To report the treatment process of a patient with multiple resistant Pseudomonas aeruginosa to guide antibiotic drug selection and dosage with antimicrobial susceptibility testing and precision therapeutic drug monitoring (TDM).

The treatment process of one elderly with multidrug-resistant Pseudomonas aeruginosa (MDRPA) bloodstream infection caused by a cerebral abscess was reported. During the treatment process, empirical therapy with ceftazidime-avibactam (CAZ-AVI) was initially used.

The patient showed an improvement in her clinical symptoms. However, subsequent bacterial susceptibility testing revealed resistance to CAZ-AVI. Considering the low clinical tolerance for treatment modification, the therapy was switched to the sensitive agent polymyxin B at a maintenance dose of 1 mg/kg. TDM indicated an achieved AUC_{24 h, ss} of 65.5 mg·h/L. However, after 6 days of treatment, there was no improvement in clinical symptoms. Faced with this complex situation, a collaborative effort among the clinical physician, pharmacologist, and microbiologist led to an increase in the polymyxin B dose to 1.4 mg/kg, resulting in an AUC_{24 h, ss} of 98.6 mg·h/L. Ultimately, the treatment was successful, and the pathogen was eradicated.

Within the framework of scientific and regulated medication management, a collaborative multidisciplinary treatment (MDT) approach enhances the patient's rehabilitation process. The doctor's clinical expertise, guidance from TDM and pharmacokinetics/pharmacodynamics experts, and the antimicrobial susceptibility results provided by the clinical microbiology laboratory collectively inform the treatment direction.