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Biomedical subjects

R C Ballard

Publications and source records attributed to R C Ballard.

At least 55 records · Page 3Linked to original sources
PubMed1991

Absence of extracellular enzyme activity and cytotoxicity in cell-free culture filtrates of Haemophilus ducreyi.

Ten isolates of Haemophilus ducreyi, including seven clinical isolates and three laboratory reference strains, were assessed for their ability to produce extracellular enzymes which might contribute to their pathogenicity. Protease, elastase, lecithinase, lipase or collagenase enzyme activity were not detected in culture filtrates from any of the isolates tested using either plate or spectrophotometrical assays. Furthermore, cell-free culture filtrates did not exhibit cytotoxic activity in vitro when tested using either an established tissue culture cell line (Vero) or a primary cell culture of human keratinocytes. These results suggest that extracellular products do not play a role in host invasion or production of tissue damage by H. ducreyi.

Cell-Free System↗
PubMed1991

Syphilis serology in patients with primary syphilis and non-treponemal sexually transmitted diseases in southern Africa.

The reactivity of a non-specific reagin (RPR) test and a specific treponemal (FTA-ABS) test were determined in 21 patients with primary syphilis, 430 patients with proven non-treponemal genital ulcerations and 719 patients with acute urethritis presenting at a clinic for sexually transmitted diseases in southern Africa. Excluding those 21 cases of primary syphilis, 358 of 1149 tests performed (31%) were found to be reactive by at least one test. The rate of false positive RPR tests was very low (0.02%). Significantly higher rates of seropositivity were detected in patients with genital ulcerations than in patients with acute urethritis. The highest rates were detected among patients with proven lymphogranuloma venereum (34% RPR positive, FTA-ABS positive; 19% RPR negative, FTA-ABS positive). The geometric mean titres (GMT) of positive RPR tests in non-treponemal infections were found to be lower than in darkfield positive cases of genital ulcer disease.

Acute Disease↗
PubMed1990

A comparative study of spectinomycin and erythromycin in the treatment of chancroid.

In a randomized, controlled study, 55 patients with genital ulcerations, culture-positive for Haemophilus ducreyi, were treated with a single intramuscular injection of 2 g spectinomycin. A further 61 patients were treated with a five-day oral course of erythromycin base (500 mg, three times daily). Treatment failure occurred in seven patients who received spectinomycin (13%), whilst no treatment failures were recorded among patients who received erythromycin. This difference in efficacy was statistically significant. In contrast, spectinomycin proved significantly more effective than erythromycin in the treatment of the lymphadenopathy associated with primary chancroid lesions.

Administration, Oral↗
PubMed1990

Soluble interleukin-2 receptors in serum and urine of patients with chancroid and their response to therapy.

To investigate cell-mediated immune response in chancroid, soluble interleukin-2 receptor levels in serum and urine samples of healthy individuals and patients were measured by an enzyme-linked immunosorbent assay. Increased levels both in serum and in urine were observed in cases of Haemophilus ducreyi infection. In patients showing a prolonged incubation period, urine levels exceeded serum values. Therapy led to a reduction of elevated interleukin-2 receptor levels in serum and in urine.

Chancroid↗
PubMed1990

Characterization of skin lesions in mice following intradermal inoculation of Haemophilus ducreyi.

Twelve strains of H. ducreyi, which included two reference strains, were each inoculated intradermally into the flanks of CBA mice. All strains produced self-limited lesions which were macroscopically and microscopically typical of those seen in chancroid. Pustular nodules, about 5mm in diameter, developed at all inoculation sites by the second day when 10(7) organisms were inoculated. Approximately half of these lesions ulcerated and all had regressed by 2 weeks. Smaller nodules developed at about half the sites from the second to the fifth day when 10(6) or 10(5) organisms were given, but these did not ulcerate. No lesions were seen when 10(3) organisms were inoculated. Organisms were recovered from the lesions up to 11 days after inoculation. Specific H. ducreyi antigen, sought by a monoclonal antibody test, was detected in lesions up to 15 days following inoculation. Heat-killed organisms of H. ducreyi also produced nodules and ulcers although these were slightly smaller than those which developed after inoculation of viable bacteria. Similar lesions to those caused by H. ducreyi were produced after intradermal inoculation of about 10(8) viable or killed Neisseria gonorrhoeae organisms. Treatment of mice with ceftriaxone had little or no effect on the subsequent development of H. ducreyi-induced lesions. These findings indicated that the lesions were not produced specifically by viable H. ducreyi organisms. Ulcers were also produced following intradermal inoculation of purified lipopolysaccharide (LPS) from H. ducreyi or N. gonorrhoeae, but not by cell-free filtrates prepared from H. ducreyi cultures indicating a possible role for LPS in the pathogenesis of ulcerative skin lesions.

Animals↗
PubMed1989

Urinary recovery and tolerability of FCE 22101 following single intravenous administration under restricted and high fluid intake.

The urinary recovery and tolerability of FCE 22101, a broad spectrum injectable penem, were investigated in a multicentre single-blind randomized crossover study of 60 healthy male volunteers. Single 1 g doses of FCE 22101 or placebo were given by intravenous bolus at weekly intervals. FCE 22101 was given either after intake of 750 ml water (treatment A) or after 8 h of water restriction (treatment B). Placebo was given under water restriction (treatment C). Urine samples obtained at timed intervals were assayed for FCE 22101 and its metabolites P1 and P2 by HPLC. The 24 h urinary recoveries of the parent drug and its metabolites were similar after treatments A and B. Mean recoveries +/- S.D were 29 +/- 13% (FCE 22101), 31 +/- 12% (P1) and 7 +/- 2% (P2) of the dose. Transient suprapubic pain or dysuria, or both, were reported by two subjects after treatment A and by six subjects after treatment B. Symptoms were associated with low urine volumes at 0-2 h and low urinary recovery of FCE 22101 and metabolite P1.

