By Anthony J. Brown, MD
CHICAGO (Reuters Health) – Restricting the empiric use of 3rd generation cephalosporins for mixed infections and using piperacillin/tazobactam (P/T) instead may help control the emergence of vancomycin-resistant enterococcus (VRE), according to study findings presented here on Monday at a major infectious disease meeting.
From 1995 to 1997, Dr. Debra A. Goff, and colleagues from Ohio State University Medical Center in Columbus, noticed that the VRE infection rate at their hospital tripled. In fact, this dramatic increase occurred even though the US Centers for Disease Control and Prevention treatment guidelines were followed.
In an effort to control the VRE infection rate, all 3rd generation cephalosporins were removed from the formulary as general use drugs in November 1997, the researchers state. P/T became the recommended empiric treatment for mixed infections.
After the formulary change, the number of new patients diagnosed with VRE stabilized from 1998 to 2000, Dr. Goff told attendants at the 41st Annual Interscience Conference on Antimicrobial Agents and Chemotherapy. As expected, use of 3rd generation cephalosporins and vancomycin decreased during the 3-year period.
Most gram-negative pathogens showed good susceptibility to P/T throughout the study period. Despite a large increase in P/T use, Pseudomonas aeruginosa, the most frequent nosocomial gram-negative pathogen, demonstrated good sensitivity toward P/T.
However, during the study period, a significant decrease in the percentage of Klebsiella pneumonia isolates that were sensitive to P/T occurred, the investigators note.
"Educational efforts and vancomycin control were getting us nowhere in 1997," Dr. Goff said in an interview with Reuters Health. "There were some reports, at the time, that suggested 3rd generation cephalosporin use might lead to VRE," she added. "So we decided to manipulate our formulary to see if it would have an impact."
Dr. Goff noted that "the VRE rate plateaued after the formulary change was made." Therefore, "the change appeared to have a significant impact on a pathogen with high mortality," she added.
"With all antibiotic changes you can resolve one problem but possibly create others," Dr. Goff said. "In our medical intensive care unit, we did see a decline in K. pneumonia's susceptibility to P/T," she noted. "It's a matter of priorities. At the time, we probably would have accepted an increase in K. pneumonia resistance in order to control VRE," she said.
"Other hospitals have tried similar strategies," Dr. Goff pointed out. "The strength of our study is that we followed the effect on all pathogens for 3 years after the change was made," she added. "A lot of people will look at their data after only 1 year and prematurely conclude that they have solved the problem."