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Isolation of Rhizopus microsporus and Lichtheimia corymbifera from tracheal aspirates of two immunocompetent critically ill patients with COVID-19.

ABSTRACT: We describe two fatal cases of COVID-19 in which Rhizopus microsporus and Lichtheimia corymbifera were cultured from endotracheal aspirate samples. Both patients had no underlying comorbidities other than obesity. Despite antifungal therapy, both cases developed septic shock and progressive refractory hypoxemia without evidence of other underlying infections. It is unclear whether isolation of these fungal organisms represents invasive disease or corresponds to an epiphenomenon of critical illness. Yet, patients suffering from COVID-19 may be at risk of superinfection from a broader range of fungal organisms than previously thought.

SUBMITTER: Fernandez-Garcia O

PROVIDER: S-EPMC8268675 | biostudies-literature | 2021 Sep

REPOSITORIES: biostudies-literature

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Isolation of Rhizopus microsporus and Lichtheimia corymbifera from tracheal aspirates of two immunocompetent critically ill patients with COVID-19.

Fernández-García Oscar O Guerrero-Torres Lorena L Roman-Montes Carla M CM Rangel-Cordero Andrea A Martínez-Gamboa Areli A Ponce-de-Leon Alfredo A Gonzalez-Lara María F MF

Medical mycology case reports 20210709

We describe two fatal cases of COVID-19 in which Rhizopus microsporus and Lichtheimia corymbifera were cultured from endotracheal aspirate samples. Both patients had no underlying comorbidities other than obesity. Despite antifungal therapy, both cases developed septic shock and progressive refractory hypoxemia without evidence of other underlying infections. It is unclear whether isolation of these fungal organisms represents invasive disease or corresponds to an epiphenomenon of ...[more]

PMID: 34307008

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Project description:Pathogenic mucormycetes induce diseases with considerable morbidity and mortality in immunocompromised patients. Virulence data comparing different Mucorales species and various underlying risk factors are limited. We therefore compared the pathogenesis of inhalative infection by Rhizopus (R.) arrhizus and Lichtheimia (L.) corymbifera in murine models for predominant risk factors for onset of infection. Mice with diabetes or treated with cyclophosphamide or cortisone acetate were challenged via the intranasal route with an isolate of R. arrhizus or L. corymbifera, respectively. Clinical, immunological and inflammation parameters as well as efficacy of posaconazole prophylaxis were monitored over 14 days. Whereas immunocompetent mice showed no clinical symptoms after mucormycete infection, mice treated with either cyclophosphamide (CP) or cortisone acetate (CA) were highly susceptible. Animals infected with the isolate of R. arrhizus showed prolonged survival and lower mortality, compared to those exposed to the L. corymbifera isolate. This lower virulence of R. arrhizus was risk factor-dependent, since diabetic mice died only after infection with Rhizopus, whereas all Lichtheimia-infected diabetic animals survived. Under posaconazole prophylaxis, both mucormycetes were able to establish breakthrough infections in CA- and CP-treated mice, but the course of infection was significantly delayed. Detailed analysis revealed that susceptibility of CA- and CP-treated mice could not be mimicked by exclusive lack or downmodulation of neutrophils, platelets or complement, but can be supposed to be the consequence of a broad immunosuppressive effect induced by the drugs. Both Lichtheimia corymbifera and Rhizopus arrhizus induce invasive mycoses in immunocompromised hosts after inhalative infection. Key parameters such as virulence and immunopathogenesis vary strongly according to fungal species and underlying risk group. Selected neutropenia is no sufficient risk factor for onset of inhalative mucormycosis.

Project description:Sinopulmonary and rhinocerebral zygomycosis has been increasingly found in patients with hematological malignancies and bone marrow transplantation, but intestinal zygomycosis remains very rare in the literature. We investigated an outbreak of intestinal infection due to Rhizopus microsporus in 12 patients on treatment for hematological malignancies over a period of 6 months in a teaching hospital. The intake of allopurinol during hospitalization (P < 0.001) and that of commercially packaged ready-to-eat food items in the preceding 2 weeks (P < 0.001) were found to be independently significant risk factors for the development of intestinal zygomycosis. A total of 709 specimens, including 378 environmental and air samples, 181 food samples, and 150 drug samples, were taken for fungal culture. Among them, 16 samples of allopurinol tablets, 3 prepackaged ready-to-eat food items, and 1 pair of wooden chopsticks were positive for Rhizopus microsporus, which was confirmed by ITS1-5.8S-ITS2 rRNA gene cluster (internal transcribed spacer [ITS]) sequencing. The mean viable fungal counts of allopurinol obtained from wards and pharmacy were 4.22 x 10(3) CFU/g of tablet (range, 3.07 x 10(3) to 5.48 x 10(3)) and 3.24 x 10(3) CFU/g of tablet (range, 2.68 x 10(3) to 3.72 x 10(3)), respectively, which were much higher than the mean count of 2 x 10(2) CFU/g of food. Phylogenetic analysis by ITS sequencing showed multiple clones from isolates of contaminated allopurinol tablets and ready-to-eat food, of which some were identical to patients' isolates, and with one isolate in the cornstarch used as an excipient for manufacture of this drug. We attempted to type the isolates by random amplification of polymorphic DNA analysis, with limited evidence of clonal distribution. The primary source of the contaminating fungus was likely to be the cornstarch used in the manufacturing of allopurinol tablets or ready-to-eat food. Rhizopus microsporus is thermotolerant and can multiply even at 50 degrees C. The long holding time of the intermediates during the manufacturing process of allopurinol amplified the fungal load. Microbiological monitoring of drugs manufactured for highly immunosuppressed patients should be considered.

Dataset Information

Isolation of Rhizopus microsporus and Lichtheimia corymbifera from tracheal aspirates of two immunocompetent critically ill patients with COVID-19.

Publications

Isolation of <i>Rhizopus microsporus</i> and <i>Lichtheimia</i> corymbifera from tracheal aspirates of two immunocompetent critically ill patients with COVID-19.

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