A newly introduced, multi-drug resistant (MDR) strain of Pseudomonas aerugi
nosa was isolated from four patients admitted to the Concord Hospital Burns
Unit (BU) between December 1997 and March 1998. It was the cause of recurr
ent episodes of bacteraemia in two. This strain was resistant in vitro to g
entamicin, piperacillin and ciprofloxacin. The isolates were confirmed as a
clonal strain by pulse field gel electrophoresis (PFGE). Multiple environm
ental swabs were taken to search for an environmental reservoir, but no sou
rce was identified. Random cultures of staff members' hands failed to demon
strate ongoing carriage. In the absence of a demonstrable point source for
the outbreak, direct cross-transmission patient to patient, via transient s
taff hand contamination. was the most likely route of infection. Following
study commencement no new cases of infection with the MDR strain were detec
ted. It would appear that the infection cycle has been interrupted, and the
outbreak terminated following the discharge of the last infected patient f
rom the BU. Contamination of a neutral detergent in the BU with Klebsiella
oxytoca was detected incidentally during environmental surveillance. A pote
ntial hospital-wide outbreak was averted. (C) 2001 Elsevier Science Ltd and
ISBI. All rights reserved.