Correlation of six methods for typing nosocomial isolates of Acinetobacter baumannii

A comparative study of biotyping, antimicrobial susceptibility, whole-cell protein analysis, plasmid analysis, pulsed-field gel electrophoresis of chromosomal DNA and polymerase chain reaction with arbitrary primers of Acinetobacter baumannii isolates from three large hospitals was performed to determine the best markers for epidemiological purposes. Ninety-two isolates were included: 38 belonged to a previously described outbreak and 54 were randomly selected from sporadic cases of infection. Biotyping, whole-cell protein and plasmid analysis were the least discriminatory methods, whereas antimicrobial susceptibility and polymerase chain reaction with arbitrary primers showed moderate discriminatory power. Typing based on pulsed-field gel electrophoresis of chromosomal DNA appeared to be the best discriminatory method (discrimination index of 0.9623). The addition of polymerase chain reaction with arbitrary primers or antimicrobial susceptibility to pulsed-field gel electrophoresis of chromosomal DNA did not further increase the discriminatory power.