Introduction
Nursing Facilities (NF) integrally serve the larger healthcare system by providing temporary care to acutely-ill patients with skilled nursing needs before safely transitioning back to their homes. However, patients transferred from hospitals to NFs are also more likely to be colonized by multi-drug resistant organisms (MDROs), which commonly cause healthcare-associated infections.1 Infection prevention and control efforts have focused mostly on acute care, successfully reducing incidence of methicillin-resistant Staphylococcus aureus (MRSA) colonization by 31% from 2005–2011 in hospitals.2 Meanwhile, enterococcal infections and colonization with vancomycin-resistant Enterococcus species (VRE) have arisen, often with serious clinical implications, including a doubling in VRE related hospital discharges.3,4
Methods
In response, this investigation examined whether NFs mirrored these national trends in MRSA and VRE, using data from four sequential multi-site NF studies in Southeast Michigan between 2003 and 2016: a cross-sectional study (Study A) conducted 2003–2004 (14 NFs, 208 residents);5 prospective Studies B (2005–2010, 15 NFs, 178 residents),6 and C (2010–2013, 12 NFs, 414 residents);7 and the first phase of an ongoing prospective Study D (2014–2016, 6 NFs, 651 residents).1 Study C was limited to residents with a feeding tube or urinary catheter, while the other studies included individuals with and without devices. For all studies, swabs were collected at time of enrollment from residents’ nares, oropharynx, groin, perianal area, and wounds and tested for MRSA, VRE, and ceftazidime-resistant gram-negative bacteria (CTZ R-GNB). Standard microbiological methods were used by trained research staff and were conducted in the same research lab for all four studies.1, 5–7 All studies were approved by the institutional review board at the University of Michigan. Written informed consent was obtained from each resident or his or her durable power of attorney.
Results
The mean study age ranged from 74.7 (SD=12.2) years in the period 2014–2016 to 80.5 (SD=11.0) in the period 2005–2010. Prevalence of MRSA declined in each sequential study, while prevalence of VRE increased over time (Table 1). In the earliest study, 37.1% of participants were colonized with MRSA and 9.9% were colonized with VRE. In comparison, a smaller proportion of the most recent study, 13.4%, was colonized with MRSA, while a larger proportion, 28.9% was colonized with VRE. These trends hold true in the subset of high-risk patients with devices (Table 1) where we showed MRSA colonization at 48% in Cohort A (2003–2004) compared to 16.4% in Cohort D (2014–2016); however, VRE increased from 9.0% to 44.8% from Cohort A to Cohort D. These trends among patients with devices are more pronounced than those in patients with no devices: we show a 2.9% decrease in MRSA among device patients compared to a 2.1% decrease among no-device patients; a 5.0% increase in VRE compared to a 2.6% increase among no-device patients.
Table 1.
Trends in MDRO Colonization from 2005–2016
| Cohort A | Cohort B | Cohort C** | Cohort D | |
|---|---|---|---|---|
| 2003–2004 (n=208) | 2005–2010 (n=178) | 2010–2013 (n=414) | 2014–2016 (n=651) | |
| All participants | ||||
| MRSA | 37.1 (30.8, 43.8) | 20.2 (14.9, 26.8) | 17.8 (14.4, 21.8) | 13.4 (11.0, 16.2) |
| VRE | 9.9 (6.5, 14.7) | 9.6 (6.0, 14.8) | 15.1 (12.0, 18.9) | 28.9 (25.5, 32.5) |
| CTZR-GNB | 12.2 (8.4, 17.3) | 9.6 (6.0, 14.8) | 18.3 (14.8, 22.3) | 10.6 (8.5, 13.2) |
| Any MDRO | 46.0 (39.4, 52.8) | 28.7 (22.5, 35.7) | 37.3 (32.7, 42.0) | 41.0 (37.3, 44.8) |
| Any Devices | ||||
| MRSA | 48.0 (38.3, 57.8) | 24.4 (16.6, 34.4) | 17.8 (14.4, 21.8) | 16.4 (9.3, 27.4) |
| VRE | 9.0 (4.7, 16.5) | 15.6 (9.4, 24.6) | 15.1 (12.0, 18.9) | 44.8 (33.3, 56.9) |
| CTZR-GNB | 20.0 (13.2, 29.1) | 15.6 (9.4, 24.6) | 18.3 (14.8, 22.3) | 19.4 (11.6, 30.7) |
| Any MDRO | 57.0 (47.1, 66.4) | 38.9 (29.3, 49.4) | 37.3 (32.7, 42.0) | 56.7 (44.6, 68.1) |
| No Devices | ||||
| MRSA | 27.4 (20.0, 36.4) | 15.9 (9.6, 25.2) | -- | 13.0 (10.5, 16.0) |
| VRE | 10.6 (6.1, 17.8) | 3.4 (1.1, 10.1) | -- | 27.1 (23.6, 30.8) |
| CTZR-GNB | 5.3 (2.4, 11.4) | 3.4 (1.1, 10.1) | -- | 9.6 (7.4, 12.3) |
| Any MDRO | 36.3 (27.9, 45.6) | 18.2 (11.4, 27.7) | -- | 39.2 (35.3, 43.2) |
Proportion of residents colonized at baseline and (95% CI) are given.
Cohort C only included patients with either a urinary catheter or a feeding tube. We show similar trends in MRSA and VRE in nursing facility patients with and without indwelling devices.
Discussion
Our findings indicate that MRSA colonization in Southeast Michigan NFs has steadily decreased since 2003, while prevalence of VRE has nearly tripled. A similar trend was reported within a single long-term acute care hospital in Chicago. In this study, Munoz et al reported an increase in VRE recovered from rectal swabs from 29% in 2005 to 44% in 2008.8 We now show this trend mirrored in NFs, indicating that interventions in reducing MDROs in hospitals will also benefit NF populations and thus develop a regional approach to combat antibiotic resistance.9
Our findings suggest several future directions. First, more studies are needed to confirm these trends in post-acute care and other alternative care settings from other geographic settings. Second, future infection prevention measures should focus on clinical consequences of increasing VRE, particularly in older adults. Third, it is important that healthcare facilities develop cost-effective, efficient MDRO surveillance strategies in order to characterize and understand long-term trends.
Acknowledgements
Financial Support.
NIH R01AG041780 (Mody, Min) and K24 AG050685 (Mody)
Thank you notes.
We thank the patients and their families who participated in the four described studies. We also thank Bonnie Lansing and Sara McNamara for their role in participant enrollment and data collection.
Footnotes
Conflicts of interest. All authors report no conflicts of interest relevant to this article.
References
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