Histoplasmosis associated with exploring a bat-inhabited cave in Costa Rica, 1998-1999

Between October 1998 and April 1999, 51 persons belonging to two separate groups developed acute pulmonary histoplasmosis after visiting a cave in Costa Rica. The first group consisted of 61 children and 14 adults from San Jose, Costa Rica; 44 (72%) were diagnosed with acute histoplasmosis. The second group comprised 14 tourists from the United States and Canada; 9 (64%) were diagnosed with histoplasmosis. After a median incubation time of 14 days, the most common symptoms were headache, fever, cough, and myalgias. Risk factors for developing histoplasmosis included crawling (odds ratio [OR] = 17.5, 95% confidence interval [CI] = 2.3-802) and visiting one specific room (OR = 3.4, 95% CI = 1.0-12.3) in the cave. Washing hands (OR = 0.1, 95% CI = 0.01-0.6) after exiting the cave was associated with a decreased risk of developing histoplasmosis. Histoplasma capsulatum was isolated from bat guano collected from inside the cave. Persons who explore caves, whether for recreation or science, should be aware of the risk bat-inhabited caves pose for developing histoplasmosis, especially if they are immunocompromised in any way.

Incidence of bloodstream infections due to Candida species and in vitro susceptibilities of isolates collected from 1998 to 2000 in a population-based active surveillance program

To determine the incidence of Candida bloodstream infections (BSI) and antifungal drug resistance, population-based active laboratory surveillance was conducted from October 1998 through September 2000 in two areas of the United States (Baltimore, Md., and the state of Connecticut; combined population, 4.7 million). A total of 1,143 cases were detected, for an average adjusted annual incidence of 10 per 100,000 population or 1.5 per 10,000 hospital days. In 28% of patients, Candida BSI developed prior to or on the day of admission; only 36% of patients were in an intensive care unit at the time of diagnosis. No fewer than 78% of patients had a central catheter in place at the time of diagnosis, and 50% had undergone surgery within the previous 3 months. Candida albicans comprised 45% of the isolates, followed by C. glabrata (24%), C. parapsilosis (13%), and C. tropicalis (12%). Only 1.2% of C. albicans isolates were resistant to fluconazole (MIC, > or = 64 microg/ml), compared to 7% of C. glabrata isolates and 6% of C. tropicalis isolates. Only 0.9% of C. albicans isolates were resistant to itraconazole (MIC, > or = 1 micro g/ml), compared to 19.5% of C. glabrata isolates and 6% of C. tropicalis isolates. Only 4.3% of C. albicans isolates were resistant to flucytosine (MIC, > or = 32 microg/ml), compared to < 1% of C. parapsilosis and C. tropicalis isolates and no C. glabrata isolates. As determined by E-test, the MICs of amphotericin B were > or = 0.38 microg/ml for 10% of Candida isolates, > or =1 microg/ml for 1.7% of isolates, and > or = 2 microg/ml for 0.4% of isolates. Our findings highlight changes in the epidemiology of Candida BSI in the 1990s and provide a basis upon which to conduct further studies of selected high-risk subpopulations.

Drug resistance genes and trailing growth in Candida albicans isolates

OBJECTIVES

To investigate possible molecular mechanisms of azole resistance among fluconazole-susceptible bloodstream isolates of Candida albicans that displayed the trailing growth phenomenon, and to compare these isolates with bloodstream and mucosal isolates that showed reduced susceptibilities to fluconazole.

METHODS

Twelve C. albicans isolates-seven trailing and five susceptible dose dependent (SDD) or resistant (R)-were screened for ERG11 mutations by DNA sequencing and quantification of ERG11, CDR1 and MDR1 expression by RT-PCR using the LightCycler high-speed PCR system.

