American Journal of Epidemiology Advance Access originally published online on July 21, 2007
American Journal of Epidemiology 2007 166(7):841-851; doi:10.1093/aje/kwm149
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
PRACTICE OF EPIDEMIOLOGY |
An Algorithm to Estimate the Importance of Bacterial Acquisition Routes in Hospital Settings
1 Department of Mathematics, Utrecht University, Utrecht, Kingdom of the Netherlands
2 Department of Internal Medicine and Dermatology, University Medical Center Utrecht, Utrecht, Kingdom of the Netherlands
3 Eijkman Winkler Institute for Microbiology, Infectious Diseases, and Inflammation, University Medical Center Utrecht, Utrecht, Kingdom of the Netherlands
4 Julius Center for Health Research and Primary Care, University Medical Center Utrecht, Utrecht, Kingdom of the Netherlands
Correspondence to Dr. Martin Bootsma, Mathematical Institute, Utrecht University, Budapestlaan 6, 3508 TA Utrecht, Kingdom of the Netherlands (e-mail: bootsma{at}math.uu.nl).
Received for publication December 4, 2006. Accepted for publication April 4, 2007.
An algorithm is presented to calculate likelihoods of acquisition routes using only individual patient data concerning period of stay and microbiologic surveillance (without genotyping). The algorithm also produces estimates for the prevalence and the number of acquisitions by each route. The algorithm is applied to colonization data of third-generation cephalosporin-resistant Enterobacteriaceae (CRE) from September 2001 to May 2002 in two intensive care units (ICUs) (n = 277 and n = 180, respectively) of Utrecht, Kingdom of the Netherlands. Genotyping and epidemiologic linkage are used as the reference standard. Surveillance cultures were obtained on admission and twice weekly thereafter. All CREs were genotyped. According to the reference standard, the daily prevalence of CRE in ICU-1 and ICU-2 was 26.1% (standard deviation: 15.4) and 15.1% (standard deviation: 13.4), respectively, with five of 23 (21.7%) and six of 21 (28.6%) cases of acquired colonization being of exogenous origin, respectively. On the basis of the algorithm, the endogenous route was responsible for more acquisitions than the exogenous route (p = 0.003 and p < 0.001 for ICU-1 and ICU-2, respectively). The estimated number of acquisitions is 30 and 27, and the estimated prevalence is 27.6% and 17.6% for ICU-1 and ICU-2, respectively. By use of longitudinal colonization data only, the algorithm determines the relative importance of acquisition routes taking patient dependency into account.
algorithms; disease transmission; Enterobacteriaceae; maximum likelihood; parameters; small population
Abbreviations: AFLP, amplified fragment-length polymorphism; CRE, cephalosporin-resistant Enterobacteriaceae; ICU(s), intensive care unit(s); MLE, maximum likelihood estimate; SD, standard deviation
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  B. S. Cooper, G. F. Medley, S. J. Bradley, and G. M. Scott An Augmented Data Method for the Analysis of Nosocomial Infection Data Am. J. Epidemiol., September 1, 2008; 168(5): 548 - 557. [Abstract] [Full Text] [PDF]
|
|