Jannik Helweg-Larsen

Dr. Jannik Helweg-Larsen


Research Focus & Metrics

Academic Career Length

11Years (2016-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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13 August 2020 in Frontiers in Microbiology
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Journal Article
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MRMalene Risum
Malene Risum
RHRasmus Krøger Hare
Rasmus Krøger Hare
JGJan Berg Gertsen
Jan Berg Gertsen
LKLise Kristensen
Lise Kristensen
HJHelle Krogh Johansen
Helle Krogh Johansen
Maiken ArendrupMaiken Arendrup
Maiken Arendrup
Azole-resistant (azole-R) Aspergillus is an increasing challenge worldwide. Patients with cystic fibrosis (CF) are at risk of Aspergillus colonization and disease due to a favorable lung environment for microorganisms. We performed a nationwide study in 2018 of azole-non-susceptible Aspergillus in CF patients and compared with data from two prior studies. All airway samples with mold isolates from patients monitored at the two CF centers in Denmark (RH, Jan–Sept and AUH, Jan–Jun) were included. Classical species identification (morphology and thermo-tolerance) was performed and MALDI-TOF/β-tubulin sequencing was performed if needed. Susceptibility was determined using EUCAST E.Def 10.1, and E.Def 9.3.2. cyp51A sequencing and STRAf genotyping were performed for azole-non-susceptible isolates and relevant sequential isolates. In total, 340 mold isolates from 159 CF patients were obtained. The most frequent species were Aspergillus fumigatus (266/340, 78.2%) and Aspergillus terreus (26/340, 7.6%). Azole-R A. fumigatus was cultured from 7.3% (10/137) of patients, including 9.5% (9/95) of patients at RH and 2.4% at AUH (1/42), respectively. In a 10-year perspective, azole-non-susceptibility increased numerically among patients at RH (10.5% in 2018 vs 4.5% in 2007–2009). Cyp51A resistance mechanisms were found in nine azole-R A. fumigatus from eight CF patients. Five were of environmental origin (TR34/L98H), three were human medicine-driven (two M220K and one M220R), and one was novel (TR343/L98H) and found in a patient who also harbored a TR34/L98H isolate. STRAf genotyping identified 27 unique genotypes among 45 isolates and ≥2 genotypes in 8 of 12 patients. This included one patient carrying two unique TR34/L98H isolates, a rare phenomenon. Genotyping of sequential TR343/L98H and TR34/L98H isolates from the same patient showed only minor differences in 1/9 markers. Finally, azole-R A. terreus was found in three patients including two with Cyp51A alterations (M217I and G51A, respectively). Azole-R A. fumigatus is increasing among CF patients in Denmark with the environmentally associated resistance TR34/L98H mechanism being dominant. Mixed infections (wildtype/non-wildtype and several non-wildtypes) and a case of potential additional tandem repeat acquisition in vivo were found. However, similar genotypes were identified from another patient (and outside this study), potentially suggesting a predominant TR34/L98H clone in DK. These findings suggest an increasing prevalence and complexity of azole resistance in A. fumigatus.

28 February 2018 in Infectious Diseases
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KBKristian Buch-Larsen
Kristian Buch-Larsen
JBJacob Bodilsen
Jacob Bodilsen
AKAndreas Knudsen
Andreas Knudsen
LLLykke Larsen
Lykke Larsen
JHJannik Helweg-Larsen
Jannik Helweg-Larsen
FBfor the Danish Study Group for Infections in the Brain
for the Danish Study Group for Infections in the Brain
The ability of cerebrospinal fluid (CSF) lactate to distinguish between acute bacterial meningitis (ABM) and aseptic meningitis/encephalitis (AME) is debated. We assessed the diagnostic value of CSF lactate to discriminate between ABM and AME. We included 176 patients from a prospective adult cohort with neuroinfections. In total, 51 ABM and 125 AME patients with clinically and/or microbiologically diagnosed acute meningitis were examined with CSF-lactate and traditional markers for infection. Receiver operating characteristic (ROC) curves were used to assess diagnostic performance. In CSF, lactate, leukocytes, fraction of neutrophils, protein and glucose ratio, were significantly different between the ABM and AME groups. CSF lactate had the best diagnostic value, with an area under the curve (AUC) of 0.976 (95%CI 0.966-0.997) and using a cut-off of 3.5 mmol/L a sensitivity of 96% and specificity of 85%. Antibiotic treatment before lumbar puncture had no significant effect on the AUC of CSF lactate. Compared to traditional CSF-markers, CSF lactate is more accurate to distinguish between ABM and AME.

