The survival of Acinetobacter calcoaceticus inoculated on fingertips and on formica

Abstract

When inoculated on the fingers of three volunteers, strains of Acinetobacter calcoaceticus var. anitratus survived better than strains of var. lwoffii; 60 min after an inoculum of 10(4) cfu/finger, washings yielded between 2.6 x 10(1) (for a sporadic strain of var. lwoffii) and 7.2 x 10(2) cfu/finger (for an epidemic strain of var. anitratus). All five test strains survived better on formica than on skin, and from an inoculum of 10(4) cfu, between 6.4 x 10(2) and 2.2 x 10(3) cfu/finger were recoverable 60 min later. After inoculation of formica sheets, both strains of var. lwoffii could still be recovered in low numbers 24 h later, and two of the three strains of var. anitratus 60 h later. These findings suggest the presence of hitherto unrecognized antibacterial activity of skin against Acinetobacter calcoaceticus and suggest that outbreaks may be sustained by hand transmission. The ability of these organisms to survive desiccation on formica supports the proposal that transmission by air, dust or fomites may hitherto have been underestimated for this species.