The Diagnostic Laboratory Hub: A New Health Care System Reveals the Incidence and Mortality of Tuberculosis, Histoplasmosis, and Cryptococcosis of PWH in Guatemala

Background

A Diagnostic Laboratory Hub (DLH) was set up in Guatemala to provide opportunistic infection (OI) diagnosis for people with HIV (PWH).

Methods

Patients newly presenting for HIV, PWH not receiving antiretrovirals (ARVs) for >90 days but returned to care (Return/Restart), and PWH on ARVs with symptoms of OIs (ARV treatment) were prospectively included. Screening for tuberculosis, nontuberculous mycobacteria (NTM), histoplasmosis, and cryptococcosis was done. Samples were couriered to the DLH, and results were transmitted electronically. Demographic, diagnostic results, disease burden, treatment, and follow-up to 180 days were analyzed.

Results

In 2017, 1953 patients were included, 923 new HIV infections (an estimated 44% of all new HIV infections in Guatemala), 701 on ARV treatment, and 315 Return/Restart. Three hundred seventeen (16.2%) had an OI: 35.9% tuberculosis, 31.2% histoplasmosis, 18.6% cryptococcosis, 4.4% NTM, and 9.8% coinfections. Histoplasmosis was the most frequent AIDS-defining illness; 51.2% of new patients had <200 CD4 cells/mm³ with a 29.4% OI incidence; 14.3% of OIs in new HIV infections occurred with CD4 counts of 200-350 cells/mm³. OIs were the main risk factor for premature death for new HIV infections. At 180 days, patients with OIs and advanced HIV had 73-fold greater risk of death than those without advanced disease who were OI-free.

Conclusions

The DLH OI screening approach provides adequate diagnostic services and obtains relevant data. We propose a CD4 screening threshold of <350 cells/mm³. Mortality remains high, and improved interventions are required, including expansion of the DLH and access to antifungal drugs, especially liposomal amphotericin B and flucytosine.

Development and validation of a fast HPLC/photodiode array detection method for the measurement of voriconazole in human serum samples. A reference laboratory experience

The aim of this study was the development and validation of a fast and simple high performance liquid chromatography method for measuring voriconazole in human serum using ravuconazole as an external standard. The experience of the reference laboratory in therapeutic drug monitoring of voriconazole is also reported. This method is based on the precipitation of proteins in human serum and detection by HPLC/UV. Chromatographic separation is achieved using an isocratic solvent delivery with detection at 255 nm and a run time of 7 min. The assay was validated according to international guidelines and was also applied to the analysis of 141 trough serum samples from patients treated with voriconazole. All validation parameters met the criteria set out in FDA guidelines for bioanalytical methods. A high interpatient and intrapatient variability was observed in clinical samples. This method is accurate enough to perform therapeutic drug monitoring in patients receiving voriconazole treatment.

Voriconazole serum levels measured by high-performance liquid chromatography: a monocentric study in treated patients

In this study we present the results of a therapeutic drug monitoring retrospective analysis involving 14 patients with several underlying diseases who were receiving voriconazole for the treatment of fungal infections. A simple high performance liquid chromatography assay with ultraviolet detection was used in the drug monitoring. We report here that serum concentrations were highly variable and unpredictable in most patients. We also found that lack of response was more frequent in patients with levels persistently lower than 1 mg/l. The number of samples with voriconazole concentrations below 1 mg/l was significantly higher in patients who exhibited therapeutic failures (88% versus 27%; P < 0.001). In addition, the period of time in which voriconazole concentrations were maintained below 1 mg/l was slightly higher in patients in the failure group. We suggest that serum concentration should be individually quantified for patients receiving voriconazole therapy. Further prospective studies are needed to clarify the potential benefit of the individualization of treatment.

Predictors of candidaemia caused by non-albicans Candida species: results of a population-based surveillance in Barcelona, Spain

