Poster (Painel)
533-2Characterization of antimicrobial susceptibility of Listeria spp. strains isolated from environment, food and human infection
Autores:Luisa Zanolli Moreno (FSP - USP - Faculdade de Saúde Pública - USP / FMVZ - USP - Faculdade de Medicina Veterinária e Zootecnia - USP) ; Andrea Micke Moreno (FMVZ - USP - Faculdade de Medicina Veterinária e Zootecnia - USP) ; Glavur Rogério Matté (FSP - USP - Faculdade de Saúde Pública - USP) ; Maria Helena Matté (FSP - USP - Faculdade de Saúde Pública - USP)


Introduction: Listeria is a Gram-positive pathogen of public health concern. Although it is considered widely susceptible to clinically relevant classes of antibiotics, recent studies have reported an increased rate of resistance on pathogenic L. monocytogenes. The emergence of resistance is not exclusively for L. monocytogenes but also for other Listeria species that may represent reservoirs of antimicrobial resistance. Objective: Characterize antimicrobial resistance profile of Listeria spp. isolates originated from human infection, environment and food. Material and Methods: A total of 46 strains were studied, of which 24 were serotyped as L. monocytogenes, 12 L. innocua, two L. seeligeri, two L. welshimeri and two L. ivanovii. The resistance profile was determined by broth microdilution method using antimicrobials plaques for Gram- positive and negative bacteria (GPALL1F and ESB1F) (Sensititre®/Thermo Fisher Scientific) and the minimal inhibitory concentrations were analyzed using the Clinical and Laboratory Standard Institute criteria for S. aureus ATCC 29213. Results and Discussion: All Listeria spp. strains were resistant to at least one of the tested antimicrobials. From the 46 isolates, 24 (52%) were resistant to penicillin, of which 50% were L. innocua. Resistance to clindamycin, ampicillin and oxacillin was also found among L. monocytogenes and L. innocua strains, including L. monocytogenes human isolates. These results demonstrate the emergence of Listeria resistance and its risk to public health since these antimicrobials are commonly used to treat listeriosis and other Gram-positive infections. Interestingly, 37% of the isolates displayed resistance to daptomycin, a recently approved antimicrobial in Latin America, specific to Gram-positive infections. Furthermore, all Listeria species studied presented at least intermediary resistance to ciprofloxacin, levofloxacin and moxifloxacin. In contrast to the European and American scenario, all isolates were sensible to tetracycline, erythromycin, rifampicin and trimethoprim–sulfamethoxazole. Conclusions: These results confirm the emergence of resistance in Listeria genus to antimicrobials that are used to Gram- positive and negative infections. This resistance may compromises listeriosis treatment and also indicates that Listeria may be a reservoir of antimicrobial resistance to other bacteria.

Palavras-chave:   Antimicrobial resistence, Human infection, Listeria spp., Listeria monocytogenes