Inhibitory Effect of Lactobacilli Filtrate on Klebsiella Pneumoniae Biofilm


ABSTRACT:BACKGROUND:The formation of biofilms by K. pneumoniae is thought to protect the bacteria from antibiotics since these entities are highly resistant to such antimicrobial agents.OBJECTIVE:Investigating the role of Lactobacillus spp. supernatant in eliminating K. pneumoniae biofilms.METHODS:Three hundred and twelve specimens of urine, wounds and sputum were collected from patients attending five hospitals in Baghdad. All specimens were identified using biochemical tests and Api 20 E system. The ability of K. pneumoniae isolates to produce biofilm were evaluated using crystal violet staining technique in pre-sterilized 96-well polystyrene microtiter plates. The effect of MIC of Amikacin and Gentamicin was assessed on biofilm. The ability of acid and alkaline supernatants of Lactobacillus acidophilus and L. fermentum to inhibit planktonic as well as biofilm of K. pneumoniae K14, K15, K17 and K19 isolates were separately tested.RESULTS:Twenty two (39.29%) K. pneumoniae isolates were considered as high biofilm producers. Moreover, K. pnumoniae isolates; K14, K15, K17 and K19 produced the thickest biofilm. All biofilms treated with Amikacin and Gentamicin developed a presence of live cells when cultured on plate count agar. Neither neutralized supernatant of Lactobacillus acidophilus (Lb1) and L. fermentum (Lb2) nor sterile MRS broth has an effect on planktonic K. pneumoniae K14, K15, K17 and K19 isolates. Yet, results showed that lactobacilli acid supernatant developed a marked inhibitory effect. Significant differences (P<0.05) were found in O.D. and viable count between pre and post treatment of K. pneumoniae K14, K15, K17 and K19 biofilms with acid supernatants of Lb1 or Lb2. Unlike the Amikacin and Gentamicin treatment which left live bacterial cells, Lactobacillus supernatant left no live cells except for two cases; Lb1 against K17 and Lb2 against K15.CONCLUSION:Lactobacillus supernatant is a potent antimicrobial agent against K. pneumoniae biofilms