Adult↗
PubMed1989

Review of the in-vitro evaluation of FCE 22101.

FCE 22101 is a broad spectrum beta-lactam displaying bactericidal properties, stable to a wide range of clinically relevant beta-lactamases, and sharing with other beta-lactams a modest post-antibiotic effect and synergistic interactions with aminoglycosides. The ability to administer the drug by oral and parenteral routes suggests that it could be clinically useful.

Anti-Bacterial Agents↗
PubMed1989

Treating chancroid: summary of studies in southern Africa.

Recent studies undertaken in southern Africa and elsewhere indicate that many short or single dose treatments are available to treat chancroid. Erythromycin 500 mg three times a day for five days, ciprofloxacin 500 mg, sulphamethopyrazine 800 mg and trimethoprim 1000 mg or sulphametrole 3200 mg and trimethoprim 640 mg as single oral doses, or ceftriaxone 250 mg as a single intramuscular injection are all effective in treating the disease. The widespread use of these regimens largely depends on the accuracy of diagnosis, susceptibilities of local Haemophilus ducreyi isolates to antimicrobials, and financial considerations.

4-Quinolones↗
PubMed1989

Rapid detection of Haemophilus ducreyi in clinical and experimental infections using monoclonal antibody: a preliminary evaluation.

A monoclonal antibody raised against Haemophilus ducreyi was tested for its sensitivity and specificity as an immunofluorescence (IF) reagent using simulated vaginal smears containing H. ducreyi, smears taken from skin lesions of mice infected with H. ducreyi and patients from South Africa, Thailand and Malaysia with clinically diagnosed chancroid. The IF test was more sensitive than culture or Gram staining in the simulated smears, theoretically detecting less than 4 organisms/sample. It detected H. ducreyi in 95% of the animal lesions compared with 14% detected by culture. Immunofluorescence testing identified over 90% of culture-positive cases of chancroid but also detected organisms in some culture-negative cases where clinical evidence for the diagnosis was strong. These results suggest that this antibody may provide a simple, rapid and sensitive means of detecting H. ducreyi in cases of chancroid.

Animals↗
PubMed1989

[Morphologic variants of genital ulcer caused by Haemophilus ducreyi].

The typical clinical picture, common variants and frequent complications of chancroid are presented in cases proven by culture. In general, the conventional view of the clinical spectrum of chancroid is substantiated. Certain types such as "chancre mou volant," however, could not be found in the present material. Their existence or association with Haemophilus ducreyi remains speculative.

Adult↗
PubMed1988

Lectin typing of Haemophilus ducreyi.

The cell wall carbohydrates of 43 strains of Haemophilus ducreyi isolated in different parts of the world were subjected to lectin analysis using commercial panels containing 14 different plant lectins of known specificity. Preliminary evidence indicated both intrastrain and inter-strain variation in cell wall carbohydrate composition. In addition, it was possible to group strains from different geographical areas by lectin agglutination patterns. Lectin typing might thus become a useful marker system for epidemiological investigation of Haemophilus ducreyi infections.

Agglutination↗
PubMed1988

Antibiotic susceptibilities and plasmid profiles of Haemophilus ducreyi isolates from southern Africa.

Thirty-eight strains of Haemophilus ducreyi isolated in southern Africa were tested in vitro against 15 antimicrobial agents including those frequently used for the treatment of chancroid. In addition, newer compounds which possess characteristics consistent with their possible use as single-dose therapy for the disease were tested. All isolates were found to be resistant to penicillin as a result of beta-lactamase production. The majority of strains were also resistant to tetracycline, sulphamethoxazole and trimethoprim, but susceptible to co-trimoxazole, erythromycin, spectinomycin, ceftriaxone, ceftizoxime, cefodizime, ciprofloxacin, fleroxacin, rifampicin, rifabutin and FCE 22250. beta-Lactamase production appeared to be associated with the presence of low molecular weight plasmids (5.7 or 7 Md). Sulphonamide resistance appeared to be either chromosomally-mediated or due to the presence of a 4.9 Md plasmid. No evidence of plasmid-mediated tetracycline resistance was observed.

Anti-Bacterial Agents↗
PubMed1988

In vitro activity of eight antimicrobial agents against non-penicillinase-producing gonococci isolated in Munich.

The susceptibility of 119 strains of Neisseria gonorrhoeae isolated in Munich in 1986 to eight antibiotics was assessed. Although some degree of resistance to penicillin and tetracycline, as well as high minimum inhibitory concentrations (MIC) of spectinomycin, were observed, all the strains were sensitive to ciprofloxacin, enoxacin, fleroxacin, cefotaxime, and FCE 22250.

Anti-Bacterial Agents↗
PubMed1986

In vitro activity of A-56619 (difloxacin), A-56620, and other new quinolone antimicrobial agents against genital pathogens.

The in vitro activities of two new carboxyquinolones, A-56619 (difloxacin) and A-56620, were compared with those of ciprofloxacin, norfloxacin, and ofloxacin against genital tract pathogens. All the quinolones were highly active against Neisseria gonorrhoeae. A-56619 had the lowest MICs against Chlamydia trachomatis (MIC range, 0.125 to 0.25 micrograms/ml) and Haemophilus ducreyi (MIC for 90% of isolates tested, 0.1 micrograms/ml).

Anti-Bacterial Agents↗