Risk factors for the occurrence of Escherichia coli virulence genes eae , stx1 and stx2 in wild bird populations

Occurrence of virulence genes in multidrug-resistant Escherichia coli isolates from humans, animals, and the environment: One health perspective

Escherichia coli is one of the critical One Health pathogens due to its vast array of virulence and antimicrobial resistance genes. This study used multiplex PCR to determine the occurrence of virulence genes bfp, ompA, traT, eaeA, and stx1 among 50 multidrug-resistant (MDR) E. coli isolates from humans (n = 15), animals (n = 29), and the environment (n = 6) in Dar es Salaam, Tanzania. Their association with antimicrobial-resistant genes (ARGs) was determined using Principal Component Analysis (PCA). All 50/50 (100%) MDR E. coli isolates carried at least one virulence gene, with 19/50 (38%) carrying four genes, bfp + traT + eaeA + ompA. The findings showed a high occurrence of virulence genes bfp (82%), traT (82%), eaeA (78%), and ompA (72%); the study detected no stx1 in any of the isolates. In humans, the most detected virulence genes were bfp and traT 14/15 (93.3%); for poultry, it was eaeA 13/14 (92.9%); for pigs, was bfp and traT 13/15 (86.7%); while for river water, it was eaeA 6/6 (100%). The study observed no significant association between virulence genes and ARGs. PCA results show the genes ompA, traT, eaeA, and bfp contributed to the virulence of the isolates, and blaTEM, blaCTX-M, and qnrs contributed to ARGs. The PCA ellipses show that isolates from pigs had more virulence genes than those isolated from poultry, river water, and humans. The high frequency of numerous virulence genes in MDR E. coli isolates from humans, animals, and the environment indicates that these isolates have a very high potential to cause diseases that are difficult to treat because they are MDR.

Risks of foodborne pathogens associated with animal contamination of raw-agricultural commodities: A review

Pathogens that cause foodborne illness can contaminate raw-agricultural produce via animal intrusion and defecation in production fields. The Food and Drug Administration's Produce Safety Rule and related guidance cite published research on animal intrusion risk and risk-reduction practices. However, additional relevant research has been published since their release. Research on animal contamination often focuses on a single risk factor. This review summarizes current research on multiple risk factors and provides a basis for understanding how these factors may interact to influence risk to produce from animal contamination, providing regulators and educators with science-based information to inform education and outreach to growers. This review may also aid researchers by identifying future research needs. We conclude that when managing risks from animal contamination, a multi-pronged approach is necessary. This approach considers a range of factors, including animal type, nature of feces, rain and irrigation events, meteorology, and worker training. We also created an online tool that conveys the findings of this review in a succinct and digestible format for growers and regulatory and educational partners.

Antimicrobial Resistance and Pathotypes of Escherichia coli Isolates from Yellow-Legged Seagulls (Larus michahellis) in Central Italy

Seagulls are synanthropic wild birds that can contaminate, through their droppings, beaches, urban and peri-urban environments. This concern is more serious when seagulls eliminate antimicrobial-resistant pathogenic bacteria. This study analyzed the fecal samples from 137 yellow-legged seagulls (Larus michahellis) from Central Italy. A total of 218 Escherichia coli strains were isolated and analyzed for phenotypic and genotypic antimicrobial resistance and to identify the virulence genes characterizing different pathotypes. The disk diffusion method on all isolates found relevant resistance rates to ampicillin (38.99%), tetracycline (23.85%), and enrofloxacin (21.10%). On the basis of all results obtained with this test, 62 (28.44%) isolates were classified as multidrug-resistant (MDR) and 6 (2.75%) as extensive drug-resistant (XDR). Molecular analyses conducted on the strains phenotypically resistant to carbapenems, cephalosporins, and penicillins found 9/37 (24.32%) strains positive for blaOXA-48, 52/103 (50.49%) for blaTEM, 12/103 (11.65%) for blaCMY2, 3/103 (2.91%) for blaCTX, and 1/103 (0.97%,) for blaSHV. PCR to detect virulence genes characterizing different pathotypes found that 40 (18.35%) isolates had the astA gene, indicative of the enteroaggregative (EAEC) pathotype, 2 (0.92%) had cnf1, 2 (0.92%) had cnf2, and 1 (0.46%) had cdt-IV. All five (2.29%) strains were reportable as necrotoxigenic (NTEC), while 4 (1.83%) had both eaeA and escV, reportable as enteropathogenic (EPEC). Measures to limit seagulls' access where humans and other animals reside are pivotal to reduce the risk of infection with antimicrobial-resistant and pathogenetic E. coli strains.

