HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by MAKAKOLE, S. C. Articles by STURM, A. W. Search for Related Content PubMed PubMed Citation Articles by MAKAKOLE, S. C. Articles by STURM, A. W. Agricola Articles by MAKAKOLE, S. C. Articles by STURM, A. W.

The effect of temperature on the interaction of Haemophilus ducreyi with human epithelial cells

Department of Medical Microbiology and MRC Genital Ulcer Disease Research Unit, Faculty of Medicine, University of Natal, Durban, South Africa

Corresponding author: Professor A.W. Sturm (e-mail: sturm{at}med.und.ac.za).

Received 19 June 2000; revised version received 11 Aug. 2000; accepted 23 Aug. 2000.

Abstract

To investigate if temperature affects the interaction of Haemophilus ducreyi with human epithelial cells, nine strains were used to evaluate the adhesion kinetics of the organism at 33°C and 37°C. The effect of the free toxin on the epithelial cells at those temperatures was also assessed. The cyto-adherence kinetics of H. ducreyi to the epithelial cells was significantly greater at 33°C (10 times more) than at 37°C in all seven clinical isolates tested. There was a significant difference in cell-associated H. ducreyi at 33°C as compared with 37°C. Control strains showed similar adhesion properties at both temperatures. However, the virulent strain CIP542 adhered in larger amounts than the avirulent strain A77. Electron microscopy revealed that there was more tissue necrosis at the lower than the higher temperature. The effect of the free toxin was the same at each temperature. However, strain A77 had significantly lower toxicity than strain CIP542 and the clinical isolates. These results suggest that H. ducreyi displays a temperature-dependent interaction with human epithelial cells, and this feature may play a role in the virulence of the organism in vivo. While the overall toxic effect of viable bacteria depends on the metabolic activity of the bacteria and is, therefore, higher at 33°C than at 37°C with the same initial inoculum, the effect of the extracted toxin at molecular level with fixed concentrations is a temperature-independent event.