RESULTS

SDD and R isolates possessed more homozygous ERG11 mutations than did the trailing isolates. Two of these, V404I and V509M, have not been described previously and were found exclusively in fluconazole SDD and R isolates. Quantification of ERG11 expression revealed that both trailing and SDD and R isolates were capable of ERG11 up-regulation in response to fluconazole, although the SDD and R isolates showed maximal up-regulation at higher fluconazole concentrations. Quantification of CDR1 and MDR1 revealed that all isolates, regardless of in vitro fluconazole response, were capable of CDR1 and MDR1 up-regulation following fluconazole exposure. Furthermore, the SDD and R isolates expressed higher constitutive levels of CDR1 and MDR1 or CDR1, respectively, in the absence of drug compared with trailing isolates.

CONCLUSIONS

Trailing isolates, although susceptible to fluconazole, express the same molecular mechanisms as SDD and R isolates following fluconazole exposure but regulate them differently.

A large outbreak of histoplasmosis among American travelers associated with a hotel in Acapulco, Mexico, spring 2001

During spring 2001, college students from Pennsylvania reported an acute febrile respiratory illness after returning from spring break vacation in Acapulco, Mexico. Acute pulmonary histoplasmosis was presumptively diagnosed and the cluster of illness was reported to the Centers of Disease Control and Prevention. A large investigation then ensued, which included finding student-travelers for interviews and requesting sera for histoplasmosis testing. We defined a clinical case by fever and at least one of the following: cough, shortness of breath, chest pain, or headache, in an Acapulco traveler during March-May 2001. A laboratory-confirmed case had positive serology. An initial study determined that the likely site of histoplasmosis exposure was Hotel H; we therefore performed a large cohort study among travelers who stayed at Hotel H. Of 757 contacted, 262 (36%) met the clinical case definition. Of 273 serum specimens tested, 148 (54%) were positive. Frequent use of Hotel H's stairwells, where construction was ongoing, was associated with increased risk of illness (relative risk = 10.5, 95% confidence interval = 3.7-30.5; P < 0.001). This is the first histoplasmosis outbreak associated with a hotel undergoing construction. Hotels in endemic areas should consider construction precaution measures to prevent histoplasmosis among their guests.

Persistence of oropharyngeal Candida albicans strains with reduced susceptibilities to fluconazole among human immunodeficiency virus-seropositive children and adults in a long-term care facility

Nineteen oropharyngeal Candida albicans isolates from six children and seven adults living with AIDS at the Russia AIDS Centre, Moscow, from 1990 to 1998 were selected for molecular typing. Two fluconazole-resistant C. albicans genotypes were identified from a child who contracted human immunodeficiency virus infection during the Elista Hospital outbreak in the Kalmyk Republic in 1989. Highly related strains were observed 4 years later in the oral lesions and colonization of two patients and a health care worker. There may be a tendency for persons who are living with AIDS in a long-term care facility and who receive fluconazole therapy for oropharyngeal candidiasis to harbor and spread fluconazole-resistant C. albicans strains.

Outbreak of invasive aspergillosis among renal transplant recipients

Invasive aspergillosis (IA) is rare among renal transplant recipients (RTRs). We investigated a cluster of IA among RTRs at a California hospital from January to February 2001, when construction was ongoing. We conducted a cohort study among RTRs who were hospitalized between January 1 and February 5, 2001, to determine risk factors for IA. IA was defined using established guidelines. Four IA cases occurred among 40 RTRs hospitalized during the study period. Factors associated with an increased risk of IA included prolonged hemodialysis, lengthy corticosteroid treatment posttransplant, and use of sirolimus alone or with mycophenolate (P<0.05). After the study period, three additional RTRs developed IA; two Aspergillus isolates recovered from these patients had indistinguishable profiles by DNA fingerprinting, suggesting common-source exposure. This study suggests that immunosuppressed RTRs can be at an increased risk for IA. Measures to prevent IA in these patients should be taken during hospital construction.

