Pneumonia due to Schizophyllum commune in a Patient with Acute Myeloid Leukemia: Case Report and Literature Review.

Schizophyllum commune is a mold in phylum Basidiomycota and is an uncommon human pathogen. Sinusitis and allergic bronchopulmonary mycosis are the two major diseases caused by S. commune. Although there have been several reports of invasive fungal diseases, most of them were invasive sinusitis. We present a case of invasive fungal pneumonia due to S. commune, developed in a patient with acute myeloid leukemia presenting neutropenic fever. The diagnosis was made by characteristic macroscopic and microscopic findings of fungal isolate and was confirmed via sequencing of internal transcribed spacer region. The patient was improved after 8 weeks of antifungal therapy based on the susceptibility result. We propose that S. commune should be considered as an emerging pathogen of invasive fungal pneumonia when a patient is under immunocompromised state. We also reviewed global literatures focused on the invasive fungal diseases caused by S. commune.

Fungal arthritis with adjacent osteomyelitis caused by Candida pelliculosa: a case report.

BACKGROUND: Candida sp. osteoarticular infection is rare and most often due to hematogenous seeding during an episode of candidemia in immunocompromised patients. However, the diagnosis can be delayed in patients with subtle symptoms and signs of joint infection without a concurrent episode of candidemia. CASE PRESENTATION: A 75-year-old woman presented with a three-year history of pain and swelling of the left knee. Candida pelliculosa was detected from the intraoperative tissue when the patient had undergone left total knee arthroplasty 32 months ago, but no antifungal treatment was performed. One year after the total knee arthroplasty, C. pelliculosa was repeatedly isolated from the left knee synovial fluid and antifungal treatment comprising amphotericin B deoxycholate and fluconazole was administered. However, joint infection had extended to the adjacent bone and led to progressive joint destruction. The patient underwent surgery for prosthesis removal and received prolonged antifungal treatment with micafungin and fluconazole. CONCLUSIONS: This case shows that C. pelliculosa, an extremely rare non-Candida albicans sp., can cause fungal arthritis and lead to irreversible joint destruction owing to delayed diagnosis and treatment.

Development of multiplex real-time PCR for rapid identification and quantitative analysis of Aspergillus species.

The identification of Aspergillus species and azole resistance is highly important for the treatment of invasive aspergillosis (IA), which requires improvements in current fungal diagnostic methods. We aimed to develop multiplex real-time PCR to identify major Aspergillus section and azole resistance. BenA and cyp51A genes were used to design primers, probes, and control DNA for multiplex PCR. Qualitative and quantitative analysis was conducted for 71 Aspergillus and 47 non-Aspergillus isolates. Further, the limit of detection (LOD) and limit of quantitation (LOQ) from hyphae or conidia were determined according to the culture time. Newly developed real-time PCR showed 100% specificity to each Aspergillus section (Fumigati, Nigri, Flavi, and Terrei), without cross-reaction between different sections. In quantitative analysis of sensitivity measurements, LOD and LOQ were 40 fg and 400 fg, respectively. Melting temperature analysis of the cyp51A promoter to identify azole resistance showed temperatures of 83.0 ± 0.3°C and 85.6 ± 0.6°C for susceptible A. fumigatus and resistant isolates with TR34 mutation, respectively. The minimum culture time and fungal colony size required for successful detection were 24 h and 0.4 cm in diameter, respectively. The developed multiplex real-time PCR can identify common Aspergillus sections quantitatively and detect presence of the TR34 mutation. Further, this method shows high sensitivity and specificity, allowing successful detection of early-stage fungal colonies within a day of incubation. These results can provide a template for rapid and accurate diagnosis of IA.

Characteristics and risk factors for mortality of invasive non-Aspergillus mould infections in patients with haematologic diseases: A single-centre 7-year cohort study.

Since mould-active azole prophylaxis has become a standard approach for patients with high-risk haematologic diseases, the epidemiology of invasive fungal infections (IFIs) has shifted towards non-Aspergillus moulds. It was aimed to identify the epidemiology and characteristics of non-Aspergillus invasive mould infections (NAIMIs). Proven/probable NAIMIs developed in patients with haematologic diseases were reviewed from January 2011 to August 2018 at Catholic Hematology hospital, Seoul, Korea. There were 689 patients with proven/probable invasive mould infections; of them, 46 (47 isolates) were diagnosed with NAIMIs. Fungi of the Mucorales order (n = 27, 57.4%) were the most common causative fungi, followed by Fusarium (n = 9, 19.1%). Thirty-four patients (73.9%) had neutropenia upon diagnosis of NAIMIs, and 13 (28.3%) were allogeneic stem cell transplantation recipients. The most common site of NAIMIs was the lung (n = 27, 58.7%), followed by disseminated infections (n = 8, 17.4%). There were 23.9% (n = 11) breakthrough IFIs, and 73.9% (n = 34) had co-existing bacterial or viral infections. The overall mortality at 6 and 12 weeks was 30.4% and 39.1%, respectively. Breakthrough IFIs (adjusted hazards ratio [aHR] = 1.99, 95% CI: 1.3-4.41, P = .031) and surgical treatment (aHR = 0.09, 95% CI: 0.02-0.45, P = .003) were independently associated with 6-week overall mortality. NAIMIs were not rare and occur as a complex form of infection often accompanied by breakthrough/mixed/concurrent IFIs and bacterial or viral infections. More active diagnostic efforts for NAIMIs are needed.

