Amoxicillin and specific bacteriophage can be used together for eradication of biofilm of Klebsiella pneumoniae B5055

Despite the efficacy of antibiotics as well as bacteriophages in treatment of bacterial infections, their role in treatment of biofilm associated infections is still under consideration especially in case of older biofilms. Here, efficacy of bacteriophage alone or in combination with amoxicillin, for eradication of biofilm of Klebsiella pneumoniae B5055 has been assessed. Planktonic cells as well as biofilm of K. pneumoniae B5055 grown in 96-well microtiter plates were exposed to bacteriophage and amoxicillin at various Multiplicity of Infections (MoIs) as well as at three different antibiotic concentrations (512, 256 and 128 μg/ml), respectively. After exposure to 256 μg/ml (MIC) of amoxicillin, bacterial load of planktonic culture as well as 1-day-old biofilm was reduced by a log factor of 4.1 ± 0.31 (P = 0.008) and 1.24 ± 0.27 (P < 0.05), respectively but reduction in the bacterial load of mature biofilm (8-day-old) was insignificant (P = 0.23). When 8-day-old biofilm was exposed to higher antibiotic concentration (512 μg/ml) or phage alone (MoI = 0.01) a log reduction of 2.97 ± 0.11 (P = 0.182) and 3.51 ± 0.19 (P = 0.073), respectively was observed. While on exposing to a combination of both the amoxicillin and phage, a significant reduction (P < 0.01) in bacterial load of the biofilm was seen. Hence, when antibiotic was used in combination with specific bacteriophage a greater destruction of the biofilm structure suggested that the phages could be used successfully along with antibiotic therapy. An added advantage of the combination therapy would be its ability to check formation of resistant mutants that otherwise develop easily upon using phage or antibiotic alone.