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"Old" Antibiotic Polymyxin B Effective in Treating Drug-Resistant Gram-Negative Infections: Presented at ICAAC

By Ed Susman

CHICAGO, IL -- September 16, 2003 -- Patients with drug-resistant Gram-negative bacterial infections have been treated successfully with a "forgotten" antibiotic, polymyxin B, researchers noted here September 15^th at the 43^rd Annual Interscience Conference on Antimicrobial Agents and Chemotherapy.

"The emergence of multi-drug-resistant infections in the hospital setting is a growing problem worldwide," said lead researcher Andrea L. Kwa, BSc, Department of Pharmacy Services, Singapore General Hospital.

Dr. Kwa and colleagues enrolled 26 patients with multi-drug resistant infections caused by Acinetobacter baumannii and Pseudomonas aeruginosa and treated them with intravenous doses of polymyxin B in doses ranging from 250,000 units to 750,000 units twice a day.

"Microbiological cure was seen in 53.8% of patients and clinical improvement was seen in 96.2% of cases," said Ms. Kwa. "The kidney function before and after polymyxin B therapy did not differ significantly, suggesting that kidney toxicity attributed to this old antibiotic warrants re-evaluation. One patient had lower-limb weakness associated with polymyxin B, which resolved upon drug discontinuation."

Fifteen of the 26 patients were major burn victims; 18 had acinetobacter infections; 8 had pseudomonas infections.

Patients who had documented systemic Gram-negative infections and were prescribed polymyxin B were identified through the hospital's pharmacy database. The patients were treated between Jan. 1, 2000 and Jan. 1, 2003. The medical records were reviewed, and pertinent information was recorded retrospectively.

Ms. Kwa said that polymyxin B was used extensively in the 1960s through the 1980s, but its use was abandoned because it was found to give rise to toxicities in the kidneys, nerves and brain. Physicians have been increasingly interested in the use of polymyxin B as drug resistance among common pathogens grows.

"There are some hospitals in the United States and abroad where the only effective drug left in their antibiotic arsenal is polymyxin B," said Ronald Jones, MD, The Jones Group, North Liberty, Iowa. Dr. Jones, an expert in antibiotic-drug resistance, said he and his associates are dismayed by the lack of antibiotics in development to confront the Gram-negative organisms, especially acinetobacter and pseudomonas species.

Ms. Kwa concluded, "Our preliminary data suggest that polymyxin B is reasonably efficacious and safe in the treatment of multi-drug-resistant infections in the hospital setting." She suggested that the role of polymyxin B in infectious diseases deserves further investigation.


[Study title: Polymyxin B (PB) in the Treatment of Multidrug Resistant (MDR) Gram-Negative (GN) Infections. Abstract K-701]

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