KMKlaus Leth Mortensen

Klaus Leth Mortensen

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Previous Organizations / Institutes

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Klaus Leth Mortensen has a total of 81 co-authors. Here are the top co-authors by number of shared publications:


Latest Publications

  • Pediatric Candidemia Epidemiology and Morbidities

    by Karen Rokkedal Lausch, Kia Hee Schultz Dungu, Michael Thude Callesen, Steen Rosthøj, Anja Poulsen, Lars Østergaard, Klaus Leth Mortensen, Merete Storgaard, Henrik Carl Schønheyder, Mette Søgaard, et al.

    Background: Candidemia is the most frequent pediatric fungal infection, but incompletely elucidated in population-based settings. We performed a nationwide cohort study including all pediatric patients with candidemia in Denmark from 2004 to 2014 to determine age, incidence, species distribution, underlying diseases, patient management and outcomes. Methods: All candidemia episodes were identified through the active nationwide fungemia surveillance program. Susceptibility testing followed the EUCAST E.Def 7 (European Committee on Antifungal Susceptibility Testing, Edition Definitive) reference method. χ2 test, Fisher exact test and Venn diagrams were used for statistical analyses. Results: One hundred fifty-three pediatric patients (≤ 15 years) with 158 candidemia episodes were identified. The overall annual incidence rate was 1.3/100,000 population, higher for neonates (5.7/100,000 live births) and low birth weight neonates (103.8/100,000 live births). From 2004 to 2009 to 2010 to 2014, the proportion of Candida albicans decreased from 74.4% to 64.7%, whereas fluconazole resistance increased from 7.8% to 17.7%. Virtually all patients had at least 1 underlying disease (98.6%) and multimorbidity was common (43.5%, ≥2 underlying diseases). Underlying diseases differed by age with heart malformations and gastrointestinal disease prevalent in children younger than 3 years. The overall 30-days mortality was 10.2% and highest for neonates (17.1%). Mortality increased from 2004 to 2010 to 2014, driven by an increase among older children. Conclusion: This first nationwide epidemiologic study of pediatric candidemia confirmed a high incidence among neonates and a substantial burden of comorbidities. Moreover, an increasing proportion of fluconazole resistant nonalbicans species was observed. Our findings underline the importance of choosing correct treatment and continuous surveillance of pediatric candidemia.


  • Open Access

    Treatment of candidemia in a nationwide setting: increased survival with primary echinocandin treatment

    by Karen Rokkedal Lausch, Mette Søgaard, Flemming Schønning Rosenvinge, Helle Krogh Johansen, Trine Boysen, Bent Løwe Røder, Klaus Leth Mortensen, Lene Nielsen, Lars Lemming, Bente Olesen, et al.

    Background: In accordance with international guidelines, primary antifungal treatment (AFT) of candidemia with echinocandins has been nationally recommended in Denmark since 2009. Our nationwide cohort study describes the management of candidemia treatment focusing on the impact of prophylactic AFT on species distribution, the rate of adherence to the recommended national guidelines for AFT, and the effect of AFT on patient outcomes. Materials and methods: Incident candidemia cases from a 2-year period, 2010–2011, were included. Information on AFT was retrospectively collected from patient charts. Vital status was obtained from the Danish Civil Registration System. HRs of mortality were reported with 95% CIs using Cox regression. Results: A total of 841 candidemia patients was identified. Prior to candidemia diagnosis, 19.3% of patients received AFT (162/841). The risk of non-albicans candidemia increased after prior AFT (59.3% vs 45.5% among nontreated). Echinocandins as primary AFT were given for 44.2% (302/683) of patients. Primary treatment with echinocandins resulted in adequate treatment in a higher proportion of patients (97.7% vs 72.1%) and was associated with lower 0- to 14-day mortality compared with azole treatment (adj. HR 0.76, 95% CI: 0.55–1.06). Significantly lower 0- to 14-day mortality was observed for patients with Candida glabrata and Candida krusei with echinocandin treatment compared with azole treatment (adj. HR 0.50, 95% CI: 0.28–0.89), but not for patients with Candida albicans or Candida tropicalis. Conclusion: The association shown between prior AFT and non-albicans species underlines the importance of treatment history when selecting treatment for candidemia. Compliance with national recommendations was low, but similar to previously reported international rates. Primary treatment of candidemia with echinocandins compared with azoles yielded both a higher proportion of adequately treated patients and improved mortality rates. This real-life setting supports guidelines recommendation, and further focus on compliance with these seems warranted.


  • Open Access

    High incidence of candidaemia in a nationwide cohort: Underlying diseases, risk factors and mortality

    by K.R. Lausch, M. Søgaard, F.S. Rosenvinge, H.K. Johansen, T. Boysen, B. Røder, K.L. Mortensen, L. Nielsen, L. Lemming, B. Olesen, et al.


  • Spectrophotometric reading of EUCAST antifungal susceptibility testing of Aspergillus fumigatus

    by J. Meletiadis, K. Leth Mortensen, P.E. Verweij, J.W. Mouton, M.C. Arendrup


  • Severe acute pancytopaenia in a patient with rheumatoid arthritis complicated by fatal invasive pulmonary aspergillosis

    by Kl Mortensen, Tp Krogh, S Jensen-Fangel, Em Hauge

    (2017). Severe acute pancytopaenia in a patient with rheumatoid arthritis complicated by fatal invasive pulmonary aspergillosis. Scandinavian Journal of Rheumatology: Vol. 46, No. 3, pp. 249-250.