Genotypic and Phenotypic Characterization of Pathogenic Escherichia coli, Salmonella spp., and Campylobacter spp., in Free-Living Birds in Mainland Portugal

Birds are potential carriers of pathogens affecting humans and agriculture. Aiming to evaluate the occurrence of the top three most important foodborne pathogens in free-living birds in Portugal, we investigated 108 individual fecal samples from free-living birds and one pooled sample of gull feces (n = 50) for the presence of Escherichia coli (pathogenic and non-pathogenic), Salmonella spp. and Campylobacter spp. Virulence- and antimicrobial resistance- (AMR) associated genes were detected by PCR and Whole-Genome Sequencing (WGS), and phenotypic (serotyping and AMR profiles) characterization was performed. Overall, 8.9% of samples tested positive for pathogenic E. coli, 2.8% for Salmonella spp., and 9.9% for Campylobacter spp. AMR was performed on all pathogenic isolates and in a fraction of non-pathogenic E. coli, being detected in 25.9% of them. Ten of the tested E. coli isolates were multidrug-resistant (MDR), and seven of them were Extended-spectrum β-lactamase (ESBL) producers. Among Salmonella (n = 3) and Campylobacter (n = 9), only one strain of C. jejuni was identified as MDR. Most of the identified serotypes/sequence types had already been found to be associated with human disease. These results show that free-living birds in Portugal may act as carriers of foodborne pathogens linked to human disease, some of them resistant to critically important antimicrobials.

Eco-epidemiological screening of multi-host wild rodent communities in the UK reveals pathogen strains of zoonotic interest

Wild rodent communities represent ideal systems to study pathogens and parasites shared among sympatric species. Such studies are useful in the investigation of eco-epidemiological dynamics, improving disease management strategies and reducing zoonotic risk. The aim of this study was to investigate pathogen and parasites shared among rodent species (multi-host community) in West Wales in an area where human/wildlife disease risk was not previously assessed. West Wales is predominantly rural, with human settlements located alongside to grazing areas and semi-natural landscapes, creating a critical human-livestock-wildlife interface. Ground-dwelling wild rodent communities in Wales were live-trapped and biological samples - faeces and ectoparasites - collected and screened for a suite of pathogens and parasites that differ in types of transmission and ecology. Faecal samples were examined to detect Herpesvirus, Escherichia coli, and Mycobacterium microti. Ticks and fleas were collected, identified to species based on morphology and genetic barcodes, and then screened for Anaplasma phagocytophilum, Babesia microti, Borrelia burgdorferi sensu lato, and Bartonella sp. All the pathogens and parasites screened pose a characteristic epidemiological challenge, such as variable level of generalism, unknown zoonotic potential, and lack of data. The results showed that the bank vole Myodes glareolus had the highest prevalence of all pathogens and parasites. Higher flea species diversity was detected than in previous studies, and at least two Bartonella species were found circulating, one of which has not previously been detected in the UK. These key findings offer new insights into the distribution of selected pathogen and parasites and subsequent zoonotic risk, and provide new baselines and perspectives for further eco-epidemiological research.

