Pseudobacteraemia with multiply-resistant Klebsiella pneumoniae resulting from contamination from the blood gas machine on a neonatal unit.

Klebsiella pneumoniae with an unusual antibiotic susceptibility pattern was isolated from blood cultures of seven unwell premature babies on the Special Care Baby Unit. Although the organism was sensitive to cefuroxime it was resistant to ceftazidime. It was also resistant to gentamicin, tobramycin, netilmicin, piperacillin and aztreonam but sensitive to ciprofloxacin, imipenem and amikacin. On extensive investigation to trace the source, a K. pneumoniae with the same susceptibility pattern as that obtained from blood cultures was isolated from the probe and probe cover on the blood gas machine but not from any other environmental samples or clinical specimens. Where clinically indicated, antibiotics were used to treat these babies, with success. The difficulty, however, of differentiating between true septicaemia and pseudobacteraemia could be enormous as withholding treatment will have disastrous consequences in genuine cases of bacteraemia.