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A pseudo-outbreak of purified protein derivative skin-test conversions caused by inappropriate testing materials
J C Grabau1, D J Burrows, M L Kern
1Bureau of Tuberculosis Control, New York State Department of Health, Albany 12237-0669, USA.
Objective:
To investigate a cluster of newly identified tuberculosis infections.
Design:
A field study was conducted including interviews; medical record reviews; checking of bills and invoices, pharmacy records, 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).
Results:
Staff had been tested with 250 TU of PPD, and 9 of 20 were tuberculin 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 tests always should check the vials to ensure that the appropriate strength solution is being used.