Sharing of virulent Escherichia coli clones among household members of a woman with acute cystitis

The genetic relationship between human and pet isolates: a core genome multilocus sequence analysis of multidrug-resistant bacteria

INTRODUCTION

The global increase of multidrug-resistant organisms (MDROs) is one of the most urgent public health threats affecting both humans and animals. The One Health concept emphasizes the interconnectedness of human, animal and environmental health and highlights the need for integrated approaches to combat antimicrobial resistance (AMR). Although the sharing of environments and antimicrobial agents between companion animals and humans poses a risk for MDRO transmission, companion animals have been studied to a lesser extent than livestock animals. This study therefore used core genome multilocus sequence typing (cgMLST) to investigate the genetic relationships and putative transmission of MDROs between humans and pets.

METHODS

This descriptive integrated typing study included 252 human isolates, 53 dog isolates and 10 cat isolates collected from 2019 to 2022 at the Charité University Hospital in Berlin, Germany. CgMLST was performed to characterize methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci and multidrug-resistant gram-negative bacteria. The genetic diversity of the MDROs of the different host populations was determined and compared based on sequence type and core genome complex type.

RESULTS

Within this study the majority of samples from pets and humans was genetically distinct. However, for some isolates, the number of allelic differences identified by cgMLST was low. Two cases of putative household transmission or shared source of VR E. faecium and MDR E. coli between humans and pets were documented.

CONCLUSIONS

The interaction between humans and their pets appears to play a minor role in the spread of the MDROs studied. However, further research is needed. This study emphasizes the importance of comprehensive molecular surveillance and a multidisciplinary One Health approach to understand and contain the spread of MDROs in human and animal populations.

TRIAL REGISTRATION

The study is registered with the German Clinical Trials Register (DRKS00030009).

Transmission dynamics of ESBL/AmpC and carbapenemase-producing Enterobacterales between companion animals and humans

Antimicrobial resistance mediated by extended-spectrum beta-lactamase (ESBL)- and plasmid-mediated cephalosporinase (AmpC)-producing Enterobacterales, as well as carbapenemase-producing Enterobacterales have globally increased among companion animals, posing a potential health risk to humans in contact with them. This prospective longitudinal study investigates the transfer of ESBL/AmpC- and carbapenemase-producing Enterobacterales between companion animals and their cohabitant humans in Portugal (PT) and the United Kingdom (UK) during animal infection. Fecal samples and nasal swabs collected from dogs and cats with urinary tract infection (UTI) or skin and soft tissue infection (SSTI), and their cohabitant humans were screened for resistant strains. Relatedness between animal and human strains was established by whole-genome sequencing (WGS). ESBL/AmpC-producing Enterobacterales were detected in companion animals (PT = 55.8%; UK = 36.4%) and humans (PT = 35.9%; UK = 12.5%). Carbapenemase-producing Enterobacterales carriage was observed in one dog from Portugal (2.6%) and another dog from the UK (4.5%). Transmission of index clinical ESBL-producing Escherichia coli and Klebsiella pneumoniae strains to cohabitant humans was observed in three Portuguese households (6.9%, n = 43), with repeated isolation of the index strains on fecal samples from the animals and their cohabiting humans. In addition, longitudinal sharing of E. coli strains carried by companion animals and their owners was observed in other two Portuguese households and two households from the UK. Furthermore, a multidrug-resistant ACT-24-producing Enterobacter hormaechei subsp. hoffmannii strains were also shared within another Portuguese household. These results highlight the importance of the household as an epidemiological unit in the efforts to mitigate the spread of antimicrobial resistance, further emphasizing the need for antimicrobial surveillance in this context, capable of producing data that can inform and evaluate public health actions.

Characteristics of MDR E. coli strains isolated from Pet Dogs with clinic diarrhea: A pool of antibiotic resistance genes and virulence-associated genes

The increasing number of multi-drug resistant (MDR) bacteria in companion animals poses a threat to both pet treatment and public health. To investigate the characteristics of MDR Escherichia coli (E. coli) from dogs, we detected the antimicrobial resistance (AMR) of 135 E. coli isolates from diarrheal pet dogs by disc diffusion method (K-B method), and screened antibiotic resistance genes (ARGs), virulence-associated genes (VAGs), and population structure (phylogenetic groups and MLST) by polymerase chain reaction (PCR) for 74 MDR strains, then further analyzed the association between AMRs and ARGs or VAGs. Our results showed that 135 isolates exhibited high resistance to AMP (71.11%, 96/135), TET (62.22%, 84/135), and SXT (59.26%, 80/135). Additionally, 54.81% (74/135) of the isolates were identified as MDR E. coli. In 74 MDR strains, a total of 12 ARGs in 6 categories and 14 VAGs in 4 categories were observed, of which tetA (95.95%, 71/74) and fimC (100%, 74/74) were the most prevalent. Further analysis of associations between ARGs and AMRs or VAGs in MDR strains revealed 23 significant positive associated pairs were observed between ARGs and AMRs, while only 5 associated pairs were observed between ARGs and VAGs (3 positive associated pairs and 2 negative associated pairs). Results of population structure analysis showed that B2 and D groups were the prevalent phylogroups (90.54%, 67/74), and 74 MDR strains belonged to 42 STs (6 clonal complexes and 23 singletons), of which ST10 was the dominant lineage. Our findings indicated that MDR E. coli from pet dogs carry a high diversity of ARGs and VAGs, and were mostly belong to B2/D groups and ST10. Measures should be taken to prevent the transmission of MDR E. coli between companion animals and humans, as the fecal shedding of MDR E. coli from pet dogs may pose a threat to humans.

Longitudinal examination of urine pH, specific gravity, protein, culture, and antimicrobial resistance profiles in healthy dogs

BACKGROUND

Urine is routinely evaluated in dogs to assess health. Reference ranges for many urine properties are well established, but the scope of variation in these properties over time within healthy dogs is not well characterized.

OBJECTIVES

Longitudinally characterize urine properties in healthy dogs over 3 months.

ANIMALS

Fourteen healthy client-owned dogs.

METHODS

In this prospective study, dogs were evaluated for health; then, mid-stream free-catch urine was collected from each dog at 12 timepoints over 3 months. Urine pH, urine specific gravity (USG), protein, cultures, and antimicrobial resistance profiles were assessed at each timepoint.

RESULTS

Urine pH varied within and between dogs over time (Friedman's test: within P = .03; between P < .005). However, USG, protein, and bacterial diversity of urine were consistent within dogs over time, and only varied between dogs (Kruskal-Wallis: between all P < .005). Antimicrobial resistant isolates were identified in 12 out of 14 dogs with 34 of 48 of the isolates demonstrating resistance to amoxicillin.

CONCLUSIONS AND CLINICAL IMPORTANCE

Urine pH should be assessed at multiple timepoints via pH meter before making clinical decisions. Mid-stream free-catch urine with high concentrations of bacteria (>105  CFU/mL) should not be considered the only indicator of urinary tract infection. Bacterial isolates from dogs in this study had widespread resistance to amoxicillin/oxacillin underscoring the need for antimicrobial stewardship.

