) and as Lactobacillus plantarum (strains KG1z, KG4). In DNA samples of all newly isolated L. reuteri strains as well as in L. reuteri E (Lreu E; originated from lamb), the part of gldC gene, coding large subunit of glycerol dehydratase, that is necessary for 3-hydroxypropionaldehyde (3-HPA; reuterin) production, was amplified using two designed primer sets. However, the 3-HPA production was revealed only in the strain Lreu E. It produced five- or ten-fold lower amount of 3-HPA in comparison with probiotic L. reuteri ATCC 55730 in aerobic or anaerobic conditions, respectively. Moreover, Lreu E completely lost its production ability after ca. five passages in MRS medium. The co-incubation of Lreu E, but not other L. reuteri isolates, with Escherichia coli re-induced 3-HPA production. In the case of L. reuteri ATCC 55730, the 3-HPA production increased more than four times after co-incubation with E. coli.     

Molecular and Phenotypic Characterization of Escherichia coli O26:H8 among Diarrheagenic E. coli O26 Strains Isolated in Brazil

Escherichia coli strains of serogroup O26 comprise two distinct groups of pathogens, characterized as enteropathogenic E. coli (EPEC) and enterohemorrhagic E. coli (EHEC). Among the several genes related to type III secretion system-secreted effector proteins, espK was found to be highly specific for EHEC O26:H11 and its stx-negative derivative strains isolated in European countries. E. coli O26 strains isolated in Brazil from infant diarrhea, foods, and the environment have consistently been shown to lack stx genes and are thus considered atypical EPEC. However, no further information related to their genetic background is known. Therefore, in this study, we aimed to discriminate and characterize these Brazilian O26 stx-negative strains by phenotypic, genetic, and biochemical approaches. Among 44 isolates confirmed to be O26 isolates, most displayed flagellar antigen H11 or H32. Out of the 13 nonmotile isolates, 2 tested positive for fliC_H11, and 11 were fliC_H8 positive. The identification of genetic markers showed that several O26:H11 and all O26:H8 strains tested positive for espK and could therefore be discriminated as EHEC derivatives. The presence of H8 among EHEC O26 and its stx-negative derivative isolates is described for the first time. The interaction of three isolates with polarized Caco-2 cells and with intestinal biopsy specimen fragments ex vivo confirmed the ability of the O26 strains analyzed to cause attaching-and-effacing (A/E) lesions. The O26:H32 strains, isolated mostly from meat, were considered nonvirulent. Knowledge of the virulence content of stx-negative O26 isolates within the same serotype helped to avoid misclassification of isolates, which certainly has important implications for public health surveillance.     

Characterization of Shiga Toxin Gene (stx)-Positive and Intimin Gene (eae)-Positive Escherichia coli Isolates from Wastewater of Slaughterhouses in France

Wastewater samples from 12 slaughterhouses located in different regions in France were tested for the presence of stx-positive and eae-positive Escherichia coli isolates, and characteristics of the isolates obtained were determined. A total of 224 wastewater samples were collected in wastewater treatment plants at different stages of wastewater processing. Altogether, 5,001 E. coli isolates were obtained by colony counting and screened for the presence of stx and eae genes by multiplex PCR. stx-positive and eae-positive E. coli isolates were detected in 25% of the samples collected; they were found in 13% and 3% of the samples obtained from treated effluent and sludge, respectively, suggesting that they could be spread into the environment. Screening of the samples collected by immunomagnetic separation allowed us to isolate 31 additional E. coli serogroup O157 isolates. Four of these isolates harbored stx and eae genes. All stx-positive and eae-positive E. coli isolates were analyzed for eae and stx genetic variants, as well as for additional virulence factors and serotypes. Our results suggest that the majority of the stx- and eae-positive E. coli isolates from wastewater have low virulence for humans. However, the diversity of the enterohemorrhagic E. coli-associated virulence factors in the strains indicates that the environment may play an important role in the emergence of new pathogenic enterohemorrhagic E. coli strains.     

Genotype Analysis of Escherichia coli Strains Isolated from Children and Chickens Living in Close Contact

Escherichia coli isolates from rectal swabs from 62 chickens and stools from 42 children living in close contact with chickens on the same farms in Kiambu district, Kenya, were compared for their genetic relatedness. Antibiotic susceptibility profiles broadly categorized isolates from the children and from the chickens into two separate clusters: the majority (144; 85.5%) of the E. coli isolates from children were multidrug resistant, while the majority (216; 87.1%) of the E. coli isolates from chickens were either fully susceptible or resistant only to tetracycline. Sixty- and 100- to 110-MDA plasmids were found to encode the transferable resistance to co-trimoxazole and tetracycline. HindIII restriction endonuclease digestion of the 60- and 100- to 110-MDA plasmids produced four distinct patterns for isolates from children and three distinct patterns for isolates from chickens. XbaI digestion of genomic DNA followed by pulsed-field gel electrophoresis (PFGE) analysis produced 14 distinct clusters. There were six distinct PFGE clusters among the isolates from children, while among the isolates from chickens there were seven distinct clusters. Only one PFGE cluster contained isolates from both children and chickens, with the isolates displaying an approximately 60% coefficient of similarity. This study showed that although several different genotypes of E. coli were isolated from children and chickens from the same farms, the E. coli strains from these two sources were distinct.     

Genetic Characterization of Escherichia coli Populations from Host Sources of Fecal Pollution by Using DNA Fingerprinting

Escherichia coli isolates were obtained from common host sources of fecal pollution and characterized by using repetitive extragenic palindromic (REP) PCR fingerprinting. The genetic relationship of strains within each host group was assessed as was the relationship of strains among different host groups. Multiple isolates from a single host animal (gull, human, or dog) were found to be identical; however, in some of the animals, additional strains occurred at a lower frequency. REP PCR fingerprint patterns of isolates from sewage (n = 180), gulls (n = 133), and dairy cattle (n = 121) were diverse; within a host group, pairwise comparison similarity indices ranged from 98% to as low as 15%. A composite dendrogram of E. coli fingerprint patterns did not cluster the isolates into distinct host groups but rather produced numerous subclusters (approximately >80% similarity scores calculated with the cosine coefficient) that were nearly exclusive for a host group. Approximately 65% of the isolates analyzed were arranged into host-specific groups. Comparable results were obtained by using enterobacterial repetitive intergenic consensus PCR and pulsed-field gel electrophoresis (PFGE), where PFGE gave a higher differentiation of closely related strains than both PCR techniques. These results demonstrate that environmental studies with genetic comparisons to detect sources of E. coli contamination will require extensive isolation of strains to encompass E. coli strain diversity found in host sources of contamination. These findings will assist in the development of approaches to determine sources of fecal pollution, an effort important for protecting water resources and public health.     

ThermotolerantCampylobacter with no or weak catalase activity isolated from dogs

ThermotolerantCampylobacter strains isolated from dog feces were characterized by phenotypical tests, DNA base composition, and DNA-DNA-hybridization. Out of 98 strains, 63 were catalase negative or weakly reacting (CNW); they were found in diarrheic as well as in healthy dogs. The CNW strains were all nalidixic-acid sensitive, hippurate negative, and grew at 42°C but not at 25°C. Seven strains were further investigated. They were sensitive to 2,3,5-triphenyl-tetrazolium chloride, reduced nitrate, and produced H₂S in the lead acetate test but not in triple-sugar-iron agar. The mol% G+C for five CNW isolates ranged from 35.2–35.8, which is higher than reported for any thermotolerantCampylobacter species. The strains also formed a well-delimitated DNA homology group with 80% or more intragroup relatedness and about 40% related toC. coli andC. jejuni.