Exploratory study of antimicrobial resistant bacteria isolated from Psychodinae in a tertiary-level teaching hospital in Rio de Janeiro, Brazil

Abstract

Psychodinae, or 'drain flies', constitute a subfamily of insects within the Psychodidae family, commonly found in human-modified environments. Although generally considered harmless, they have been identified as potential carriers of pathogenic microorganisms. These flies may contribute to contamination in healthcare settings and could therefore be involved in healthcare-associated infections. To investigate the potential of Psychodinae as reservoirs of Gram-negative antimicrobial resistant bacteria in a hospital in the state of Rio de Janeiro, specimens were collected, processed, macerated, and used to inoculate a variety of selective bacterial media. Identification of pure cultures was performed by MALDI-TOF MS (Bruker), and antimicrobial susceptibility was assessed via the Kirby-Bauer method as well as determination of Minimum Inhibitory Concentration (MIC) for polymyxin. Extracted DNA samples were subjected to polymerase chain reaction (PCR) for genotypic detection of a range of enzymatic resistance mechanisms. A total of 115 bacterial isolates were obtained from 45 specimens of Psychodinae. The predominant genera were Acinetobacter spp. (34.5%) and Pseudomonas spp. (31%). Twenty-seven isolates were resistant to multiple drugs, and fragments of the genes bla_OXA-143, bla_NDM, bla_CTX−M, and bla_TEM were detected by PCR. These findings corroborate and expand upon data from phenotypic studies, which suggested that drain flies may harbor resistant bacteria. This study represents the first genotypic analysis of antimicrobial resistance in drain flies. Based on these results, the incorporation of drain flies into surveillance and control programs is recommended. This perspective is expected to contribute to the development of novel, effective strategies for vector management and the investigation of other possible sources of contamination in hospitals.