Genetic Virulence Profile of Enteroaggregative Escherichia coli Strains Isolated from Danish Children with Either Acute or Persistent Diarrhea

Abstract

Enteroaggregative Escherichia coli (EAEC) is frequently found in diarrheal stools worldwide. It has been associated with persistent diarrhea, weight loss, and failure to thrive in children living in developing countries. A number of important EAEC virulence genes are identified; however, their roles in acute and persistent diarrhea have not been previously investigated. The aim of this study was to identify specific EAEC virulence genes associated with duration and type of diarrhea in Danish children. We aimed to improve the current diagnostics of EAEC and enable targeting of strains with an expected severe disease course. Questionnaires answered by parents provided information regarding duration of diarrhea and presence of blood or mucus. A total of 295 EAEC strains were collected from children with acute (≤7 days) and persistent diarrhea (≥14 days) and were compared by using multiplex PCR targeting the genes sat, sepA, pic, sigA, pet, astA, aatA, aggR, aaiC, aap, agg3/4C, ORF3, aafA, aggA, agg3A, agg4A, and agg5A. Furthermore, the distribution of EAEC genes in strains collected from cases of bloody, mucoid, and watery diarrhea was investigated. The classification and regression tree analysis (CART) was applied to investigate the relationship between EAEC virulence genes and diarrheal duration and type. Persistent diarrhea was associated with strains lacking the pic gene (p = 0.002) and with the combination of the genes pic, sat, and absence of the aggA gene (p = 0.05). Prolonged diarrhea was associated with the combination of the genes aatA and astA (p = 0.03). Non-mucoid diarrhea was associated with strains lacking the aatA gene (p = 0.004). Acute diarrhea was associated with the genes aggR, aap, and aggA by individual odds ratios. Resistance toward gentamicin and ciprofloxacin was observed in 7.5 and 3% of strains, respectively. Multi-drug resistance was observed in 38% of strains. Genetic host factors have been associated with an increased risk of EAEC-associated disease. Therefore, we investigated a panel of risk factors in two groups of children—EAEC-positive and EAEC-negative—to identify additional factors predisposing to disease. The duration of breastfeeding was positively correlated with the likelihood of belonging to the EAEC-negative group of children.

Characterization of Diarrheagenic Enteroaggregative Escherichia coli in Danish Adults—Antibiotic Treatment Does Not Reduce Duration of Diarrhea

“…We detected high levels of antibiotic resistance among 137 EAEC strains isolated from Danish adults suffering from diarrhea. Previously, we have detected MDR among 35% of EAEC strains in Danish children in daycare (Hebbelstrup Jensen et al, 2016 ), and in 38% of EAEC strains isolated from Danish children with diarrhea (Hebbelstrup Jensen et al, 2017 ). Surprisingly, in this study, we detected a high level of resistance toward ciprofloxacin (34%), which is still one of the most frequently used antimicrobials for diarrhea (Kong et al, 2015 ).…”

“…The astA gene encodes the enterotoxin EAST-1, which is commonly detected in EAEC strains, and has previously been associated with watery diarrhea (Ménard and Daniel Dubreuil, 2002 ; Kaper et al, 2004 ). Previously, we have described how the astA is important in prolonged diarrhea in children (Hebbelstrup Jensen et al, 2017 ). However, many commensal E. coli strains also harbor the EAST-1 toxin, and it has, therefore, been suggested that additional virulence factors are required to mediate diarrhea (Konno et al, 2012 ).…”

Control of Growth and Persistence of Listeria monocytogenes and β-Lactam-Resistant Escherichia coli by Thymol in Food Processing Settings

“…The aatA gene is a key gene in enteroaggregative E. coli (EAEC) and it encodes part of the outer membrane transport system (ABC transporter) involved in the translocation of the dispersin protein. The aatA and astA genes are associated with prolonged diarrhea in EAEC strains [21]. Three different phylogenetic groups were detected, although all isolates came from the same farm.…”

High Genomic Diversity and Heterogenous Origins of Pathogenic and Antibiotic-Resistant Escherichia coli in Household Settings Represent a Challenge to Reducing Transmission in Low-Income Settings

“…2). Notably, nine phylogenetically diverse E. coli (median, 37,617 SNPs), including three soil isolates (HH25S, HH26S, and HH51S), coharbored aatA and astA (the simultaneous presence of aatA and astA has been associated with prolonged diarrhea [47]), highlighting the diversity of pathogenic E. coli circulating in these rural Bangladeshi communities. The presence of astA in the absence of additional pathogenic markers, as observed in eight E. coli isolates, lacks the discriminatory power to assign these strains within any of the intestinal pathotypes, as astA has been associated with multiple intestinal pathotypes (48)(49)(50) and is also prevalent in extraintestinal (51), commensal (50), and environmental isolates (52).…”