Once-daily gentamicin administration for community-associated methicillin resistant Staphylococcus aureus in an in vitro pharmacodynamic model: preliminary reports for the advantages for optimizing pharmacodynamic index.

PURPOSE: Community-associated methicillin resistant Staphylococcus aureus (CAMRSA) infections are increasing. Although gentamicin (GEN) is usually susceptible against CA-MRSA, GEN is rarely considered for treatment as monotherapy. We employed an in vitro pharmacodynamic model (IVPDM) to compare efficacies of GEN against CA-MRSA with two dosing regimens [thrice-daily (TD), once-daily (OD)]. MATERIALS AND METHODS: Using two strains of CA-MRSA, we adopted IVPDM comprised of two-compartments with a surface-to-volume ratio of 5.34 cm(-1). GEN regimens were simulated with human pharmacokinetic data of TD and OD. Experiments were performed over 48 hours in triplicate for each strain and dosing regimen. RESULTS: MICs of GEN for YSSA1 and YSSA15 were 1 and 2 mg/L, respectively. In OD, indices of peak/MIC were > 8.6 at least, in contrast to < 6.4 in TD. A > or = 3-log(10) reduction in CFU/mL was demonstrated prior to 4 hours in TD and OD, and continued until 8 hours for both strains. However, reductions in the colony counts at 24 and 48 hours were significantly larger for OD compared to TD in both strains (p < 0.001). During TD, resistance developed in YSSA1 and small colony variants (SCVs) were documented in YSSA15. No resistance or SCVs were observed during OD in both strains. CONCLUSION: TD and OD showed the same killing slopes until 8 hours. After the 24 hours of experiments, OD of GEN would be advantageous not only in having more reductions in colony counts, but also suppressing the development of resistance or SCVs for 48 hours.

Caspofungin use in daily clinical practice for treatment of invasive aspergillosis: results of a prospective observational registry.

BACKGROUND: A prospective observational registry assessed real world experience with caspofungin monotherapy or combination therapy for the initial or salvage treatment of proven or probable invasive aspergillosis (IA). METHODS: Data were collected from April 2006 to September 2007 for patients treated with caspofungin for a single episode of IA. Clinical effectiveness was categorized as favorable (complete or partial) or unfavorable (stable disease or failure) at the end of caspofungin therapy (EOCT). RESULTS: Consecutive patients (n = 103) with proven or probable IA (per EORTC/MSG criteria) were identified from 11 countries. Malignancy (76.7%), neutropenia (64.1%), allogeneic hematopoietic stem cell transplantation (HSCT, 22.3%), solid organ transplantation (8.7%), autologous HSCT (4.9%), and HIV/AIDS (2.9%) were the most common underlying conditions. Most patients (84.5%) had pulmonary IA. Aspergillus fumigatus was the most frequently isolated species. The majority of patients received caspofungin monotherapy (82.5%) primarily as salvage therapy (82.4%). The main reason for switching to salvage therapy was clinical failure of the first-line therapy (69%). A favorable response at EOCT was seen in 56.4% (57/101) of patients overall, including 56.5% (48/85) and 56.3% (9/16) of patients receiving caspofungin monotherapy and combination therapy, respectively. Favorable response rates in clinically relevant subgroups were: malignancy, 51.9% (41/79); allogeneic HSCT, 56.5% (13/23); and neutropenia at time of hospitalization, 53.0% (35/66). There was a 72.3% (73/101) survival at 7 days after EOCT. Serious adverse events related to caspofungin were reported in 4 cases (3.9%); 3 patients (2.9%) discontinued treatment due to an adverse event related to caspofungin. CONCLUSIONS: Caspofungin was both effective and well tolerated among high-risk patient groups such as those with neutropenia and active malignancies.

Cytomegalovirus ventriculoencephalitis after unrelated double cord blood stem cell transplantation with an alemtuzumab-containing preparative regimen for Philadelphia-positive acute lymphoblastic leukemia.

