Variation in skin and environmental survival of hospital gentamicin-resistant enterobacteria

During a period when 245 patients were infected by or harboured gentamicin-resistant enterobacteria, random sampling showed hand carriage in 33% of affected patients but in only 5% of attendant staff. Only klebsiellae were isolated from the latter. Recovery was commoner from the hands of bed-ridden patients or faecal carriers and significantly more frequent for klebsiellae (37%) and enterobacter (33%) than citrobacter (5.6%) and E. coli (5.0%). Similarly, survival on forearms of volunteers was much longer for klebsiellae and enterobacter than for citrobacter or E. coli (means respectively were 70, 45, 10 and 13 min), and on dry surfaces (means respectively were 28, 26, 3 and 7 h). Klebsiellae were isolated from 17 of the 56 dry environmental surfaces sampled. The presence of plasmid resistance determinants had no effect on survival times, either on the skin or following drying onto formica surfaces. On dry surfaces 9.5% of E. coli but only 1.3% of klebsiellae lost resistance to gentamicin. These findings accord well with recent experience in which gentamicin-resistant klebsiellae have been involved to a much greater extent than other resistant enterobacteria in hospital infection.