RT Journal Article SR Electronic T1 The influence of penicillin on Lactobacillus leichmannii serum B12 assay JF Journal of Clinical Pathology JO J Clin Pathol FD BMJ Publishing Group Ltd and Association of Clinical Pathologists SP 189 OP 192 DO 10.1136/jcp.14.2.189 VO 14 IS 2 A1 Boczarow, Borys YR 1961 UL http://jcp.bmj.com/content/14/2/189.abstract AB The influence of penicillin on vitamin B12 assay using L. leichmannii as the test organism was investigated, and it was found that penicillin even in a low serum concentration invalidated the test.