Detection of viable but non-culturable staphylococci in biofilms from central venous catheters negative on standard microbiological assays.

Viable bacteria were sought in 44 Maki-negative biofilms from central venous catheters (CVCs) using epifluorescence microscopy after live/dead staining. Thirty (77%) samples contained viable but non-culturable (VBNC) cells; the majority were positive on real-time PCR specific for Staphylococcus epidermidis (one also for Staphylococcus aureus). Viable cells were significantly (p<0.01) associated with CVCs from febrile patients, three of whom showed S. epidermidis-positive blood cultures, suggesting that CVC-associated biofilms can be reservoirs for staphylococci in the VBNC state. The possible role of VBNC staphylococci in persistent infections related to medical devices requires further investigation.