17 years at Ege, then a cutoff
Ege University Hospital collected Candida parapsilosis bloodstream isolates from 2007 to 2024. In 2007–2010 every isolate was fluconazole-susceptible. Over the next decade, fluconazole-resistant isolates carrying the Erg11Y132F substitution progressively displaced the susceptible population and dominated in 2019–2022. That is a long hospital series, not a snapshot. How many years? The resistant lineage's dominant window is 2019–2022, after the susceptible period.[1]
The same paper then scored biofilm on 120 clinical Candida parapsilosis isolates: 95 from that historic Turkish outbreak and 25 from an early-stage outbreak in Brazil. A crystal-violet reading of OD490 below 0.05 classified an isolate as low-biofilm-producing (LBP); OD490 at or above 0.05 classified it as a biofilm producer, and below that line the wells stayed transparent and held no stain. Every Turkish FLCR Erg11Y132F isolate fell below that line. Most of the Brazilian isolates, collected earlier in their outbreak, still made robust biofilm. The Turkish LBP isolates were all fluconazole-resistant; the Brazilian set mixed resistant and susceptible.[1]
The mechanism's denominator
The metabolic-rewiring claim sits on RNA-seq of 4 isolates: 29T and 49B (LBP, YCP lineage) against 1T and 35B (biofilm producers, fluconazole-susceptible). Profiles were taken at 90 min, 8 h and 24 h, the adhesion, initiation and maturation points, in biofilm and planktonic culture, with 3 biological replicates per sample. How many samples? 4 in the RNA-seq. That design describes those 4 genomes. It does not estimate the transcription of a 95-isolate hospital population.[1]
Whole-genome sequencing at coverage above 100x covered 16 Turkish and Brazilian strains chosen for biofilm class, susceptibility and ERG11 mutations. A further 16 Italian isolates — 15 FLCR LBP and 1 fluconazole-susceptible biofilm producer — formed a tight LBP cluster distant from the Turkish and Brazilian LBP clades. American and Canadian collections entered as published genomes; biofilm scores were missing there except for a Canadian subset tested after it clustered with the Turkish LBP strains. In mice, 3–4 animals per isolate per time point, fungal burden at day 4 and day 7 was not statistically distinguishable in kidney and liver; the spleen, rich in macrophages, was the organ where LBP isolates sat higher.[1]
What the classification can carry
The headline that outbreaks are carried by the weakest biofilms is therefore a classification coinciding with a lineage that already dominated a hospital. Host selection, immune evasion and an adaptive tradeoff are the authors' reading of the thinner experiments. A live alternative is that LBP may travel with the Erg11Y132F clonal background rather than mark a host-selected attenuation, and that the Brazilian early-stage mix of biofilm classes among resistant isolates is what a young outbreak still looks like.[1]
The authors themselves say the same biofilm role in Candida auris and Candida tropicalis needs a separate study. The pulse worth waiting for is a second long bloodstream series, scored on the same OD490 0.05 line. If FLCR Erg11Y132F isolates there also sit uniformly below the cutoff after a comparable number of years, the Ege classification generalizes. If a mixed resistant population persists at that duration, Ege remains a local pattern. Until that series exists, the hospital replacement is the result; the host-selection story is a hypothesis. Until it repeats, we wait.[1]