CDC scientists from the National Antimicrobial-Resistance Monitoring System for Enteric Pathogens (NARMS) discovered a new antibiotic-resistant gene during a 2017 Salmonella Heidelberg outbreak investigation.
The outbreak strain had concerning multiple antibiotic resistance and unexplained resistance to trimethoprim/sulfamethoxazole, which is a synthetic antibiotic combination recommended for the treatment of complicated non-typhoidal Salmonella infections in humans. Resistance to this drug combination is usually due to bacteria acquiring known resistance genes.
Predicting antibiotic resistance from whole genome sequencing (WGS) analysis is an important tool during outbreak investigations and routine surveillance, due to its speed and availability. However, this report highlights the continued need for traditional antimicrobial susceptibility testing (AST). Comparison of WGS analysis and traditional AST allows NARMS to identify novel resistance genes, thereby improving the ability to predict resistance. Characterization of this novel gene was recently reported in the Journal of Antimicrobial Chemotherapy.
Sources: CDC