Mathematical Model of the Impact of a Nonantibiotic Treatment for Clostridium difficile on the Endemic Prevalence of Vancomycin-Resistant Enterococci in a Hospital Setting
Table 1
Parameters used in modeling the effect of antibiotic versus nonantibiotic treatment of CDAD on VRE colonization.
Parameter
Patients
Value
Np
number of patients in the hospital
400
ratio of patients to HCW
4
CDAD−, uncolonized, off antibiotic: admission rate
50.1 per day
CDAD−, uncolonized, off antibiotic: average length of stay
5 days
CDAD−, uncolonized, on antibiotic: admission rate
2.505 per day
CDAD−, uncolonized, on antibiotic: average length of stay
14 days
CDAD−, colonized, off antibiotic: admission rate
0.334 per day
CDAD−, colonized, off antibiotic: average length of stay
28 days
CDAD−, colonized, on antibiotic: admission rate
0.501 per day
CDAD−, colonized, on antibiotic: average length of stay
28 days
CDAD−, uncolonized, on antibiotic: stop antibiotic
15% per day
CDAD−, uncolonized, off antibiotic: start antibiotic
15% per day
CDAD−, colonized, on antibiotic: stop antibiotic
4% per day
CDAD−, colonized, off antibiotic: start antibiotic
16% per day
fraction of CDAD+, on antibiotic: stop antibiotic
0.5
average number of contacts between uncolonized
8 per day
CDAD− patients on antibiotic and HCW
average number of contacts between uncolonized
8 per day
CDAD+ patients on antibiotic and HCW
probability of colonization per contact between uncolonized
0.024
CDAD+ patient on antibiotic and contaminated HCW
probability of colonization per contact between uncolonized
0.06
CDAD− patient on antibiotic and contaminated HCW
CDAD−, uncolonized, on antibiotic: transit to CDAD+
1.07% per day
CDAD−, colonized, on antibiotic: transit to CDAD+
1.07% per day
CDAD+, colonized, on antibiotic: transit to CDAD−
27% per day
CDAD+, colonized, off antibiotic: transit to CDAD−
27% per day
CDAD+, uncolonized, on antibiotic: transit to CDAD−
27% per day
CDAD+, uncolonized, off antibiotic: transit to CDAD−
27% per day
fraction of AB patients that transit to CDAD+ and stop AB
0.0 or 0.5
Parameter
Health care workers
Value
average number of contacts between HCW and colonized CDAD+ patients
10 per day
average number of contacts between HCW and colonized CDAD+ patients
10 per day
probability of contamination per contact between uncontaminated
0.4
HCW and colonized CDAD− patient on antibiotic
probability of contamination per contact between uncontaminated
0.4
HCW and colonized CDAD− patient off antibiotic
probability of contamination per contact between uncontaminated
0.16
HCW and colonized CDAD+ patient on antibiotic
probability of contamination per contact between uncontaminated
0.16
HCW and colonized CDAD+ patient off antibiotic
average duration of HCW contamination
48 minutes
hand-washing compliance factor between 0 and 1
0.6
CDAD = clostridium difficile-associated disease; VRE = vancomycin-resistant enterococci; HCW = health care worker; CDAD+ = clostridium difficile-associated disease positive; CDAD− = clostridium difficile-associated disease negative; AB = antibiotics.