An Unusual Autopsy Case in Which the Consumption of Organophosphate Insecticide Was Not the Direct Cause of Death

In acute poisoning cases involving the ingestion of organophosphate insecticides such as fenitrothion and malathion, serum cholinesterase (ChE) activity is remarkably decreased, thus representing a useful indicator of the direct cause of death. In the present case, a man in his early 70s tried to committed suicide via the oral ingestion of both fenitrothion and malathion. Fenitrothion and malathion concentrations in cardiac blood were 2.63–2.98 and 0.31–0.58 µg/mL, respectively. However, the serum ChE level was 200 IU/L, which was not considerably lower than the normal range in males (242–495 IU/L). Conversely, we confirmed a positive reaction for Streptococcus pneumoniae using a urinary antigen detection kit. Moreover, histopathological analysis of both the left and right lungs revealed extensive inflammatory cell infiltration into the alveolar space. The autopsy and histopathological findings indicated that the direct cause of death was severe bacterial pneumonia caused by the infection of S. pneumoniae. This is an unusual autopsy case in which the oral ingestion of both fenitrothion and malathion was not the direct cause of the death, and might have rapidly exacerbated respiratory decline.