Elsevier

Journal of Infection

Volume 64, Issue 4, April 2012, Pages 387-390
Journal of Infection

Risk of secondary cases of Clostridium difficile infection among household contacts of index cases

https://doi.org/10.1016/j.jinf.2011.12.011Get rights and content

Summary

Objectives

We aimed to estimate the risk of secondary cases of Clostridium difficile infection (CDI) among household contacts of index cases.

Methods

We reviewed all 2222 patients with confirmed CDI in a region of Quebec, Canada, during 1998–2009. Our laboratory serves a well-defined population for which it is the sole centre providing CDI testing, enabling us to calculate accurate population annual incidence rates of CDI. Cases with the same phone number were verified individually to determine whether they were indeed related. We considered as related two cases occurring in the same household within one year of each other.

Results

We estimated that 1061 spouses and 501 children (<25 years-old) lived in the same household as the index cases, of which respectively 5 and 3 developed CDI. Among spouses and children, the attack rate was 4.71/1000 and 5.99/1000 respectively, and the relative risk was 7.61 (95%CI: 5.77–9.78) and 90.6 (95%CI: 33.89–487.64) for the three months after the diagnosis in the index case.

Conclusions

Although the relative risk of CDI among household contacts is somewhat increased for a few months, the absolute risk is too low to justify interventions, apart from avoiding unnecessary courses of antimicrobials.

Introduction

In many industrialized countries, the incidence of Clostridium difficile infection (CDI) has escalated during the last decade.1, 2, 3 This coincided with the emergence of a toxin-hyper-producing strain (BI/NAP1/027), which seems to be more transmissible than other strains within hospital environments, especially in older patients.4 Albeit CDI is classically a nosocomial disease, the incidence of community-acquired CDI also seems to be increasing, representing between 11% and 28% of the cases.5 Little is known about the risk of secondary cases among household contacts of index cases, whether the index case had acquired CDI at the hospital or in the community. To estimate the risk of secondary cases developing outside hospitals by identifying cases that were related to each other, we conducted a retrospective survey of CDI in a well-defined population of Canada, where the BI/NAP1/027 strain emerged in 2002.

Section snippets

Database of Clostridium difficile infections

We included all patients with CDI diagnosed at the Centre Hospitalier Universitaire de Sherbrooke, in the province of Quebec, Canada, from January 1st 1998 to December 31st 2009, and who lived in the Estrie region (population in 2009: 307,252).2 Most CDI patients were identified through a review of the reports of a positive C. difficile cytotoxicity assay in the computerized hospital database, while a few patients, diagnosed solely by endoscopy or pathology, were identified through reviewing

Results

Table 1 displays the nine clusters that were identified. There were five couples in which both spouses developed CDI within a year of each other and four clusters in which a parent and child developed CDI within the same interval. One of the latter clusters will not be considered further, as it involved an 85-year-old man living with his 60-year-old daughter. All but one of these secondary cases occurred within two months of the index case. During the study period, no secondary cases of CDI

Discussion

This study is the first exploring this component of the epidemiology of CDI. CDI person-to-person transmission in the community has been described in a small number of case-reports9, 10, 11 but this has never been quantified systematically.

Albeit we identified a substantial short-term increase in the relative risk amongst household contacts of CDI patients, this translated into a very modest absolute risk, with attack rates of 4.71 per 1000 for spouses and 5.99 per 1000 for children of index

Financial support

This study was supported by departmental funding.

Study design and manuscript preparation

All authors were involved in data analysis as well as manuscript preparation.

Conflict of interest

Dr Pepin has served on advisory boards for Pfizer, Wyeth, Ortho, Merck, Acambis, Iroko and The Medicines Company. Dr Valiquette has served on advisory boards for Oryx, Iroko, Abbott and Wyeth, and has received compensation to conduct clinical trials involving antibacterials from Genzyme, Wyeth, Pfizer, BioCryst, Trius, Cempra, Optimer and Arpida. M. Gonzales Fuentes has no competing interest to report.

Acknowledgement

None.

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