Modeling methicillin-resistant Staphylococcus aureus in hospitals: Transmission dynamics, antibiotic usage and its history

Table 1 List of parameters for MRSA transmission in hospital settings

Description	Symbol	Value	References
Total number of patients	N _p	600
Total number of HCWs	N _h	150
(Patients: HCWs = 3:1)			[19]
Probability that a person is colonized by MRSA at admission	λ _c	0.04	[24]
Probability that a person is infected with MRSA at admission	λ _i	0.001	[25]
Average length of stay of an uncolonized patient (days)	1/γ_u	5	[24]
Average length of stay of a colonized patient (days)	1/κ	7	[20]
Probability of becoming infectious	m ₁	0.3	[23]
Probability of decolonization	m ₂	0.01	estimated^∗
Rate of progression from colonization to infection	ϕ	m ₁ κ
Rate of decolonization	ω	m ₂ κ
Discharge rate of colonized patients	γ _c	(1 − m₁ − m₂)κ
(including death from other causes)
Average duration of treatment of an infected patient (days)	1/τ	14	[1]
Probability of a successful treatment	ρ	0.6	[26]
Death rate of an infected patient	γ _i	(1 − ρ)τ
(from both disease-related and other causes)
Total number of contacts that a patient requires per day	a	8	[19]
Probability of colonization after a contact with a HCW	b _p	0.01	[27]
Probability of contamination after a contact with a colonized patient	b _hc	0.15	[27]
Probability of contamination after a contact with an infected patient	b _hi	0.30	estimated
Average duration of contamination (days)	1/μ	1/24	[27]

^*Note that the probability of decolonization of a colonized patient is estimated by the normal time require for nasal MRSA to revert to the usual MSSA (methicillin-sensitive Staphylococcus aureus) which is approximately 30 days[28]. Hence, we here estimate the probability of decolonization by probability that a patient stays longer than thirty days[29].

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