TY - JOUR
T1 - Importance of case age in the purported association between phylogenetics and hemolytic uremic syndrome in Escherichia coli O157:H7 infections
AU - Tarr, G. A.M.
AU - Shringi, S.
AU - Oltean, H. N.
AU - Mayer, J.
AU - Rabinowitz, P.
AU - Wakefield, J.
AU - Tarr, P. I.
AU - Besser, T. E.
AU - Phipps, A. I.
N1 - Publisher Copyright:
Copyright © Cambridge University Press 2018.
PY - 2018/9/1
Y1 - 2018/9/1
N2 - Escherichia coli O157:H7 is the largest cause of hemolytic uremic syndrome (HUS). Previous studies proposed that HUS risk varies across the E. coli O157:H7 phylogenetic tree (hypervirulent clade 8), but the role of age in the association is unknown. We determined phylogenetic lineage of E. coli O157:H7 isolates from 1160 culture-confirmed E. coli O157:H7 cases reported in Washington State, 2004-2015. Using generalised estimating equations, we tested the association between phylogenetic lineage and HUS. Age was evaluated as an effect modifier. Among 1082 E. coli O157:H7 cases with both phylogenetic lineage and HUS status (HUS n = 76), stratified analysis suggested effect modification by age. Lineages IIa and IIb, relative to Ib, did not appear associated with HUS in children 0-9-years-old. For cases 10-59-years-old, lineages IIa and IIb appeared to confer increased risk of HUS, relative to lineage Ib. The association reversed in ≥60-year-olds. Results were similar for clade 8. Phylogenetic lineage appears to be associated with HUS risk only among those ≥10-years-old. Among children <10, the age group most frequently affected, lineage does not explain progression to HUS. However, lineage frequency varied across age groups, suggesting differences in exposure and/or early disease manifestation.
AB - Escherichia coli O157:H7 is the largest cause of hemolytic uremic syndrome (HUS). Previous studies proposed that HUS risk varies across the E. coli O157:H7 phylogenetic tree (hypervirulent clade 8), but the role of age in the association is unknown. We determined phylogenetic lineage of E. coli O157:H7 isolates from 1160 culture-confirmed E. coli O157:H7 cases reported in Washington State, 2004-2015. Using generalised estimating equations, we tested the association between phylogenetic lineage and HUS. Age was evaluated as an effect modifier. Among 1082 E. coli O157:H7 cases with both phylogenetic lineage and HUS status (HUS n = 76), stratified analysis suggested effect modification by age. Lineages IIa and IIb, relative to Ib, did not appear associated with HUS in children 0-9-years-old. For cases 10-59-years-old, lineages IIa and IIb appeared to confer increased risk of HUS, relative to lineage Ib. The association reversed in ≥60-year-olds. Results were similar for clade 8. Phylogenetic lineage appears to be associated with HUS risk only among those ≥10-years-old. Among children <10, the age group most frequently affected, lineage does not explain progression to HUS. However, lineage frequency varied across age groups, suggesting differences in exposure and/or early disease manifestation.
KW - Epidemiology
KW - Escherichia coli (E. coli)
KW - Shiga toxin-producing E. coli
KW - phylogenetics
UR - http://www.scopus.com/inward/record.url?scp=85048770022&partnerID=8YFLogxK
U2 - 10.1017/S0950268818001632
DO - 10.1017/S0950268818001632
M3 - Article
C2 - 29914582
AN - SCOPUS:85048770022
SN - 0950-2688
VL - 146
SP - 1550
EP - 1555
JO - Epidemiology and infection
JF - Epidemiology and infection
IS - 12
ER -