Dogs Can Be Reservoirs of Escherichia coli Strains Causing Urinary Tract Infection in Human Household Contacts

This study aimed to investigate the role played by pets as reservoirs of Escherichia coli strains causing human urinary tract infections (UTIs) in household contacts. Among 119 patients with community-acquired E. coli UTIs, we recruited 19 patients who lived with a dog or a cat. Fecal swabs from the household pet(s) were screened by antimicrobial selective culture to detect E. coli displaying the resistance profile of the human strain causing UTI. Two dogs shed E. coli isolates indistinguishable from the UTI strain by pulsed-field gel electrophoresis. Ten months later, new feces from these dogs and their owners were screened selectively and quantitatively for the presence of the UTI strain, followed by core-genome phylogenetic analysis of all isolates. In one pair, the resistance phenotype of the UTI strain occurred more frequently in human (108 CFU/g) than in canine feces (104 CFU/g), and human fecal isolates were more similar (2-7 SNPs) to the UTI strain than canine isolates (83-86 SNPs). In the other pair, isolates genetically related to the UTI strain (23-40 SNPs) were only detected in canine feces (105 CFU/g). These results show that dogs can be long-term carriers of E. coli strains causing UTIs in human household contacts.

Development of two microbial source tracking markers for detection of wastewater-associated Escherichia coli isolates

Escherichia coli has been used as an indicator of fecal pollution in environmental waters. However, its presence in environmental waters does not provide information on the source of water pollution. Identifying the source of water pollution is paramount to be able to effectively reduce contamination. The present study aimed to identify E. coli microbial source tracking (MST) markers that can be used to identify domestic wastewater contamination in environmental waters. We first analyzed wastewater E. coli genomes sequenced by us (n = 50) and RefSeq animal E. coli genomes of fecal origin (n = 82), and identified 144 candidate wastewater-associated marker genes. The sensitivity and specificity of the candidate marker genes were then assessed by screening the genes in 335 RefSeq wastewater E. coli genomes and 3318 RefSeq animal E. coli genomes. We finally identified two MST markers, namely W_nqrC and W_clsA_2, which could be used for detection of wastewater-associated E. coli isolates. These two markers showed higher performance than the previously developed human wastewater-associated E. coli markers H8 and H12. When used in combination, W_nqrC and W_clsA_2 showed specificity of 98.9 % and sensitivity of 25.7 %. PCR assays to detect W_nqrC and W_clsA_2 were also developed and validated. The developed PCR assays are potentially useful for detecting E. coli isolates of wastewater origin in environmental waters, though users should keep in mind that the sensitivity of these markers is not high. Further studies are needed to assess the applicability of the developed markers to a culture-independent approach.

Adherence of uropathogenic Escherichia coli in dog urine after consumption of food supplemented with cranberry (Vaccinium macrocarpon)

Introduction

Escherichia coli is the most common pathogen isolated from the urine of dogs with urinary tract infections (UTIs). While there are many studies in humans investigating the potential for the prevention of UTIs by dietary consumption of cranberry, few analogous studies have been carried out in dogs.

Material and Methods

Eight dogs, four male and four female, were successively fed two diets, first a control without cranberry, and then the second diet containing cranberry extracts. Naturally excreted urine was collected on the tenth day after the start of each diet for 24 h and used for bacterial growth. Madin-Darby canine kidney cell adherence by the uropathogenic E. coli G1473 strain expressing type 1 pili and positive for P pili and haemolysin gene markers was quantified after growth in urine samples.

Results

Significant reductions in bacterial adherence to MDCK cells (from −16.5 to −73.4%, P < 0.05) were observed in the four females but not in the males after consumption of the cranberry extracts compared to the same animals consuming the control diet.

Conclusion

Dietary supplementation with cranberry may provide some degree of protection to female dogs against adhesion of uropathogenic E. coli to urinary epithelial cells.

Urinary tract infection and sepsis causing potential of multidrug-resistant Extraintestinal pathogenic E. coli isolated from plant-origin foods

The dissemination of Extraintestinal pathogenic Escherichia coli (ExPEC) in food is a critical concern for human health and food safety. The present study is the first to systematically examine the diverse plant-origin foods such as cucumber, carrot, tomato, radish, chilli, fenugreek, coriander, peppermint, spring onion, cabbage, and spinach for the presence of ExPEC or specific putative ExPEC pathotypes with an in-depth assessment of their phylogenetics, virulence, and drug resistance. A total of 77 (15.9 %) ExPEC isolates were recovered from 1780 samples of the diverse plant-origin foods of distinct environments. Specific putative ExPEC pathotypes such as Uropathogenic E. coli (UPEC, 23.3 %) and Septicemia-associated E. coli (SEPEC, 24.6 %) were identified among ExPEC isolates. The Clermont revisited new phylotyping method revealed the varied distribution (1-27 %) of specific putative ExPEC pathotypes in the different phylogenetic lineages such as A, D/E, B1, and Clade 1, etc. All putative ExPEC pathotypes possess multiple genes (4.3-92.8 %) or phenotypes (3.3-100 %) associated with their virulence. In-vitro antimicrobial susceptibility testing of all putative ExPEC pathotypes demonstrated the presence of 100 % multidrug resistance with moderate to high (52-100 %) resistance to drugs used as last-resorts (chloramphenicol, colistin) or frontline (nitrofurantoin, sulfamethoxazole, ampicillin, gentamicin) in ExPEC-associated infections in humans. Overall, the present findings significantly contribute to our better understanding of the presence of ExPEC in the non-clinical niche, such as plant-origin foods with a possible consequence on human health and food safety.

Relevance of dog as an animal model for urologic diseases

We utilize animal models in urologic research to improve understanding of urinary physiology, determine the etiology of many urologic diseases, and discover and test novel therapeutic interventions. Dogs have a similar urinary tract anatomy and physiology to human and they develop many urologic diseases spontaneously. This chapter offers detailed comparisons of urinary tract anatomy, physiology, and the most common urologic diseases between humans and dogs. Dogs offer a unique opportunity for urologic research because they can be studied in research colonies and in client owned cohorts. Dogs also are among a limited number of non-human species that require continence and socially appropriate urinary behaviors (ex. going to the bathroom outside, training to not have submissive urination, etc.). These features make dogs unique in the animal kingdom and make them an ideal animal model for urologic research.

The microbial ecology of Escherichia coli in the vertebrate gut

Escherichia coli has a rich history as biology's 'rock star', driving advances across many fields. In the wild, E. coli resides innocuously in the gut of humans and animals but is also a versatile pathogen commonly associated with intestinal and extraintestinal infections and antimicrobial resistance-including large foodborne outbreaks such as the one that swept across Europe in 2011, killing 54 individuals and causing approximately 4000 infections and 900 cases of haemolytic uraemic syndrome. Given that most E. coli are harmless gut colonizers, an important ecological question plaguing microbiologists is what makes E. coli an occasionally devastating pathogen? To address this question requires an enhanced understanding of the ecology of the organism as a commensal. Here, we review how our knowledge of the ecology and within-host diversity of this organism in the vertebrate gut has progressed in the 137 years since E. coli was first described. We also review current approaches to the study of within-host bacterial diversity. In closing, we discuss some of the outstanding questions yet to be addressed and prospects for future research.

