1Isolate related by RFLP (Figure 1) 2nsGPL genes: gtfA, rtfA and mtfC 3 ser2 genes: mdhtA, merA and mtfF 41591 and 1655 had a weak PCR product for mtfC. Sequencing showed a product with few bases different from AF125999 TMC724/ATCC 25291). The PCR product of #1591 was identical to the sequence of the mtfC gene of M. avium 104 Biofilm forming isolates are marked in bold typing. Discussion In this study, a method suitable for screening a large number of M. avium isolates for biofilm formation was established. Ninety-seven HDAC inhibitor isolates of M. avium subsp. avium and
M. avium subsp. hominissuis originating from birds, swine and humans were examined for their biofilm forming abilities. To our knowledge, this is the first time a large number of such isolates from different hosts have been tested for biofilm formation. Nine isolates from swine formed biofilm, none of the isolates from humans or birds did. The optimised method was easy to perform, can be adapted to other test-conditions Wnt activity and gave clear and consistent results. A high and consistent biofilm-production was seen only when using Middlebrook 7H9, while no biofilm was detected in water. Biofilm forming abilities
did not correlate with RFLP-profile, hsp65 sequevar, colony morphology or with the presence of the tested GPL biosynthesis genes. Water has been described as the best medium for evaluation of biofilm formation [30, 42]. Williams et al used autoclaved potable water for biofilm quantification by CFU count and imaging , while Geier et al. used MQ water . However, our isolates did not make biofilm in water, even though different types of water and water from different sources like distilled, potable and lake water was included. This discrepancy between earlier studies and the present study can be due to different isolates tested
or to other conditions in the experimental set-up. Water is not a standardised medium, and the content of ions, organic matter and the pH will vary Pitavastatin depending on local factors. Interleukin-2 receptor Carter et al. demonstrated the effect of different ions and carbon sources on biofilm formation . To test a medium containing different salts and glucose, we tested our panel of isolates in Hanks’s balanced salt solution, which has been described as potential biofilm media for M. avium [33, 42]. However in our hands, none of the isolates formed biofilm in Hanks’. In the present study, few isolates formed biofilm. The testing is performed under laboratory conditions, and cannot be directly transferred to bacterial behaviour in the environment.