INFECTED IMPLANT: In vivo optical imaging of a titanium bone implant (blue) in a mouse femur combines bioluminescence, fluorescence, and CT imaging. The yellow areas show colocalization of an injected strain of bioluminescent Staphylococcus aureus (red) and fluorescently labeled neutrophils (green), early immune responders to infections. COURTESY OF LLOYD MILLER, MD, PHDEpidemiologists are sleuths who track infections—what causes them and how they spread through a geographical area over time. Another kind of infection sleuth wants to know whether or how infections spread within the living body—as in the case of medical implants that get infected, or tuberculosis that moves from the lungs to other tissues—and whether infection hot spots will succumb to immune-system attack or to drugs over time.
Used most often in mice and other small rodents, in vivo optical imaging “is one really powerful tool to noninvasively monitor infection over time,” says Lloyd Miller, an associate professor of dermatology and orthopedic surgery at Johns Hopkins School of Medicine. Using a mouse orthopedic implant model, his group simultaneously tracks the spread of Staphylococcus aureus and the responses of the animals’ immune cells, such as neutrophils.
The method is powered by new refinements in fluorescent probes and in bioluminescently labeled pathogens. And a number of instruments now allow researchers to merge light-based imaging with other imaging modalities, such as CT scans. With these tools, infectious-disease researchers can probe deeper into the bodies of small animals, examining the effects of pathogens on their hearts and ...
