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Open Access Research article

Differential activity of innate defense antimicrobial peptides against Nocardia species

Siegbert Rieg1*, Benjamin Meier1, Eva Fähnrich1, Anja Huth1, Dirk Wagner1, Winfried V Kern1 and Hubert Kalbacher2

Author Affiliations

1 Center for Infectious Diseases & Travel Medicine, University Medical Center, Hugstetter Strasse 55, 79106 Freiburg, Germany

2 Medical and Natural Sciences Research Center, University of Tübingen, Ob dem Himmelreich 7, 72074 Tübingen, Germany

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BMC Microbiology 2010, 10:61  doi:10.1186/1471-2180-10-61

Published: 23 February 2010

Abstract

Background

Members of the genus Nocardia are ubiquitous environmental saprophytes capable to cause human pulmonary, disseminated and cutaneous nocardiosis or bovine mastitis. Innate immunity appears to play an important role in early defense against Nocardia species. To elucidate the contribution of antimicrobial peptides (AMPs) in innate defense against Nocardia, the activity of human α-defensins human neutrophil peptides (HNPs) 1-3, human β-defensin (hBD)-3 and cathelicidin LL-37 as well as bovine β-defensins lingual and tracheal antimicrobial peptides (LAP, TAP) and bovine neutrophil-derived indolicidin against four important Nocardia species was investigated.

Results

Whereas N. farcinica ATCC 3318 and N. nova ATCC 33726 were found to be susceptible to all investigated human and bovine AMPs, N. asteroides ATCC 19247 was killed exclusively by neutrophil-derived human α-defensins HNP 1-3 and bovine indolicidin. N. brasiliensis ATCC 19296 was found to exhibit complete resistance to investigated human AMPs and to be susceptible only to bovine indolicidin.

Conclusion

Selected AMPs are capable to contribute to the first line of defense against Nocardia, yet, susceptibility appears to vary across different Nocardia species. Obtained results of neutrophil-derived AMPs to possess the broadest antinocardial spectrum are remarkable, since nocardiosis is characterized by a neutrophil-rich infiltrate in vivo.