Trends in Stenotrophomonas maltophilia antibiotic resistance rates in the United States Veterans Affairs Health System

Abstract

Introduction.Stenotrophomonas maltophiliais an important multidrug-resistant Gram-negative pathogen. While largely a hospital-acquired pathogen, there have been increasing reports of the pathogen in the community.Gap Statement. Trends inS. maltophiliaprevalence and resistance rates that include outpatient isolates are unknown.Aim. We described recent trends in prevalence and resistance ofS. maltophiliain the national Veterans Affairs (VA) Healthcare system.Methodology. The study identified positiveS. maltophiliaclinical cultures among VA adult patients from 2010 to 2018 across all VA hospitals, long-term care facilities/units, and outpatient settings. AnnualS. maltophiliaresistance rates were evaluated. Multidrug resistant (MDR) was defined as resistance to sulfamethoxazole/trimethoprim (SMX/TMP) and minocycline or levofloxacin. Time trends were assessed with regression analyses to estimate annual average percent changes (AAPC) with 95 % confidence intervals using Joinpoint software.Results. Over the 9 year study period, 18 285 S.maltophiliacultures were identified (57 % hospital, 3 % long-term care, 40 % outpatient). The most common source ofS. maltophiliacultures were respiratory cultures (34.6 %) followed by urine cultures (30.4 %). In VA hospitals and long-term care facilities, the number ofS. maltophiliacultures decreased significantly (by 5.4% and 8.4 % per year respectively). Overall, 3.1 % of isolates were MDR which remained stable over the study period. Resistance to other antibiotics assessed mostly remained stable, except SMX/TMP resistance decreased significantly by 8.5 % (2010, 15 %; 2018, 6 %) per year in VA hospitals.Conclusion. While previous work has recognizedS. maltophiliaas primarily a nosocomial pathogen, the present study found that 40 % of cultures collected were among outpatients. Between 2010 and 2018, the number of positiveS. maltophiliacultures decreased significantly in the national VA Healthcare System. Resistance to SMX/TMP decreased over the study period in VA hospitals and now more closely reflects previously reported resistance rates worldwide (0–10 %). MDRS. maltophiliaremained stable and low in the national VA Healthcare System.