Although Candida albicans (CA) is the most common cause of Candida bloodstream infections (BSIs), recent studies have observed an increasing percentage of candidaemias caused by non-albicans Candida species (NAC). In the present study, we attempted to identify the predictors of candidaemia due to NAC compared to CA. We analyzed data from an active population-based surveillance in Barcelona (Spain) from January 2002 to December 2003. Factors associated with NAC fungaemia were determined by multivariate analysis. A total of 339 episodes of Candida BSI, in 336 patients (median age 63 years, interquartile range: 41-72 years), were included. CA was the most commonly isolated (52%), followed by Candida parapsilosis (23%), Candida tropicalis (10%), Candida glabrata (8.6%), Candida krusei (3.4%) and other NAC spp. (3%).Overall, 48% of cases were due to NAC spp. Multivariate logistic regression analysis identified factors associated with a risk of BSI due to NAC spp.: having received a haematologic transplant (OR 10.8; 95% CI 1.31-90.01; p 0.027), previous fluconazole exposure (OR 4.47; 95% CI 2.12-9.43; p <0.001) and neonatal age (OR 4.42; 95% CI 1.63-12.04; p 0.004). Conversely, previous CA colonization (OR 0.33; 95% CI 0.19-0.57; p 0.001) and previous antibiotic use (OR 0.42; 95% CI 0.21-0.85; p 0.017) were associated with CA fungaemia compared to NAC. In conclusion, NAC candidaemia comprised 48% of cases in our series. Predictors of NAC include having received a haematologic transplant, neonatal age and previous fluconazole use.

Histoplasmosis and paracoccidioidomycosis in a non-endemic area: a review of cases and diagnosis

BACKGROUND

Histoplasmosis and paracoccidioidomycosis (PCM) have increased in Spain in recent years, due firstly to the migration from endemic regions and secondly to travelers returning from these regions. In non-endemic areas, diagnosis of both diseases is hampered by the lack of experience, long silent periods, and the resemblance to other diseases such as tuberculosis and sarcoidosis.

METHODS

A total of 39 cases of imported histoplasmosis and 6 cases of PCM diagnosed in the Spanish Mycology Reference Laboratory since 2006 were analyzed. Microbiological diagnosis was performed using classical methods and also a specific real-time polymerase chain reaction (RT-PCR) assay for each microorganism.

RESULTS

We had 9 cases of probable histoplasmosis in travelers and 30 cases in immigrants, 29 of whom were defined as proven. Paracoccidioidomycosis (PCM) cases were either immigrants or people who had lived for a long period of time in endemic regions, all of whom were classified as proven cases. Cultures showed a good sensitivity in detecting Histoplasma capsulatum in immigrants with proven histoplasmosis (73%); however, growth was very slow. The fungus was never recovered in traveler patients. Paracoccidioides brasiliensis was isolated in a culture only in one case of the proven PCM. Serological methods were not very reliable in immunocompromised patients with histoplasmosis (40%). A PCR-based technique for histoplasmosis detected 55.5% of the cases in travelers (probable cases) and 89% of the cases in immigrants (proven). The PCR method for PCM detected 100% of the cases.

CONCLUSIONS

These kinds of mycoses are increasingly frequent in non-endemic areas, and newer and faster techniques should be used to reach an early diagnosis. The RT-PCR techniques developed appear to be sensitive, specific, and fast and could be helpful to detect those mycoses. However, it is also essential that physicians perform differential diagnosis in individuals coming from endemic areas.

Cutaneous infection by Phomopsis longicolla in a renal transplant recipient from Guinea: first report of human infection by this fungus

We report the case of a 72-year-old female renal transplant recipient with a nodular lesion in the distal phalange of the third left finger produced by a dematiaceous fungus that was identified as Phomopsis longicolla. She was treated with itraconazole and terbinafine and later with voriconazole, without response. The patient underwent a surgical resection with lesion-free edge and continued on voriconazole. One year later she was asymptomatic and had not developed new lesions.

Evaluation by data mining techniques of fluconazole breakpoints established by the Clinical and Laboratory Standards Institute (CLSI) and comparison with those of the European Committee on Antimicrobial Susceptibility Testing (EUCAST)