Epidemiology and Antifungal Susceptibility Profile of Aspergillus Species: Comparison between Environmental and Clinical Isolates from Patients with Hematologic Malignancies.

Global data on the epidemiology and susceptibility of Aspergillus are crucial in the management of invasive aspergillosis. Here, we aimed to determine the characteristics of clinical and environmental Aspergillus isolates, focusing mainly on hematologic malignancy patients. We prospectively collected all consecutive cases and clinical isolates of culture-positive proven/probable invasive aspergillosis patients from January 2016 to April 2018 and sampled the air inside and outside the hospital. Cryptic species-level identification of Aspergillus, antifungal susceptibilities, and cyp51 gene sequencing were performed, and clinical data were analyzed. This study was conducted as part of the Catholic Hematology Hospital Fungi Epidemiology (CAFÉ) study. A total of 207 proven/probable invasive aspergillosis and 102 clinical and 129 environmental Aspergillus isolates were included in this analysis. The incidence of proven/probable invasive aspergillosis was 1.3 cases/1,000 patient-days during the study period. Cryptic Aspergillus species accounted for 33.8%, with no differences in proportions between the clinical and environmental isolates. Section Nigri presented a high proportion (70.5%) of cryptic species, mainly from A. tubingensis and A. awamori: the former being dominant in environmental samples, and the latter being more common in clinical isolates (P < 0.001). Of 91 A. fumigatus isolates, azole-resistant A. fumigatus was found in 5.3% of all A. fumigatus isolates. Three isolates presented the TR34/L98H mutation of the cyp51A gene. Patients with invasive aspergillosis caused by azole-resistant A. fumigatus showed 100% all-cause mortality at 100 days. This study demonstrates the significant portion of cryptic Aspergillus species and clinical implications of azole resistance and underscores the comparison between clinical and environmental isolates.

TR34/L98H Mutation in CYP51A Gene in Aspergillus fumigatus Clinical Isolates During Posaconazole Prophylaxis: First Case in Korea.

Azole resistance in Aspergillus fumigatus is an emerging problem, especially in immunocompromised patients. It has been reported worldwide, including in Asia, but has not yet been reported in Korea. Here, we report a case of invasive pulmonary aspergillosis (IPA) caused by azole-resistant A. fumigatus that developed in a hematopoietic stem cell transplantation recipient during posaconazole prophylaxis for immunosuppressive therapy of graft-versus-host diseases. We identified TR34/L98H/S297T/F495L mutation in the CYP51A gene of A. fumigatus clinical isolate obtained from bronchial washing fluid. Minimal inhibitory concentrations for itraconazole, voriconazole, and posaconazole were > 16, 1, and 4 µg/mL, respectively. While IPA improved partially under voriconazole treatment, the patient died from carbapenemase-producing Klebsiella pneumoniae bacteremia. Further epidemiological surveillance studies are warranted.

Establishment of Experimental Murine Peritonitis Model with Hog Gastric Mucin for Carbapenem-Resistant Gram-Negative Bacteria.

Animal models are essential to studies of infectious diseases. The use of mice to test bacterial infection has been extensively reported. However, methods applied to clinical isolates, particularly for carbapenem-resistant bacteria, must be tailored according to the infection models and bacteria used. In this study, we infected 6-week-old female BALB/c mice intraperitoneally with different strains of resistant bacteria plus 3% hog gastric mucin. This method was found to be efficient and readily applicable for investigation of carbapenem-resisant Gram-negative pathogens (e.g., Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii) detected in Korea.

Pilot Screening to Determine Antimicrobial Synergies in a Multidrug-Resistant Bacterial Strain Library.

