Drosophila melanogaster as a model to study virulence and azole treatment of the emerging pathogen Candida auris.

OBJECTIVES: Candida auris is an emerging, often MDR, yeast pathogen. Efficient animal models are needed to study its pathogenicity and treatment. Therefore, we developed a C. auris fruit fly infection model. METHODS: TollI-RXA/Tollr632 female flies were infected with 10 different C. auris strains from the CDC Antimicrobial Resistance bank panel. We used three clinical Candida albicans strains as controls. For drug protection assays, fly survival was assessed along with measurement of fungal burden (cfu/g tissue) and histopathology in C. auris-infected flies fed with fluconazole- or posaconazole-containing food. RESULTS: Despite slower in vitro growth, all 10 C. auris isolates caused significantly greater mortality than C. albicans in infected flies, with >80% of C. auris-infected flies dying by day 7 post-infection (versus 67% with C. albicans, P < 0.001-0.005). Comparison of C. auris isolates from different geographical clades revealed more rapid in vitro growth of South American isolates and greater virulence in infected flies, whereas the aggregative capacity of C. auris strains had minimal impact on their growth and pathogenicity. Survival protection and decreased fungal burden of fluconazole- or posaconazole-fed flies infected with two C. auris strains were in line with the isolates' disparate in vitro azole susceptibility. High reproducibility of survival curves for both non-treated and antifungal-treated infected flies was seen, with coefficients of variation of 0.00-0.31 for 7 day mortality. CONCLUSIONS: Toll-deficient flies could provide a fast, reliable and inexpensive model to study pathogenesis and drug activity in C. auris candidiasis.

Extrapulmonary tuberculosis active infection misdiagnosed as cancer: Mycobacterium tuberculosis disease in patients at a Comprehensive Cancer Center (2001-2005).

BACKGROUND: Extrapulmonary tuberculosis is an uncommon disease in the U.S., even in immunosuppressed cancer patients. This study evaluated characteristics and frequency of extrapulmonary tuberculosis in patients at a tertiary care referral cancer center. METHODS: The records of all consecutive patients with Mycobacterium tuberculosis diagnosed during January 2001 through April 2005 at the M. D. Anderson Cancer Center were reviewed after obtaining institutional review board approval. RESULTS: There were 26 patients with active tuberculosis during the period studied; 18 of them were cancer patients and the others had been referred for a presumed cancer but did not have cancer. The overall rate of active tuberculosis during this period was 0.2 in 1000 new cancer diagnoses. There were 18 men (69%), the median age was 54 years (range, 3-84 yrs), and 16 patients (62%) were born in the U.S. Thirteen (72%) of the 18 cancer patients had solid-organ tumors; 3 of the 5 patients with a hematologic malignancy had non-Hodgkin lymphoma. Three patients (12%) had diabetes mellitus, and 2 patients (8%) had received high-dose (>1 mg/kg of prednisone daily) corticosteroids in the previous week. No patient had a recent history (within the past 4 wks) of chemotherapy; 4 patients had neutropenia. Cough was a prominent symptom (31%), followed by bone pain (19%), dyspnea (15%), and fever (12%). Fifteen patients (58%) had extrapulmonary infection, including 5 patients with concurrent pulmonary involvement; 7 noncancer patients (88%) and 8 cancer patients (44%, P = 0.22) had extrapulmonary disease. In 11 patients (42%), the lungs were the only site of active tuberculosis. Cavitary pneumonia was seen radiographically in 3 of 16 patients (19%) with pulmonary tuberculosis. All M. tuberculosis isolates were susceptible to isoniazid, rifampin, ethambutol, and pyrazinamide; streptomycin resistance was noted in 1 of 22 (5%) isolates tested. Twenty-two patients (85%) received appropriate antituberculosis treatment; all had a clinical and radiographic response. In 3 patients (12%) the cause of death was attributed to M. tuberculosis disease; 2 of 18 cancer patients (11%) died of progressive M. tuberculosis, and they had advanced solid-organ cancer, whereas 1 of 8 patients (13%) without cancer died and the tuberculosis diagnosis was made only on postmortem examination. Univariate analysis showed no significant differences in patients or disease characteristics between non-U.S.-born and U.S.-born patients, whereas noncancer patients (age 52 yrs) and those with extrapulmonary tuberculosis (age 53 yrs) were younger compared with cancer patients (63 yrs; P < 0.007) and those with pulmonary disease (age 60 yrs; P = 0.09). CONCLUSIONS: Extrapulmonary tuberculosis was relatively common in younger patients with active M. tuberculosis infection, and was often initially misdiagnosed as cancer.