Clinical importance and antibiotic resistance of Acinetobacter spp.

Members of the genus Acinetobacter, particularly multiresistant strains of A, baumannii, are implicated in a wide spectrum of nosocomial infections, including bacteraemia, secondary meningitis and urinary tract infection, but have now assumed a particularly important role as agents of nosocomial pneumonia in intensive care units (ICUs), Rapid genotyping methods for the identification and typing of these organisms have allowed a better appreciation of the epidemiology and survival of these organisms in the hospital environment, Their emergence as significant pathogens seems to be related partly to their survival ability and partly to their ability to develop resistance rapidly to the major groups of antibiotics, resulting in a considerable selective advantage in environments (such as ICUs) with widespread and heavy use of antibiotics, Molecular and biochemical mechanisms of resistance to the major beta-lactam, aminoglycoside and quinolone groups of antibiotics have now been elucidated in some detail for these organisms, and experimental models, including a mouse model of A, baumannii pneumonia, have been developed to examine the efficacy of different therapeutic regimens for difficult-to-treat-infections caused by these bacteria, 'Non-classic' antibiotic combinations-such as ticarcillin with clavulanic acid and sulbactam-seem to show promise for treating systemic infections caused by otherwise multiresistant strains, but revised screening procedures in the pharmaceutical industry may be required in the near future to select novel compounds with activity against multiresistant Acinetobacter spp, and other emerging gram-negative, non-fermentative bacilli in general.