With the rise in multidrug-resistant (MDR) bacterial infections, there has been increasing interest in combinations of ≥2 antimicrobial agents with synergistic effects. We established an MDR bacterial strain library to screen for in vitro antimicrobial synergy by using a broth microdilution checkerboard method and high-throughput luciferase-based bacterial cell viability assay. In total, 39 MDR bacterial strains, including 23 carbapenem-resistant gram-negative bacteria, 9 vancomycin-intermediate Staphylococcus aureus, and 7 vancomycin-resistant Enterococcus faecalis, were used to screen for potential antimicrobial synergies. Synergies were more frequently identified with combinations of imipenem plus trimethoprim-sulfamethoxazole for carbapenem-resistant Acinetobacter baumannii in the library. To verify this finding, we tested 34 A. baumannii clinical isolates resistant to both imipenem and trimethoprim-sulfamethoxazole by the checkerboard method. The imipenem plus trimethoprim-sulfamethoxazole combination showed synergy in the treatment of 21 (62%) of the clinical isolates. The results indicate that pilot screening for antimicrobial synergy in the MDR bacterial strain library could be valuable in the selection of combination therapeutic regimens to treat MDR bacterial infections. Further studies are warranted to determine whether this screening system can be useful to screen for the combined effects of conventional antimicrobials and new-generation antimicrobials or nonantimicrobials.

Stenotrophomonas maltophilia bloodstream infection in patients with hematologic malignancies: a retrospective study and in vitro activities of antimicrobial combinations.

BACKGROUND: Stenotrophomonas maltophilia causes serious infections in immunocompromised hosts. Here, we analyzed the clinical characteristics of S. maltophilia bloodstream infection (BSI) in patients with hematologic malignancies and evaluated in vitro synergistic effects of antimicrobial combinations. METHODS: We retrospectively reviewed all consecutive episodes of S. maltophilia BSIs in adult hematologic patients from June 2009 to May 2014, with in vitro susceptibility and synergy tests using high-throughput bioluminescence assay performed for available clinical isolates. RESULTS: Among 11,004 admissions during 5-year period, 31 cases were identified as S. maltophilia BSIs. The incidence rate of S. maltophilia BSI was 0.134 cases/1,000 patient-days. Overall and attributable mortality of S. maltophilia BSI was 64.5% and 38.7%, respectively. Severe neutropenia (adjusted hazard ratio [HR] 5.24, p =0.013), shock at the onset of BSI (adjusted HR 6.05, p <0.001), and pneumonia (adjusted HR 3.15, p =0.017) were independent risk factors for mortality. In vitro susceptibilities to ceftazidime, levofloxacin, ticarcillin-clavulanic acid (TIM) and trimethoprim-sulfamethoxazole (SXT) were 11.1%, 44.0%, 40.7%, and 88.9%, respectively. MIC50/MIC90 for moxifloxacin and tigecycline were 1/4 mg/L and 4/8 mg/L. The 50% and 90% fractional inhibitory concentrations (FIC(50)/FIC(90)) of clinical isolates against a combination of SXT and TIM were 0.500/0.750. For SXT plus levofloxacin or moxifloxacin, FIC(50)/FIC(90) were 0.625/1.000 and 0.625/0.625, respectively. CONCLUSION: S. maltophilia BSIs show high mortality, which is related to severe neutropenia, shock, and S. maltophilia pneumonia. Based upon drug susceptibility testing, the primary treatment of choice for S. maltophilia BSIs should be SXT in hematologic patients, rather than quinolones, with combination therapies including SXT serving as a feasible treatment option.

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.

Efficacies of vancomycin, arbekacin, and gentamicin alone or in combination against methicillin-resistant Staphylococcus aureus in an in vitro infective endocarditis model.

We adopted an in vitro infective endocarditis model (IVIEM) to compare the efficacy of vancomycin (VAN), arbekacin (ABK), and gentamicin (GEN) alone or in combination. Using two strains of clinically isolated methicillin-resistant Staphylococcus aureus, one GEN susceptible (GS171) and one GEN resistant (GR153), fibrin clots were prepared and suspended in the IVIEM. Antibiotics were given as boluses every 6 h (q6h), q12h, or q24h or by continuous infusion with VAN, q12h or q24h with ABK, and q8h or q24h with GEN. For combination treatment, VAN q12h plus ABK q24h and VAN q12h plus GEN q24h were given. Fibrin clots were removed from each model at 0, 8, 24, 32, 48, and 72 h, and the bacterial densities were determined. The number of colonies within the fibrin clot was significantly decreased in all study groups compared with control groups (P<0.001). When VAN and ABK were administered alone, the number of colonies was significantly lower in GS171 than in GR153 by 8 h after administration (P=0.02) and was lowest in GS171 when ABK was administered q12h (P=0.01). At 72 h, ABK or VAN alone produced equivalent bacterial reductions regardless of dosing frequency and GEN resistance. In GR153, VAN plus ABK showed an additive effect till 24 h, although VAN plus GEN showed indifference. Our data suggest that ABK could be used as an alternative to VAN in GEN-resistant staphylococcal endocarditis. An additive effect was seen when VAN and ABK were used together in GEN-resistant strains until 24 h; however, further studies are warranted for the clinical application of this combination.