Risk factors for developing clinical infection with methicillin-resistant Staphylococcus aureus (MRSA) amongst hospital patients initially only colonized with MRSA

Abstract

In hospital outbreaks of methicillin-resistant Staphylococcus aureus (MRSA) many patients are initially colonized without infection. The reasons why some progress to infection while others do not are not known. A cohort of 479 hospital patients, initially only colonized with MRSA, was followed prospectively for the development of MRSA infection. Risk factors for progression to infection were assessed using Cox proportional hazards survival analysis. Fifty-three patients (11 .l%) developed 68 MRSA infections. Intensive care setting, administration of three or more antibiotics, ulcers, surgical wounds, nasogastric or endotracheal tubes, drains, and urinary or intravenous catheterization were all associated with increased rates of MRSA infection. Multivariate analysis showed that intensive care patients, compared with medical natients. had a higher rate of develoning MRSA infection within the first' four days of admission, with a hazard ra;o of 26.9 (95% CI 5.7-126). Surgical wounds, pressure ulcers and intravenous catheterization were also independent risk factors, with hazard ratios (and 95% CI) of 2.9 (1.3-6.3), 3.0 (1.6-5.7) and 4.7 (l+15.6), respectively. These findings suggest that, during an MRSA outbreak, clinical infection would be reduced if surgical and intensive care patients received priority for the prevention of initial colonization with MRSA. Prevention of pressure ulcers, and strict aseptic care of intravenous catheters and surgical wounds would also reduce the development of MRSA infection. Since early treatment with vancomycin is known to reduce the mortality, patients colonized with MRSA who also have one or more of these risk factors may warrant empirical vancomycin therapy at the earliest suggestion of infection.

Substantial Shifts in Ranking of California Hospitals by Hospital-Associated Methicillin-ResistantStaphylococcus aureusInfection Following Adjustment for Hospital Characteristics and Case Mix

“…Not surprisingly, these attributes are well known to be associated with a higher risk of HA-MRSA infection. [7][8][9]30 In addition, our study found that the proportion of admitted patients from lower socioeconomic backgrounds was also in-dependently predictive of a hospitals' proportion of HA-MRSA infections. The availability of resources in the home environment could influence the risk of HA infections that manifest in the immediate postdischarge period.…”

Does Colonization with Methicillin-Susceptible Staphylococcus aureus Protect against Nosocomial Acquisition of Methicillin-Resistant S. aureus?

“…[4][5][6][7] Patients who acquire MRSA incur significant risks of subsequent infection. [8][9][10] Importantly, MRSA carriage is associated with a fourfold increased infection risk compared with MSSA colonization. 11,12 Many studies have evaluated the risk factors for nosocomial MRSA acquisition (eg, comorbidities, exogenous factors, and antimicrobial exposure) to improve preventive measures, [13][14][15] but despite 50 years of research, less is known about the protective factors at the host level.…”

Duration of Methicillin-Resistant Staphylococcus aureus Carriage, According to Risk Factors for Acquisition

“…This rate is comparable with rates reported elsewhere. 1,29 Older age, intensive care unit stay, receipt of hemodialysis, presence of surgical wounds, presence of pressure ulcers, and use of intravascular catheters have been associated with an increased progression of MRSA colonization to invasive infection. 1,29 ' 30 In our study, a higher number of risk factors at the end of follow-up was associated with an increased risk of MRSA infection.…”