Despite the prophylaxis and preemptive strategies using potent antiviral agents, cytomegalovirus (CMV) remains a major infectious cause of morbidity and mortality in allogeneic stem cell transplantation (SCT) recipients. Delayed immune reconstitution after SCT, such as cord blood and T-cell depleted SCT with the use of alemtuzumab, has been associated with an increased frequency of CMV disease as well as CMV reactivation. CMV disease involving central nervous system is an unusual presentation in the setting of SCT. We report a case of CMV ventriculoencephalitis after unrelated double cord blood SCT with an alemtuzumab-containing preparative regimen for Philadelphia-positive acute lymphoblastic leukemia.

Immunomodulatory effects of antifungal agents on the response of human monocytic cells to Aspergillus fumigatus conidia.

We evaluated the immunomodulatory effects of three different classes of antifungal agents on the human monocytic cell line, THP-1, which had been stimulated in vitro with Aspergillus fumigatus conidia. Cells treated with amphotericin B (AmB), micafungin (MF), and voriconazole (VCZ), at concentrations not affecting cell viability, reduced production of tumor necrosis factor (TNF)-alpha in response to conidia, with the greatest reduction noted with VCZ. The reduction of TNF-alpha production correlated with TNF-alpha gene expression assessed by PCR and nuclear factor kappaB (NF kappaB) levels. Co-stimulation with granulocyte-macrophage colony stimulating factor abolished immunomodulatory effects of the drugs. Antifungal agents affect the immune reaction caused by A. fumigatus conidia in stimulated monocytes at clinically relevant drug concentrations. Because drugs with different mechanisms of action produced this effect, this suggests that it is the result of factors mediated by the cells. The impact of these immunomodulatory effects needs assessment.

Comparison of quantitative cytomegalovirus real-time PCR in whole blood and pp65 antigenemia assay: clinical utility of CMV real-time PCR in hematopoietic stem cell transplant recipients.

Successful preemptive therapy for cytomegalovirus (CMV) infection in transplant patients depends on the availability of sensitive, specific, and timely diagnostic tests for CMV infection. Although the pp65 antigenemia assay has been widely used for this purpose, real-time quantification of CMV DNA has recently been recognized as an alternative diagnostic approach. However, the guidelines for antiviral therapy based on real-time quantitative polymerase chain reaction (RQ-PCR) have yet to be established. From November 2004 to March 2005, a total of 555 whole blood samples from 131 hematopoietic stem cell transplant (HSCT) recipients were prospectively collected. RQ-PCR was conducted using an Artus CMV LC PCR kit (QIAGEN). Both qualitative and quantitative correlations were drawn between the two methods. Exposure to the antiviral agent influenced the results of the two assays. Additionally, the discrepancy was observed at low levels of antigenemia and CMV DNA load. Via ROC curve analysis, the tentative cutoff value for preemptive therapy was determined to be approximately 2x10(4) copies/mL (sensitivity, 80.0%; specificity, 50.0%) in the high risk patients, and approximately 3x10(4) copies/mL (sensitivity, 90.0%; specificity, 70.0%) in the patients at low risk for CMV disease. Further study to validate the optimal cutoff value for the initiation of preemptive therapy is currently underway.

Two variants of staphylococcal cassette chromosome mec type IVA in community-associated meticillin-resistant Staphylococcus aureus strains in South Korea.

Meticillin-resistant Staphylococcus aureus (MRSA) strains harbouring staphylococcal cassette chromosome mec (SCCmec) type IVA are known to be more prevalent in South Korea than in other countries. Variations in the SCCmec IVA structure have been identified, including in sequence type (ST) 1 and ST72 strains. This study compared and investigated the genetic characteristics of two subtypes common in South Korea. Type IVA SCCmec of ST1 strains was characterized by type IV features with the linearized pUB110 at the junkyard (J) 3 region. However, that of ST72 strains carried a variant class B mec complex, ccrA2, with an identity of approximately 96 % and the linearized pUB110 at the J3 region. In SCCmec of ST72 strains, the organization of the class B variant and the J3 region may be more similar to that of type IA than to other types, but the ccr type and other J regions seemed to be derived from type IV. These genetic characteristics showed that type IVA appears to result from the dynamic genetic exchange and recombination of SCC DNA.

Emergence of community-associated methicillin-resistant Staphylococcus aureus strains as a cause of healthcare-associated bloodstream infections in Korea.