Fecal Shedding of Multidrug Resistant Escherichia coli Isolates in Dogs Fed with Raw Meat-Based Diets in Brazil

The practice of feeding dogs raw meat-based diets (RMBDs) is growing in several countries, and the risks associated with the ingestion of pathogenic and antimicrobial-resistant Escherichia coli in dogs fed these diets are largely unknown. We characterized E. coli strains isolated from dogs fed either an RMBD or a conventional dry feed, according to the phylogroup, virulence genes, and antimicrobial susceptibility profiles of the bacteria. Two hundred and sixteen E. coli strains were isolated. Dogs fed RMBDs shed E. coli strains from the phylogroup E more frequently and were positive for the E. coli heat-stable enterotoxin 1-encoding gene. Isolates from RMBD-fed dogs were also frequently positive for multidrug-resistant E. coli isolates including extended-spectrum beta-lactamase (ESBL) producers. Whole-genome sequencing of seven ESBL-producing E. coli strains revealed that they predominantly harbored blaCTX-M-55, and two strains were also positive for the colistin-resistant gene mcr-1. These results suggest that feeding an RMBD can affect the dog’s microbiota, change the frequency of certain phylogroups, and increase the shedding of diarrheagenic E. coli. Also, feeding an RMBD seemed to be linked with the fecal shedding of multidrug-resistant E. coli, including the spread of strains harboring mobilizable colistin resistance and ESBL genes. This finding is of concern for both animal and human health.

Antimicrobial resistance in bacterial isolates from companion animals in Buenos Aires, Argentina: 2011-2017 retrospective study

The widespread use of antimicrobial therapy in companion animals could lead to increased levels of resistance. Monitoring these levels is critical to understand not only the zoonotic threat of resistant bacteria but also the interspecies transmission of resistance mechanisms. However, data on resistance levels in companion animals of urban areas in Latin America are lacking. In this retrospective study, we analysed 23,922 isolates recovered from clinical samples of dogs and cats between 2011 and 2017. Growing trends of resistance to fluoroquinolones were observed in most bacterial species of veterinary importance with zoonotic potential (Enterobacterales, Pseudomonas and Staphylococcus). Furthermore, an increase of resistance levels to third-generation cephalosporins was also detected in Enterobacterales. Currently, Pseudomonas aeruginosa, Enterococcus spp. and Streptococcus spp. did not seem to represent a clinical challenge. A high proportion of multidrug-resistant (MDR) Enterobacterales isolated from urine was reported. It is interesting to outline that resistance to amikacin was exceptional. This study might be considered as a baseline for prospective antimicrobial resistance surveillance in companion animals in our region.

Antimicrobial drug resistance profile of isolated bacteria in dogs and cats with urologic problems at Chiang Mai University Veterinary Teaching Hospital, Thailand (2012-2016)

The present study aimed to estimate the proportion of bacterial urinary tract infection (UTI) in dogs and cats, assess risks associated with bacterial UTI, and to determine bacterial isolates' antimicrobial susceptibility and resistance pattern from the urinary tract of dogs and cats with urologic problems. The medical records from animals visiting Chiang Mai University Small Animal Veterinary Teaching Hospital between January 2012 and December 2016 were reviewed. In total, 203 dogs and 49 cats with urinary tract diseases that had samples submitted for bacterial culture were identified;198 and 24 bacterial isolates were recovered from dogs' and cats' submitted samples, respectively. At least one episode of bacterial UTI was detected in 75.4% (95% CI: 69.4-81.3) of dogs and in 40.8% (95% CI: 26.6-55.1) of cats with UTI and submitted urine cultures. Of 242 submitted urinary samples from dogs and 60 urinary samples from cats, bacteria were identified in 74.0% (95% CI: 68.4-79.5) and 38.3% (95% CI: 26.0-50.6), respectively. The most common pathogen of bacteria positive cultured from dogs was Staphylococcus spp. (30.3%), followed by Escherichia coli (16.7%), and Proteus spp. (13.6%). For cats, the most common pathogen was Pseudomonas spp. (25.0%), followed by E. coli (20.8%) and Proteus spp. (16.7%). Staphylococcus spp. isolates from dogs and Proteus spp. isolates from cats were highly susceptible to Amoxicillin/clavulanic acid (AMC) at 88% and 75%, respectively. Of all isolated bacteria, 67.1% of the bacteria from dogs and 83.3% from cats were multidrug-resistant (MDR). The proportion of MDR-bacterial urinary tract infections in dogs and cats with urologic problems in this study was high. This observation raises concerns regarding the potential of zoonotic transmission of MDR-bacteria from these companion animals. The results suggested that AMC remains a good empirical drug for treating UTIs in dogs in this region.

Whole-genome analyses of extended-spectrum or AmpC β-lactamase-producing Escherichia coli isolates from companion dogs in Japan

The emergence and global spread of extended-spectrum or AmpC β-lactamase (ESBL/AmpC)-producing Enterobacteriaceae in companion animals have led to the hypothesis that companion animals might be reservoirs for cross-species transmission because of their close contact with humans. However, current knowledge in this field is limited; therefore, the role of companion animals in cross-species transmission remains to be elucidated. Herein, we studied ESBL/AmpC-producing Enterobacteriaceae, Escherichia coli in particular, isolated from extraintestinal sites and feces of companion dogs. Whole-genome sequencing analysis revealed that (i) extraintestinal E. coli isolates were most closely related to those isolated from feces from the same dog, (ii) chromosomal sequences in the ST131/C1-M27 clade isolated from companion dogs were highly similar to those in the ST131/C1-M27 clade of human origin, (iii) certain plasmids, such as IncFII/pMLST F1:A2:B20/bla_CTX-M-27, IncI1/pMLST16/bla_CTX-M-15, or IncI1/bla_CMY-2 from dog-derived E. coli isolates, shared high homology with those from several human-derived Enterobacteriaceae, (iv) chromosomal bla_CTX-M-14 was identified in the ST38 isolate from a companion dog, and (v) eight out of 14 tested ESBL/AmpC-producing E. coli isolates (i.e., ST131, ST68, ST405, and ST998) belonged to the human extraintestinal pathogenic E. coli (ExPEC) group. All of the bla-coding plasmids that were sequenced genome-wide were capable of horizontal transfer. These results suggest that companion dogs can spread ESBL/AmpC-producing ExPEC via their feces. Furthermore, at least some ESBL/AmpC-producing ExPECs and bla-coding plasmids can be transmitted between humans and companion dogs. Thus, companion dogs can act as an important reservoir for ESBL/AmpC-producing E. coli in the community.

Environmental Spread of Extended Spectrum Beta-Lactamase (ESBL) Producing Escherichia coli and ESBL Genes among Children and Domestic Animals in Ecuador

BACKGROUND

There is a significant gap in our understanding of the sources of multidrug-resistant bacteria and resistance genes in community settings where human-animal interfaces exist.

OBJECTIVES

This study characterized the relationship of third-generation cephalosporin-resistant Escherichia coli (3GCR-EC) isolated from animal feces in the environment and child feces based on phenotypic antimicrobial resistance (AMR) and whole genome sequencing (WGS).

