A Pilot Study on Integrating Videography and Environmental Microbial Sampling to Model Fecal Bacterial Exposures in Peri-Urban Tanzania

Diarrheal diseases are a leading cause of under-five mortality and morbidity in sub-Saharan Africa. Quantitative exposure modeling provides opportunities to investigate the relative importance of fecal-oral transmission routes (e.g. hands, water, food) responsible for diarrheal disease. Modeling, however, requires accurate descriptions of individuals' interactions with the environment (i.e., activity data). Such activity data are largely lacking for people in low-income settings. In the present study, we collected activity data and microbiological sampling data to develop a quantitative microbial exposure model for two female caretakers in peri-urban Tanzania. Activity data were combined with microbiological data of contacted surfaces and fomites (e.g. broom handle, soil, clothing) to develop example exposure profiles describing second-by-second estimates of fecal indicator bacteria (E. coli and enterococci) concentrations on the caretaker's hands. The study demonstrates the application and utility of video activity data to quantify exposure factors for people in low-income countries and apply these factors to understand fecal contamination exposure pathways. This study provides both a methodological approach for the design and implementation of larger studies, and preliminary data suggesting contacts with dirt and sand may be important mechanisms of hand contamination. Increasing the scale of activity data collection and modeling to investigate individual-level exposure profiles within target populations for specific exposure scenarios would provide opportunities to identify the relative importance of fecal-oral disease transmission routes.

Multidrug resistant pathogenic Escherichia coli status in water sources and Yamuna River in and around Mathura, India

The present study was taken to understand the status of water resources in the holy city of Mathura, India. As it is a tourist place and pilgrims come from all around the world, there are more chances of spread of pathogens through them. The pathogens which are particularly excreted through urine and feces are most commonly excreted out. E. coli is one of them which causes many severe diseases particularly in neonatal calves or neonates of human. As the city has its limitation of accommodation and river Yamuna is also shrinking, the pressure of millions of pilgrims has enormous, drastic and stipulated effect on water resources particularly river Yamuna. The samples collected showed the presence of pathogenic E. coli. Out of total 100 samples 40 were found positive for E. coli. The 60 samples of different water resources showed the presence of E. coli in 26 samples while 14 were found positive out of 40 samples of Yamuna water. The total coliforms count ranged between 1.08 log10 CFU m L(-1) to 6.34 log10 CFU m L(-1) in drinking water sources and waste water, respectively. The high percentage of positive samples and coliforms count may be because of the method and place of sample collection. When these isolates were analyzed for antibiotic sensitivity pattern against some commonly used antibiotics. They showed a variable effectiveness against them. The number of resistant isolate is significant enough to make an alert at the earliest to protect the water resources and also to secure better and brighter future of human population.

Characterization of enteropathogenic and Shiga toxin-producing Escherichia coli in cattle and deer in a shared agroecosystem

Shiga toxin-producing Escherichia coli (STEC) is an important foodborne pathogen. Cattle are suggested to be an important reservoir for STEC; however, these pathogens have also been isolated from other livestock and wildlife. In this study we sought to investigate transmission of STEC, enterohemorrhagic E. coli (EHEC) and enteropathogenic E. coli (EPEC) between cattle and white-tailed deer in a shared agroecosystem. Cattle feces were collected from 100 animals in a Michigan dairy farm in July 2012, while 163 deer fecal samples were collected during two sampling periods (March and June). The locations of deer fecal pellets were recorded via geographic information system mapping and microsatellite multi-locus genotyping was used to link the fecal samples to individual deer at both time points. Following subculture to sorbitol MacConkey agar and STEC CHROMagar, the pathogens were characterized by serotyping, stx profiling, and PCR-based fingerprinting; multilocus sequence typing (MLST) was performed on a subset. STEC and EHEC were cultured from 12 to 16% of cattle, respectively, and EPEC was found in 36%. Deer were significantly less likely to have a pathogen in March vs. June where the frequency of STEC, EHEC, and EPEC was 1, 6, and 22%, respectively. PCR fingerprinting and MLST clustered the cattle- and deer-derived strains together in a phylogenetic tree. Two STEC strains recovered from both animal species shared MLST and fingerprinting profiles, thereby providing evidence of interspecies transmission and highlighting the importance of wildlife species in pathogen shedding dynamics and persistence in the environment and cattle herds.

