Enteroaggregative Escherichia Coli Isolates Research Articles

Antimicrobial Susceptibility Patterns of Enteroaggregative E. coli, as the Most Common Diarrheagenic E. coli, Associated to Gastroenteritis Outbreaks in Iran

Background: Acute diarrhea, a leading cause of morbidity and mortality worldwide, still remains a major global health problem, especially among children in the developing countries. Diarrheagenic E. coli represent one of the most common etiological causes of diarrhea in children worldwide. Objectives: This study was conducted in order to determine the rate of Enteroaggregative E. coli (EAEC) among 50 E. coli isolates as well as its antimicrobial resistance patterns. Methods: A total of 50 Escherichia coli strains had been isolated among children under 5 years of age during 75 reported outbreaks in various provinces of Iran from October 2013 to May 2014. PCR was employed for the identification of different groups of diarrheagenic E. coli. Antimicrobial susceptibility testing was performed using disc diffusion methods. In addition, extended spectrum beta-lactamase (ESBL) production ability was checked by way of combination disc methods of CLSI. Minimum inhibitory concentration of cefotaxime, ceftriaxone, and ceftazidime in EAEC with the ability of ESBL production was determined using the micro-broth dilution method of CLSI. Results: Out of the 50 E. coli isolates, 17 were identified as Enteroaggregative E. coli (EAEC) in that they were positive for at least 1 of the 2 tested virulent genes: agg and aap. ESBL production ability was observed in 4/17 (23.5%) EAEC isolates. MIC of cefotaxime and ceftriaxone in ESBL positive EAEC varied between 8 - 32 µg/mL and 8 - 64 µg/mL, respectively. Resistance to ampicillin and nalidixic-acid (47.1%), trimethoprim/sulfamethoxazole (41.2%), and ciprofloxacin (11.8%) was observed among the EAEC isolates. No evidence of resistance to gentamycin and meropenem was detected. Conclusions: This research has revealed that the most common type of diarrheagenic E. coli among children, who were affected in the diarrheal outbreak in different cities of the country, is Enteroaggregative E. coli (34%). The rate of ESBL positive cases in EAEC isolates were 23.5 %.

Clonality, virulence and antimicrobial resistance of enteroaggregative Escherichia coli from Mirzapur, Bangladesh.

PurposeThis study investigates the virulence and antimicrobial resistance in association with common clonal complexes (CCs) of enteroaggregative Escherichia coli (EAEC) isolated from Bangladesh. The aim was to determine whether specific CCs were more likely to be associated with putative virulence genes and/or antimicrobial resistance.MethodologyThe presence of 15 virulence genes (by PCR) and susceptibility to 18 antibiotics were determined for 151 EAEC isolated from cases and controls during an intestinal infectious disease study carried out between 2007–2011 in the rural setting of Mirzapur, Bangladesh (Kotloff KL, Blackwelder WC, Nasrin D, Nataro JP, Farag TH et al. Clin Infect Dis 2012;55:S232–S245). These data were then analysed in the context of previously determined serotypes and clonal complexes defined by multi-locus sequence typing.ResultsOverall there was no association between the presence of virulence or antimicrobial resistance genes in isolates of EAEC from cases versus controls. However, when stratified by clonal complex (CC) one CC associated with cases harboured more virulence factors (CC40) and one CC harboured more resistance genes (CC38) than the average. There was no direct link between the virulence gene content and antibiotic resistance. Strains within a single CC had variable virulence and resistance gene content indicating independent and multiple gene acquisitions over time.ConclusionIn Bangladesh, there are multiple clonal complexes of EAEC harbouring a variety of virulence and resistance genes. The emergence of two of the most successful clones appeared to be linked to either increased virulence (CC40) or antimicrobial resistance (CC38), but increased resistance and virulence were not found in the same clonal complexes.

