Nosocomial pseudoepidemic caused by Bacillus cereus traced to contaminatedethyl alcohol from a liquor factory

From September 1990 to October 1990, 15 patients who were admitted to four different departments of the National Taiwan University Hospital, including nine patients in the emergency department, three in the hematology/oncolog y ward, two in the surgical intensive care unit, and one in a pediatric war d, were found to have positive blood (14 patients) or pleural effusion (1 p atient) cultures for Bacillus cereus. After extensive surveillance cultures , 19 additional isolates of B. cereus were recovered from 70% ethyl alcohol that had been used as a skin disinfectant (14 isolates from different loca tions in the hospital) and from 95% ethyl alcohol (5 isolates from five alc ohol tanks in the pharmacy department), and 10 isolates were recovered from 95% ethyl alcohol from the factory which supplied the alcohol to the hospi tal. In addition to these 44 isolates of B. cereus, 12 epidemiologically un related B. cereus isolates, one Bacillus sphaericus isolate from a blood sp ecimen from a patient seen in May 1990, and two B. sphaericus isolates from 95% alcohol in the liquor factory were also studied for their microbiologi cal relatedness. Among these isolates, antibiotypes were determined by usin g the disk diffusion method and the E test, biotypes were created with the results of the Vitek Bacillus Biochemical Card test, and random amplified p olymorphic DNA (RAPD) patterns were generated by arbitrarily primed PCR Two clones of the 15 B. cereus isolates recovered from patients were identifie d (clone A from 2 patients and clone B from 13 patients), and all 29 isolat es of B. cereus recovered from 70 or 95% ethyl alcohol in the hospital or i n the factory. belonged to clone B. The antibiotype and RAPD pattern of the B. sphaericus isolate from the patient were different from those of isolat es from the factory. Our data show that the pseudoepidemic was caused by a clone (clone B) of B. cereus from contaminated 70% ethyl alcohol used in th e hospital, which we successfully traced to preexisting contaminated 95% et hyl alcohol from the supplier, and by another clone (clone A) without an id entifiable source.