2075. Multidrug-Resistant Organism (MDRO) Co-Carriage Patterns in Nursing Homes (NHs): Methicillin-resistant Staphylococcus aureus (MRSA), Vancomycin-resistant Enterococci (VRE), Extended Spectrum beta-lactamase (ESBL) producers, Carbapenem-resistant Enterobacterales (CRE), Carbapenem-resistant Acinetobacter baumannii (CRAB), and Candida auris
Authors: Gussin Gabrielle , Singh Raveena D , Saavedra Raheeb , Nguyen Connie , Mitchell John , Nguyen Kristine , Gadia Gabriel , Vu Steven , Lee Alice , Shimabukuro Julie A , Bittencourt Cassiana E , Huang Susan S 
Published: November 2023

Abstract

Background
NHs are high-risk settings for MDRO spread.

Methods
We evaluated NH MDRO prevalence and co-carriage patterns in 22 NHs in Orange County, CA from Fall 2022-Spring 2023. 25 MDRO sweeps each involved 50 randomly-sampled occupied beds. Residents had swabs collected from bilateral axilla/groin and peri-rectal areas (MRSA, VRE, ESBL, CRE, CRAB, C. auris), and from bilateral nares (MRSA, C. auris). We assessed overall MDRO prevalence, as well as MDRO co-carriage patterns across organisms and MDRO body site carriage for each pathogen.

Results
Of 1250 residents, 57.5% (719) had MDRO carriage at any body site. Prevalence was highest for MRSA (36.7%), followed by ESBL (24.9%), VRE (14.2%), C. auris (7.1%), CRAB (2.1%), and CRE (1.0%). Of the 719 MDRO carriers, 62.2% (447) carried 1 MDRO and 37.8% (272) carried ≥2 MDROs. Carriers of one MDRO were likely to carry another (Table 1). For example, MRSA carriers had 48.1% likelihood of carrying another MDRO. Conversely, carriers of any other MDRO had a 45.9% (range: 44.9%-69.2%) likelihood of carrying MRSA. Notably, all CRE carriers and 92.3% of CRAB carriers carried another MDRO. Table 2 shows common body sites for carriage of each MDRO. Nares was the most common site of MRSA carriage; axilla/groin, for CRE and C. auris; peri-rectal areas, for VRE and ESBL; and axilla/groin and peri-rectal carriage, for CRAB.
This table represents patterns of multidrug-resistant organism (MDRO) co-carriage among nursing home (NH) residents, for MDROs including Methicillin-resistant Staphylococcus aureus (MRSA), Vancomycin-resistant Enterococci (VRE), Extended Spectrum beta-lactamase (ESBL) producers, Carbapenem-resistant Enterobacterales (CRE), Carbapenem-resistant Acinetobacter baumannii (CRAB), and Candida auris. Each row shows the prevalence of MDRO co-carriage for a specific pathogen. For example, the first row shows MDRO co-carriage patterns among 459 MRSA carriers. MRSA carriers had 48.1% likelihood of carrying any other MDRO. Conversely, the last row shows that carriers of any MDRO other than MRSA had a 45.9% likelihood of carrying MRSA whereas carriers of any MDRO other than C. auris had a 9.2% likelihood of carrying C. auris.
This table shows body site carriage of multidrug-resistant organisms (MDROs) among nursing home residents, for MDROs including Methicillin-resistant Staphylococcus aureus (MRSA), Vancomycin-resistant Enterococci (VRE), Extended Spectrum beta-lactamase (ESBL) producers, Carbapenem-resistant Enterobacterales (CRE), Carbapenem-resistant Acinetobacter baumannii (CRAB), and Candida auris. For each pathogen, the number and percent of carriers are shown per body site (axilla/groin, peri-rectal, nares). The dominant site of carriage for each MDRO is as follows: nares for MRSA (76.0%), peri-rectal for VRE (88.1%) and ESBL (84.6%), axilla/groin for CRE (76.9%) and C. auris (88.8%). Axilla/groin and peri-rectal sites had equal carriage for CRAB (63.2% each). By necessity, all dominant sites were the most common body site for solo carriage. For example, among nursing home residents with MRSA nares carriage, (42.1%) had MRSA only in the nares and 57.9% had MRSA at another body site.

Conclusion
Multi-MDRO carriage is common among NH residents with MDROs harbored at multiple body sites. Co-carriage was especially high among those harboring a carbapenem-resistant organism, likely reflecting accrued MDROs from extensive and repeated antibiotic exposure. Understanding MDRO co-carriage patterns can identify strategies that may be effective across MDROs. For example, nearly half of residents colonized with a non-MRSA MDRO also carried MRSA, suggesting that nasal decolonization of any MDRO carrier may benefit outcomes for MRSA, the most common MDRO in NHs.

Disclosures
Gabrielle Gussin, MS, Medline Industries, Inc: Conducted studies where participating hospitals/nursing homes received cleaning & antiseptic product|Xttrium Laboratories: Conducted studies where participating hospitals & nursing homes received antiseptic bathing product Raveena D. Singh, MA, Medline Industries, Inc: Conducted studies where participating hospitals/nursing homes received cleaning & antiseptic product|Xttrium Laboratories: Conducted studies where participating hospitals & nursing homes received antiseptic bathing product Raheeb Saavedra, AS, Medline Industries, Inc: Conducted studies where participating hospitals/nursing homes received cleaning & antiseptic product|Xttrium Laboratories: Conducted studies where participating hospitals & nursing homes received antiseptic bathing product Connie Nguyen, n/a, Xttrium Laboratories: Conducted studies where participating hospitals & nursing homes received antiseptic bathing product Alice Lee, n/a, Xttrium Laboratories: Conducted studies where participating hospitals & nursing homes received antiseptic bathing product Susan S. Huang, MD, MPH, Medline: Conducted studies in which participating nursing homes received contributed antiseptic bathing and cleaning products|Xttrium: Conducted studies in which participating nursing homes and hospital patients received contributed antiseptic soap