Prevalence of diarrheagenic Escherichia coli in finns with or without diarrhea during a round-the-world trip

Prevalence and virulence potential of Aeromonas spp. isolated from human diarrheal samples in North East Italy

IMPORTANCE

In this work, we demonstrate the epidemiologic relevance of the Aeromonas genus as the cause of infective diarrhea in North East Italy, both in children and adult subjects, with the significative presence of highly pathogenic strains. Aeromonas strains possess a heterogeneous armamentarium of pathogenicity factors that allows the microbe to affect a wide range of human intestinal epithelial cell processes that justify the ability to induce diarrhea through different mechanisms and cause diseases of variable severity, as observed for other gastrointestinal pathogens. However, it remains to be determined whether specific genotype(s) are associated with clinical pictures of different severity to implement the diagnostic and therapeutic approaches for this relevant enteric pathogen.

Frequency of five Escherichia Coli pathotypes in Iranian adults and children with acute diarrhea

Background

Knowledge about the distribution of Escherichia Coli (E. coli) pathotypes in Iran is limited. This nation-wide survey aims to provide a comprehensive description of the distribution of five pathogenic E. coli in Iran.

Methods

Stool samples were collected from 1,306 acute diarrhea cases from 15 provinces (2013–2014). E. coli-positive cultures underwent PCR testing for the detection of STEC, ETEC, EPEC, EAEC, and EIEC pathotypes. Pathotype frequency by province, age-group, and season was estimated.

Results

979 diarrhea samples (75.0%) were culture-positive for E. coli (95% CI: 72.6, 77.3%), and 659 (50.5%) were pathogenic E. coli (95% CI: 47.8, 53.2%). STEC was the most frequent pathotype (35.4%). ETEC (14.0%) and EPEC (13.1%) were the second and the third most frequent pathotypes, respectively. EAEC (4.3%) and EIEC (0.3%) were not highly prevalent. Fars (88.7%) and Khorasan-e-Razavi (34.8%) provinces had the highest and lowest frequencies, respectively. E. coli pathotypes were more frequent in warmer than cooler seasons, showed the highest frequency among children under five years of age (73%), and had no significant association with participants’ gender.

Conclusions

Diarrheagenic E. coli may be an important cause of acute diarrhea in adults and children in Iran. STEC and ETEC seem to be widespread in the country with a peak in warmer seasons, impacting the recommended use of seasonal STEC and ETEC vaccines, especially in high-risk groups. Monitoring the incidence of E. coli pathotypes, serotypes, and antibiotic resistance over time is highly recommended for evaluation of interventions.

Bacterial, viral and parasitic pathogens analysed by qPCR: Findings from a prospective study of travellers' diarrhoea

BACKGROUND

The diagnostics of travellers' diarrhoea (TD) has been revolutionised by multiplex qPCR assays. While mostly of bacterial aetiology, viruses and parasites account for the disease among 10-20% of travellers. Despite this, prospective studies applying qPCR assays remain scarce that cover not only bacteria, such as the various diarrhoeagenic Escherichia coli (DEC), but also viral and parasitic pathogens.

METHOD

We analysed by qPCR pre- and post-travel stool samples of 146 Finnish travellers for bacterial, viral and parasitic pathogens: enteropathogenic (EPEC), enteroaggregative (EAEC), enterotoxigenic (ETEC), enterohaemorrhagic (EHEC), and enteroinvasive (EIEC) E. coli; Shigella, Campylobacter, Salmonella, Yersinia and Vibrio cholerae; norovirus G1 and G2, rotavirus, enteroviruses, and sapovirus; and Giardia lamblia, Entamoeba histolytica, and Cryptosporidium. Symptoms and medication data during travel were collected by questionnaires.

RESULTS

We detected bacterial pathogens in 102/146 samples (69.9%; EAEC, EPEC, ETEC most common), viral ones in 13 (8.9%; norovirus most common), and parasitic ones in one (0.7%; Giardia). Noroviruses were associated with severe symptoms (23.5% versus non-severe 4.9%). In the TD group, 41.7% (5/12) of those with viral pathogens (vs. 13.3%; 11/83 without) took antibiotics.

CONCLUSION

Viral pathogens, particularly noroviruses, prevail in severe TD. The symptoms of viral disease are often severe and lead to unwarranted use of antibiotics.

DETECTION OF DIARRHEAGENIC ESCHERICHIA COLI IN HUMAN DIARRHEIC STOOL AND DRINKING WATER SAMPLES IN OUAGADOUGOU, BURKINA FASO

Background:

The presence of diarrheagenic Escherichia coli (DEC) in drinking water, is a grave public health problem. This study was aimed at characterization of diarrheagenic Escherichia coli isolated from drinking water and faecal samples from diarrheic patients in Ouagadougou, Burkina Faso.

Materials and Methods:

A total of 242 water samples consisting of 182 potable sachets and 60 from boreholes were collected in the period between October 2018 and April 2019 in the city of Ouagadougou. Faecal samples were also collected from 201 diarrheic patients visiting National Public Health Laboratory for a biological diagnosis by coproculture. The presence of virulence genes associated with DEC was determined by 16-plex polymerase chain reaction from bacteria culture.

Results:

From drinking water, we found 17% (42/242) Escherichia coli isolates in which 1% (2/242) DEC were detected. Among analyzed samples (182 sachet water versus 60 borehole water), the two DEC (01 ETEC and 01 EPEC) were detected in sachet water. DEC were detected in 20% (40/201) of patients. Enteroaggregative Escherichia coli (EAEC) were mostly detected in 10% followed by Enteropathogenic Escherichia coli (EPEC) in 4%, Enteroinvasive Escherichia coli (EIEC) in 2%, and Shiga toxin-producing Escherichia coli (STEC) 0.5%. However, Enterotoxigenic Escherichia coli (ETEC) was not detected alone, but in co-infections with EAEC.

Conclusion:

The present study documented the prevalence of Escherichia coli pathovars associated in patients with diarrhea, and shows that drinking water might be a source of DEC transmission in human.

Risk factors for different intestinal pathogens among patients with traveler's diarrhea: A retrospective analysis at a German travel clinic (2009-2017)

BACKGROUND

Travelers' diarrhea (TD) is the most common illness experienced by travelers to developing regions of the world and may be caused by bacterial, parasitic or viral pathogens. The available diagnostic tests include stool microscopy for parasitic infections, culture-dependent methods for bacterial infections and molecular methods for bacterial, parasitic and viral infections.