Pet birds as potential reservoirs of virulent and antibiotic resistant zoonotic bacteria

Bacterial pathogens carried by pet birds are considered a risk for birds, workers, and pet owners. This study investigated the potential of pet birds as reservoirs for virulent multidrug-resistant (MDR) zoonotic bacteria and assessed the genetic relatedness and diversity of bacterial isolates from pet birds and human contacts. Cloacal and tracheal swabs from 125 pet birds and 70 hand swabs from human contacts were collected. The results revealed that the pet birds were reservoirs for Escherichia coli, Klebsiella pneumoniae (17.6 %, each), and Staphylococcus aureus (15.2 %). These isolates were also identified in their human contacts, at percentages of 14.3 %, 12.9 %, and 24.3 %, respectively. Virulence associated genes were identified from E. coli (stx2, stx2f, eaeA, and hlyA), K. pneumoniae (fimH, TraT, and magA), and S. aureus (PVL, hly, sea, sed genes) isolates. Multidrug-resistant E. coli, K. pneumoniae, and S. aureus were highly prevalent (81.3 %, 90.3 %, and 61.1 %, respectively). The genetic relationship between the E. coli and K. pneumoniae isolates from the pet birds and human contacts were determined by ERIC-PCR, while, RAPD-PCR was used for the S. aureus isolates. ERIC-PCR was found to have the highest discriminatory power. The clustering of the isolates from the pet birds and human contacts indicated potential transmission between the birds and workers. In conclusion, pet birds could act as potential reservoirs for zoonotic bacterial pathogens; thus, posing a risk to their human contacts.

Generalizability and comparability of prevalence estimates in the wild bird literature: methodological and epidemiological considerations

Wild birds have been the focus of a great deal of research investigating the epidemiology of zoonotic bacteria and antimicrobial resistance in the environment. While enteric pathogens (e.g. Campylobacter, Salmonella, and E. coli O157:H7) and antimicrobial resistant bacteria of public health importance have been isolated from a wide variety of wild bird species, there is a considerable variation in the measured prevalence of a given microorganism from different studies. This variation may often reflect differences in certain ecological and biological factors such as feeding habits and immune status. Variation in prevalence estimates may also reflect differences in sample collection and processing methods, along with a host of epidemiological inputs related to overall study design. Because the generalizability and comparability of prevalence estimates in the wild bird literature are constrained by their methodological and epidemiological underpinnings, understanding them is crucial to the accurate interpretation of prevalence estimates. The main purpose of this review is to examine methodological and epidemiological inputs to prevalence estimates in the wild bird literature that have a major bearing on their generalizability and comparability. The inputs examined here include sample type, microbiological methods, study design, bias, sample size, definitions of prevalence outcomes and parameters, and control of clustering. The issues raised in this review suggest, among other things, that future prevalence studies of wild birds should avoid opportunistic sampling when possible, as this places significant limitations on the generalizability of prevalence data.

Are we overestimating risk of enteric pathogen spillover from wild birds to humans?

Enteric illnesses remain the second largest source of communicable diseases worldwide, and wild birds are suspected sources for human infection. This has led to efforts to reduce pathogen spillover through deterrence of wildlife and removal of wildlife habitat, particularly within farming systems, which can compromise conservation efforts and the ecosystem services wild birds provide. Further, Salmonella spp. are a significant cause of avian mortality, leading to additional conservation concerns. Despite numerous studies of enteric bacteria in wild birds and policies to discourage birds from food systems, we lack a comprehensive understanding of wild bird involvement in transmission of enteric bacteria to humans. Here, we propose a framework for understanding spillover of enteric pathogens from wild birds to humans, which includes pathogen acquisition, reservoir competence and bacterial shedding, contact with people and food, and pathogen survival in the environment. We place the literature into this framework to identify important knowledge gaps. Second, we conduct a meta‐analysis of prevalence data for three human enteric pathogens, Campylobacter spp., E. coli, and Salmonella spp., in 431 North American breeding bird species. Our literature review revealed that only 3% of studies addressed the complete system of pathogen transmission. In our meta‐analysis, we found a Campylobacter spp. prevalence of 27% across wild birds, while prevalence estimates of pathogenic E. coli (20%) and Salmonella spp. (6.4%) were lower. There was significant bias in which bird species have been tested, with most studies focusing on a small number of taxa that are common near people (e.g. European starlings Sturnus vulgaris and rock pigeons Columba livia) or commonly in contact with human waste (e.g. gulls). No pathogen prevalence data were available for 65% of North American breeding bird species, including many commonly in contact with humans (e.g. black‐billed magpie Pica hudsonia and great blue heron Ardea herodias), and our metadata suggest that some under‐studied species, taxonomic groups, and guilds may represent equivalent or greater risk to human infection than heavily studied species. We conclude that current data do not provide sufficient information to determine the likelihood of enteric pathogen spillover from wild birds to humans and thus preclude management solutions. The primary focus in the literature on pathogen prevalence likely overestimates the probability of enteric pathogen spillover from wild birds to humans because a pathogen must survive long enough at an infectious dose and be a strain that is able to colonize humans to cause infection. We propose that future research should focus on the large number of under‐studied species commonly in contact with people and food production and demonstrate shedding of bacterial strains pathogenic to humans into the environment where people may contact them. Finally, studies assessing the duration and intensity of bacterial shedding and survival of bacteria in the environment in bird faeces will help provide crucial missing information necessary to calculate spillover probability. Addressing these essential knowledge gaps will support policy to reduce enteric pathogen spillover to humans and enhance bird conservation efforts that are currently undermined by unsupported fears of pathogen spillover from wild birds.

