Treatment of Resistant Pseudomonas Aeruginosa Infections

Introduction to Treatment Options

The International Society for Antimicrobial Chemotherapy recommends ceftolozane/tazobactam or ceftazidime/avibactam as the first-line treatment for invasive infections caused by difficult-to-treat Pseudomonas aeruginosa (DTR-PA) based on preclinical and clinical data 1
The European Respiratory Society suggests that imipenem/cilastatin-relebactam and cefiderocol may also be considered as potential alternative treatments for DTR-PA infections 1
Colistin-based therapy is another option for the treatment of DTR-PA infections 1

Ciprofloxacin is the optimal oral anti-pseudomonal agent, with a recommended high dose of 750 mg every 12 hours 3
However, it is essential to note that the resistance rate of Pseudomonas aeruginosa to ciprofloxacin is increasing in some European countries 3
Levofloxacin has recently been approved for use against P. aeruginosa (750 mg every 24 hours), but clinical experience is limited 3

Combination therapy is not usually the first choice for the treatment of DTR-PA infections but may be considered on a case-by-case basis, particularly in consultation with an infectious disease specialist 2
A combination regimen that includes fosfomycin as an adjunctive therapy may be considered 2
Intravenous administration of antibiotics is crucial for critically ill patients (ICU admission) 3

Oral administration is recommended when the patient is able to take oral medications 3, 4
Intravenous administration should be used when oral intake is not possible, and switched to oral administration when the patient is clinically stable (after 3-5 days of hospitalization) 3, 4
The treatment duration for antibiotics in COPD patients should be maintained for an average of 7-10 days 3
A 5-day course of levofloxacin or moxifloxacin has been shown to have similar efficacy to a 10-day course of beta-lactam therapy 3

Approximately 10-20% of patients do not respond to empirical antibiotic therapy 3
The cause of treatment failure may be an initial infection with microorganisms (P. aeruginosa, MRSA, Acinetobacter, etc.) not covered by the empirical regimen 3
In cases of treatment failure, it is recommended to change to an antibiotic with good coverage against P. aeruginosa, antibiotic-resistant S. pneumoniae, and non-fermenting bacteria, and adjust the new antibiotic therapy according to microbiological results 5

DTR-PA is defined as a strain that is non-susceptible to all of ceftazidime, cefepime, piperacillin/tazobactam, aztreonam, imipenem/cilastatin, meropenem, levofloxacin, and ciprofloxacin 1, 2
Antibiotics should be selected based on the microbial resistance pattern, which is strongly recommended 6