METHOD

We retrospectively evaluated demographic, clinical and microbiological data of patients presenting with TD at our travel clinic between 2009 and 2017.

RESULTS

Among 676 patients with TD included in our study, at least one etiologic agent was found in 21% (n = 145) of cases. In total, 195 enteropathogens were detected of which 110 were bacteria, 70 protozoa and 15 helminths. Bacterial infections were significantly more common when symptoms were present less than 14 days and travel duration did not exceed 29 days. Protozoa and helminths were predominantly detected in patients with longer lasting complaints. After stool culture was replaced by a multiplex-PCR gastrointestinal pathogen panel (GPP) at our center, significantly more intestinal bacterial pathogens were detected.

CONCLUSIONS

Our results support an individualized approach in the diagnostic workup of patients with TD taking host and travel characteristics into account to avoid unnecessary diagnostic testing. Molecular culture-independent diagnostic stool tests provide better coverage of the variety of etiological agents than traditional stool culture and have the benefit of rapid detection. However, the high sensitivity bears challenges differentiating colonization from infection.

Enteric etiological surveillance in acute diarrhea stool of United States Military Personnel on deployment in Thailand, 2013-2017

Background

Diarrhea remains a major public health problem for both civilian and military populations. This study describes the prevalence of acute diarrheal illness etiological agents, their antibiotic resistance distribution patterns, the resulting impact upon military force health protection, and potential prevention and treatment strategies.

Results

Forty-eight acute diarrhea stool samples from US military personnel deployed to Thailand from 2013–2017 were screened for enteric pathogens using ELISA, the TaqMan Array Card (TAC), and conventional microbiological methods. These isolates were also evaluated using antimicrobial susceptibility testing (AST) against ampicillin (AMP), azithromycin (AZM), ceftriaxone (CRO), ciprofloxacin (CIP), nalidixic acid (NA), erythromycin (ERY), and trimethoprim-sulfamethoxazole (SXT) using commercial methodology. Susceptibility results were interpreted following the CLSI and NARM guidelines. Questionnaire data obtained from 47/48 volunteers indicated that 89.4% (42/47) reported eating local food and the most common clinical symptoms were nausea and abdominal pain (51%; 24/47). Multiple bacterial species were identified from the 48 stool samples with diarrhea etiological agents being detected in 79% (38/48) of the samples distributed as follows: 43.8% (21/48) Campylobacter jejuni and Campylobacter species, 42% (20/48) diarrheagenic Escherichia coli, and 23% (11/48) Salmonella. Co-infections were detected in 46% (22/48) of the samples. All C. jejuni isolates were resistant to CIP and NA. One C. jejuni isolate exhibited resistance to both AZM and ERY. Lastly, an association between exposure to poultry and subsequent detection of the diarrhea-associated pathogens E. coli and P. shigelloides was significant (p < 0.05).

Conclusion

The detection of Campylobacter isolates with CIP, AZM and ERY resistance has critical force health protection and public health implications, as these data should guide effective Campylobacteriosis treatment options for deployed military members and travelers to Southeast Asia. Additional research efforts are recommended to determine the association of pathogen co-infections and/or other contributing factors towards diarrheal disease in military and traveler populations. Ongoing surveillance and AST profiling of potential disease-causing bacteria is required for effective disease prevention efforts and treatment strategies.

Safety of ready-to-eat chicken in Burkina Faso: Microbiological quality, antibiotic resistance, and virulence genes in Escherichia coli isolated from chicken samples of Ouagadougou

In Burkina Faso, flamed/grilled chickens are very popular and well known to consumers. The aim of this study was to evaluate the microbiological quality, the antibiotic resistance, and the virulence gene from Escherichia coli isolated from these chickens in Ouagadougou. A total of 102 grilled, flamed, and fumed chickens were collected in Ouagadougou and analyzed, using standard microbiological methods. All E. coli isolates were checked with the antimicrobial test and also typed by 16‐plex PCR. The mean of aerobic mesophilic bacteria (AMB) and thermo‐tolerant coliforms (TTC) was found respectively between 6.90 ± 0.12 × 10⁷CFU/g to 2.76 ± 0.44 × 10⁸CFU/g and 2.4 ± 0.82 × 10⁷CFU/g to 1.27 ± 0.9 × 10⁸CFU/g. E. coli strains were found to 27.45%. Forty samples (38.24%) were unacceptable based on the AMB load. Fifty‐nine samples (57.85%) were contaminated with TTCs. Low resistance was observed with antibiotics of betalactamin family. Diarrheagenic E. coli strains were detected in 21.43% of all samples. This study showed that flamed/grilled chickens sold in Ouagadougou could pose health risks for the consumers. Need of hygienic practices or system and good manufacturing practices is necessary to improve the hygienic quality of flamed/grilled chickens. Our results highlight the need of control of good hygiene and production practices to contribute to the improvement of the safety of the products and also to avoid antibiotic resistance. Slaughter, scalding, evisceration, plucking, bleeding, washing, rinsing, preserving, grilling, and selling may be the ways of contamination.

Travellers' diarrhoea: Impact of TD definition and control group design on study results

BACKGROUND

Travellers' diarrhoea (TD) is a common health problem among visitors to the (sub)tropics. Much research deals with aetiology, prevention, and post-infection sequalae, yet the data may not allow comparisons due to incompatible definitions of TD and No TD control groups.

METHOD

The impact of defining TD and No TD control groups was explored by revisiting our recent data. We set up two TD groups: classical TD i.e. ≥3 loose or liquid stools/day and WHO TD (diarrhoea as defined by the WHO) i.e. any diarrhoea, and four No TD groups by TD definition and timing (no classical/WHO TD during travel, no ongoing classical/WHO TD).

RESULTS

TD was recorded for 37% versus 65% of subjects when using classical versus WHO definitions, respectively; the proportions of the various pathogens proved similar. The strictest criterion for the No TD control group (no WHO TD during travel) yielded pathogens among 61% and the least strict (no ongoing classical TD) among 73% of the travellers; the differences were greatest for enteroaggregative Escherichia coli and Campylobacter.

