Diarrheagenic Escherichia coli in children from Costa Rica

Genomic analysis of multidrug-resistant Escherichia coli from Urban Environmental water sources in Accra, Ghana, Provides Insights into public health implications

Wastewater discharge into the environment in resource-poor countries poses a threat to public health. Studies in this area within these countries are limited, and the use of high-throughput whole-genome sequencing technologies is lacking. Therefore, understanding of environmental impacts is inadequate. The present study investigated the antibiotic resistance profiles and diversity of beta-lactamases in Escherichia coli strains isolated from environmental water sources in Accra, Ghana. Microbiological analyses were conducted on wastewater samples from three hospitals, a sewage and wastewater treatment plant, and water samples from two urban surface water bodies. Confirmed isolates (N = 57) were selected for phenotypic antibiotic resistance profiles. Multi-drug-resistant isolates (n = 25) were genome sequenced using Illumina MiSeq sequencing technology and screened for sequence types, antibiotic resistance, virulence and beta-lactamase genes, and mobile genetic elements. Isolates were frequently resistant to ampicillin (63%), meropenem (47%), azithromycin (46%), and sulfamethoxazole-trimethoprim (42%). Twenty different sequence types (STs) were identified, including clinically relevant ones such as ST167 and ST21. Five isolates were assigned to novel STs: ST14531 (n = 2), ST14536, ST14537, and ST14538. The isolates belonged to phylogroups A (52%), B1 (44%), and B2 (4%) and carried β-lactamase (TEM-1B, TEM-1C, CTX-M-15, and blaDHA-1) and carbapenemase (OXA-1, OXA-181) resistance genes. Dominant plasmid replicons included Col440I (10.2%) and IncFIB (AP001918) (6.8%). Polluted urban environments in Accra are reservoirs for antibiotic-resistant bacteria, posing a substantial public health risk. The findings underscore the need for targeted public health interventions to mitigate the spread of antibiotic-resistant bacteria and protect public health.

A 6-year retrospective study of clinical features, microbiology, and genomics of Shiga toxin-producing Escherichia coli in children who presented to a tertiary referral hospital in Costa Rica

Shiga-toxin-producing Escherichia coli (STEC) is associated with diarrhea and hemolytic uremic syndrome (HUS). STEC infections in Costa Rica are rarely reported in children. We gathered all the records of STEC infections in children documented at the National Children's Hospital, a tertiary referral hospital, from 2015 to 2020. Clinical, microbiological, and genomic information were analyzed and summarized. A total of 3,768 diarrheal episodes were reviewed. Among them, 31 STEC were characterized (29 fecal, 1 urine, and 1 bloodstream infection). The prevalence of diarrheal disease due to STEC was estimated at 0.8% (n = 29/3,768), and HUS development was 6.4% (n = 2/31). The stx1 gene was found in 77% (n = 24/31) of STEC strains. In silico genomic predictions revealed a predominant prevalence of serotype O118/O152:H2, accompanied by a cluster exhibiting allele differences ranging from 33 to 8, using a core-genome multilocus sequence typing (cgMLST) approach. This is the first study using a genomic approach for STEC infections in Costa Rica.IMPORTANCEThis study provides a comprehensive description of clinical, microbiological, genomic, and demographic data from patients who attended the only pediatric hospital in Costa Rica with Shiga-toxin-producing Escherichia coli (STEC) infections. Despite the low prevalence of STEC infections, we found a predominant serotype O118/O152:H2, highlighting the pivotal role of genomics in understanding the epidemiology of public health threats such as STEC. Employing a genomic approach for this pathogen for the first time in Costa Rica, we identified a higher prevalence of STEC in children under 2 years old, especially those with gastrointestinal comorbidities, residing in densely populated regions. Limitations such as potential geographic bias and lack of strains due to direct molecular diagnostics are acknowledged, emphasizing the need for continued surveillance to uncover the true extent of circulating serotypes and potential outbreaks in Costa Rica.