METHODS

We examined 3GCR-EC isolated from environmental fecal samples of domestic animals and child fecal samples in Ecuador. We analyzed phenotypic and genotypic AMR, as well as clonal relationships (CRs) based on pairwise single-nucleotide polymorphisms (SNPs) analysis of 3GCR-EC core genomes. CRs were defined as isolates with fewer than 100 different SNPs.

RESULTS

A total of 264 3GCR-EC isolates from children (n=21), dogs (n=20), and chickens (n=18) living in the same region of Quito, Ecuador, were identified. We detected 16 CRs total, which were found between 7 children and 5 domestic animals (5 CRs) and between 19 domestic animals (11 CRs). We observed that several clonally related 3GCR-EC isolates had acquired different plasmids and AMR genes. Most CRs were observed in different homes (n=14) at relatively large distances. Isolates from children and domestic animals shared the same blaCTX-M allelic variants, and the most prevalent were blaCTX-M-55 and blaCTX-M-65, which were found in isolates from children, dogs, and chickens.

DISCUSSION

This study provides evidence of highly dynamic horizontal transfer of AMR genes and mobile genetic elements (MGEs) in the E. coli community and shows that some 3GCR-EC and (extended-spectrum β-lactamase) ESBL genes may have moved relatively large distances among domestic animals and children in semirural communities near Quito, Ecuador. Child-animal contact and the presence of domestic animal feces in the environment potentially serve as important sources of drug-resistant bacteria and ESBL genes. https://doi.org/10.1289/EHP7729.

Distinguishing Pathovars from Nonpathovars: Escherichia coli

Escherichia coli is one of the most well-adapted and pathogenically versatile bacterial organisms. It causes a variety of human infections, including gastrointestinal illnesses and extraintestinal infections. It is also part of the intestinal commensal flora of humans and other mammals. Groups of E. coli that cause diarrhea are often described as intestinal pathogenic E. coli (IPEC), while those that cause infections outside of the gut are called extraintestinal pathogenic E. coli (ExPEC). IPEC can cause a variety of diarrheal illnesses as well as extraintestinal syndromes such as hemolytic-uremic syndrome. ExPEC cause urinary tract infections, bloodstream infection, sepsis, and neonatal meningitis. IPEC and ExPEC have thus come to be referred to as pathogenic variants of E. coli or pathovars. While IPEC can be distinguished from commensal E. coli based on their characteristic virulence factors responsible for their associated clinical manifestations, ExPEC cannot be so easily distinguished. IPEC most likely have reservoirs outside of the human intestine but it is unclear if ExPEC represent nothing more than commensal E. coli that breach a sterile barrier to cause extraintestinal infections. This question has become more complicated by the advent of whole genome sequencing (WGS) that has raised a new question about the taxonomic characterization of E. coli based on traditional clinical microbiologic and phylogenetic methods. This review discusses how molecular epidemiologic approaches have been used to address these questions, and how answers to these questions may contribute to our better understanding of the epidemiology of infections caused by E. coli. *This article is part of a curated collection.

Escherichia coli Residency in the Gut of Healthy Human Adults

Escherichia coli is one of the most well-studied bacterial species, but several significant knowledge gaps remain regarding its ecology and natural history. Specifically, the most important factors influencing its life as a member of the healthy human gut microbiome are either underevaluated or currently unknown. Distinct E. coli population dynamics have been observed over the past century from a handful of temporal studies conducted in healthy human adults. Early studies using serology up to the most recent studies using genotyping and DNA sequencing approaches have all identified long-lived E. coli residents and short-lived transients. This review summarizes these discoveries and other studies that focused on the underlying mechanisms that lead to establishment and maintenance of E. coli residency in healthy human adults. Many fundamental knowledge gaps remain and are highlighted with the hope of facilitating future studies in this exciting research area.

Epidemiology and genotypic characterisation of dissemination patterns of uropathogenic Escherichia coli in a community

To characterise the dissemination patterns of uropathogenic Escherichia coli (UPEC) in a community, we conducted a study utilising molecular and fundamental descriptive epidemiology. The subjects, consisted of women having community-acquired acute urinary tract infection (UTI), were enrolled in the study from 2011 to 2012. UPEC isolates were subjected to antibacterial-susceptibility testing, O serogrouping, phylotyping, multilocus-sequence typing with phylogenetic-tree analysis and pulsed-field-gel electrophoresis (PFGE). From the 209 unique positive urinary samples 166 UPEC were isolated, of which 129 were fully susceptible to the tested antibiotics. Of the 53 sequence types (STs), the four most prevalent STs (ST95, ST131, ST73 and ST357) accounted for 60% of all UPEC strains. Antimicrobial resistance was less frequently observed for ST95 and ST73 than for the others. A majority of rare STs and a few common STs constituted the diversity pattern within the population structure, which was composed of the two phylogenetically distinct clades. Eleven genetically closely related groups were determined by PFGE, which accounted for 42 of the 166 UPEC isolates, without overt geo-temporal clustering. Our results indicate that a few major lineages of UPEC, selected by unidentified factors, are disseminated in this community and contribute to a large fraction of acute UTIs.

Differentiating Epidemic from Endemic or Sporadic Infectious Disease Occurrence

One important scope of work of epidemiology is the investigation of infectious diseases that cluster in time and place. Clusters of infectious disease may represent outbreaks or epidemics in which the cases share in common a point source exposure or an infectious agent in a chain of transmission pathways. Investigations of outbreaks of an illness can facilitate identification of a source, risk, or cause of the illness. However, most infectious disease episodes occur not as part of any apparent outbreaks but as sporadic infections. Multiple sporadic infections that occur steadily in time and place are referred to as endemic disease. How does one investigate sources and risk factors for sporadic or endemic infections? As part of the Microbiology Spectrum Curated Collection: Advances in Molecular Epidemiology of Infectious Diseases, this review discusses limitations of traditional approaches and advantages of molecular epidemiology approaches to investigate sporadic and endemic infections. Using specific examples, the discussions show that most sporadic infections are actually part of unrecognized outbreaks and that what appears to be endemic disease occurrence is actually comprised of multiple small outbreaks. These molecular epidemiologic investigations have unmasked modes of transmission of infectious agents not known to cause outbreaks. They have also raised questions about the traditional ways to measure incidence and assess sources of drug-resistant infections in community settings. The discoveries made by the application of molecular microbiology methods in epidemiologic investigations have led to creation of new public health intervention strategies that have not been previously considered. *This article is part of a curated collection.