Effect of proximity to a cattle feedlot on Escherichia coli O157:H7 contamination of leafy greens and evaluation of the potential for airborne transmission

The impact of proximity to a beef cattle feedlot on Escherichia coli O157:H7 contamination of leafy greens was examined. In each of 2 years, leafy greens were planted in nine plots located 60, 120, and 180 m from a cattle feedlot (3 plots at each distance). Leafy greens (270) and feedlot manure samples (100) were collected six different times from June to September in each year. Both E. coli O157:H7 and total E. coli bacteria were recovered from leafy greens at all plot distances. E. coli O157:H7 was recovered from 3.5% of leafy green samples per plot at 60 m, which was higher (P < 0.05) than the 1.8% of positive samples per plot at 180 m, indicating a decrease in contamination as distance from the feedlot was increased. Although E. coli O157:H7 was not recovered from air samples at any distance, total E. coli was recovered from air samples at the feedlot edge and all plot distances, indicating that airborne transport of the pathogen can occur. Results suggest that risk for airborne transport of E. coli O157:H7 from cattle production is increased when cattle pen surfaces are very dry and when this situation is combined with cattle management or cattle behaviors that generate airborne dust. Current leafy green field distance guidelines of 120 m (400 feet) may not be adequate to limit the transmission of E. coli O157:H7 to produce crops planted near concentrated animal feeding operations. Additional research is needed to determine safe set-back distances between cattle feedlots and crop production that will reduce fresh produce contamination.

[BACTERIAL FACTORS AND INTRAUTERINE INFECTION OF THE NEWBORN]

The role and value of the bacterial factor in development pre-natal infection of newborns is studied. It is considered microflora of patrimonial ways of pregnant women, as basic pathogenesis factor of an ascending way infection of newborns. On an example of the spent bacteriological researches correlation communication between microflora of patrimonial ways, placenta and an ascending way infection of newborns is shown.

Transmission of antibiotic-resistant Escherichia coli between cattle, humans and the environment in peri-urban livestock keeping communities in Morogoro, Tanzania

Urban and peri-urban livestock farming is expanding world-widely because of increased urbanization and demands for food of animal origin. Such farming practices pose a public health risk as livestock are reservoirs of several zoonotic pathogens. In an attempt to determine the fecal transmission between livestock and people, 100 household clusters keeping cattle in close proximity of humans were selected in urban and peri-urban areas of Morogoro in Tanzania. One hundred eighteen ampicillin and tetracycline resistant Escherichia coli (40 from human stool, 50 from cattle feces, 21 from soil and seven from water samples) were isolated from 44 different clusters. Pulsed-field gel electrophoresis (PFGE) of XbaI digested chromosomal DNA was used to compare the genetic relatedness of the ampicillin- and tetracycline-resistant E. coli isolates. Indistinguishable PFGE band patterns of the ampicillin- and tetracycline-resistant E. coli isolates were found in samples from 23 (52%) clusters. This suggests that transfer of fecal microorganisms between cattle, humans, water and soils within the farms and from livestock farms to the neighborhood occurred commonly. Logistic regression showed that animal housing infrastructures (Odd Ratio=11.2, 95% CI=1.1-119.3) were associated with E. coli showing identical PFGE types within and between clusters. There is a need to improve animal husbandry and manure management practices to reduce risks of transmission of enteropathogens between livestock and humans in urban and peri-urban farming.

Geographic divergence of bovine and human Shiga toxin–producing Escherichia coli O157:H7 genotypes, New Zealand

Shiga toxin-producing Escherichia coli (STEC)O157:H7 is a zoonotic pathogen of public health concern worldwide. To compare the local and large-scale geographic distributions of genotypes of STEC O157:H7 isolates obtained from various bovine and human sources during 2008–2011, we used pulsed-field gel electrophoresis and Shiga toxin–encoding bacteriophage insertion (SBI) typing. Using multivariate methods, we compared isolates from the North and South Islands of New Zealand with isolates from Australia and the United States. The STEC O157:H7 population structure differed substantially between the 2 islands and showed evidence of finer scale spatial structuring, which is consistent with highly localized transmission rather than disseminated foodborne outbreaks. The distribution of SBI types differed markedly among isolates from New Zealand, Australia, and the United States. Our findings also provide evidence for the historic introduction into New Zealand of a subset of globally circulating STEC O157:H7 strains that have continued to evolve and be transmitted locally between cattle and humans.