Phylogenetic Groups, Pathotypes and Antimicrobial Resistance of Escherichia coli Isolated from Western Lowland Gorilla Faeces (Gorilla gorilla gorilla) of Moukalaba-Doudou National Park (MDNP)

(1) Background: Terrestrial mammals in protected areas have been identified as a potential source of antimicrobial-resistant bacteria. Studies on antimicrobial resistance in gorillas have already been conducted. Thus, this study aimed to describe the phylogroups, pathotypes and prevalence of antimicrobial resistance of Escherichia coli isolated from western lowland gorilla's faeces living in MDNP. (2) Materials and Methods: Ninety-six faecal samples were collected from western lowland gorillas (Gorilla gorilla gorilla) during daily monitoring in the MDNP. Sixty-four E. coli isolates were obtained and screened for phylogenetic and pathotype group genes by polymerase chain reaction (PCR) after DNA extraction. In addition, antimicrobial susceptibility was determined by the disk diffusion method on Mueller Hinton agar. (3) Results: Sixty-four (64%) isolates of E. coli were obtained from samples. A high level of resistance to the beta-lactam family, a moderate rate for fluoroquinolone and a low rate for aminoglycoside was obtained. All E. coli isolates were positive in phylogroup PCR with a predominance of A (69% ± 11.36%), followed by B2 (20% ± 19.89%) and B1 (10% ± 8.90%) and low prevalence for D (1% ± 3.04%). In addition, twenty E. coli isolates (31%) were positive for pathotype PCR, such as EPEC (85% ± 10.82%) and EPEC/EHEC (15% ± 5.18%) that were obtained in this study. The majority of these MDR E. coli (DECs) belonged to phylogenetic group A, followed by MDR E. coli (DECs) belonging to group B2. (4) Conclusion: This study is the first description of MDR E. coli (DECs) assigned to phylogroup A in western lowland gorillas from the MDNP in Gabon. Thus, wild gorillas in MDNP could be considered as asymptomatic carriers of potential pathogenic MDR E. coli (DECs) that may present a potential risk to human health.

Enteroinvasive Escherichia coli O96:H19 is an Emergent Biofilm-Forming Pathogen

Enteroinvasive Escherichia coli (EIEC) is a diarrheagenic E. coli pathotype carrying a virulence plasmid that encodes a type III secretion system (TTSS) directly implicated in bacterial cell invasion. Since 2012, EIEC serotype O96:H19 has been recognized in Europe, Colombia, and most recently Uruguay. In addition to the invasion phenotype, the strains isolated from Colombian children with moderate-to-severe gastroenteritis had a strong biofilm formation phenotype, and as a result, they are referred to as biofilm-forming enteroinvasive E. coli (BF-EIEC). The objective of this study was to characterize the biofilm formation phenotype of the BF-EIEC O96:H19 strain 52.1 isolated from a child with moderate-to-severe gastroenteritis in Colombia. Random mutagenesis using Tn5 transposons identified 100 mutants unable to form biofilm; 20 of those had mutations within the pgaABCD operon. Site-directed mutagenesis of pgaB and pgaC confirmed the importance of these genes in N-acetylglucosamine-mediated biofilm formation. Both biofilm formation and TTSS-mediated host cell invasion were associated with host cell damage on the basis of cytotoxic assays comparing the wild type, invasion gene mutants, and biofilm formation mutants. Multilocus sequence typing-based phylogenetic analysis showed that BF-EIEC strain 52.1 does not cluster with classic EIEC serotype strains. Instead, BF-EIEC strain 52.1 clusters with EIEC serotype O96:H19 strains described in Europe and Uruguay. In conclusion, BF-EIEC O96:H19, an emerging pathogen associated with moderate-to-severe acute gastroenteritis in children under 5 years of age in Colombia, invades cells and has a strong biofilm formation capability. Both phenotypes are independently associated with in vitro cell cytotoxicity, and they may explain, at least in part, the higher disease severity reported in Europe and Latin America. IMPORTANCE Enteroinvasive Escherichia coli (EIEC), a close relative of Shigella, is implicated in dysenteric diarrhea. EIEC pathogenicity involves cell invasion mediated by effector proteins delivered by a type III secretion system (TTSS) that disrupt the cell cytoskeleton. These proteins and the VirF global regulator are encoded by a large (>200 kb) invasion plasmid (pINV). This study reports an emergent EIEC possessing a cell invasion phenotype and a strong polysaccharide matrix-mediated biofilm formation phenotype. Both phenotypes contribute to host cell cytotoxicity in vitro and may contribute to the severe disease reported among children and adults in Europe and Latin America.

