Source of infection in candida endophthalmitis in drug addicts

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Candidosis of the genital tract in non-pregnant women

Of 300 non-pregnant women seen in an STD clinic, 94 (31.3%) harboured C. albicans or C. glabrata in the genital tract; 84 of these women (89.4%) had at least one moderate or marked symptom or clinical sign. Of the 94 women with Candida, 50 had another genital infection; 38% of these 50 women had at least one moderate or marked symptom or clinical sign, compared with 75% of the 44 women with no other infection. This difference is significant. Of the 146 women taking oral contraceptives, 51 (34.9%) had Candida, compared with 43 (27.9%) of the 154 women who were not. The incidence of trichomoniasis, anaerobic vaginitis and non-specific genital infection was lower among women with Candida than among the others.

Antibody to Aspergillus fumigatus antigens in normal sera: influence on positive-negative discrimination in ELISA

The response of precipitin-negative sera from non-selected asthmatic patients against a range of somatic and culture filtrate antigens of Aspergillus fumigatus in ELISA for anti-A. fumigatus IgG is described. Antibody to the various antigens was widely distributed but the precise distribution was dependent upon antigen type. To determine how the selection of negative reference sera from precipitin-negative sera can influence the discrimination between precipitin-positive and -negative sera in ELISA, panels of 10 sera were chosen from the extremes of the frequency distribution and by random selection. The closest agreement between precipitin testing and ELISA was seen when randomly-selected negative reference sera were incorporated in the assay, although the degree of correlation was dependent upon the detector antigen. These findings demonstrate the requirement for careful selection of sera included as negative reference sera in ELISA for anti-A. fumigatus IgG.

In-vitro resistance to imidazole antifungals in Candida albicans

Three strains of Candida albicans from patients with chronic mucocutaneous candidosis (CMC) who relapsed during prolonged treatment with ketoconazole were compared with three other Can. albicans strains by means of an agar incorporation MIC method, a broth microdilution method for IC30 determination, and a hyphal elongation assessment method. The MICs of ketoconazole, tioconazole and miconazole were difficult to interpret, but were much higher for the three CMC strains if low inoculum concentrations and short incubation times were used. The IC30S of the three imidazoles were much higher for the CMC strains than for the others. The imidazoles all caused minimal inhibition of hyphal elongation by the three CMC strains at concentrations up to 50 mg/l. Concentrations of 0.5 mg/l caused marked inhibition of the other strains.

Rapid enzyme-linked immunosorbent assay (ELISA) for the detection of IgG antibodies against Micropolyspora faeni and Thermoactinomyces vulgaris

A rapid ELISA was developed for the detection of specific IgG against Micropolyspora faeni and Thermoactinomyces vulgaris and compared with counterimmunoelectrophoresis (CIE) in twenty-seven patients with suspected farmer's lung disease (FLD). Seventeen patients had precipitins to M. faeni or T. vulgaris or both, and ten had no precipitins. The optimum conditions for each step in the ELISA were determined: pre-equilibration of reagents at 37 C and vigorous agitation during incubation enabled the total test time required for the procedure to be reduced to 4 hr. A serum dilution of 10-fold produced good differentiation between CIE-positive and -negative sera. Little correlation was seen between CIE and ELISA for either M. faeni or T. vulgaris antigens in tests with sera from patients with precipitins: high readings were often recorded in ELISA where no precipitins had been detected with the same antigen. Positive-negative discrimination of unknown sera in ELISA was achieved through the inclusion of CIE-positive and -negative reference sera in each test run. Thirteen CIE-positive sera were classed as positive in ELISA with the M. faeni antigen while eight of thirteen CIE-positive sera were positive in ELISA with the T. vulgaris antigen. For both antigens, four CIE-negative sera were recorded as positive in ELISA.

Antigen and antibody attachment in ELISA for Aspergillus fumigatus IgG antibodies

Four commercial antigen extracts of Aspergillus fumigatus were evaluated for use in a rapid enzyme-linked immunosorbent assay (ELISA) for anti-A. fumigatus IgG. Initial binding of both somatic and culture filtrate preparations to a polyvinyl chloride solid phase was concentration dependent and increased with incubation time. Antigen binding to the solid phase was reproducible. Binding of A. fumigatus precipitin-positive serum to bound antigen was rapid. All four A. fumigatus antigens demonstrated similar dose-response curves when tested against pooled sera containing a high titre of A. fumigatus antibodies. Detectable activity in precipitin test-negative sera decreased rapidly with dilution. All the antigen preparations were found to be suitable for ELISA procedures and permit the rapid determination of IgG antibodies to A. fumigatus.