ESBL-producing Escherichia coli isolated from bloodstream infections--antimicrobial susceptibility, conjugative transfer of resistance genes and phylogenetic origin

BACKGROUND

The prevalence of bloodstream infections (BSIs) due to ESBL-producing Escherichia coli (ESBL-EC) strains has increased dramatically over the past years.

OBJECTIVES

Characterization of ESBL-EC isolates collected from BSIs with regard to their antimicrobial susceptibility and phylogenetic background. The conjugative transfer of resistance determinants to the E. coli reference strain K12 C600 was also investigated.

MATERIAL AND METHODS

A collection of forty-eight ESBL-EC strains recovered from BSIs was subjected to the study. These strains were obtained from the ICU (intensive care unit) of the Medical University Hospital, Wrocław, Poland, during a four-year period (2009-2012). All the isolates were screened for ESBL production by the double disk synergy test (DDST). Transferability of plasmid-mediated resistance genes was performed by the conjugational broth method. Susceptibility to antibiotics and chemotherapeutics of clinical isolates and transconjugants was determined by the agar dilution method. PCR assay was used to detect the blaCTX-M gene in ESBL-EC tested and transconjugants. Affiliation to phylogenetic groups was done by the triplex PCR method.

RESULTS

Conjugational transfer of plasmids responsible for ESBL to a recipient strain was successful for all the ESBL-EC analyzed (donors). The conjugation frequencies ranging from 2.3×10(-7) to 5.2×10(-1) per donor. In vitro susceptibility testing revealed that all the ESBL-EC isolates and their transconjugants were resistant to most of the antimicrobial agents tested with the exception of carbapenems, tigecycline, and β-lactam-clavulanate combinations. Moreover, all the donor strains and their transconjugants were found to contain the blaCTX-M gene. The majority of the isolates analyzed belonged to phylogroups B2 (62.5%) and D (25%), whereas groups B1 and A were less frequently represented (8.3% and 4.2%, respectively).

CONCLUSIONS

The results of the study confirm the need of antibiotic policies and effective infection control measures in hospital settings to minimize BSIs caused by multi-resistant ESBL-producing pathogens.

[Estimation of the transfer of ESBL-producing Escherichia coli to humans in Germany]

In 2011 EFSA has evaluated the risk for the consumer caused by ESBL-/AmpC-producing bacteria in food of animal origin and in livestock animals. Human-to-human transfer in hospitals.and in the community was considered as the most relevant route of transmission for ESBL-producing E. coli. ESBL-/AmpC-producing E. coli are in Germany, as in many other Member States of the European Union, widely spread in food of animal origin and in livestock animals. In an assessment of the relevance of livestock animals as reservoir for ESBL-/AmpC-producing E. coli as well as for ESBL-coding resistance genes the heterogeneity of the resistance genes, plasmids and bacteria in animals, foods and humans needs to be considered. In this context, both, the clonal spread of bacteria as well as horizontal transfer of resistance genes, e. g. by plasmids, have to be analyzed. Whereas studies in The Netherlands identified poultry as the most relevant reservoir, the transfer of ESBL-gene carrying plasmids from pigs to the farmers was demonstrated in Denmark. First attempts to quantify the relevance of livestock animals as reservoir for ESBL-producing E. coli in Germany showed, that the proportions of the most frequent ESBL-resistance genes are quite different between animal and human derived E. coli isolates. If in addition properties of the bacterial cells, e.g. resistance to several antibiotic classes are considered, only a small proportion of human isolates showed the same patterns as animal isolates. The results achieved so far demonstrate that certain ESBL-types are prevalent in all livestock populations investigated. Currently, the majority of cases of colonizations with ESBL-producing E. coli among humans cannot be directly linked to livestock and food-producing animals as reservoirs. This reflects that transmission routes are more complex and other reservoirs and sources including human-human interactions have to be taken into consideration.

[Postdonation information: the French fourth hemovigilance sub-process]

Postdonation information is the knowledge of information about the donor or his donation, occurring after it, which challenges quality or safety of the blood products stemming from this or other donations. Classical hemovigilance sub-processes concerning donors or recipients adverse events do not cover this topic. France is just about to make it official as a fourth sub-process. Less formal management of postdonation information is already set up for more than ten years. French data of the year 2013 are presented, including the regional notification level and the national reporting one. A significant level of heterogeneity is observed as for other hemovigilance sub-processes. It is mainly due to subjective rather than objective differences in risk appreciation. A real consensual work is expected about it in the future.

