Occurence of Environmental Shedding of Methicillin-Resistant Staphylococcus aureus During Appointments Outside of Patient Rooms

methicillin-resistant Staphylococcus aureus bacteria
methicillin-resistant Staphylococcus aureus bacteria
Researchers conducted a cohort study to assess the frequency at which environmental shedding of methicillin-resistant Staphylococcus aureus occurs during inpatient and outpatient appointments.

Compared with multidrug-resistant Gram-negative bacilli (MDR-GNB), environmental shedding of methicillin-resistant Staphylococcus aureus (MRSA) occurred more frequently during inpatient and outpatient appointments, according to study results published in the American Journal of Infection Control.

A team of researchers in Ohio conducted an observational cohort study to assess the frequency of and risks associated with environmental shedding of MRSA and MDR-GNB by colonized patients during outpatient and inpatient appointments.

The study included patients with MRSA (n=39) or MDR-GNB (n=11) who had been hospitalized or recently discharged at the time of enrollment. Of the patients with MDR-GNB, 6 had carbapenem-resistant GNB and 5 had extended-spectrum β-lactamase-producing GNB.

Of the 15 incidences of patients who shed MRSA to the environment, 5 occurred during outpatient appointments and 10 occurred during inpatient appointments. Unlike patients with MRSA, those with MDR-GNB were not found to experience environmental shedding (15 vs 0; P =.02).

Among patients with wound cultures positive for MRSA, there was a significantly increased risk for environmental shedding (P =.008). Of the environmental MRSA isolates, 80% were found to be genetically related to concurrent nasal isolates via spa typing.

Study limitations included its single-center setting, inclusion of predominantly men, and exclusion of patients with other colonizing pathogens.

Although results of this study were consistent with previous studies on the environmental shedding of MRSA, additional multicenter studies are needed to investigate the environmental shedding of other pathogens, such as vancomycin-resistant Enterococcus, Clostridioides difficile, and Candida auris.

“These findings emphasize the importance of cleaning and disinfection of surfaces in areas such as radiology, physical therapy, and outpatient clinics,” the researchers wrote. “Further studies are needed to evaluate the effectiveness of other interventions such as chlorhexidine bathing and patient hand hygiene,” the researchers concluded.

Disclosure: One study author declared affiliations with manufacturing, health care, and/or pharmaceutical companies. Please refer to the original reference for a full list of disclosures.


Alhmidi H, Cadnum JL, Koganti S, Jencson AL, Wilson BM, Donskey CJ. Shedding of methicillin-resistant Staphylococcus aureus and multidrug-resistant gram-negative bacilli during outpatient appointments and procedures outside hospital rooms. Am J Infect Control. 2021;49(8):991-994. doi:10.1016/j.ajic.2021.03.002