Bloodgroup simulating activity in aerobic gram-negative oral bacteria cultured from fresh corpses

The gram-negative aerobic oral bacterial flora of 100 consecutive corpses was isolated. After the identification and culturing of the isolated organisms, blood grouping was performed by the haemagglutination inhibition technique on dried culture smears, the dried culture medium and a dried ethanol extract of the bacteria. Forty-seven of the samples showed a gram-negative aerobic bacterial growth, giving 58 microorganisms of 14 different species. Positive blood grouping results were found in two of them (Escherichia coli and Serratia marcescens), both of type B. It is concluded that occasional mistyping of blood groups on saliva and oral material may be caused by the oral gram-negative aerobic flora, especially if the specimens are contaminated or putrefying.