ISO standard 20776-1 or serial 2-fold dilution for antifungal susceptibility plate preparation: that is the question!

BACKGROUND: Since the ISO standard 20776-1 and serial dilution procedures were compared in 2010 for fluconazole and itraconazole, several new antifungals that are hydrophobic and highly potent have been introduced. OBJECTIVES: To investigate the impact of the number of tip changes during serial dilution, and ISO and serial dilution for nine antifungals. METHODS: EUCAST E.Def 7.3.2 with serial (0-10 tip changes) and ISO dilution. Candida parapsilosis ATCC 22019, Candida albicans ATCC 64548, C. albicans CNM CL-F8555, Candida krusei ATCC 6258, Aspergillus flavus ATCC 204304 and clinical isolates (n = 5) of C. albicans, Candida dubliniensis, Candida glabrata, C. krusei, A. flavus and Aspergillus terreus were included. GM MICs were compared for ISO and serial dilution and with QC values where available. RESULTS: Increasing the number of tip changes (0/1/2/10 times) during serial dilution for plate preparation increased the MICs 1 to >2 dilutions for amphotericin B, anidulafungin, micafungin, fluconazole, voriconazole and isavuconazole against C. albicans ATCC 64548 but only isavuconazole MICs against C. parapsilosis ATCC 22019 (3 dilutions). ISO and serial dilution (two tip changes) were compared for eight compounds and four Candida QC strains (352 MICs). Six/41 GM MIC pairs deviated with 1-1.8 dilution (14.6%). Comparing the GM MIC with the QC values, the ISO method GM MIC was closest to the target in 30.8%, the serial dilution in 34.6% and the methods identical in 34.6% of the cases. Finally, ISO and serial dilution MICs were compared for clinical isolates (920 MICs). Five/23 GM MIC pairs (21.7%) deviated 1.0-1.1 dilutions. CONCLUSIONS: The ISO and serial dilution (two tip changes) method were in acceptable agreement and thus equally applicable for EUCAST testing.

Clinical management of liver cyst infections: an international, modified Delphi-based clinical decision framework.

Liver cyst infections often necessitate long-term hospital admission and are associated with considerable morbidity and mortality. We conducted a modified Delphi study to reach expert consensus for a clinical decision framework. The expert panel consisted of 24 medical specialists, including 12 hepatologists, from nine countries across Europe, North America, and Asia. The Delphi had three rounds. The first round (response rate 21/24 [88%]) was an online survey with questions constructed from literature review and expert opinion, in which experts were asked about their management preferences and rated possible management strategies for seven clinical scenarios. Experts also rated 14 clinical decision-making items for relevancy and defined treatment outcomes. During the second round (response rate 13/24 [54%]), items that did not reach consensus and newly suggested themes were discussed in an online panel meeting. In the third round (response rate 16/24 [67%]), experts voted on definitions and management strategies using an online survey based on previous answers. Consensus was predefined as a vote threshold of at least 75%. We identified five subclassifications of liver cyst infection according to cyst phenotypes and patient immune status and consensus on episode definitions (new, persistent, and recurrent) and criteria for treatment success or failure was reached. The experts agreed that fever and elevated C-reactive protein are pivotal decision-making items for initiating and evaluating the management of liver cyst infections. Consensus was reached on 26 management statements for patients with liver cyst infections across multiple clinical scenarios, including two treatment algorithms, which were merged into one after comments. We provide a clinical decision framework for physicians managing patients with liver cyst infections. This framework will facilitate uniformity in the management of liver cyst infections and can constitute the basis for the development of future guidelines.

Monotherapy: Key cause of macrolide-resistant Mycobacterium avium complex disease.

BACKGROUND: Macrolide-resistant Mycobacterium avium complex (MAC) disease is very difficult to cure. Macrolide-resistance emerges in patients and is largely preventable by appropriate screening and treatment practices. METHODS: Patients with macrolide-resistant MAC isolates between March 2019 and March 2022 were retrieved from the mycobacteriology reference laboratory database at Radboudumc, Nijmegen, the Netherlands. Clinical consultation reports were extracted from the database to assess the cause of macrolide resistance. RESULTS: Sixteen patients with macrolide-resistant MAC disease were included, from a total of 815 patients with MAC isolates (2%); Macrolide monotherapy in bronchiectasis or CF was the most frequent cause of development of macrolide-resistance MAC disease (n = 8; 50%). Short (n = 3; mean duration 9 months, range 6-12) or guideline non-compliant (n = 2) treatment regimens and patient non-adherence (n = 2) were other key causes of macrolide-resistance. CONCLUSIONS: Macrolide monotherapy after inappropriate screening is the most frequent cause of macrolide-resistant Mycobacterium avium complex disease in the Netherlands. Educational efforts are needed to prevent this.

