Native valve endocarditis due to Staphylococcus kloosii: a brief report

We describe the first reported case of native valve endocarditis (NVE) caused by Staphylococcus kloosii and highlight the clinical significance of coagulase-negative staphylococci (CoNS) isolated from blood cultures. We report a case of a 70-year-old male with multiple comorbidities presenting with progressive heart failure, who was managed across three hospitals. Clinical records, imaging findings, and microbiological investigations were reviewed. Retrospective analysis of blood cultures from prior admissions at referring institutions was undertaken. Intra-operative findings during mitral valve replacement revealed vegetations and chordal rupture. S. kloosii was isolated from excised valve tissue after prolonged incubation and confirmed by MALDI-TOF and 16S rRNA sequencing. Blood cultures obtained during earlier admissions at two separate hospitals had also yielded S. kloosii but were interpreted as contaminants. The patient received targeted antimicrobial therapy following surgery and completed a 6-week treatment course, with a favourable outcome despite a drug-related adverse event. This case demonstrates that rare CoNS species such as S. kloosii can cause invasive infection, including NVE. Repeated isolation across multiple healthcare encounters should prompt careful clinical evaluation to avoid delayed diagnosis and improve outcomes.