Occurrence and Determination of Antimicrobial Resistant Escherichia coli Isolates in Fish and Vegetables as Indicator Organism of Faecal Contamination in Dar es Salaam, Tanzania

Escherichia coli such as E. coli O157:H7, a non-sorbitol-fermenting (NSF) E. coli, is an essential human pathogen among other common zoonotic pathogens carried by animals especially cattle. They are discharged through cattle faeces into the environment. With the increasing practice of urban farming, livestock manure is used as organic fertiliser in either fish ponds or vegetable gardens. This practice increases the risk of transmission of such pathogens to humans. This study aimed at determining the occurrence, antimicrobial resistance profiles, and genetic relatedness of E. coli isolates from manure, vegetables, and fish. Microbiological standard methods were used to isolate and identify E. coli isolates from manure, vegetable, and fish samples. Confirmed isolates on biochemical tests were tested for resistance against six antibiotics using the disc diffusion method. Enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR) typing method was used to generate fingerprints and determine the genetic relatedness of the E. coli isolates. Of 156 samples including 89 manure, 53 vegetables, and 16 fish, 36 (23.1%) samples were positive for E. coli from where a total of 48 E. coli different isolates were recovered that were subjected to antimicrobial susceptibility testing and genetic relatedness. Of these isolates, 25 (52.1%) were resistant to at least one antimicrobial agent and 12 (48.0%) showed multidrug resistance. ERIC-PCR profiles of E. coli isolates from manure, vegetables, and fish showed genetic diversity with genetic relatedness ranging from 74.5% to 100%. Nine phylogenetic clusters (I–IX) determined at 90% threshold level of genetic relatedness were identified among the isolates. This study determined the occurrence, antimicrobial resistant patterns, and genetic diversity of antimicrobial-resistant E. coli isolates from different sources. This study showed the potential of microbial health risk to humans through contamination, and hence, it is necessary to monitor and improve husbandry practices in urban farming.

Pathotyping and Antibiotic Resistance Profiling of Escherichia coli Isolates from Children with Acute Diarrhea in Amatole District Municipality of Eastern Cape, South Africa

BACKGROUND

Diarrhea has been reported as the leading cause of childhood mortality and morbidity globally but with disproportionate impacts in developing nations. Among bacterial etiologic agents of diarrhea, diarrheagenic Escherichia coli is the main cause of the disease among children under the age of 5 years. This study is aimed at determining the prevalence and antibiogram pattern of diarrheagenic Escherichia coli (DEC) pathotypes associated with diarrhea cases in the study area.

METHODS

A total of 120 presumptive isolates of E. coli were obtained from diarrheal stool samples from male and female patients below 12 years of age using chromogenic agar. Confirmation of the isolates and screening for virulence genes were determined by polymerase chain reaction (PCR) while antimicrobial susceptibility testing was performed using the disk diffusion method. The presence of antibiotic resistance genes to chloramphenicol and tetracycline among the confirmed isolates was also profiled by PCR based on the observed phenotypic resistance pattern.

RESULTS

Of the 120 presumptive isolates, 88.3% (106/120) were confirmed as E. coli through PCR. The molecular pathotyping of the confirmed isolates showed their distribution as 41% (43/106) of diffusely adhering E. coli (DAEC), 17% (18/106) of enterohemorrhagic E. coli (EHEC), 17% (18/106) of enteropathogenic E. coli (EPEC), and 10% (11/106) of enteroinvasive E. coli (EIEC), while enteroaggregative E. coli (EAEC) and enterotoxigenic E. coli (ETEC) were not detected, and the remaining 15% did not belong to any pathotype. Notably, high resistance of the isolates to commonly used antimicrobials was observed as follows: ampicillin (98%), chloramphenicol (94%), trimethoprim-sulfamethoxazole (96%), and tetracycline (90.6%), while a relatively low number of the confirmed isolates were resistant to ciprofloxacin (45%) and imipenem (36%). In addition, 94% of the isolates that exhibited phenotypic resistance against chloramphenicol harbored the catA1 resistance gene while 89% that showed resistance to tetracycline had tetA genes.

CONCLUSIONS

These findings showed that DEC could be considered as the leading etiologic bacterial agent responsible for diarrhea in the study community, and the observable high degree of resistance of the isolates to antimicrobial agents is of huge significance, calling for stakeholders to adopt and consolidate the existing antimicrobial stewardship scheme of the government, in order to ensure an uncompromised public health.

