# Treatment effect based on antimicrobial resistance in Staphylococcus aureus infections related to orthopedics

## TL;DR

This study examines antimicrobial resistance in Staphylococcus aureus infections related to orthopedics and evaluates treatment outcomes based on resistance patterns.

## Contribution

The study provides insights into the effectiveness of antimicrobial agents and treatment stages in managing S. aureus infections with resistance.

## Key findings

- Resistance rates ranged from 0.0 to 89.2%, with no resistance to vancomycin or linezolid observed.
- Clindamycin and levofloxacin were identified as active agents associated with better healing outcomes.
- Multidrug resistance was found in 42.9% of isolates, but was not related to age or gender.

## Abstract

Staphylococcus aureus is a prevalent pathogen in infections related to orthopedics. Here, we report on the antimicrobial resistance and treatment with emphasis on both clinical and microbiological perspectives. We recruited 196 patients with S. aureus isolates. Antimicrobial resistance was described by resistance rates, and multidrug resistance (MDR) was classified according to international standards. Antimicrobial agents were classified as active, untested, or inactive according to the antimicrobial susceptibility tests. The treatment stage was divided into empirical and targeted stages, and effects were classified as first-, second-, or third-grade healing. Resistance rates ranged from 0.0 to 89.2%, and no resistance to vancomycin or linezolid was found. As the signal of methicillin resistance, the incidence of oxacillin resistance was 21.0%. MDR was identified in 84 (42.9%) isolates, not related to gender (p = 0.505) or age (p = 0.459). Cefuroxime and cefazolin were common untested agents, whereas clindamycin and levofloxacin were common active agents used in treatment. Out of the participants, 173 had first-grade healing, 16 had second-grade healing, and 7 had third-grade healing. Of the patients who received active and untested agents, the numbers of patients who had first-, second-, and third-grade healing were 74, 6, and 4 vs. 99, 10, and 3 (p = 0.709), respectively. Among the patients who received untested agents during empirical treatment, 20.9% (28/134) switched to active agents for treatment success. Antimicrobial resistance is a prevalent concern, especially methicillin resistance. Active agents represented by clindamycin and levofloxacin are valuable according to antimicrobial susceptibility tests and clinical practice.