Carriage and Subtypes of Foodborne Pathogens Identified in Wild Birds Residing near Agricultural Lands in California: a Repeated Cross-Sectional Study

The shedding dynamics of foodborne pathogens by wild birds on farmland are not well characterized. This yearlong study sampled wild birds for foodborne pathogens within agricultural lands in northern California. There was a low prevalence of Salmonella spp., Escherichia coli O157:H7, and non-O157 Shiga-toxin producing E. coli (prevalence, 0.34% to 0.50%) identified in bird populations in this study. However, pathogens of public health importance (such as Salmonella Newport, E. coli O157:H7, and STEC O103 and O26) were identified in fecal samples, and two birds carried STEC on their feet or feathers. Identical pathogen strains were shared episodically among birds and between wild geese and free-range cattle. This result suggests a common source of contamination in the environment and potential transmission between species. These findings can be used to assess the risk posed by bird intrusions in produce fields and enhance policy decisions toward the comanagement of food safety and farmland habitat conservation.

Current California agricultural practices strive to comanage food safety and habitat conservation on farmland. However, the ecology of foodborne pathogens in wild bird populations, especially those avian species residing in proximity to fresh produce production fields, is not fully understood. In this repeated cross-sectional study, avifauna within agricultural lands in California were sampled over 1 year. Feces, oral swabs, and foot/feather swabs were cultured for zoonotic Salmonella spp., Escherichia coli O157:H7, and non-O157 Shiga toxin-producing E. coli (STEC) and characterized by serotyping and pulsed-field gel electrophoresis. Of 60 avian species sampled, 8 species (13.3%, bird groups of sparrows, icterids, geese, wrens, and kinglets) were positive for at least one of these foodborne pathogens. At the individual bird level, the detection of foodborne pathogens was infrequent in feces (n = 583; 0.5% Salmonella, 0.34% E. coli O157:H7, and 0.5% non-O157 STEC) and in feet/feathers (n = 401; 0.5% non-O157 STEC), and it was absent from oral swabs (n = 353). Several subtypes of public health importance were identified, including Salmonella enterica serotype Newport, E. coli O157:H7, and STEC serogroups O103 and O26. In late summer and autumn, the same STEC subtype was episodically found in several individuals of the same and different avian species, suggesting a common source of contamination in the environment. Sympatric free-range cattle shared subtypes of STEC O26 and O163 with wild geese. A limited rate of positive detection in wild birds provides insights into broad risk profile for contamination considerations but cannot preclude or predict risk on an individual farm.

IMPORTANCE The shedding dynamics of foodborne pathogens by wild birds on farmland are not well characterized. This yearlong study sampled wild birds for foodborne pathogens within agricultural lands in northern California. There was a low prevalence of Salmonella spp., Escherichia coli O157:H7, and non-O157 Shiga-toxin producing E. coli (prevalence, 0.34% to 0.50%) identified in bird populations in this study. However, pathogens of public health importance (such as Salmonella Newport, E. coli O157:H7, and STEC O103 and O26) were identified in fecal samples, and two birds carried STEC on their feet or feathers. Identical pathogen strains were shared episodically among birds and between wild geese and free-range cattle. This result suggests a common source of contamination in the environment and potential transmission between species. These findings can be used to assess the risk posed by bird intrusions in produce fields and enhance policy decisions toward the comanagement of food safety and farmland habitat conservation.

