A. Nedret Koc

Does ampicillin-sulbactam cause false positivity of (1,3)-beta-D-glucan assay? A prospective evaluation of 15 patients without invasive fungal infections*

The purpose of this study was to investigate the interaction between intravenous ampicillin‐sulbactam treatment and (1,3)‐beta‐D‐glucan (BDG) assay. Fifteen patients with a median age of 60 (16–81) without known risk factors for invasive fungal infections who received a daily dose of 3 × 2 g ampicillin‐sulbactam monotherapy from different batches were included in the study. Thirteen patients had soft tissue infections. The 5 of 13 patients who went under surgery had surgical dressings. Serum samples were obtained both before and after antibiotic infusion on the first, third, seventh and tenth days of an ampicillin‐sulbactam treatment course. BDG was assayed using the Fungitell kit (Associates of Cape Cod, East Falmouth, MA, USA) according to manufacturers’ specifications. All serum samples were also tested for galactomannan (GM) antigenemia by Platelia Aspergillus ELISA (Bio‐Rad Laboratories, Marnes‐la‐Coquette, France). A total of 37 of 117 serum samples were positive for BDG at a threshold of 80 pg ml−1. Seven of 37 BDG positive serum samples had a GM index ≥0.5. When a cutoff value of ≥0.5 was used for GM positivity, 16 (13.3%) serum samples were positive. For a cutoff value of ≥0.7, eight (6.6%) serum samples were positive. There were no statistically significant differences in the median BDG levels (P = 0.47) or median GM indices (P = 0.28) of the various sampling times. None of the SAM vials tested positive for BDG or GM. After ruling out fungal infections and all known potential causes of false BDG positivity, environmental contamination remained possible cause of BDG reactivity. We did not observe any significant association of ampicillin‐sulbactam administration and positive assays for BDG or GM.

Outbreak of nosocomial fungemia caused by Candida glabrata

Summary.  An outbreak of Candida glabrata fungemia that was thought to be associated with bottles used for milk feeds occurred at our childrens infectious diseases clinic. This cluster of cases was investigated using a case–control study. Isolates were identified by conventional methods and karyotyped using pulsed‐field gel electrophoresis (PFGE) of genomic DNA. Potential risk factors for nine hospitalized children with candidemia and 14 controls were long‐term hospitalization and treatments with more than two antibiotics. Electrophoretic karyotyping showed a single chromosomal pattern for these outbreak isolates and, in addition, they all had the same antifungal susceptibility results. These findings suggest that clonal dissemination of a single strain was responsible for this outbreak. Karyotyping by PFGE appears to be a useful molecular typing method for strains of C. glabrata.

What should be the optimal cut-off of serum 1,3-β-d-glucan for the detection of invasive pulmonary aspergillosis in patients with haematological malignancies?

Abstract Background: The detection of 1,3-β-d-glucan (BDG), a cell wall component of several medically important fungi, is a promising tool for the diagnosis of invasive pulmonary aspergillosis. The aim of this study was to evaluate the diagnostic accuracy of the BDG test in invasive pulmonary aspergillosis (IPA) by focusing on the optimal cut-off value. Methods: The records of the Infection Control Committee were reviewed to identify patients with haematological malignancies and stem cell transplantation who had at least 1 BDG (Fungitell kit) measurement during the period January 2008 through April 2011. The European Organization for Research and Treatment of Cancer and the Mycoses Study Group (EORTC/MSG) criteria (independent of BDG results) were used to categorize the patients with IPA. Patients with possible IPA were not included in the study. Results: A total of 128 patients (50 with proven or probable IPA) were included in the study. At the manufacturers recommended cut-off value of 80 pg/ml, the sensitivity of BDG was 66% (95% CI 51.2–78.7), specificity 75.6% (95% CI 64.6–84.5), positive predictive value (PPV) 63.4%, and negative predictive value (NPV) 77.6%. A receiver operating characteristic (ROC) curve was constructed to define the optimum serum BDG cut-off for the diagnosis of IPA. At a cut-off value of 181 pg/ml, the sensitivity was 52% (95% CI 37.4–66.3), specificity 94.8% (95% CI 87.4–98.6), PPV 86.7%, and NPV 75.5%. Conclusions: Although higher cut-off levels increased the specificity of the BDG test, sensitivity decreased to an unacceptable level; the commercially recommended cut-off value appears to be appropriate for screening purposes.

Case reports. Trichosporon mucoides infection in three premature newborns.

Summary. In the present study Trichosporon mucoides infections in 3 premature newborns are reported.

Case Report. Acremonium falciforme fungemia in a patient with acute leukaemia

Summary.  We describe a case of Acremonium falciforme fungemia under treatment of fluconazole. A. falciforme is a common saprophyte. This fungus has been isolated from a patients specimen, and the organism may have contributed to his death.