CONCLUSIONS

Definition of TD and control group design substantially impact on TD study results. The WHO definition yields more cases, but the pathogen selection is similar by both definitions. Design of the No TD control group was found critical: only those remaining asymptomatic throughout the journey should be included.

Characterization of Diarrheagenic Escherichia coli Isolated in Organic Waste Products (Cattle Fecal Matter, Manure and, Slurry) from Cattle's Markets in Ouagadougou, Burkina Faso

Cattle farming can promote diarrheal disease transmission through waste, effluents or cattle fecal matter. The study aims to characterize the diarrheagenic Escherichia coli (DEC) isolated from cattle feces, manure in the composting process and slurry, collected from four cattle markets in Ouagadougou. A total of 585 samples (340 cattle feces, 200 slurries and 45 manures in the composting process) were collected from the four cattle markets between May 2015 and May 2016. A multiplex Polymerase Chain Reaction (PCR), namely 16-plex PCR, was used to screen simultaneously the virulence genes specific for shiga toxin-producing E. coli (STEC), enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC), enteroinvasive E. coli (EIEC) and enteroaggregative E. coli (EAEC). DEC was detected in 10.76% of samples. ETEC was the most prevalent (9.91%). STEC and EAEC have been observed with the same rate (0.51%). ETEC were detected in 12.64% of cattle feces, in 6.66% of manure in the composting process and in 5% of slurry. STEC were detected in 0.58% of cattle feces and in 2.22% of manure in the composting process. EAEC was detected only in 1% of slurry and in 2.22% of manure in the composting process. ETEC strains were identified based on estIa gene and/or estIb gene and/or elt gene amplification. Of the 58 ETEC, 10.34% contained astA, 17.24% contained elt, 3.44% contained estIa and 79.31% contained estIb. The two positive EAEC strains contained only the aggR gene, and the third was positive only for the pic gene. The results show that effluent from cattle markets could contribute to the spreading of DEC in the environment in Burkina Faso.

Prospective study of pathogens in asymptomatic travellers and those with diarrhoea: aetiological agents revisited

Travellers' diarrhoea (TD) remains the most frequent health problem encountered by visitors to the (sub)tropics. Traditional stool culture identifies the pathogen in only 15% of cases. Exploiting PCR-based methods, we investigated TD pathogens with a focus on asymptomatic travellers and severity of symptoms. Pre- and post-travel stools of 382 travellers with no history of antibiotic use during travel were analysed with a multiplex quantitative PCR for Salmonella, Yersinia, Campylobacter, Shigella, Vibrio cholerae and five diarrhoeagenic Escherichia coli: enteroaggregative (EAEC), enteropathogenic (EPEC), enterotoxigenic (ETEC), enterohaemorrhagic (EHEC) and enteroinvasive (EIEC). The participants were categorized by presence/absence of TD during travel and on return, and by severity of symptoms. A pathogen was indentified in 61% of the asymptomatic travellers, 83% of those with resolved TD, and 83% of those with ongoing TD; 25%, 43% and 53% had multiple pathogens, respectively. EPEC, EAEC, ETEC and Campylobacter associated especially with ongoing TD symptoms. EAEC and EPEC proved more common than ETEC. To conclude, modern methodology challenges our perception of stool pathogens: all pathogens were common both in asymptomatic and symptomatic travellers. TD has a multibacterial nature, but diarrhoeal symptoms mostly associate with EAEC, EPEC, ETEC and Campylobacter.

Occurrence of virulence gene signatures associated with diarrhoeagenic and non-diarrhoeagenic pathovars of Escherichia coli isolates from some selected rivers in South-Western Nigeria

BACKGROUND

Diarrhoeal diseases are attributable to unsafe water stemming from improper sanitation and hygiene and are reportedly responsible for extensive morbidity and mortality particularly among children in developed and developing countries.

METHODS

Water samples from selected rivers in Osun State, South-Western Nigeria were collected and analyzed using standard procedures. Escherichia coli isolates (n=300) were screened for 10 virulence genes using polymerase chain reaction for pathotyping.

RESULTS

While the virulence gene (VG) lt for enterotoxigenic E. coli had the highest prevalence of 45%, the enteropathogenic E. coli genes eae and bfp were detected in 6 and 4% of the isolates respectively. The VGs stx1 and stx2 specific for the enterohemorrhagic E. coli pathotypes were detected in 7 and 1% of the isolates respectively. Also, the VG eagg harboured by enteroaggregative pathotype and diffusely-adherent E. coli VG daaE were detected in 2 and 4% of the isolates respectively and enteroinvasive E. coli VG ipaH was not detected. In addition, the VGs papC for uropathogenic and ibeA for neonatal meningitis were frequently detected in 19 and 3% of isolates respectively.

CONCLUSIONS

These findings reveal the presence of diarrhoeagenic and non-diarrhoeagenic E. coli in the selected rivers and a potential public health risk as the rivers are important resources for domestic, recreational and livelihood usage by their host communities.

Diverse and abundant multi-drug resistant E. coli in Matang mangrove estuaries, Malaysia

E.coli, an important vector distributing antimicrobial resistance in the environment, was found to be multi-drug resistant, abundant, and genetically diverse in the Matang mangrove estuaries, Malaysia. One-third (34%) of the estuarine E. coli was multi-drug resistant. The highest antibiotic resistance prevalence was observed for aminoglycosides (83%) and beta-lactams (37%). Phylogenetic groups A and B1, being the most predominant E. coli, demonstrated the highest antibiotic resistant level and prevalence of integrons (integron I, 21%; integron II, 3%). Detection of phylogenetic group B23 downstream of fishing villages indicates human fecal contamination as a source of E. coli pollution. Enteroaggregative E. coli (1%) were also detected immediately downstream of the fishing village. The results indicated multi-drug resistance among E. coli circulating in Matang estuaries, which could be reflective of anthropogenic activities and aggravated by bacterial and antibiotic discharges from village lack of a sewerage system, aquaculture farms and upstream animal husbandry.

Characterization of Diarrheagenic Antimicrobial Resistant Escherichia coli Isolated From Pediatric Patients in Tehran, Iran

Background:

Acute infectious diarrhea is one of the most important causes of morbidity and mortality worldwide.

Objectives:

The objective of this study was to characterize antimicrobial resistant diarrheagenic Escherichia coli strains isolated from diarrheic children in Tehran, IR Iran.

