Antimicrobial Susceptibility and Clinical Phenotypes of Staphylococcus argenteus Isolated from Clinical Specimens

Recently, Staphylococcus argenteus, previously indistinguishable from Staphylococcus aureus, has been recognized as a clinically relevant microorganism because of mass spectrometry. However, despite its clinical significance, limited information is available on S. argenteus. This study evaluated the antimicrobial susceptibility and clinical phenotypes of S. argenteus isolated from clinical specimens. This single-center, retrospective study analyzed cases wherein S. argenteus was detected in clinical specimens obtained at Nagoya City University East Medical Center between April 2023 and April 2024. The organism was identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Patient data, including clinical outcomes, were collected and reviewed to classify cases as infections or colonization. S. argenteus was isolated from 23 specimens of 21 patients, with sputum being the most common source (78.3%). Sixty-seven percent of isolates were susceptible to penicillin; 95.2% to erythromycin; and 100% to oxacillin, clindamycin, sulfamethoxazole-trimethoprim, vancomycin, and teicoplanin. Thirteen cases of infection were recorded; pneumonia was the predominant diagnosis (11 cases) in these cases, followed by otitis externa and vertebral osteomyelitis. Most patients were successfully treated with antibiotics, and only one died of S. argenteus pneumonia.