Trichosporon species are emerging causative agents of mycoses; most are documented in immunocompromised patients. Species identification is important for epidemiological purposes in order to better define species clinical associations and to improve antifungal treatment. Here, we studied a collection of 41 Trichosporon strains recovered from hospitalized patients in Argentina. All strains were identified by sequencing the D1/D2 domain of 26S, internal transcribed spacer (ITS) regions, and intergenic spacer 1 (IGS1) region. In addition, we determined the IGS1 region genotypes of the suspected T. asahii strains. Antifungal susceptibility of all strains was investigated. Thirty-eight of the 41 strains in this study were identified as follows: 29 T. asahii, 3 T. inkin, 3 T. montevideense, 2 T. faecale, and 1 T. dermatis. The identity of the three remaining strains could not be confirmed. Strain DMic 114126 (Culture collection of the Mycology Department (DMic), National Institute of Infectious Diseases "Dr. Carlos G. Malbrán".) may represent a T. asahii subspecies or a new Trichosporon species, strain DMic 94750 was identified as T. cf. guehoae and strain DMic 114132 as T. cf. akiyoshidainum. The distribution of T. asahii genotypes was as follows: 12 genotype 3, 9 genotype 1, 4 genotype 4, 2 genotype 5, and 2 genotype 7. Amphotericin B minimal inhibitory concentrations (MICs) were ≤1 mg/l for 78% (32/41) of the strains. Fluconazole MICs were ≥2 mg/l for 90% of the strains. However, itraconazole, voriconazole, ketoconazole, and posaconazole MICs were ≤1 mg/l for 100% of the strains. Terbinafine MICs were ≤1 mg/l for 98% 40/41 of the strains.

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We report the first case of blood infection due to Pseudozyma aphidis in Latin America. We contribute evidence showing this organism to be a potential human pathogen, and we provide new data about its identification, drug susceptibility, and treatment outcome. CASE REPORTA 6-year-old female from Córdoba, Argentina, was diagnosed with osteosarcoma of the left tibia and lung metastasis and started chemotherapy administered through a long-term indwelling central line (a central venous catheter [CVC]) on 2 September 2013 at the Hospital de niños de la Santísima Trinidad. On 2 October, she presented with febrile neutropenia and was empirically treated with ceftazidime, vancomycin, and amikacin; blood and urine samples were submitted for laboratory testing, and both cultures were negative. On 4 October, she received clindamycin due to facial edema. From 6 October to 13 November, she was transfused with platelets and red blood cells several times due to thrombocytopenia and anemia. On 5 November, she developed severe mucositis and erythroderma and was treated with ceftazidime, nystatin, amikacin, vancomycin, and fluconazole. On 13 November, she received a 1-week treatment with meropenem and liposomal amphotericin B. On 18 November, she developed conjunctival hyperemia and was treated with tobramycin. On 28 November, she underwent supracondylar amputation of the left lower limb. On 20 December, the patient presented with febrile neutropenia (white blood cells [WBCs], 1,030/mm 3 ) and was admitted to the intensive care unit (ICU) in the same hospital. Table 1 summarizes the clinical data and evolution of the case since admission. A blood sample (BS1) obtained by venipuncture and a hub blood sample (drawn through the catheter hub) (HBS1) were taken and sent to the microbiology laboratory. Yeast cells (Pseudozyma aphidis; isolate Y1) were detected in the hub blood sample after 2.6 days of incubation in a Bact/ALERT PF (bioMérieux Inc., Durham, NC). However, the patient did not show clinical signs of illness on day 3 after admission; therefore, the isolate was considered not significant and she was discharged. Four days later, the patient presented with vomiting, dehydration, and febrile neutropenia (WBCs, 200/mm 3 ) and was admitted once again at the ICU in the same institution. At that point, an empirical antibiotic treatment with ceftazidime and amikacin was initiated and a new blood sample and hub blood sample (BS2 and HBS2) were taken and processed. After 18 h of incubation, both cultures were positive for Pseudomonas aeruginosa. Four days after readmission, the patient presented with fever and severe neutropenia (WBCs, 80/ mm 3 ) and showed high (233 mg/liter) C-reactive protein levels. A blood sample and a hub blood sample (BS3 and HBS3) were taken and processed. After 12 h of incubation, the blood sample culture was positive for Escherichia coli, and 2 h later, the hub blood sample culture was positive for yeast (Y2). This isolate (Y2) had the same phenotypic features as the first yeast isolate (Y1). Six days after...

