False-positive cryptococcal antigen test and cervical prevertebral abscess

S. MacKinnon, J. G. Kane and R. H. Parker

A false-positive latex agglutination test for cryptococcal antigen occurred in a patient with a cervical prevertebral abscess and vertebral osteomyelitis caused by Klebsiella pneumoniae. Using a commercial latex agglutination test kit, a cryptococcal antigen titer of 1:32 was found in the CSF, but no cryptococcal antigen was found when the CSF was retested at a reference laboratory. The false-positive test resulted in unnecessary therapy with amphotericin B and delay in appropriate diagnostic studies and therapy.