Mixture model to assess the extent of cross-transmission of multidrug-resistant pathogens in hospitals.
OBJECTIVE
Creation of a mixture model based on Poisson processes for assessment of the extent of cross-transmission of multidrug-resistant pathogens in the hospital.


METHODS
We propose a 2-component mixture of Poisson processes to describe the time series of detected cases of colonization. The first component describes the admission process of patients with colonization, and the second describes the cross-transmission. The data set used to illustrate the method consists of the routinely collected records for methicillin-resistant Staphylococcus aureus (MRSA), imipenem-resistant Pseudomonas aeruginosa, and multidrug-resistant Acinetobacter baumannii over a period of 3 years in a German tertiary care hospital.


RESULTS
For MRSA and multidrug-resistant A. baumannii, cross-transmission was estimated to be responsible for more than 80% of cases; for imipenem-resistant P. aeruginosa, cross-transmission was estimated to be responsible for 59% of cases. For new cases observed within a window of less than 28 days for MRSA and multidrug-resistant A. baumannii or 40 days for imipenem-resistant P. aeruginosa, there was a 50% or greater probability that the cause was cross-transmission.


CONCLUSIONS
The proposed method offers a solution to assessing of the extent of cross-transmission, which can be of clinical use. The method can be applied using freely available software (the package FlexMix in R) and it requires relatively little data.
Mikolajczyk
Rafael T
RT
University of Bielefeld, Germany. rmikolajczyk@uni-bielefeld.de
Kauermann
Göran
G
Sagel
Ulrich
U
Kretzschmar
Mirjam
M
D000151:Acinetobacter Infections / Q000453:epidemiology / Q000382:microbiology / Q000635:transmission; D040981:Acinetobacter baumannii / Q000187:drug effects; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001424:Bacterial Infections / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission*; D003428:Cross Infection / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission*; D004197:Disease Reservoirs; D024881:Drug Resistance, Bacterial; D024901:Drug Resistance, Multiple, Bacterial; D006801:Humans; D015378:Imipenem / Q000494:pharmacology; D017053:Infection Control; D055624:Methicillin-Resistant Staphylococcus aureus; D008826:Microbial Sensitivity Tests; D016012:Poisson Distribution; D011336:Probability; D011552:Pseudomonas Infections / Q000453:epidemiology / Q000382:microbiology / Q000635:transmission; D011550:Pseudomonas aeruginosa / Q000187:drug effects; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology / Q000635:transmission; D013997:Time Factors
D000900:Anti-Bacterial Agents; D015378:Imipenem