Levofloxacin-resistant Stenotrophomonas maltophilia: risk factors and antibiotic susceptibility patterns in hospitalized patients

Abstract

Levofloxacin has been considered as an alternative treatment for Stenotrophomonas maltophilia infection. However, levofloxacin-resistant S.maltophilia (LRSM) are emerging worldwide. To investigate LRSM risk factors in hospitalized patients and to determine antibiotic susceptibility patterns of LRSM isolates. In a retrospective matched case-control-control study, LRSM patients (the case group) were compared with two control groups: levofloxacin-susceptible S.maltophilia (LSSM) patients (control group A) and non-S.maltophilia-infected patients (control group B). Conditional logistic regression was used to analyse risk factors for LRSM occurrence. Tigecycline, ceftazidime, colistin, and trimethoprim/sulfamethoxazole (TMP/SMX) susceptibilities in collected LRSM clinical isolates were determined. A total of 105 LRSM, 105 LSSM, and 105 non-S.maltophilia-infected patients were analysed. The first multivariate analysis (cases vs group A) revealed that previous fluoroquinolones use was significantly associated with LRSM occurrence, and the second multivariate analysis (cases vs group B) revealed that previous fluoroquinolone use, previous intensive care unit stay, and the number of previous exposures to different classes of antibiotics were significantly associated with LRSM occurrence. Of all the LRSM isolates tested for antibiotic susceptibility, ceftazidime, TMP/SMX, tigecycline, and colistin resistance rates were 42.0, 99.0, 78.0, and 40.0%, respectively. LRSM antibiotic susceptibility patterns revealed multiple-drug resistance, which further limits treatment options for clinicians. To reduce LRSM occurrence, proper use of antibiotics, especially fluoroquinolones, is mandatory.