PubMed Health⌕ Search

Biomedical subjects

R C Ballard

Publications and source records attributed to R C Ballard.

At least 19 recordsLinked to original sources
PubMed1997

Comparison of clinical diagnosis and standard laboratory and molecular methods for the diagnosis of genital ulcer disease in Lesotho: association with human immunodeficiency virus infection.

A multiplex polymerase chain reaction (M-PCR) assay for Haemophilus ducreyi, Treponema pallidum, and herpes simplex virus (HSV) was compared with clinical and standard laboratory methods for the diagnosis of genital ulcer disease (GUD) in 105 patients; 36% were human immunodeficiency virus (HIV)-seropositive. Chancroid (80%), syphilis (8%), and genital herpes (8%) were the most frequent diagnoses. H. ducreyi and HSV were isolated from ulcers of 43% and 18% of patients, respectively; in 35%, all cultures were negative and the laboratory diagnosis indeterminate. M-PCR detected H. ducreyi, T. pallidum, and HSV in 56%, 23%, and 26% of patients, respectively; (no definitive diagnosis, 6%). The proportion of patients with more than one agent was 4% by culture and 17% by M-PCR (P = .002). Resolved sensitivities of M-PCR for H. ducreyi and HSV cultures were 95% and 93%, respectively. The sensitivities of H. ducreyi and HSV cultures were 75% and 60%, respectively. HSV, detected in 47% of specimens from HIV-infected versus 16% from HIV-uninfected patients (P < .001), may be emerging as a more frequent cause of GUD.

Adolescent↗
PubMed1997

An evaluation of the capillus HIV-1/HIV-2 latex agglutination test using serum and whole blood.

The capillus HIV-1/HIV-2 latex agglutination (LA) test was evaluated for its potential as an initial screening test in primary health care. For the serum study, panels totalling 289 HIV-positive sera and 323 known HIV-negative sera plus 50 individual seroconversion samples were tested by capillus. Paired blood specimens were also collected in heparinized and plain tubes from 501 consecutive patients with newly diagnosed sexually transmitted diseases (STDs) attending an STD clinic at a Transvaal hospital. Overall, an initial sensitivity of 99.3% and an initial specificity of 99.7% were obtained by visual reading of the capillus HIV-1/ HIV-2 LA tests on serum samples. Capillus also detected 40 (80%) of the 50 seroconversion samples. Of the 501 paired plain and heparinized blood specimens, serum testing by enzyme immunoassay (EIA) and indirect immunofluorescence/ Western blot (IFA/WB) showed 147 (29%) to be HIV Ab positive. Capillus testing of the paired specimens correctly identified all 147 known positive patients and 345 of the 346 negative patients, thus showing an initial sensitivity of 100% and an initial specificity of 99.7% for the testing of heparinized whole blood by a relatively unskilled health worker. It was concluded that the capillus HIV-1/HIV-2 LA test would be suitable for use as a primary screening test in small outlying laboratories or primary health care clinics.

Blotting, Western↗
PubMed1997

Immunohistochemical investigations of genital ulcers caused by Haemophilus ducreyi.

To gain information on the specific composition of the inflammatory infiltrate of genital ulcers caused by Haemophilus ducreyi, biopsies of 6 genital ulcers which were diagnosed as chancroid on clinical and microbiological grounds were subjected to immunohistochemical investigations after conventional haematoxylineosin staining. A variety of antibodies reactive against B- and T-cells, plasma cells and granulocytes were used with each tissue sections. The lymphocytic infiltrate of chancroid ulcers consisted of both B- and T-lymphocytes and showed a cluster-like formation. B-lymphocytes were preferentially localized perivascularly in the middle layer, T-lymphocytes mainly in the deep layer of the inflamed oedematous tissue. Results stress the importance of both B- and T-cell mediated immune responses in Haemophilus ducreyi infection.

Antibodies, Bacterial↗
PubMed1996

Sexually transmitted diseases in South Africa.

