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Table 1 Parameters and initial occupancy for the co-colonization model

From: Identifying conditions for elimination and epidemic potential of methicillin-resistant Staphylococcus aureus in nursing homes

Description Symbol Value (95 % CI) Estimated or Observed
Initial occupancy in each compartment
Number of residents susceptible to any MRSA S 350 observed
Number of residents colonized with non-USA300 I 1 79 observed
Number of residents colonized with USA300 I 3 14 observed
Number of residents co-colonized with non-USA300 and USA300 I b 3 observed
Total number of residents N 446 observed
Model Parameters
Probability of admission of MRSA-colonized residents λ 0.215 estimated
Discharge rate of susceptibles (per 3 months) γ S 0.101 estimated
Discharge rate of MRSA-colonized (per 3 months) γ I 0.074 estimated
Proportion of residents colonized with non-USA300 at baseline w 1 0.823 observed
Proportion of residents colonized with USA300 at baseline w 3 0.146 observed
Proportion of residents co-colonized with both strains at baseline w b 0.031 observed
Acquisition rate for non-USA300a b 1n   
 - generalb   0.029 (0.022, 0.038) estimated
 - w/o ABc   0.020 (0.014, 0.030) estimated
 - with ABd   0.042 (0.030, 0.061) estimated
Acquisition rate for USA300a b 3n   
 - generalb   0.006 (0.004, 0.011) estimated
 - w/o ABc   0.004 (0.002, 0.010) estimated
 - with ABd   0.009 (0.005, 0.019) estimated
Clearance rate for non-USA300a g n1   
 - generalb   0.116 (0.088, 0.152) estimated
 - w/o ABc   0.125 (0.086, 0.179) estimated
 - with ABd   0.107 (0.074, 0.163) estimated
Clearance rate for USA300a g n3   
 - generalb   0.137 (0.082, 0.228) estimated
 - w/o ABc   0.155 (0.079, 0.328) estimated
 - with ABd   0.125 (0.064, 0.266) estimated
  1. AB, antibiotic use in the past 3 months
  2. aRelative frequency per 3 months
  3. bThe rate irrespective of antibiotic use in the past 3 months
  4. cThe rate corresponding to No level of antibiotic use in the past 3 months
  5. dThe rate corresponding to Yes level of antibiotic use in the past 3 months