Shiga toxin-producing Escherichia coli in wild ungulates

Shiga toxin-producing Escherichia coli (STEC) are zoonotic pathogens that live in the gastrointestinal tract of wildlife and cattle without causing disease. In humans, their colonization and infection lead to life-threatening disease. We investigated the occurrence of STEC in wild ungulates (wild boar, red deer and roe deer) inhabiting areas differently impacted by anthropogenic activities. STEC were detected in 9% (n = 6) of the samples and were recovered from the three species: 1 of wild boar, 4 of red deer and 1 of roe deer. All the isolates (n = 7) were non-O157 STEC encoding stx1 (n = 2; 29%) and/or stx2 genes (n = 6; 86%). O27:H30 was the most frequent serotype identified, followed by O146:H21 and O146:H28. Two STEC were O-untypable: ONT:H28 and ONT:H52. The phylo-groups identified were B1 (n = 3), E (n = 3) and F (n = 1). All the isolates recovered were susceptible to the different classes of antibiotics tested, although resistance genes were found in two strains. Apart from stx, all STEC encode many virulence factors (VF), particularly adhesins and/or other toxins. A strain with 13 VF collected from roe deer has a high enterohemorrhagic risk due to the presence of intimin, hemolysin and protease effectors genes. Enterohemorrhagic E. coli (EHEC) are implicated in the major cases of human infection and mortality, highlighting the zoonotic potential of wildlife-associated STEC. Wild ungulates are reservoirs of STEC potentially pathogenic to humans. Therefore, following the One Health concept, it is crucial to establish worldwide local monitoring programs that will benefit human, animal and environmental health.

Virulence traits of avian pathogenic (APEC) and fecal (AFEC) E. coli isolated from broiler chickens in Algeria

Avian pathogenic E. coli (APEC) is the etiologic agent of avian colibacillosis, the most common disease responsible for chicken morbidity in the world. Although multiple virulence-associated factors were identified, their prevalence in Algeria is still poorly known. In the present research, 92 avian pathogenic E. coli (APEC) isolates were recovered from broilers with clinical signs and lesions of colibacillosis. In addition, 32 E. coli isolates collected from feces of healthy birds (AFEC) were included for comparison. All isolates were investigated by PCR for the presence of a total of 11 virulence-associated genes described for avian pathogenic (iroN, ompT, hlyF, iss, iutA, and fimC) and diarrheagenic E. coli (eae, stx, elt/est, ipaH, and aggR). The sensitivity of 39 APEC isolates to 16 antibiotics was also determined using antimicrobial pretreated microplates. Here, we report that 98% of the examined isolates host at least one of the tested virulence factors. The most prevalent genes in APEC were iutA (90.6%), ompT (86.9%), and iss (85.8%); whereas, iutA (78.1%), fimC (78.1%), and iroN (68.7%) were the highest prevalent genes in AFEC. Our data showed that none of the AFEC isolates harbor any of the tested diarrheagenic genes. Moreover, only elt/est (5.4%), stx (2.1%), and ipaH (2.1%) genes were carried by APEC isolates. We further established that ceftazodime, ceftiofur, mequindox, amoxicillin/clavulanic acid, and meropenem were the most efficient antibiotics against the analyzed APEC isolates. Overall, our findings provide more insights about APEC and AFEC virulence potential in Algeria which could participate in the fight against colibacillosis.

Bactericidal, quorum quenching and anti-biofilm nanofactories: a new niche for nanotechnologists

Despite several conventional potent antibacterial therapies, bacterial infections pose a significant threat to human health because they are emerging as the leading cause of death worldwide. Due to the development of antibiotic resistance in bacteria, there is a pressing demand to discover novel approaches for developing more effective therapies to treat multidrug-resistant bacterial strains and biofilm-associated infections. Therefore, attention has been especially devoted to a new and emerging branch of science "nanotechnology" to design non-conventional antimicrobial chemotherapies. A range of nanomaterials and nano-sized carriers for conventional antimicrobial agents have fully justified their potential to combat bacterial diseases by reducing cell viability, by attenuating quorum sensing, and by inhibiting/or eradicating biofilms. This communication summarizes emerging nano-antimicrobial therapies in treating bacterial infections, particularly using antibacterial, quorum quenching, and anti-biofilm nanomaterials as new approaches to tackle the current challenges in combating infectious diseases.

