Microbiological status of commercially available medicinal herbal drugs--a screening study

One hundred and thirty-eight medicinal herbal drugs obtained from different suppliers were examined for microbial contaminants and for the detectability of pathogenic microorganisms. For this purpose, several microbiological standard parameters (total aerobic mesophilic count, enterobacteria, coliforms, aerobic sporeformers, yeasts and moulds, enterococci, lactobacilli, pseudomonades and aeromades) and selective methods for the detection of indicator microorganisms and pathogens (E. coli, enterohaemorrhagic E. coli [EHEC], Salmonella, Campylobacter jejuni, Pseudomonas aeruginosa, Bacillus cereus, Clostridium perfringens, Listeria, coagulase-positive staphylococci, Candida albicans, potentially aflatoxigenic moulds) were applied. The microbial load of the samples varied considerably. While none of the samples contained EHEC, Salmonellae, Pseudomonas aeruginosa, Listeriae, Staphylococcus aureus or Candida albicans, four samples were E. coli positive, two samples were presumptively Campylobacter jejuni positive and nine herbal drugs contained a potentially aflatoxigenic mould flora. Further details regarding different viable count classes as well as preparation techniques are discussed.