Effective minocycline treatment enhances clinical Klebsiella pneumoniae infections: Investigation of biofilm resistance mutations and antimicrobial efficacy in pediatric infections.

The extensive use of antibacterial agent has led to a steady decline in the clinical exposure of Klebsiella pneumoniae to carbapenems (CPM), creating considerable obstacles for infection control and clinical disinfection. K. pneumoniae utilizes the development of dense biofilms and overexpression of efflux pumps to circumvent the detrimental properties of CPM. Minocycline (MCL) is a promising antibacterial agent that reduces proton motive forces and increases membrane permeability. This study demonstrated the synergistic antibacterial effect of MCL and CPM, which significantly lowered the MIC of CPM-resistant K. pneumoniae. Importantly, using crystal violet and live/dead staining, we found that MCL markedly improved the anti-biofilm efficacy of CPM. Studies assessing reactive oxygen species, alkaline phosphatase leakage, membrane permeability, and RT-PCR indicated that the combination of MCL and CPM induced oxidative stress, enhanced the permeability of K. pneumoniae membrane, and suppressed the overexpression of the efflux pump genes oqxA and oqxB. Additionally, we performed surface disinfection trials on medicinal tools to replicate clinical settings, revealing that MCL and CPM significantly decreased the bacterial burden by 3 log CFU/mL. Furthermore, findings from the resistance mutation frequency assays demonstrated that the combinational therapy (MCL + CPM) diminished the emergence of the K. pneumoniae population. Overall, MCL can function as an ancillary agent, augmenting the biofilm efficacy of CPM and attenuating the emergence of resistance mutation, thus prolonging the efficacy of CPM.