Comparison of phenotypic and WGS-derived antimicrobial resistance profiles of enteroaggregative Escherichia coli isolated from cases of diarrhoeal disease in England, 2015–16

Phenotypic and genotypic methods for the detection of antimicrobial resistance (AMR) in enteroaggregative Escherichia coli (EAEC) were compared and evaluated. WGS data from 155 isolates of EAEC isolated between June 2015 and December 2016 were mapped to genes known to be associated with phenotypic AMR. Phenotypic and genotypic testing of 155 isolates against 10 antimicrobial classes resulted in a total of 25 (1.6%) discordant results of a possible 1550 isolate/antimicrobial combinations. Twenty-three of the mismatches were observed in streptomycin or sulphonamide resistance profiles. These discrepancies were associated with either insertions or truncations in the genes predicted to confer resistance, or in their promotors, rendering them non-functional, or with the presence of aadA variants associated with reduced expression. The most common resistances detected were to ampicillin (56.1%), the sulphonamides (49.7%) and trimethoprim (48.4%). The presence of CTX-M ESBL variants and/or acquired AmpC was detected in 87 of 155 (56.1%) isolates and 18 of 155 (11.6%) isolates were resistant to ciprofloxacin. Eighty-eight (56.8%) isolates were MDR. Phenotypic and genome-derived AMR comparisons showed good correlation for EAEC. A better understanding of the role of allelic variants, specific gene combinations and promoter/attenuator mechanisms in the phenotypic manifestation will improve our ability to provide a robust interpretation of the data for surveillance purposes and, ultimately, in the clinical setting.

Distribution and Molecular Characterization of Enteroaggregative Escherichia coli Isolated from Children in A Case-control Study of Acute Diarrhea in Thailand

Background: Enteroaggregative Escherichia coli (EAEC) is a major cause of acute diarrhea in children, adults, and travelers as well as an important cause of persistent diarrhea. Due to the limited information on EAEC virulence genes, EAEC isolates isolated from children with diarrhea and asymptomatic controls in Thailand were characterized for the presence of virulence factors. Method: A study of diarrhea etiology in children from Thailand was conducted during 2008-2009 and 301 EAEC isolates were identified by pCVD432 probe/hybridization assays from diarrhea cases and controls. A total of 200 EAEC isolates were further characterized by PCR for EAEC genotypes, aggregative adherence fimbria (AAF/I-AAF/ IV), serine protease autotransporters of Enterobacteriaceae (SPATEs) class I & II, and enterotoxin genes. Results: The prevalence of EAEC isolates in this study were 7.7% and 9.1% among cases (n=1803) and controls (n=1790). Of 200 EAEC isolates, 69% of case and 58% of control isolates were classified as typical EAEC genotype. AAF/I (aggA) was the major fimbria type for cases (37%) and controls (23%), followed by AAF/III (9%, 13%), AAF/II (11%, 17%) and AAF/IV (5%, 3%). In confirmed cases, class II SPATE-sepA (19%, 7%) and pic (75%, 60%) and enterotoxin-set (75%, 61%) genes were detected in significantly more strains when compared to the controls. Additionally, typical EAEC isolates containing genes for AAF/I, Class II SPATEs (sepA, pic), and enterotoxin (set) were detected more frequently in cases than controls (P value<0.05). Conclusion: This study suggests virulence gene heterogeneity of EAEC isolated from children with diarrhea as compared to asymptomatic controls, and that specific virulence genes are associated with diarrhea.

Virulence determinants in enteroaggregative Escherichia coli from North India and their interaction in in vitro organ culture system.

Enteroaggregative Escherichia coli (EAEC) is an important diarrhoeal pathogen causing diseases in multiple epidemiological and clinical settings. In developing countries like India, diarrhoeal diseases are one of the major killers among paediatric population and oddly, few studies are available from Indian paediatric population on the variability of EAEC virulence genes. In this study, we examined the distribution of plasmid and chromosomal-encoded virulence determinants in EAEC isolates, and analysed cytokines response generated against EAEC with specific aggregative adherence fimbriae (AAF) type in duodenal biopsies using in vitro organ culture (IVOC) mimicking in vivo conditions. Different virulence marker combinations among strains were reflected as a function of specific adhesins signifying EAEC heterogeneity. fis gene emerged as an important genetic marker apart from aggA and aap Further, EAEC infection in IVOC showed upregulation of IL-8, IL-1β, IL-6, TNF-α and TLR-5 expression. EAEC with AAFII induced significant TLR-5 and IL-8 response, conceivably owing to more pathogenicity markers. This study sheds light on the pattern of EAEC pathotypes prevalent in North Indian paediatric population and highlights the presence of unique virulence combinations in pathogenic strains. Thus, evident diversity in EAEC virulence and multifaceted bacteria-host crosstalk can provide useful insights for the strategic management of diarrhoeal diseases in India, where diarrhoeal outbreaks are more frequent.