The EUCAST and the CLSI have established different breakpoints for fluconazole and Candida spp. However, the reference methodologies employed to obtain the MICs provide similar results. The aim of this work was to apply supervised classification algorithms to analyze the clinical data used by the CLSI to establish fluconazole breakpoints for Candida infections and to compare these data with the results obtained with the data set used to set up EUCAST fluconazole breakpoints, where the MIC for detecting failures was >4 mg/liter, with a sensitivity of 87%, a false-positive rate of 8%, and an area under the receiver operating characteristic (ROC) curve of 0.89. Five supervised classifiers (J48 and CART decision trees, the OneR decision rule, the naïve Bayes classifier, and simple logistic regression) were used to analyze the original cohort of patients (Rex's data set), which was used to establish CLSI breakpoints, and a later cohort of candidemia (Clancy's data set), with which CLSI breakpoints were validated. The target variable was the outcome of the infections, and the predictor variable was the MIC or dose/MIC ratio. For Rex's data set, the MIC detecting failures was >8 mg/liter, and for Clancy's data set, the MIC detecting failures was >4 mg/liter, in close agreement with the EUCAST breakpoint (MIC > 4 mg/liter). The sensitivities, false-positive rates, and areas under the ROC curve obtained by means of CART, the algorithm with the best statistical results, were 52%, 18%, and 0.7, respectively, for Rex's data set and 65%, 6%, and 0.72, respectively, for Clancy's data set. In addition, the correlation between outcome and dose/MIC ratio was analyzed for Clancy's data set, where a dose/MIC ratio of >75 was associated with successes, with a sensitivity of 93%, a false-positive rate of 29%, and an area under the ROC curve of 0.83. This dose/MIC ratio of >75 was identical to that found for the cohorts used by EUCAST to establish their breakpoints (a dose/MIC ratio of >75, with a sensitivity of 91%, a false-positive rate of 10%, and an area under the ROC curve of 0.90).

Data mining validation of fluconazole breakpoints established by the European Committee on Antimicrobial Susceptibility Testing

European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints classify Candida strains with a fluconazole MIC < or = 2 mg/liter as susceptible, those with a fluconazole MIC of 4 mg/liter as representing intermediate susceptibility, and those with a fluconazole MIC > 4 mg/liter as resistant. Machine learning models are supported by complex statistical analyses assessing whether the results have statistical relevance. The aim of this work was to use supervised classification algorithms to analyze the clinical data used to produce EUCAST fluconazole breakpoints. Five supervised classifiers (J48, Correlation and Regression Trees [CART], OneR, Naïve Bayes, and Simple Logistic) were used to analyze two cohorts of patients with oropharyngeal candidosis and candidemia. The target variable was the outcome of the infections, and the predictor variables consisted of values for the MIC or the proportion between the dose administered and the MIC of the isolate (dose/MIC). Statistical power was assessed by determining values for sensitivity and specificity, the false-positive rate, the area under the receiver operating characteristic (ROC) curve, and the Matthews correlation coefficient (MCC). CART obtained the best statistical power for a MIC > 4 mg/liter for detecting failures (sensitivity, 87%; false-positive rate, 8%; area under the ROC curve, 0.89; MCC index, 0.80). For dose/MIC determinations, the target was >75, with a sensitivity of 91%, a false-positive rate of 10%, an area under the ROC curve of 0.90, and an MCC index of 0.80. Other classifiers gave similar breakpoints with lower statistical power. EUCAST fluconazole breakpoints have been validated by means of machine learning methods. These computer tools must be incorporated in the process for developing breakpoints to avoid researcher bias, thus enhancing the statistical power of the model.

[Regional laboratory network for surveillance of invasive fungal infections and antifungal susceptibility in Latin America]

This article describes the general objectives of the Regional Laboratory Network for Surveillance of Invasive Fungal Infections and Antifungal Susceptibility in Latin America. Formation of the Network was coordinated by the Essential Medicines, Vaccines, and Health Technologies Unit of the Pan American Health Organization, with the technical and financial support of the National Center for Microbiology of the Carlos III Health Institute (Spain), and the technical support of the Microbiology Department of the Dr. C. Malbrán National Institute on Infectious Diseases (Argentina) and the Microbiology Unit of the Parasitology Service of the Adolfo Lutz Institute (Brazil). The Network's principle objectives are epidemiological surveillance of invasive fungal infections through detection of antifungal resistance and identification of emergent, invasive fungal infections; establishment of norms and common protocols for early diagnosis of mycoses; and strengthening coordination, communications, and transference mechanisms among countries. The Network must be gradually implemented and must include staff training, a systematic process for sharing technology, evaluation of diagnostic techniques, identification of fungal species, and standardized tests for antifungal susceptibility.

