Combined Bacillus licheniformis and Bacillus subtilis infection in a patient with oesophageal perforation

Species of the genus Bacillus are a common laboratory contaminant, therefore, isolation of these organisms from blood cultures does not always indicate infection. In fact, except for Bacillus anthracis and Bacillus cereus, most species of the genus Bacillus are not considered human pathogens, especially in immunocompetent individuals. Here, we report an unusual presentation of bacteraemia and mediastinitis due to co-infection with Bacillus subtilis and Bacillus licheniformis, which were identified by 16S RNA gene sequencing, in a patient with an oesophageal perforation.