Patients and Methods:

In total, 550 stool samples from diarrheic pediatric patients, aged less than 60 months, were collected and immediately transferred to the laboratory. Isolation and identification of E. coli strains was done using bacteriological methods. Antimicrobial susceptibility testing was performed using the disk diffusion technique. Multiplex PCR was used to detect aadA1, tetA, tetB, dfrA1, qnr, aac (3)-IV, sul1, blaSHV, CITM, cat1, and cmlA antibiotic resistance genes.

Results:

From the total of 550 fecal samples examined, 154 samples (28%) were positive for diarraheagenic E. coli. High rates of antibiotic resistance were seen against penicillin ﴾100%), ampicillin ﴾89.6%﴿ and tetracycline ﴾83.1%﴿. Resistance against ciprofloxacin was low ﴾28.6%﴿. The prevalence of different resistance genes in the studied strains varied from 96.10% for aadA1 gene to 40.25% for sul1 gene. The frequencies of aadA1, tetA, tetB, dfrA1, qnr, aac(3)-IV, sul1, blaSHV, CITM, cat1, and cmlA genes were 96.10%, 85.06%, 84.41%, 51.94%, 72.07%, 54.54%, 40.25%, 57.79%, 90.25%, 59.74% and 60.38%, respectively.

Conclusions:

Our results indicated that antibiotic resistance is increasing in diarraheagenic E. coli strains in Iran. It is imperative to develop strategies for prevention and control of resistant organisms. Changes in patterns of resistance against commonly used antibiotics in Iran indicate that an applied surveillance system and introduction of guidelines for appropriate antibiotic prescription are necessary.

High number of diarrhoeal co-infections in travellers to Benin, West Africa

Background

Travellers’ diarrhoea (TD) is the most frequent health problem among travellers to the tropics. Using routine techniques, the aetiology mostly remains unresolved, whereas modern molecular methods enable reducing the number of equivocal cases considerably. While many studies address the aetiology of TD in Asian, Central American and North African tourist resorts, only few focus on Western Africa.

Methods

Stool samples from 45 travellers travelling in Benin, West Africa, were analyzed by a new multiplex qPCR assay for Salmonella, Yersinia, Campylobacter, Vibrio cholerae, Shigella or enteroinvasive (EIEC), enterohaemorrhagic (EHEC), enterotoxigenic (ETEC), enteroaggregative (EAEC), and enteropathogenic Escherichia coli (EPEC).

Results

All 18 pre-travel samples proved negative for bacterial pathogens. Of the 39/45 (87%) travellers having had TD, EPEC was detected in post-travel samples in 30 (77%) cases, EAEC in 23 (59%), ETEC in 22 (56%), Shigella or EIEC in 7 (18%), EHEC in two (5%), and Salmonella in one (3%). In 31(79%) of the TD cases two or more bacterial pathogens were identified. Two (8%) samples remained negative: both patients had taken antimicrobials for TD.

Conclusions

EPEC, EAEC and ETEC were the most common findings. 79% of the cases had a co-infection. As modern diagnostics reveals in most patients a multitude of pathogens, the role of each pathogen should be re-evaluated.

Epidemiology and genetic diversity of human astrovirus infection among hospitalized patients with acute diarrhea in Bangladesh from 2010 to 2012

BACKGROUND

Globally, human astroviruses (HAstVs) have emerged as another common cause of non-bacterial acute gastroenteritis. Limited data exist on the epidemiology and genetic diversity of HAstVs in Bangladesh.

OBJECTIVE

We describe the epidemiology of HAstV-associated diarrhea among hospitalized patients, including HAstV genotypes, clinical symptoms and co-infecting pathogens.

STUDY DESIGN

Stool samples were collected from an ongoing diarrhea etiology surveillance during 2010-2012. HAstV was detected using RT-PCR and positive samples were subsequently tested for other common viral and bacterial pathogens. Phylogenetic analysis was performed and genotyped HAstV sequences were compared with previously reported Bangladeshi HAstV strains.

RESULTS

Of 826 fecal specimens, HAstV was detected in 26 cases (3.1%) and the majority of these cases (92%) was observed in children under 3 years of age. For 6 out of the 26 cases (23%) no other co-infecting pathogens were observed, whereas for the 20 remaining cases (77%) a variety of other known enteric viral and bacterial pathogens were observed. Based on the overlap region between ORF1b (RdRp) and ORF2 (capsid), five different genotypes (HAstV-1, -2, -3, -5 and -6) were identified circulating during the study period, with HAstV-1 being the predominant type. Genetic analysis revealed that HAstV-1 strains detected in this study were distantly related (<90% similarity of the capsid protein on the nt level) with HAstV-1 strains previously reported from Bangladesh.

CONCLUSION

Our study provides an epidemiological overview and genetic diversity of HAstVs associated with acute diarrhea in Bangladesh.

A quantitative polymerase chain reaction assay for rapid detection of 9 pathogens directly from stools of travelers with diarrhea

BACKGROUND & AIMS

Every year, 80 million tourists traveling to tropical and subtropical areas contract traveler's diarrhea (TD). Forty percent to 80% of cases are caused by bacteria, yet clinical diagnostic tests are available to identify only a few of the strains that cause TD. We aimed to develop a quantitative polymerase chain reaction (qPCR) assay to identify all major pathogens in stool samples.

METHODS

We developed a low-cost, high-throughput, multiplex qPCR assay for simultaneous detection of 9 bacterial pathogens in stool samples: Salmonella, Yersinia, Campylobacter, and Vibrio cholerae, as well as Shigella or enteroinvasive Escherichia coli, enterohemorrhagic E coli, enterotoxigenic E coli (ETEC), enteroaggregative E coli (EAEC), and enteropathogenic E coli (EPEC). The assay was validated using positive (n = 245) and negative (n = 243) control strains, as well as preselected positive and negative stool samples. In addition, stool samples were collected from 96 returning travelers with TD. The findings were compared with those from routine diagnostic tests.

RESULTS

The assay detected the bacterial strains with 100% sensitivity and specificity, compared with results from the reference tests. Of all stool samples collected from travelers with TD, EPEC was found in 47%, EAEC in 46%, ETEC in 22%, enterohemorrhagic E coli in 7%, Campylobacter in 6%, Shigella or enteroinvasive E coli in 2%, and Salmonella in 2%. Multiple pathogens were found in 37% of all samples.