Influence of food on the pharmacokinetics of ketoconazole

Eight healthy adults were given single oral doses of ketoconazole (200, 400, 600, and 800 mg) in the fasting state and with a standard breakfast at weekly intervals according to a balanced block design. Concentrations in serum were measured up to 32 h after the dose. Food did not reduce ketoconazole absorption or significantly alter peak ketoconazole concentrations in serum, though there was a food-related delay in achieving peak concentrations. At the 400- and 600-mg doses, food appeared to enhance absorption, but this effect was not seen at the 800-mg dose. With an increase in dose, the half-life and area under the serum concentration-time curve increased disproportionately, suggesting that the pharmacokinetics of ketoconazole may be dose dependent. Up to the 800-mg dose, the elimination of ketoconazole did not appear to be saturable. Administration of the drug with food is unlikely to be a cause of therapeutic failure.

Evaluation of an enzyme-linked immunosorbent assay (ELISA) for the diagnosis of Aspergillus fumigatus intranasal infection of the dog

ELISA appears to be a less reliable method than counterimmunoelectrophoresis for the diagnosis of nasal aspergillosis in the dog. False-positive or false-negative results were recorded for anti-A. fumigatus IgG in nine animals with aspergillosis and in 27 disease-free dogs although this problem could be reduced with careful selection of antigen.

Evaluation of a rapid enzyme-linked immunosorbent assay for IgG antibodies to Aspergillus fumigatus in the serological diagnosis of allergic aspergillosis

A range of 6 somatic and culture filtrate antigens of Aspergillus fumigatus were evaluated in a rapid ELISA procedure for anti-A. fumigatus IgG where the component incubation times had been reduced to 10 min. Sera from patients with allergic aspergillosis, patients with suspected allergic aspergillosis, and asthmatic patients with or without A. fumigatus precipitins were tested. For all antigens, levels of anti-A. fumigatus IgG were higher in patients with allergic aspergillosis than in the other 3 groups. Low levels of specific IgG were, however, detected in asthmatic patients who had no precipitins against A. fumigatus. None of the antigen preparations enabled all patients with proven or suspected allergic aspergillosis to be separated from the other 2 groups of asthmatic patients. Positive-negative discrimination in ELISA was achieved by the inclusion of 10 pools of precipitin test-negative sera from the 50 asthmatics without A. fumigatus precipitins. The number of sera that were classed as positive in ELISA ranged from 9 to 15 in the allergic aspergillosis group, depending on the antigen used; in the suspected aspergillosis group, the number of positive reactions ranged from 1 to 8, while in the asthmatics with precipitins, the number ranged from 0 to 2.

Ultrastructural features of phagocytosis and intracellular killing of Candida albicans by mouse polymorphonuclear phagocyte monolayers

Phagocyte monolayers provided a simple method of following ultrastructural events associated with phagocytosis and intracellular killing of Candida albicans. Preformed monolayers of mouse polymorphonuclear (PMN) phagocytes attached to glass coverslips were incubated with blastospore phase C. albicans and then examined by scanning and transmission electron microscopy. Scanning electron microscopy revealed phagocytosis of C. albicans by mouse phagocytes. Ingestion of the organism was facilitated by the production of lamellipodia by the phagocytes. Transmission electron microscopy revealed complete phagocytosis of C. albicans and the fusion of lysosomal granules with loose and tight phagosomes. Ingested C. albicans remained structurally intact after 2 hr incubation in blastospore-free medium. However, cytoplasmic alterations were clearly evident, with a patchy loss of electron density. Alterations of the blastospore cell wall were also observed, with complete disruption of the plasma membrane but the wall remaining morphologically intact.

