Julia Arantes Galvão

Chicken Meat as a Reservoir of Colistin-Resistant Escherichia coli Strains Carrying mcr-1 Genes in South America

ABSTRACT The detection and rapid spread of colistin-resistant Enterobacteriaceae carrying the mcr-1 gene has created an urgent need to strengthen surveillance. In this study, eight clonally unrelated colistin-resistant Escherichia coli isolates carrying mcr-1 and blaCTX-M or blaCMY-2 genes were isolated from commercial chicken meat in Brazil. Most E. coli strains carried IncX4 plasmids, previously identified in human and animal isolates. These results highlight a new reservoir of mcr-1-harboring E. coli strains in South America.

Multiscreening LC-MS/MS Designed for Ten Pesticide and Six Antimicrobial Residues in Eggs

A multiscreening method was experimentally validated for pesticide and antimicrobial residues in spiked eggs at levels of 5, 50, and 500 μg L−1. The residue extraction was performed with acetonitrile and 1% formic acid. The extracted material was stored at −70°C until detection and quantitation within 24-hour period by LC-MS/MS. Pesticide and antimicrobial residue recovery performed adequate standard deviation and the results were from 94.10% (ampa) to 9.20% (carbaryl) for pesticides and from 95.70% (enrofloxacin) to 46.20% (sulfathiazole) for antimicrobial. The method was highly accurate, considering the linearity for all pesticide and antimicrobial residues (), with quantitation limits ranging from 0.78 to 6.25 μg L−1 for pesticides and 0.78 to 3.13 μg L−1 for antibiotics. A highly correlation coefficient () was found, except for carbaryl. Although time extraction and carbaryl recovery remain to be improved, the method has shown a rapid pesticide and antimicrobial residue detection.