Risk factors and molecular mechanisms associated with trimethoprim-sulfamethoxazole resistance in Stenotrophomonas maltophilia in Mexico

Sandra Abril Herrera-Heredia, César Pezina-Cantú, Elvira Garza-González, Paola Bocanegra-Ibarias, Soraya Mendoza-Olazarán, Rayo Morfín-Otero, Adrián Camacho-Ortiz, Licet Villarreal-Treviño, Eduardo Rodríguez-Noriega, Laura Paláu-Davila, Héctor Jesús Maldonado-Garza, Samantha Flores-Treviño

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23 Citations (Scopus)


PURPOSE: Stenotrophomonas maltophilia is a multidrug-resistant opportunistic pathogen causing an increasing number of nosocomial infections. Our aim was to evaluate the risk factors and mechanisms associated with trimethoprim-sulfamethoxazole (SXT) resistance in S. maltophilia infections in Mexico.

METHODOLOGY: Clinical isolates and patients' demographic and clinical data were collected from February 2007 to August 2015 in two tertiary-care hospitals in Mexico. Antimicrobial susceptibility and analysis of sul and SmeABC and SmeDEF efflux pump overexpression were performed in all isolates.Results/Key findings. In the 9-year period, 196 patients infected with S. maltophilia were identified. Most patients were male, and the mean age was 46.2 years. The mean Charlson score was 1.42, and the most frequent comorbidities were arterial hypertension (26.7 %), type 2 diabetes (21.2 %) and cerebral infarction (11.6 %). High drug resistance to meropenem (93.4 %), gentamicin (55.1 %), ceftazidime (52.3 %), cefotaxime (51.5 %), amikacin (42.3 %) and cefepime (32.1 %), and lower resistance to ciprofloxacin (26.0 %), SXT (25.0 %), chloramphenicol (14.3 %) and levofloxacin (2.6 %) were detected. SXT resistance was not associated with the sul genes. SmeABC overexpression was associated with gentamicin (P=0.001) and levofloxacin resistance (P=0.041), whereas SmeDEF overexpression was associated with ceftazidime resistance (P=0.003). Prolonged hospitalization (≥15 days) was an independent risk factor for SXT-resistant S. maltophilia infections (OR=3.05; 95 % CI=1.12-8.86; P=0.029).

CONCLUSION: Given the high SXT resistance rate, SXT is not an effective first-line therapy for our patients; instead, levofloxacin could be used as an appropriate therapeutic option against S. maltophilia infections.

Original languageEnglish
Pages (from-to)1102-1109
Number of pages8
JournalJournal of Medical Microbiology
Issue number8
Publication statusPublished - Aug 2017
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2017 The Authors.

Copyright 2017 Elsevier B.V., All rights reserved.

All Science Journal Classification (ASJC) codes

  • Microbiology
  • Microbiology (medical)


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