The significance of blood cultures positive for emerging saprophytic moulds in cancer patients

Myocarditis and brain abscess caused by disseminated Scedosporium boydii infection

Scedosporium spp. is a fungal species documented as the cause of infections involving the lungs, brain, and other organ systems in both immunocompetent and immunocompromised individuals. Many cases of this type of fungal infection occurring in immunocompetent patients are subsequent to traumatic injury or drowning events in or near waters containing the fungi. Infection commonly involves the lungs. Rarely, it has been shown to cause disease in the endocardium, but there is even less documentation of the fungi invading the myocardium and causing myocarditis. In this report, we present a case of disseminated Scedosporium boydii infection in a 52-year-old male patient without any known risk factors. He presented with acute onset chest pain and dyspnea accompanied by bilateral lower extremity edema. He was found to have new onset heart failure with reduced ejection fraction, and his hospital course was complicated by pneumonia, disseminated intravascular coagulation (DIC), and brain abscess formation. Multiple blood cultures failed to reveal the source of the infection. At autopsy, septated branching hyphae were identified invading both the myocardium and the cortical brain tissue. DNA sequencing revealed the fungal organisms to be Scedosporium boydii. This case reinforces the importance of autopsies in the clinical setting. It not only established the definitive diagnosis of an unexpected fungal infection, but it also helped to recognize new clinical and pathologic features of this particular fungal organism.

In vivo efficacy of olorofim against systemic scedosporiosis and lomentosporiosis

Clinically relevant members of the Scedosporium/Pseudallescheria species complex and Lomentospora prolificans are generally resistant against currently available systemic antifungal agents in vitro and the infection due to these species is difficult to treat. We studied the in vivo efficacy of a new fungicidal agent olorofim (formerly F901318) against scedosporiosis and lomentosporiosis in neutropenic animals. Cyclophosphamide immunosuppressed CD-1 mice infected by Scedosporium apiospermum, Pseudallescheria boydii (Scedosporium boydii) and Lomentospora prolificans were treated by intraperitoneal administration of olorofim (15 mg/kg every 8 h for 9 days). The efficacy of olorofim treatment was assessed by the survival rate at 10 days post infection, levels of serum (1-3)-β-d-glucan (BG), histopathology, and fungal burden of kidneys 3 days post infection. Olorofim therapy significantly improved survival compared to the untreated controls; 80%, 100% and 100% of treated mice survived infection by Scedosporium apiospermum, Pseudallescheria boydii, and Lomentospora prolificans, respectively while less than 20% of the control mice (PBS-treated) survived at 10 days post infection. In the olorofim-treated neutropenic CD-1 mice infected with all three species, serum BG levels were significantly suppressed and fungal DNA detected in the target organs was significantly lower than controls. Furthermore, histopathology of kidneys revealed no or only few lesions with hyphal elements in the olorofim-treated mice, while numerous fungal hyphae were present in control mice. These results indicate olorofim to be a promising therapeutic agent for systemic scedosporiosis/lomentosporiosis, a devastating emerging fungal infection difficult to treat with currently available antifungals.

Recognition of Diagnostic Gaps for Laboratory Diagnosis of Fungal Diseases: Expert Opinion from the Fungal Diagnostics Laboratories Consortium (FDLC)

Fungal infections are a rising threat to our immunocompromised patient population, as well as other nonimmunocompromised patients with various medical conditions. However, little progress has been made in the past decade to improve fungal diagnostics. To jointly address this diagnostic challenge, the Fungal Diagnostics Laboratory Consortium (FDLC) was recently created. The FDLC consists of 26 laboratories from the United States and Canada that routinely provide fungal diagnostic services for patient care. A survey of fungal diagnostic capacity among the 26 members of the FDLC was recently completed, identifying the following diagnostic gaps: lack of molecular detection of mucormycosis; lack of an optimal diagnostic algorithm incorporating fungal biomarkers and molecular tools for early and accurate diagnosis of Pneumocystis pneumonia, aspergillosis, candidemia, and endemic mycoses; lack of a standardized molecular approach to identify fungal pathogens directly in formalin-fixed paraffin-embedded tissues; lack of robust databases to enhance mold identification with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry; suboptimal diagnostic approaches for mold blood cultures, tissue culture processing for Mucorales, and fungal respiratory cultures for cystic fibrosis patients; inadequate capacity for fungal point-of-care testing to detect and identify new, emerging or underrecognized, rare, or uncommon fungal pathogens; and performance of antifungal susceptibility testing. In this commentary, the FDLC delineates the most pressing unmet diagnostic needs and provides expert opinion on how to fulfill them. Most importantly, the FDLC provides a robust laboratory network to tackle these diagnostic gaps and ultimately to improve and enhance the clinical laboratory's capability to rapidly and accurately diagnose fungal infections.

