Antibiograms Cannot Be Used Interchangeably Between Acute Care Medical Centers and Affiliated Nursing Homes

Document Type


Date of Original Version



Objective: To determine whether antibiograms for Veterans Affairs (VA) nursing homes (NHs), termed Community Living Centers, are similar to those from their affiliated acute care medical centers. Design: Descriptive study. Setting and participants: We compared the 2017 antibiograms for VA NHs to their affiliated VA medical centers (VAMCs). Antibiograms included antibiotic susceptibility rates for commonly observed bacteria in this setting (Staphylococcus aureus, Enterococcus spp, Escherichia coli, Klebsiella spp, Proteus mirabilis, and Pseudomonas aeruginosa). Methods: Antibiograms were considered to be in complete agreement when the overall susceptibility rate between the NH and affiliated VAMC was either at or above 80% or below 80% across all bacteria and antibiotics. Average percentage of bacteria-antibiotic comparisons in disagreement per facility pair, and number of facilities with agreement for specific bacteria-antibiotic comparisons were also assessed. The chi-square test was used to compare disagreement between NH-VAMC facilities based on geographic proximity of the NH to the VAMC, culture source, and bed size. Results: A total of 119 NH-VAMC affiliate pairs were included in this analysis, with 71% (84/119) on the same campus and 29% (35/119) on geographically distinct campuses. None of the NH-VAMC pairs demonstrated complete agreement (all bacteria vs all antibiotics) between their antibiograms. On average, 20% of the bacteria-antibiotic comparisons from the antibiogram disagreed clinically per NH-VAMC pair, and almost twice as often the nursing home had lower susceptibility (higher resistance) than the acute care facility. Some bacteria-antibiotic comparisons agreed in all facilities (eg, E coli–imipenem; S aureus–linezolid; S aureus–vancomycin), while others showed greater disagreement (eg, Klebsiella spp–cefazolin; Klebsiella spp–ampicillin-sulbactam; P aeruginosa–ciprofloxacin). Rates of clinical disagreement were similar by geographic proximity of the NH to the VAMC, culture source, and bed size. Conclusions and implications: Overall, this study showed a moderate lack of agreement between VA NH antibiograms and their affiliate VAMC antibiograms. Our data suggest that antibiograms of acute care facilities are often not accurate approximations of the nursing home resistance patterns and therefore should be used with caution (if at all) in guiding empiric antibiotic therapy.

Publication Title

Journal of the American Medical Directors Association