Prevalence of Enteropathogens and Virulence Traits in Brazilian Children With and Without Diarrhea

The use of molecular diagnostics for pathogen detection in epidemiological studies have allowed us to get a wider view of the pathogens associated with diarrhea, but the presence of enteropathogens in asymptomatic individuals has raised several challenges in understanding the etiology of diarrhea, and the use of these platforms in clinical diagnosis as well. To characterize the presence of the most relevant bacterial enteropathogens in diarrheal episodes, we evaluated here the prevalence of diarrheagenic E. coli pathotypes, Salmonella spp., and Yersinia enterocolitica in stool samples of children with and without diarrhea using real-time quantitative PCR (qPCR). We found that the presence of genetic markers associated with bacterial pathogens was significantly higher in stool samples from the diarrhea group compared to the control (P < 0.001). Bacterial loads in samples positive for eae and aggR markers were also determined. Compared to samples from asymptomatic children, a significantly higher number of copies of the eae gene were found in diarrhea samples. Also, the presence of genetic markers associated with STEC strains with clinical significance was evaluated in eae-positive samples by high-throughput real-time PCR. The data presented herein demonstrated that asymptomatic children of an urban area in Brazil might be enteropathogen reservoirs, especially for STEC.

Community-Acquired Antimicrobial Resistant Enterobacteriaceae in Central America: A One Health Systematic Review

Community-acquired antimicrobial resistant Enterobacteriaceae (CA-ARE) are an increasingly important issue around the world. Characterizing the distribution of regionally specific patterns of resistance is important to contextualize and develop locally relevant interventions. This systematic review adopts a One Health framework considering the health of humans, animals, and the environment to describe CA-ARE in Central America. Twenty studies were identified that focused on antimicrobial resistance (AMR) in Enterobacteriaceae. Studies on CA-ARE in Central America characterized resistance from diverse sources, including humans (n = 12), animals (n = 4), the environment (n = 2), and combinations of these categories (n = 2). A limited number of studies assessed prevalence of clinically important AMR, including carbapenem resistance (n = 3), third generation cephalosporin resistance (n = 7), colistin resistance (n = 2), extended spectrum beta-lactamase (ESBL) production (n = 4), or multidrug resistance (n = 4). This review highlights significant gaps in our current understanding of CA-ARE in Central America, most notably a general dearth of research, which requires increased investment and research on CA-ARE as well as AMR more broadly.

Phylogenic classification and virulence genes profiles of uropathogenic E. coli and diarrhegenic E. coli strains isolated from community acquired infections

The emergence of E.coli strains displaying patterns of virulence genes from different pathotypes shows that the current classification of E.coli pathotypes may be not enough, the study aimed to compare the phylogenetic groups and urovirulence genes of uropathogenic Escherichia coli (UPEC) and diarrheagenic E.coli (DEC) strains to extend the knowledge of E.coli classification into different pathotypes. A total of 173 UPEC and DEC strains were examined for phylogenetic typing and urovirulence genes by PCR amplifications. In contrast to most reports, phylogenetic group A was the most prevalent in both UPEC and DEC strains, followed by B2 group. Amplification assays revealed that 89.32% and 94.29% of UPEC and DEC strains, respectively, carried at least one of the urovirulence genes, 49.5% and 31.4% of UPEC and DEC strains, respectively, carried ≥ 2 of the urovirulence genes, fim H gene was the most prevalent (66.9% and 91.4%) in UPEC and DEC strains respectively. Twenty different patterns of virulence genes were identified in UPEC while 5 different patterns in DEC strains. Strains with combined virulence patterns of four or five genes were belonged to phylogenetic group B2. Our finding showed a closer relationship between the DEC and UPEC, so raised the suggestion that some DEC strains might be potential uropathogens. These findings also provide different insights into the phylogenetic classification of E. coli as pathogenic or commensals where group A can be an important pathogenic type as well as into the classification as intestinal or extra- intestinal virulence factors.

Diarrheagenic Escherichia coli in Costa Rican children: a 9-year retrospective study

Objectives

This study aimed to estimate diarrheagenic Escherichia coli (DEC) prevalence among pediatric patients with diarrhea at the Costa Rican National Children’s Hospital-Social Security Service (Hospital Nacional de Niños-Caja Costarricense del Seguro Social; HNN-CCSS). DEC variations with respect to rainfall, presence of coinfections, and DEC antimicrobial resistance were also investigated.

Results

A retrospective observational study from January 2008 to December 2016 was conducted. A total of 12 247 gastroenteritis records were analyzed. Annual DEC prevalence ranged from 2.7% (2008) to 9.0% (2013). The most prevalent pathotypes were enteroaggregative E. coli (EAEC) [n = 189 (31%)], enteropathogenic E. coli (EPEC) [n = 145 (24%)] and enteroinvasive E. coli (EIEC) [n = 91 (15%)]. A reduction in the probability of EAEC gastroenteritis was detected as rainfall rose above 200 mm/mo. [(Generalized Additive Model (GAM), p = 0.04)]. Coinfections were observed mainly between EPEC and Campylobacter spp. (10%). Antimicrobial resistance occurred in 0.6%, 29%, and 42% of DEC for ciprofloxacin, trimethoprim/sulfamethoxazole, and ampicillin, respectively.

