, 2000; Döring & Høiby, 2004). Another example of recalcitrance to antibiotic treatment is chronic OM, which is distinguished from acute OM. Two types of chronic infection profiles are described:

OM with effusion (OME) where the effusion persists for > 3 months, or, a recurrent infection often referred to as recurrent acute OM or RAOM, www.selleckchem.com/products/VX-809.html where fluid resolves between recurrent events (Hall-Stoodley et al., 2006; Post et al., 2007). Both types are consistent with other BAI, exhibiting recurrent acute symptoms after repeated cycles of antibiotic therapy without eradication of the underlying infection. This is thought to be due to the release of planktonic bacterial cells from biofilms and their susceptibility to antibiotic treatment when microorganisms are not aggregated (Costerton et al., 1999), while the biofilm causes a persistent infection that elicits a low grade inflammatory response. Evidence that recurrent OM, in addition to OME, is a BAI was shown using both immunofluorescent methods with pathogen-specific antibodies and FISH pathogen-specific 16S rRNA gene probes to demonstrate bacterial pathogens attached to the middle ear mucosa in children having tympanostomy tube placement for the treatment of recurrent OM in addition to OME (Hall-Stoodley et al., 2006). Criteria 4 and 5 illustrate that antimicrobial

recalcitrance or evidence of greater tolerance Decitabine nmr is an important indication of BAI and may be linked to the failure of culture to identify a pathogen in fluid samples. Criterion 5 also suggests that other diagnostic guidelines are needed if BAI do not PAK6 yield culture-positive results. In CF, three additional criteria are used to diagnose biofilm infection: (1) continued isolation of P. aeruginosa from sputum for at least 6 months, (2) detection of the alginate producing mucoid phenotype of P. aeruginosa, and (3) an

increase in anti-P. aeruginosa antibodies (Pressler et al., 2006, 2009; Proesmans et al., 2006). Reliance on culture as the ‘gold standard’ of medical microbiology exclusively for the identification of bacterial pathogens as a diagnostic criterion in clinical laboratories is not clear-cut with BAI. Numerous publications indicate a discrepancy between culture and molecular diagnostic methods. In OME, culture identifies a pathogen around 25–30% of the time, while culture-independent methods such as PCR and/or FISH identify pathogens 80–100% of the time (Post et al., 1995; Hall-Stoodley et al., 2006). This discrepancy was not because of the amplification of DNA from dead bacteria (Aul et al., 1998; Dingman et al., 1998) and contrasts with acute OM where culture successfully identifies a pathogen over 90% of the time (Post et al., 1995; Rayner et al., 1998). Infectious endocarditis also has a proportion of cases (as much as one-third) that fail to grow bacteria in culture.