Stability of allelic frequencies and distributions of Candida albicans microsatellite loci from U.S. population-based surveillance isolates

Allelic distributions and frequencies of five Candida albicans microsatellite loci have been determined for strains isolated from the bloodstream and obtained through active population-based surveillance in two U.S. metropolitan areas between 1998 and 2000. These data were compared to data for isolates obtained from two other U.S. regions in 1992 to 1993. In a majority of pairwise combinations between sites, no evidence was seen for shifts in microsatellite allelic frequencies. One to three alleles were highly predominant and correlated with major genotypes. These data both support the concepts of allelic stability and genetic equilibria and suggest that, in the United States, strains of C. albicans isolated from the bloodstream may form a defined, genetically homogeneous population across geographical distance and time.

Population-based surveillance and a case-control study of risk factors for endemic lymphocutaneous sporotrichosis in Peru

Population-based surveillance and a case-control study were conducted in Abancay, Peru, to estimate the burden of disease and to determine risk factors for sporadic lymphocutaneous sporotrichosis (LS). Laboratory records from local hospitals were reviewed for the years of 1997 and 1998, and prospective surveillance was conducted for the period of September 1998 through September 1999. A case-control study was conducted with 2 matched control subjects per case patient. The mean annual incidence was 98 cases per 100,000 persons. Children had an incidence 3 times higher than that for adults and were more likely to have LS lesions on the face and neck. Identified risk factors included owning a cat, playing in crop fields, having a dirt floor in the house, working mainly outdoors, and having a ceiling made of raw wood or conditions associated with a lower socioeconomic status. Decreased environmental exposure, such wearing protective clothing during construction activities for adults or limiting contact with cats and soil for children, and improvements in living spaces may decrease the incidence of LS.

Comparative evaluation of NCCLS M27-A and EUCAST broth microdilution procedures for antifungal susceptibility testing of candida species

A two-laboratory study was performed to evaluate the correlation between the NCCLS M27-A and EUCAST microdilution procedures for antifungal testing of Candida spp. A panel of 109 bloodstream isolates was tested against amphotericin B, flucytosine, fluconazole, and itraconazole. Overall, the agreement was 92% and the intraclass correlation coefficient was 0.90 (P < 0.05).

Fungal infections among returning travelers

Endemic mycoses, such as histoplasmosis, coccidioidomycosis, and penicilliosis, have emerged as important health threats among travelers to regions of the world where these infections are endemic. Travelers have developed fungal infections as a result of a wide range of recreational and work activities, many of which have involved well-recognized risk factors for these diseases. In some instances, infections have been acquired during short trips, whereas, in other instances, infection has been acquired during a longer period of residence in an area where the infection is endemic. Travelers need to be made aware of the risks of acquiring mycotic diseases when visiting such regions. Health care providers need to consider these infections in their differential diagnosis among returning travelers with respiratory illness and should be familiar with the treatment and prevention of these diseases.

Comparison of visual and spectrophotometric methods of broth microdilution MIC end point determination and evaluation of a sterol quantitation method for in vitro susceptibility testing of fluconazole and itraconazole against trailing and nontrailing Candida isolates

Visual determination of MIC end points for azole antifungal agents can be complicated by the trailing growth phenomenon. To determine the incidence of trailing growth, we performed testing of in vitro susceptibility to fluconazole and itraconazole using the National Committee for Clinical Laboratory Standards broth microdilution M27-A reference procedure and 944 bloodstream isolates of seven Candida spp., obtained through active population-based surveillance between 1998 and 2000. Of 429 C. albicans isolates, 78 (18.2%) showed trailing growth at 48 h in tests with fluconazole, and 70 (16.3%) showed trailing in tests with itraconazole. Of 118 C. tropicalis isolates, 70 (59.3%) showed trailing growth in tests with fluconazole, and 35 (29.7%) showed trailing in tests with itraconazole. Trailing growth was not observed with any of the other five Candida spp. tested (C. dubliniensis, C. glabrata, C. krusei, C. lusitaniae, and C. parapsilosis). To confirm whether or not isolates that showed trailing growth in fluconazole and/or itraconazole were resistant in vitro to these agents, all isolates that showed trailing growth were retested by the sterol quantitation method, which measures cellular ergosterol content rather than growth inhibition after exposure to azoles. By this method, none of the trailing isolates was resistant in vitro to fluconazole or itraconazole. For both agents, a 24-h visual end point or a spectrophotometric end point of 50% reduction in growth relative to the growth control after 24 or 48 h of incubation correlated most closely with the result of sterol quantitation. Our results indicate that MIC results determined by either of these end point rules may be more predictive of in vivo outcome for isolates that give unclear visual end points at 48 h due to trailing growth.