AIM: To review the epidemiology of and data collection for sexually transmitted diseases (STDs) in South Africa. METHODS: Literature published since 1980 on STDs in South Africa were complied and evaluated. Historical reports and salient unpublished literature were also used in the literature review. Studies were critically reviewed in the light of sample populations and study methods, and a baseline picture of the patterns of STD burden was developed. RESULTS: The STD burden in apparently asymptomatic study populations is significant. Ulcerative infections, primarily caused by syphilis and chancroid, are present in 5-15% of asymptomatic clinic attenders; prevalence rates of gonorrhoea average 8%, with up to 13% of gonococcal isolates resistant to penicillin antibiotics. In addition, on average, chlamydia and vaginal infections are detected in 16% and 20-49%, respectively, of antenatal and family planning clinic attenders. HIV seroprevalence rates have reached 7.6% in antenatal clinic attenders. Most South African STD data are derived from ad hoc surveys which have traditionally focused only on several major infections and particular urban centres. Almost all STD studies have been facility-based, with many studies based at STD clinics, thus reporting only relative frequencies and not population-based prevalences of STDs. With the possible exception of HIV, systematic surveillance data for STDs are conspicuously lacking. CONCLUSION: The disease burden of classic sexually transmitted infections has historically been heavy, and continues to be a serious public health problem in South Africa. Morbidity from both ulcerative and non-ulcerative infections, particularly in women, is significant. The body of STD data, although mostly sound, remains incomplete, and with the rapid emergence of HIV in South Africa, surveillance of STDs and focused STD policies will be critical.

Chancroid↗
PubMed1996

Treatment of chancroid with azithromycin.

A randomized, comparative study undertaken in Nairobi, Kenya and a non-comparative evaluation undertaken in Carletonville, South Africa have both shown that a single oral dose of azithromycin 1 g is effective in the treatment of the genital ulcer disease (GUD), chancroid, with cure rates of 89% and 92% recorded respectively. While treatment failure was associated with human immunodeficiency virus seropositivity and lack of circumcision in Kenya, no such association could be found in the South African study. In both series, azithromycin treatment resulted in cure of both Haemophilus ducreyi culture-positive and culture-negative cases of GUD, including two cases subsequently diagnosed as lymphogranuloma venereum. A combination of single-dose azithromycin with single-dose benzathine penicillin may provide effective 'single-visit' syndromic treatment for GUD in many developing countries.

Anti-Bacterial Agents↗
PubMed1996

Chancroid.

Explore the source record for details and available documents.

Anti-Bacterial Agents↗
PubMed1995

Specificity of the immune response to Haemophilus ducreyi.

The specificity of the antibody response to Haemophilus ducreyi in sera from patients attending a sexually transmitted disease clinic in South Africa has been studied using immunoblotting. Patients with chancroid were shown to have higher levels of IgG (mean 0.74, SD 0.34) to H. ducreyi than those with no history of chancroid (mean 0.34, SD 0.19). The pattern of the antibody specificity was highly variable between patients with culture proven chancroid but there was no observed strain specificity. In comparison, the patterns obtained using sera from patients without known exposure to H. ducreyi showed less variation between patients and were of less intensity at the dilution used. Sera from patients with chancroid recognised epitopes on proteins that varied in molecular weight between strains, particularly of 60-66kDa (10 of 36 patients) and 25-27kDa (8 of 36 patients). In addition epitopes were recognised on the GroEL and/or DnaK heat shock proteins in 13 of 36 sera tested. There was no apparent change in the epitopes recognised on proteins between the homologous and heterologous strains. Patterns of antibody specificity in sequential sera only varied in one of six patients tested.

Antibodies, Bacterial↗
PubMed1995

Simplified PCR for detection of Haemophilus ducreyi and diagnosis of chancroid.

A simplified PCR was developed for detection of Haemophilus ducreyi in samples from chancroid patients. The strategy included a straightforward chloroform extraction sample preparation method, a one-tube nested PCR to minimize contamination risks, and a colorimetric method for detection of products. Primers were designed from published nucleotide sequences of the 16S rRNA gene of H. ducreyi, with longer outer primers for annealing at a higher temperature and shorter inner primers labelled with biotin and digoxigenin for binding with avidin and colorimetric detection. The PCR technique detected all 35 strains of H. ducreyi tested, from four different geographical regions, and was negative for other, related strains of bacteria and for the common contaminating bacteria tested. Of 25 samples from H. ducreyi culture-positive chancroid patients, 24 were PCR positive and 1 produced a weak reaction. Of 83 samples from clinical cases of chancroid in the Republic of South Africa, 69 were PCR positive. The sensitivity of PCR compared with that of clinical diagnosis was 83%. All 50 negative control samples were negative. Encouraging results were also obtained with a consecutive series of 25 genital ulcer patients in Tanzania, of whom 9 were PCR positive. The adaptations of this simplified PCR strategy, at the sensitivity and specificity levels obtained, mean it will be useful for detection of H. ducreyi in areas where the organism is endemic, particularly where testing by culture is difficult or impossible.

Base Sequence↗
PubMed1995

Characterisation of penA and tetM resistance genes of Neisseria gonorrhoeae isolated in southern Africa--epidemiological monitoring and resistance development.