Spatial epidemiology of Escherichia coli O157:H7 in dairy cattle in relation to night roosts Of Sturnus vulgaris (European Starling) in Ohio, USA (2007-2009)

The goal of our study was to use spatial scan statics to determine whether the night roosts of European starlings (Sturnus vulgaris) act as point sources for the dissemination of Escherichia coli O157:H7 among dairy farms. From 2007 to 2009, we collected bovine faecal samples (n = 9000) and starling gastrointestinal contents (n = 430) from 150 dairy farms in northeastern Ohio, USA. Isolates of E. coli O157:H7 recovered from these samples were subtyped using multilocus variable-number tandem repeat analysis (MLVA). Generated MLVA types were used to construct a dendrogram based on a categorical multistate coefficient and unweighted pair-group method with arithmetic mean (UPGMA). Using a focused spatial scan statistic, we identified statistically significant spatial clusters among dairy farms surrounding starling night roosts, with an increased prevalence of E. coli O157:H7-positive bovine faecal pats, increased diversity of distinguishable MLVA types and a greater number of isolates with MLVA types from bovine-starling clades versus bovine-only clades. Thus, our findings are compatible with the hypothesis that starlings have a role in the dissemination of E. coli O157:H7 among dairy farms, and further research into starling management is warranted.

Epidemiology of extended-spectrum β-lactamase producing Escherichia coli in the stools of returning Japanese travelers, and the risk factors for colonization

OBJECTIVE

Travel overseas has recently been considered a risk factor for colonization with drug-resistant bacteria. The purpose of this study was to establish the epidemiology and risk factors associated with the acquisition of drug-resistant bacteria by Japanese travelers.

METHODS

Between October 2011 and September 2012, we screened the stools of 68 Japanese returning travelers for extended-spectrum β-lactamase (ESBL) producing Escherichia coli. All specimens were sampled for clinical reasons. Based on the results, the participants were divided into an ESBL-producing E. coli positive group (18 cases; 26%) and an ESBL-producing E. coli negative group (50 cases; 74%), and a case-control study was performed. Microbiological analyses of ESBL-producing strains, including susceptibility tests, screening tests for metallo-β-lactamase, polymerase chain reaction amplification and sequencing of blaCTX-M genes, multilocus sequence typing, and whole genome sequencing, were also conducted.

RESULTS

In a univariate comparison, travel to India was a risk factor (Odds Ratio 13.6, 95% Confidence Interval 3.0-75.0, p<0.0001). There were no statistical differences in the characteristics of the travel, such as backpacking, purpose of travel, interval between travel return and sampling stool, and duration of travel. Although 10 of 13 analyzed strains (77%) produced CTX-M-15, no ST131 clone was detected.

CONCLUSION

We must be aware of the possibilities of acquiring ESBL-producing E. coli during travel in order to prevent the spread of these bacteria not only in Japan but globally.

Shiga toxin-producing Escherichia coli distribution and characterization in a pasture-based cow-calf production system

Shiga toxin-producing Escherichia coli (STEC) strains are commonly found in cattle gastrointestinal tracts. In this study, prevalence and distribution of E. coli virulence genes (stx1, stx2, hlyA, and eaeA) were assessed in a cow-calf pasture-based production system. Angus cows (n = 90) and their calves (n = 90) were kept in three on-farm locations, and fecal samples were collected at three consecutive times (July, August, and September 2011). After enrichment of samples, stx1, stx2, eaeA, and hlyA were amplified and detected with a multiplex PCR (mPCR) assay. Fecal samples positive for stx genes were obtained from 93.3% (84 of 90) of dams and 95.6% (86 of 90) of calves at one or more sampling times. Age class (dam or calf), spatial distribution of cattle (farm locations B, H, K), and sampling time influenced prevalence and distribution of virulence genes in the herd. From 293 stx-positive fecal samples, 744 E. coli colonies were isolated. Virulence patterns of isolates were determined through mPCR assay: stx1 was present in 41.9% (312 of 744) of the isolates, stx2 in 6.5% (48 of 744), eaeA in 4.2% (31 of 744), and hlyA in 2.4% (18 of 744). Prevalence of non-O157 STEC was high among the isolates: 33.8% (112 of 331) were STEC O121, 3.6% (12 of 331) were STEC O103, and 1.8% (6 of 331) were STEC O113. One isolate (0.3%) was identified as STEC O157. Repetitive element sequence-based PCR (rep-PCR) fingerprinting was used to study genetic diversity of stx-positive E. coli isolates. Overall, rep-PCR fingerprints were highly similar, supporting the hypothesis that strains are transmitted between animals but not necessarily from a dam to its calf. Highly similar STEC isolates were obtained at each sampling time, but isolates obtained from dams were more diverse than those from calves, suggesting that strain differences in transference may exist. Understanding the transfer of E. coli from environmental and animal sources to calves may aid in developing intervention strategies to reduce E. coli colonization of young cattle.

