Invasive Gastrointestinal Mucormycosis: A Master Masquerader

We report 3 previously healthy children of postneonatal age who developed fatal form of gastrointestinal mucormycosis after systemic inflammatory response syndrome, shock and metabolic acidosis. Abdominal distension and peritonitis were secondary complications. The study highlights the importance of clinical suspicion of gastrointestinal mucormycosis when the triad of shock requiring vasoactive drugs, metabolic acidosis and abdominal distension is present.

Gastrointestinal Mucormycosis following a Streptococcus pyogenes Toxic Shock Syndrome in a Previously Healthy Patient: A Case Report

Mucormycosis is an uncommon opportunistic infection and the gastrointestinal form is the rarest. Rhizopus sp. is the most frequent pathogen and infection occurs almost exclusively in immunocompromised patients. We describe the first case of intestinal mucormycosis occurring after a Streptococcus pyogenes toxic shock syndrome in a previously healthy patient caused by Rhizopus microsporus var. azygosporus.

Epidemiology and clinical manifestations of mucormycosis

Mucormycosis is an emerging angioinvasive infection caused by the ubiquitous filamentous fungi of the Mucorales order of the class of Zygomycetes. Mucormycosis has emerged as the third most common invasive mycosis in order of importance after candidiasis and aspergillosis in patients with hematological and allogeneic stem cell transplantation. Mucormycosis also remains a threat in patients with diabetes mellitus in the Western world. Furthermore, this disease is increasingly recognized in recently developed countries, such as India, mainly in patients with uncontrolled diabetes or trauma. Epidemiological data on this type of mycosis are scant. Therefore, our ability to determine the burden of disease is limited. Based on anatomic localization, mucormycosis can be classified as one of 6 forms: (1) rhinocerebral, (2) pulmonary, (3) cutaneous, (4) gastrointestinal, (5) disseminated, and (6) uncommon presentations. The underlying conditions can influence clinical presentation and outcome. This review describes the emerging epidemiology and the clinical manifestations of mucormycosis.

Biofilm formation by zygomycetes: quantification, structure and matrix composition

Most studies on fungal biofilms have focused on Candida in yeasts and Aspergillus in mycelial fungi. To the authors’ knowledge, biofilm formation by zygomycetes has not been reported previously. In this study, the biofilm-forming capacity of Rhizopus oryzae, Lichtheimia corymbifera, Rhizomucor pusillus and Apophysomyces elegans was evaluated. At appropriate seeding spore densities, Rhp . oryzae (105 c.f.u. ml−1), L. corymbifera (104 c.f.u. ml−1) and Rhm. pusillus (104 c.f.u. ml−1) produced highly intertwined, adherent structures on flat-bottomed polystyrene microtitre plates after 24 h at 37 °C. The adhered fungal hyphae were encased in an extracellular matrix, as confirmed by phase-contrast and confocal microscopy. The thickness of Rhp. oryzae, L. corymbifera and Rhm. pusillus biofilms was 109.67±10.02, 242±23.07 and 197±9.0 µm (mean±sd), respectively. Biochemical characterization of the biofilm matrix indicated the presence of glucosamine, constituting 74.54–82.22 % of its dry weight, N-acetylglucosamine, glucose and proteins. Adherence and biofilm formation were not observed in A. elegans. Although A. elegans spores germinated at all three seeding densities tested (1×107, 1×106 and 1×105 c.f.u. ml−1), no significant difference was observed (P>0.05) between the A 490 of wells inoculated with A. elegans and the cut-off A 490 for biofilm detection. This study highlights the potential for biofilm formation by at least three medically important species of zygomycetes.

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.

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.