ABSTRACT
Enteroaggregative Escherichia coli (EAEC), a highly heterogeneous pathotype of E. coli classified as typical and atypical, are an emerging cause of acute and persistent diarrhea. We aimed to investigate whether population living in rural geographic areas, impacts in the heterogeneity, dissemination and antimicrobial susceptibility of EAEC strains. EAEC isolates (n=73) were analysed for the presence of 23 putative virulence factors, plasmid and antimicrobial resistance profiles, biofilm formation, pulsedfield gel electrophoresis (PFGE) and by multilocus sequence typing (MLST). The agg3A, agg4A, agn43, aap, shf, astA, pet, pic/set1A and sat genes, biofilm forming and antimicrobial resistance were statistically associated with typical EAEC. A low frequency of all isolates was resistant or showed a multidrug-resistance profile. No isolate showed the same plasmid profile. In total, 58 different pulsotypes were observed. Sixteen isolates analysed by MLST belonged to 15 different sequence types (ST) and showed a different PFGE pattern and virulence-gene profile. The fact that the communities are semi-isolated did not impact on the peculiar heterogeneity of EAEC, being characterized as epidemiologically independent strains.
Subject(s)
Diarrhea/epidemiology , Diarrhea/microbiology , Escherichia coli Infections/epidemiology , Escherichia coli Infections/microbiology , Escherichia coli/classification , Escherichia coli/genetics , Genetic Heterogeneity , Child , Child, Preschool , Female , Humans , Infant , Infant, Newborn , Male , Microbial Sensitivity Tests , Multilocus Sequence Typing , Plasmids/analysis , Rural PopulationABSTRACT
BACKGROUND: Diarrheagenic Escherichia coli (DEC) are important bacterial causes of childhood diarrhea in Brazil, but its impact in adults is unknown. This study aimed at investigating DEC among children and adults living in endemic areas. METHODS: A total of 327 stools specimens were collected from children (n = 141) and adults (n = 186) with diarrhea attending health centers. Diarrheagenic E. coli (DEC) were identified by their virulence genes (multiplex polymerase chain reaction) and HEp-2 cell adherence patterns. RESULTS: DEC were detected in 56 (40%) children and 74 (39%) adults; enteroaggregative E. coli (EAEC) (23%) was the most prevalent pathotype, followed by diffusely adherent E. coli (DAEC) (13%), and occurred at similar frequencies in both diarrheal groups. Atypical enteropathogenic E. coli (aEPEC) strains were recovered more frequently from children (6%) than from adults (1%). Twenty-six percent of the EAEC were classified as typical EAEC possessing aggR gene, and carried the aap gene. EAEC strains carrying aggR-aap-aatA genes were significantly more frequent among children than adults (p < 0.05). DAEC strains possessing Afa/Dr. genes were detected from children (10%) and adults (6%). EAEC and DAEC strains harboring genes for the EAST1 (astA), Pet, Pic, and Sat toxins were common in both diarrheal groups. The astA and the porcine AE/associated adhesin (paa) genes were found in most of aEPEC strains. High levels of resistance to antimicrobial drugs were found among DAEC and aEPEC isolates. CONCLUSION: The results show a high proportion of EAEC and DAEC carrying toxin-encoding genes among adults with diarrhea.