Antimicrobial-resistant Pseudomonas aeruginosa and Acinetobacter baumannii From Patients With Hospital-acquired or Ventilator-associated Pneumonia in Vietnam

Abstract Purpose Multidrug-resistant bacterial pathogens are becoming a significant problem worldwide. Acinetobacter baumannii and Pseudomonas aeruginosa are problematic multidrug-resistant pathogens. This multicenter study in Vietnam determined the level of resistance to antimicrobial agents used to treat A baumannii and P aeruginosa infections in this country. Methods Five medical centers in Vietnam provided 529 P aeruginosa and 971 Acinetobacter species (904 A baumannii ) isolates from patients with hospital-acquired or ventilator-associated pneumonia from 2012 to 2014. A central laboratory verified identification of the isolates and performed susceptibility testing using Clinical and Laboratory Standards Institute methods. Findings Resistance to cephalosporins, β-lactam/β-lactamase inhibitors, carbapenems, and fluoroquinolones was >90% against A baumannii . Aminoglycosides had only slightly better activity, with amikacin resistance >80%. Only colistin (MIC 90 , ≤0.25 mg/L) and tigecycline (MIC 90 , 4 mg/L) had appreciable activity against A baumannii . Similar activity was observed among the β-lactams tested against P aeruginosa . Cefepime demonstrated the highest activity (60.1% susceptible), which was similar to doripenem (58.6% susceptible), the most active carbapenem tested. Amikacin was the most active aminoglycoside tested against P aeruginosa , with susceptibility of 81.7% compared with tobramycin (58.0%) and gentamicin (56.5%). Fluoroquinolones had limited activity against P aeruginosa with susceptibility to ciprofloxacin (55.0%). All P aeruginosa isolates had colistin MIC values ≤2 mg/L. Implications The data from this 3-year longitudinal study in Vietnam demonstrate that 2 of the most common nonfermentative gram-negative pathogens associated with hospital-acquired and ventilator-associated pneumonia are significantly resistant to most of the available treatment options and require combination therapies unless new antimicrobial agents become available.