A pseudo-outbreak of Pseudomonas on a special care baby unit

Following isolation of a multi-antibiotic-resistant pseudomonad from a newborn infant on admission to the Special Care Baby Unit and further isolation of apparently the same organism from two additional infants, a full investigation was instigated in an attempt to discover the source of the organism. This revealed a further 13 infants apparently colonized with the same organism. Repeated screening of the infants with a commercial sterile swab/transport medium failed to isolate the organism. Examination of bottles of the in-house transport medium, which had been stored under a sink, produced further isolates of the same organism. Water splashed from the sink was suspected as the ultimate source of contamination. Biochemical characterization showed that P. pickettii and at least one other Pseudomonas species were involved. The epidemiological, clinical and economic implications of the 'outbreak' are discussed together with the ultimate financial implications for investigation of such incidents.