Phenotypic and genotypic characterization of enteroaggregative Escherichia coli isolates from pediatric population in Pakistan.

Enteroaggregative Escherichia coli (EAEC) are a leading cause of diarrhea among children. The objective of this study was to define the frequency of EAEC among diarrheal children from flood-affected areas as well as sporadic cases, determine multidrug resistance, and evaluation of virulence using an in vivo model of pathogenesis. Stool samples were collected from 225 diarrheal children from 2010 to 2011 from flood-affected areas as well as from sporadic cases in Pakistan. Identified EAEC isolates were characterized by phylogrouping, antibiotic resistance patterns including the extended-spectrum beta lactamase spectrum, single nucleotide polymorphism detection in gyrA and parC, and virulence potential using wax worm, G. mellonella. A total of 35 (12.5%) confirmed EAEC isolates were identified among 225 E. coli isolates. EAEC isolates displayed high resistance to tetracycline, ampicillin, and cefaclor. A total of 34.28% were ESBL positive. Single nucleotide polymorphism detection revealed 37.14% and 68.57% isolates were positive for SNPs in gyrA (A660 -T660 ) and parC (C330 -T330 ), respectively. Phylogrouping revealed that B2 phylogroup was more prevalent among all EAEC isolates tested followed by D, A, B1, and non-typeable (NT). Infection of G. mellonella with EAEC showed that killing infective dose was 100% higher than E. coli DH5 alpha control. EAEC are prevalent among Pakistani children with diarrhea, they are highly resistant to antibiotics, and predominantly fall into B2 phylogroup. Epidemiologic surveillance of EAEC and other E. coli pathotypes is critical to assess not only the role of these pathogens in diarrheal disease but also to determine the extent of multidrug resistance among the population.

Evaluation of Prevalence, Homology and Immunogenicity of Dispersin among Enteroaggregative Escherichia coli Isolates from Iran.

Background:Diarrhea, caused by enteroaggregative Escherichia coli (EAEC), is an important infection leading toillness and death. Numerous virulent factors have been described in EAEC. However, their prevalence was highly variable among EAECs of distinct geographic locations. Studies have shown that dispersin (antiaggregation protein, aap) is one of the important and abundant virulent factors in EAEC. In this study, we aimed to determine the presence, conservation, and immunogenicity of aap gene in EAEC isolated from Iranian patients.Methods:PCR amplification of aap gene in the EAEC isolates was performed, and the aap gene was cloned in pBAD-gIIIA vector. The sequence of aap gene was analyzed using the ExPASy and BLAST tools. The expression of aap gene was performed in E. coli Top10, and expression confirmation was carried out by SDS-PAGE and Western-blot techniques. Rabbits were immunized with purified dispersin protein emulsified with Freund’s adjuvant. Sera were collected and examined for antibody response. Finally, in vitro efficacy of dispersin and anti-dispersin was evaluated.Results:The results of PCR showed the presence of aap gene in all of the EAEC isolates with significant homology. Finally, the significant difference between the levels of IgG response in dispersin-injected rabbits and control group was observed.Conclusion:Our results were in accordance with other studies that reported the presence of dispersin in the EAEC isolates with high conservation and immunogenicity. Hence, dispersin could be a promising candidate for any probable prevention against EAEC infections.

Comparative genetic characterization of Enteroaggregative Escherichia coli strains recovered from clinical and non-clinical settings.

