A mathematical model quantifying the impact of antibiotic exposure and other interventions on the endemic prevalence of vancomycin-resistant enterococci.
BACKGROUND
Mathematical modeling can be used to describe the interdependent and dynamic interactions that contribute to the transmission dynamics of vancomycin-resistant enterococci (VRE). A model was developed to quantify the contribution of antibiotic exposure and of other modifiable factors to the dissemination of VRE in the hospital setting.


METHODS
The model consists of 4 compartments: patients colonized with VRE receiving and not receiving antibiotics and uncolonized patients receiving and not receiving antibiotics. A series of differential equations describe the movement between these compartments. Baseline parameter estimates were obtained from pharmacy, infection-control, and clinical databases.


RESULTS
The main predictions of this model are that (1) preventing the initiation or enhancing the discontinuation of unnecessary antimicrobial therapy will have a greater impact if it is targeted to patients who are not colonized with VRE; (2) increasing the number of patients harboring VRE at the time of hospital admission substantially increases the endemic prevalence of VRE; and (3) eliminating the influx of VRE results in the eradication of this pathogen from the hospital. A decrease in the endemic prevalence of VRE also occurs with a decrease in the length of hospital stay of colonized patients, increased hand hygiene compliance, and a lower ratio of health-care workers : patients.


CONCLUSIONS
This mathematical model provides a framework to assist in targeting necessary interventions aimed at limiting the spread of VRE.
D'Agata
Erika M C
EM
Division of Infectious Diseases, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA. edagata@bidmc.harvard.edu
Webb
Glenn
G
Horn
Maryann
M
D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D024881:Drug Resistance, Bacterial; D019353:Endemic Diseases; D016983:Enterococcus / Q000187:drug effects*; D016908:Gram-Positive Bacterial Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission; D006760:Hospitalization; D006801:Humans; D007902:Length of Stay; D008954:Models, Biological; D015995:Prevalence; D020713:Vancomycin Resistance
D000900:Anti-Bacterial Agents