Coccidioidomycosis in India: report of a second imported case

We describe a fatal case of imported coccidioidomycosis in India in a 22-year-old male who worked in Tucson, Arizona, approximately four years prior to his illness. The diagnosis was based on the presence of characteristic spherules with endospores in biopsy tissue of lymph nodes, bone and pus from a chronic discharging sinus in the left gluteal region and isolation of Coccidioides immitis in culture. C. immitis is one of the most infectious and virulent fungal pathogens and poses a serious occupational hazard for laboratory personnel, especially in areas where the disease is not endemic. To reduce the role of laboratory-acquired infection, all procedures that involve manipulation of cultures of C. immitis should, whenever possible, be conducted in a biological safety cabinet.

Epidemiology and Prevention of Invasive Aspergillosis

Aspergillus species are the most common causes of invasive mold infections in immunocompromised persons. This review examines the available information regarding the rising incidence of invasive aspergillosis in different high-risk groups, including persons with acute leukemia, hematopoietic stem cell transplant recipients, and liver and lung transplant recipients. The risk factors for infection in these groups are discussed. Because Aspergillus species are widespread in the environment, it is difficult to link specific sources and exposures to the development of human infections. However, molecular strain typing and other studies indicate that a significant number of Aspergillus infections are now being acquired outside the health care setting, either before patients are admitted to hospital, or after they have been discharged. The role of environmental control measures and antifungal drug prophylaxis in the prevention of hospital- and community-acquired aspergillosis is discussed.

Counterpoint: invasive aspergillosis and the environment--rethinking our approach to prevention

Preventive measures are important in the control of invasive aspergillosis (IA) because diagnosis is difficult and the outcome of treatment is poor. If effective strategies are to be devised, it will be essential to have a clearer understanding of the sources and routes of transmission of Aspergillus species. Nosocomial outbreaks of IA highlight the fact that Aspergillus spores are common in the hospital environment. However, in general, such outbreaks are uncommon. Most cases of IA are sporadic in nature, and many of them are now being acquired outside of the hospital setting. Housing patients in high-energy particulate air-filtered hospital rooms helps prevent IA, but it is feasible and cost-effective only for the highest-risk groups and for limited periods. Control measures, which are designed to protect patients from exposure to spores outside the hospital, are even more difficult. Nevertheless, now that high-risk patients are spending more time outside of the hospital, the cost benefits of antifungal prophylaxis and other preventive measures require careful evaluation.

Trends in antifungal drug susceptibility of Cryptococcus neoformans isolates in the United States: 1992 to 1994 and 1996 to 1998

The antifungal drug susceptibilities of two collections of Cryptococcus neoformans isolates obtained through active laboratory-based surveillance from 1992 to 1994 (368 isolates) and 1996 to 1998 (364 isolates) were determined. The MICs of fluconazole, itraconazole, and flucytosine were determined by the National Committee for Clinical Laboratory Standards broth microdilution method; amphotericin B MICs were determined by the E-test. Our results showed that the MIC ranges, the MICs at which 50% of isolates are inhibited (MIC(50)s), and the MIC(90)s of these four antifungal agents did not change from 1992 to 1998. In addition, very small numbers of isolates showed elevated MICs suggestive of in vitro resistance. The MICs of amphotericin B were elevated (>or=2 microg/ml) for 2 isolates, and the MICs of flucytosine were elevated (>or=32 microg/ml) for 14 isolates. Among the azoles, the fluconazole MIC was elevated (>or=64 microg/ml) for 8 isolates and the itraconazole MIC (>or=1 microg/ml) was elevated for 45 isolates. Analysis of 172 serial isolates from 71 patients showed little change in the fluconazole MIC over time. For isolates from 58 patients (82% of serial cases) there was either no change or a twofold change in the fluconazole MIC. In contrast, for isolates from seven patients (12% of serial cases) the increase in the MIC was at least fourfold. For isolates from another patient there was a 32-fold decrease in the fluconazole MIC over a 1-month period. We conclude that in vitro resistance to antifungal agents remains uncommon in C. neoformans and has not significantly changed with time during the past decade.

