Staph Sleuth Detects, Dissects and Protects

Francoise Perdreau-
Remington

Editor's Note:
Since publication of this story on February 10, 2006, Francoise Perdreau-Remington and her team have announced their decoding of the CA-MRSA genome. The paper appears in the February 25 issue of Lancet. Readers must register.
Medical mysteries demand detectives, and in Francoise Perdreau-Remington, San Francisco General Hospital (SFGH) has a bacteria sleuth of the first order. As director of the Molecular Epidemiology Research Laboratory, a lab she founded at SFGH in 1995 with a grant from Pfizer and in collaboration with Julie Gerberding, current director of the Centers for Disease Control (CDC), Perdreau-Remington and her team - including a changing cast of students from UC Berkeley - were the first to identify a virulent, drug-resistant form of staph known as community-associated methicillin-resistant Staphylococcus aureus, or CA-MRSA. Her team also seems likely to be the first to sequence the genome of this bacterium, a project being spearheaded by newly minted PhD Binh An Diep, who recently completed his doctoral degree under the mentorship of Perdreau- Remington and George Sensabaugh of UC Berkeley. The sequencing would be the first step to understanding - and perhaps containing - an infection that, once out of control, can develop rapidly from red bumps and boils to deadly lung or blood infections. In her role as "chief of bacterial intelligence" for the infection control division at SFGH, Perdreau-Remington gathers data on the spread and prevalence of CA-MRSA in the wards and, by inference, throughout the city. "The route of this epidemic has been unusual. It came from the community and spread into the hospital, not the other way around," says the French-born microbiologist.
Proof comes in the lab's 10,000 samples dating back to 1996. The samples come from throughout San Francisco's Community Health Network, which includes not only SFGH, but neighborhood clinics, Laguna Honda Hospital and the city jail. The decade-long stream of data shows the speed at which the staph variant, dubbed USA300 by the CDC, has conquered and replaced its less dangerous staph cousins. In 1996, of the 800 individuals from the Community Health Network with known staph infections, 145 had MRSA. In 2004, of the 1,800 staph infections detected, 1,240 had MRSA. Across the US, the totals are in the tens of thousands, experts estimate. For most patients, the infection is treatable. The problem, Perdreau-Remington explains, is differential diagnosis. "Many patients have no prior risk factors. The doctors do not suspect a resistant strain, so they treat it like a regular infection." The lack of vigilance may now be changing, thanks to an awareness campaign launched by the CDC. Fueling the urgency are public health estimates that more than 2 million Americans already harbor the drug-resistant strain without symptoms. The bacteria live harmlessly in the nose. "Just think how many times you touch your nose over the course of a day," Perdreau-Remington says. Perhaps with increased national attention to the CA-MRSA problem, Perdreau-Remington will be spared her annual scramble for grants to augment the 20 percent of her budget that comes from SFGH's infection control contract with the city. In the meantime, it is a scramble she gladly makes. "You need molecular techniques to understand how an infection spreads and how resistance develops. And you need to do cultures to know what you're dealing with. Otherwise, while you might be able to treat a patient successfully, you can't help prevent reinfection." Of course, Perdreau-Remington would also be pleased if her research helped speed the creation of a new killer drug that could contain CA-MRSA. Short of that, she offers this bit of motherly advice: "Wash your hands." Photo by Elisabeth Fall Source: Jeff Miller