Molecular diagnosis of diarrheagenic Escherichia coli isolated from Psittaciformes of illegal wildlife trade

ABSTRACT: Diarrheagenic Escherichia coli (DEC) are considered one of the major causes of human diarrhea in developing countries. Some studies have pointed wild birds as important reservoirs for these pathogens. However, scarce species from the Psittaciformes order have been investigated. This study aimed to evaluate the presence of DEC strains in Psittaciformes from illegal wildlife trade. A total of 78 E. coli strains isolated from cloacal swab samples of 167 Psittaciformes in the Ceará State, Brazil, were evaluated regarding the presence of the following DEC virulence genes by polymerase chain reaction (PCR): eaeA and bfpA genes (Enteropathogenic E. coli - EPEC); stx1 and stx2 (Shiga toxin-producing E. coli - STEC); estA and eltB (Enterotoxigenic E. coli - ETEC); ipaH (Enteroinvasive E. coli - EIEC); aatA and aaiC (Enteroaggregative E. coli - EAEC). Positive strains for eaeA and bfpA genes were considered typical EPEC, while strain positive exclusively for the eaeA gene were classified as atypical EPEC. The eaeA gene was identified in 20 E. coli strains and bfpA in 22 isolates. In addition, 11 and 9 belonged to tEPEC and aEPEC, respectively. No strain was positive for stx1 or stx2. A total of 47 (60.3%) strains and a total of 136 birds (81.4%) were negative for the remaining DEC pathotypes investigated. In conclusion, psittacine from illegal wildlife trade in Ceará State, Brazil, presented a relevant prevalence of typical and atypical EPEC, potentially playing a role as reservoirs of DEC strains in the environment. Thus, proper control measures must be adopted to block the spread of these pathogens.

Molecular Epidemiology of Extended-Spectrum β-Lactamase-Producing Escherichia coli Pathotypes in Diarrheal Children from Low Socioeconomic Status Communities in Bihar, India: Emergence of the CTX-M Type

Background

Childhood diarrheal diseases remain highly endemic in India, but the emergence of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli among children with diarrhea in Bihar remains elusive. In this study, we determine and characterize ESBL-producing E coli pathotypes among hospitalized diarrheal preschool children living in low socioeconomic level communities in Bihar, India.

Materials and methods

The stool samples were collected everyday throughout the year for 2 consecutive years. In our study, we collected stool samples randomly from every fifth patient. Stool samples were collected from a total of 633 randomly selected diarrheal children (age: 0-60 months) belonging to 17 communities and screened for identification of virulent diarrheagenic E coli (DEC) pathotype (viz, enteropathogenic E coli [EPEC], enteroaggregative E coli [EAEC], enterotoxigenic E coli [ETEC], enteroinvasive E coli [EIEC], and enterohemorrhagic E coli [EHEC]) by a multiplex polymerase chain reaction (PCR) assay. Furthermore, ESBLs were screened by conventional antibiotic resistance pattern testing and later characterized for the presence of β-lactamase (bla) genes by PCR and DNA sequencing.

Results

Diarrheagenic E coli was detected in 191 cases (30.2%) of the total 633 diarrheic children. Maximum occurrence of DEC was found in ≤12 months age group (72.7%) with prevalence of the EAEC pathotype. Most isolates were resistant to ampicillin, ciprofloxacin, piperacillin, levofloxacin, ceftazidime, cefotaxime, ceftriaxone, and gentamicin, whereas over 96% of them were sensitive to amikacin. About 37.6% of total 191 DEC isolates were ESBL producers (n = 72), being prevalent among ETEC (n = 35; 18.32%), followed by EPEC (n = 21; 10.9%), EAEC (n = 13; 6.8%), and EIEC (n = 3; 1.57%). Interestingly, the commonest β-lactamase was CTX-M type (bla_CTX-M) in 86.1% (n = 62) of the ESBL isolates, followed by bla_SHV (n = 49; 68%), bla_TEM (n = 37; 51.8%), and bla_OXA (n = 21; 29.1%) determinants. Resistance of ESBL isolates was mostly related to ampicillin (100%), ceftriaxone (98.1%), cefotaxime (92.4%), gentamicin (74.1%), and levofloxacin (73.2%), whereas best antimicrobial activities were observed for piperacillin-tazobactam, amikacin, meropenem, and imipenem.