Identification and Characterization of Escherichia coli, Salmonella Spp., Clostridium perfringens, and C. difficile Isolates from Reptiles in Brazil

Considering the increasing popularity of reptiles as pets and their possible role as reservoirs of pathogenic microorganisms, the aim of this study was to isolate Escherichia coli, Salmonella spp., Clostridium perfringens, and C. difficile strains from reptiles in Brazil and to characterize the isolated strains. The characterization was based on phylogenetic typing of E. coli, identification of virulence genes of E. coli, C. perfringens, and C. difficile, serotyping of Salmonella spp., ribotyping and MLST of C. difficile and antimicrobial susceptibility test of pathogenic strains. Cloacal swabs were collected from 76 reptiles, of which 15 were lizards, 16 chelonians, and 45 snakes, either living in captivity, in the wild, or as companion animals. E. coli was isolated from 52 (68.4%) reptiles, of which 46 (88.4%) were characterized as phylogroup B1. The virulence factor CNF1 of E. coli was found in seven (9.2%) sampled animals, whereas the gene of EAST1 was found in isolates from two (2.6%) reptiles. Three isolates positive for CNF1 were resistant to cephalothin, one of which was also resistant to ciprofloxacin, trimethoprim/sulfamethoxazole, and chloramphenicol, being then classified as multidrug resistant strain (MDR). Salmonella enterica was identified in 26 (34.2%) reptiles, of which 13 belonged to the subspecies enterica. Serotypes such as S. Mbandaka, S. Panama, S. Infantis, S. Heidelberg, and S. Anatum were identified. One isolate of S. enterica subsp. houtenae was resistant to cephalothin and ciprofloxacin. C. perfringens type A was isolated from six (7.8%) animals. C. difficile was isolated from three (3.9%) reptiles. Two of these isolates were toxigenic and classified into ribotypes/MLST 081/ST9 and 106/ST42, which have been previously reported to infect humans. In conclusion, reptiles in Brazil can harbor toxigenic C. difficile and potentially pathogenic E. coli and Salmonella enterica subsp. enterica, thus representing a risk to human and animal health.

Evidence of Sharing of Klebsiella pneumoniae Strains between Healthy Companion Animals and Cohabiting Humans

This study aimed to characterize the fecal colonization and sharing of Klebsiella pneumoniae strains between companion animals and humans living in close contact. Fecal samples were collected from 50 healthy participants (24 humans, 18 dogs, and 8 cats) belonging to 18 households. Samples were plated onto MacConkey agar (MCK) plates with and without cefotaxime or meropenem supplementation. Up to five K. pneumoniae colonies per participant were compared by pulsed-field gel electrophoresis (PFGE) after XbaI restriction. K. pneumoniae strains with unique pulse types from each participant were characterized for antimicrobial susceptibility, virulence genes, and multilocus sequence type (MLST). Fecal K. pneumoniae pulse types were compared to those of clinical K. pneumoniae strains from animal and human patients with urinary tract infections (n = 104). K. pneumoniae colonization was detected in nonsupplemented MCK in around 38% of dogs (n = 7) and humans (n = 9). K. pneumoniae strains isolated from dogs belonged to sequence type 17 (ST17), ST188, ST252, ST281, ST423, ST1093, ST1241, ST3398, and ST3399. None of the K. pneumoniae strains were multidrug resistant or hypervirulent. Two households included multiple colonized participants. Notably, two colonized dogs within household 15 (H15) shared a strain each (ST252 and ST1241) with one coliving human. One dog from H16 shared one PFGE-undistinguishable K. pneumoniae ST17 strain with two humans from different households; however, the antimicrobial susceptibility phenotypes of these three strains differed. Two main virulence genotypes were detected, namely fimH-1 mrkD ycfM entB kfu and fimH-1 mrkD ycfM entB kpn These results highlight the potential role of dogs as a reservoir of K. pneumoniae to humans and vice versa. Furthermore, to our best knowledge, this is the first report of healthy humans and dogs sharing K. pneumoniae strains that were undistinguishable by PFGE/MLST.

Diverse Commensal Escherichia coli Clones and Plasmids Disseminate Antimicrobial Resistance Genes in Domestic Animals and Children in a Semirural Community in Ecuador

The increased prevalence of antimicrobial resistance (AMR) among Enterobacteriaceae has had major clinical and economic impacts on human medicine. Many of the multidrug-resistant (multiresistant) Enterobacteriaceae found in humans are community acquired, and some of them are possibly linked to food animals (i.e., livestock raised for meat and dairy products). In this study, we examined whether numerically dominant commensal Escherichia coli strains from humans (n = 63 isolates) and domestic animals (n = 174 isolates) in the same community and with matching phenotypic AMR patterns were clonally related or shared the same plasmids. We identified 25 multiresistant isolates (i.e., isolates resistant to more than one antimicrobial) that shared identical phenotypic resistance patterns. We then investigated the diversity of E. coli clones, AMR genes, and plasmids carrying the AMR genes using conjugation, replicon typing, and whole-genome sequencing. All of the multiresistant E. coli isolates (from children and domestic animals) analyzed had at least 90 or more whole-genome SNP differences between one another, suggesting that none of the strains was recently transferred. While the majority of isolates shared the same antimicrobial resistance genes and replicons, DNA sequencing indicated that these genes and replicons were found on different plasmid structures. We did not find evidence of the clonal spread of AMR in this community: instead, AMR genes were carried on diverse clones and plasmids. This presents a significant challenge for understanding the movement of AMR in a community.IMPORTANCE Even though Escherichia coli strains may share nearly identical phenotypic AMR profiles and AMR genes and overlap in space and time, the diversity of clones and plasmids challenges research that aims to identify sources of AMR. Horizontal gene transfer appears to play a more significant role than clonal expansion in the spread of AMR in this community.

No. 250-Recurrent Urinary Tract Infection

OBJECTIVE

To provide an update of the definition, epidemiology, clinical presentation, investigation, treatment, and prevention of recurrent urinary tract infections in women.

OPTIONS

Continuous antibiotic prophylaxis, post-coital antibiotic prophylaxis, and acute self-treatment are all efficient alternatives to prevent recurrent urinary tract infection. Vaginal estrogen and cranberry juice can also be effective prophylaxis alternatives.

EVIDENCE

A search of PubMed and The Cochrane Library for articles published in English identified the most relevant literature. Results were restricted to systematic reviews, randomized control trials/controlled clinical trials, and observational studies. There were no date restrictions.

VALUES

This update is the consensus of the Sub-Committee on Urogynaecology of the Society of Obstetricians and Gynaecologists of Canada. Recommendations were made according to the guidelines developed by the Canadian Task Force on Preventive Health Care (Table 1).

OPTIONS

Recurrent urinary tract infections need careful investigation and can be efficiently treated and prevented. Different prophylaxis options can be selected according to each patient's characteristics.