CONCLUSIONS

We developed a low-cost, high-throughput qPCR assay for use in routine diagnostic analysis and research. It detects the pathogenic bacteria most commonly associated with TD in stool samples with 100% sensitivity and specificity, compared with reference methods. The assay requires 4 hours, whereas current detection methods require 1 to 7 days. At least 1 TD pathogen was identified in stool samples from 76% of returning travelers, whereas conventional methods found a pathogen in only 17%. The most commonly detected bacteria were EPEC, EAEC, and ETEC.

Molecular epidemiology ofEscherichia colidiarrhoea in children in Tehran

From July to December 2003, four categories of diarrhoeagenic Escherichia coli were investigated in Tehranian children with acute diarrhoea. Stool specimens of children under 5 years of age with diarrhoea (n=200) and matched controls (n=200) without diarrhoea were studied for the presence of entero-aggregative (EAEC), enteropathogenic (EPEC), enterotoxigenic (ETEC) and Shiga toxin-producing (STEC) E. coli by PCR identification of six different genes of diarrhoeagenic E. coli. STEC isolates were typed by O157 and H7 antisera. EAEC was the most prevalent category and was found in 24% of patients with diarrhoea and 8% of controls (p<0.0001). ETEC was isolated in 15.5% of patients with diarrhoea but not in any controls ( p<0.0001), STEC in 15% of patients and 2% of controls (p<0.0001) and EPEC in 6% of patients and 5% of controls. Of 30 STEC isolates from patients with diarrhoea, seven were O157:H7 and 23 were non-O157:H7.

Bacterial and viral etiology of childhood diarrhea in Ouagadougou, Burkina Faso

BACKGROUND

Diarrhea is the most frequent health problem among children in developing countries. This study investigated the bacterial and viral etiology and related clinical and epidemiological factors in children with acute diarrhea in Ouagadougou, Burkina Faso.

METHODS

Stool specimens were collected from 283 children under 5 years of age visiting hospital due to acute diarrhea and from 60 healthy controls of similar age. Pathogens were investigated by using conventional culture techniques, PCR and immunochromatographic testing. Salmonella and Shigella strains were serotyped and their susceptibility to 23 antimicrobial agents was determined by the agar dilution method.

RESULTS

At least one pathogen was detected in 64% of the 283 patients and in 8% of the 60 controls (p < 0.001). Rotavirus was found in 30% of the patients, followed by diarrheagenic Escherichia coli (24%), Salmonella enterica ssp. enterica (9%), Shigella spp. (6%), adenovirus (5%) and Campylobacter spp. (2%). Multiple pathogens were found in 11% of the patients and in 2% of the controls (p = 0.028). Viruses were found mainly in children of ≤ 2 years of age, whereas bacteria were equally prevalent among all the age groups. Viral infections occurred mostly during the cool dry season and the bacterial infections during the rainy season. Fever (64%) and vomiting (61%) were the most common symptoms associated with diarrhea. Only one Salmonella strain was resistant to nalidixic acid and ciprofloxacin. Of the Shigella strains, one was resistant to nalidixic acid but 81% to trimethoprim- sulfamethoxazole, 63% to streptomycin and 50% to ampicillin. Most of all the other Salmonella and Shigella strains were sensitive to all antimicrobials tested.

CONCLUSION

Rotaviruses and diarrheal E. coli were the most predominant pathogens associated with acute diarrhea in Burkinabe children. Constant antimicrobial surveillance is warranted to observe for the emergence of enteric bacteria resistant to antimicrobials that are important in treatment also of severe infections.

Shiga toxin-producing Escherichia coli serotype O78:H(-) in family, Finland, 2009

STEC carrying stx_1c and hlyA genes can invade the human bloodstream.

Shiga toxin–producing Escherichia coli (STEC) is a pathogen that causes gastroenteritis and bloody diarrhea but can lead to severe disease, such as hemolytic uremic syndrome (HUS). STEC serotype O78:H^– is rare among humans, and infections are often asymptomatic. We detected a sorbitol-fermenting STEC O78:H^–stx_1c:hlyA in blood and fecal samples of a 2-week-old boy who had bacteremia and HUS and in fecal samples of his asymptomatic family members. The phenotypic and genotypic characteristics and the virulence properties of this invasive STEC were investigated. Our findings demonstrate that contrary to earlier suggestions, STEC under certain conditions can invade the human bloodstream. Moreover, this study highlights the need to implement appropriate diagnostic methods for identifying the whole spectrum of STEC strains associated with HUS.

Prevalence of diarrheagenic Escherichia coli virulence genes in the feces of slaughtered cattle, chickens, and pigs in Burkina Faso

We investigated the prevalence of the virulence genes specific for five major pathogroups of diarrheagenic Escherichia coli (DEC) in primary cultures from feces of animals slaughtered for human consumption in Burkina Faso. For the study, 704 feces samples were collected from cattle (n = 304), chickens (n = 350), and pigs (n = 50) during carcass processing. The presence of the virulence-associated genes in the mixed bacterial cultures was assessed using 16-plex polymerase chain reaction (PCR). Virulence genes indicating presence of DEC were detected in 48% of the cattle, 48% of the chicken, and 68% of the pig feces samples. Virulence genes specific for different DECs were detected in the following percentages of the cattle, chicken, and pig feces samples: Shiga toxin-producing E. coli (STEC) in 37%, 6%, and 30%; enteropathogenic E. coli (EPEC) in 8%, 37%, and 32%; enterotoxigenic E. coli (ETEC) in 4%, 5%, and 18%; and enteroaggregative E. coli (EAEC) in 7%, 6%, and 32%. Enteroinvasive E. coli (EIEC) virulence genes were detected in 1% of chicken feces samples only. The study was the first of its kind in Burkina Faso and revealed the common occurrence of the diarrheal virulence genes in feces of food animals. This indicates that food animals are reservoirs of DEC that may contaminate meat because of the defective slaughter and storage conditions and pose a health risk to the consumers in Burkina Faso.

