MUSCA DOMESTICA AS A VECTOR OF COLISTIN-RESISTANT BACTERIA FROM LANDFILLS AT TWO MARKETS IN SANTA ANITA-LIMA

Alarcón Calle M.Á.; Rodrigo Rojas M.E.; Salas Asencios R.; Yareta Yareta J.L.; Carbajal P.M. · Revista de la Facultad de Medicina Humana (2026) · DOI: 10.25176/rfmh.v26i2.8035

Resumen

Introduction: Musca domestica can carry antimicrobial-resistant bacteria. Objectives: To evaluate its role as a vector of bacteria with phenotypic and genotypic resistance to colistin associated with the mcr-1 gene. Methods: A descriptive study was conducted between February and July 2023 in two market dumpsites in Santa Anita, Lima, Peru. A total of 60 flies were collected using adhesive plates baited with chicken. Samples were enriched in Tryptic Soy Broth and cultured on MacConkey agar. Bacterial identification was performed using conventional biochemical tests and MicroScan® for non-Enterobacteriaceae bacteria. Colistin resistance was assessed using the disk elution method in cation-adjusted Mueller-Hinton broth. Bacterial DNA was extracted using a commercial kit, and the mcr-1 gene was detected by conventional PCR. Results: Seventy-four bacterial isolates belonging to eight genera and 12 species were recovered. Escherichia coli was the most frequent species, accounting for 24.3% of isolates, followed by Klebsiella oxytoca, Proteus mirabilis, Klebsiella pneumoniae, and Klebsiella aerogenes. Phenotypic resistance to colistin was identified in 79.7% of isolates, with a minimum inhibitory concentration (MIC) ≥4 μg/mL. The mcr-1 gene was detected in four isolates of Klebsiella oxytoca, Klebsiella pneumoniae, and Escherichia coli. The association between phenotypic resistance and detection of the mcr-1 gene was significant, with a p-value of 0.035. Conclusion: Musca domestica may act as a mechanical carrier of colistin-resistant bacteria in urban dumpsites; therefore, its surveillance should be integrated into antimicrobial resistance control programs. Artículo publicado por la Revista de la Facultad de Medicina Humana de la Universidad Ricardo Palma. Es un artículo de acceso abierto, distribuído bajo los términos de la Licencia Creative Commons: Creative Commons Attribution 4.0 International, CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/), que permite el uso no comercial, distribución y reproducción en cualquier medio, siempre que la obra original sea debidamente citada. Para uso comercial, por favor póngase en contacto con revista.medicina@urp.pe

Instituciones: Universidad Ricardo Palma; Universidad Nacional Federico Villarreal; Universidad Peruana Unión