Fungaemia in haematological malignancies: SEIFEM-2015 survey

BACKGROUND

Fungal infections are still a relevant challenge for clinicians involved in the cure of patients with cancer. We retrospectively reviewed charts of hospitalized patients with haematological malignancies (HMs), in which a documented fungaemia was diagnosed between January 2011 and December 2015 at 28 adult and 6 paediatric Italian Hematology Departments.

METHODS

During the study period, we recorded 215 fungal bloodstream infections (BSI). Microbiological analyses documented that BSI was due to moulds in 17 patients (8%) and yeasts in 198 patients (92%), being Candida spp identified in 174 patients (81%).

RESULTS

Mortality rates were 70% and 39% for mould and yeast infections, respectively. Infection was the main cause of death in 53% of the mould and 18% of the yeast groups. At the multivariate analysis, ECOG ≥ 2 and septic shock were significantly associated with increased mortality, and removal of central venous catheter (CVC) survival was found to be protective. When considering patients with candidemia only, ECOG ≥ 2 and removal of CVC were statistically associated with overall mortality.

CONCLUSIONS

Although candidemia represents a group of BSI with a good prognosis, its risk factors largely overlap with those identified for all fungaemias, even though the candidemia-related mortality is lower when compared to other fungal BSI. Management of fungal BSI is still a complex issue, in which both patients and disease characteristics should be focused to address a personalized approach.

Comparison Between Etest and Broth Microdilution Methods for Testing Itraconazole-Resistant Aspergillus fumigatus Susceptibility to Antifungal Combinations

The checkerboard broth microdilution assay (BMD) is the most frequently used method for the in vitro evaluation of drug combinations. However, its use to evaluate the effect of antifungal drugs on filamentous fungi is sometimes associated with endpoint-reading difficulties, and different degrees of interaction are assigned to the same drug combination. We evaluated combinations of the azoles, itraconazole, posaconazole, and voriconazole, with the echinocandins, anidulafungin, caspofungin, and micafungin, against 15 itraconazole-resistant Aspergillus fumigatus clinical strains via the checkerboard BMD and Etest assay. Readings after 24 and 48 h, considering the two reading endpoints, the minimum inhibitory concentration (MIC) and minimum effective concentration (MEC), were performed for both methods. Our results showed that the correlation coefficients between the BMD and Etest methods were quite diverse to the drug combinations tested. The highest correlation coefficients of the Etest with the BMD assays (MEC and MIC reading) were the Etest-MIC reading at 24 h and the Etest-MEC reading at 48 h. Improvements in experimental conditions may increase the correlation between the two methods and ensure that Etest assay can be safely used in the evaluation of antifungal combinations against Aspergillus species.

Molecular and nonmolecular diagnostic methods for invasive fungal infections

Invasive fungal infections constitute a serious threat to an ever-growing population of immunocompromised individuals and other individuals at risk. Traditional diagnostic methods, such as histopathology and culture, which are still considered the gold standards, have low sensitivity, which underscores the need for the development of new means of detecting fungal infectious agents. Indeed, novel serologic and molecular techniques have been developed and are currently under clinical evaluation. Tests like the galactomannan antigen test for aspergillosis and the β-glucan test for invasive Candida spp. and molds, as well as other antigen and antibody tests, for Cryptococcus spp., Pneumocystis spp., and dimorphic fungi, have already been established as important diagnostic approaches and are implemented in routine clinical practice. On the other hand, PCR and other molecular approaches, such as matrix-assisted laser desorption ionization (MALDI) and fluorescence in situ hybridization (FISH), have proved promising in clinical trials but still need to undergo standardization before their clinical use can become widespread. The purpose of this review is to highlight the different diagnostic approaches that are currently utilized or under development for invasive fungal infections and to identify their performance characteristics and the challenges associated with their use.