The influence of social structure, habitat, and host traits on the transmission of Escherichia coli in wild elephants

Social structure is proposed to influence the transmission of both directly and environmentally transmitted infectious agents. However in natural populations, many other factors also influence transmission, including variation in individual susceptibility and aspects of the environment that promote or inhibit exposure to infection. We used a population genetic approach to investigate the effects of social structure, environment, and host traits on the transmission of Escherichia coli infecting two populations of wild elephants: one in Amboseli National Park and another in Samburu National Reserve, Kenya. If E. coli transmission is strongly influenced by elephant social structure, E. coli infecting elephants from the same social group should be genetically more similar than E. coli sampled from members of different social groups. However, we found no support for this prediction. Instead, E. coli was panmictic across social groups, and transmission patterns were largely dominated by habitat and host traits. For instance, habitat overlap between elephant social groups predicted E. coli genetic similarity, but only in the relatively drier habitat of Samburu, and not in Amboseli, where the habitat contains large, permanent swamps. In terms of host traits, adult males were infected with more diverse haplotypes, and males were slightly more likely to harbor strains with higher pathogenic potential, as compared to adult females. In addition, elephants from similar birth cohorts were infected with genetically more similar E. coli than elephants more disparate in age. This age-structured transmission may be driven by temporal shifts in genetic structure of E. coli in the environment and the effects of age on bacterial colonization. Together, our results support the idea that, in elephants, social structure often will not exhibit strong effects on the transmission of generalist, fecal-oral transmitted bacteria. We discuss our results in the context of social, environmental, and host-related factors that influence transmission patterns.

Small distances can keep bacteria at bay for days

Transmission of pathogens between spatially separated hosts, i.e., indirect transmission, is a commonly encountered phenomenon important for epidemic pathogen spread. The routes of indirect transmission often remain untraced, making it difficult to develop control strategies. Here we used a tailor-made design to study indirect transmission experimentally, using two different zoonotic bacteria in broilers. Previous experiments using a single bacterial species yielded a delay in the onset of transmission, which we hypothesized to result from the interplay between diffusive motion of infectious material and decay of infectivity in the environment. Indeed, a mathematical model of diffusive pathogen transfer predicts a delay in transmission that depends both on the distance between hosts and on the magnitude of the pathogen decay rate. Our experiments, carried out with two bacterial species with very different decay rates in the environment, confirm the difference in transmission delay predicted by the model. These results imply that for control of an infectious agent, the time between the distant exposure and the infection event is important. To illustrate how this can work we analyzed data observed on the spread of vancomycin-resistant Enterococcus in an intensive care unit. Indeed, a delayed vancomycin-resistant Enterococcus transmission component was identified in these data, and this component disappeared in a study period in which the environment was thoroughly cleaned. Therefore, we suggest that the impact of control strategies against indirect transmission can be assessed using our model by estimating the control measures' effects on the diffusion coefficient and the pathogen decay rate.

Low compliance with national guidelines for preventing transmission of group 1 nationally notifiable infectious diseases in Korea

PURPOSE

This study was performed to evaluate the compliance with, and adequacy of, the Korean national guidelines which had been recommended until 2011 for isolation of patients with group 1 nationally notifiable infectious diseases (NNIDs), namely cholera, typhoid fever, paratyphoid fever, shigellosis, and enterohemorrhagic Escherichia coli (EHEC) infection.

MATERIALS AND METHODS

We evaluated the clinical and microbiological characteristics of confirmed cases of group 1 NNIDs and compliance with the guidelines in 20 Korean hospitals nationwide in 2000-2010. We also compared the Korean guidelines with international guidelines.

