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Biomedical subjects

K A Haynes

Publications and source records attributed to K A Haynes.

13 recordsLinked to original sources
PubMed1998

Importance of Candida species other than Candida albicans as opportunistic pathogens.

Candida species other than C. albicans have become a significant cause of infection in humans. Several of the more commonly isolated of these species are less susceptible to commonly used azole antifungal drugs, a factor that poses significant difficulties for effective treatment. The modern mycology laboratory has an important role to play in several aspects relating to these organisms, including therapy, detection, identification and epidemiological analysis. The application of molecular techniques and phylogenetic analysis has led to the identification of a new species of Candida associated with mucosal candidiasis in HIV-infected individuals named Candida dubliniensis, the clinical significance of which is currently under investigation. Molecular techniques are also being applied to the analysis of determinants involved in pathogenicity of species such as Candida glabratta. These approaches should lead to a better understanding of these organisms and there ability to cause disease and should also provide more effective treatment.

AIDS-Related Opportunistic Infections↗
PubMed1996

Rapid identification of Candida albicans, C. glabrata, C. parapsilosis and C. krusei by species-specific PCR of large subunit ribosomal DNA.

A rapid PCR-based method for the identification of four Candida species is described. Primers to conserved sequences in the V3 region of large subunit rDNA were used to amplify DNA from C. albicans, C. glabrata, C. parapsilosis and C. krusei. The sequences were aligned and areas of non-concordance were used to design four species-specific forward primers. In a blind study of 82 yeast strains, four PCRs based on these primers correctly identified nine C. albicans, 18 C. glabrata, 13 C. parapsilosis and 18 C. krusei strains after gel electrophoresis of amplified DNA. Furthermore, of 17 other Candida strains (10 species) and seven strains from other yeast genera (Saccharomyces, Cryptococcus and Trichosporon) only one false positive amplification product (with C. dubliniensis) was seen. These PCRs offer a rapid alternative to conventional techniques for the identification of C. albicans, C. glabrata, C. parapsilosis and C. krusei.

Base Sequence↗
PubMed1995

Candida dubliniensis sp. nov.: phenotypic and molecular characterization of a novel species associated with oral candidosis in HIV-infected individuals.

Atypical oral Candida isolates were recovered from 60 HIV-infected and three HIV-negative individuals. These organisms were germ-tube-positive and produced abundant chlamydospores which were frequently arranged in triplets or in contiguous pairs. They belonged to C. albicans serotype A and had atypical carbohydrate assimilation profiles. Fingerprinting the genomic DNA of a selection of these organisms with the C. albicans-specific probe 27A and five separate oligonucleotides, homologous to eukaryotic microsatellite repeat sequences, demonstrated that they had a very distinct genomic organization compared to C. albicans and C. stellatoidea. This was further established by random amplified polymorphic DNA (RAPD) and karyotype analysis. Comparison of 500 bp of the V3 variable region of the large ribosomal subunit genes from nine atypical isolates and the corresponding sequences determined from C. albicans, C. stellatoidea, C. tropicalis, C. parapsilosis, C. glabrata, C. kefyr and C. krusei showed that they atypical organisms formed a homogeneous cluster (100% similarity) that was significantly different from the other Candida species analysed, but was most closely related to C. albicans and C. stellatoidea. These genetic data combined with the phenotypic characteristics of these atypical organisms strongly suggest that they constitute a novel species within the genus Candida for which the name Candida dubliniensis is proposed.

AIDS-Related Opportunistic Infections↗
PubMed1995

Involvement of multiple Cryptococcus neoformans strains in a single episode of cryptococcosis and reinfection with novel strains in recurrent infection demonstrated by random amplification of polymorphic DNA and DNA fingerprinting.

We compared the abilities of random amplification of polymorphic DNA and DNA fingerprinting, with oligonucleotide probes, to type five pairs of Cryptococcus neoformans clinical isolates recovered from five separate human immunodeficiency virus-positive patients in London, England. The two techniques had comparable discriminatory abilities when applied to these isolates. A total of eight different isolate types were demonstrated in these patients. No isolate type was observed in more than one patient. Two of the isolate pairs recovered from single episodes of cryptococcosis within 1 day of each other were genotypically indistinguishable by both methods. The other three pairs of isolates were all distinguishable. One of these isolate pairs was obtained from a single episode of cryptococcosis, while the other two were obtained from recurrent infections. These results indicate that multiple strains of C. neoformans may be responsible for a single episode of cryptococcosis and that recurrent infection may occur as a result of reinfection with a novel strain.

