Abstract
Acinetobacter baumannii has been associated with several severe hospital-acquired infections such as ventilator-associated pneumonia and meningitis. Sulbactam, a β-lactamase inhibitor, is usually combined with β-lactam antibiotics to treat infections. It has been found that sulbactam alone could be used to treat infections caused by A. baumannii. The mechanism of bacteticidal effect of sulbactam remains unknown. Proteomics was used to analyze protein intensity changes and identify the proteins of A. baumannii after sulbactam treatment. There were 54 proteins found to exhibit significant changes in intensity. The reduced proteins include adenosine triphosphate-binding cassette (ABC) transporters, and 30s, 50s ribosomal subunit proteins. These proteins are essential for nutrient import and protein syntheses and are vital for bacterial survival. The amplified proteins include glutamine synthetase, malic enzyme, RNA polymerase subunit α, and molecular chaperone DnaK and GroEL. They function in metabolism, DNA and protein syntheses, and repair machinery. These amplified proteins were increased for rescuing bacteria. However, their increases could not overcome the effects of the reduced proteins and the bacteria killed. This is the first report that the reduction of ABC transporters and the 30s, 50s ribosomal subunit proteins plays an important role for the bactericidal effect of sulbactam against A. baumannii.