Conclusions

This study revealed that EAEC (72.1%) is the predominant pathotype in Bihar, significantly high in ≤12 months age group children (P = .04). Moreover, the widespread prevalence of ESBLs in children, especially the CTX-M type, is of great concern, which requires monitoring of infection control measures through efficient antimicrobial management and detection of ESBL-producing isolates.

Phylogenetic background of enterotoxigenic and enteroinvasive Escherichia coli from patients with diarrhea in Sirjan, Iran

BACKGROUND AND OBJECTIVES

Diarrheagenic Escherichia coli (DEC) strains are a major cause of intestinal syndromes in the developing countries. The aim of this study was to determine the prevalence of enterotoxigenic E. coli (ETEC) and enteroinvasive E. coli (EIEC) in relation to phylogenetic background from patients with diarrhea.

MATERIALS AND METHODS

A total of 110 E. coli isolates were obtained from diarrhea patients in Sirjan, southeast of Iran. The E. coli isolates were confirmed using biochemical and bacteriological tests. DNA of E. coli isolates was extracted by boiling method and checked for existence of ETEC (LT and ST genes) and EIEC (ipaH gene) pathotypes and also characterize the phylogenetic groups on the basis of presence or absence of the chuA, yjaA genes and an anonymous DNA fragment, TspE4. C2 by multiplex PCR.

RESULTS

Out of 110 E. coli isolates, 32 (29.09%) were positive for ETEC (LT and ST genes) and 6 (5.45%) possessed EIEC (ipaH gene) pathotypes. Isolates fall into four phylogenetic groups: A (39.09%), B1 (20%), B2 (15.45%) and D (25.45%). Phylotyping of isolates of DEC indicated they were distributed in four phylogenetic groups including A (12 isolates), B1 (7), B2 (9) and D (10).

CONCLUSION

In this study, the DEC isolates were segregated into different phylogenetic groups. The majority of isolates belonged to phylo-groups A and D.

Antibiogram of E. coli serotypes isolated from children aged under five with acute diarrhea in Bahir Dar town

BACKGROUND

Diarrheal disease and its complications remain a major cause of morbidity and mortality in children. The prevalence and antibiogram of E. coli as causative agents of diarrhea vary from region to region, and even within countries in the same geographical area.

OBJECTIVES

To determine the serotype and antimicrobial susceptibility of E. coli in children under-five years of age.

METHODS

A cross-sectional study was conducted among 422 children with diarrhea from December 2011 to February 2012. Identification of E. coli and antimicrobial susceptibility testing were done following standard procedures.

RESULTS

The overall isolation rate of E. coli was 48.3%. Poly 2 sero-groups, poly 3 sero-groups, poly 4 sero-groups and E. coli O157:H7 accounted for 80 (39.2%), 40 (19.6%), 25 (12.3%), and 59 (28.9%) of the isolates, respectively. Poly 2 sero-groups, constituting isolates belonging to enteropathogenic E. coli were the most commonly isolated serotypes. E. coli exhibited high levels of antimicrobial resistance to ampicillin (86.8%), tetracycline (76%) and cotrimoxazole (76%). Low levels of resistance to ciprofloxacin (6.9%) and norfloxacin (9.3%) were documented.

CONCLUSION

High prevalence of diarrheagenic E. coli compounded by alarming antimicrobial resistances is a serious public health problem. Regular determination of antibiogram and public education are recommended.

Diarrheagenic Escherichia coli phylogroups are associated with antibiotic resistance and duration of diarrheal episode

Conventionally, in Escherichia coli, phylogenetic groups A and B1 are associated with commensal strains while B2 and D are associated with extraintestinal strains. The aim of this study was to evaluate diarrheagenic (DEC) and commensal E. coli phylogeny and its association with antibiotic resistance and clinical characteristics of the diarrheal episode. Phylogenetic groups and antibiotic resistance of 369 E. coli strains (commensal strains and DEC from children with or without diarrhea) isolated from Peruvian children <1 year of age were determined by a Clermont triplex PCR and Kirby-Bauer method, respectively. The distribution of the 369 E. coli strains among the 4 phylogenetic groups was A (40%), D (31%), B1 (21%), and B2 (8%). DEC-control strains were more associated with group A while DEC-diarrhea strains were more associated with group D (P < 0.05). There was a tendency (P = 0.06) for higher proportion of persistent diarrhea (≥14 days) among severe groups (B2 and D) in comparison with nonsevere groups (A and B1). Strains belonging to group D presented significantly higher percentages of multidrug resistance than the rest of the groups (P > 0.01). In summary, DEC-diarrhea strains were more associated with group D than strains from healthy controls.

