093: Biofilms and metagenomic diagnostics in clinical infections with Robin Patel

Robin Patel discusses her work on prosthetic joint infections and how metagenomics is changing infectious disease diagnostic procedures.

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Julie’s Biggest Takeaways:

The term antimicrobial resistance can mean many things. Although acquisition of genetic elements can lead to drug resistance, so can different growth lifestyles of bacteria; the same bacteria growing in liquid culture may be more susceptible to a drug than those bacteria growing on a biofilm. Lifestyle and genetics can intertwine, however, when bacteria growing as a biofilm exchange resistance genes through horizontal gene transfer.

How do bacteria reach an implanted surface, such as on a prosthetic joint, to cause infection? It may rarely occur during surgery, if even a single bacterium reaches the joint surface despite the sterile conditions; alternatively, it could occur through hematogenous spread (through the blood) after the surgery is over. Most infections are believed to be seeded at the time of implantation.

While scientists don’t perform teeny, tiny implants in animal models of infection, the materials are placed in animal bone to mimic as similar an immune response as possible.

Targeted metagenomics and shotgun metagenomics are both being developed clinically. Targeted metagenomics looks at one specific gene found in a number of species, such as the 16S ribosomal RNA gene. Shotgun metagenomic looks at all DNA present, and requires a lot more cleaning up to eliminate human genomic material, which is the major sequence of any human-derived sample.