ZYGOMYCOSIS: Current approaches to management of patients with haematological malignancies

[Mucormycosis: Current and future management perspective]

Infections caused by mucorales, with an increasing incidence after candidiasis and aspergillosis, are characterized by the fast angioinvasion of blood vessels and invasion of neighboring organs or structures. Mucorales most commonly cause rhinocerebral, pulmonary, cutaneous, digestive or disseminated infections, and their spread is favored by certain underlying diseases (diabetes, kidney failure) and risk factors (neutropenia, immunosuppression, iron overload). These infections have a high mortality rate, over 40% in many series, and the key to their cure depends on both an early diagnosis and an antifungal treatment, associated in most cases with extensive surgical debridement and other adjunctive therapies. Currently, there are international guidelines, not only local ones, for the management of mucormycosis, in which it is considered by consensus and with a strong recommendation that first-line treatment with high-dose liposomal amphotericin B is the best choice. The combined antifungal treatment of polyene agents with triazoles or candins remains in open debate.

Severe meningoencephalitis secondary to calvarial invasion of Lagenidium giganteum forma caninum in a dog

Background:

The oomycete Lagenidiumgiganteum forma caninum is an uncommon cause of severe dermal and subcutaneous infections in dogs with possible vascular invasion and other fatal sequelae. Infection within the central nervous system of affected dogs has not been previously reported.

Case Description:

A 6-year-old spayed female mixed-breed dog was evaluated at a referral institution with a 2-month history of suspected fungal infection in the region of the right mandibular lymph node that was refractory to surgical resection and empiric medical therapy. Physical examination identified a 6-cm fluctuant subcutaneous mass caudoventral to the ramus of the right mandible and a second firm mass in the region of the right caudal maxilla. Lesional punch biopsies were submitted for fungal culture and polymerase chain reaction (PCR), which subsequently identified L. giganteum forma caninum infection. Initial treatment consisted of anti-inflammatory doses of prednisone and hyperbaric oxygen therapy. Four weeks following initial evaluation, the patient was presented with progressive neurological signs consistent with a forebrain lesion. Magnetic resonance imaging revealed soft-tissue, contrast-enhancing lesions ventral to the calvarium adjacent to the site of original surgical resection and throughout the brain. Humane euthanasia was elected, and postmortem examination was consistent with the extension of local disease from the right masseter muscle into the right ventral calvarium. Postmortem DNA sequencing confirmed the identity of the organism as L. giganteum forma caninum.

Conclusion:

This is the first reported case of intracranial lagenidiosis in the dog. PCR distinguished this species from other Lagenidium species and from oomycetes of other genera, such as Pythiuminsidiosum and Paralagenidium karlingii. Regional extension of cutaneous lagenidiosis should therefore be considered in cases with concurrent or spontaneous neurologic disease.

Successful posaconazole salvage therapy for rhinocerebral mucormycosis in a child with leukemia. Review of the literature

BACKGROUND

Mucormycosis is a fungal infection caused by species of the Mucorales order. These microorganisms are angioinvasive, with rapid disease progression and potentially lethal in its rhinocerebral form.

CASE REPORT

We present the case of a 12-year-old female with trisomy 21, acute lymphoblastic leukemia and diabetes, with fever and neutropenia who developed rhinocerebral mucormicosis. After treatment with amphotericin B lipid complex and extensive surgery, disease progressed and posaconazole was added as salvage treatment with full remission of the infection. Four years after diagnosis the patient continues without relapse of mucormycosis or leukemia.

CONCLUSIONS

This case highlights the use of posaconazole as either monotherapy or combined therapy. Although it is still debated, it can be considered an option for salvage treatment in children with non-responding mucormycosis, despite lack of standard dosage in pediatric patients.

Mucorales-Specific T Cells in Patients with Hematologic Malignancies

Background

Invasive mucormycosis (IM) is an emerging life-threatening fungal infection. It is difficult to obtain a definite diagnosis and to initiate timely intervention. Mucorales-specific T cells occur during the course of IM and are involved in the clearance of the infection. We have evaluated the feasibility of detecting Mucorales-specific T cells in hematological patients at risk for IM, and have correlated the detection of such cells with the clinical conditions of the patients.

Methods and Findings

By using an enzyme linked immunospot assay, the presence of Mucorales-specific T cells in peripheral blood (PB) samples has been investigated at three time points during high-dose chemotherapy for hematologic malignancies. Mucorales-specific T cells producing interferon-γ, interleukin-10 and interleukin-4 were analysed in order to detect a correlation between the immune response and the clinical picture. Twenty-one (10.3%) of 204 patients, accounting for 32 (5.3%) of 598 PB samples, tested positive for Mucorales-specific T cells. Two groups could be identified. Group 1, including 15 patients without signs or symptoms of invasive fungal diseases (IFD), showed a predominance of Mucorales-specific T cells producing interferon-gamma. Group 2 included 6 patients with a clinical picture consistent with invasive fungal disease (IFD): 2 cases of proven IM and 4 cases of possible IFD. The proven patients had significantly higher number of Mucorales-specific T cells producing interleukin-10 and interleukin-4 and higher rates of positive samples by using derived diagnostic cut-offs when compared with the 15 patients without IFD.

Conclusions

Mucorales-specific T cells can be detected and monitored in patients with hematologic malignancies at risk for IM. Mucorales-specific T cells polarized to the production of T helper type 2 cytokines are associated with proven IM and may be evaluated as a surrogate diagnostic marker for IM.

