Coexisting with Clonal Evolution and BCR-ABL Mutant in CML Patients Treated with Second-generation Tyrosine Kinase Inhibitors Predict the Discrepancy of in vitro Drug Sensitivity / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: Second-generation tyrosine kinase inhibitors (second TKIs) such as nilotinib and dasatinib control the activity of most ABL kinase domain mutations observed in patients with imatinib resistance. Although in vitro data show that both agents can inhibit all mutations except T315I, some discrepancies have been observed in a small subset of mutation clones. Cytogenetic clonal evolution is the important resistance mechanism of chronic myeloid leukemia (CML). Accordingly, we observed the clinical significance of coexisting with clonal evolution and BCR-ABL mutant in CML patients treated with second TKIs. MATERIALS AND METHODS: We monitored BCR-ABL transcript kinetics, interrelationship of clones expressing non-mutated and mutant transcripts and clonal aberrations within Philadelphia (Ph) positive and negative clones, respectively, in eight patients with CML receiving dasatinib or nilotinib for 3~41 months. RESULTS: Clinical responses were correlated with in vitro sensitivity of the BCR-ABL mutants to the second TKIs in four patients. Four patients showed resistance to the second TKIs as compared to in vitro observations; three of them developed chromosomal abnormalities in the Ph chromosome positive or negative metaphases. Another patient lost the original mutation but acquired a more resistant new mutation and became resistant to the second TKI. CONCLUSION: Cytogenetic clonal evolution is an independent poor prognostic factor in CML, which could explain the onset of mechanisms for second TKIs resistance to ABL kinase domain mutations. The results indicate that an additional evaluation of chromosomal abnormalities is warranted when BCR-ABL mutants are more resistant than indicated by in vitro data.

In Vitro Susceptibilities of Clinical Isolates of Aspergillus Species against Echinocandins / 감염과화학요법

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 / 감염과화학요법

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 to Caspofungin and Micafungin of Clinical Isolates of Candida Species / 대한진단검사의학회지

BACKGROUND: Caspofungin and micafungin are echinochandins with potent activities against Candida species. However, in vitro susceptibility to these agents of clinical Candida isolates in Korea has not been fully surveyed. We determined minimum inhibitory concentrations (MICs) of caspofungin and micafungin against clinical isolates of Candida species. METHODS: A total of 107 blood isolates of Candida species (24 C. albicans, 25 C. tropicalis, 24 C. glabrata, 20 C. parapsilosis, 8 C. krusei, and 6 other Candida species) were tested by using the National Committee for Clinical Laboratory Standards M27-A2 broth microdilution methods. The in vitro antifungal activities and spectrum of caspofungin and micafungin were compared with those of amphotericin B, fluconazole, and itraconazole. RESULTS: Caspofungin and micafungin exhibited a broad-spectrum activity against Candida species: caspofungin MIC ranged from 0.125 to 1 microgram/mL and micafungin MIC from < or =0.03 to 1 microgram/mL. C. albicans, C. tropicalis and C. glabrata showed high susceptibility to caspofungin (MIC90, 0.25 to 0.5 microgram/mL) and micafungin (MIC90 , < or =0.03 microgram/mL), whereas C. parapsilosis was less susceptible to both echinocandins (MIC90, 1 microgram/mL). The MIC50 for caspofungin, micafungin, amphotericin B, fluconazole, and itraconazole were 0.25, < or =0.03, 0.5, 1, and 0.125 microgram/mL, respectively. Caspofungin MIC50 of C. glabrata and C. krusei isolates with decreased susceptibility to azoles were 0.25 and 0.5 microgram/mL, respectively, and micafungin MIC50 were < or =0.03 and 0.125 microgram/mL, respectively. CONCLUSIONS: These data showed an excellent in vitro activity of caspofungin and micafungin against clinical strains of Candida species, including isolates with reduced susceptibility to azoles.

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 / 감염과화학요법

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 / 감염과화학요법

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.