Antimicrobial Susceptibility of Acinetobacter calcoaceticus-Acinetobacter baumannii Complex and Stenotrophomonas maltophilia Clinical Isolates: Results From the SENTRY Antimicrobial Surveillance Program (1997-2016).

Background: Acinetobacter calcoaceticus-A. baumannii ( Acb ) complex and Stenotrophomonas maltophilia represent frequent causes of hospital-acquired infections. We evaluated the frequency and resistance rates of Acb complex and S. maltophilia isolates from medical centers enrolled in the SENTRY Program.

Methods: A total of 13 752 Acb complex and 6467 S. maltophilia isolates were forwarded to a monitoring laboratory by 259 participating sites from the Asia-Pacific region, Latin America, Europe, and North America between 1997 and 2016. Confirmation of species identification and antimicrobial susceptibility testing were performed using conventional methods and/or matrix-assisted laser desorption ionization-time of flight mass spectrometry and the broth microdilution method, respectively. Antimicrobial susceptibility results were interpreted by CLSI and EUCAST 2018 criteria.

Results: Acb complex and S. maltophilia were most frequently isolated from patients hospitalized with pneumonia (42.9% and 55.8%, respectively) and bloodstream infections (37.3% and 33.8%, respectively). Colistin and minocycline were the most active agents against Acb complex (colistin MIC50/90 , ≤0.5/2 mg/L; 95.9% susceptible) and S. maltophilia (minocycline MIC50/90 , ≤1/2 mg/L; 99.5% susceptible) isolates, respectively. Important temporal decreases in susceptibility rates among Acb complex isolates were observed for all antimicrobial agents in all regions. Rates of extensively drug-resistant Acb complex rates were highest in Europe (66.4%), followed by Latin America (61.5%), Asia-Pacific (56.9%), and North America (38.8%). Among S. maltophilia isolates, overall trimethoprim-sulfamethoxazole (TMP-SMX) susceptibility rates decreased from 97.2% in 2001-2004 to 95.7% in 2013-2016, but varied according to the geographic region.

Conclusions: We observed important reductions of susceptibility rates to all antimicrobial agents among Acb complex isolates obtained from all geographic regions. In contrast, resistance rates to TMP-SMX among S. maltophilia isolates remained low and relatively stable during the study period.