Detection of bacteria in the presence of antibiotics by using specific monoclonal antibodies to neutralize the antibiotics.

Inactivation of penicillin and gentamicin in cultures was achieved by using monoclonal antibodies against these antibiotics. A viridans group streptococcus (penicillin MIC, less than or equal to 0.06 micrograms/ml) and Escherichia coli ATCC 35218 (gentamicin MIC, less than or equal to 1 microgram/ml) were able to grow in broth containing 0.25 micrograms of penicillin per ml and 4 micrograms of gentamicin per ml, respectively, when the specific antibodies were added. This procedure may be useful to increase the yield of bacteria from body fluid specimens that contain antibiotics.