The origin of pathogenic Enteroaggregative Escherichia coli (EAEC), a major causative agent of childhood diarrhea worldwide, remains ill-defined. The objective of this study was to determine the relative prevalence of EAEC in clinical and non-clinical sources and compare their genetic characteristics in order to identify strains that rarely and commonly cause human diarrhea. The virulence gene astA was commonly detectable in both clinical and non-clinical EAEC, while clinical isolates, but not the non-clinical strains, were consistently found to harbor other virulence factors such as aap (32%), aatA (18%) and aggR (11%). MLST analysis revealed the extremely high diversity of EAEC ST types, which can be grouped into three categories including: (i) non-clinical EAEC that rarely cause human infections; (ii) virulent strains recoverable in diarrhea patients that are also commonly found in the non-clinical sources; (iii) organisms causing human infections but rarely recoverable in the non-clinical setting. In addition, the high resistance in these EAEC isolates in particular resistance to fluoroquinolones and cephalosporins raised a huge concern for clinical EAEC infection control. The data from this study suggests that EAEC strains were diversely distributed in non-clinical and clinical setting and some of the clinical isolates may originate from the non-clinical setting.

Genetic diversity and antibiogram profile of diarrhoeagenic Escherichia coli pathotypes isolated from human, animal, foods and associated environmental sources

IntroductionInfectious diarrhoea particularly due to pathogenic bacteria is a major health problem in developing countries, including India. Despite significant reports of diarrhoeagenic Escherichia coli (DEC) pathotypes around the globe, studies which address genetic relatedness, antibiogram profile and their correlation with respect to their isolation from different sources are sparse. The present study determines isolation and identification of DEC pathotypes from different sources, their genetic characterisation, antibiogram profile and their correlation if any.Materials and methodsA total of 336 samples comprising diarrhoeic stool samples from infants (n=103), young animal (n=106), foods (n=68) and associated environmental sources (n=59) were collected from Bareilly region of India. All the samples were screened by using standard microbiological methods for the detection of E. coli. The identified E. coli were then confirmed as DEC pathotypes using polymerase chain reaction–based assays. Those DEC pathotypes identified as Enteroaggregative E. coli (EAEC) were further confirmed using HEp-2 adherence assay. All the isolated DEC pathotypes were studied for their genetic diversity using pulsed-field gel electrophoresis (PFGE), and antimicrobial susceptibility testing was performed by using disc diffusion method as per Clinical Laboratory Standards Institute guidelines.Results and discussionOf the four DEC pathotypes investigated, EAEC was found to be the predominant pathogen with an isolation rate of 16.5% from infants, 17.9% from young animals, 16.2% from foods and 3.4% from the associated environmental sources. These EAEC isolates, on further characterisation, revealed predominance of ‘atypical’ EAEC, with an isolation rate of 10.7% from infants, 15.1% from young animals, 16.2% from foods, and 3.4% from the associated environmental sources. On PFGE analysis, discrimination was evident within DEC pathotypes as 52 unique pulsotypes were observed for 59 recovered DEC pathotypes. However, a few EAEC isolates were found to be clonal (clusters A, B, C, D, F, G, and H) irrespective of their source of isolation, suggests sharing and/or circulation among different sources. Further, a high antibiotic resistance pattern was observed among isolated DEC pathotypes as almost 86.4% of isolates were found to be resistant against ≥3 tested drugs.

Distribution of Virulence Genes, Enterotoxin and Biofilm Formation Among Enteroaggregative Escherichia Coli (EAEC) Strains Isolated From Stools of Children With Diarrhea in South East Iran

Background: Enteroaggregative Escherichia coli (EAEC) is commonly associated with pediatric diarrhea, in developing countries. Objectives: In this study, we investigated the distribution of virulence genes, enterotoxin and biofilm formation among EAEC strains isolated from stools of children with diarrhea referred to three hospitals in south east Iran. Patients and Methods: A total of 464 diarrheic stools were screen for the presence of E. coli using conventional tests. Well isolated colonies were then evaluated for the presence of EAEC diagnostic genes (aggR and pCVD432) by duplex polymerase chain reaction (D-PCR). Positive samples were further subjected to three sets of multiplex-PCR for detection of fimbrial subunits (AAF), serine protease autotransporter toxins (SPATE) and at least one enterotoxin gene. Hemolytic activity was observed on sheep blood agar. Biofilm formation was measured by using a microtiter plate assay. Results: Among the 322 E. coli isolated, 23 were identified as EAEC. All EAEC carried a 630-bp fragment of the plasmid (pAA) encoded pCVD432 and aggR genes. Four major EAEC fimbriae variants aggA, agg4A, agg3A and aafA were detected, with the frequencies of 21.7% (n = 5), 26.8% (n = 6), 21.7% (n = 5) and 4.3% (n = 1), respectively. The class I and II virulence toxins pic, sat, sepA, pet and sigA were detected with frequencies of 56.5% (n = 13), 30.4% (n = 7), 26.8% (n = 6), 21.7% (n = 5) and 4.3% (n = 1), respectively. A heat-stable Shigella enterotoxin-1 gene (astA) was detected in 17.3% (n = 4) of the cases. In addition, 56.4% of the EAEC isolates were α-hemolytic. Quantification of the biofilm revealed six isolates with strong biofilm. Conclusions: Overall, except for pCVD432 and aggR, we detected high heterogeneity of virulence factors among EAEC isolates causing diarrhea in children. One set of genes, in the combination, pic- sepA- agg4A, was associated with strong biofilm.

