In Vitro Susceptibilities of Clinical Isolates of Aspergillus Species against Echinocandins

BACKGROUND: Echinocandins are a new class of antifungal agents with potent in vitro and in vivo activities against Aspergillus species. We investigated the in vitro activity of caspofungin and micafungin against Korean clinical Aspergillus isolates. MATERIALS AND METHODS: A total of 100 clinical isolates of Aspergillus species (32 A. fumigatus, 26 A. flavus, 22 A. niger and 20 A. terreus) were tested. The susceptibilities of caspofungin, micafungin, amphotericin B and itraconazole were established by means of the Clinical and Laboratory Standards Institute (CLSI) M38-A microdilution methods. The results for caspofungin and micafungin were evaluated by using the end points of minimum inhibitory concentrations (MIC) and minimum effective concentration (MEC, the lowest concentration that produces short and aberrant hyphal branchings microsopically). RESULTS: The MEC ranges of caspofungin and micafungin against 100 isolates of Aspergillus species were 0.06 to 0.5 microgram/mL and 16 microgram/mL unexpectedly, in 5% (5/100) and 4% (4/100) of isolates, respectively, which resulted in the loss of a consistent correlation between the two endpoint readings. The MEC50 of all Aspergillus isolates for caspofungin and micafungin were 0.25 and < or =0.03 /mL, respectively, and the MIC50 for amphotericin B and itraconazole were 0.5 and 0.25 microgram/mL, respectively. There were no species-related differences in caspofungin and micafungin MECs for Aspergillus species. CONCLUSION: This data demonstrates excellent in vitro activity of echinocandins against clinical strains of Aspergillus species.

In Vitro Susceptibilities of Clinical Isolates of Aspergillus Species against Echinocandins

BACKGROUND: Echinocandins are a new class of antifungal agents with potent in vitro and in vivo activities against Aspergillus species. We investigated the in vitro activity of caspofungin and micafungin against Korean clinical Aspergillus isolates. MATERIALS AND METHODS: A total of 100 clinical isolates of Aspergillus species (32 A. fumigatus, 26 A. flavus, 22 A. niger and 20 A. terreus) were tested. The susceptibilities of caspofungin, micafungin, amphotericin B and itraconazole were established by means of the Clinical and Laboratory Standards Institute (CLSI) M38-A microdilution methods. The results for caspofungin and micafungin were evaluated by using the end points of minimum inhibitory concentrations (MIC) and minimum effective concentration (MEC, the lowest concentration that produces short and aberrant hyphal branchings microsopically). RESULTS: The MEC ranges of caspofungin and micafungin against 100 isolates of Aspergillus species were 0.06 to 0.5 microgram/mL and 16 microgram/mL unexpectedly, in 5% (5/100) and 4% (4/100) of isolates, respectively, which resulted in the loss of a consistent correlation between the two endpoint readings. The MEC50 of all Aspergillus isolates for caspofungin and micafungin were 0.25 and < or =0.03 /mL, respectively, and the MIC50 for amphotericin B and itraconazole were 0.5 and 0.25 microgram/mL, respectively. There were no species-related differences in caspofungin and micafungin MECs for Aspergillus species. CONCLUSION: This data demonstrates excellent in vitro activity of echinocandins against clinical strains of Aspergillus species.

A Case of Bloodstream Infection Due to Fusarium oxysporum / 대한임상미생물학회지

Fusarium species are representative of the emerging group of filamentous molds, which cause respiratory and disseminated infections in immunocompromised patients. To date, only five cases of respiratory or disseminated skin infections due to Fusarium spp. have been described in Korea. Here we describe a fungemia case of Fusarium oxysporum in a 3-year old boy who was neutropenics following chemotheray for leukemia. Fever, painful macules on both extremities and phlebitis on the site of venous blood sampling developed on the day 35 of admission. All four blood cultures obtained on hospital days 37, 38, 40 and 42 yielded the same F. oxysporum. The infection was cured with a high dose (1.5 mg/kg) of amphotericin B. This case shows that Fusarium is among a few filamentous fungi that cause clinically detectable fungemias in immuncompromised hosts.

DNA Fingerprinting of Candida albicans Strains Isolated from Candidemic Patients by Polymerase Chain Reaction and Southern Hybridization Methods

BACKGROUND: Although several molecular typing methods have been used to investigate C. albicans infections, there remains no "gold standard" method by which relatedness of C. albicans strains is determined. In this study, two DNA fingerprinting methods were compared for genotyping of clinical strains of C. albicans isolated from candidemic patients. MATERIALS AND METHODS: Twenty-nine strains of C. albicans isolated from various clinical specimens (14 from blood, 7 from catheter, 4 from respiratory tract secretion, and 4 from urine) of 14 candidemic patients were analyzed. Primer 1245 and 1246 were employed for IR PCR and Southern blot hybridization method was used for C2 fingerprinting, with Ca3 and C1 as primers, after the fragmentation of DNA with EcoR1 RESULTS: IR PCR method separated 29 isolates into 9 (1245 primer), 7 (1246 primer) and 14 (combination of two primers) types, whereas C1 fingerprinting identified 16 different types. By combining the IR PCR and C1 fingerprinting methods, total of 16 different genotypes were identified among 29 isolates from 14 patients, which is the same result obtained by the C1 fingerprinting only. Using both methods, blood and non-blood isolates from each patient produced identical genotypes for 10 patients and different genotypes for 1 patient. In three patients, isolates from blood and other site of each patient showed identical patterns by IR PCR fingerprinting, but appeared different (n=1) or similar (n=2) by C1 fingerprinting. Overall, for 87% (13/15) of patients, isolates collected from catheter (6 of 7 patients), urine (4 of 4 patients), or respiratory (3 of 4 patients) were identical or similar to the corresponding blood isolates. CONCLUSION: Our study shows that C1 fingerprinting method is more discriminatory than IR PCR for the molecular typing of C. albicans isolates. For the majority of patients, blood and other site isolates had identical or similar genotypes.

