Synergistic effect of low-frequency ultrasound and antibiotics on the treatment of Klebsiella pneumoniae pneumonia in mice

Abstract

The antibiotic-resistant Klebsiella pneumoniae (Kp) has become a significant crisis in treating pneumonia. Low-frequency ultrasound (LFU) is promising to overcome the obstacles. Mice were infected with bioluminescent Kp Xen39 by intratracheal injection to study the therapeutic effect of LFU in combination with antibiotics. The counts per second (CPS) were assessed with an animal biophoton imaging system. Bacterial clearance, histopathology, and the concentrations of cytokines were determined to evaluate the therapeutic effect. LC-MS/MS was used to detect the distribution of antibiotics in the lung and plasma. LFU in combination with meropenem (MEM) or amikacin (AMK) significantly improved the behavioural state of mice. The CPS of the LFU combination group were more significantly decreased compared with those of the antibiotic alone groups. The average colony-forming units of lung tissue in the LFU combination groups were also lower than those of the antibiotic groups. Although no significant changes of cytokines (IL-6 and TNF-α) in plasma and bronchoalveolar lavage fluid were observed, LFU in combination with antibiotics showed less inflammatory damage from histopathological results compared with the antibiotic-alone groups. Moreover, 10 min of LFU treatment promoted the distribution of MEM and AMK in mouse lung tissue at 60 and 30 min, respectively, after dosage. LFU could enhance the effectiveness of MEM and AMK in the treatment of Kp-induced pneumonia, which might be attributed to the fact that LFU could promote the distribution of antibiotics in lung tissue and reduce inflammatory injury.

FIGURE 1

Schematic diagram of the mouse experiment process.

FIGURE 2

Representative bioluminescence monitoring images and CPS quantification analysis. (A) Representative bioluminescence monitoring images of Kp Xen39. The colour bar on the right represents the radiation intensity, and the brighter the colour, the more bacteria. (B) CPS quantification analysis and time‐varying trend of each group (means ± SD; n = 10).

FIGURE 3

Total bacterial counts from the right lung homogenate of mice. (n = 10; *p < 0.05; **p < 0.01).

FIGURE 4

Lung histopathology and injury scores. (A) Representative H&E stained sections of mouse left lung. (B) Histopathological injure scores. (means ± SD; n = 10; *p < 0.05; **p < 0.01).

FIGURE 5

Cytokine concentrations (IL‐6 and TNF‐α) in plasma and BALF (means ± SD; n = 10; **p < 0.01).

FIGURE 6

The concentration of antibiotics in plasm and homogenate (means ± SD; n = 6; *p < 0.05; **p < 0.01).