Detection of Specific IgE against Molds Involved in Allergic Bronchopulmonary Mycoses in Patients with Cystic Fibrosis.

CONTEXT: Allergic bronchopulmonary mycoses (ABPM) can be due to molds other than Aspergillus fumigatus in patients with cystic fibrosis (pwCF). We aimed to develop immunoassays for the detection of specific IgE (sIgE) directed against five fungal species involved in ABPM: Aspergillus terreus, Scedosporium apiospermum, Lomentospora prolificans, Rasamsonia argillacea, and Exophiala dermatitidis. MATERIALS AND METHODS: Serum samples (n = 356) from 238 pwCF, collected in eight CF care centers in France, Germany, and Italy, were analyzed by dissociated enhanced lanthanide fluorescent immunoassay (DELFIA®) to assess levels of sIgE directed against antigenic extracts of each fungus. Clinical, biological, and radiological data were collected for each episode. One hundred serum samples from healthy blood donors were used as controls. Sera were classified into four groups depending on the level of sIgE according to the quartile repartition calculated for the pwCF population. A score of 4 for values above the 3rd quartile corresponds to an elevated level of sIgE. RESULTS: PwCF showed higher levels of sIgE than controls. Based on criteria from the ABPA-ISHAM working group, with an additional criterion of "a sIgE score of 4 for at least one non-A. fumigatus mold", we were able to diagnose six cases of ABPM. CONCLUSIONS: Using 417 IU/mL as the threshold for total IgE and the same additional criterion, we identified seven additional pwCF with "putative ABPM". Detection of sIgE by DELFIA® showed good analytical performance and supports the role played by non-A. fumigatus molds in ABPM. However, commercially available kits usable in routine practice are needed to improve the diagnosis of ABPM.

Atovaquone exposure and Pneumocystis jirovecii cytochrome b mutations: French data and review of the literature.

Pneumocystis jirovecii is a transmissible fungus responsible for severe pneumonia (Pneumocystis pneumonia [PCP]) in immunocompromised patients. Missense mutations due to atovaquone selective pressure have been identified on cytochrome b (CYB) gene of P. jirovecii. It was recently shown that atovaquone prophylaxis can lead to the selection of specific P. jirovecii CYB mutants potentially resistant to atovaquone among organ transplant recipients. In this context, our objectives were to provide data on P. jirovecii CYB mutants and the putative selective pressure exerted by atovaquone on P. jirovecii organisms in France. A total of 123 patients (124 P. jirovecii specimens) from four metropolitan hospitals and two overseas hospitals were retrospectively enrolled. Fourteen patients had prior exposure to atovaquone, whereas 109 patients did not at the time of P. jirovecii detection. A 638 base-pair fragment of the CYB gene of P. jirovecii was amplified and sequenced. A total of 10 single nucleotide polymorphisms (SNPs) were identified. Both missense mutations C431T (Ala144Val) and C823T (Leu275Phe), located at the Qo active site of the enzyme, were significantly associated with prior atovaquone exposure, these mutations being conversely incidental in the absence of prior atovaquone exposure (P < 0.001). Considering that the aforementioned hospitals may be representative of the national territory, these findings suggest that the overall presence of P. jirovecii CYB mutants remains low in France.

The mutations C431T (Ala144Val) and C823T (Leu275Phe) at the cytochrome b (CYB) active site of Pneumocystis jirovecii are associated with patient prior exposure to atovaquone. Conversely, these mutations are incidental in the absence of exposure. Overall, the presence of P. jirovecii CYB mutants remains low in France.

Apparent Absence of Selective Pressure on Pneumocystis jirovecii Organisms in Patients with Prior Methotrexate Exposure.

Pneumocystis jirovecii infections occur in patients treated with methotrexate (MTX) because of immunosuppressive effects of this highly potent dihydrofolate reductase (DHFR) inhibitor. Conversely, MTX may act as an anti-P. jirovecii drug and consequently may exert a selective pressure on this fungus. In this context, we compared the sequences of the dhfr gene of P. jirovecii isolates obtained from two groups of patients with P. jirovecii infections. The first group, with systemic diseases or malignancies, had prior exposure to MTX (21 patients), whereas the second group (22 patients), the control group, did not. Three single nucleotide polymorphisms (SNPs) were observed at positions 278, 312, and 381. The first one was located in the intronic region and the two others were synonymous. Based on these SNPs, three P. jirovecii dhfr alleles, named A, B, and C, were specified. Allele A was the most frequent, as it was observed in 18 patients (85.7%) and in 16 patients (72.7%) of the first and second groups, respectively. No significant difference in P. jirovecii dhfr gene diversity in the two patient groups was observed. In conclusion, these original results suggest that MTX does not exert an overt selective pressure on P. jirovecii organisms.

Highly Conserved gsc1 Gene of Pneumocystis jirovecii in Patients with or without Prior Exposure to Echinocandins.

