Infections Caused by Imipenem-Resistant Acinetobacter calcoaceticus Biotype anitratus

• Published in: The Journal of infectious diseases Vol. 168; no. 6; pp. 1602 - 1603
• Main Authors: Wood, Craig A., Reboli, Annette C.
• Format: Journal Article
• Language: English
• Published: United States The University of Chicago Press 01.12.1993; University of Chicago Press
• Subjects: Acinetobacter; Acinetobacter calcoaceticus; Acinetobacter calcoaceticus - drug effects; Acinetobacter Infections - drug therapy; Acinetobacter Infections - epidemiology; Acinetobacter Infections - microbiology; Adult; Aged; Antibiotics; Antimicrobials; Bacteremia; Correspondence; Cross Infection - drug therapy; Cross Infection - epidemiology; Cross Infection - microbiology; Disease Outbreaks; Drug Resistance, Microbial; Humans; Imipenem - pharmacology; Infections; Infectious diseases; Male; Polymyxins
• ISSN: 0022-1899; 1537-6613
• DOI: 10.1093/infdis/168.6.1602

Our hospital recently experienced an outbreak of nosocomial infections caused by A. calcoaceticus anitratus that peaked in 1990. In that year, Acinetobacter was the third most frequently isolated genus, causing 12.9% of the nosocomial lower respiratory tract infections in our adult intensive care units. Acinetobacter organisms also caused 17 nosocomial bacteremias in that setting. Although generally resistant to all other broad-spectrum beta -lactam antibiotics, the Acinetobacter isolates were universally susceptible to imipenem until 1990, at which time we recovered imipenem-resistant isolates from 5 patients. Isolates were identified and initial susceptibility determined by using the Vitek system (BioMerieux, Hazelwood, MO). Resistance to imipenem was confirmed by broth dilution using National Committee for Clinical Laboratory Standards methodology. Broth dilution MICs were all 8-16 mu g/mL. Three of the 5 patients identified with imipenem-resistant Acinetobacter organisms were colonized only and did not require specific treatment. Two patients required treatment for infection. A 36-year-old man underwent allogeneic bone marrow transplantation for myelofibrosis and suffered respiratory failure due to recurrent pulmonary hemorrhage. The patient clinically improved with eradication of the Acinetobacter organisms after 7 days of therapy but died of Xanthomonas maltophilia bacteremia and sepsis. A 69-year-old man in respiratory failure after repair of an abdominal aortic aneurysm developed pneumonia caused by an imipenem-resistant Acinetobacter species that also was resistant to all other antibiotics routinely tested. He was treated with colistimethate, to which the isolate was susceptible by disk diffusion testing, and was cured of his infection. He died in the hospital 2 months later of cardiac arrest. There have been no additional isolates of imipenem-resistant A. calcoaceticus anitratus in our hospital since 1990.