Prevalence and virulence characteristics of enteroaggregative Escherichia coli in a case-control study among patients from Iran.

Enteroaggregative Escherichia coli (EAEC) is an important agent of diarrhoeal diseases worldwide. The role of EAEC virulence factors in the clinical outcome of infection is not completely defined. This case-control study investigated the prevalence of EAEC, its virulence genes and the antimicrobial resistance profile of adult patients with and without diarrhoea attending three different hospitals in Zanjan, Iran. A total of 550 individual stool specimens (350 from diarrhoeal patients and 200 from patients without diarrhoea) were collected. One hundred and forty-one EAEC isolates were identified by a HEp-2 cell assay and PCR. EAEC isolates were detected with slightly higher frequency in patients with (27.7%) than in patients without (22%) diarrhoea (P ≥ 0.05). The EAEC genes aggR, aap and pet were identified more frequently in case patients compared with controls (P ≤ 0.05). Many of the EAEC isolates from the diarrhoeal patients had two or more virulence genes compared with those without diarrhoea (P ≤ 0.05). EAEC isolates exhibited high-level resistance to amoxicillin (82.3%), co-amoxiclav (78%), aztreonam (73.8%), tetracycline (66.6%) and ceftazidime (63.8%). In addition, 53.2% of isolates were resistant to at least three different classes of antimicrobial agents and were considered to be multidrug resistant. These results indicate a high prevalence and heterogeneity of gene profiles of EAEC in diarrhoeal and control patients, and suggest that the presence of aggR, aap and pet, the number of genes present and the antimicrobial resistance profile may be markers for more-virulent EAEC isolates.

Involvement of main diarrheagenic Escherichia coli, with emphasis on enteroaggregative E. coli, in severe non-epidemic pediatric diarrhea in a high-income country.

BackgroundBacterial and viral enteric pathogens are the leading cause of diarrhea in infants and children. We aimed to identify and characterize the main human diarrheagenic E. coli (DEC) in stool samples obtained from children less than 5 years of age, hospitalized for acute gastroenteritis in Israel, and to examine the hypothesis that co-infection with DEC and other enteropathogens is associated with the severity of symptoms.MethodsStool specimens obtained from 307 patients were tested by multiplex PCR (mPCR) to identify enteroaggregative E. coli (EAEC), enterohemorrhagic (EHEC), enteropathogenic E. coli (EPEC) and enterotoxigenic E. coli (ETEC). Specimens were also examined for the presence of rotavirus by immunochromatography, and of Shigella, Salmonella and Campylobacter by stool culture; clinical information was also obtained.ResultsFifty nine (19%) children tested positive for DEC; EAEC and atypical EPEC were most common, each detected in 27 (46%), followed by ETEC (n = 3; 5%), EHEC and typical EPEC (each in 1 child; 1.5%). Most EAEC isolates were resistant to cephalexin, cefixime, cephalothin and ampicillin, and genotypic characterization of EAEC isolates by O-typing and pulsed-field gel electrophoresis showed possible clonal relatedness among some. The likelihood of having > 10 loose/watery stools on the most severe day of illness was significantly increased among patients with EAEC and rotavirus co-infection compared to children who tested negative for both pathogens: adjusted odds ratio 7.0 (95% CI 1.45-33.71, P = 0.015).ConclusionDEC was common in this pediatric population, in a high-income country, and mixed EAEC and rotavirus infection was characterized by especially severe diarrhea.

