Abstract & Overview
BACKGROUND: The polymer matrix of Klebsiella pneumoniae biofilm contributes to its resistance to a broad spectrum of antibiotics and poses a significant public health threat. OBJECTIVES: The present study aims to use hydrogen peroxide (H2O2) sub-minimum inhibitory concentrations (sub-MICs) to improve cefotaxime efficiency against cefotaxime-resistant K. pneumoniae (CRKP) by disrupting the biofilm polymer matrix. Objectives. The present study aims to determine whether sub-MICs of hydrogen peroxide (H2O2) can enhance the efficacy of cefotaxime against CRKP by disrupting the biofilm polymer matrix. MATERIAL AND METHODS: Klebsiella pneumoniae was isolated from 140 burn wound samples. The effect of cefotaxime and sub-MICs of H2O2 on biofilm formation by pretreated K. pneumoniae was evaluated. A scanning electron microscope (SEM) was used to examine the effect of H2O2 sub-MICs on the biofilm matrix. The synergistic effect of H2O2 sub-MICs on the susceptibility of CRKP to cefotaxime and on the structure of the biofilm polymer matrix was also assessed. RESULTS: A moderately high incidence of wound infections caused by CRKP was observed. A statistically significant negative correlation was found between biofilm formation and bacterial susceptibility to cefotaxime (r = -0.501, p = 0.024). Treatment with various sub-MICs of H2O2 and cefotaxime reduced biofilm formation on polystyrene surfaces by the K. pneumoniae Kp10 isolate. Specifically, exposure to H2O2 at 1/8 MIC induced the formation of pores and channels within the biofilm matrix, resulting in a looser biofilm structure. A synergistic effect (fractional inhibitory concentration (FIC) index ≤ 0.5) was observed, where sub-MICs of H2O2 decreased the MIC of cefotaxime against Kp10 from 1,000 μg/mL to 250 μg/mL at ½ and ¼ MIC of H2O2, and produced a strong additive effect with a reduction to 500 μg/mL at other sub-MICs. The combination of H2O2 sub-MICs and cefotaxime was more effective in reducing biofilm formation than either agent used alone. CONCLUSIONS: Sub-minimum inhibitory concentrations of H2O2 exhibited synergistic to strongly additive effects in enhancing the antibacterial activity of cefotaxime against CRKP and in reducing biofilm formation by the K. pneumoniae Kp10 isolate. This effect appears to be mediated by disruption of the biofilm polymer matrix, which may contribute to improved infection control.