Antifungal susceptibility testing: practical aspects and current challenges

Development of standardized antifungal susceptibility testing methods has been the focus of intensive research for the last 15 years. Reference methods for yeasts (NCCLS M27-A) and molds (M38-P) are now available. The development of these methods provides researchers not only with standardized methods for testing but also with an understanding of the variables that affect interlaboratory reproducibility. With this knowledge, we have now moved into the phase of (i) demonstrating the clinical value (or lack thereof) of standardized methods, (ii) developing modifications to these reference methods that address specific problems, and (iii) developing reliable commercial test kits. Clinically relevant testing is now available for selected fungi and drugs: Candida spp. against fluconazole, itraconazole, flucytosine, and (perhaps) amphotericin B; Cryptococcus neoformans against (perhaps) fluconazole and amphotericin B; and Aspergillus spp. against (perhaps) itraconazole. Expanding the range of useful testing procedures is the current focus of research in this area.

Trends in mortality due to invasive mycotic diseases in the United States, 1980-1997

To determine national trends in mortality due to invasive mycoses, we analyzed National Center for Health Statistics multiple-cause-of-death record tapes for the years 1980 through 1997, with use of their specific codes in the International Classification of Diseases, Ninth Revision (ICD-9 codes 112.4-118 and 136.3). In the United States, of deaths in which an infectious disease was the underlying cause, those due to mycoses increased from the tenth most common in 1980 to the seventh most common in 1997. From 1980 through 1997, the annual number of deaths in which an invasive mycosis was listed on the death certificate (multiple-cause [MC] mortality) increased from 1557 to 6534. In addition, rates of MC mortality for the different mycoses varied markedly according to human immunodeficiency virus (HIV) status but were consistently higher among males, blacks, and persons > or =65 years of age. These data highlight the public health importance of mycotic diseases and emphasize the need for continuing surveillance.

Molecular epidemiology of Candida albicans strains isolated from the oropharynx of HIV-positive patients at successive clinic visits

Candida albicans strain diversity and fluconazole resistance were prospectively analyzed in oral strains from 29 adult human immunodeficiency virus (HIV)-positive patients followed for > 1 year who had five or more culture-positive clinic visits. Molecular typing consisted of genomic blots probed with the Ca3 repetitive element. Sixteen patients had one or more episodes of oropharyngeal candidiasis (OPC), 12 (75%) maintained the original genotype, whereas the remaining four patients had a succession of 2-3 genotypes. The original genotype, either alone or mixed with another strain or with non-C. albicans Candida spp., was recovered from oral lesions in 13 of 15 evaluable (86.7%) patients. C. dubliniensis was the infecting yeast in the remaining two patients. Different patterns of fluconazole resistance occurred in three OPC patients. One patient's infecting strain became less susceptible. A second patient was infected with a resistant genotype and a progressively more susceptible minor genotype variant. C. dubliniensis isolates from the third patient varied in susceptibility. Thirteen colonized patients who never developed OPC harbored a greater variety of C. albicans genotypes (2-6) than their infected counterparts (P = 0.35). OPC patients maintained their original endogenous C. albicans strains for prolonged periods, whether or not they demonstrated decreased in vitro susceptibility to fluconazole. The adaptation and maintenance of an endogenous C. albicans strain within its host may be linked to as yet uncharacterized factors.