28 October 2025 in Circulation
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Journal Article
Open access
PGPeter Laursen Graversen
Peter Laursen Graversen
LØLauge Østergaard
Lauge Østergaard
KHKatra Hadji-Turdeghal
Katra Hadji-Turdeghal
JMJacob Eifer Møller
Jacob Eifer Møller
NBNiels Eske Eske Bruun
Niels Eske Eske Bruun
EFEmil Loldrup Fosbøl
Emil Loldrup Fosbøl
BACKGROUND: Surgery is an essential treatment for selected patients with infective endocarditis (IE). Despite indications for surgery, not all patients undergo surgery. Most previous IE cohorts have examined a selected group of patients from primary tertiary centers. Thus, the aims of this study were to describe the use of surgery by indication and to assess mortality in a nationwide cohort of patients with left-sided IE. METHODS: This study was an observational cohort study including patients with left-sided IE from the National Danish Endocarditis Studies (2016-2021). Patients were categorized according to the presence of surgical indications defined as a Class I indication for surgery according to the 2015 European guidelines or a vegetation ≥10 mm on the diagnostic echocardiography and whether surgery was performed. One-year mortality was assessed with the 1-Kaplan-Meier estimator and multivariable Cox regression models. RESULTS: Among 3017 patients, 662 (21.9%; median age, 66.9 years) underwent surgery, 655 (21.6%; median age, 75.9 years) had surgical indications but received conservative treatment, and 1700 (56.5%; median age, 76.0 years) had no surgical indications. Patients who underwent surgery had fewer comorbidities and more streptococci, whereas conservatively treated patients had more comorbidities and Staphylococcus aureus . Patients with surgical indications who did not undergo surgery had the highest in-hospital (31.8% versus 12.5% versus 15.7%; P <0.001) and 1-year (50.5% versus 17.0% versus 33.5%, P <0.001) mortality compared with patients who underwent surgery and those without indications for surgery. Multivariable Cox models confirmed these findings. High surgical risk (22.8%) was the most reported reason for withholding surgery. CONCLUSIONS: In a nationwide consecutive cohort of patients with left-sided IE, 40% had indications for surgery according to guidelines, but only half of these underwent surgery. Surgically treated patients had the highest survival but were a decade younger, had fewer comorbidities, and had less frequent IE caused by S aureus. Thus, confounding by indication remains a limitation, and more studies are warranted to explore the management of patients at high surgical risk.

8 November 2020 in Journal of Fungi
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Journal Article
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MRMalene Risum
Malene Risum
JHJannik Helweg-Larsen
Jannik Helweg-Larsen
SPSøren Lykke Petersen
Søren Lykke Petersen
PKPeter Kampmann
Peter Kampmann
UOUlrik Malthe Overgaard
Ulrik Malthe Overgaard
Maiken ArendrupMaiken Arendrup
Maiken Arendrup
Mucormycosis is a life threatening infection in patients with haematological disease. We introduced a Mucorales-PCR and an aggressive, multidisciplinary management approach for mucormycosis during 2016–2017 and evaluated patient outcomes in 13 patients diagnosed and treated in 2012–2019. Management principle: repeated surgical debridement until biopsies from the resection margins were clean as defined by negative Blankophor microscopy, Mucorales-PCR (both reported within 24 h), and cultures. Cultured isolates underwent EUCAST E.Def 9.3.1 susceptibility testing. Antifungal therapy (AFT) (mono/combination) combined with topical AFT (when possible) was given according to the minimal inhibitory concentration (MIC), severity of the infection, and for azoles, specifically, it was guided by therapeutic drug monitoring. The outcome was evaluated by case record review. All patients underwent surgery guided by diagnostic biopsies from tissue and resection margins (195 samples in total). Comparing 2012–2015 and 2016–2019, the median number of patients of surgical debridements was 3 and 2.5 and of diagnostic samples: microscopy/culture/PCR was 3/3/6 and 10.5/10/10.5, respectively. The sensitivity of microscopy (76%) and Mucorales-PCR (70%) were similar and microscopy was superior to that of culture (53%; p = 0.039). Initial systemic AFT was liposomal amphotericin B (n = 12) or posaconazole (n = 1) given as monotherapy (n = 4) or in combination with isavuconazole/posaconazole (n = 3/6) and terbinafine (n = 3). Nine patients received topical amphotericin B. All received isavuconazole or posaconazole consolidation therapy (n = 13). Mucormycosis related six month mortality was 3/5 in 2012–2015 and 0/7 patients in 2016–2019 (one patient was lost for follow-up). Implementation of combination therapy (systemic+topical AFT/combination systemic AFT) and aggressive surgical debridement guided by optimised diagnostic tests may improve the outcome of mucormycosis in haematologic patients.

