Assessment of risk factors related to healthcare-associated methicillin-resistant Staphylococcus aureus infection at patient admission to an intensive care unit in Japan

Abstract

Background: Healthcare-associated methicillin-resistant Staphylococcus aureus (HA-MRSA) infection in intensive care unit (ICU) patients prolongs ICU stay and causes high mortality. Predicting HA-MRSA infection on admission can strengthen precautions against MRSA transmission. This study aimed to clarify the risk factors for HA-MRSA infection in an ICU from data obtained within 24 hours of patient ICU admission.

Methods: We prospectively studied HA-MRSA infection in 474 consecutive patients admitted for more than 2 days to our medical, surgical, and trauma ICU in a tertiary referral hospital in Japan. Data obtained from patients within 24 hours of ICU admission on 11 prognostic variables possibly related to outcome were evaluated to predict infection risk in the early phase of ICU stay. Stepwise multivariate logistic regression analysis was used to identify independent risk factors for HA-MRSA infection.

Results: Thirty patients (6.3%) had MRSA infection, and 444 patients (93.7%) were infection-free. Intubation, existence of open wound, treatment with antibiotics, and steroid administration, all occurring within 24 hours of ICU admission, were detected as independent prognostic indicators. Patients with intubation or open wound comprised 96.7% of MRSA-infected patients but only 57.4% of all patients admitted.

Conclusions: Four prognostic variables were found to be risk factors for HA-MRSA infection in ICU: intubation, open wound, treatment with antibiotics, and steroid administration, all occurring within 24 hours of ICU admission. Preemptive infection control in patients with these risk factors might effectively decrease HA-MRSA infection.

Figure 1

Flowchart showing overall incidence of acquisition and infection with healthcare-associated MRSA in the present study. MRSA: methicillin-resistant Staphylococcus aureus; ICU: intensive care unit.

Figure 2

Sensitivity for MRSA infection and number of patients with risk factors. Sensitivity for MRSA infection is plotted according to the number of patients with at least one of the four independent risk factors identified in the present study. A closed circle indicates sensitivity and number of patients with at least one of the 4 factors, an open circle indicates sensitivity and number of patients with at least one of 3 factors, an open square indicates sensitivity and number of patients with at least one of 2 factors, and a closed triangle indicates sensitivity and number of patients with only 1 factor. The combinations circumscribed by the ellipse were the best subset of a small group of patients with the highest sensitivity for MRSA infection. MRSA: methicillin-resistant Staphylococcus aureus; INT: intubation; OW: open wound; TA: treatment with antibiotics; ST: steroid administration.