Sporothrix schenckii sensitivity to voriconazole, itraconazole and amphotericin B

One hundred clinical isolates of Sporothrix schenckii were tested against voriconazole, itraconazole and amphotericin B using a modification of the NCCLS M27-A in vitro yeast susceptibility testing procedure. NCCLS M38-P for moulds was not used because yeast forms may have been present when the test isolates were incubated at 35 +/- 1 degrees C. The minimum inhibitory concentration (MIC) values were: voriconazole 0.5-8 (geometric mean titer 6.50) microg ml(-1) ; itraconazole 0.03-8 (geometric mean titer 1.56) microg ml(-1); and amphotericin B 0.25-2 (geometric mean titer 1.23) microg ml(-1). The minimum fungicidal concentration (MFC) values were: voriconazole 2-8 (geometric mean titer 7.67) microg ml(-1); itraconazole 0.125-8 (geometric mean titer 7.41) microg ml(-1); and amphotericin B 0.125-2 (geometric mean titer 1.53) microg ml(-1). Based upon MIC values, sensitivity to amphotericin B is strain-dependent. S. schenckii is more sensitive to itraconazole than voriconazole based upon a comparison of MIC geometric means, even though the MIC ranges were essentially the same.

In vitro antifungal susceptibility methods and clinical implications of antifungal resistance

As new antifungal agents are introduced for the treatment of infections caused by yeasts and filamentous fungi (moulds), it is important that reliable methods are available for the in vitro testing of both new and established agents. The ultimate goal of in vitro testing is the prediction of the clinical outcome of therapy. The use of the M27-A procedures that were developed by the US National Committee for Clinical Laboratory Standards (NCCLS) has led to increased interlaboratory agreement of minimum inhibitory concentrations (MICs) for yeasts and has facilitated the establishment of interpretive breakpoints for fluconazole and itraconazole. The clinical relevance and limitations of these breakpoints are discussed elsewhere. The focus of this paper is to review the advantages and disadvantages of the available methods for antifungal susceptibility testing of yeasts and moulds as well as the clinical implications of in vitro antifungal resistance.

Gastrointestinal basidiobolomycosis in Arizona: clinical and epidemiological characteristics and review of the literature

Gastrointestinal basidiobolomycosis (GIB) is an unusual fungal infection that is rarely reported in the medical literature. From April 1994 through May 1999, 7 cases of GIB occurred in Arizona, 4 from December 1998 through May 1999. We reviewed the clinical characteristics of the patients and conducted a case-control study to generate hypotheses about potential risk factors. All patients had histopathologic signs characteristic of basidiobolomycosis. Five patients were male (median age, 52 years; range, 37--59 years) and had a history of diabetes mellitus (in 3 patients), peptic ulcer disease (in 2), or pica (in 1). All patients underwent partial or complete surgical resection of the infected portions of their gastrointestinal tracts, and all received itraconazole postoperatively for a median of 10 months (range, 3--19 months). Potential risk factors included prior ranitidine use and longer residence in Arizona. GIB is a newly emerging infection that causes substantial morbidity and diagnostic confusion. Further studies are needed to better define its risk factors and treatment.

Use of a repetitive DNA probe to type clinical and environmental isolates of Aspergillus flavus from a cluster of cutaneous infections in a neonatal intensive care unit

Aspergillus flavus is second to A. fumigatus as a cause of invasive aspergillosis, but no standard method exists for molecular typing of strains from human sources. A repetitive DNA sequence cloned from A. flavus and subcloned into a pUC19 vector, pAF28, was used to type 18 isolates from diverse clinical, environmental, and geographic sources. The restriction fragment length polymorphisms generated with EcoRI- or PstI-digested genomic DNA and probed with digoxigenin-labeled pAF28 revealed complete concordance between patterns. Eighteen distinct fingerprints were observed. The probe was used to investigate two cases of cutaneous A. flavus infection in low-birth-weight infants in a neonatal intensive care unit (NICU). Both infants were transported by the same ambulance and crew to the NICU on the same day. A. flavus strains of the same genotype were isolated from both infants, from a roll of tape used to fasten their umbilical catheters, from a canvas bag used to store the tape in the ambulance, and from the tape tray in the ambulance isolette. These cases highlight the need to consider exposures in critically ill neonates that might occur during their transport to the NICU and for stringent infection control practices. The hybridization profiles of strains from a second cluster of invasive A. flavus infections in two pediatric hematology-oncology patients revealed a genotype common to strains from a definite case patient and a health care worker. A probable case patient was infected with a strain with a genotype different from that of the strain from the definite case patient but highly related to that of an environmental isolate. The high degree of discrimination and reproducibility obtained with the pAF28 probe underscores its utility for typing clinical and environmental isolates of A. flavus.