RECOMMENDATIONS

Virulence factors, antibiotic resistance genes and genetic relatedness of commensal Escherichia coli isolates from dogs and their owners

Escherichia coli (E. coli) is a normal flora of gastrointestinal tracts of humans and warm-blooded animals including dogs that has close vicinity with humans. Because the inter-species transmission of E. coli between pets and human beings, within a household, obtaining more information about the epidemiology, genetics, virulence factors, and antibiotic resistance of E. coli from dogs and their owners will help to control the inter-species transmission and treatment of E. coli infections. In this study we characterize and compare the antibiotic resistance and virulence profiles of fecal E. coli isolates from dogs and their owners. A total of 149 commensal E. coli isolates comprised 62 isolates from dogs, 56 isolates from their owners and 31 isolates from humans with no pet as control were collected. Extracted DNA was assessed for the presence of antibiotic resistance genes cmlA (chloramphenicol), sulI (sulfamethoxazole), floR (florfenicol) and blaCTX-M1 (cefotaxime) and virulence genes (papA, ompT, hlyD, traT, tsh and cnf1). To determine the extent of genetic relatedness of isolates, RAPD-PCR was performed. sulI and traT genes were the most dominant resistance profile and the most prevalent virulence gene in all groups, respectively, while hlyD had the lowest frequency among investigated virulence genes. Based on RAPD-PCR analysis clonal sharing between dogs and their owners were observed in 2/28 (7.1%) potential within-household clone-sharing pairs. Allowing dog to lick on owner's face, dog sex (female dogs), dog's sexual status (intact dogs) and times of disposing the feces (≥twice a day) were associated with a higher percentage of RAPD profile similarity (P < 0.05). The current study did not show an obvious evidence to prove considerable transmission of fecal E. coli from dogs to their owners. But in two households, there were relationship between isolates from dogs and their owners.

Risk factors for acquisition of multidrug-resistant Escherichia coli and development of community-acquired urinary tract infections

We examined risk factors associated with the intestinal acquisition of antimicrobial-resistant extraintestinal pathogenic Escherichia coli (ExPEC) and development of community-acquired urinary tract infection (UTI) in a case-control study of young women across Canada. A total of 399 women were recruited; 164 women had a UTI caused by E. coli resistant to ⩾1 antimicrobial classes and 98 had a UTI caused by E. coli resistant to ⩾3 antimicrobial classes. After adjustment for age, student health service (region of Canada) and either prior antibiotic use or UTI history, consumption of processed or ground chicken, cooked or raw shellfish, street foods and any organic fruit; as well as, contact with chickens, dogs and pet treats; and travel to Asia, were associated with an increased risk of UTI caused by antimicrobial resistant E. coli. A decreased risk of antimicrobial resistant UTI was associated with consumption of apples, nectarines, peppers, fresh herbs, peanuts and cooked beef. Drug-resistant UTI linked to foodborne and environmental exposures may be a significant public health concern and understanding the risk factors for intestinal acquisition of existing or newly emerging lineages of drug-resistant ExPEC is important for epidemiology, antimicrobial stewardship and prevention efforts.

Pathoadaptive Mutations in Uropathogenic Escherichia coli

Uropathogenic Escherichia coli (UPEC) are opportunistic human pathogens that primarily circulate as part of commensal intestinal microbiota. Though they have the ability to survive and proliferate in various urinary tract compartments, the urinary tract is a transient, occasional habitat for UPEC. Because of this, most of the UPEC traits have originally evolved to serve in intestinal colonization and transmission. Some of these bacterial traits serve as virulence factors - they are critical to or assist in survival of UPEC as pathogens, and the structure and/or function may be specialized for the infection. Other traits could serve as anti-virulence factors - they represent liability in the urinary tract and are under selection to be lost or inactivated during the infection. Inactivation, variation, or other changes of the bacterial genes that increase the pathogen's fitness during the infection are called pathoadaptive mutations. This chapter describes examples of pathoadaptive mutations in UPEC and provides rationale for their further in-depth study.

Population Phylogenomics of Extraintestinal Pathogenic Escherichia coli

The emergence of genomics over the last 10 years has provided new insights into the evolution and virulence of extraintestinal Escherichia coli. By combining population genetics and phylogenetic approaches to analyze whole-genome sequences, it became possible to link genomic features to specific phenotypes, such as the ability to cause urinary tract infections. An E. coli chromosome can vary extensively in length, ranging from 4.3 to 6.2 Mb, encoding 4,084 to 6,453 proteins. This huge diversity is structured as a set of less than 2,000 genes (core genome) that are conserved between all the strains and a set of variable genes. Based on the core genome, the history of the species can be reliably reconstructed, revealing the recent emergence of phylogenetic groups A and B1 and the more ancient groups B2, F, and D. Urovirulence is most often observed in B2/F/D group strains and is a multigenic process involving numerous combinations of genes and specific alleles with epistatic interactions, all leading down multiple evolutionary paths. The genes involved mainly code for adhesins, toxins, iron capture systems, and protectins, as well as metabolic pathways and mutation-rate-control systems. However, the barrier between commensal and uropathogenic E. coli strains is difficult to draw as the factors that are responsible for virulence have probably also been selected to allow survival of E. coli as a commensal in the intestinal tract. Genomic studies have also demonstrated that infections are not the result of a unique and stable isolate, but rather often involve several isolates with variable levels of diversity that dynamically changes over time.

European multicenter study on antimicrobial resistance in bacteria isolated from companion animal urinary tract infections

BACKGROUND

There is a growing concern regarding the increase of antimicrobial resistant bacteria in companion animals. Yet, there are no studies comparing the resistance levels of these organisms in European countries. The aim of this study was to investigate geographical and temporal trends of antimicrobial resistant bacteria causing urinary tract infection (UTI) in companion animals in Europe. The antimicrobial susceptibility of 22 256 bacteria isolated from dogs and cats with UTI was determined. Samples were collected between 2008 and 2013 from 16 laboratories of 14 European countries. The prevalence of antimicrobial resistance of the most common bacteria was determined for each country individually in the years 2012-2013 and temporal trends of bacteria resistance were established by logistic regression.

RESULTS

The aetiology of uropathogenic bacteria differed between dogs and cats. For all bacterial species, Southern countries generally presented higher levels of antimicrobial resistance compared to Northern countries. Multidrug-resistant Escherichia coli were found to be more prevalent in Southern countries. During the study period, the level of fluoroquinolone-resistant E. coli isolated in Belgium, Denmark, France and the Netherlands decreased significantly. A temporal increase in resistance to amoxicillin-clavulanate and gentamicin was observed among E. coli isolates from the Netherlands and Switzerland, respectively. Other country-specific temporal increases were observed for fluoroquinolone-resistant Proteus spp. isolated from companion animals from Belgium.

CONCLUSIONS

This work brings new insights into the current status of antimicrobial resistance in bacteria isolated from companion animals with UTI in Europe and reinforces the need for strategies aiming to reduce resistance.

Reservoirs of Extraintestinal Pathogenic Escherichia coli

Several potential reservoirs for the Escherichia coli strains that cause most human extraintestinal infections (extraintestinal pathogenic E. coli; ExPEC) have been identified, including the human intestinal tract and various non-human reservoirs, such as companion animals, food animals, retail meat products, sewage, and other environmental sources. Understanding ExPEC reservoirs, chains of transmission, transmission dynamics, and epidemiologic associations will assist greatly in finding ways to reduce the ExPEC-associated disease burden. The need to clarify the ecological behavior of ExPEC is all the more urgent because environmental reservoirs may contribute to acquisition of antimicrobial resistance determinants and selection for and amplification of resistant ExPEC. In this chapter, we review the evidence for different ExPEC reservoirs, with particular attention to food and food animals, and discuss the public health implications of these reservoirs for ExPEC dissemination and transmission.