  • The burden of fungal disease in Denmark

    by Klaus L. Mortensen, David W. Denning, Maiken C. Arendrup

    Summary: The aim of this study is to calculate the burden of fungal disease in Denmark. We identified all published epidemiology papers reporting fungal infection rates in Denmark. Where no data existed, we used numbers of specific populations at risk and fungal infection frequencies in those populations to estimate national incidence or prevalence. Approximately, one in six Danes will suffer from a fungal infection each year, most of which are skin or mucosal diseases causing disability but no deaths. Good data exist on candidaemia where a national voluntary reporting system is in place and have shown a high rate (9.6 per 100 000 inhabitants) compared other European countries. We present estimates of invasive aspergillosis and chronic pulmonary aspergillosis with rates of 4.4 per 100 000 and 3.1 per 100 000 inhabitants, respectively. Further studies are needed in order to better ascertain high‐burden fungal infections such as recurrent vulvovaginal candidiasis (~1350 cases in 100 000 women) as well as allergic bronchopulmonary aspergillosis (~131 cases in 100 000 inhabitants) and severe asthma with fungal sensitisation (cases in 100 000 inhabitants). In conclusion, more than 93 000 Danes or about 2% of Denmark's population will have a non‐trivial fungal infection during 1 year, which underscores the magnitude of the fungal burden.


  • Open Access

    Fungal Keratitis - Improving Diagnostics by Confocal Microscopy

    by Esben Nielsen, Steffen Heegaard, Jan Ulrik Prause, Anders Ivarsen, Klaus Leth Mortensen, Jesper Hjortdal

    Purpose: Introducing a simple image grading system to support the interpretation of in vivo confocal microscopy (IVCM) images in filamentous fungal keratitis. Setting: Clinical and confocal studies took place at the Department of Ophthalmology, Aarhus University Hospital, Denmark. Histopathological analysis was performed at the Eye Pathology Institute, Department of Neuroscience and Pharmacology, University of Copenhagen, Denmark. Methods: A recent series of consecutive patients with filamentous fungal keratitis is presented to demonstrate the results from in-house IVCM. Based upon our experience with IVCM and previously published images, we composed a grading system for interpreting IVCM images of filamentous fungal keratitis. Results: A recent case series of filamentous fungal keratitis from 2011 to 2012 was examined. There were 3 male and 3 female patients. Mean age was 44.5 years (range 12-69), 6 out of 17 (35%) cultures were positive and a total of 6/7 (86%) IVCM scans were positive. Three different categories of IVCM results for the grading of diagnostic certainty were formed. Conclusion: IVCM is a valuable tool for diagnosing filamentous fungal keratitis. In order to improve the reliability of IVCM, we suggest implementing a simple and clinically applicable grading system for aiding the interpretation of IVCM images of filamentous fungal keratitis.


  • Aspergillus Species and Other Molds in Respiratory Samples from Patients with Cystic Fibrosis: a Laboratory-Based Study with Focus on Aspergillus fumigatus Azole Resistance

    by Klaus Leth Mortensen, Rasmus Hare Jensen, Helle Krogh Johansen, Marianne Skov, Tacjana Pressler, Susan Julie Howard, Howard Leatherbarrow, Emilia Mellado, Maiken Cavling Arendrup

    Respiratory tract colonization by molds in patients with cystic fibrosis (CF) were analyzed, with particular focus on the frequency, genotype, and underlying mechanism of azole resistance among Aspergillus fumigatus isolates. Clinical and demographic data were also analyzed. A total of 3,336 respiratory samples from 287 CF patients were collected during two 6-month periods in 2007 and 2009. Azole resistance was detected using an itraconazole screening agar (4 mg/liter) and the EUCAST method. cyp51A gene sequencing and microsatellite genotyping were performed for isolates from patients harboring azole-resistant A. fumigatus. Aspergillus spp. were present in 145 patients (51%), of whom 63 (22%) were persistently colonized. Twelve patients (4%) harbored other molds. Persistently colonized patients were older, provided more samples, and more often had a chronic bacterial infection. Six of 133 patients (4.5%) harbored azole-nonsusceptible or -resistant A. fumigatus isolates, and five of those six patients had isolates with Cyp51A alterations (M220K, tandem repeat [TR]/L98H, TR/L98H-S297T-F495I, M220I-V101F, and Y431C). All six patients were previously exposed to azoles. Genotyping revealed (i) microevolution for A. fumigatus isolates received consecutively over the 2-year period, (ii) susceptible and resistant isolates (not involving TR/L98H isolates) with identical or very closely related genotypes (two patients), and (iii) two related susceptible isolates and a third unrelated resistant isolate with a unique genotype and the TR/L98H resistance combination (one patient). Aspergilli were frequently found in Danish CF patients, with 4.5% of the A. fumigatus isolates being azole nonsusceptible or resistant. Genotyping suggested selection of resistance in the patient as well as resistance being achieved in the environment.