, 2010). However, culture of the valve tissue itself was not necessarily more effective, whereas molecular methods were more successful at identifying a causative microorganism. The identification by broad range PCR and subsequent sequencing of Protein Tyrosine Kinase inhibitor heart valve material could be confirmed by FISH analysis
showing extensive biofilms in culture-negative endocarditis cases (Mallmann et al., 2009). As FISH targets ribosomal RNA, this molecular method also indicates recent metabolic activity of the bacteria. For subacute bacterial endocarditis, which may be present for weeks or even months before being diagnosed, an antibody response may be helpful (Kjerulf et al., 1998a, b), whereas in acute bacterial endocarditis caused by Streptococcus pneumonia or S. aureus, an antibody response is not yet detectable (Kjerulf et al., 1993, 1998a, b). Antibody response has also been useful for diagnosis of biofilm
infections caused by other bacteria than P. aeruginosa (e.g. Burkholderia, Achromobacter, and Stenotrophomonas) in CF (Høiby & Pressler, 2006). Diagnosis of prosthetic joint infection in orthopedics Lumacaftor is another example where culture is suspected of producing a high rate of false negative results and suggests that infection might be commonly misdiagnosed as ‘aseptic loosening’ (Tunney et al., 1998). Even in cases when the surface is sampled directly by swabbing, it has been shown that bacteria may be extremely hard to detach (Passerini et al., 1992; Kobayashi et al., 2007, 2009; Bjerkan et al., 2009). Low intensity ultrasonication by ultrasonic bath with subsequent culturing of the sonicate has been shown to increase culture sensitivity. Data from 195 retrieved prostheses collated by Nelson (Nelson et al., 2005) from multiple sources (Gristina et al., 1985; Gristina & Costerton (1985); Dobbins et al., 1988; Moussa et al., 1997; Tunney et al., 1998) and grouped here for statistical comparison of proportions (MedCalc®)
showed that ultrasonication significantly increased positive culture rate from 14% to 35% (P < 0.001). A later study of 404 patients reported a similar trend: preultrasonication increased culture positivity relative to tissue culture from 61% to 79% (Trampuz et al., 2007) but offered no statistically significant Calpain increase in sensitivity for synovial fluid. The interpretation is that sensitivity of culture is increased because ultrasonication breaks up attached biofilm and releases bacteria that would otherwise remain attached to the prosthesis. However, it is possible that sonication might also affect the physiology of released bacteria, converting them to the more readily culturable planktonic phenotype, in addition to a dilution effect on any residual antibiotics, because sonication is performed with the prosthesis immersed in a saline buffer.
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