Risk factors for carriage of antimicrobial-resistant Salmonella spp and Escherichia coli in pet dogs from volunteer households in Ontario, Canada, in 2005 and 2006

OBJECTIVE To determine pet-related management factors associated with the carriage of antimicrobial-resistant Salmonella spp and Escherichia coli in a population of pet dogs. SAMPLE 138 dogs from 84 households in Ontario, Canada. PROCEDURES From October 2005 through May 2006, dogs and households in Ontario, Canada, were recruited to participate in a cross-sectional study. Fecal samples were submitted for culture of Salmonella spp and E coli, which provided 515 bacterial isolates for antimicrobial susceptibility testing. Multilevel logistic regression models with random effects for household and dog were created to identify pet-related management factors associated with antimicrobial resistance. RESULTS Bacterial species, feeding a homemade diet or adding homemade food to the diet, feeding a raw diet or adding anything raw to the diet, feeding a homemade raw food diet, and feeding raw chicken in the past week were significant risk factors for antimicrobial resistance in this population of dogs. CONCLUSIONS AND CLINICAL RELEVANCE In this study, several potentially important pet-related risk factors for the carriage of antimicrobial-resistant Salmonella spp and E coli in pet dogs were identified. Further evaluation of risk factors for antimicrobial resistance in dogs may lead to development of evidence-based guidelines for safe and responsible dog ownership and management to protect the public, especially pet owners who are immunocompromised.

Evidence of household transfer of ESBL-/pAmpC-producing Enterobacteriaceae between humans and dogs - a pilot study

Background

Extended-spectrum cephalosporin-resistant Enterobacteriaceae (ESCRE) are an increasing healthcare problem in both human and veterinary medicine. The spread of ESCRE is complex with multiple reservoirs and different transmission routes. The aim of this study was to investigate if ESCRE carriage in dogs is more prevalent in households with a known human carrier, compared to households where humans are known to be negative for ESCRE. Identical ESCRE strains in humans and dogs of the same household would suggest a possible spread between humans and dogs.

Methods

Twenty-two dog owners with a positive rectal culture for ESCRE each collected a rectal sample from their dog. In addition, a control group of 29 healthy dog owners with a documented negative rectal culture for ESCRE each sampled their household dog. Samples were cultivated for ESCRE using selective methods. In households where both humans and dogs carried ESCRE, isolates were further analysed for antimicrobial susceptibility by disc diffusion or microdilution and for genotype and genetic relatedness using molecular methods.

Results

In 2 of 22 households studied, identical ESCRE strains with respect to bacterial species, antibiogram, genotype, and MLVA type were found in humans and dogs. The ESCRE found in the two households were ESBL-producing E. coli with the resistance gene bla_CTX-M-27 and AmpC-producing E. coli with bla_CMY-2, bla_TEM-1. ESCRE were not found in dogs in the control group.

Conclusions

In households where humans are carrying ESCRE, identical strains were to a limited extent found also in household dogs, indicating a transfer between humans and dogs. In contrast, ESCRE were not found in dogs in households without human carriers.

DNA fingerprinting approaches to trace Escherichia coli sharing between dogs and owners

AIMS

To determine the prevalence of cross-species sharing of Escherichia coli between healthy dogs and humans living in the same household.

METHODS AND RESULTS

Two faecal E. coli isolates from 25 healthy dog-owner pairs and 16 healthy control humans were tested using three fingerprinting methods. The prevalence of within-household sharing of E. coli was 4, 8 and 8% using pulsed-field gel electrophoresis, randomly amplified polymorphic DNA and enterobacterial repetitive intergenic consensus-PCR analyses respectively. Within-household bacterial sharing was more prevalent than across-household sharing (P < 0·05). According to questionnaire analyses avoiding the dog-owner behaviours such as allowing a dog to kiss or lick the owner's face, sharing people food with dog and feeding it raw meat may decrease the chance of cross-species E. coli sharing.

CONCLUSIONS

Direct contact between humans and dogs and environmental reservoirs may be important routes for cross-species sharing of bacteria. Good personal hygiene and appropriate veterinary care for pets can minimize this risk.

SIGNIFICANCE AND IMPACT OF THE STUDY

Due to the importance of canine pathogenic E. coli reservoir hypothesis, close contacts between humans and dogs raises public health concerns. Determining the rate of cross-species bacterial sharing and confirm its accuracy by different fingerprinting techniques will help to find ways for reducing the economic impact of E. coli infections. This study support claims that public health concerns regarding the cross-species sharing of E. coli are warranted but this risk is minimal.

Multilocus Sequence Typing and Virulence Profiles in Uropathogenic Escherichia coli Isolated from Cats in the United States

The population structure, virulence, and antimicrobial resistance of uropathogenic E. coli (UPEC) from cats are rarely characterized. The aim of this study was to compare and characterize the UPEC isolated from cats in four geographic regions of USA in terms of their multilocus sequence typing (MLST), virulence profiles, clinical signs, antimicrobial resistance and phylogenetic grouping. The results showed that a total of 74 E. coli isolates were typed to 40 sequence types with 10 being novel. The most frequent phylogenetic group was B2 (n = 57). The most frequent sequence types were ST73 (n = 12) and ST83 (n = 6), ST73 was represented by four multidrug resistant (MDR) and eight non-multidrug resistant (SDR) isolates, and ST83 were significantly more likely to exhibit no drug resistant (NDR) isolates carrying the highest number of virulence genes. Additionally, MDR isolates were more diverse, and followed by SDR and NDR isolates in regards to the distribution of the STs. afa/draBC was the most prevalent among the 29 virulence-associated genes. Linking virulence profile and antimicrobial resistance, the majority of virulence-associated genes tested were more prevalent in NDR isolates, and followed by SDR and MDR isolates. Twenty (50%) MLST types in this study have previously been associated with human isolates, suggesting that these STs are potentially zoonotic. Our data enhanced the understanding of E. coli population structure and virulence association from cats. The diverse and various combinations of virulence-associated genes implied that the infection control may be challenging.

Characterization of Pathogenic Escherichia coli in River Water by Simultaneous Detection and Sequencing of 14 Virulence Genes

The occurrence of pathogenic Escherichia coli in environmental waters increases the risk of waterborne disease. In this study, 14 virulence genes in 669 E. coli isolates (549 isolates from the Yamato River in Japan, and 30 isolates from each of the following hosts: humans, cows, pigs, and chickens) were simultaneously quantified by multiplex PCR and dual index sequencing to determine the prevalence of potentially pathogenic E. coli. Among the 549 environmental isolates, 64 (12%) were classified as extraintestinal pathogenic E. coli (ExPEC) while eight (1.5%) were classified as intestinal pathogenic E. coli (InPEC). Only ExPEC-associated genes were detected in human isolates and pig isolates, and 11 (37%) and five (17%) isolates were classified as ExPEC, respectively. A high proportion (63%) of cow isolates possessed Shiga-toxin genes (stx1 or stx2) and they were classified as Shiga toxin-producing E. coli (STEC) or enterohemorrhagic E. coli (EHEC). Among the chicken isolates, 14 (47%) possessed iutA, which is an ExPEC-associated gene. This method can determine the sequences as well as the presence/absence of virulence genes. By comparing the sequences of virulence genes, we determined that sequences of iutA were different among sources and may be useful for discriminating isolates, although further studies including larger numbers of isolates are needed. Results indicate that humans are a likely source of ExPEC strains in the river.

