USE OF DIFFERENT PCR-BASED DNA-FINGERPRINTING TECHNIQUES AND PULSED-FIELD GEL-ELECTROPHORESIS TO INVESTIGATE THE EPIDEMIOLOGY OF ACINETOBACTER-CALCOACETICUS ACINETOBACTER-BAUMANNII COMPLEX

Acinetobacter calcoaceticus-Acinetobacter baumannii complex is an impo rtant nosocomial pathogen for which optimal typing methods in epidemio logic investigations have not been defined. We compared DNA macrorestr iction analysis by pulsed-field gel electrophoresis (PFGE) with differ ent PCR-based DNA fingerprinting techniques, including enterobacterial repetitive intergenic consensus (ERIC) polymerase chain reaction (PCR ), repetitive extragenic palindromic (AEP) PCR, arbitrary-primed PCR w ith primer M13, and multiplex PCA with primers REP-I, REP-2 and M13, f or characterization of 98 clinical isolates (including 10 apparent out break-related isolates and 68 presumed epidemiologically unrelated iso lates) in a tertiary-care hospital over a 4-year period. The PFGE patt erns after SmaI restriction of the bacterial DNA were analyzed by comp uter software (Gelcompar) using the unweighted pair group method with arithmetic averages clustering and the Dice coefficient. A cluster of 48 isolates (cluster A), including 9 outbreak isolates, linked at a le vel of 83.4% similarity was observed. This epidemic strain and its var iants were also found among the 68 presumed epidemiologically unrelate d isolates, and this may represent ongoing endemic infection in this i nstitution. The discrimination index for the PCR-based DNA fingerprint ing techniques was 0.75 for enterobacterial repetitive intergenic cons ensus 1, 0.71 for M13, 0.77 for REP-I, 0.77 for REP-2, and 0.87 for mu ltiplex PCR. The discriminatory power of PFGE was found to be higher t han those of PCR-based techniques. It was concluded that both PFGE and PCR-based fingerprinting are useful for typing of A. calcoaceticus-A. baumannii complex. However, PFGE can detect minor mutations among out break strains, and this is important for epidemiological study of this species in a complex endemic setting. (C) 1997 Elsevier Science Inc.