Importance of case age in the purported association between phylogenetics and hemolytic uremic syndrome in Escherichia coli O157:H7 infections.

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.

Cervical squamous intraepithelial lesions and associated cervical infections in an HIV-positive population in Rural Mpumalanga, South Africa.

BACKGROUND: The incidences of genital human papillomavirus (HPV) infection, associated squamous intraepithelial lesions and cervical squamous cell carcinoma are significantly increased in HIV-positive women. The role of other cervicovaginal infections in the acquisition of the HPV infection, cervical carcinogenesis and genital HIV infection remains largely speculative. METHODS: A retrospective study was conducted including 1087 HIV-positive women in rural Mpumalanga province, South Africa, for the period 1 May 2009 to 31 August 2010. For each patient, the age at first presentation, cervical cytological diagnosis, subsequent follow-up cytology and histology, and microscopically visible infections (including endemic Bilharzia) were tabulated and statistically analysed. RESULTS: The prevalence of low-grade squamous intraepithelial lesion (LSIL), high-grade squamous intraepithelial lesion (HSIL), squamous cell carcinoma, atypical squamous cells of undetermined significance (ASC-US) and atypical squamous cells, cannot exclude HSIL (ASC-H) in the study population were 22.1%, 30.9%, 0.6%, 13.5% and 4.0%, respectively. LSIL, HSIL and squamous cell carcinoma were diagnosed, respectively, at the average ages of 35.7, 37.9 and 37.2 years. Four patients with cervical intraepithelial neoplasia grade 1 (CIN1), 32 with CIN2/CIN3 and two with cervical squamous cell carcinoma were also diagnosed with Bilharzia. Of the other infections only bacterial vaginosis had a positive statistical correlation with HPV-induced cervical abnormalities (LSIL, HSIL or squamous cell carcinoma). CONCLUSION: This study confirms the high prevalence of progressive HPV-associated cervical disease in a rural Southern African HIV-positive population, which is at least equal to or worse than in other African HIV-positive studies. The high incidence of Bilharzia infection in those cases that underwent cervical cone excision suggests a possible relationship with progressive HPV disease and cervical carcinogenesis. Bacterial vaginosis (perhaps in combination with Bilharzia) may compromise the normal barriers against HPV and HIV infection.