Effect of imidazole antifungals on the development of germ tubes by strains of Candida albicans

Three imidazole antifungals (ketoconazole, tioconazole and miconazole) were examined for their effect on germ tube development by synchronous blastospore populations and on actively growing germ tubes of three strains of Candida albicans. After incubation in serum for 4 h the largest differences in germ tube elongation between strains were detected at concentrations (0.005 mg/l) where minimal inhibition was observed. Germ tube elongation in antifungal-containing serum diminished with increasing concentration. Maximum inhibition occurred at concentrations of 0.5 mg/l. All three antifungals inhibited the rate of hyphal elongation by the strains over a 6 h period at this concentration. Tests where germinated blastospores of strain 3281 were transferred to serum containing 0.5 mg/l of antifungal indicated that all three drugs inhibited further elongation. However, the rate of inhibition was dependent upon the length of time germination had proceeded in serum alone prior to transfer to antifungal-containing serum.

Multiple dose pharmacokinetics of ketoconazole and their effects on antipyrine kinetics in man

Ketoconazole 200 mg was given twice daily for five days to eight subjects. The serum pharmacokinetics were examined with the first dose on day 1 and with the ninth dose on day 5. The serum half life of ketoconazole was 74.8 +/- 13.9 min (mean +/- S.D.) on day 1, and 155.9 +/- 32.7 min on day 5. On day 1 the area under the serum concentration time curve was 626.9 +/- 230.1 mg/l.min, and 1441 +/- 897.3 mg/l.min on day 5. Antipyrine kinetics were determined before and after the course of ketoconazole. There was no significant change in the clearance and half life of antipyrine. Ketoconazole in the doses used in this study does not appear to alter hepatic microsomal enzyme activity in man. The increased ketoconazole half life and area under the serum concentration time curve on day 5 were in part caused by food. Other mechanisms for these changes such as saturation of a tissue compartment or a change in the elimination of ketoconazole during chronic dosing, may also be responsible.

Further evaluation of factors affecting a rapid ELISA procedure for detection of IgG antibodies to Candida albicans

A rapid enzyme-linked immunosorbent assay (ELISA) was developed to detect IgG antibodies against a cytoplasmic antigen of Candida albicans. The optimum conditions and time required for each step were investigated. Pre-equilibration at 37 degrees C and constant agitation of immunoreactants resulted in a total test time of 1 h for examination of single serum dilutions. Initial binding of the antigen at 37 degrees C to the solid phase occurred within 4-6 min and was dependent on concentration. A serum dilution of 100-fold resulted in adequate discrimination between precipitin test-positive and -negative sera. Interaction of antibody and the bound antigen was maximal after 6 min incubation at 37 degrees C and was dependent upon the precipitin titre of the serum. Ten minutes was selected as the optimal incubation time for each of the stages, by which time maximal binding had occurred, irrespective of antibody affinity for antigen. The ELISA was completed by incubation at 37 degrees C for 10 min with alkaline phosphatase-conjugated anti-human IgG. Discrimination between positive and negative test sera was achieved by incorporating in each test run precipitin test-positive and -negative reference sera from groups of persons with or without C. albicans colonization or infection. Closest agreement between sera positive for C. albicans precipitins by counter-immunoelectrophoresis and the rapid ELISA was seen when reference negative sera were selected from non-colonized individuals.

Computer-assisted rapid enzyme-linked immunosorbent assay (ELISA) in the serological diagnosis of aspergillosis

A computer-assisted method for the positive/negative discrimination of ELISA data is described. This method was applied to a rapid ELISA procedure for IgG class antibodies to Aspergillus fumigatus in which the performance time of the test was reduced to 1 h. The method gives results which compare well with those by agar gel double diffusion (AGDD). The computer-assisted reading, calculation and tabulation of ELISA results from one microtitre plate is performed in less than 2 min and permits analysis of large numbers of specimens.

Rapid enzyme-linked immunosorbent assay (ELISA) for Aspergillus fumigatus antibodies

A rapid enzyme-linked immunosorbent assay (ELISA) where component incubation periods were shortened to one hour, was compared with agar gel double diffusion (AGDD) and a standard ELISA procedure for detecting antibodies to Aspergillus fumigatus in 28 asthmatic patients with suspected allergic aspergillosis. Using two A fumigatus antigens the rapid ELISA compared well with AGDD and the standard ELISA method. Eleven sera that reacted with both antigens in AGDD were all positive against antigen 1 in both forms of ELISA, but two failed to react with antigen 2 in the standard ELISA and three failed to react with this antigen in the rapid method. Thirteen AGDD-negative sera were also negative in both forms of ELISA. The rapid ELISA provides a sensitive and reproducible test for routine serological investigation of allergic aspergillosis.

