ABSTRACT
BACKGROUND: Parenteral polymyxin use declined after the 1960s, due to safety concerns. An increase in multidrug-resistant (MDR) gram-negative infections and a shortage of new agents have prompted increased use of parenteral polymyxin. OBJECTIVE: To describe our clinical experience with parenteral polymyxin B for MDR gram-negative bacteremia and urinary tract infection (UTI). METHODS: Paper pharmacy records were used to identify patients aged 18 years or older, presence of MDR gram-negative bacteremia or UTI, and use of parenteral polymyxin B for at least 48 hours. Electronic and paper patient records were then retrospectively reviewed. Polymyxin B susceptibility was evaluated using the Kirby-Bauer method. MDR isolates were defined as resistant to at least 3 antimicrobial classes, excluding polymyxin B. Microbiologic clearance was defined by 1 repeat urine or 2 repeat blood cultures that were sterile or growing different organisms. Secondary outcomes included hospital mortality and nephrotoxicity, defined as an increase in serum creatinine of 0.5 mg/dL or more, or a 50% reduction in creatinine clearance. RESULTS: Seventeen infections in 16 patients were treated with polymyxin B (1 pt. had 2 infections that were analyzed separately). Microbiologic clearance occurred in 14 of 16 (88%) cases of MDR gram-negative bacteremia or UTI in which repeat cultures were done. Ten of 16 patients died (all-cause mortality 63%). Five patients required hemodialysis prior to polymyxin B use. Six (55%) of the remaining 11 patients with baseline renal insufficiency developed nephrotoxicity, and none of them required hemodialysis. The mean +/- SD number of days from the initiation of therapy to the onset of nephrotoxicity was 7.5 +/- 2.3 (range 4-10) days. Three (50%) of 6 patients with nephrotoxicity died. CONCLUSIONS: Our data suggest that polymyxin B may be effective for MDR gram-negative infections in patients with limited therapeutic options, but precautions should be taken to avoid toxicity.
Subject(s)
Bacteremia/drug therapy , Drug Resistance, Multiple, Bacterial , Gram-Negative Bacterial Infections/drug therapy , Polymyxin B/administration & dosage , Polymyxin B/therapeutic use , Urinary Tract Infections/drug therapy , Adult , Aged , Aged, 80 and over , Anti-Bacterial Agents/administration & dosage , Anti-Bacterial Agents/adverse effects , Anti-Bacterial Agents/therapeutic use , Bacteremia/microbiology , Gram-Negative Bacteria/drug effects , Humans , Male , Microbial Sensitivity Tests , Middle Aged , Polymyxin B/adverse effects , Retrospective Studies , Urinary Tract Infections/microbiologyABSTRACT
Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has rarely been reported in the hospital setting. We report an outbreak of 7 cases of skin and soft tissue infections due to a strain of CA-MRSA. All patients were admitted to the labor and delivery, nursery, or maternity units during a 3-week period. Genetic fingerprinting showed that the outbreak strain was closely related to the USA 400 strain that includes the midwestern strain MW2. All isolates contained the staphylococcal chromosome cassette mec type IV. Genes for Panton-Valentine leukocidin and staphylococcal enterotoxin K were detected in all isolates, and most contained other enterotoxin genes. Testing of nearly 2,000 MRSA isolates collected during citywide surveillance studies from 1999 to 2003 showed that approximate, equals 1% were genetically related to MW2. CA-MRSA strain MW2 has been present in this region at least since 1999. This study documents the spread of this strain among healthy newborns at 1 hospital.
