Use of macrorestriction analysis to demonstrate interhospital spread of multiresistant Acinetobacter baumannii in Sao Paulo, Brazil

We evaluated the spread of Acinetobacter baumannii strains among three hospitals located in Sao Paulo, Brazil. A total of 46 isolates, which were typed by chromosomal DNA analysis with use of pulsed field gel electrophoresis (PFGE), were tested for susceptibility to the fluoroquinolones, carbapenems, aminoglycosides (amikacin), cephalosporins, polymyxin B, and ampicillin/sulbactam by means of the broth microdilution method, disk diffusion, and the E-test. Isolates with an identical PFGE pattern (pattern B) that were susceptible only to carbapenems, polymyxin B, and ampicillin/sulbactam were recovered in all three hospitals. In addition, isolates with PFGE pattern A that were susceptible only to polymyxin B and ampicillin/sulbactam were recovered in hospitals 1 and 2. The results of our study strongly suggest the interhospital transmission of multiresistant epidemic strains of A. baumannii in Sao Paulo. Once in the hospital, these strains can disseminate and cause outbreaks with devastating consequences.