Culture-independent real-time PCR reveals extensive polymicrobial infections in hospitalized diarrhoea cases in Kolkata, India

Culture-independent identification of diarrhoeal aetiological agents was performed using DNA harvested from diarrhoeal stool specimens with SYBR-Green-based real-time PCR targeting Vibrio cholerae, Vibrio parahaemolyticus, Campylobacter spp., Shigella spp. and three different pathotypes of diarrhoeagenic Escherichia coli. Conventional culture-dependent methods detected bacterial enteropathogens in 68 of 122 diarrhoeal stool specimens. Of 68 specimens, 59 (86.8%) had a single pathogen and the remaining nine (13.2%) had polymicrobial infections with multiple pathogens. Re-analysis of the 68 specimens by culture-independent real-time PCR methods showed that 25 (36.8%) specimens contained single pathogen and 43 (63.2%) specimens contained mixed infections with multiple pathogens. The prevalence of such high levels of polymicrobial infections would not have been detected without using real-time PCR. Culture-dependent analysis assigned 54 of the 122 selected archived specimens as 'no known aetiology'. However, re-analysis of these samples by real-time PCR showed the presence of single or multiple pathogens among 34 (63%) of these specimens. Estimation of relative pathogen load by real-time PCR in the stool specimens indicated that the inability of conventional culture-dependent methods to detect the pathogens was related to lower colony-forming units of the pathogen, as reflected by lower C(t) values. Detection of high levels of polymicrobial infection by real-time PCR indicates that in the settings like Kolkata and its surroundings, where cholera and other enteric diseases are endemic, the concept of one pathogen one disease might need to be re-evaluated.

Diarrheagenic Escherichia coli detected by 16-plex PCR in raw meat and beef intestines sold at local markets in Ouagadougou, Burkina Faso

The study investigated the prevalence of five major Escherichia coli pathogroups in raw meats and beef intestines sold at the local markets in Ouagadougou, Burkina Faso. One hundred and twenty samples (36 beef, 36 beef intestine, 24 mutton and 24 chicken samples) were purchased from four markets between October 2008 and February 2009. Fifteen virulence genes specific for Shiga toxin-producing E. coli (STEC), enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC), enteroinvasive E. coli (EIEC) and enteroaggregative E. coli (EAEC) were examined using 16-plex PCR for mixed bacterial cultures derived from the samples. One or more diarrheagenic E. coli pathogroup was detected in 51 (43%) of all the 120 samples: in 16 (44%) beef, 19 (53%) beef intestine, 9 (38%) mutton and in 7 (29%) chicken samples. Thirty three (28%) samples were positive for stx(1) and/or stx(2) indicating presence of STEC. EPEC virulence markers (eae, escV and/or ent and/or bfp and/or EHEC-hlyA) were detected in 14 (12%) stx-negative samples. ETEC virulence markers (elt and/or estIb and/or estIa) were detected in 10 (8%) samples and EAEC virulence markers (pic or aggR) in 5 (4%) samples. No EIEC was detected. The results show that in Burkina Faso the microbiological quality of retail meat is alarmingly poor due to the common occurrence of diarrheagenic E. coli bacteria.

Diarrhoeagenic Escherichia coli detected by 16-plex PCR in children with and without diarrhoea in Burkina Faso

The importance of diarrhoeagenic Escherichia coli (DEC) in Africa is poorly understood, and is unknown in Burkina Faso. This study investigated the occurrence of five major DEC pathogroups in primary cultures of stool samples from 658 Burkinabe children under 5 years old using 16-plex PCR for virulence-associated genes. At least one DEC pathogroup was detected in 45% of 471 children with diarrhoea and in 29% of 187 children without diarrhoea (p <0.001). More than one DEC pathogroup was detected in 11% of children with and 1% of children without diarrhoea (p <0.001). Enteroaggregative E. coli was the most common pathogroup in both children with diarrhoea (26%) and children without diarrhoea (21%). Enteropathogenic E. coli and enterotoxigenic E. coli were detected significantly more often in children with diarrhoea (16% and 13%) than in children without diarrhoea (5% and 4%; p <0.001 for both pathogroups). Shiga toxin-producing E. coli and enteroinvasive E. coli were detected only in children with diarrhoea (2% and 1%, respectively). Diarrhoeagenic E. coli, especially enteropathogenic and enterotoxigenic, may be important, unrecognized causes of childhood diarrhoea in Burkina Faso.

Prevalence and antimicrobial resistance of diarrheagenic Escherichia coli and Shigella species associated with acute diarrhea in Tehran, Iran

A study was performed to determine the prevalence and antimicrobial resistance of Shigella species and diarrheagenic Escherichia coli isolates cultured from patients with acute diarrhea in Tehran, Iran. Between May 2003 and May 2005, 1120 diarrheal specimens were collected and assayed for bacterial enteropathogens by conventional and molecular methods. Etiological agents were isolated from 564 (50.3%) specimens, and included 305 (54%) E coli, 157 (27.8%) Shigella species, and 102 (18%) from other genera of bacteria. The predominant E coli was Shiga toxin-producing E coli (105 isolates [34.5%]) and the predominant Shigella serotype was Shigella sonnei (88 isolates [56.1%]). A high rate of antibiotic resistance was observed among E coli, with 40 of 53 (75.5%) Shiga toxin-producing E coli isolates resistant to amoxicillin and tetra-cycline, and eight (5.2%) E coli isolates resistant to more than six antibiotics. Most Shigella isolates were resistant to tetracycline (95%) and trimethoprim-sulfamethoxazole (91.7%), with greatest antibiotic resistance observed among S sonnei (53 of 88 [60.2%] isolates). Antibiotic resistance is widespread in diarrheagenic E coli and Shigella in children with acute diarrhea in Tehran, Iran; hence, updated strategies for appropriate use of antimicrobial agents in Iran are needed.