Invasive coinfection with Aspergillus and Mucor in a patient with acute myeloid leukemia

The authors report the case of a 58-year-old female patient with a life-threatening invasive fungal disease caused by a coinfection of Aspergillus and Mucor species that occurred during induction and consolidation chemotherapy for an acute myeloid leukemia. The disease was successfully treated with an aggressive therapeutic approach, which consisted of liposomal amphotericin B in combination with surgical exploration without compromising the treatment of her underlying disease. The case demonstrates the difficulties associated with establishing a diagnosis as well as the need for close observation to identify these infections, which are often misdiagnosed and only suspected late during the course of the disease. Doubts about the reliability of the diagnostic tools lead to uncertainties with regard to the choice of first-line drugs as well the selection of the most appropriate therapeutic strategy in hematologic patients.

Development of a single tube multiplex real-time PCR to detect the most clinically relevant Mucormycetes species

Mucormycetes infections are very difficult to treat and a delay in diagnosis could be fatal for the outcome of the patient. A molecular diagnostic technique based on Real Time PCR was developed for the simultaneous detection of Rhizopus oryzae, Rhizopus microsporus and the genus Mucor spp. in both culture and clinical samples. The methodology used was Molecular beacon species-specific probes with an internal control. This multiplex real-time PCR (MRT-PCR) was tested in 22 cultured strains and 12 clinical samples from patients suffering from a proven mucormycosis. Results showed 100% specificity and a detection limit of 1 fg of DNA per microlitre of sample. The sensitivity was 100% for clinical cultured strains and for clinical samples containing species detected by the PCR assay. Other mucormycetes species were not detected in clinical samples. This technique can be useful for clinical diagnosis and further studies are warranted.

Mucormycosis treated with posaconazole: review of 96 case reports

Mucormycosis is an emerging invasive fungal infection, primarily affecting immunocompromised patients. The disease is difficult to diagnose and mortality reaches 40% even if treated adequately. Depending on site of infection and risk factors, surgical debridement in combination with systemically active antifungal drugs are the mainstay treatment strategies. Lipid-based amphotericin B is the treatment of choice for first-line therapy while posaconazole may be a promising alternative. We performed a PubMed search on reports of patients with mucormycosis treated with posaconazole. From 2003 to 2011, 96 cases have been published. Diagnosis was based on histology alone in 2 (2.1%) and microbiological evidence in 67 (69.8%), while no data on the diagnostic approach was reported in 27 (28.1%) patients. The most frequent pathogens were Rhizopus spp. (31.2%), followed by Mucor spp. (14.6%). The site of infection was predominantly rhino-orbital (38.5%, of which 43% also had central nervous system [CNS] involvement), followed by disseminated disease (22.1%). A complete response was achieved in 62 (64.6%), partial response in 7 (7.3%) patients, and stable disease in 1 (1%). Overall mortality was 24% (lacking data for three patients). In published case reports on posaconazole treatment for mucormycosis, the drug was frequently and successfully used in combination or as second line therapy.

Infections in Leukemia and Hematopoietic Stem Cell Transplantation

Infections are one of the most common complications in patients diagnosed with leukemia and serve as a major obstacle to treatment. Through the early 1970s, infections were the most common cause of death in patients diagnosed with acute leukemia, but improvement in treatment and supportive care over the past few decades, coupled with expanded prophylaxis and prevention regimens, have led to reduction in both the frequency and severity of infections. Regardless, due in part to an aging cancer population and the diversity of cancer treatments and procedures, infectious diseases remain a major cause of morbidity and mortality in patients with leukemia.

Mucormycosis caused by unusual mucormycetes, non-Rhizopus, -Mucor, and -Lichtheimia species

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.

Rapidly progressive cutaneous Rhizopus microsporus infection presenting as Fournier's gangrene in a patient with acute myelogenous leukemia

Members of the genus Rhizopus within the class Zygomycetes can cause devastating opportunistic infections. Cutaneous disease arising from direct inoculation of fungal spores has the potential to disseminate widely. Here, we describe a dramatic case of cutaneous Rhizopus infection involving the penis in a patient with acute myelogenous leukemia. Despite aggressive surgical debridement, systemic antifungal therapy, and donor lymphocyte infusion, the infection was ultimately fatal. This case illustrates the unique diagnostic and therapeutic challenges in the clinical management of cutaneous Rhizopus infection.

Mortality risk factors in patients with zygomycosis: a retrospective and multicentre study of 25 cases

AIM

To investigate mortality risk factors in patients with zygomycosis.

PATIENTS AND METHODS

Retrospective case history review of patients diagnosed with proven zygomicosis in 17 centres in Spain. We compared demographics and risk factors in patients who survived, and in those who died.

RESULTS

We identified twenty-five patients with proven zygomycosis. The primary site of infection was rhino-orbito-cerebral (28%) and disseminated (20%) or cutaneous/soft infections (20%) of the patients. Eleven patients (44%) received preemptive or empirical antifungal treatment; of these patients, 4 received liposomal amphotericin B, 1 received amphotericin B lipid complex, and 6 received other antifungals. The overall mortality rate was 72%. In the univariate analysis factors associated with an increased risk of death were the presence of a haematological malignancy (P=.03), neutropenia (P=.03) and monocytopenia (P=.008).

CONCLUSION

Our study supports previous research that has documented a high mortality rate among patients with invasive zygomycosis, especially among those with an underlying haematological malignancy, and the need for a rapid initiation of an effective antifungal treatment.

What are fungal infections?

Yeasts and moulds now rank amongst the 10 most frequently isolated pathogens in febrile patients with an impaired immune system. Fungi are mainly opportunistic pathogens that only invade the body if a severely weakened natural defense permits them to do so. Most factors facilitating an invasive fungal infection are unavoidable because they are directly connected to the underlying diseases as well as to their treatment.Modern aggressive treatment modalities jeopardize the defense mechanisms to an extent that even fungi with a low virulence may enter the body.