Sarah Goodwin

Kathi Ovnic
Holly Korschun
November 16, 1998


DENVER--Researchers from Emory University's Rollins School of Public Health and the U.S. Centers for Disease Control and Prevention (CDC) have demonstrated that hospital tests of antibiotic resistance to an important drug ­ imipinem ­ against two common causes of hospital infections two common hospital infections ­ Enterobacteriaceae and Pseudomonas aeruginosa ­ are often inaccurate. John McGowan, M.D., professor of epidemiology at Emory's Rollins School of Public Health presented the study results at the Annual Meeting of the Infectious Diseases Society of America Nov. 14 in Denver.

In a study that included 34 hospitals across the United States, the investigators re-tested isolates of the two bacteria that had previously been determined by the hospital laboratories to be either moderately resistant (intermediate) or resistant to the antibiotic imipenem.

Out of 84 isolates of Enterobacteriaceae labeled by the hospitals as imipenem intermediate (I) or resistant (R), only 8 (9.5%) were found by the Emory and CDC investigators to be imipenem I or R. Out of 223 isolates of P. aeruginosa submitted by the hospitals as I or R, only 165 (74%) were confirmed as imipenem I or R.

The research was conducted through Project ICARE, a joint study between Emory University's Rollins School of Public Health and the CDC to collect, analyze and rapidly report information about national patterns of antibiotic use and resistance in hospital intensive care units. In addition to Dr. McGowan, the ICARE study is headed by co-principal investigators Robert Gaynes, M.D., director of CDC's National Nosocomial Infections Surveillance System and adjunct associate professor at Emory and Fred Tenover, Ph.D., head of CDC's Nosocomial Pathology Laboratory Branch and adjunct associate professor at Emory.

One goal of the study is to develop and improve mechanisms for surveillance, reporting and analysis of data on antibiotic resistance. The results can then be used to offer advice to hospitals and generate data to spark future research.

The study of imipenem resistance suggests that previous concerns about imipenem testing are still warranted, Dr. McGowan says. The problems with testing may arise because imipenem degrades easily and testing must be monitored carefully. Several different test methods may be needed to verify resistance to imipenem.

Validating data about antibiotic resistance before using the data to make decisions is critical, emphasizes Dr. McGowan. "This study points out a potential clinical problem, since imipenem could be needlessly subtracted from a list of usable antimicrobial agents."

The research was funded by the Centers for Disease Control and Prevention.

For more general information on The Robert W. Woodruff Health Sciences Center, call Health Sciences Communication's Office at 404-727-5686, or send e-mail to

Copyright ©Emory University, 1998. All Rights Reserved.