Candida dubliniensis is an emerging pathogen that can cause invasive disease in patients who have a variety of clinical conditions. C. dubliniensis is often misidentified as Candida albicans by clinical laboratories. In Argentina, incidence data are still scarce, and only one systemic infection has been reported. This study aims to determine the prevalence of C. dubliniensis in blood samples in Argentina, to evaluate a novel PCR multiplex as well as several phenotypic methods for the identification of this yeast, and to know the susceptibility profile of isolates against seven antifungal drugs. We have found that prevalence in Argentina appears to be lower than that reported in other countries, occurring only in 0.96% of the Candidemia cases recovered in 47 hospitals during a 1-year period. All C. dubliniensis clinical isolates included in this study were genetically identical when comparing ITS genes sequences. This is in agreement with the previous studies suggesting little genetic variation within this species. The novel multiplex PCR proved to be 100% sensitive and specific for the identification of C. dubliniensis. Therefore, we propose its use as a rapid and inexpensive method for laboratories having access to molecular techniques. Although no single phenotypic test has proved to be infallible, both colony morphology on tobacco agar, as well as abundant chlamydospore formation on both tobacco agar and on sunflower seed agar, may be used as a presumptive differentiation method in routine mycology laboratories. It has been suggested that C. dubliniensis may have higher propensity to develop azole antifungal drug resistance than C. albicans. In this study, one of the five clinical isolates of C. dubliniensis was resistant to fluconazole.

The molecular basis of fluconazole resistance in Cryptococcus neoformans has been poorly studied. A common azole resistance mechanism in Candida species is the acquisition of point mutations in the ERG11 gene encoding the enzyme lanosterol 14-α-demethylase, target of the azole class of drugs. In C. neoformans only two mutations were described in this gene. In order to evaluate other mutations that could be implicated in fluconazole resistance in C. neoformans we studied the genomic sequence of the ERG11 gene in 11 clinical isolates with minimal inhibitory concentration (MIC) values to fluconazole of ≥16μg/ml. The sequencing revealed the G1855A mutation in 3 isolates, resulting in the enzyme amino acid substitution G484S. These strains were isolated from two fluconazole-treated patients. This mutation would not intervene in the susceptibility to itraconazole and voriconazole.

Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) has revolutionized the identification of microorganisms in clinical laboratories because it is rapid, relatively simple to use, accurate, and can be used for a wide number of microorganisms. Several studies have demonstrated the utility of this technique in the identification of yeasts; however, its performance is usually improved by the extension of the database. Here we developed an in-house database of 143 strains belonging to 42 yeast species in the MALDI Biotyper platform, and we validated the extended database with 388 regional strains and 15 reference strains belonging to 55 yeast species. We also performed an intra- and interlaboratory study to assess reproducibility and analyzed the use of the cutoff values of 1.700 and 2.000 to correctly identify at species level. The creation of an in-house database that extended the manufacturer's database was successful in view of no incorrect identification was introduced. The best performance was observed by using the extended database and a cutoff value of 1.700 with a sensitivity of .94 and specificity of .96. A reproducibility study showed utility to detect deviations and could be used for external quality control. The extended database was able to differentiate closely related species and it has potential in distinguishing the molecular genotypes of Cryptococcus neoformans and Cryptococcus gattii.

Candida pseudorugosa is a novel species closely related to Candida rugosa for which only one case has been reported. We report the first case of a bloodstream infection in humans caused by a Candida sp. closely related to C. pseudorugosa . We contribute evidence to show this organism as a potential human pathogen that may be misidentified by conventional methods, also pointing out its lower sensitivity to azoles and other antifungal agents.