Prevalence of diarrhoeagenic Escherichia coli in children from León, Nicaragua

Diarrhoeal disease is a public health problem worldwide, mostly affecting children in developing countries. In Nicaragua, diarrhoea is the second greatest cause of infant mortality. During the period March 2005 to September 2006, a total of 526 faecal samples from children aged 0-60 months (381 with and 145 without diarrhoea) from León, Nicaragua, were studied. In order to detect five different diarrhoeagenic Escherichia coli pathotypes simultaneously [enterotoxigenic E. coli (ETEC), enteroaggregative E. coli (EAEC), enteropathogenic E. coli (EPEC), enterohaemorrhagic E. coli (EHEC) and enteroinvasive E. coli (EIEC)], a mixture of eight primer pairs was used in a single PCR. At least one diarrhoeagenic E. coli pathotype was detected in 205 samples (53.8%) of the diarrhoea group and in 77 samples (53.1%) in the non-diarrhoea group. ETEC was detected significantly more often in children with diarrhoea (20.5%) than in children without diarrhoea (8.3%) (P=0.001). Atypical EPEC, EIEC and EAEC were detected with slightly lower frequencies in children with (16.0, 0.8 and 27.8%, respectively) than in children without (20.7, 1.4 and 33.1%, respectively) diarrhoea. EHEC was only detected in children with diarrhoea (2.1%). In conclusion, ETEC continues to be an important agent associated with diarrhoea in children from León, Nicaragua. Although not very frequent, the only findings that were 100% associated with diarrhoea were ETEC estA (4.7%) and EHEC (2.1%). Nevertheless, EAEC and EPEC were also frequent pathotypes in the population under study. In children with severe diarrhoea, more than half had EAEC, ETEC or EPEC, and EAEC was the most prevalent pathotype.

High incidence of enteroaggregative Escherichia coli among food handlers in three areas of Kenya: a possible transmission route of travelers' diarrhea

BACKGROUND

Contaminated food and water are acknowledged vehicles for the transmission of travelers' diarrhea (TD). Importance of food handlers as reservoirs of enteroaggregative Escherichia coli (EAEC), enteropathogenic E coli (EPEC), and Shiga toxin-producing E coli (STEC) causing TD has not been clearly demonstrated.

METHODS

We undertook a 1-year prospective study to determine the presence and selected risk factors of carriage of EAEC, EPEC, and STEC by 1,399 food handlers working in tourist hotels in three popular tourist destinations of Kenya. Enterotoxigenic E coli (ETEC) was not sought in this study.

RESULTS

During the period April 2003 to May 2004, EAEC harboring the aggR gene were detected from 29 (2.1%) subjects and EPEC harboring the eaeA gene and STEC harboring the stx2 gene were detected from 11 (0.8%) and 2 (0.1%) of the study subjects, respectively. Mean age of subjects with EAEC was significantly lower (24.6 y) than the rest of the study population (28.2 y) (p < 0.05). Pit latrines usage was significantly associated with the isolation of EAEC (<0.001) but not with EPEC and STEC. Four of the 29 EAEC isolates were sensitive to all antibiotics tested, and 19 (65.5%) were multidrug resistant (MDR). Antibiotic resistance varied from 6.9% for cefuroxime to 72.4% for co-trimoxazole. Six EPEC isolates (6/13, 46.2%) showed multidrug resistance. Cluster analysis of the pulsed-field gel electrophoresis (PFGE) profiles showed that the EAEC isolates belonged to two clonally unrelated genotypes.

CONCLUSIONS

We conclude that food handlers working in tourist hotels are important carriers of EAEC that could cause TD and a high proportion of the EAEC are MDR. The isolation of MDR EAEC from food handlers working in tourist hotels is of potential public health importance. There is a need for a study employing molecular methods including PFGE to examine carriage of similar pathogens in food handlers, processed foods, and travelers consuming the food who develop diarrhea.

Mutual enhancement of virulence by enterotoxigenic and enteropathogenic Escherichia coli

Enterotoxigenic Escherichia coli (ETEC) and enteropathogenic E. coli (EPEC) are common causes of diarrhea in children in developing countries. Dual infections with both pathogens have been noted fairly frequently in studies of diarrhea around the world. In previous laboratory work, we noted that cholera toxin and forskolin markedly potentiated EPEC-induced ATP release from the host cell, and this potentiated release was found to be mediated by the cystic fibrosis transmembrane conductance regulator. In this study, we examined whether the ETEC heat-labile toxin (LT) or the heat-stable toxin (STa, also known as ST) potentiated EPEC-induced ATP release. We found that crude ETEC culture filtrates, as well as purified ETEC toxins, did potentiate EPEC-induced ATP release in cultured T84 cells. Coinfection of T84 cells with live ETEC plus EPEC bacteria also resulted in enhanced ATP release compared to EPEC alone. In Ussing chamber studies of chloride secretion, adenine nucleotides released from the host by EPEC also significantly enhanced the chloride secretory responses that were triggered by crude ETEC filtrates, purified STa, and the peptide hormone guanylin. In addition, adenosine and LT had additive or synergistic effects in inducing vacuole formation in T84 cells. Therefore, ETEC toxins and EPEC-induced damage to the host cell both enhance the virulence of the other type of E. coli. Our in vitro data demonstrate a molecular basis for a microbial interaction, which could result in increased severity of disease in vivo in individuals who are coinfected with ETEC and EPEC.

Population and virulence factor dynamics in fecalEscherichia colifrom healthy adults consuming weight control diets

Individual susceptibility to gastrointestinal infection is seen commonly in food poisoning outbreaks, but factors (such as diet) which may modulate this variability are understood poorly. Similarly, factors altering the population dynamics of enteric non-pathogenic Escherichia coli or of pathogenic E. coli containing toxin-signature DNA sequences in the colonic flora of healthy individuals are largely unknown. Feces were collected 4 times over a 12 week period from 41 healthy volunteer adults on a weight control diet (high or low in fiber). E. coli strains were examined by conventional culture followed by PCR for virulence genes stx1, stx2, eae and hlyA, and polymorphic β-glucuronidase. Total E. coli counts ranged from undetectable to 8.75 log10CFU/g feces and were unaffected by dietary fiber consumption or gender. Total E. coli counts were correlated positively with age (r = 0.401, P < 0.05). Fifty-eight percent (n = 24) of study individuals harboured more than 1 morph of β-glucuronidase, indicating the presence of more than 1 strain of E. coli. Virulence genes were detected in 12 of 41 adults, comprising 10 stx1, 3 stx2, 3 eae, and 0 hlyA, but occurrence was not associated with diet, gender, or age. Factors influencing strain mobility over time did not appear to include diet or gender, while the positive relationship between total E. coli numbers and increasing age suggests that some older individuals are "more permissive" to mobile E. coli, including those with toxin genes.Key words: Escherichia coli, virulence, healthy humans, diet.