Animal Reservoirs of Shiga Toxin-Producing Escherichia coli

Shiga toxin-producing Escherichia coli (STEC) strains have been detected in a wide diversity of mammals, birds, fish, and several insects. Carriage by most animals is asymptomatic, thus allowing for dissemination of the bacterium in the environment without detection. Replication of the organism may occur in the gastrointestinal tract of some animals, notably ruminants. Carriage may also be passive or transient, without significant amplification of bacterial numbers while in the animal host. Animals may be classified as reservoir species, spillover hosts, or dead-end hosts. This classification is based on the animal's ability to (i) transmit STEC to other animal species and (ii) maintain STEC infection in the absence of continuous exposure. Animal reservoirs are able to maintain STEC infections in the absence of continuous STEC exposure and transmit infection to other species. Spillover hosts, although capable of transmitting STEC to other animals, are unable to maintain infection in the absence of repeated exposure. The large diversity of reservoir and spillover host species and the survival of the organism in environmental niches result in complex pathways of transmission that are difficult to interrupt.

Occurrence of diarrheagenic virulence genes and genetic diversity in Escherichia coli isolates from fecal material of various avian hosts in British Columbia, Canada

Contamination of surface water by fecal microorganisms originating from human and nonhuman sources is a public health concern. In the present study, Escherichia coli isolates (n = 412) from the feces of various avian host sources were screened for various virulence genes: stx1 and stx2 (Shiga toxin-producing E. coli [STEC]), eae (enteropathogenic E. coli [EPEC]), est-h, est-p, and elt (encoding heat-stable toxin [ST] variants STh and STp and heat-labile toxin [LT], respectively) (enterotoxigenic E. coli [ETEC]), and ipaH (enteroinvasive E. coli [EIEC]). None of the isolates were found to be positive for stx1, while 23% (n = 93) were positive for only stx2, representing STEC, and 15% (n = 63) were positive for only eae, representing EPEC. In addition, five strains obtained from pheasant were positive for both stx2 and eae and were confirmed as non-O157 by using an E. coli O157 rfb (rfbO157) TaqMan assay. Isolates positive for the virulence genes associated with ETEC and EIEC were not detected in any of the hosts. The repetitive element palindromic PCR (rep-PCR) fingerprint analysis identified 143 unique fingerprints, with an overall Shannon diversity index of 2.36. Multivariate analysis of variance (MANOVA) showed that the majority of the STEC and EPEC isolates were genotypically distinct from nonpathogenic E. coli and clustered independently. MANOVA analysis also revealed spatial variation among the E. coli isolates, since the majority of the isolates clustered according to the sampling locations. Although the presence of virulence genes alone cannot be used to determine the pathogenicity of strains, results from this study show that potentially pathogenic STEC and EPEC strains can be found in some of the avian hosts studied and may contaminate surface water and potentially impact human health.

An attempt to identify the likely sources of Escherichia coli harboring toxin genes in rainwater tanks

In this study, 200 Escherichia coli isolates from 22 rainwater tank samples in Southeast Queensland, Australia were tested for the presence of 10 toxin genes (i.e., stx(1), stx(2), hlyA, ehxA, LT1, ST1, cdtB, east1, cnf1, and cvaC) associated with intestinal and extraintestinal pathotypes. Among the 22 rainwater tanks tested, 5 (28%), 7 (32%), 7 (32%), and 1 (5%) tanks contained E. coli harboring ST1, east1, cdtB, and cvaC genes, respectively. Of the 200 E. coli isolates from the 22 tanks, 43 (22%) strains from 13 (59%) tanks were harboring toxin gene. An attempt was made to establish a link between bird and possum fecal contamination and the presence of these potential clinically significant E. coli strains harboring toxin genes in rainwater tanks. Among the 214 E. coli isolates tested from birds, 30 (14%), 11 (5%) and 18 (8%) strains contained east1, cdtB, and cvaC toxin genes, respectively. Similarly, among the 214 possum E. coli isolates, 74 (35%) contained only the east1 toxin gene. All E. coli strains from rainwater tanks, bird and possum fecal samples harboring toxin genes were biochemically fingerprinted. Biochemical phenotypes (BPTs) of 14 (33%) E. coli strains from 7 rainwater tanks and 9 (21%) E. coli strains from 6 rainwater tanks were identical to a number of BPTs of E. coli strains isolated from bird and possum feces suggesting that these animals may be the sources of these E. coli in rainwater tanks. as a precautionary measure, it is recommended that rainwater should be treated prior to drinking. In addition, proper maintenance of roof and gutter hygiene and elimination of overhanging tree branches and other structures where possible to prevent the movement of possums are highly recommended.

