Isolation and identification of Haemophilus ducreyi in a clinical study

Abstract

Seventeen strains of Haemophilus ducreyi were isolated from genital lesions which were negative for syphilis by dark-field examination. Media used for primary isolation at various times during the study were enriched chocolate agar, chocolate agar plus vancomycin (3 microgram/ml), rabbit blood agar plus vancomycin (3 micrograms/ml), fetal bovine serum agar, and fetal bovine serum agar plus vancomycin (3 micrograms/ml). H. ducreyi was isolated on chocolate agar plus vancomycin from 10 of 14 patients found to be positive on one or more media, on rabbit blood agar plus vancomycin from 16 of 17 patients, and on fetal bovine serum agar plus vancomycin from 9 of 11 patients. Sera from six animal species were tested to determine if any would support the growth of H. ducreyi. Horse and rabbit sera supported light growth of some strains. Fetal bovine serum supported good growth of all strains included in the study. Biochemical and physiological tests were done on the 17 isolates, a reference strain of H. ducreyi, and two reference strains of Haemophilus haemoglobinophilus. The results agreed with those reported by Kilian, except that H. ducreyi produced alpha-hemolysis in stabs on rabbit blood agar and was oxidase positive, three strains were urease positive, and CO2 improved the growth of seven strains. All 17 isolates were beta-lactamase positive. The reference strains were beta-lactamase negative.

Enhanced recovery of Haemophilus ducreyi from clinical specimens by incubation at 33 versus 35 degrees C

“…To improve isolation rates, most attention has focused on the adequacy of media. Many media have been devised for the culture of H. ducreyi, and differences in recovery rates between culture media have been well described (5,6,21).…”

“…The role of adequacy of culture conditions in primary isolation has been studied far less than the adequacy of the media. With stocked strains, added moisture and CO 2 have been shown to enhance growth (1,21,22), but the effect of these parameters on primary isolation has not been investigated. Similarly, with stocked strains, 33ЊC was shown to be better for growth than 22, 37, or 42ЊC (22), but the effect of temperature on primary isolation has not been investigated.…”

“…As a result of these studies, added moisture and CO 2 are routinely recommended culture conditions, but the incubator temperature is far less standardized, and workers spanning a 40-year period have variously recommended temperatures from 28 to 37ЊC (1,18,19,22). Current texts recommend 33 to 35ЊC (3), while workers in the field use 33ЊC (7,14,23), 34ЊC (1,2,12,15), 33 to 35ЊC (5, 10), 34 to 36ЊC (8), 37ЊC (4), and, most commonly, 35ЊC (6,9,11,16,20,21,24).…”

The rabbit antibody response to immunization with Haemophilus ducreyi A comparative study for immunoglobulin detection using diffusion-in-gel enzyme-linked immunosorbent assay, countercurrent immunoelectrophoresis, and double-diffusion-in-gel

“…Genital ulcers can be caused by a wide variety of agents including Haemophilus ducreyi, Herpes simplex virus, and Treponema pallidum [1]. Demonstration of H. ducreyi as the causative agent often fails due to several factors; the microorganisms are sensitive to transportation, need selective media to grow, and are easily overgrown by other microorganisms often present in genital ulcers [1,2]. Furthermore, direct microscopy of Gram-stained pus is nonspecific [2].…”

“…Many attempts have been made to improve the possibilities to isolate H. ducreyi from genital ulcers, e.g. by improvement of transportation conditions and by using a number of different media for cultivating H. ducreyi [1,2]. However, the resuits have been anything but encouraging.…”