Rapid serological diagnosis of Aspergillus fumigatus infection of the frontal sinuses and nasal chambers of the dog

Aspergillus fumigatus precipitins in dog sera were detected by counterimmunoelectrophoresis (CIE). The procedure gave results within 90 minutes compared with 72 to 96 hours required in agar-gel double diffusion. Culture-filtrate antigens from two-week-old cultures of A fumigatus and two-day-old mycelial antigens produced the strongest reactions in CIE tests and the former antigen also revealed high titres in tests with serum from seven of 14 dogs with A fumigatus precipitins. Serum from these 14 dogs also reacted in CIE tests with a number of Penicillium species antigens.

Differentiation of extracellular from ingested Candida albicans blastospores in phagocytosis tests by staining with fluorescein-labelled concanavalin A

In phagocytosis tests with human polymorphonuclear (PMN) cells, extracellular blastospores of Candida albicans could be distinguished microscopically from ingested blastospores mor easily than with methods used previously by staining phagocyte monolayers with fluorescent-labelled concanavalin A. This stain reacted with the cell wall mannan of extracellular blastospores but seemed unable to reach that of the ingested blastospores. This technique both improves determination of phagocytic indices and checks that extracellular blastospores have been washed away before assessment of intracellular survival and growth.

Production of germ tubes by virulent and attenuated strains of Candida albicans

Two strains (no. 19321 and no. 19273) of Candida albicans that were obtained from patients with vaginal thrush and were virulent for mice formed germ tubes after incubation in fresh mouse serum and mouse kidney extract more rapidly and to a greater extent than did two strains (no. 22114 and no. 21462) that were isolated from patients with transient candidemia and were attenuated for mice. After incubation in fresh human serum, the strain differences in germination were not as marked although the pattern was similar. Synchronous cultures of strains no. 19321 and no. 22114 showed differences similar to those shown by asynchronous cultures in the mouse and human sera and in the mouse kidney extract. The viability of the strains was maintained in all three types of media; thus, nonspecific humoral defense mechanisms had little effect on the attenuated strain.

Resistance of virulent and attenuated strains of Candida albicans to intracellular killing by human and mouse phagocytes

Blastospores of two strains (no. 19321 and no. 19273) of Candida albicans that were obtained from patients with vaginal thrush and were virulent for mice showed no significant difference in degree of resistance to phagocytosis by human and mouse phagocytes (mostly polymorphonuclear) compared with blastospores of two strains (no. 22114 and no. 21462) that were isolated from patients with transient candidemia and were attenuated for mice. In contrast, more blastospores of the virulent strains survived intracellularly than did those of the attenuated strains over a 2-hr period, after which the surviving blastospores began to form germ tubes. Heterogeneity in the populations of blastospores was suggested, because progeny from surviving blastospores of attenuated strain no. 22114 behaved similarly to virulent strains in tests with human and mouse phagocytes and in virulence tests in mice.

Sero-diagnosis of invasive aspergillosis: attempts to determine antigen and antibody relevance to infection

Attempt was made to define antigens and antisera which might prove useful in diagnosis of invasive aspergillosis in man. A convalescent antiserum (serum from rabbits after liver infection with Aspergillus fumigatus conidia) which might be more representative of immunological reaction to fungal growth in vivo, did not react in enzyme-linked immunosorbent assay with commerical antigens which are used at present in attempts to detect antibody response in systemic infections in man. However, this convalescent antiserum reacted with antigens from a range of fungal extracts. Antigens from young culture filtrates in particular the 24th culture filtrate are advocated as the standard antigens for antibody detection using conventional immunoprecipitation techniques. For the detection of circulating antigens, the use of convalescent antiserum in enzyme-linked immunosorbent assay might be promising in the early diagnosis of invasive aspergillosis.

