Characterization of coagulase-negative staphylococci isolated from hospital indoor air and a comparative analysis between airborne and inpatient isolates of Staphylococcus epidermidis.

A total of 108 coagulase-negative staphylococci (CoNS) were collected from hospital indoor air. The majority of the isolates were able to produce biofilms and displayed multiresistance profiles. The most frequent species identified were Staphylococcus epidermidis (n=27) and Staphylococcus haemolyticus (n=17). Potential virulence traits (icaAD, aap, hld, atlE and sesB) and genotypic profiles were compared for S. epidermidis isolates from indoor air (n=27) and from patients (n=26) who had been admitted to the hospital 8-34 months after air sampling. Overall, the virulence factors tested were more frequently found among S. epidermidis recovered from clinical origin than from air sources (P=0.003). Indeed, the group of patient isolates exhibited superior ability to accumulate biofilms (P<0.0001). Despite this, genotyping using PFGE revealed that identical clones of S. epidermidis could be recovered from both patient and indoor air samples. In addition, some airborne isolates displayed virulence profiles and levels of biofilm accumulation similar to those found in patient isolates. Therefore, further studies are necessary to clarify the importance of hospital indoor air as a route of transmission for CoNS isolates (mainly S. epidermidis).