Correlation of the MIC and dose/MIC ratio of fluconazole to the therapeutic response of patients with mucosal candidiasis and candidemia

We report on the correlation of the outcomes for two cohorts of patients who had been treated for candidemia (126 episodes) or oropharyngeal candidiasis (110 episodes) with various doses of fluconazole and the MIC of fluconazole obtained by using the EUCAST standard for fermentative yeasts. Of 145 episodes caused by an isolate with a fluconazole MIC < or =2 mg/liter, 93.7% (136 of 145) responded to fluconazole treatment. The response for those infected with a strain with a MIC of 4 mg/liter was 66% but reached 100% when the dose was greater than 100 mg/day, whereas the response for those infected with strains with MICs > or =8 mg/liter was only 12%. Hence, a MIC of 2 mg/liter or 4 mg/liter was able to predict successful treatment. A cure rate of 93.9% (140 of 149) was achieved when the dose/MIC ratio was > or =100 but fell to 14.6% (16 of 109) when the ratio was less. The dose/MIC required to achieve a response rate of 50% (the 50% effective concentration) was 43.7 for the cohort of patients with oropharyngeal candidiasis. Classification and regression analysis indicated that a dose/MIC of 35.5 was the threshold for the prediction of cure or failure. However, an increase in exposure above this threshold further increased the probability of cure, and all patients were cured when the dose/MIC exceeded 100. Monte Carlo simulations showed a probability of target attainment of 99% at MICs < or =2 mg/liter and a pharmacodynamic target of a dose/MIC ratio of 100, which was equivalent to an unbound fraction of the fluconazole area under the curve versus the MIC of 79.

A new Aspergillus fumigatus resistance mechanism conferring in vitro cross-resistance to azole antifungals involves a combination of cyp51A alterations

Fourteen Aspergillus fumigatus clinical isolates that exhibited a pattern of reduced susceptibility to triazole drugs were analyzed. The sequences of the cyp51A gene from all isolates showed the presence of a point mutation at t364a, which led to the substitution of leucine 98 for histidine (L98H), together with the presence of two copies of a 34-bp sequence in tandem in the promoter of the cyp51A gene. Quantitative expression analysis (real-time PCR) showed up to an eightfold increase in the level of expression of the cyp51A gene compared to that by the susceptible strain. Three PCR fragments of one azole-resistant strain (strain CM2627) that included the promoter with the tandem repeat and part of cyp51A with the t364a mutation or PCR fragments with only one of the modifications were used to replace the cyp51A gene of an azole drug-susceptible A. fumigatus wild-type strain (strain CM237). Only transformants which had incorporated the tandem repeat in the promoter of the cyp51A gene and the L98H amino acid substitution exhibited similarly reduced patterns of susceptibility to all triazole agents and similarly increased levels of cyp51A expression, confirming that the combination of both alterations was responsible for the azole-resistant phenotype.

Detection of imported histoplasmosis in serum of HIV-infected patients using a real-time PCR-based assay

A new real-time PCR-based assay was used for detecting DNA of Histoplasma capsulatum in serum samples collected from four HIV-infected patients with proven histoplasmosis. The assay targeted the ITS1 region of rDNA and its in vitro sensitivity, specificity and reproducibility were evaluated. The technique detected DNA of H. capsulatum in all of the HIV-infected patients with proven histoplasmosis (4/4, 100%). The PCR result was positive for seven of the ten (70%) samples studied. The assay's specificity was determined to be 100%, since the method was negative for 25 other serum samples (10 from patients with proven aspergillosis and 15 from healthy controls). The PCR assay is a new and promising diagnostic alternative and further investigation is warranted.

New resistance mechanisms to azole drugs in Aspergillus fumigatus and emergence of antifungal drugs-resistant A. fumigatus atypical strains

Azole drug resistance in Aspergillus fumigatus is an uncommon but well-known phenomenon. The analysis of resistance mechanisms at molecular level has identified the bases for A. fumigatus azole resistance. To date, the most prevalent mechanism of azole resistance appears to be the modification of Cyp51, specifically mutations in cyp51A gene. These mutations have been associated with three different antifungal susceptibility profiles: (i) cross-resistance to itraconazole and posaconazole that has been associated with amino acid substitutions at glycine 54 (G54), (ii) elevated MICs to all azole drugs associated with amino acid substitutions at methionine M220, and (iii) cross-resistance to all azole drugs related to the presence of Cyp51A substitutions at leucine 98 for histidine (L98H) linked to a duplication in tandem of a 34 bp repeat in the cyp51A promoter region, which seem to be responsible for increased cyp51A gene expression. Another matter of concern is the increasing reports of isolation of genetic variants of A. fumigatus, originally misidentified as poorly sporulating strains of A. fumigauts, as a causative agents of invasive infection. Many of these isolates belonging to the Aspergillus section Fumigati have been found to be resistant in vitro to multiple antifungal drugs. Current data show that susceptibility profile of these variants could be predictable depending on the species. Resistance among clinical strains of filamentous fungi may become more common in the future associated with the spread of prophylaxis, pre-emptive treatments and specific therapies with antifungal agents.