Frequency and Characterization of EPEC and EAggEC Isolated in Kawasaki City

Thirty isolates of enteropathogenic Escherichia coli (EPEC) and 32 isolates of enteroaggregative E. coli (EAggEC) were isolated from 1,029 stool samples collected from Spring 2012 to December 2013 in Kawasaki city with the polymerase chain reaction (PCR) method targeting eae and aggR genes. Among the 30 EPEC and 32 EAggEC isolates, only 9 strains of EPEC and 8 strains of EAggEC were typed with the commercial O-antisera, whereas the majority of strains were untypable. However, several O-untypable EPEC and EAggEC strains were suggested to harbor the same O-antigen because of the detection of several examples of the same H-antigen. Analysis of the HEp-2 cell adherence test showed positive for only 2 strains (6.6%) of 30 EPEC isolates, meanwhile it showed positive for 16 strains (50.0%) of 32 EAggEC isolates. From these data, we concluded that EAggEC might be more virulent than EPEC, although both EAggEC and EPEC were isolated with almost similar rates from collected stool specimens.

Characterization and biofilm forming ability of diarrhoeagenic enteroaggregative Escherichia coli isolates recovered from human infants and young animals.

Enteroaggregative Escherichia coli (EAEC) is an important pathotype that causes infection in humans and animals. EAEC isolates (n=86) recovered from diarrhoeal cases in human infants (37) and young animals (49) were characterized as 'typical' and/or 'atypical' EAEC strains employing PCR for virulence associated genes (cvd432, aaiA, astA, pilS, irp2, ecp, pic, aggR, aafA, aggA, and agg3A). Besides, biofilm formation ability of human and animal EAEC isolates was assessed using microtiter plate assay. In addition, the transcriptional profile of biofilm associated genes (fis and ecp) was also evaluated and correlated with biofilm formation assay for few selected EAEC isolates of human and animal origins. Overall, a diverse virulence gene profile was observed for the EAEC isolates of human and animal origins as none of the EAEC isolates revealed the presence of all the genes that were targeted. Nine 'typical' EAEC isolates were identified (6 from humans and 3 from animals) while, the majority of the isolates were 'atypical' EAEC strains. Isolation and identification of three 'typical' EAEC isolates from animals (canines) appears to be the first report globally. Further, based on the observations of the biofilm formation assay, the study suggested that human EAEC isolates in particular were comparatively more biofilm producers than that of the animal EAEC isolates. The fis gene was highly expressed in majority of 'typical' EAEC isolates and the ecp gene in 'atypical' EAEC isolates.

Enteroaggregative Escherichia coli have evolved independently as distinct complexes within the E. coli population with varying ability to cause disease.

Enteroaggregative E. coli (EAEC) is an established diarrhoeagenic pathotype. The association with virulence gene content and ability to cause disease has been studied but little is known about the population structure of EAEC and how this pathotype evolved. Analysis by Multi Locus Sequence Typing of 564 EAEC isolates from cases and controls in Bangladesh, Nigeria and the UK spanning the past 29 years, revealed multiple successful lineages of EAEC. The population structure of EAEC indicates some clusters are statistically associated with disease or carriage, further highlighting the heterogeneous nature of this group of organisms. Different clusters have evolved independently as a result of both mutational and recombination events; the EAEC phenotype is distributed throughout the population of E. coli.

An investigation of the diversity of strains of enteroaggregative Escherichia coli isolated from cases associated with a large multi-pathogen foodborne outbreak in the UK.