CS21 positive multidrug-resistant ETEC clinical isolates from children with diarrhea are associated with self-aggregation, and adherence

BACKGROUND

Enterotoxigenic Escherichia coli (ETEC) colonize the human intestinal mucosa using pili and non-pili colonization factors (CFs). CS21 (also designated Longus) is one of the most prevalent CFs encoded by a 14 kb lng DNA cluster located in a virulence plasmid of ETEC; yet limited information is available on the prevalence of CS21 positive ETEC isolates in different countries. The aim of this study was to evaluate the prevalence of CS21 among ETEC clinical isolates from Mexican and Bangladeshi children under 5 years old with diarrhea and to determine the phenotypic and genotypic features of these isolates.

METHODS

ETEC clinical isolates positive to lngA gene were characterized by genotype, multidrug-resistance, self-aggregation, biofilm formation, and adherence to HT-29 cell line.

RESULTS

A collection of 303 E. coli clinical isolates were analyzed, the 81.51% (247/303) were identified as ETEC, 30.76% (76/247) were st (+)/lt (+), and 25.10% (62/247) were positive for the lngA gene. Among the lngA (+) ETECs identified, 50% of isolates (31/62) were positive for LngA protein. The most frequent serotype was O128ac:H12 found in 19.35% (12/62) of lngA (+) ETEC studied. Multidrug-resistance (MDR) lngA (+) ETEC isolates was identified in 65% (39/60), self-aggregation in 48.38% (30/62), and biofilm formation in 83.87% (52/62). ETEC lngA (+) isolates were able to adhere to HT-29 cells at different levels. Two lngA isogenic mutants were constructed in the ETEC E9034A and ETEC73332 clinical isolate, showing a 77% and 98% reduction in adherence, respectively with respect to the wild type.

CONCLUSION

ETEC isolates that have the lngA gene showed features associated with self-aggregation, and adherence to HT-29 cells, important characteristics in the human gut colonization process and pathogenesis.

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.

Evaluation of MALDI-TOF mass spectroscopy methods for determination of Escherichia coli pathotypes

It is rapidly becoming apparent that many E. coli pathotypes cause a considerable burden of human disease. Surveillance of these organisms is difficult because there are few or no simple, rapid methods for detecting and differentiating the different pathotypes. MALDI-TOF mass spectroscopy has recently been rapidly and enthusiastically adopted by many clinical laboratories as a diagnostic method because of its high throughput, relatively low cost, and adaptability to the laboratory workflow. To determine whether the method could be adapted for E. coli pathotype differentiation the Bruker Biotyper methodology and a second methodology adapted from the scientific literature were tested on isolates representing eight distinct pathotypes and two other groups of E. coli. A total of 136 isolates was used for this study. Results confirmed that the Bruker Biotyper methodology that included extraction of proteins from bacterial cells was capable of identifying E. coli isolates from all pathotypes to the species level and, furthermore, that the Bruker extraction and MALDI-TOF MS with the evaluation criteria developed in this work was effective for differentiating most pathotypes.

Molecular analysis of typical and atypical enteropathogenic Escherichia coli (EPEC) isolated from children with diarrhoea

Diarrhoea continues to be one of the most common causes of morbidity and mortality among infants and children in developing countries. To investigate the incidence, antimicrobial resistance and genetic relationships of enteropathogenic Escherichia coli (EPEC) in children with diarrhoea, a total of 612 stool specimens were collected in Tehran, Iran, and cultured to isolate strains of EPEC. The disc diffusion method was used to determine the susceptibility of the isolates according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. The presence of eae, stx and bfp-A genes was determined by PCR. The genetic relationships between EPEC isolates were determined by pulsed-field gel electrophoresis (PFGE). Out of the 412 strains of E. coli obtained from 612 diarrhoeal stool specimens, 23 (5.6 %) were identified as EPEC, of which seven (30.4 %) were classified as typical strains of EPEC and 16 (69.6 %) were classified as atypical. Out of the 23 EPEC isolates, 69.5 % were resistant to ampicillin, 39.1 % were resistant to tetracycline and cotrimoxazole, 30.4 % were resistant to cefpodoxime, ceftazidime, ceftriaxone and aztreonam, and 26.1 % were resistant to imipenem. The isolates were classified into 21 pulsotypes by PFGE profiles. The present study shows that typical and atypical EPEC isolates displayed considerable heterogeneity in PFGE profiles and EPEC infections were only sporadic in Tehran. Overall 69 % of isolates were resistant to at least one of the antibiotics tested.