Outbreak of gastric mucormycosis associated with the use of wooden tongue depressors in critically ill patients

OBJECTIVE

To describe a nosocomial outbreak of gastric mucormycosis caused by Rhizopus microsporus var. rhizopodiformis in five adult patients admitted to an intensive care unit (ICU).

DESIGN

Epidemiological surveillance study.

SETTING

A 12-bed polyvalent ICU of an acute care teaching hospital in Pamplona, Spain.

PATIENTS

Five patients admitted to the ICU requiring artificial ventilation, diagnosis on admission severe pneumonia in four patients and one polytrauma patient, within a 14-week period, were diagnosed with gastric mucormycosis based on microbiological and/or histopathological characteristics. Upper gastrointestinal bleeding was the presenting manifestation in 80% of patients.

INTERVENTIONS

Filamentous fungi isolated at the microbiology laboratory of the hospital were examined at the national Mycology Reference Laboratory in Madrid.

MEASUREMENTS AND RESULTS

Rhizopus microsporus var. rhizopodiformis growth was detected in gastric aspiration samples, environmental samples, wooden tongue depressors used to prepare oral medications (and given to patients through a nasogastric catheter), and in some tongue depressors stored in unopened boxes unexposed to the ICU environment. All depressors were purchased from the same supplier. R. microsporus was not isolated from batches purchased at different times from the same supplier and from another supplier. The outbreak terminated when contaminated tongue depressors were withdrawn from use.

CONCLUSIONS

Wooden tongue depressors contaminated by R. microsporus var. rhizopodiformis used to prepare oral medications caused an outbreak of fungal gastritis with an attributable mortality of 40%. Wooden material should not be used in the hospital setting.

Molecular typing of clinical and environmental isolates of Scedosporium prolificans by inter-simple-sequence-repeat polymerase chain reaction

Invasive infections by Scedosporium prolificans have increased alarmingly in recent years, mainly in immunosuppressed patients. The epidemiology, pathogenesis and the natural habitat of this pathogen are practically unknown. Isolates of S. prolificans were distinguished from one another by inter-simple-sequence-repeat (ISSR) fingerprinting, a technique based on the high degree of polymorphism of the multisatellite genetic markers used. This technique was found useful for typing 84 isolates of S. prolificans from different countries and sources. The assemblage of S. prolificans isolates tested was extremely diverse, with 35 genotypes present. Several patients were found to have been infected or colonized by more than one strain. Overall, this technique facilitates the epidemiological study of S. prolificans infection.

Multicenter evaluation of the reproducibility of the proposed antifungal susceptibility testing method for fermentative yeasts of the Antifungal Susceptibility Testing Subcommittee of the European Committee on Antimicrobial Susceptibility Testing (AFST-EUCAST)

OBJECTIVE

To evaluate the intra- and inter-laboratory reproducibility of a new standard for susceptibility testing of fermentative yeasts. This standard is based on the M27-A procedure of the National Committee for Clinical Laboratory Standards (NCCLS), but incorporates several modifications, including spectrophotometric growth-dependent endpoint reading.

METHODS

Nine laboratories participated in the study. Common material lots were used to test six Candida species (one each of C. albicans, C. tropicalis, C. parapsilosis, C. glabrata, C. krusei, and C. lusitaniae), and two quality control strains (C. krusei ATCC6258 and C. parapsilosis ATCC22019). Triplicate testing on three separate days was performed in microtiter format with RPMI-2% glucose, pH 7.0. Flucytosine, fluconazole and itraconazole were tested. In total, 3888 MIC values were included in the analyses. Reproducibility was calculated by means of agreement (percentage of MICs within one two-fold dilution of the mode) and intraclass correlation coefficient (ICC, maximum value of 1).

RESULTS

The average intra-laboratory agreements were 99% and 96% after 24 h and 48 h of incubation, respectively, with ICCs of 0.98 and 0.97 (P < 0.05). Two strains exhibiting a trailing effect showed intra-laboratory agreement of 92% and ICCs of < 0.91 at 48 h. The inter-laboratory agreement was 94% and 88% after 24 h and 48 h, respectively, with ICCs of 0.93 and 0.91 (P < 0.05). Lower values of agreement and ICCs were obtained for strains exhibiting trailing after 48 h of incubation. Itraconazole yielded the lowest values of reproducibility.