Following a large outbreak of foodborne gastrointestinal (GI) disease, a multiplex PCR approach was used retrospectively to investigate faecal specimens from 88 of the 413 reported cases. Gene targets from a range of bacterial GI pathogens were detected, including Salmonella species, Shigella species and Shiga toxin-producing Escherichia coli, with the majority (75%) of faecal specimens being PCR positive for aggR associated with the Enteroaggregative E. coli (EAEC) group. The 20 isolates of EAEC recovered from the outbreak specimens exhibited a range of serotypes, the most frequent being O104:H4 and O131:H27. None of the EAEC isolates had the Shiga toxin (stx) genes. Multilocus sequence typing and single nucleotide polymorphism analysis of the core genome confirmed the diverse phylogeny of the strains. The analysis also revealed a close phylogenetic relationship between the EAEC O104:H4 strains in this outbreak and the strain of E. coli O104:H4 associated with a large outbreak of haemolytic ureamic syndrome in Germany in 2011. Further analysis of the EAEC plasmids, encoding the key enteroaggregative virulence genes, showed diversity with respect to FIB/FII type, gene content and genomic architecture. Known EAEC virulence genes, such as aggR, aat and aap, were present in all but one of the strains. A variety of fimbrial genes were observed, including genes encoding all five known fimbrial types, AAF/1 to AAF/V. The AAI operon was present in its entirety in 15 of the EAEC strains, absent in three and present, but incomplete, in two isolates. EAEC is known to be a diverse pathotype and this study demonstrates that a high level of diversity in strains recovered from cases associated with a single outbreak. Although the EAEC in this study did not carry the stx genes, this outbreak provides further evidence of the pathogenic potential of the EAEC O104:H4 serotype.

Enteroaggregative Escherichia coli in diarrheic children in Egypt: molecular characterization and antimicrobial susceptibility.

Little information is available regarding the significance of enteroaggregative Escherichia coli (EAEC) in pediatric diarrhea in Egypt. Escherichia coli was isolated from stool samples of 62 diarrheic and 43 non-diarrheic (control) Egyptian children. Samples were screened for genes specific for enteroaggregative E. coli (EAEC), enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC), Shiga toxin-producing E. coli (STEC), and enteroinvasive E. coli (EIEC) using polymerase chain reaction (PCR). Diarrheagenic E. coli were grouped phylogenetically using PCR and tested for their susceptibility to antibiotics using the disk diffusion method. Isolates designated as EAEC were examined for eight virulence factors (VFs) using PCR. EAEC was detected in 19 (30.7%) and 4 (9.3%), EPEC in 2 (3.2%) and 1 (2.3%), and ETEC in 2 (3.2%) and 0 (0.0%) diarrheic and control children, respectively; STEC and EIEC were not detected. Only EAEC was significantly isolated from diarrheic children compared with controls (p < 0.01, OR = 4.31).Three or more VFs (multivirulent isolates) were found in 52.6% and 50% of EAEC isolated from diarrheic children and controls, respectively. More than 73% (17/23) of EAEC isolates were identified as belonging to phylogenetic group D. Multiple-antibiotic resistance (resistance to three or more drugs) was observed in more than 91% of EAEC. Multivirulent EAEC is a significant causative agent of pediatric diarrhea in Egypt, with the majority of isolated EAEC belong to phylogenetic group D. Multiple-antibiotic resistance among EAEC has the potential to be a serious public health problem for the country.

Enteroaggregative Escherichia Coli (EAEC) in South of Iran

Introduction: The aim of the present study was to investigate the presence and the frequency of EAEC as etiologic agent of diarrhea in Shiraz. Enteroaggregative E. coli (EAEC) is increasingly recognized as a cause of often persistent diarrhoea in children and adults in both developing and developed countries, and have been identified as the cause of several outbreaks worldwide. Materials and Method: A total of 715 stool samples were collected from patients with diarrhea in Shiraz. Diarrheagenic E. coli were isolated by biochemical tests and culture from 715 stool samples collected from different hospitals. Diarrheagenic E. coli strains isolated from diarrheal stool samples were examined for the detection of the aggR gene by Real time PCR and PCR method. Results: In this study, a total of 101 (14.12%) diarrheagenic E. coli were isolated from 715 stool samples collected from different hospitals. Diarrheagenic E. coli were isolated much more frequently in the summer months than other season. Out of these 101 diarrheagenic E. coli identified, 5 were confirmed as EAEC in patient. The high prevalence of EAEC isolates was also found in watery diarrhea. Conclusion: We therefore, recommend the routine isolation and identification of EAEC strains from patient with diarrhea in all the clinical laboratories and other pathotype diarrhoeagenic E. coli in Iran. Keywords: Diarrhea, Enteroaggregative Escherichia coli (EAEC), Real-Time PCR.

Extended spectrum betalactamase producing Enteroaggregative Escherichia coli from young children in Iran.