BACKGROUND: The prevalence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) strains causing bloodstream infection (BSI) has not been studied in Korea. OBJECTIVE: We sought to determine the prevalence of CA-MRSA strains among isolates recovered from patients with MRSA BSIs and to explore epidemiological changes in Korea. We also sought to evaluate clinical characteristics relevant to the development of healthcare-associated BSIs. METHODS: We prospectively collected consecutive MRSA isolates from patients with BSI at 4 hospitals from July 1 through November 30, 2007, and we also included MRSA isolates recovered from culture of blood samples collected during a previous year (October 1, 2004 through September 30, 2005) at a different hospital. Molecular typing studies were performed, including pulsed-field gel electrophoresis (PFGE), multilocus sequence typing, Staphylococcus protein A (spa) typing, and staphylococcal cassette chromosome mec (SCCmec) typing. We compared the clinical characteristics and outcomes of patients with healthcare-associated BSI due to CA-MRSA strains with those of patients with healthcare-associated BSI due to healthcare-associated MRSA (HA-MRSA) strains. RESULTS: There were 76 cases of MRSA BSI, of which 4 (5.3%) were community-associated and 72 (94.7%) were healthcare-associated. Among the 72 HA-MRSA BSIs, 18 (25%) were community onset, and 54 (75%) were hospital onset. PFGE type D-ST72-spa B-SCCmec type IVA MRSA, the predominant genotype of CA-MRSA in Korea, accounted for 19 (25%) of all 76 MRSA BSIs, including 17 (23.6%) of 72 HA-MRSA BSIs and 11 (20.8%) of 53 hospital-onset HA-MRSA BSIs. Patients with healthcare-associated BSIs due to CA-MRSA strains carrying SCCmec type IVA tended to have fewer healthcare-associated risk factors, compared with patients with healthcare-associated BSIs due to HA-MRSA strains carrying other SCCmec types. The presence of a central venous catheter or other invasive device was the only independent factor differentiating patients infected with hospital-associated genotype strains from patients infected with other strains. Clinical outcomes were similar between both groups. CONCLUSIONS: CA-MRSA strains are emerging as a major cause of BSI in healthcare settings in Korea. This changing epidemiology of MRSA poses a challenge to public health and infection control in hospital settings.

Construction of internal control for the quantitative assay of Aspergillus fumigatus using real-time nucleic acid sequence-based amplification.

We have developed a scheme for quantitative real-time (RTi) nucleic acid sequence-based amplification (NASBA) for the detection of Aspergillus fumigatus using internal control (IC) RNA. Construction of IC RNA began with the synthesis of nontarget sequences from Clavibacter michiganensis subsp. sepedonicus by a primary polymerase chain reaction (PCR) step, followed by a secondary PCR step using chimeric primers to produce a chimeric sequence including a T7 promoter region. Finally, chimeric IC RNAs were constructed by the use of in vitro transcription. The assay detected A. fumigatus within a range of 10(4) to 10(8) copies/mL of RNA and 10(0) to 10(8) cells. When the assay was performed with the target and IC RNA in 1 reaction in a single tube, there was little interference of the IC RNA in the measurement of the amount of target. The amount of RNA calculated using the assay was not significantly different from the amount of input RNA as indicated by Bland-Altman analysis. The IC RNA we constructed can be used in RTi-NASBA for quantitative detection of Aspergillus with good precision and accuracy.

Current antimicrobial usage for the management of neutropenic fever in Korea: a nationwide survey.

A nationwide questionnaire-based survey was performed to evaluate the current clinical practices for the management of neutropenic fever in hematology units and hematopoietic stem cell transplantation (HSCT) centers throughout Korea. A 86.9% response rate was obtained from a total of 46 doctors and practical policies of the 33 sites were analysed. Approximately 42.4% and 84.8% of the sites responded that they used oral fluoroquinolone as prophylaxis for neutropenic patients receiving chemotherapy and HSCT, respectively. Additionally, 42.4% of the sites responded that they used antifungal prophylaxis in the chemotherapy groups whereas 90.9% of the sites responded that they used antifungal prophylaxis in HSCT recipients. Approximately half of the responding sites prescribed combination regimen with 3rd or 4th cephalosporin plus aminoglycoside as a first-line therapy. Most of the sites considered persistent fever for 2-4 days or aggravated clinical symptoms for 1-2 days as failure of the first-line regimen, and they changed antibiotics to second-line regimens that varied widely among the sites. Twenty-seven sites (84.4%) responded that they considered adding an antifungal agent when fever persisted for 5-7 days despite antibacterial therapy. Amphotericin B deoxycholate was preferred as a first-line antifungal, which was probably due to the limitations of the national health insurance system. The role of oral antibiotics in the management of neutropenic fever still accounted for a small portion. To the best of our knowledge, this survey is the first report to examine the practical policies currently in place for the management of neutropenic fever in Korea and the results of this survey may help to establish a Korean guideline in the future.

