How to assess the relative importance of different colonization routes of pathogens within hospital settings

The emergence of antibiotic resistance among nosocomial pathogens has reemphasized the need for effective infection control strategies. The spread of resistant pathogens within hospital settings proceeds along various routes of transmission and is characterized by large fluctuations in prevalence, which are typical for small populations. Identification of the most important route of colonization (exogenous by cross-transmission or endogenous caused by the selective pressure of antibiotics) is important for the design of optimal infection control strategies. Such identification can be based on a combination of epidemiological surveillance and costly and laborious as well as time-consuming methods of genotyping. Furthermore, analysis of the effects of interventions is hampered by the natural fluctuations in prevalence. To overcome these problems, we introduce a mathematical algorithm based on a Markov chain description. The input is longitudinal prevalence data only. The output is estimates of the key parameters characterizing the two colonization routes. The algorithm is tested on two longitudinal surveillance data sets of intensive care patients. The quality of the estimates is determined by comparing them to accurate estimates based on additional information obtained by genotyping. The results warrant optimism that this algorithm may help to quantify transmission dynamics and can be used to evaluate the effects of infection control interventions more carefully.

[1]  R. May,et al.  Infectious Diseases of Humans: Dynamics and Control , 1991, Annals of Internal Medicine.

[2]  Mitchell L. Cohen Epidemiology of Drug Resistance: Implications for a Post—Antimicrobial Era , 1992, Science.

[3]  D H Persing,et al.  Interpreting chromosomal DNA restriction patterns produced by pulsed-field gel electrophoresis: criteria for bacterial strain typing , 1995, Journal of clinical microbiology.

[4]  J. Vincent,et al.  The prevalence of nosocomial infection in intensive care units in Europe. Results of the European Prevalence of Infection in Intensive Care (EPIC) Study. EPIC International Advisory Committee. , 1995, JAMA.

[5]  R A Weinstein,et al.  A Comparison of the Effect of Universal Use of Gloves and Gowns with That of Glove Use Alone on Acquisition of Vancomycin-Resistant Enterococci in a Medical Intensive Care Unit , 1996, Annals of Internal Medicine.

[6]  Y. Fukuchi,et al.  Dissemination in Japanese hospitals of strains of Staphylococcus aureus heterogeneously resistant to vancomycin , 1997, The Lancet.

[7]  Sylvie Chevret,et al.  Modeling the spread of resistant nosocomial pathogens in an intensive-care unit. , 1997 .

[8]  A. Ambergen,et al.  The role of "colonization pressure" in the spread of vancomycin-resistant enterococci: an important infection control variable. , 1998, Archives of internal medicine.

[9]  R. Anderson,et al.  Vancomycin-resistant enterococci in intensive-care hospital settings: transmission dynamics, persistence, and the impact of infection control programs. , 1999, Proceedings of the National Academy of Sciences of the United States of America.

[10]  M. Bonten,et al.  Characteristics of polyclonal endemicity of Pseudomonas aeruginosa colonization in intensive care units. Implications for infection control. , 1999, American journal of respiratory and critical care medicine.

[11]  B. Cooper,et al.  Preliminary analysis of the transmission dynamics of nosocomial infections: stochastic and management effects. , 1999, The Journal of hospital infection.

[12]  I. Nåsell,et al.  On the quasi-stationary distribution of the stochastic logistic epidemic. , 1999, Mathematical biosciences.

[13]  Carl T. Bergstrom,et al.  The epidemiology of antibiotic resistance in hospitals: paradoxes and prescriptions. , 2000, Proceedings of the National Academy of Sciences of the United States of America.

[14]  B. de Jonghe,et al.  “Colonization Pressure” and Risk of Acquisition of Methicillin-Resistant Staphylococcus aureus in a Medical Intensive Care Unit , 2000, Infection Control & Hospital Epidemiology.

[15]  R. Weinstein,et al.  Infection control in intensive care units and prevention of ventilator-associated pneumonia. , 2000, Seminars in respiratory infections.

[16]  B. Murray,et al.  Vancomycin-resistant enterococcal infections. , 2000, The New England journal of medicine.

[17]  H. Andersson,et al.  Stochastic Epidemic Models and Their Statistical Analysis , 2000 .

[18]  M. Kollef,et al.  Acquisition of vancomycin-resistant enterococci during scheduled antimicrobial rotation in an intensive care unit. , 2001, Clinical infectious diseases : an official publication of the Infectious Diseases Society of America.

[19]  A. Belkum,et al.  Enterobacter species in a pediatric hospital: horizontal transfer or selection in individual patients? , 2001, The Journal of infectious diseases.