The aim of this study was to investigate the frequency of betalactamase producing EAEC isolates among young children with diarrhea in Zanjan, Iran. Entero aggregative Escherichia coli (EAEC) is an emerging enteric pathogen associated with acute and persistent diarrhea and the evolution and spread of acquired extended spectrum betalactamases (ESBLs) among these strains has become a serious problem in the management of infectious diseases in developing countries. During the period from March 2011 to January 2012, 140 isolates of E. coli from diarrheal children aged 0-60 months and 90 isolates from age-matched controls without diarrhea were investigated for EAEC using PCR. Antimicrobial susceptibility testing was performed as CLSI guidelines and betalactamase genes, including bla TEM, bla CTX-M, bla IMP, bla VIM and bla NDM-1 investigated in EAEC isolates. In this study, EAEC was detected with slightly higher frequency in children with (8%) than in children without (4.6%) diarrhea (P > 0.05). Diarrheagenic E. coli exhibited high level resistance to aztreonam (80.7%), amoxicillin (74.4%) and tetracycline (69.3%). Also, 86.4% of E. coli isolates were resistant to at least three different classes of antimicrobial agents and considered as multidrug resistance. Molecular characterization of betalactamase genes showed that bla TEM was the most frequently isolated betalactamase. It was detected in 78.9% of ESBL producing EAEC isolates. Also, the frequency of bla CTX-M was 63.1% (12/19) and 8 (42.1%) isolates carried the bla TEM and bla CTX-M, simultaneously. None MBL producing EAEC was detected in our study. Our results indicate that ESBLs especially bla TEM and bla CTX-M are widespread among EAEC isolates and appropriate surveillance and control measures are essential to prevent further dissemination of betalactamases in our country.

Frequency and Antimicrobial Susceptibility of Diarrheagenic Escherichia coli Obtained from Patients with Acute Diarrhea in a Tertiary Care Hospital, Bangladesh

Escherichia coli (E. coli) is an important group of pathogens associated with diarrhea among children. Despite the fact that diarrhaegenic Escherichia coli (DEC) has been identified as a major etiologic agent of childhood diarrhea, only a few studies have been performed in Bangladesh to identify these organisms. The objective of this study was to determine the frequency and antimicrobial susceptibility of DEC obtained from patients with acute diarrhea. To detect DEC in patients with acute diarrhea, a total of 300 stool specimens were tested by multiplex polymerase chain reaction (PCR). The antimicrobial susceptibility of DEC were tested by Kirby-Bauer disc diffusion technique as per recommendation of CLSI (Clinical and Laboratory Standards Institute), 2010. Out of 300 stool specimens collected from patients with acute diarrhea, the DEC was detected in 18% (54/300) cases. The dominating strain was Enterotoxigenic E. coli ( ETEC) (13%, 39/300), followed by Enteroaggregative E. coli (EAEC) (5%, 15/300) and no Enterohemorrhagic E. coli (EHEC), Enteroinvasive E. coli ( EIEC) and Enteropathogenic E. coli ( EPEC) could be detected. Detected ETEC were 100% sensitive to Ceftriaxone, Nitrofurantioin, Amikacin, 94% sensitive to Nalidixic acid, 89% sensitive to Gentamycin, 83% sensitive to Ciprofloxacin, 79% sensitive to Cephalexin, 39% sensitive to Amoxycillin, 46% sensitive to Tetracyclin and 31% sensitive to Cotrimoxazole. Detected EAEC were 100% sensitive to Ceftriaxone, Nitrofurantioin, Amikacin, Nalidixic acid, 90% sensitive to Gentamycin and Ciprofloxacin, 85% sensitive to Cephalexin, 41% sensitive to Amoxycillin, 49% sensitive to Tetracycline and 31% sensitive to Cotrimoxazole. Both ETEC and EAEC isolates exhibited decreased susceptibility for Amoxycillin, Tetracycline and Cotrimoxazole. Our results revealed that ETEC and EAEC, had significant association with acute diarrhea and should be considered as potential pathogens. Guidelines for appropriate use of antibiotics in tertiary care hospitals need updating. DOI: http://dx.doi.org/10.3329/cbmj.v2i2.16698 Community Based Medical Journal 2013 July: Vol.02 No 02: 46-51