Methicillin resistant Staphylococcus aureus and Acinetobacter baumannii: An unexpected difference in epidemiologic behavior

Background: The Dutch guideline on hospital policy for the prevention of no socomial spread of methicillin-resistant Staphylococcus aureus (MRSA) stale s that patients transferred from hospitals abroad must be placed in strict isolation immediately on admission to a hospital in the Netherlands. Three patients colonized with both MRSA and a multiresistant Acinetobacter were t ransferred from hospitals in Mediterranean countries to 3 different hospita ls in the Netherlands. Despite isolation precautions, Acinetobacter spread in 2 of the 3 hospitals, whereas nosocomial spread of MRSA did not occur. Methods: For outbreak analysis, the Acinetobacter isolates, identified as A cinetobacter baumannii by the use of amplified ribosomal DNA restriction an alysis, were comparatively typed by 4 methods. Comparison of isolation meas ures in the hospitals was performed retrospectively. Results: In the 2 hospitals in which nosocomial spread of Acinetobacter occ urred, most of the epidemiologically related isolates were indistinguishabl e from the index strains. In these 2 hospitals, isolation measures were in concordance with those recommended for the prevention of contact transmissi on. The precautions of the hospital in which no outbreak occurred included the prevention of airborne transmission. Conclusions: Precautions recommended for multiresistant gram-negative organ isms are insufficient for the prevention of nosocomial spread of multiresis tant Acinetobacter. The airborne mode of spread of acinetobacters should be taken into account, and guidelines should be revised accordingly.