DNA Fingerprinting of Candida albicans Strains Isolated from Candidemic Patients by Polymerase Chain Reaction and Southern Hybridization Methods

BACKGROUND: Although several molecular typing methods have been used to investigate C. albicans infections, there remains no "gold standard" method by which relatedness of C. albicans strains is determined. In this study, two DNA fingerprinting methods were compared for genotyping of clinical strains of C. albicans isolated from candidemic patients. MATERIALS AND METHODS: Twenty-nine strains of C. albicans isolated from various clinical specimens (14 from blood, 7 from catheter, 4 from respiratory tract secretion, and 4 from urine) of 14 candidemic patients were analyzed. Primer 1245 and 1246 were employed for IR PCR and Southern blot hybridization method was used for C2 fingerprinting, with Ca3 and C1 as primers, after the fragmentation of DNA with EcoR1 RESULTS: IR PCR method separated 29 isolates into 9 (1245 primer), 7 (1246 primer) and 14 (combination of two primers) types, whereas C1 fingerprinting identified 16 different types. By combining the IR PCR and C1 fingerprinting methods, total of 16 different genotypes were identified among 29 isolates from 14 patients, which is the same result obtained by the C1 fingerprinting only. Using both methods, blood and non-blood isolates from each patient produced identical genotypes for 10 patients and different genotypes for 1 patient. In three patients, isolates from blood and other site of each patient showed identical patterns by IR PCR fingerprinting, but appeared different (n=1) or similar (n=2) by C1 fingerprinting. Overall, for 87% (13/15) of patients, isolates collected from catheter (6 of 7 patients), urine (4 of 4 patients), or respiratory (3 of 4 patients) were identical or similar to the corresponding blood isolates. CONCLUSION: Our study shows that C1 fingerprinting method is more discriminatory than IR PCR for the molecular typing of C. albicans isolates. For the majority of patients, blood and other site isolates had identical or similar genotypes.

In-Vitro Susceptibilities of Voriconazole Against Korean Clinical Aspergillus Isolates / 대한의진균학회지

BACKGROUND: Voriconazole is a potent new triazole antifungal agent expected to be particularly useful for the treatment of invasive aspergillosis. However, in vitro susceptibility of voriconazole for clinical strains of Aspergillus species isolated in Korea has not been fully surveyed. OBJECTIVE: We determined minimum inhibitory concentrations (MICs) of voriconazole for clinical Aspergillus isolates. METHODS: A total of 100 clinical isolates of Aspergillus species (40 A. fumigatus, 24 A. flavus, 17 A. niger, 17 A. terreus and 2 A. nidulans) was tested. In vitro voriconazole susceptibility testing was accomplished utilizing the National Committee for Clinical Laboratory Standards (NCCLS) broth microdilution method M38-A. MIC of voriconazole was determined using RPMI medium at 48 h of incubation. RESULTS: Among the 100 isolates of Aspergillus species tested, 98% were inhibited by or =2 microgram/mL were 0/40 (0%) in A. fumigatus, 1/24 (4%) in A. flavus, 1/17 (6%) in A. niger, 0/17 (0%) in A. terreus, and 0/2 (0%) in A. nidulans. CONCLUSION: These data demonstrate promising in-vitro activity of voriconazole against clinical strains of Aspergillus species isolated from Korean patients.

Random Amplified Polymorphic DNA (RAPD) Analysis for Aspergillus Species Isolated from Clinical Specimens / 대한임상미생물학회지

BACKGROUND: Aspergillus species are second only to Candida species as the most commonly isolated fungi from clinical specimens. As well as the identification of the Aspergillus species, it has been necessary for epidemiological studies to differentiate between strains of the same species. We performed genotypic identification and characterization of species and strains within the genus Aspergillus by using RAPD. METHODS: A total of 63 clinical strains of Aspergillus species (including 21 A. fumigatus, 12 A. flavus, 12 A. niger, 12 A. terreus, 3 A. nidulans, and 3 A. sydowii) from 63 patients was analyzed. For RAPD alanysis, M13 primer (5'GAGGGTGGCGGTTCT3') and five random 10-mer primers (OPC-6, 7, 10, 18 and 20; Operon Technologies, USA) were used. RESULTS: The RAPD patterns by M13 primer appeared to be identical when the isolates of the same Aspergillus species were compared. Distinctive and reproducible sets of amplification products by primer M13 were observed for different Aspergillus species: 60 of 63 (95%) isolates were correctly identified by the RAPD analysis using primer M13. RAPD patterns obtained from different strains of the same Aspergillus species by five OPC primers were far more similar than those derived from different Aspergillus species, but the RAPD profiles with some OPC primers showed polymorphism among isolates of the same Aspergillus species. The application of some OPC primers made it possible to cluster the isolates of the same Aspergillus species into several groups. CONCLUSION: These results indicate that RAPD can be useful for the rapid identification of Aspergillus species and for strain typing in the epidemiological investigations.