A PSEUDO-OUTBREAK OF PURIFIED PROTEIN DERIVATIVE SKIN-TEST CONVERSIONS CAUSED BY INAPPROPRIATE TESTING MATERIALS

OBJECTIVE: To investigate a cluster of newly identified tuberculosis i nfections. DESIGN: A field study was conducted including interviews; m edical record reviews; checking of bills and invoices, pharmacy record s, and drug manufacturer information; and clinical retesting. SETTING: Community residential facilities providing comprehensive services to retarded adults. PARTICIPANTS: Twenty residential facility staff (not previously known to be purified protein derivative [PPD] positive). RE SULTS: Staff had been tested with 250 TU of PPD, and 9 of 20 were tube rculin positive. Retesting with 5 TU yielded no reaction. CONCLUSIONS: Reactions were attributable to testing with a product not recommended for routine PPD screening. Healthcare workers planting PPD Mantoux te sts always should check the vials to ensure that the appropriate stren gth solution is being used (Infect Control Hosp Epidemiol 1997;18:571- 574).