S. pneumoniae, M. catarrhalis and H. influenzae are the most common pathogens implicated in OME, and all are capable of forming biofilms [33,42]. However, rather than focusing just on those three bacteria, this study cultured effusions on a wide range of different media for prolonged time periods in order to capture as many isolates as possible. Interestingly, coagulase negative staphylococci (CoNS), Veillonella spp. and S. aureus were the three commonest pathogens isolated in this study. CoNS were long thought to be non-pathogenic commensals, but with the recognition of their biofilm-forming capacity have emerged as the leading cause of biomaterials-related infection [43,43]. S. lugdunensis, isolated here on three occasions, in particular has been implicated in endocarditis, wound infection, and implant-related infection as well as otitis media, behaving more like S. aureus than other CoNS [45]. Other CoNS have also been previously implicated in otitis media, with a recent study finding that they account for 60% of bacteria isolated from OME [46,47]. Veillonella is a Gram-negative anaerobe that inhabits the mouth and upper respiratory tract, forms biofilms [48] and has previously been found in middle ear disease [49,50]. S. aureus also forms biofilms and has been identified in middle ear disease [51,52]. Although most of the bacteria in Table 2 have previously been isolated in middle ear disease, to the best of the authors’ knowledge Flavimonas oryzihabitans, Vibrio metschnikovii and Gemella haemolysans have not been implicated previously.
bacteria
three
commonest pathogens
three
S. lugdunensis
isolated
three occasions
occasions
bacteria isolated from OME
CoNS
60%
%