Our analysis included only those patients who had surveillance testing performed to accurately classify patient colonization status on admission. Patients could have been hospitalized multiple times during our analysis period; however, we restricted our analysis to the first hospitalization for each patient over the 8-year period to simplify interpretation of each identified infection.
In analyses with postdischarge MRSA infections as the outcome, we excluded patients who had predischarge MRSA infections so as to capture only incident infections. We categorized patients as not colonized, importers, or acquirers based on the presence of positive MRSA surveillance tests during their inpatient stay.
A patient whose admission MRSA screen and all subsequent screens were negative was classified as not colonized. An importer was one who had a positive MRSA screen upon admission to a facility. An acquirer was defined as a patient who was negative for MRSA on facility admission screening but had a subsequent positive MRSA screen upon unit-to-unit transfer or discharge.
During the predischarge period, patients could switch from being not colonized to being an acquirer at the time of their acquisition. We calculated the proportion of MRSA infections that occurred prior to discharge and at 30, 90, , and days after discharge for each of the 3 colonization groups. We identified positive MRSA cultures from the electronic microbiology data and used 3 definitions to classify these positive cultures as infections. In the most rigorous definition, the culture was deemed an infection if it was taken from a previously sterile body site eg, blood, bone, or a device.
Next, we expanded this definition to include cultures taken from nonsterile sites that were accompanied by prescription of a MRSA-specific antibiotic ie, parenteral vancomycin, daptomycin, linezolid, clindamycin, doxycycline, or trimethoprim-sulfamethoxazole within 5 days of the culture date [ 11 ]. We stratified these calculations by whether the patient was admitted directly to the intensive care unit ICU.
We performed multivariable regression analysis to examine the association between colonization status and pre- and postdischarge infections. A Cox proportional hazards model with time-varying covariates was used for the predischarge infection outcome.
In this analysis, patients who acquired MRSA colonization contributed person-time to the not colonized group prior to acquisition. For postdischarge infection outcomes, we used logistic regression. In secondary analyses, we also stratified these models by whether the patient was admitted directly to the ICU.
All statistical analyses were performed using SAS version 9. Fully of these who did not have a MRSA infection during hospitalization were followed for infection after discharge. Overall, The median time to acquisition was 14 interquartile range, 6—33 days. The mean median duration of hospitalization for those who did not have predischarge MRSA infections was 4.
Before hospital discharge, there were sterile site MRSA infections that appeared in the patients in our cohort who were not admitted to the ICU and in those who were admitted to the ICU during the 8-year analysis period Table 1.
Only 0. This increased approximately 7-fold for those admitted to an ICU. Expanding the definition of MRSA infection to include cultures from sterile sites that included an anti-MRSA antibiotic increased the percentage of individuals in each colonization category who had an infection, as did including all nonsurveillance MRSA cultures Table 1.
In the latter category, MRSA infection rates ranged from 1. Across all MRSA infection definitions and venues, the unadjusted relative risk for infection was As in the case of predischarge infections, patients who were colonized had the highest risk of infection and the percentage of those who progressed to infection was similar between those who imported and those who acquired colonization during hospitalization.
For instance, during the day postdischarge period, 4. Compared to those without colonization, the relative risk of MRSA infection was 8. For these patients, 4. The relative risk of infection during this time period was 6. The proportion of MRSA infections that occurred after discharge was dependent upon the colonization category and the interval evaluated since discharge Figure 1.
When measured at days postdischarge, For acquirers, this value was Percentage of all methicillin-resistant Staphylococcus aureus MRSA infections identified after hospital discharge by predischarge colonization status. In a multivariable regression analysis accounting for patient demographics and other confounders, the hazard ratio for a predischarge MRSA infection defined as a positive nonsurveillance culture was During the day postdischarge period, the odds ratios for infection relative to those not colonized were 7.
Finally, results were similar after stratifying on direct ICU admission Supplementary Tables 1 and 2. Cox proportional hazards regression was used for predischarge analysis while logistic regression was used for postdischarge analyses. Multivariable regressions control for age, sex, race, marital status, insurance status, comorbidity index, surgery during the first 48 hours of the hospitalization, calendar year, direct admission to intensive care unit, colonization pressure, and the Veterans Affairs hospital in which the admission occurred.
Being colonized with MRSA increases the risk of subsequent infection during and after hospitalization. For Veterans in our cohort who were not admitted directly to the ICU, 5. For those with a direct admission to the ICU, This relative increase in infection risk remained elevated over the 1-year period following discharge. Others studies have reported MRSA infection rates among colonized patients that are up to fold higher than what we found in our analysis [ 14—17 ].
However, comparison with our results is difficult because of differences in colonization definitions, venues, and length of follow-up. For instance, several studies were limited to single units in acute care ICU, transplant , long-term care, or outbreaks, or were performed before the advent of efficacious bundles to prevent central line bloodstream infections and ventilator-associated pneumonias [ 18 , 19 ].
Perhaps more importantly, differences in infection rates may be due to our use of universal surveillance to identify colonized patients compared to others who may have relied primarily on clinical cultures [ 14—16 ]. We and others have shown that universal surveillance identifies approximately 10 times as many colonized patients compared to clinical cultures alone [ 8 , 20 ].
Of note, our estimate of MRSA infection rates among colonized patients is more in line with those who used universal surveillance. Robicsek et al, for instance, found that 7. We did not find a significant difference in MRSA infection risk between importers and acquirers.
In one study, the risk of MRSA bacteremia was fold higher for importers and fold higher for acquirers compared to those who remained noncolonized [ 24 ].
Our unique data also allowed us to identify MRSA infections that occurred following hospital discharge. Our results show that a sizable portion of likely hospital-acquired MRSA infections presented after discharge, and, not surprisingly, this portion increases as the follow-up interval increases.