Colonization with Escherichia coli Strains among Female Sex Partners of Men with Febrile Urinary Tract Infection

Of 23 unique Escherichia coli strains from 10 men with febrile urinary tract infections (UTIs) and their female sex partners, 6 strains (all UTI causing) were shared between partners. Molecularly, the 6 shared strains appeared more virulent than the 17 nonshared strains, being associated with phylogenetic group B2, sequence types ST73 and ST127, and multiple specific virulence genes. This indicates that UTIs are sometimes sexually transmitted.

Extensive Household Outbreak of Urinary Tract Infection and Intestinal Colonization due to Extended-Spectrum β-Lactamase-Producing Escherichia coli Sequence Type 131

BACKGROUND

Reasons for the successful global dissemination of multidrug-resistant Escherichia coli sequence type 131 (ST131) are undefined, but may include enhanced transmissibility or ability to colonize the intestine compared with other strains.

METHODS

We identified a household in which 2 young children had urinary tract infection (UTI) caused by an extended-spectrum β-lactamase (ESBL)-producing, multidrug-resistant ST131 E. coli strain. We assessed the prevalence of ST131 intestinal colonization among the 7 household members (6 humans, 1 dog). Fecal samples, collected 3 times over a 19-week period, were cultured selectively for E. coli. Isolates were characterized using clone-specific polymerase chain reaction to detect ST131 and its ESBL-associated H30Rx subclone, pulsed-field gel electrophoresis, extended virulence genotyping, and antimicrobial susceptibility testing.

RESULTS

In total, 8 different E. coli pulsotypes (strains) were identified. The index patient's urine isolate represented ST131-H30Rx strain 903. This was the most widely shared and persistent strain in the household, colonizing 5 individuals at each sampling. In contrast, the 7 non-ST131 strains were each found in only 1 or 2 household members at a time, with variable persistence. The ST131 strain was the only strain with both extensive virulence and antimicrobial resistance profiles.

CONCLUSIONS

An ESBL-producing ST131-H30Rx strain caused UTI in 2 siblings, plus asymptomatic intestinal colonization in multiple other household members, and was the household's most extensively detected and persistent fecal E. coli strain. Efficient transmission and intestinal colonization may contribute to the epidemiologic success of the H30Rx subclone of E. coli ST131.

Escherichia coli ST131, an intriguing clonal group

In 2008, a previously unknown Escherichia coli clonal group, sequence type 131 (ST131), was identified on three continents. Today, ST131 is the predominant E. coli lineage among extraintestinal pathogenic E. coli (ExPEC) isolates worldwide. Retrospective studies have suggested that it may originally have risen to prominence as early as 2003. Unlike other classical group B2 ExPEC isolates, ST131 isolates are commonly reported to produce extended-spectrum β-lactamases, such as CTX-M-15, and almost all are resistant to fluoroquinolones. Moreover, ST131 E. coli isolates are considered to be truly pathogenic, due to the spectrum of infections they cause in both community and hospital settings and the large number of virulence-associated genes they contain. ST131 isolates therefore seem to contradict the widely held view that high levels of antimicrobial resistance are necessarily associated with a fitness cost leading to a decrease in pathogenesis. Six years after the first description of E. coli ST131, this review outlines the principal traits of ST131 clonal group isolates, based on the growing body of published data, and highlights what is currently known and what we need to find out to provide public health authorities with better information to help combat ST131.

Fecal source tracking in water by next-generation sequencing technologies using host-specific Escherichia coli genetic markers

High levels of fecal bacteria are a concern for the aquatic environment, and identifying sources of those bacteria is important for mitigating fecal pollution and preventing waterborne disease. Escherichia coli has been used as an indicator of fecal pollution, however less success has been achieved using this organism for library-independent microbial source tracking. In this study, using next-generation sequencing technology we sequenced the whole genomes of 22 E. coli isolates from known sources (9 from humans, 2 from cows, 6 from pigs, and 5 from chickens) and identified candidate host-specific genomic regions. Specificity testing on the candidate regions was performed using 30 E. coli isolates from each source. Finally, we identified 4 human-, 2 cow-, 3 pig-, and 4 chicken-specific genetic markers useful for source tracking. We also found that a combination of multiplex PCR and dual index sequencing is effective for detecting multiple genetic markers in multiple isolates at one time. This technique was applied to investigating identified genetic markers in 549 E. coli isolates obtained from the Yamato River, Japan. Results indicate that humans constitute a major source of water contamination in the river. However, further work must include isolates obtained from geographically diverse animal hosts to make this method more reliable.

Virulence genotypes, antibiotic resistance and the phylogenetic background of extraintestinal pathogenic Escherichia coli isolated from urinary tract infections of dogs and cats in Brazil

Urinary tract infection (UTI) is a frequent disease of humans and pets and has extra-intestinal pathogenic Escherichia coli (ExPEC) strains as one of the main etiologic agent. ExPEC are characterized by specific virulence factors and are related to a heterogeneous group of human and animal disorders, besides to be a relevant participant in the dissemination of antimicrobial resistance. The purpose of this study was to characterize E. coli strains isolated from UTI of dogs and cats for serotypes, virulence markers, phylogenetic groups and sensitivity to antimicrobial drugs. E. coli was identified as the etiologic agent of UTI in urine samples of 43 pets (7 cats and 36 dogs). Serogroups O2, O4 and O6 corresponded to more than one third of the isolates, being 62% of the total strains classified as B2, 18% as D, 16% as B1 and 4% as A. The iucD (22%), fyuA (80%), traT (51%) and cvaC (20%) genes were distributed among the four phylogenetic groups, whereas the papC/papEF (47%) and malX (67%) genes were found only in groups B2 and D. There were a high number of resistant strains, with 76% of the strains belonging to groups A, B1 and D characterized as multidrug resistant (MDR), whereas only 21% had this phenotype in the group B2. The ExPEC strains isolated in this study displayed pathotypic and phylogenetic similarities with human isolates and high percentages of drug resistance. The finding of MDR ExPEC strains suggests implications for animal and public health and deserves more investigations.

Synchrotron X-ray fluorescence microscopy of gallium in bladder tissue following gallium maltolate administration during urinary tract infection

A mouse model of cystitis caused by uropathogenic Escherichia coli was used to study the distribution of gallium in bladder tissue following oral administration of gallium maltolate during urinary tract infection. The median concentration of gallium in homogenized bladder tissue from infected mice was 1.93 μg/g after daily administration of gallium maltolate for 5 days. Synchrotron X-ray fluorescence imaging and X-ray absorption spectroscopy of bladder sections confirmed that gallium arrived at the transitional epithelium, a potential site of uropathogenic E. coli infection. Gallium and iron were similarly but not identically distributed in the tissues, suggesting that at least some distribution mechanisms are not common between the two elements. The results of this study indicate that gallium maltolate may be a suitable candidate for further development as a novel antimicrobial therapy for urinary tract infections caused by uropathogenic E. coli.