OBJECTIVE: To investigate penA and tetM resistance gene variation of Neisseria gonorrhoeae in order to define gene types for epidemiological monitoring and resistance development. DESIGN: Isolates of N. gonorrhoeae which were susceptible and resistant to penicillin and/or tetracycline were selected. Strains comprised South African isolates (22 from Bloemfontein, 13 from Transvaal, 20 from the Cape) and 15 Botswana and 4 Namibia isolates. The penA genes (2 kb) of all strains and tetM genes (765 bp) of 11 high-level tetracycline-resistant strains were amplified and restricted with HpaII. RESULTS AND CONCLUSIONS: Twelve different HpaII fingerprint patterns were obtained from the 74 isolates analysed for penicillin-binding protein (PBP) 2 gene (penA) alterations. Focusing on the transpeptidase domain, 25 isolates (3 whole gene patterns, minimal inhibitory concentrations (MICs) < or = 0.03-0.125 micrograms/ml) had restriction sites equivalent to those previously described for a susceptible strain. Of the remaining 9 PBP 2 gene groups, 25 strains fell into a designated group E. Penicillin/ penicillin + clavulanic acid MICs determined on these group E isolates gave a range of 0.125-2.0 micrograms/ml, although MICs against 4 strains were < or = 0.03 micrograms/ml. MICs of penicillin/penicillin + clavulanic acid for the 24 isolates that contained altered PBP 2 transpeptidase gene regions not designated group E were only < or = 0.03-0.125 micrograms/ml. The lack of a HpaII restriction site at nucleotide 1934 in the PBP 2 gene of group E strains was indicative of a small terminal region of N. cinerea DNA. This gene block, which was found in all the southern African areas studied, appears to predispose isolates to increased penicillin resistance. The 25.2 MDa conjugative plasmid carrying the tetM resistance determinant was readily demonstrated in 11 Botswana/Namibia isolates exhibiting high-level resistance to tetracycline (MICs > or = 16 micrograms/ml). The tetM gene was shown to be of the American type.

Drug Resistance, Microbial↗
PubMed1992

A simple medium for the primary isolation of Haemophilus ducreyi.

Two simple, inexpensive media containing gonococcal agar-base, supplemented with 5% Fildes' extract and either chocolated or unchocolated horse blood (GC-FHBC or GC-FHB) were compared with the standard gonococcal agar-based (GC-HgS) and Mueller-Hinton agar-based media (MH-HB) normally used for primary isolation of Haemophilus ducreyi from presumptive chancroid lesions. Overall, Haemophilus ducreyi was recovered from 162 of 178 (91%) samples from primary chancroid lesions. As a single isolation medium GC-HgS proved the most sensitive with an isolation rate of 80% followed by GC-FHB (75%), MH-HB and GC-FHC (both 71%). Use of a combination of GC-HgS and MH-HB resulted in isolation of Haemophilus ducreyi in 160 of 178 cases (90%). Since GC-FHB is approximately one-quarter the cost of the combination and half the cost of GC-HgS or MH-HB alone, this medium could prove suitable for diagnostic purposes in developing countries where chancroid is endemic.

Agar↗
PubMed1992

Lack of immunoglobulin A1 protease production by Haemophilus ducreyi.

A collection of 20 strains of Haemophilus ducreyi including freshly isolated, low-passage and multi-passage reference strains was examined for immunoglobulin A1 protease production by SDS-PAGE and immunoblotting. None of the strains demonstrated IgA1 protease activity despite the fact that different culture media were used. By direct immunofluorescence testing, binding of IgA to Haemophilus ducreyi organisms could be demonstrated.

Blotting, Western↗
PubMed1992

A serological test for granuloma inguinale.

OBJECTIVES: An indirect immunofluorescence technique applied to paraffin embedded tissue sections of lesions containing Donovan bodies was evaluated as a serological test for the diagnosis of granuloma inguinale. METHODS: Sera from patients with proven granuloma inguinale, other sexually acquired genital ulcerations and blood donors from areas where granuloma inguinale is rarely encountered as well as from disease-endemic regions were tested. Sera were tested either unabsorbed or following absorption with whole Klebsiella pneumoniae bacteria. RESULTS: Using unabsorbed sera at a dilution of 1:160 the test was found to have a sensitivity of 100%, specificity of 98%, positive predictive value (PPV) of 89% and negative predictive value (NPV) of 100%. There proved to be no advantage in preabsorbing sera with K. pneumoniae antigen. CONCLUSIONS: In the absence of culture methods for Calymmatobacterium granulomatis, an indirect immunofluorescence technique may prove valuable for the diagnosis of individual cases of granuloma inguinale and as an epidemiological tool in studies of the disease.

Antibodies, Bacterial↗
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↗