Base Sequence↗
PubMed1992

Rhinocerebral mucormycosis following bone marrow transplantation.

Rhizopus oryzae was the causative organism in a fatal case of rhinocerebral and then pulmonary mucormycosis in a patient cured of her underlying leukaemia by bone marrow transplantation. We discuss the risk factors involved and the need for maintaining a high index of suspicion of fungal infection in the late post-transplant period.

Adult↗
PubMed1990

Value of antigen detection in predicting invasive pulmonary aspergillosis.

Two ELISAs were used to detect serum and urinary aspergillus antigen in 121 patients who were profoundly neutropenic after leukaemia therapy or bone marrow transplantation. The presence of antigen correctly predicted development of invasive pulmonary aspergillosis (IPA) in 16 patients. In 2 other cases antigen appeared after the clinical diagnosis had been made, while in only 1 case was antigen not detected. In 11 of 13 episodes of clinically suspected fungal infection antigen was detected before clinical diagnosis was made. By contrast, antigen was detected in only 1 of 90 patients who had no evidence of IPA. Both ELISAs gave positive and negative predictive values for IPA of greater than 95%, demonstrating the value of antigen detection in early diagnosis of aspergillus infection and the assay's ability to predict subsequent development of IPA. We conclude that neutropenic patients should be screened for aspergillus antigen, and propose that initial detection of fungal antigen justifies commencement of empirical antifungal therapy. Such an approach should improve the survival of patients who are at risk of developing this usually fatal infection.

Adolescent↗
PubMed1990

Detection of Aspergillus antigens associated with invasive infection.

Serial urine samples were collected from 33 neutropenic patients, 10 of whom developed invasive aspergillosis (IA) while undergoing bone marrow transplantation or remission induction therapy for leukemia. Concentrated urine samples from the infected patients were subjected to polyacrylamide gel electrophoresis, blotted, and then incubated with antiserum raised to a cell wall extract of Aspergillus fumigatus (anti-CW) or an immunoglobulin G monoclonal antibody to A. fumigatus galactomannan (EBA1). When IA patient urine blots were probed with anti-CW, major bands at 11 and 18 kilodaltons (kDa); intermediate bands at 13, 14, and 29 kDa; and minor bands at 38 and 44 kDa were seen. In contrast, EBA1 showed diffuse staining at molecular masses larger than 45 kDa and a single weak band at 21 kDa. Urine samples from the 23 patients with no evidence of IA were unreactive with both anti-CW and EBA1. These antigen bands are likely to represent immunodominant antigens which are excreted during IA and should play a valuable role in the development of rapid diagnostic tests for aspergillosis.

Antibodies, Fungal↗
PubMedDate not supplied

Rapid detection and identification of pathogenic fungi by polymerase chain reaction amplification of large subunit ribosomal DNA.

We describe a polymerase chain reaction (PCR) based approach to the detection and identification of pathogenic fungi which has potential for the diagnosis of systemic mycoses. Primers to sequences of the large subunit ribosomal DNA genes, which are universally conserved within the fungal kingdom, were capable of amplifying DNA from 43 strains representing 20 species (12 genera) of medically important fungi. Sequence analysis of the products obtained from Aspergillus fumigatus, Candida albicans and Cryptococcus neoformans allowed us to design species-specific primers which only amplified homologous DNA. The use of these two PCRs in tandem allows the detection (universal PCR) and identification (species-specific PCR) of a fungal pathogen within 8 h from simulated clinical specimens.

Base Sequence↗
PubMedDate not supplied

Purification and characterization of a 93 kDa Aspergillus fumigatus antigen with diagnostic potential.

A glycoprotein with an apparent molecular weight of 93 kDa was purified from a water-soluble extract of Aspergillus fumigatus NCPF 2109 by single step affinity chromatography using the mannose-specific snowdrop (Galanthus nivalis) lectin coupled to agarose. The carbohydrate moiety contained only mannose and galactose. Partial sequencing of cyanogen bromide fragments of the antigen yielded two sequences, KQNKP and GEIPMKF?PQL, with no homology to any reported proteins. In a preliminary evaluation of its diagnostic potential the 93 kDa antigen was recognized by the sera of four patients with allergic bronchopulmonary aspergillosis, in addition to a monoclonal antibody raised against a partially purified fraction of the A. fumigatus water-soluble extract.

Amino Acid Sequence↗