Risk Factors for Community-Onset Methicillin-Resistant Staphylococcus aureus Bacteremia Público

Jacob, Jesse Thomas (2011)

Permanent URL: https://etd.library.emory.edu/concern/etds/3n203z750?locale=es
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Abstract

The characteristics and risk factors for bacteremia with methicillin-resistant
Staphylococcus aureus (MRSA) at the time of admission to an acute care hospital have
not been well characterized after the recent changes in MRSA epidemiology. All charts
for adults with S. aureus in blood cultures obtained within 48 hours of admission
(community-onset, CO) were reviewed over a five year period, with only the first episode
of S. aureus bacteremia per patient included in the analysis. Patients with MRSA
bacteremia were classified as cases, and those with methicillin-sensitive S. aureus
(MSSA) were used as the comparison group. Patients with CO MRSA bacteremia had a
median age of 59.4 (range: 37.1-87.2) and were 94.8% male and 48.8% black. The most
common co-morbidity was diabetes mellitus (54.4%). Patients with CO MSSA
bacteremia had similar demographic and clinical characteristics. Among the 84 cases and
58 comparators, there were similar rates for prior culture positivity with MSSA (6.0% vs.
5.2%), but only cases had prior positive culture with MRSA (14.3% vs. 0%, p<0.01).
Frequency of hospitalization was higher among cases (53.6% vs. 31.0%, p=0.01). In
univariate analysis, the major definable predictors of CO MRSA bacteremia were receipt
of oral (OR 3.19, p<0.01) and intravenous (OR 2.78, p<0.01) antibiotics as well as prior
hospitalization (OR 3.19, p<0.01). For patients who were previously hospitalized, the
OR for was 7.42 if they had received IV antibiotics, compared to 0.85 if they had not
received IV antibiotics (p=0.01). In multivariate analysis, the single greatest predictor of
CO MRSA bacteremia was hospitalization in the last 90 days among patients receiving
antibiotics (OR 6.12, p=0.01). Among those who did not receive antibiotics, no single
variable predicted outcome. Post-hospitalization surveillance interventions may be
important considerations in developing prevention strategies. Antimicrobial stewardship
may also pray a crucial role in decreasing the burden of MRSA bacteremia on the
healthcare system.

Table of Contents


INTRODUCTION ............................................................................................................................1
BACKGROUND .............................................................................................................................2
METHODS ...................................................................................................................................5
Setting .......................................................................................................................................5
Case and Comparisons Selection ................................................................................................. 5
Chart Review ............................................................................................................................. 6
Statistical Analysis ......................................................................................................................7
RESULTS .....................................................................................................................................8
Description of Cases ....................................................................................................................8
Cases and Comparators ...............................................................................................................9
Univariate and Multivariate Analysis .............................................................................................10
DISCUSSION ...............................................................................................................................12
REFERENCES ...............................................................................................................................17
TABLES and FIGURES ...................................................................................................................19

Table 1: Selected Characteristics of Patients with Community-Onset Methicillin-resistant

S. aureus (MRSA) Bacteremia ...........................................................................................19
Figure 1: Source of Methicillin-resistant S. aureus (MRSA) Bacteremia at Admission................. 20
Figure 2: Frequency of Community Onset-Methicillin Resistant S. aureus Bacteremia

by Quarter, 2005-2008 ................................................................................................... 21
Table 2: Frequency of Selected Characteristics of Patients with Community-Onset

S. aureus Bacteremia within 90 days ............................................................................... 22
Figure 3: Number of Community-Onset S. aureus Bacteremias by Months

Since Last Hospitalization ................................................................................................23
Table 3: Association of Selected Characteristics of Patients with Community-Onset

Methicillin-resistant S. aureus (MRSA) Bacteremia.................................................................24
Table 4: Assessment of Interaction of Hospitalization with Other Covariates........................... 25
Table 5: Multivariate Analysis of Risk Factors for Methicillin-resistant S. aureus (MRSA)

Compared to Methicillin-sensitive S. aureus Bacteremia: Basic Model.................................... 26
Tables 6A and 6B: Multivariate Analysis of Risk Factors for Methicillin-resistant S. aureus

(MRSA) Compared to Methicillin-sensitive S. aureus Bacteremia:

Basic Model Stratified by IV Antibiotics ............................................................................27
Tables 7A and 7B: Multivariate Analysis of Risk Factors for Methicillin-resistant S. aureus

(MRSA) Compared to Methicillin-sensitive S. aureus Bacteremia:

Extended Model Stratified by IV Antibiotics ......................................................................28
Table 8A and 8B: Final Model of Multivariate Analysis of Risk Factors for Methicillin-resistant

S. aureus (MRSA) Compared to Methicillin-sensitive S. aureus Bacteremia,

Stratified by IV Antibiotics...............................................................................................29
Table 9A and 9B: Sensitivity analysis excluding patients with prior Methicillin-resistant

S. aureus (MRSA) of the Final Model of Multivariate Analysis of Risk Factors for MRSA

Compared to Methicillin-sensitive S. aureus Bacteremia, Stratified by IV Antibiotics ........... 30
Table 10A and 10B: Sensitivity analysis excluding patients with infections in 2008 of the

Final Model of Multivariate Analysis of Risk Factors for Methicillin-resistant S. aureus (MRSA)

Compared to Methicillin-sensitive S. aureus Bacteremia, Stratified by IV Antibiotics............. 31

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