Clostridium botulinum spores in Polish honey samples

Abstract

The aim of this study was an examination of 240 multifloral honey samples collected from Polish apiaries to determine Clostridium botulinum occurrence. Honey was collected from apiaries directly after the extraction process. Samples were inoculated by using the dilution and centrifugation method. Suspected isolates were examined by using mouse bioassay, polymerase chain reaction (PCR), and real-time PCR methods. C. botulinum type A and B strains were detected in 5 of 240 examined honey samples (2.1%). Bacterial strains were also detected that were phenotypically similar to C. botulinum but that did not exhibit the ability to produce botulinum toxins and did not show the presence of the botulinum cluster (ntnh and bont genes) or expression of the ntnh gene. The methods used in the examination, especially the expression analysis of ntnh gene, enabled specific analysis of suspected strains and could be used routinely in environmental isolate analyses of C. botulinum occurrence.

Keywords: Clostridium botulinum; Polish apiaries; honey; neurotoxins.

Fig. 1. Relative expression of the ntnh gene from Clostridium botulinum isolates. Fold changes obtained after expression analysis of ntnh gene for isolates from samples 16, 24, 139, 143, and 144 in relation to the C. botulinum NCTC 887 reference strain. The highest expression level for C. botulinum isolate was from sample 139 and was calculated as a 181.01-fold change. The lowest expression was noticed for an isolate from sample 144 and equaled a −1.86-fold change.