Antimicrobial susceptibility and characterization of outer membrane proteins of Haemophilus ducreyi isolated in Thailand

Abstract

One hundred strains of Haemophilus ducreyi isolated in Thailand from patients with chancroid were tested by the agar dilution method against 10 antimicrobial agents and typed by outer membrane protein pattern by using sodium dodecyl sulfate gel electrophoresis. All strains produced beta-lactamase and were resistant to tetracycline, kanamycin, and sulfonamides. Most had a decreased susceptibility to trimethoprim (MIC for 50% of the strains [MIC50], 0.5 ,ig/ml) and chloramphenicol (MIC50, 8 ,ug/ml). Strains were susceptible to ciprofloxacin (MIC90, 0.001 ,ug/ml), ceftriaxone (MIC50, 0.0015 ,ug/ml), erythromycin (MIC50, 0.015 ,ug/ml), rosoxacin (MIC50, 0.03 ,ig/ml), and spectinomycin (MIC50, 8 ,ug/ml). The degree of antimicrobial resistance found in Thailand is higher than that reported for H. ducreyi isolated in other regions. Five different outer membrane protein patterns were found by analyzing proteins in the range of 29 to 61 kilodaltons, but 98% of the Thai strains fell into three patterns which did not differ greatly. Outer membrane protein patterns of Thai strains were also seen in strains from other geographic areas. A new outer membrane protein type was found among nine strains isolated in Singapore.

Chancroid and Haemophilus ducreyi.

“…2) have shown that the outer membrane of H. ducreyi appears morphologically similar to those of other gram-negative bacteria (82). The outer membrane protein profile is also typical of gram-negative bacteria, with one to several proteins predominating (1,115,145,164). Typical outer membrane protein profiles for H. ducreyi are shown in Fig.…”

“…Most of the published studies have used the agar dilution method (18,21,51,53,61,75,123,151,155,164,165) to determine the antimicrobial susceptibility of H. ducreyi. However, disk diffusion (27,53) and broth microdilution (84) techniques have also been used.…”

“…There is no standard medium for performing antimicrobial susceptibility tests on H. ducreyi. Enriched GC agar (21,61,123), enriched Mueller-Hinton agar (27,51,151,164), Beiling medium with Mueller-Hinton agar instead of Columbia agar (155), and Sheffield medium (75) have all been used. For this reason, it is often difficult to compare the MICs obtained in different studies.…”

“…REV. 150 MORSE high frequency of kanamycin-resistant strains were reported from Thailand (164). Sanson-Le Pors et al (142) observed that streptomycin and kanamycin resistance was associated with a 3.07-MDa plasmid (Table 9).…”

Ribosomal DNA typing of Haemophilus ducreyi strains: proposal for a novel typing scheme

“…There has been a renewed interest in chancroid since it was shown to be a risk factor for the transmission and acquisition of human immunodeficiency virus (1,13). Until recently, the typing of H. ducreyi strains relied on phenotypic characteristics, viz., outer membrane protein profiles (5,11), lectin typing (4), immunotyping (8), and enzyme profiles (12). In view of the homogeneity of H. ducreyi strains, these techniques are of limited use (3).…”