RESULTS

Among 528 confirmed cases (8 cases of cholera, 232 of typhoid fever, 81 of paratyphoid fever, 175 of shigellosis, and 32 EHEC infections), strict compliance with the Korean guideline was achieved in only 2.6% to 50.0%, depending on the disease. While the Korean guidelines recommend isolation of all patients with group 1 NNIDs, international guidelines recommend selective patient isolation and screening for fecal shedding, depending on the type of disease and patient status.

CONCLUSION

Compliance with the previous national guidelines for group 1 NNIDs in Korea was generally very low. Further studies are needed to evaluate whether compliance was improved after implementation of the new guideline in 2012.

Molecular characterization of integrons in clinical isolates of betalactamase-producing Escherichia coli and Klebsiella pneumoniae in Iran

Integrons are considered to play a significant role in the evolution and spread of antibiotic resistance genes. A total of 349 clinical isolates of Escherichia coli and Klebsiella pneumoniae were investigated for molecular characterization of integrons and betalactamases. Antimicrobial susceptibility testing was also performed as the Clinical and Laboratory Standards Institute (CLSI) guidelines. The frequency of extended spectrum betalactamases (ESBL) or metallo-betalactamases (MBL)-producing isolates, patient demographics, and the susceptibility to various antimicrobial agents were described. BlaCTX-M was the most frequently detected betalactamase in all isolates. Moreover, MBL producing K. pneumoniae carried blaIMP and blaVIM at 100 and 41·6%, respectively but no MBL-positive E. coli was detected. Class 1 integrons were more frequent among E. coli and K. pneumoniae isolates in comparison with class 2 integrons and the frequency of intI2 in K. pneumoniae was significantly higher than E. coli isolates. Five different resistance gene arrays were identified among class 1 integrons. Dihydrofolate reductase (dfrA) and aminoglycoside adenyltransferase (aad) gene cassettes were found to be predominant in the class 1 integrons. These results indicate that class 1 integrons are widespread among ESBL-producing isolates of K. pneumoniae and E. coli and appropriate surveillance and control measures are essential to prevent further dissemination of these elements among Enterobacteriaceae in our country.

Duration of shedding of Verocytotoxin-producing Escherichia coli in children and risk of transmission in childcare facilities in England

Exclusion of children with presumptive Verocytotoxin-producing Escherichia coli (VTEC) from childcare facilities until negative stool specimens are obtained is routine practice that disrupts families. We estimated the shedding and exclusion duration and transmission risk in such facilities. The study population comprised 225 children aged <6 years attending 201 childcare facilities in England with microbiologically confirmed VTEC in 2010-2011. We estimated the interval from onset to first negative specimen, and identified transmission events with secondary cases linked to facilities. The median duration of shedding was 31 days, and median period of exclusion was 39·5 days. Cases attending facilities while shedding VTEC did so for a median of 2 days before exclusion. Secondary cases occurred in 6/83 facilities (7%) attended by infectious cases. Despite evidence of VTEC shedding at facilities, transmission is relatively low. Revised control guidelines could consider supervised return for prolonged asymptomatic shedders.

Unusual coliranuloma in very young Japanese quail chick

A commercial Japanese Quail farmer reported death from 8 to 30% in three different flocks of 3 days old age, 3 weeks old age and 4 weeks old age of total flock size 18800. Investigation was under taken to find out the cause of death. Post mortem examination followed by bacteriological, virological and histopathological examinations revealed spontaneous colibacillosis. E. coli serotypes O24, O6 and O128 were isolated in pure culture. Isolates were strong congo red binder and sensitive to enterofloxain, gentamicin and chloramphenicol. Pathological lesions also correlated well with the infection of E. coli. Involvement of potentially zoonotic, E. coli serotype O6 in causing coligranuloma and death in 3 days old Japanese quail establishes its virulence character in Japanese quails. Strict biosecurity measures were advised to prevent transmission of public health importance E. coli serotype O6 from infected Japanese quails to humans.

Wild ungulates as disseminators of Shiga toxin-producing Escherichia coli in urban areas

Background

In 2008, children playing on a soccer field in Colorado were sickened with a strain of Shiga toxin-producing Escherichia coli (STEC) O157:H7, which was ultimately linked to feces from wild Rocky Mountain elk. We addressed whether wild cervids were a potential source of STEC infections in humans and whether STEC was ubiquitous throughout wild cervid populations in Colorado.