1 March 2020 in Medical Mycology Case Reports
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Journal Article
Open access
MGMariam Gheshlaghi
Mariam Gheshlaghi
JHJannik Helweg-Larsen
Jannik Helweg-Larsen
We report a case of fatal chronic Candida dubliniensis meningitis complicated by severe hydrocephalus secondary to liver transplantation, in which diagnosis was considerably delayed.

3 April 2020 in medRxiv
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OHOliver James Hulme
Oliver James Hulme
EWEric-Jan Wagenmakers
Eric-Jan Wagenmakers
PDPer Damkier
Per Damkier
CMChristopher Fugl Madelung
Christopher Fugl Madelung
HSHartwig Roman Siebner
Hartwig Roman Siebner
KMKristoffer Hougaard Madsen
Kristoffer Hougaard Madsen
Gautret and colleagues reported results of a non-randomised open-label case series which examined the effects of hydroxychloroquine and azithromycin on viral load in the upper respiratory tract of Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) patients. The authors report that hydroxychloroquine (HCQ) had significant virus reducing effects, and that dual treatment of both HCQ and azithromycin further enhanced virus reduction. These data have triggered speculation whether these drugs should be considered as candidates for the treatment of severe COVID-19. However, questions have been raised regarding the study’s data integrity, statistical analyses, and experimental design. We therefore reanalysed the original data to interrogate the main claims of the paper. Here we apply Bayesian statistics to assess the robustness of the original paper’s claims by testing four variants of the data: 1) The original data; 2) Data including patients who deteriorated; 3) Data including patients who deteriorated with exclusion of untested patients in the comparison group; 4) Data that includes patients who deteriorated with the assumption that untested patients were negative. To ask if HCQ monotherapy is effective, we performed an A/B test for a model which assumes a positive effect, compared to a model of no effect. We find that the statistical evidence is highly sensitive to these data variants. Statistical evidence for the positive effect model ranged from strong for the original data (BF +0 ∼11), to moderate when including patients who deteriorated (BF +0 ∼4.35), to anecdotal when excluding untested patients (BF +0 ∼2), and to anecdotal negative evidence if untested patients were assumed positive (BF +0 ∼0.6). To assess whether HCQ is more effective when combined with AZ, we performed the same tests, and found only anecdotal evidence for the positive effect model for the original data (BF +0 ∼2.8), and moderate evidence for all other variants of the data (BF +0 ∼5.6). Our analyses only explore the effects of different assumptions about excluded and untested patients. These assumptions are not adequately reported, nor are they justified in the original paper, and we find that varying them causes substantive changes to the evidential support for the main claims of the original paper. This statistical uncertainty is exacerbated by the fact that the treatments were not randomised, and subject to several confounding variables including the patients consent to treatment, different care centres, and clinical decision-making. Furthermore, while the viral load measurements were noisy, showing multiple reversals between test outcomes, there is greater certainty around other clinical outcomes such as the 4 patients who seriously deteriorated. The fact that all of these belonged to the HCQ group should be assigned greater weight when evaluating the potential clinical efficacy of HCQ. Randomised controlled trials are currently underway, and will be critical in resolving this uncertainty as to whether HCQ and AZ are effective as a treatment for COVID-19. Warning: There have been reports of people self-administering chloroquine phosphate (intended for treatment of disease in aquarium fish), which has led to at least one death and one serious illness. We state that under no circumstances should people self-administer hydroxychloroquine, chloroquine phosphate, azithromycin, or anything similar-sounding, or indeed any other drug, unless approved by a medical doctor. The FDA has issued a specific warning: https://www.fda.gov/animal-veterinary/product-safety-information/fda-letter-stakeholders-do-not-use-chloroquine-phosphate-intended-fish-treatment-covid-19-humans