Researchers have used whole genome sequencing (WGS) to show the transmission of a single bacterial strain that possessed a carbapenem-resistance gene in a northern California hospital in the US. The gene armed the bacteria with resistance to carbapenems, a type of antimicrobial drug reserved as a last resort treatment for serious infections. Findings were presented on Sunday, 23 June at ASM Microbe, the annual meeting of the American Society for Microbiology.

Epidemiologists from the local public health department and the California Department of Public Health (CDPH) collaborated with laboratory scientists from the CDPH Microbial Diseases Laboratory (MDL) to characterise the strain and identify potential transmission pathways in combination with epidemiologic information.

“Our investigation highlights the importance of regular epidemiological and microbiological monitoring of resistant strains in hospitals and the use of the advanced molecular technologies to track their spread,” said Varvara Kozyreva, genotyping unit chief, Microbial Diseases Laboratory Programme at the California Department of Public Health.

Between 2013 and 2015, the hospital identified eight patients who were positive for a strain of Klebsiella pneumoniae bacteria that produced an enzyme conferring resistance to carbapenems. WGS analyses of the bacteria from these individuals demonstrated they were all highly related genetically.

“WGS allowed us to understand and demonstrate connections among the patients over a multiple year time period, which would not have been possible using epidemiologic information alone,” said Kozyreva. “Using WGS to track resistant bacterial strains can help hospitals and public health officials target infection control interventions to halt transmission sooner.”