Quantitation of Candida albicans ergosterol content improves the correlation between in vitro antifungal susceptibility test results and in vivo outcome after fluconazole treatment in a murine model of invasive candidiasis

MIC end point determination for the most commonly prescribed azole antifungal drug, fluconazole, can be complicated by "trailing" growth of the organism during susceptibility testing by the National Committee for Clinical Laboratory Standards approved M27-A broth macrodilution method and its modified broth microdilution format. To address this problem, we previously developed the sterol quantitation method (SQM) for in vitro determination of fluconazole susceptibility, which measures cellular ergosterol content rather than growth inhibition after exposure to fluconazole. To determine if SQM MICs of fluconazole correlated better with in vivo outcome than M27-A MICs, we used a murine model of invasive candidiasis and analyzed the capacity of fluconazole to treat infections caused by C. albicans isolates which were trailers (M27-A MICs at 24 and 48 h, </=1.0 and >/=64 microg/ml, respectively; SQM MIC, </=1.0 microg/ml), as well as those which were fluconazole sensitive (M27-A and SQM MIC, </=1.0 microg/ml) and fluconazole resistant (M27-A MIC, >/=64 microg/ml; SQM MIC, 54 microg/ml). Compared with the untreated controls, fluconazole therapy increased the survival of mice infected with a sensitive isolate and both trailing isolates but did not increase the survival of mice infected with a resistant isolate. These results indicate that the SQM is more predictive of in vivo outcome than the M27-A method for isolates that give unclear MIC end points due to trailing growth in fluconazole.

In vitro activities of voriconazole, itraconazole, and amphotericin B against Blastomyces dermatitidis, Coccidioides immitis, and Histoplasma capsulatum

The in vitro activity of voriconazole was compared to those of itraconazole and amphotericin B against the mold forms of 304 isolates of three dimorphic fungi, Blastomyces dermatitidis, Coccidioides immitis, and Histoplasma capsulatum. MICs were determined by a broth microdilution adaptation of the National Committee for Clinical Laboratory Standards M27-A procedure. RPMI 1640 medium was used for tests with voriconazole and itraconazole, whereas Antibiotic Medium 3 with 2% glucose was used for amphotericin B. Minimum fungicidal concentrations (MFCs) were also determined. Amphotericin B was active against all three dimorphic fungi, with MICs at which 90% of the isolates tested are inhibited (MIC(90)s) of 0.5 to 1 microg/ml. Itraconazole had MIC(90)s of 0.06 microg/ml for H. capsulatum, 0.125 microg/ml for B. dermatitidis, and 1 microg/ml for C. immitis. The MIC(90)s of voriconazole were 0.25 microg/ml for all three fungi. Amphotericin B was fungicidal for B. dermatitidis and H. capsulatum with MFCs at which 90% of strains tested are killed (MFC(90)s) of 0.5 and 2 microg/ml, respectively. It was less active against C. immitis, with MFCs ranging from 0.5 to >16 microg/ml. Voriconazole and itraconazole were lethal for most isolates of B. dermatitidis, with MFC(50)s and MFC(90)s of 0.125 and 4 microg/ml, respectively. Both azoles were fungicidal for some isolates of H. capsulatum, with MFC(50)s of 2 and 8 microg/ml for itraconazole and voriconazole, respectively; neither had a lethal effect upon C. immitis. Our results suggest that voriconazole possesses promising activity against these important human pathogens.