Methodology/Principal Findings

We collected 483 fecal samples from Rocky Mountain elk and mule deer in urban and non-urban areas. Samples testing positive for STEC were higher in urban (11.0%) than non-urban (1.6%) areas. Elk fecal samples in urban areas had a much higher probability of containing STEC, which increased in both urban and non-urban areas as maximum daily temperature increased. Of the STEC-positive samples, 25% contained stx1 strains, 34.3% contained stx2, and 13% contained both stx1 and stx2. Additionally, eaeA genes were detected in 54.1% of the positive samples. Serotypes O103, and O146 were found in elk and deer feces, which also have the potential to cause human illness.

Conclusions/Significance

The high incidence of stx2 strains combined with eaeA and E-hyl genes that we found in wild cervid feces is associated with severe human disease, such as hemolytic uremic syndrome. This is of concern because there is a very close physical interface between elk and humans in urban areas that we sampled. In addition, we found a strong relationship between ambient temperature and incidence of STEC in elk feces, suggesting a higher incidence of STEC in elk feces in public areas on warmer days, which in turn may increase the likelihood that people will come in contact with infected feces. These concerns also have implications to other urban areas where high densities of coexisting wild cervids and humans interact on a regular basis.

[Prevalence and transmission of plasmid-mediated quinolone resistance qnrS gene among Escherichia coli isolates in a poultry farm]

OBJECTIVE

To investigate the prevalence and transmission of plasmid-mediated quinolone resistance qnrS gene among Escherichia coli isolates in a poultry farm and its environment.

METHODS

E. coli isolates from fecal samples in a poultry farm and its environment from February to June 2010 were screened for the prevalence and dynamic changes of qnrS gene. Susceptibility testing, conjugant experiments, and pulsed field gel electrophoresis of qnrS-positive isolates were also performed.

RESULTS

A total of 379 isolates were randomly obtained from feces samples of chickens, ducks and geese in a poultry farm and its environment. The qnrS positive strains were detected in all sources of isolates and two alleles of qnrS were prevalent on this farm. The positive rate of qnrS gene in environmental strains was 29.2%, which was significantly higher than that in the avian strains (13.4%). Chicken can quickly acquire qnrS gene after they live on this farm. Transconjugants of the qnrS gene can elevate ciprofloxacin Minimun inhibitory concentrations (MICs) by 16 - 32 fold compared with the recipient. Various determinants for resistance to other antimicrobial agents were also transferred with the qnrS plasmid. The Xba I PFGE analysis of the qnrS positive strains showed that the dissemination of qnrS was not mainly due to the clonal dissemination of positive strains. However, qnrS-positive strains with indistinguishable PFGE patterns were found in ducks and environment.

CONCLUSION

Both horizontal gene transfer and clonal spread could be responsible for the dissemination of the qnrS gene in the poultry farm and its environment, but it is mainly disseminated by horizontal transmission.

Recent advances in understanding enteric pathogenic Escherichia coli

Although Escherichia coli can be an innocuous resident of the gastrointestinal tract, it also has the pathogenic capacity to cause significant diarrheal and extraintestinal diseases. Pathogenic variants of E. coli (pathovars or pathotypes) cause much morbidity and mortality worldwide. Consequently, pathogenic E. coli is widely studied in humans, animals, food, and the environment. While there are many common features that these pathotypes employ to colonize the intestinal mucosa and cause disease, the course, onset, and complications vary significantly. Outbreaks are common in developed and developing countries, and they sometimes have fatal consequences. Many of these pathotypes are a major public health concern as they have low infectious doses and are transmitted through ubiquitous mediums, including food and water. The seriousness of pathogenic E. coli is exemplified by dedicated national and international surveillance programs that monitor and track outbreaks; unfortunately, this surveillance is often lacking in developing countries. While not all pathotypes carry the same public health profile, they all carry an enormous potential to cause disease and continue to present challenges to human health. This comprehensive review highlights recent advances in our understanding of the intestinal pathotypes of E. coli.