Antibiotic Resistance of Escherichia coli Serotypes from Cochin Estuary

This study aimed at detecting the prevalence of antibiotic-resistant serotypes of Escherichia coli in Cochin estuary, India. E. coli strains were isolated during the period January 2010-December 2011 from five different stations set at Cochin estuary. Water samples from five different stations in Cochin estuary were collected on a monthly basis for a period of two years. Isolates were serotyped, antibiogram-phenotyped for twelve antimicrobial agents, and genotyped by polymerase chain reaction for uid gene that codes for β-D-glucuronidase. These E. coli strains from Cochin estuary were tested against twelve antibiotics to determine the prevalence of multiple antibiotic resistance among them. The results revealed that more than 53.33% of the isolates were multiple antibiotic resistant. Thirteen isolates showed resistance to sulphonamides and two of them contained the sul 1 gene. Class 1 integrons were detected in two E. coli strains which were resistant to more than seven antibiotics. In the present study, O serotyping, antibiotic sensitivity, and polymerase chain reaction were employed with the purpose of establishing the present distribution of multiple antibiotic-resistant serotypes, associated with E. coli isolated from different parts of Cochin estuary.

Immunization of mice with Lactobacillus casei expressing a beta-intimin fragment reduces intestinal colonization by Citrobacter rodentium

Enteropathogenic Escherichia coli (EPEC) is a common cause of diarrhea in children from developing countries. Intimate adhesion of the bacteria to intestinal cells occurs via binding of the adhesin intimin to the TIR receptor exposed on cell surfaces. Here, Lactobacillus casei expressing a fragment of β-intimin (L. casei-Int(cv)) was tested as mucosal vaccines in mice against intestinal colonization with the murine pathogen Citrobacter rodentium. Oral or sublingual immunization of C57BL/6 mice with L. casei-Int(cv) induced anti-Int(cv) IgA in feces but no IgG in sera. Conversely, anti-Int(cv) IgG was induced in the sera of mice after sublingual immunization with purified Int(cv). All vaccines were able to decrease C. rodentium recovery from feces. However, this reduction was more evident and sustained over time in mice immunized with L. casei-Int(cv) by the sublingual route. These mice also displayed an increase in interleukin 6 (IL-6) and gamma interferon (IFN-γ) secretion by spleen cells 10 days after infection. Additionally, oral or sublingual immunization of C3H/HePas mice, which are highly susceptible to C. rodentium infection, with L. casei-Int(cv) induced anti-Int(cv) antibodies and significantly increased survival after challenge. Immunohistological analysis of colon sections revealed that C. rodentium was located in deep fractions of the tissue from C3H/HePas mice immunized with L. casei whereas superficial staining was observed in colon sections from mice immunized with L. casei-Int(cv.) The results indicate that vaccines composed of L. casei expressing intimin may represent a promising approach and that the C3H/HePas infection model with C. rodentium can be used to evaluate potential vaccines against EPEC.

New molecular approaches in the diagnosis of acute diarrhea: advantages for clinicians and researchers

PURPOSE OF REVIEW

To provide an update of the advantages of new-generation molecular diagnostics as regards acute diarrhea, and to evaluate how they can help clinicians and researchers diagnose this condition.

RECENT FINDINGS

Thanks to real-time polymerase chain reaction techniques, many enteropathogens can now be identified simultaneously within hours. Most techniques are based on amplification of specific nucleotide sequences. With high-resolution melting analyses, microarrays, and metagenomic analyses, multiple genomic sequences can be evaluated in a single sample; thus, a wide range of enteropathogens can be evaluated in one run. Molecular techniques have elucidated the role of major enteropathogens such as norovirus and bocavirus and their evolving epidemiology. They have revealed novel transmission routes, also in food-borne diarrhea outbreaks, and have opened the way to new therapies and preventive measures, as well as to surveillance of emerging rotavirus strains after vaccine introduction.

SUMMARY

Molecular approaches are best suited for epidemiologic purposes and for selected clinical conditions such as early identification of treatable agents in at-risk patients, rather than for cases requiring only oral rehydration. In the field of acute diarrhea, the major application of molecular techniques is the identification of novel agents of gastroenteritis and their epidemiology.