Comparison of Etest with the broth microdilution method in susceptibility testing of yeast isolates against four antifungals

A comparative evaluation of the Etest and the broth microdilution methods for antifungal susceptibility testing of 102 clinical yeast isolates against amphotericin B, fluconazole, itraconazole, and ketoconazole was conducted. The agreements between the Etest and the broth microdilution methods were 93.1% for amphotericin B 85.2% for ketoconazole, 82.3% for itraconazole and 79.4% for fluconazole. These results suggest that the Etest approach to antifungal susceptibility testing may be a viable alternative to the NCCLS reference methods for testing yeasts, but that further evaluations are needed.

Antifungal susceptibility testing of Candida albicans by flow cytometry.

Antifungal susceptibilities of 28 Candida albicans isolates and two quality control strains to amphotericin B and fluconazole were determined by flow cytometry and microdilution method. Minimum inhibitory concentrations (MICs) obtained by flow cytometry were compared with the results obtained by The National Committee for Clinical Laboratory Standards Subcommittee (NCCLS) broth microdilution method. The agreement of results (within two dilution) obtained was found as 96 and 93% for amphotericin B and fluconazole, respectively. At least 24 h incubation was required for reading the microdilution assays. Four hours of incubation was required for fluconazole, whereas 2‐h incubation was sufficient for amphotericin B to provide MIC by flow cytometry. Results of this study show that flow cytometry provides a rapid and sensitive in vitro method for antifungal susceptibility testing of Candida albicans isolates.

Molecular epidemiology and antifungal susceptibility of Saprochaete capitata (Blastoschizomyces capitatus) isolates causing nosocomial infection in Kayseri/Turkey

Abstract Background: Saprochaete capitata isolates have emerged as important nosocomial pathogens, among immunosuppressed or neutropenic patients, and a rare cause of nosocomial infection in the hematology–bone marrow unit (HBMU) and the intensive care unit (ICU). The purpose of this study was to molecular epidemiology and antifungal susceptibility of S. capitata (Blastoschizomyces capitatus) isolates causing nosocomial infection at Kayseri in Turkey. Methods: During a period from 2012 to 2015, a total of 20 S. capitata strains were obtained from patients hospitalized at Erciyes University Hospital. The identification of S. capitata was performed by phenotypic and biochemical methods; this was confirmed by molecular methods by DNA sequencing analysis. Genotyping of S.capitata isolates from different patients was determined to by the repetitive sequence PCR (repPCR) using the DiversiLab System (BioMerieux). Results: More than half of the patients with S. capitata infections were hospitalized in the hematology–oncology unit (60%). The patients mainly included those using intravascular devices (90%), and receiving parenteral antibiotics (85%); the mortality rate was 55%. The microbiological investigation failed to identify S. capitata in the hospital environment. All isolates were resistant to caspofungin (>32). However, the MIC90 values for voriconazole, amphotericin B, and fluconazole against all of the isolates were 0.125, 0.25, and 1μg/ml, respectively. The S. capitata strains belonged to five clones (A–E) which were determined by the use of rep-PCR and Clone C was found to be predominant. Conclusions: S. capitata isolates are an important cause of nosocomial infection in the HBMU and ICUs.

Case Report. Candida lusitaniae peritonitis in a patient on continuous ambulatory peritoneal dialysis

Summary. We report a case of Candida lusitania peritonitis in continuous ambulatory peritoneal dialysis. Since fluconazole therapy was not successful in this patient, the peritoneal catheter was removed and antifungal therapy continued, and the patient was then converted to haemodialysis. This treatment protocol was successful. We suggest that early peritoneal catheter removal should be considered in such cases.

Interdigital foot infections: Corynebacterium minutissimum and agents of superficial mycoses

Interdigital foot infections are mostly caused initially by dermatophytes, yeasts and less frequently by bacteria. Erythrasma caused by Corynebacterium minutissimum can be confused with superficial mycoses. The aim of the study was to determine the prevalence of the etiologic agents of superficial mycoses and the frequency of Corynebacterium minutissimum in interdigital foot infections. All the samples obtained from the 121 patients with interdigital foot infections were examined directly with the use of 20% potassium hydroxide mounts and Gram stain under the microscope and cultured on Sabouraud’s dextrose agar plates. In identification of superficial mycoses, the rate was found to be 14% with the cultural method and 14% with direct microscopic examination. Using a combination of direct microscopic examination and culture, a 33.8% ratio was achieved. In the culture of these samples, the most isolated factor was Trichophyton rubrum (33.7%). In 24 of the patients (19.8%) Corynebacterium minutissimum was detected by Gram staining, in 6 of these patients Trichophyton rubrum was found, Trichophyton mentagrophytes was found in 2 and Trichosporon spp. was found in 1. The examination of interdigital foot lesions in the laboratory, the coexistence of erythrasma with dermatophytes and yeast should be considered.