Risk of acquiring extended-spectrum β-lactamase-producing Klebsiella species and Escherichia coli from prior room occupants in the intensive care unit

OBJECTIVE. To quantify the association between admission to an intensive care unit (ICU) room most recently occupied by a patient positive for extended-spectrum β-lactamase (EBSL)-producing gram-negative bacteria and acquisition of infection or colonization with that pathogen. DESIGN. Retrospective cohort study. SETTING AND PATIENTS. The study included patients admitted to medical and surgical ICUs of an academic medical center between September 1, 2001, and June 30, 2009. METHODS. Perianal surveillance cultures were obtained at admission to the ICU, weekly, and at discharge from the ICU. Patients were included if they had culture results that were negative for ESBL-producing gram-negative bacteria at ICU admission and had an ICU length of stay longer than 48 hours. Pulsed-field gel electrophoresis (PFGE) was performed on ESBL-positive isolates from patients who acquired the same bacterial species (eg, Klebsiella species or Escherichia coli) as the previous room occupant. RESULTS. Among 9,371 eligible admissions (7,651 unique patients), 267 (3%) involved patients who acquired an ESBL-producing pathogen in the ICU; of these patients, 32 (12%) were hospitalized in a room in which the prior occupant had been positive for ESBL. Logistic regression results suggested that the prior occupant's ESBL status was not significantly associated with acquisition of an ESBL-producing pathogen (adjusted odds ratio, 1.39 [95% confidence interval, 0.94-2.08]) after adjusting for colonization pressure and antibiotic exposure in the ICU. PFGE results suggested that 6 (18%) of 32 patients acquired a bacterial strain that was the same as or closely related to the strain obtained from the prior occupant. CONCLUSIONs. These data suggest that environmental contamination may not play a substantial role in the transmission of ESBL-producing pathogens among ICU patients. Intensifying environmental decontamination may be less effective than other interventions in preventing transmission of ESBL-producing pathogens.

Hands and water as vectors of diarrheal pathogens in Bagamoyo, Tanzania

Diarrheal disease is a leading cause of under-five childhood mortality worldwide, with at least half of these deaths occurring in sub-Saharan Africa. Transmission of diarrheal pathogens occurs through several exposure routes including drinking water and hands, but the relative importance of each route is not well understood. Using molecular methods, this study examines the relative importance of different exposure routes by measuring enteric bacteria (pathogenic Escherichia coli) and viruses (rotavirus, enterovirus, adenovirus) in hand rinses, stored water, and source waters in Bagamoyo, Tanzania. Viruses were most frequently found on hands, suggesting that hands are important vectors for viral illness. The occurrence of E. coli virulence genes (ECVG) was equivalent across all sample types, indicating that both water and hands are important for bacterial pathogen transmission. Fecal indicator bacteria and turbidity were good predictors of ECVG, whereas turbidity and human-specific Bacteroidales were good predictors of viruses. ECVG were more likely found in unimproved water sources, but both ECVG and viral genes were detected in improved water sources. ECVG were more likely found in stored water of households with unimproved sanitation facilities. The results provide insights into the distribution of pathogens in Tanzanian households and offer evidence that hand-washing and improved water management practices could alleviate viral and bacterial diarrhea.

Defining relatedness in studies of transmission of antimicrobial-resistant organisms: variability in definitions across studies and impact of different approaches on study conclusions

OBJECTIVE

Comparison of studies evaluating patient-to-patient transmission of organisms is difficult, given the lack of standardized criteria. We used fluoroquinolone-resistant Escherichia coli (FQREC) as a model to characterize variability in definitions of relatedness across studies and to evaluate the resultant impact on study conclusions.

DESIGN

Narrative review and cohort study.

METHODS

The narrative review compared relatedness criteria across studies of FQREC. Additionally, an existing database was used to compare relatedness of isolates on the basis of molecular criteria alone versus molecular plus clinical criteria with different temporal cutoffs (hospitalization overlap of ≥1 day or allowance for nonoverlap of hospitalization dates of ≤7 days or ≤30 days).

RESULTS

Forty-six articles met narrative review inclusion criteria. Sixteen studies exclusively utilized molecular criteria to define relatedness. Thirty studies included molecular and clinical criteria. Of these, 6 included temporal data (ie, time period of isolate identification), 10 included patient location, and 14 included proximity and temporal criteria. For the database analysis, 353 patients were colonized with FQREC. There were 2 main clusters containing 48 and 17 related isolates within 49 pulsed-field gel electrophoresis types. Among the clusters, 18.4% of isolates were related by molecular criteria. Incorporating clinical criteria, fewer isolates were considered related: 5.7% of isolates using 30-day criteria, 3.1% using 7-day criteria, and 1.4% using 1-day overlap.

CONCLUSIONS

There is considerable variability in definitions of relatedness of FQREC. Utilizing molecular criteria alone to define relatedness overestimates transmission compared with definitions including clinical criteria. Standard definitions of relatedness in studies of antimicrobial-resistant organisms are needed.