Microbiology testing around the time of antibiotic initiation among residents of long-term care facilities.

BACKGROUND AND

OBJECTIVES

While microbiology tests can guide management of infectious diseases, little is known about the prevalence of testing around the time of antibiotic initiation in long-term care facilities (LTCFs). The objectives of this study were to investigate prevalence and factors associated with microbiology testing around the time of antibiotic initiation, and subsequent treatment pathways in LTCFs.

METHODS

This retrospective cohort study included individuals aged ≥65 years who entered a LTCF in three Australian states between 1 January 2017 and 30 June 2019, and received a systemic antibiotic (n = 36 977). Prevalence of microbiology testing in the 14 days pre- and 7 days post-antibiotic initiation, and treatment pathways 14 days post-initiation, were determined. Multivariable logistic regression determined adjusted odds ratios (aORs) and 95% confidence intervals (95%CIs) for factors associated with testing.

RESULTS

In total 15 407 (41.7%) individuals were tested around the time of antibiotic initiation, ranging from 22.9% (n = 585/2551 residents) of macrolide initiators to 79.3% (n = 413/521) of nitrofurantoin initiators. Individuals with urinary tract infections on LTCF entry (aOR 1.24, 95%CI 1.10-1.40) or initiating trimethoprim (aOR 2.80, 95%CI 2.50-3.13) were more likely to be tested. Males (aOR 0.81, 95%CI 0.77-0.85), and residents who received cephalosporins (aOR 0.75, 95%CI 0.68-0.84), penicillins (aOR 0.49, 95%CI 0.45-0.55), or with airways disease (aOR 0.87, 95%CI 0.82-0.91) had lower odds of testing. Among those tested, 14.5% (n = 2238) had a second dispensing of the same antibiotic, 11.4% (n = 1 751) switched antibiotic therapy and 5.9% (n = 904) were hospitalized within 14 days.

CONCLUSIONS

With four in ten residents tested, and lower prevalence within certain resident subgroups, this study suggests a high dependence on initiating empiric therapy in LTCFs.