Serratia cross-infection in an intensive therapy unit.

During a 10-week period, 11 patients were involved in an outbreak of cross-infection with a non-pigmented strain of Serratia marcescens resistant to sulphonamides, trimethoprim, ampicillin, tetracycline, chloramphenicol, cephalexin, gentamicin, tobramycin, colistin, ticarcillin and kanamycin. The problem was confined to the intensive therapy areas of the hospital. The organism was apparently spread by a nursing sister who harboured it in a paronychial lesion. Prolonged carriage of S. marcescens was demonstrated. Methods of investigation of the outbreak and the measures adopted to terminate it are described.