For both importers and acquirers, nearly two-thirds of the total MRSA infections in both the predischarge and day postdischarge time periods occurred during the postdischarge period.
The optimal time for follow-up that provides the best likelihood that an infecting organism is a clone of that acquired during hospitalization is not precisely known. Several recent studies have linked colonizing and infecting organisms across wide ranges of time between the colonization and infection events. It has been shown, for instance, that colonizing S. The results of our analyses are consistent with previous studies showing that MRSA colonization during hospitalization places patients at an increased risk for postdischarge infection.
In a matched-cohort study of patients admitted to a VA hospital and followed for 2 years, there were no culture-proven MRSA infections on readmission among noncarriers, but Others have shown that inclusion of day postdischarge data tripled the incidence of acute care hospital-onset MRSA infections, with the median onset being 12 days after discharge [ 30 ]. In a recent analysis from the Centers for Disease Control and Prevention, nearly two-thirds of previously hospitalized patients who subsequently developed invasive MRSA developed their infection within 3 months of hospital discharge, consistent with a higher risk of invasive MRSA in the weeks following hospitalization [ 1 ].
These data are consistent with the median time from MRSA detection to invasive disease reported by others Our results are important in the context of the recent debate over the appropriate role of contact precautions for MRSA, highlighted by several high-profile opinion pieces [ 32 , 33 ]. Our data suggest that contact precautions would likely have a small effect on predischarge HAIs but a larger effect on postdischarge HAIs. For these reasons, the value of contact precautions for MRSA should be judged in the context of infections that occur only in acquirers excluding importers since acquisition is what contact precautions are designed to prevent and should include infections that occur after discharge.
Our study has several limitations. First, patients may have sought care outside the VA system following discharge. Because we were only able to identify postdischarge patient outcomes through encounters at VA facilities, we have not accounted for postdischarge infections that were identified in non-VA settings. Second, the standardized protocols at VA hospitals during this time indicated that surveillance specimens were to be taken from the nares.
However, patients can carry MRSA in other locations on their body. Therefore, some patients who were colonized with MRSA may have been misclassified as not colonized in our data. Third, because of the difficulty in identifying true infections from electronic microbiology data, we used several definitions of MRSA infection. It is possible that some of these positive cultures were not true infections and that we missed some infections whose isolates were taken from nonsterile sites and not treated.
The challenges of identifying infections in the electronic data extend to the timing of infection as well. In our experience, while the VA microbiology data accurately capture the timing of culture collection or processing by the laboratory, there may be a small number of instances in which this does not accurately represent the timing of infection. For example, a culture may be delayed because a clinician initially feels that empiric treatment without culture is sufficient or because of a surgical procedure.
Finally, isolates were not collected from surveillance and subsequent infection and compared to confirm clonality, although others have shown that MRSA infection in Veterans following initial colonization is caused by the same strain in many cases [ 28 ]. There are five risk factors for getting MRSA in the community: Living in in crowded places such as corrections facilities. Being in close contact with someone who has MRSA, such as in contact sports.
Living in a place that isn't clean. Sharing used personal items such as towels, clothes, or razors. Having cuts, cracked skin, or open sores.
There are simple things you can do to stop MRSA and other germs from spreading: Clean your hands regularly with soap and water or alcohol-based hand rub hand sanitizer.
This is the best way to stop germs from spreading. Clean your home regularly, especially the kitchen and bathroom. Wash clothing using regular laundry soap in the regular wash cycle. Clean shared items like sports equipment and counters with a household disinfectant. See a doctor if you have any signs of an infection such as pain and fever. Cover wounds that are draining with a clean, dry dressing.
Current as of: April 12, Home About MyHealth. Include Images Large Print. In order to determine whether MRSA colonization is present, patients undergo screening, and specimens are collected from the nares using nasal swabs.
Specimens from extranasal sites, such as the groin, are sometimes also obtained for screening. These screening tests are usually done with either cultures or polymerase chain reaction testing. There is significant variability in the details of screening and decolonization protocols among different healthcare facilities.
Typically, the screening test costs more than the agents used for decolonization. Partly for this reason, some facilities forego screening altogether, instead treating all patients with a decolonization regimen; however, there is concern that administering decolonizing medications to all patients would lead to the unnecessary treatment of large numbers of patients.
Such widespread use of the decolonizing agents might promote the development of resistance to these medications. Decolonization typically involves the use of a topical antibiotic, most commonly mupirocin, which is applied to the nares. This may be used in conjunction with an oral antimicrobial agent. To increase the likelihood of successful decolonization, an antiseptic agent, such as chlorhexidine gluconate, may also be applied to the skin.
Chlorhexidine gluconate is also commonly used to prevent other HAIs. Neomycin is sometimes used for decolonization, but its efficacy for this purpose is questionable. There are also concerns about resistance, but it may be an option in cases of documented mupirocin resistance.
Preparations that contain tea tree oil appear to be more effective for decolonization of skin sites than for nasal decolonization. Table 1 lists the topical antibiotics and antiseptics that may be utilized for decolonization, while Table 2 lists the oral medications that can be used for this purpose.
Table 3 lists investigational agents being evaluated for their ability to decolonize patients. It has been suggested that the patients who might derive the most benefit from decolonization are those at increased risk for developing a MRSA infection during a specific time interval.
This would include patients who are admitted to the ICU for an acute illness and cardiothoracic surgery patients. A benefit from decolonization has also been observed in hemodialysis patients, who have an incidence of invasive MRSA infections times greater than the general population. Otherwise, there are no data to support the routine use of decolonization in nonsurgical patients. It is not uncommon for hospitals to screen patients admitted to the ICU for MRSA nasal colonization; in fact, screening is mandatory in nine states.
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