Occurrence of intestinal and extraintestinal virulence genes in Escherichia coli isolates from rainwater tanks in Southeast Queensland, Australia

In this study, 200 Escherichia coli isolates from 22 rainwater tank samples in Southeast Queensland, Australia, were tested for the presence of 20 virulence genes (VGs) associated with intestinal and extraintestinal pathotypes. In addition, E. coli isolates were also classified into phylogenetic groups based on the detection of the chuA, yjaA, and TSPE4.C2 genes. Of the 22 rainwater tanks, 8 (36%) and 5 (23%) were positive for the eaeA (belonging to enteropathogenic E. coli [EPEC] and Shiga-toxigenic E. coli [STEC]) and ST1 (belonging to enterotoxigenic E. coli [ETEC]) genes, respectively. VGs (cdtB, cvaC, ibeA, kpsMT allele III, PAI, papAH, and traT) belonging to extraintestinal pathogenic E. coli (ExPEC) were detected in 15 (68%) of the 22 rainwater tanks. Of the 22 samples, 17 (77%) and 11 (50%) contained E. coli belonging to phylogenetic groups A and B1, respectively. Similarly, 10 (45%) and 16 (72%) contained E. coli belonging to phylogenetic groups B2 and D, respectively. Of the 96 of the 200 strains from 22 tanks that were VG positive, 40 (42%) were carrying a single VG, 36 (37.5%) were carrying two VGs, 17 (18%) were carrying three VGs, and 3 (3%) had four or more VGs. This study reports the presence of multiple VGs in E. coli strains belonging to the STEC, EPEC, ETEC, and ExPEC pathotypes in rainwater tanks. The public health risks associated with potentially clinically significant E. coli in rainwater tanks should be assessed, as the water is used for drinking and other, nonpotable purposes. It is recommended that rainwater be disinfected using effective treatment procedures such as filtration, UV disinfection, or simply boiling prior to drinking.

Shiga toxin: expression, distribution, and its role in the environment

In this review, we highlight recent work that has increased our understanding of the production and distribution of Shiga toxin in the environment. Specifically, we review studies that offer an expanded view of environmental reservoirs for Shiga toxin producing microbes in terrestrial and aquatic ecosystems. We then relate the abundance of Shiga toxin in the environment to work that demonstrates that the genetic mechanisms underlying the production of Shiga toxin genes are modified and embellished beyond the classical microbial gene regulatory paradigms in a manner that apparently "fine tunes" the trigger to modulate the amount of toxin produced. Last, we highlight several recent studies examining microbe/protist interactions that postulate an answer to the outstanding question of why microbes might harbor and express Shiga toxin genes in the environment.

Avian colibacillosis and salmonellosis: a closer look at epidemiology, pathogenesis, diagnosis, control and public health concerns

Avian colibacillosis and salmonellosis are considered to be the major bacterial diseases in the poultry industry world-wide. Colibacillosis and salmonellosis are the most common avian diseases that are communicable to humans. This article provides the vital information on the epidemiology, pathogenesis, diagnosis, control and public health concerns of avian colibacillosis and salmonellosis. A better understanding of the information addressed in this review article will assist the poultry researchers and the poultry industry in continuing to make progress in reducing and eliminating avian colibacillosis and salmonellosis from the poultry flocks, thereby reducing potential hazards to the public health posed by these bacterial diseases.