A case of peritonitis caused by Rhizopus microsporus

A Repertoire of Clinical Non-Dermatophytes Moulds

Humans are constantly exposed to micromycetes, especially filamentous fungi that are ubiquitous in the environment. In the presence of risk factors, mostly related to an alteration of immunity, the non-dermatophyte fungi can then become opportunistic pathogens, causing superficial, deep or disseminated infections. With new molecular tools applied to medical mycology and revisions in taxonomy, the number of fungi described in humans is rising. Some rare species are emerging, and others more frequent are increasing. The aim of this review is to (i) inventory the filamentous fungi found in humans and (ii) provide details on the anatomical sites where they have been identified and the semiology of infections. Among the 239,890 fungi taxa and corresponding synonyms, if any, retrieved from the Mycobank and NCBI Taxonomy databases, we were able to identify 565 moulds in humans. These filamentous fungi were identified in one or more anatomical sites. From a clinical point of view, this review allows us to realize that some uncommon fungi isolated in non-sterile sites may be involved in invasive infections. It may present a first step in the understanding of the pathogenicity of filamentous fungi and the interpretation of the results obtained with the new molecular diagnostic tools.

Zygomycetes peritonitis in ambulatory peritoneal dialysis: Case report and review of literature

We present a case of CAPD peritonitis caused by zygomycetes infection. A 46-year-old male patient presented with refractory peritonitis requiring catheter removal. He had persistence of fever and an ultrasonography abdomen done revealed loculated collections. An initial pigtail drainage followed by open laparotomy was performed. Intra-operative peritoneal and omental biopsy revealed large areas of necrosis with broad aseptate fungal hyphae consistent with zygomycosis. He was managed with 3 gm of intravenous amphotericin and is doing well at 6 months of follow-up.

Intra-abdominal Rhizopus microsporus infection successfully treated by combined aggressive surgical, antifungal, and iron chelating therapy

Zygomycetes are widely distributed in the environment as inhabitants of soil and decaying matter. On rare occasions, these organisms can cause invasive infections in immunocompromised hosts. As zygomycetes are resistant to most conventional antifungal agents, its infection is often fatal. We report 2 cases of unusual intra-abdominal Rhizopus microsporus infection in children with acute leukemia as a result of an unprecedented outbreak due to oral intake of contaminated allopurinol tablets and ready-to-eat food items. Among the 2 patients, one of them survived after aggressive combined surgical, antifungal (AmBisome, Caspofungin, and Posaconazole) and iron chelation therapy.

Fatal peritonitis caused by Rhizopus microsporus

A 52-year-old woman with a history of Crohn's disease was admitted due to peritonitis which followed an intestinal perforation. After transitory treatment with voriconazole, resolution of the infection was complicated by recurring peritonitis resulting from necrosis and perforation of the left colon which ultimately lead to the death of the patient. Microscopic examination of the peritoneal fluid revealed the presence of broad, irregular hyphae and culture of the fluid yielded Rhizopus microsporus. The identification of the fungus was confirmed by its characteristic microscopic morphology and sequencing of the ITS region of the rDNA. The histopathologic examination of the colon tissue demonstrated the presence of broad, non-septate hyphae and the same fungus was again isolated in culture.

An update on the molecular diagnosis of invasive fungal disease

Despite improvements in medical technology, the definitive diagnosis of invasive fungal disease (IFD) is limited. The prevalence of disease is relatively low but many cases are undiagnosed. With the diagnosis of proven IFD dependent on histopathology or culture from a sterile site, clinicians have become more reliant on noninvasive nonculture diagnostic techniques. PCR technology has the capacity to overcome classical limitations but has its own drawbacks, resulting from an incomplete knowledge of the various disease processes and subsequent shortage of optimal specimens, leading to a lack of methodological standardization. This review will consider the general principles and limitations of fungal PCR before discussing genus-specific PCR applications. It is by no means a systematic review of the literature but is intended, where possible, to provide the reader with access to assays with proficient clinical performance.

Detection of a molecular biomarker for zygomycetes by quantitative PCR assays of plasma, bronchoalveolar lavage, and lung tissue in a rabbit model of experimental pulmonary zygomycosis

We developed two real-time quantitative PCR (qPCR) assays, targeting the 28S rRNA gene, for the diagnosis of zygomycosis caused by the most common, clinically significant Zygomycetes. The amplicons of the first qPCR assay (qPCR-1) from Rhizopus, Mucor, and Rhizomucor species were distinguished through melt curve analysis. The second qPCR assay (qPCR-2) detected Cunninghamella species using a different primer/probe set. For both assays, the analytic sensitivity for the detection of hyphal elements from germinating sporangiospores in bronchoalveolar lavage (BAL) fluid and lung tissue homogenates from rabbits was 1 to 10 sporangiospores/ml. Four unique and clinically applicable models of invasive pulmonary zygomycosis served as surrogates of human infections, facilitating the validation of these assays for potential diagnostic utility. For qPCR-1, 5 of 98 infarcted lung specimens were positive by qPCR and negative by quantitative culture (qCx). None were qCx positive only. Among 23 BAL fluid samples, all were positive by qPCR, while 22 were positive by qCx. qPCR-1 detected Rhizopus and Mucor DNA in 20 (39%) of 51 serial plasma samples as early as day 1 postinoculation. Similar properties were observed for qPCR-2, which showed greater sensitivity than qCx for BAL fluid (100% versus 67%; P = 0.04; n = 15). The assay detected Cunninghamella DNA in 18 (58%) of 31 serial plasma samples as early as day 1 postinoculation. These qPCR assays are sensitive and specific for the detection of Rhizopus, Mucor, Rhizomucor, and Cunninghamella species and can be used for the study and detection of infections caused by these life-threatening pathogens.

Mucormycosis peritonitis: more than 2 years of disease-free follow-up after posaconazole salvage therapy after failure of liposomal amphotericin B

A 57-year-old woman with end-stage kidney disease secondary to autosomal dominant polycystic kidney disease developed peritoneal dialysis-related Mucor peritonitis after her pet cockatoo bit through her transfer set. The infection persisted despite more than 8 weeks of treatment with liposomal amphotericin B. On a compassionate basis, she then received oral posaconazole, 800 mg/d, in divided doses for 6 months. She experienced complete remission and has remained disease free since then, for more than 2 years. We review the medical literature about mucormycosis peritonitis which, albeit rare, carries very high mortality. The treatment of choice is liposomal amphotericin B, which failed in our patient. Our case report suggests that posaconazole is an attractive treatment option in patients with peritoneal dialysis-related Mucor peritonitis.