Diagnosis of Cutaneous Mucormycosis Due to Rhizopus microsporus by an Innovative PCR-Restriction Fragment-Length Polymorphism Method

Larché, Jérôme; Machouart, M.; Burton, Kermit A.; Collomb, J.; Biava, M. F.; Gérard, Alain; Fortier, B

doi:10.1086/497078

Cited by 32 publications

(18 citation statements)

References 14 publications

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“…Methods such as in situ hybridization (8), conventional PCR (1,3,12,14,15,17) and nucleic acid sequencing (9,19) have been reported, but all suffer from a relatively long turnaround time compared to the time required for the clinical progression of a zygomycete infection. The application of real-time PCR methodologies is especially attractive as a choice for clinical diagnostics due to increases in detection sensitivity, reduction of outside contamination, and decreased test turnaround time.…”

Section: Discussionmentioning

confidence: 99%

Real-Time PCR Method for Detection of Zygomycetes

et al. 2008

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Zygomycete infections can be devastating in immunocompromised hosts. Difficulties in the histopathologic differentiation of this class from other filamentous fungi (e.g., Aspergillus spp., Fusarium spp.) may lead to delays in diagnosis and initiation of appropriate treatment, thereby significantly affecting patient outcome. A real-time PCR assay was developed to detect species of the zygomycete genera Absidia, Apophysomyces, Cunninghamella, Mucor, Rhizopus, and Saksenaea in culture and tissue samples. Primers and fluorescence resonance energy transfer hybridization probes were designed to detect a 167-bp conserved region of the multicopy zygomycete cytochrome b gene. A plasmid containing target sequence from Mucor racemosus was constructed as a positive control. The analytical sensitivity of the assay is 10 targets/l, and a specificity panel consisting of other filamentous fungi, yeasts (Candida spp.), and bacteria demonstrated no cross-reactivity in the assay. The clinical sensitivity and specificity of the assay from culture isolates were 100% (39/39) and 92% (59/64), respectively. Sensitivity and specificity determined using a limited number of fresh tissue specimens were both 100% (2/2). The sensitivity seen with formalin-fixed, paraffin-embedded tissues was 56% (35/62), and the specificity was 100% (19/19). The speed, sensitivity, and specificity of the PCR assay indicate that it is useful for the rapid and accurate detection of zygomycetes.Zygomycetes are common environmental fungi capable of producing serious disease in immunocompromised hosts. The vast majority of infections occur in individuals who are neutropenic, those receiving cytotoxic therapies, or those who have underlying metabolic acidosis. Although previously considered a relatively rare cause of disease, the incidence of opportunistic infections due to zygomycetes has increased over the last decade. Studies from multiple centers have indicated infection rates from 2.5% in bone marrow transplant recipients to 5.7% in solid-organ transplant recipients (10). Depending on the patient population, underlying disease, clinical presentation, and an early, accurate diagnosis, overall mortality rates due to zygomycete infections have ranged from 20% in localized infections to 100% in cases of disseminated disease (5, 13).Members of the order Mucorales include species of the genera Rhizopus, Absidia, Mucor, Rhizomucor, Apophysomyces, Cunninghamella, and Saksenaea, and all have been implicated in human disease. Approximately 90% of all infections are caused by members of the genus Rhizopus, most commonly, R. arrhizus, followed by R. microsporus var. rhizopodiformis.Currently, a diagnosis of zygomycosis is based upon identification of broad, ribbon-like, pauciseptate hyphae by histopathology or the use of macroscopic and microscopic morphology analysis following fungal culture. Histopathology determinations suffer from subjectivity that is dependent upon the experience of the reader. In addition, tissue processing, fixation, and staining may require sever...

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Section: Discussionmentioning

confidence: 99%

Real-Time PCR Method for Detection of Zygomycetes

et al. 2008

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“…Reference laboratories should receive at least clinically relevant or difficult-to-identify strains (368). These procedures would help clinicians to narrow therapeutic approaches (180), which is especially important as more antifungal drugs become available.…”

Section: Diagnosismentioning

confidence: 99%

Mucormycosis Caused by Unusual Mucormycetes, Non-Rhizopus, -Mucor, and -Lichtheimia Species

2011

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SUMMARY Rhizopus , Mucor , and Lichtheimia (formerly Absidia ) species are the most common members of the order Mucorales that cause mucormycosis, accounting for 70 to 80% of all cases. In contrast, Cunninghamella , Apophysomyces , Saksenaea , Rhizomucor , Cokeromyces , Actinomucor , and Syncephalastrum species individually are responsible for fewer than 1 to 5% of reported cases of mucormycosis. In this review, we provide an overview of the epidemiology, clinical manifestations, diagnosis of, treatment of, and prognosis for unusual Mucormycetes infections (non- Rhizopus , - Mucor , and - Lichtheimia species). The infections caused by these less frequent members of the order Mucorales frequently differ in their epidemiology, geographic distribution, and disease manifestations. Cunninghamella bertholletiae and Rhizomucor pusillus affect primarily immunocompromised hosts, mostly resulting from spore inhalation, causing pulmonary and disseminated infections with high mortality rates. R. pusillus infections are nosocomial or health care related in a large proportion of cases. While Apophysomyces elegans and Saksenaea vasiformis are occasionally responsible for infections in immunocompromised individuals, most cases are encountered in immunocompetent individuals as a result of trauma, leading to soft tissue infections with relatively low mortality rates. Increased knowledge of the epidemiology and clinical presentations of these unusual Mucormycetes infections may improve early diagnosis and treatment.

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“…Recovery of Zygomycetes from tissue can be problematic, and fungal detection is often hindered by the absence of fungal growth in culture; therefore, the diagnosis is often delayed or made postmortem. Furthermore, Larché et al 61 and Nosari et al 62 proposed use of a molecular test to enable rapid identification of Mucorales at the genus and species levels.…”

Section: Discussionmentioning

confidence: 99%