Gemtuzumab ozogamicin in combination with attenuated doses of standard induction chemotherapy can successfully induce complete remission without increasing toxicity in patients with acute myeloid leukemia aged 55 or older.

BACKGROUND: In this study, the effectiveness and safety of combining gemtuzumab ozogamicin (GO) with an abbreviated schedule of standard induction chemotherapy were assessed in 37 patients (aged > or =55) yr with previously untreated acute myeloid leukemia (AML). METHODS: GO was administered at a dose of 6 mg/m(2) as a single 2-h intravenous infusion on day 1. Following GO, an abbreviated schedule of induction chemotherapy consisting of idarubicin (12 mg/m(2)/d, days 2-4), and N4-behenoyl-1-beta-arabinofuranosyl cytosine (300 mg/m(2)/d, days 2-6) was given. RESULTS: Thirty-seven patients were treated with GO in combination with chemotherapy. Complete remission (CR) and CR with incomplete platelet recovery were achieved in 28 patients (75.7%) and one patient (2.7%) respectively. Two patients (5.4%) died during induction and two patients (5.4%) with grade 4 treatment emergent adverse effects during chemotherapy did not complete induction chemotherapy. The majority of toxicities were mild and manageable. Severe myelosuppression was universal with significantly prolonged thrombocytopenic period. In total, 25 patients who received consolidation treatment, 19 patients remain alive at the time of analysis. Thirteen patients had undergone hematopoietic stem cell transplantation, three are preparing for transplantation and seven are receiving their consolidation chemotherapy course. CONCLUSION: Although only a relatively small number of cases were included in this preliminary study and the follow-up duration was short, frontline GO in combination with attenuated conventional chemotherapy was found to be effective and feasible in elderly patients with AML.

Predominance of community-associated methicillin-resistant Staphylococcus aureus strains carrying staphylococcal chromosome cassette mec type IVA in South Korea.

Studies on the molecular epidemiologic characteristics of methicillin-resistant Staphylococcus aureus (MRSA) strains have demonstrated their genetic and geographical diversity. In addition, it has been reported that there are genetic differences between community-associated (CA) and health care-associated (HA) MRSA strains. Therefore, we investigated the major epidemiologic characteristics of CA MRSA isolates in South Korea and compared them with those of HA MRSA strains. Distributions of staphylococcal chromosome cassette mec (SCCmec) types and other molecular features, including the Panton-Valentine leukocidin (PVL) gene, were studied in 138 invasive MRSA isolates. Multiplex type IVA SCCmec was identified as the major CA MRSA infection type (53.1%), with a significantly higher prevalence than in HA MRSA (P < 0.001). One major group of type IVA strains carried a larger atypical class B mec element and new subtypes of ccrA2 (96% amino acid homology). The PVL gene was detected in one USA300-like isolate only. Seven major clone types determined by combinational grouping (genetic background SCCmec typing) showed representative patterns of antimicrobial susceptibilities. We concluded that less multi-drug-resistant strains of clone types B-I and D-1 (genetic background, B and D complexes; type IVA SCCmec) predominate in CA MRSA and that international PVL-positive strains have not spread in South Korea as yet.

Comparison of the real-time nucleic acid sequence-based amplification (RTi-NASBA) with conventional NASBA, and galactomannan assay for the diagnosis of invasive aspergillosis.

