Pseudobacteremia: false-positive blood cultures from mist tent contamination

In the seven-month period from July 1975 through January 1976, 11 pediatric patients had Acinetobacter calcoaceticus var. anitratus cultured from blood; this organism had not been isolated from pediatric patients in the previous six months. In 10 of 11 patients, only the first of two cultures was positive. All patients recovered uneventfully, although only two were treated with appropriate antibiotics. Nine of 11 had been in mist tents at the time of the culture. Mist cultured from one tent contained the same organism found in the patient's blood culture. Eight of 10 patients, however, had blood for culture drawn from the same needle as samples for other blood work, compared with only three of 13 controls (p = .013); this represented a deviation from proper blood culture technique, and a mock trial confirmed contamination of blood cultures when technique was broken. Contamination by this organism occurred in the tent water reservoir and mist, and the nose and skin of the children were colonized. The hands of respiratory therapy technicians and blood-drawing personnel became contaminated while handling the mist tents. Thorough attention to hand-washing, tent sterilization, and technique in drawing blood cultures stopped the pseudo-epidemic.