Nationwide Organism Susceptibility Patterns to Common Preoperative Prophylactic Antibiotics: What Are We Covering?

BACKGROUND: Many periprosthetic joint infections (PJIs) are caused by organisms not susceptible to first-generation cephalosporins. We sought to evaluate the national susceptibility patterns of organisms to cefazolin and, or oxacillin, clindamycin, and vancomycin using antibiogram data.

METHODS: Publically available regional and state antibiograms were evaluated for antibiotic susceptibility patterns to commonly infecting gram-positive organisms. The number of isolates tested in each antibiogram and percent of strains susceptible to oxacillin, clindamycin, and vancomycin were recorded. Oxacillin is used as a surrogate to cefazolin in antibiograms. A comparison of antibiotic susceptibilities was performed.

RESULTS: Seven state and 38 regional antibiograms were reviewed. Oxacillin was a sensitive antibiotic in 99.2 ± 4.8% of methicillin-sensitive Staphylococcus aureus (MSSA) isolates, 0 ± 0% of methicillin-resistant Staphylococcus aureus (MRSA) isolates, 44.5 ± 13.7% of coagulase-negative staphylococcus organism isolates (CNS), and 30.6 ± 10.5% of Staphylococcus epidermidis isolates. Clindamycin was a sensitive antibiotic in 75.8 ± 8.4% of MSSA isolates, 60.2 ± 13.2% of MRSA isolates, 60.3 ± 11.4% of CNS isolates, and 56.2 ± 6.5% of S epidermidis isolates. Vancomycin was a sensitive antibiotic in 99.9 ± 0.4% of MSSA isolates, 99.8 ± 0.4% of MRSA isolates, 99.8 ± 0.5% of CNS isolates, and 99.6 ± 0.7% of S epidermidis isolates. Clindamycin was significantly less sensitive in MSSA isolates as compared with oxacillin and vancomycin (P < .0001). Oxacillin was significantly less sensitive in CNS, S epidermidis, and MRSA isolates as compared with clindamycin and vancomycin (P < .0001).

CONCLUSION: The national clindamycin susceptibility pattern is limited to MSSA and may not have an optimal susceptibility profile suitable for use as a prophylactic antibiotic. Cefazolin continues to have excellent coverage against MSSA.