Polymicrobial infections in children with diarrhoea in a rural area of Jordan

Polymicrobial infections associated with diarrhoea are common in developing countries. Stool specimens were collected from 220 patient children and 100 controls. Potential pathogenic agents isolated from 143 (65%) children were identified by molecular and standard microbiological methods. Co-infections with two or more agents were detected in 50 (35%) cases. Escherichia coli, Shigella dysenteriae, Giardia and Entamoeba histolytica were found to be predominant. The etiologic agents could not be determined in 77 (35%) cases. The most significant risk factors were the age, the education level of the mother and the use of non-chlorinated water. The high infection rate of diarrhoeal diseases is a strong indication that these pathogens circulate easily through the population.

Characterization of diarrhoeagenic Escherichia coli isolates in Jordanian children

In a prospective study carried out among Jordanian children in Amman, a total of 73/250 (29.2%) stool specimens were positive for 1 or more diarrhoeagenic Escherichia coli strains using a multiplex polymerase chain reaction method. This study indicated that diarrhoeagenic E. coli isolates were found frequently more in stools of children with diarrhoea (34%) than without diarrhoea (23.1%), but without any significant difference (p > 0.05). The predominant diarrhoeagenic E. coli strains associated with diarrhoea were enteropathogenic E. coli (11.3%), followed by enterotoxigenic E. coli (9.8%) and enteroaggrative E. coli (9%), whereas in the control group these were 4.3%, 11.1% and 6%, respectively. Enteroinvasive E. coli strains (2.9%) were found only in stools of children with diarrhoea. This study revealed the absence of enterohaemorrhagic E. coli in both diarrhoeal and control stools, and found that diarrhoeagenic E. coli isolates were highly resistance to tetracycline (55%), co-trimoxazole (60%) and ampicillin (89%), which are commonly used antibiotics in Jordan.

Serology and genetics of the flagellar antigen of Escherichia coli O157:H7a,7c

Among Escherichia coli strains of the O55:H7 serovar, which is considered the ancestor of Shiga toxin-producing E. coli (STEC) O157:H7, two subtypes, H7a,7b and H7a,7c (briefly, H7a,b and H7a,c, respectively), of the H7 flagellar antigen have been described previously [J. Wright and R. Villanueva, J. Hyg. (Camb.) 51:39-48, 1953; Y. A. Ratiner and V. A. Sinelnikova, Zh. Microbiol. Epidemiol. Immunobiol. 3:111-116, 1969). We have now studied 13 STEC O157:H7 strains and 1 O55:H7 strain that were epidemiologically unrelated, that originated from six countries on two continents, and that had different profiles when analyzed by multilocus enzyme electrophoresis, pulsed-field gel electrophoresis, and PCR for stx and eae. They were all found to possess the H7a,c flagellar antigen. Serum cross-absorption assays confirmed that their H antigens were indistinguishable from each other and from that of E. coli O55:H7a,c but differed from the standard H7a,b antigen of E. coli H test strain U5/41. It was shown by phage-mediated transduction that the flagellin genes for these two H-antigen subserotypes were alleles of the E. coli fliC locus. On the basis of the serological data obtained in this study and the molecular characteristics of E. coli fliC(H7) alleles recently published, it is inferred that H7a,c and H7a,b are the main serological subtypes of the group of E. coli H7 flagellins.

EPEC, EAEC and STEC in stool specimens: prevalence and molecular epidemiology of isolates

Stool specimens of Finns (n = 695) with (n = 603) and without (n = 92) diarrhea were studied for enteropathogenic (EPEC), enteroaggregative (EAEC) and Shiga toxin-producing (STEC) Escherichia coli by PCR. The specific isolates were subsequently investigated for their O:H serotypes and were genotyped by pulsed-field gel electrophoresis (PFGE). A subset (n = 506) of the diarrheal and all non-diarrheal specimens were also searched for conventional enteric bacterial pathogens by standard methods. Diarrheagenic E. coli were found in 5.5% and other enteric pathogens in 6.7% of the patients with and in 2.2% and 1.1% of the subjects without diarrhea, respectively. Campylobacter (3.8%), EPEC (3.2%) and Salmonella (2.0%) were the most common findings, and were detected in diarrheal patients only. STEC were associated with bloody diarrhea (8/9 isolates), whereas EAEC were equally common (1%) in diarrheal and non-diarrheal subjects. Great genomial heterogeneity was seen among diarrheagenic E. coli, and only one EPEC isolate belonged to the "classic" EPEC serogroup (O55).

matB, a common fimbrillin gene of Escherichia coli, expressed in a genetically conserved, virulent clonal group

A novel fimbrial type in Escherichia coli was identified and characterized. The expression of the fimbria was associated with the O18acK1H7 clonal group of E. coli, which cause newborn meningitis and septicemia when grown at low temperature; hence, it was named the Mat (meningitis associated and temperature regulated) fimbria. The fimbriae were purified from a fimA::cat sfaA::Gm fliC::St derivative of the O18K1H7 isolate E. coli IHE 3034. The purified Mat fimbrillin had an apparent molecular mass of 18 kDa and did not serologically cross-react with the type 1 or S fimbria of the same strain. The matB gene encoding the major fimbrillin was cloned from the genomic DNA of the fimA::cat sfaA::Gm fliC::St derivative of IHE 3034. The predicted MatB sequence was of 195 amino acids, contained a signal sequence of 22 residues, and did not show significant homology to any of the previously characterized fimbrial proteins. The DNA sequence of matB was 97.8% identical to a region from nucleotides 17882 to 18469 in the 6- to 8-min region of the E. coli K-12 chromosome, reported to encode a hypothetical protein. The 7-kb DNA fragment containing matB of IHE 3034 was found by restriction mapping and partial DNA sequencing to be highly similar to the corresponding region in the K-12 chromosome. Trans complementation of the matB::cat mutation in the IHE 3034 chromosome showed that matB in combination with matA or matC restored surface expression of the Mat fimbria. A total of 27 isolates representing K-12 strains and the major pathogroups of E. coli were analyzed for the presence of a matB homolog as well as for expression of the Mat fimbria. A conserved matB homolog was found in 25 isolates; however, expression of the Mat fimbriae was detected only in the O18acK1H7 isolates. Expression of the Mat fimbria was temperature regulated, with no or a very small amount of fimbriae or intracellular MatB fimbrillin being detected in cells cultivated at 37(o)C. Reverse transcriptase PCR and complementation assays with mat genes controlled by the inducible trc promoter indicated that regulation of Mat fimbria expression involved both transcriptional and posttranscriptional events.