Siderophore production of Klebsiella species isolated from different sources

A total of 481 Klebsiella pneumoniae and K. oxytoca strains isolated from different sources was examined for siderophore production. Screening for siderophore secretion by chrome azurol S agar revealed that 475 strains (98.8%) produced siderophores. The isolates were further investigated for synthesis of enterochelin and aerobactin by means of specific bioassays. Almost all Klebsiella strains (99.4%) excreted enterochelin. Aerobactin production, however, was rarely observed among K. pneumoniae (6%) and K. oxytoca (4%) isolates. The incidence of aerobaction-positive strains was similar in clinical, fecal, and environmental isolates. These results suggest that the aerobactin system does not represent a major mechanism of iron supply in Klebsiella spp.