To observe the clinical efficacy and safety of polymyxin B injection combined with sitafloxacin tablets in the treatment of hospital-acquired pneumonia (HAP) caused by extensively drug-resistant Pseudomonas aeruginosa.

Patients with pandrug-resistant pseudomonas aeruginosa (PDR-PA) pneumonia admitted to our hospital were enrolled. According to treatment regimen, patients were divided into control group and treatment group. Patients in the control group received polymyxin B injection at an initial dose of 2.0-2.5 mg·kg^-1, followed by a maintenance dose of 1.25-1.5 mg·kg^-1 every 12 h after the loading dose. Patients in the treatment group received additional oral sitafloxacin tablets at 50-100 mg twice daily on the basis of the above regimen. The duration of antibacterial treatment for both groups was 7 days in principle, with a maximum of 14 days. Clinical efficacy, bacterial clearance rate, inflammatory markers, arterial blood gas and oxygenation parameters, prognosis, and safety profiles were compared between two groups.

A total of 128 patients were included in this study, with 64 cases in each group. After treatment, the total effective rates in the control group and the treatment group were 76.56% (49 cases/64 cases) and 95.31% (61 cases/64 cases), showing a statistically significant difference (P<0.05). After treatment, the total bacterial clearance rates in control and treatment groups were were 73.44% (47 cases/64 cases) and 93.75% (60 cases/64 cases), respectively; the serum levels of procalcitonin (PCT) were (1.42±0.31) and (0.81±0.18) ng·mL^-1, respectively; C-reactive protein (CRP) were (68.14±15.62) and (38.27±12.46) mg·L^-1, respectively; and interleukin-6 (IL-6) were (61.73±14.85) and (38.92±11.77) pg·mL^-1, respectively; the arterial partial pressure of oxygen (PaO₂) were (75.36±7.15) and (88.57±6.93) mmHg, respectively; the arterial partial pressure of carbon dioxide (PaCO₂) were (45.27±4.86) and (39.68±4.25) mmHg, respectively; and the oxygenation index (PaO₂/FiO₂) were 236.48±28.51 and 278.36±31.22, respectively. All of these indicators in treatment group showed statistically significant differences compared to control group (all P<0.05). The 28-day all-cause mortality rates of the control group and the treatment group were 10.94% (7 cases/64 cases) and 4.69% (3 cases/64 cases), respectively; and the length of hospital stay were (15.82±4.27) and (14.97±3.58) d, respectively; with no significant differences between the two groups (all P>0.05). The incidences of total adverse drug reactions in the treatment group and the control group were 18.75% (12 cases/64 cases) and 25.00% (16 cases /64 cases), respectively, with no statistically significant difference between the two groups (P>0.05).

Polymyxin B injection combined with sitafloxacin tablets significantly improves bacterial clearance, reduces inflammatory response, and enhances oxygenation in patients with xDR-PA HAP, while maintaining good safety, indicating its potential clinical utility.