Clinical significance of coagulase-negative staphylococci other than S. epidermidis blood stream isolates at a tertiary care hospital.

PURPOSE: We retrospectively evaluated blood culture (BC) isolates of coagulase-negative staphylococci other than Staphylococcus epidermidis (NonSe-CoNS) for clinical relevance at a tertiary care hospital in Germany from January 2011 to September 2015.

METHODS: Clinical data were correlated to microbiological results based on medical records. Infection was considered likely if (1) no other infection and (2) two or more isolates of the same species were present and (3) symptoms ameliorated after therapy. Infection was considered possible if a foreign body was present and (1) and (3) were fulfilled. All the other cases were considered contaminations.

RESULTS: 313 patients with blood cultures positive for NonSe-CoNS were identified. 61 patients were excluded, either because of missing data or multiple pathogens in the same blood culture. Of the remaining 252 patients, 58 (23 %) were classified as possible (n = 32) or likely (n = 26) infections. S. haemolyticus was the most frequent isolate (infection: n = 28), followed by S. hominis (n = 13), S. capitis (n = 12), and S. lugdunensis (n = 3). One patient died from NonSe-CoNS infection. The source of infection in the majority of patients was foreign bodies (n = 43), and endocarditis was present in six cases. Staphylococci always considered contaminations were: S. auricularis, S. caprae, S. schleiferi, S. pettenkoferi, S. saccharolyticus, and S. simulans. The growth of NonSe-CoNS in the anaerobic BC bottle only and a time to positivity >36 h were associated with contaminations.

CONCLUSIONS: One out of four NonSe-CoNS isolates was clinically relevant in our cohort, where S. haemolyticus, S. capitis, S. hominis, and S. lugdunensis contributed to 96.6 % of all relevant infections.