Comparison of the growth of virulent and attenuated strains of Candida albicans in the kidneys of normal and cortison-treated mice by chitin assay

Candida albicans strain 22114 was avirulent for mice compared with strain 19321 in that, administered intravenously, 10(6) blastospores of 22114 failed to kill whereas 10(6) blastospores of 19321 produced 100% mortality. Cortisone treatment rendered mice susceptible to killing by 22114. Chitin assay showed that cortisone stimulated the growth of both strains in the mouse kidney. Growth of 19321 was increased up to five-fold and 22114 up to forty-fold. The strains may have differential susceptibility to cortisone-sensitive host defences which control fungal growth in vivo.

The occurrence and treatment of false positive reactions in enzyme-linked immunosorbent assays (ELISA) for the presence of fungal antigens in clinical samples

Non-specific positive reactions have been revealed in enzyme-linked immunosorbent assays (ELISA) of sera for the presence of fungal antigen. These false positives were recognized by their occurrence in tests for both Candida albicans and Aspergillus fumigatus antigens and by their response to dithiothreitol, combined with their reaction with non-immune rabbit globulin. A scheme is proposed which differentiates between true and false positive reactions. Use of fractionated anti-fungal globulin in conjugates reduced the incidence of false positive results in sera from hospitalized patients and eliminated them from sera of healthy subjects. The test scheme was applied to two panels of sera containing samples from patients with (a) invasive candidosis and (b) invasive aspergillosis. The relevance of ELISA tests for the detection of fungal antigen in human serum is discussed.

Detection of circulating antigen of Aspergillus fumigatus in sera of mice and rabbits by enzyme-linked immunosorbent assay

Circulating antigen of Aspergillus fumigatus was demonstrated in the sera of experimentally infected, cortisone-treated mice and rabbits by enzyme-linked immunosorbent assay (micro-ELISA), confirming earlier results where fungal antigen had been detected by counter-immunoelectrophoresis (CIE). Peaks of detection of circulating antigen by CIE and micro-ELISA in mice were not simultaneous suggesting that the nature of the predominant antigens may have altered during the course of infection. CIE failed to detect fungal antigen in infected rabbits whereas micro-ELISA monitored antigenemia until death. Both CIE and micro-ELISA demonstrated the rapid clearance of intravenously inoculated Aspergillus-antigen from the rabbit circulation.

Enzyme-linked immunosorbent assay of antigens from Candida albicans circulating in infected mice and rabbits: the role of mannan

Various antisera raised either to antigens of Candida albicans or to sub-lethal infections of blastospores (convalescent sera) were tested for their efficacy in diagnosing systemic disease in artifically infected animals. Globulin from convalescent serum, when conjugated with alkaline phosphatase and used in enzyme-linked immunosorbent assays (ELISA), was the only antiserum type which detected circulating Candida-related antigen in the serum of infected animals. Conjugates made from anti-mannan, anti-blastospore or antimycelial globulin did not detect antigen. Mannan did not appear to be related to an antigen produced in sera of experimentally infected mice. The significance of these results in the diagnosis of systemic candidosis is discussed.

Diagnosis of invasive candidosis by enzyme immunoassay of serum antigen

Enzyme immunoassay was used to measure Candida albicans-related antigen in sera of rabbits and mice infected with C albicans. A range of heterologous antigens tested gave no cross reactions. Of the three patients who were investigated and gave positive reactions, two were confirmed as having deep candida infections. Enzyme immunoassay is efficient, simple, and sensitive, and may prove valuable in the early diagnosis of invasive candida infections.

Optimum conditions for initiation of filamentation in Candida albicans

A medium that initially produced filaments from almost all of its Candida albicans blastospore inoculum contained 1% mycological peptone and 0.2% glucose, final pH 7.4-7.5. The medium was inoculated to 10-6 cells/ml and incubated at 40 degrees C. Reversion to secondary blastospores began at a mean of 2.4 h after inoculation. The patterns of utilization of growth nutrients during optimal mycelial growth showed no correlation with the events of filamentation.

Relevance of antigenicity of Candida albicans growth phases to diagnosis of systemic candidiasis

The antigenicity of the two growth phases of Candida albicans has been compared by using crossed immunoelectrophoresis and double-diffusion techniques. Qualitative and quantitative differences in antigenic composition between the phases have been revealed and moreover a specific mycelial antigenic component demonstrated.It is postulated that the use of specific mycelial antigens for routine diagnostic precipitin testing in patients with suspected systemic candidiasis would give more reliable results than at present obtained with yeast cell antigens.