CONCLUSION

The new procedure of EUCAST for antifungal susceptibility testing is a reproducible method within and between laboratories and offers several advantages over the NCCLS approved method.

In vitro evaluation of combination of terbinafine with itraconazole or amphotericin B against Zygomycota

The combined activity in vitro of amphotericin B/terbinafine and itraconazole/terbinafine was assessed against 17 clinical isolates of Zygomycota using a checkerboard technique. Itraconazole/terbinafine combination exhibited a potent synergistic effect against the most of strains. Amphotericin B/terbinafine combination showed an indifferent interaction for Rhizopus oryzae, and an additive effect for the other species.

Transient fungemia caused by an amphotericin B-resistant isolate of Candida haemulonii

A bloodstream infection due to Candida haemulonii afflicting a patient with fever and a medical history of megaloblastic anemia is reported. The clinical isolate was misidentified by the API 20C and VITEK identification systems. The results of susceptibility tests showed that the MIC of amphotericin B for C. haemulonii was 4 microg/ml. Additional susceptibility testing procedures based on the use of antibiotic medium 3 and Iso-Sensitest broth were performed, and killing curves were determined. Two collection strains of C. haemulonii were employed as controls. The three isolates exhibited resistance to amphotericin B in vitro regardless of the antifungal susceptibility testing method employed. In addition, the MICs of fluconazole for the three isolates were high. Further studies are needed in order to ascertain whether this species exhibits innate or acquired resistance to amphotericin B and other antifungal agents.

[Systemic yeast infections in a general hospital. Correlation between study of susceptibility in vitro and patient survival to the fungal infection episode]

BACKGROUND

Fungi are important causal agents of nosocomial infections, that usually have high mortality rates.

AIM

To evaluate the species distribution and susceptibility patterns of deep yeast infections in a General Hospital and to correlate those results with patient survival.

MATERIAL AND METHODS

Twenty one strains (from five pediatric and 16 from adult patients) were studied. Antifungal Susceptibility Testing (AST) to Amphotericin B (Anfb), Fluorocytosine (5FC), Fluconazole (FZ) and Itraconazole (IZ) was performed according to the EUCAST document. Clinical data of patients was obtained and survival to the infection was recorded.

RESULTS

C. albicans was isolated in 11 samples (52%), C. parapsilosis in three samples (14%), C. glabrata in two samples (9%), C. tropicalis in one sample (5%) and C. neoformans in four samples (19%). Twenty three percent of fungi were recovered at the Surgical Intensive Care Unit. The MICs ranged between 0.25 and 0.5 microgram/mL for Anfb; between 0.25 and 16 micrograms/ml for SFC, between 0.12 and 32 micrograms/mL for FZ and 0.015 and 0.5 microgram/mL for IZ. No association between antifungal susceptibility and patient survival was observed.

CONCLUSIONS

C. albicans continues to be the most frequently isolated yeast, however, non-albicans species are an emergent group causing nosocomial infections. Surgical procedures are the main source of fungal infections in this sample.

Present status of the detection of antifungal resistance: the perspective from both sides of the ocean

The NCCLS reference methodology for antifungal susceptibility testing is a new milestone of the evolution of medical mycology. The use of this methodology however, is not problem-free. At present, major limitations are a trailing phenomenon with azoles, unreliable detection of resistance to amphotericin B, poor growth of some organisms and unpractical procedures for the clinical laboratory. Herein a overview of NCCLS guidelines for yeasts and filamentous fungi is presented. Likewise, a review of studies conducted trying to overcome the limitations of reference procedures is also included. Several alternative approaches are reviewed as alternative media, inoculum size and incubation time. Modifications of reading procedure and endpoint determination are also evaluated. Agar diffusion methods and other methods for susceptibility testing are cited. Finally, we discuss the data on correlation of the in vitro results with the in vivo activity.

Azasordarins: susceptibility of fluconazole-susceptible and fluconazole-resistant clinical isolates of Candida spp. to GW 471558

The in vitro activity of the azasordarin GW 471558 was compared with those of amphotericin B, flucytosine, itraconazole, and ketoconazole against 177 clinical isolates of Candida spp. GW 471558 showed potent activity against Candida albicans, Candida glabrata, and Candida tropicalis, even against isolates with decreased susceptibility to azoles. Candida krusei, Candida parapsilosis, Candida lusitaniae, and Candida guilliermondii are resistant to GW 471558 in vitro (MICs, >128 microg/ml).