Antibiotic Resistance of Listeria monocytogenes Isolated from Meat Processing Environments, Foods, and Clinical Cases in Brazil

Introduction: In the last years, studies showed large increase in the description of antibiotic resistant strains. The emergence of antimicrobial resistance has serious consequences for public health, which makes monitoring, an important measure to be taken.

Purpose: Assess the antimicrobial resistance of Listeria monocytogenes obtained in different sources and Brazilian regions.

Methods: A total of 137 L. monocytogenes isolates, from 11 different States of Brazil were analyzed in this study. They were identified by biochemical tests and molecular serogrouping. The presence of virulence markers genes (inlA, inlC, inlJ) was also checked. And all strains were subjected to phenotypical analysis to characterize their resistance against 12 antimicrobials.

Results: The isolates were classified into serogroups 4b, 4a, 4c, or 4d (46%), 1/2c or 3c (27%), 1/2a or 3a (13.9%), and 1/2b or 3b (13.1%). Virulence markers were detected in all isolates, and most of tested isolates presented sensitivity to the majority of antimicrobials, but presented resistance or intermediate resistance to clindamycin (88.3%) and oxacillin (73.7%).

Significance: This study showed the prevalence of pathogenic serogroups among isolates. Despite having susceptibility to most of the antibiotics used to treat Listeriosis, the presence of high antimicrobial resistance to oxacillin and clindamycin is a serious concern for public health, and more in depth research is needed to better understand the mechanisms of antimicrobial resistance. 

Acknowledgments: CNPq, CAPES, and FAPEMIG.