We compared a real time-nucleic acid sequence-based amplification (RTi-NASBA) with conventional NASBA, galactomannan enzyme immunosorbent assay (GMEIA), and Mycology Study Group of the European Organization for Research and Treatment of Cancer (EORTC/MSG) criteria for the diagnosis of invasive aspergillosis (IA). From May 2004 to May 2005, blood samples (314 in total) were collected twice a week from 78 patients with hematologic diseases during neutropenic fever after chemotherapy or hematopoietic stem cell transplantation. Results were compared with each other on the basis of EORTC/ MSG criteria. The cutoff of conventional NASBA was set to be 3.5; GM 0.5; RTi-NASBA, 20% above the negative control. There were 22 patients with IA (7 probables and 15 possibles) and 56 patients with nonfungal infection. The Kappa statistic for RTi-NASBA versus conventional NASBA was 0.80 (0.66-0.82; p<0.001) indicating that there was fairly good accordance between two tests. RTi-NASBA showed sensitivity 0.96, specificity 0.43, positive- and negative-predictive value 0.40 and 0.96, respectively. GM showed good specificity (0.98), while the sensitivity (0.45) was poor. When we use the combination of GM with either of two NASBAs, the sensitivity was improved up to 100%. In conclusion, RTi-NASBA could be a good alternative to the conventional one for the screening of IA.

Allogeneic stem cell transplantation in first complete remission enhances graft-versus-leukemia effect in adults with acute lymphoblastic leukemia: antileukemic activity of chronic graft-versus-host disease.

The aim of the present study was to identify graft-versus-leukemia effects and the factors that affect outcome in 201 adults with acute lymphobalstic leukemia who received myeloablative allogeneic stem cell transplantation from matched sibling or unrelated donors (1995-2004). One hundred seventy-eight (88.6%) of these patients had high-risk criteria, and 151 (75.1%) patients were transplanted in first complete remission (CR). All patients received unmodified stem cell grafts (185 bone marrow and 16 peripheral blood) following total- body irradiation-containing myeloablative preparations. Graft-versus-host disease (GVHD) prophylaxis was uniformly attempted by administering calcineurin inhibitor plus methotrexate. After a median follow-up of 63 months (range: 25+ to 139+ months) for surviving transplants, disease-free survival at 5 years was 47.8% for all patients and 60.3% for patients in the first CR. No difference in transplantation outcome was observed between sibling and unrelated transplants in the first CR. The most powerful predictive factor affecting transplantation outcome was disease status at transplantation (the first CR versus beyond the first CR, P<.001). Chronic GVHD (cGVHD), especially limited type, was also found to have a significant antileukemic effect. Interestingly, the influence of cGVHD on relapse risk was prominent in patients with chromosomal translocations or normal cytogenetics.

Intravenous itraconazole vs. amphotericin B deoxycholate for empirical antifungal therapy in patients with persistent neutropenic fever.

BACKGROUND: Amphotericin B dexoycholate is currently the standard empirical antifungal therapy for neutropenic patients with hematologic malignancies and who also have persistent fever that does not respond to antibacterial therapy. The antifungal triazoles offer a potentially safer and effective treatment alternative to Amphotericin B dexoycholate. METHODS: We assessed the efficacy and safety of intravenous itraconazole, as compared with the efficacy and safety of amphotericin B deoxycholate, as an empirical antifungal therapeutic agent in a matched case-control clinical trial from June 2004 to August 2005. RESULTS: Efficacy was evaluated in 96 patients (48 received itraconazole and 48 received amphotericin B deoxycholate) and all the patients who received the study drugs were evaluated for safety. The baseline demographic characteristics were well matched. The overall success rates were 47.9% for itraconazole and 43.8% for amphotericin B deoxycholate (% difference: 4.1% [95% confidence interval for the difference: -15.8 to 24]), which fulfilled the statistical criteria for the non-inferiority of itraconazole. The proportions of patients who survived for at least seven days after discontinuation of therapy or who were prematurely discontinued from the study were not significantly different between the two groups. The rates of breakthrough fungal infections and resolution of fever during neutropenia were similar in both groups. More patients who received amphotericin B deoxycholate developed nephrotoxicity, hypokalemia or infusion-related events than did those patients who received itraconazole (nephrotoxicity: 16.7% vs. 1.8%, hypokalemia: 66.7% vs. 24.6%, and infusion-related events: 41.7% vs. 3.5%, respectively). CONCLUSIONS: Intravenous itraconazole is as effective as amphotericin B deoxycholate and it is generally better tolerated than amphotericin B deoxycholate when it is given as empirical antifungal therapy for Korean patients with persistent neutropenic fever.

