Doug Conrad recalls reviewing the lab analysis of a sputum culture from an adult with cystic fibrosis whom he treated in 2010. The hallmark of cystic fibrosis is prolonged infection, especially in the lungs, so knowing the types of pathogens present in the lungs is useful for determining appropriate treatment. “She coughed up a lot of sputum everyday,” says Conrad, director of the Adult Cystic Fibrosis Clinic at the University of California, San Diego (UCSD). “But the laboratory could only come up with a diagnosis of 'normal respiratory flora.'” Conrad, however, was not convinced. “It may be respiratory flora, but it's not normal,” he remembers thinking.
In diseases such as cystic fibrosis, the movement of certain microbes to certain lung regions can determine the extent of disease and be responsible for flare-ups. Understanding the location and types of bacteria in the lungs could lead to drastically more-effective treatments for potentially fatal lung infections in people with cystic fibrosis. Yet detailed knowledge about the microbes in the lungs has been lacking. In the case of Conrad's patient, without precise information from the sputum culture, he could place the woman only on various wide-spectrum antibiotics, from topomycin to doxycycline. Finally, by trial and error, he gave the patient linezolid, an antibiotic that improved her symptoms.
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