Chlorhexidine for the Treatment of Fusarium Keratitis: A Case Series and Mini Review.

Fungal keratitis is difficult to treat, especially Fusarium keratitis. In vitro studies show that chlorhexidine could be an interesting option as monotherapy. We describe a case series of four patients (four eyes) with Fusarium keratitis at Radboud University Medical Center (Nijmegen, the Netherlands). The patients were treated with chlorhexidine 0.02% eye drops. The in vitro activity of eight antifungals and chlorhexidine was determined according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) broth microdilution method. We also reviewed the literature on the use of chlorhexidine in the treatment of fungal keratitis. Topical chlorhexidine was well tolerated, and all patients showed complete resolution of the keratitis upon treatment with chlorhexidine. A PubMed search of the available literature was conducted (last search 8 March 2020) and yielded two randomized clinical trials (natamycin versus chlorhexidine) and one case report addressing the treatment of fungal keratitis with chlorhexidine. Chlorhexidine was found to be safe with regard to toxicity and to be superior to natamycin in the clinical trials. Chlorhexidine showed in vitro fungicidal activity against Fusarium and clinical effectiveness in our cases, supporting further clinical evaluation. Advantages of chlorhexidine are its topical application, its general availability, its low costs, its broad-spectrum activity, and its fungicidal mechanism of action at low concentrations.

Practical guidelines for interpreting copy number gains detected by high-resolution array in routine diagnostics.

The correct interpretation of copy number gains in patients with developmental delay and multiple congenital anomalies is hampered by the large number of copy number variations (CNVs) encountered in healthy individuals. The variable phenotype associated with copy number gains makes interpretation even more difficult. Literature shows that inheritence, size and presence in healthy individuals are commonly used to decide whether a certain copy number gain is pathogenic, but no general consensus has been established. We aimed to develop guidelines for interpreting gains detected by array analysis using array CGH data of 300 patients analysed with the 105K Agilent oligo array in a diagnostic setting. We evaluated the guidelines in a second, independent, cohort of 300 patients. In the first 300 patients 797 gains of four or more adjacent oligonucleotides were observed. Of these, 45.4% were de novo and 54.6% were familial. In total, 94.8% of all de novo gains and 87.1% of all familial gains were concluded to be benign CNVs. Clinically relevant gains ranged from 288 to 7912 kb in size, and were significantly larger than benign gains and gains of unknown clinical relevance (P < 0.001). Our study showed that a threshold of 200 kb is acceptable in a clinical setting, whereas heritability does not exclude a pathogenic nature of a gain. Evaluation of the guidelines in the second cohort of 300 patients revealed that the interpretation guidelines were clear, easy to follow and efficient.

Balanced into array: genome-wide array analysis in 54 patients with an apparently balanced de novo chromosome rearrangement and a meta-analysis.

High-resolution genome-wide array analysis enables detailed screening for cryptic and submicroscopic imbalances of microscopically balanced de novo rearrangements in patients with developmental delay and/or congenital abnormalities. In this report, we added the results of genome-wide array analysis in 54 patients to data on 117 patients from seven other studies. A chromosome imbalance was detected in 37% of all patients with two-breakpoint rearrangements. In 49% of these patients, the imbalances were located in one or both breakpoint regions. Imbalances were more frequently (90%) found in complex rearrangements, with the majority (81%) having deletions in the breakpoint regions. The size of our own cohort enabled us to relate the presence of an imbalance to the clinical features of the patients by using a scoring system, the De Vries criteria, that indicates the complexity of the phenotype. The median De Vries score was significantly higher (P=0.002) in those patients with an imbalance (5, range 1-9) than in patients with a normal array result (3, range 0-7). This study provides accurate percentages of cryptic imbalances that can be detected by genome-wide array analysis in simple and complex de novo microscopically balanced chromosome rearrangements and confirms that these imbalances are more likely to occur in patients with a complex phenotype.

A 649 kb microduplication in 1p34.1, including POMGNT1, in a patient with microcephaly, coloboma and laryngomalacia; and a review of the literature.

We report on a male patient with intra-uterine growth retardation, microcephaly, coloboma, laryngomalacia and developmental delay. Array CGH analysis revealed a 649 kb duplication on chromosome 1p34.1. Only five patients with overlapping duplications have been reported thus far. Ten known genes are located in the duplicated region, including the POMGNT1 gene encoding for O-mannose beta-1,2-N-acetylglucosaminyltransferase. This gene, mutated in muscle-eye-brain disease, might be causative for the observed phenotype in our patient.