Population pharmacokinetics of meropenem in febrile neutropenic patients in Korea.

Population pharmacokinetic parameters of meropenem in 57 febrile neutropenic patients and minimal inhibitory concentration (MIC) data for clinically isolated Pseudomonas aeruginosa and Escherichia coli were applied to estimate the time above the MIC (T>MIC) using the Monte Carlo simulation method. Mean population clearance (CL) and volume of distribution (V(d)) of meropenem were proportional to creatinine clearance (CL(Cr)) and body weight, respectively: CL (L/h)=9.7 x (CL(Cr)(mL/min)/120); V(d) (L)=14.6 x (body weight (kg)/61). In 1000 simulated patients treated with meropenem 0.5g or 1g every 8h, the proportions of patients who had a T>MIC less than 40% of the dosing interval were 46.3% and 39.5% for P. aeruginosa and 5.8% and 5.6% for E. coli, respectively. The overwhelming resistance of the pathogenic microorganisms, especially P. aeruginosa, in our data compared with that reported in North America suggests the importance of regions or countries as a critical factor for determining the dosage regimen of meropenem in addition to patient characteristics and pharmacokinetics.

Current trends of infectious complications following hematopoietic stem cell transplantation in a single center.

This study was to analyze the infectious complications after hematopoietic stem cell transplantation (HSCT) according to the recent changes of HSCT. Medical records of 379 adult patients who underwent HSCT consecutively at Catholic HSCT Center from January 2001 to December 2002 were reviewed retrospectively. Allogeneic HSCT accounted for 75.7% (287/379) and autologous HSCT for 24.3% (92/379). During pre-engraftment period, bacterial infection was predominant, and E. coli was still the most common organism. After engraftment, viral infection was predominant. The incidence of invasive fungal infection showed bimodal distribution with peak correlated with neutropenia and graft-versus-host disease (GVHD). The overall mortality and infection-related mortality rates according to 3 periods were as follows; during pre-engraftment, 3.16% (12/379) and 1.8% (7/379); during midrecovery period, 7.9% (29/367) and 4.1% (15/367); during late-recovery period, 26.9% (91/338), and 15.9% (54/338). Risk factors for infection-related mortality were as follows; during pre-engraftment period, fungal infection and septic shock; during the mid-recovery period, hemorrhagic cystitis and delayed engraftment; during the late-recovery period, fungal infection, chronic GVHD, and relapse. In conclusion, infection was still one of the main complications after HSCT and highly contributes to mortality. The early diagnosis and the effective vaccination strategy are needed for control of infections.

Clinical characteristics and outcomes of posttransplant lymphoproliferative disorders following allogeneic hematopoietic stem cell transplantation in Korea.

Between 1995 and 2003, seven cases of posttransplant lymphoproliferative disorder (PTLD) were identified among 1,116 patients who received allogeneic hematopoietic stem cell transplantations (HSCT) at Catholic HSCT Center (overall incidence 0.6%). Five (71.4%) patients had episodes of acute graft-versus-host-disease (GVHD) and were treated with steroids. Cervical lymphadenopathy was observed in most cases (71.4%), but clinical symptoms varied depending on the involved sites. Pathologic findings varied: 1 case of plasmacytic hyperplasia, 3 of polymorphic PTLD, 2 of diffuse large B-cell lymphoma, 1 of large T-cell lymphoma, which proved to be associated with Epstein-Barr virus (EBV). The proportion of EBV-negative PTLD was 33.3%. Five patients demonstrated a good response to treatment (treatment response rate 71.4%). The overall mortality was 42.8%, and one death was directly attributable to PTLD. The incidence of PTLD is expected to increase, based on the rising use of grafts from alternative donors and recent clinical features of PTLD manifested by a disseminated and fulminant nature. It is necessary to have a high level of suspicion when monitoring patients and readily adopt prompt and effective cellular immunotherapy for PTLD.