Journal Article

Antimicrobial activity of SMAP-29 against the <i>Bacteroides fragilis</i> group and clostridia

Alessandra Arzese, Barbara Skerlavaj, Linda Tomasinsig, Renato Gennaro and Margherita Zanetti

in Journal of Antimicrobial Chemotherapy

Published on behalf of British Society for Antimicrobial Chemotherapy

Volume 52, issue 3, pages 375-381
Published in print September 2003 | ISSN: 0305-7453
Published online September 2003 | e-ISSN: 1460-2091 | DOI:
Antimicrobial activity of SMAP-29 against the Bacteroides fragilis group and clostridia

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Objectives: The cathelicidin-derived peptide SMAP-29 exerts rapid and broad-spectrum antimicrobial activity against aerobic bacteria and fungi. In this study, the effects of the peptide against the Bacteroides fragilis group, including antibiotic-resistant isolates, Clostridium perfringens and Clostridium difficile reference and clinical isolates, were investigated.

Methods: The microbicidal activity of SMAP-29 against eight reference and 100 clinical anaerobic strains from a national collection was assessed using a microdilution susceptibility assay, and by determining the killing kinetics on selected strains. The killing mechanism was investigated further by means of a two-colour fluorescent permeabilization assay, and by scanning electron microscopy (SEM).

Results: The Bacteroides fragilis group, Clostridium reference strains and most clinical isolates were inhibited in vitro by 1–2 µM (3.2–6.4 mg/L) SMAP-29, and killed by 1.5- to 2-fold higher peptide concentrations. The anaerobic bacterial cells were 90%–100% permeabilized within 2 h of exposure to bactericidal concentrations of the peptide. The SEM images of bacteria exposed to SMAP-29 provide morphological evidence that the envelope is an important target of the bactericidal activity of this peptide. These results are consistent with earlier studies indicating that SMAP-29 kills aerobic bacteria with a membranolytic mechanism, and suggest that both aerobic and anaerobic bacteria share surface features that are targeted by this peptide.

Conclusions: These studies demonstrate that the spectrum of antibacterial activity of SMAP-29 includes the B. fragilis group and Clostridium species, and encourage further investigations of the therapeutic potential of this peptide.

Keywords: Keywords: antimicrobial peptide, cathelicidin, anaerobic bacteria, membrane permeabilization

Journal Article.  4462 words.  Illustrated.

Subjects: Medical Oncology ; Critical Care

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