Echinocandins are noncompetitive inhibitors of the GSC1 subunit of the enzymatic complex involved in synthesis of 1,3-beta-d-glucan, a cell wall component of most fungi, including Pneumocystis spp. Echinocandins are widely used for treating systemic candidiasis and rarely used for treating Pneumocystis pneumonia. Consequently, data on P. jirovecii gsc1 gene diversity are still scarce compared to that for the homologous fks1 gene of Candida spp. In this study, we analyzed P. jirovecii gsc1 gene diversity and the putative selection pressure of echinocandins on P. jirovecii. gsc1 gene sequences of P. jirovecii specimens from two patient groups were compared. One group of 27 patients had prior exposure to echinocandins, whereas the second group of 24 patients did not, at the time of P. jirovecii infection diagnoses. Two portions of the P. jirovecii gsc1 gene, HS1 and HS2, homologous to hot spots described in Candida spp., were sequenced. Three single-nucleotide polymorphisms (SNPs) at positions 2204, 2243, and 2303 close to the HS1 region and another SNP at position 4540 more distant from the HS2 region were identified. These SNPs represent synonymous mutations. Three gsc1 HS1 alleles, A, B, and C, and two gsc1 HS2 alleles, a and b, and four haplotypes, Ca, Cb, Aa, and Ba, were defined, without significant difference in haplotype distribution in both patient groups (P = 0.57). Considering the identical diversity of P. jirovecii gsc1 gene and the detection of synonymous mutations in both patient groups, no selection pressure of echinocandins among P. jirovecii microorganisms can be pointed out so far.

Selection of Pneumocystis jirovecii Inosine 5'-Monophosphate Dehydrogenase Mutants in Solid Organ Transplant Recipients: Implication of Mycophenolic Acid.

Mycophenolic acid (MPA) targets the inosine 5'-monophosphate dehydrogenase (IMPDH) of human lymphocytes. It is widely used as an immunosuppressant to prevent rejection in solid organ transplant (SOT) recipients who, incidentally, are at risk for Pneumocystis pneumonia (PCP). We hypothesized that MPA exerts selective pressure on P. jirovecii microorganisms considering its in vitro antifungal activity on other fungi. Thus, we analysed impdh gene in P. jirovecii isolates from SOT recipients. P. jirovecii specimens from 26 patients diagnosed with PCP from 2010 to 2020 were retrospectively examined: 10 SOT recipients treated with MPA and 16 non-SOT patients without prior exposure to MPA. The P. jirovecii impdh gene was amplified and sequenced. Nucleotide sequences were aligned with the reference sequences retrieved from available P. jirovecii whole genomes. The deduced IMPDH protein sequences were aligned with available IMPDH proteins from Pneumocystis spp. and other fungal species known to be in vitro sensitive or resistant to MPA. A total of nine SNPs was identified. One SNP (G1020A) that results in an Ala261Thr substitution was identified in all SOT recipients and in none of the non-SOT patients. Considering that IMPDHs of other fungi, resistant to MPA, harbour Thr (or Ser) at the analogous position, the Ala261Thr mutation observed in MPA-treated patients was considered to represent the signature of P. jirovecii exposure to MPA. These results suggest that MPA may be involved in the selection of specific P. jirovecii strains that circulate in the SOT recipient population.

Is hypophosphataemia an independent predictor of mortality in critically ill patients with bloodstream infection? A multicenter retrospective cohort study.

BACKGROUND: Hypophosphataemia affects up to one-third of patients in the intensive care unit (ICU) and is particularly common during sepsis. Experimental data suggest that hypophosphataemia leads to an acquired dysfunction of leukocytes, thus promoting infections and increasing the risk of death during sepsis. OBJECTIVES: The aim of our study was to investigate the association between hypophosphataemia and mortality in critically ill patients with a bloodstream infection (BSI). METHODS: We performed a retrospective study in three ICUs during an 18-month period. All adults with a BSI diagnosed in the ICU were eligible. Patients with and without hypophosphataemia, defined as phosphataemia below 0.8 mmol/L, were compared. A multivariate survival analysis using a Cox proportional hazard regression model was conducted to study the association between hypophosphataemia and 90-d mortality. RESULTS/FINDINGS: Among the 3783 patients admitted to the three participating ICUs within the 18-month study period, 203 met the inclusion criteria and 193 were analysed. Fifty-four patients had hypophosphataemia. After adjusting for confounders, hypophosphataemia was significantly associated with a twofold increased risk of 90-d mortality (hazard ratio = 2.10 [1.177-3.80], p = 0.013). This association is particularly strong in patients without shock. CONCLUSIONS: Hypophosphataemia was independently associated with a twofold increase in 90-d mortality in ICU patients with a BSI. These results suggest that investigators and physicians should include phosphataemia as a predictor of the severity of BSIs. Further research is warranted to better understand this association and to determine the potential benefits of systematic monitoring of phosphataemia and phosphorus supplementation. CLINICAL TRIAL REGISTRATION: NCT03529058.

Mucorales DNA detection in serum specimens for early diagnosis of mucormycosis.

We report a case of pulmonary mucormycosis in a patient with T-cell acute lymphoblastic leukemia. The diagnosis of mucormycosis was initially based on mycological examination of a pulmonary specimen. However, we describe how it could have been made 2 months earlier using polymerase chain reaction assays targeting Mucorales species on serum specimens.

A very potent factor V inhibitor interferes with the levels of all coagulation factors and causes a fatal hemorrhagic syndrome.

We report a very high factor V inhibitor affecting the measurement of all coagulation factors besides fibrinogen, all these factors being dramatically decreased. This inhibitor could be linked to antibiotic use. The patient died of massive hemorrhage before a plasma exchange could be initiated.