Fungal infection of the colon

Fungi are pathogens that commonly infect immunocompromised patients and can affect any organs of the body, including the colon. However, the literature provides limited details on colonic infections caused by fungi. This article is an intensive review of information available on the fungi that can cause colon infections. It uses a comparative style so that its conclusions may be accessible for clinical application.

Identifying the emerging human pathogen Scedosporium prolificans by using a species-specific monoclonal antibody that binds to the melanin biosynthetic enzyme tetrahydroxynaphthalene reductase

The dematiaceous (melanized) fungus Scedosporium prolificans is an emerging and frequently fatal pathogen of immunocompromised humans and which, along with the closely related fungi Pseudallescheria boydii, Scedosporium apiospermum and S. aurantiacum in the Pseudallescheria-Scedosporium complex, is a contributing aetiology to tsunami lung and central nervous system infections in near-drowning victims who have aspirated water laden with spores. At present, the natural habitat of the fungus is largely unknown, and accurate detection methods are needed to identify environmental reservoirs of infectious propagules. In this study, we report the development of a monoclonal antibody (mAb) (CA4) specific to S. prolificans, which does not cross-react with closely related fungi in the Pseudallescheria-Scedosporium complex or with a wide range of mould and yeast species pathogenic to humans. Using genome sequencing of a soil isolate and targeted gene disruption of the CA4 antigen-encoding gene, we show that mAb CA4 binds to the melanin-biosynthetic enzyme tetrahydroxynaphthalene reductase. Enzyme-deficient mutants produce orange-brown or green-brown spore suspensions compared with the black spore suspension of the wild-type strain. Using mAb CA4 and a mAb (HG12) specific to the related fungi P. boydii, P. apiosperma, S. apiospermum and S. aurantiacum, we demonstrate how the mAbs can be used in combination with a semiselective isolation procedure to track these opportunistic pathogens in environmental samples containing mixed populations of human pathogenic fungi. Specificity of mAb CA4 was confirmed by sequencing of the internally transcribed spacer 1 (ITS1)-5.8S-ITS2 rRNA-encoding regions of fungi isolated from estuarine muds.

Immunodetection of fungal and oomycete pathogens: established and emerging threats to human health, animal welfare and global food security

Filamentous fungi (moulds), yeast-like fungi, and oomycetes cause life-threatening infections of humans and animals and are a major constraint to global food security, constituting a significant economic burden to both agriculture and medicine. As well as causing localized or systemic infections, certain species are potent producers of allergens and toxins that exacerbate respiratory diseases or cause cancer and organ damage. We review the pathogenic and toxigenic organisms that are etiologic agents of both animal and plant diseases or that have recently emerged as serious pathogens of immunocompromised individuals. The use of hybridoma and phage display technologies and their success in generating monoclonal antibodies for the detection and control of fungal and oomycete pathogens are explored. Monoclonal antibodies hold enormous potential for the development of rapid and specific tests for the diagnosis of human mycoses, however, unlike plant pathology, their use in medical mycology remains to be fully exploited.

Uncommon mold infections in hematological patients: epidemiology, diagnosis and treatment

Invasive fungal diseases continue to be an important cause of morbidity and mortality in immunosuppressed patients. This is of particular interest, since the progress we made in the treatment of underlying malignancies has led to an increase of the number of persons 'at high risk'. During the last few years, several changes in clinical practice in hematology (new immunosuppressants, hematopoietic stem cell transplants) have influenced the epidemiology of invasive fungal diseases; in particular, cases due to some uncommon etiologic agents are being increasingly reported, making it even more urgent to reconsider differential diagnoses in high-risk patients. A better understanding of epidemiology, risk factors and prognosis appears to be crucial to analyze prevention and diagnostic strategies, as well as to guarantee an early and adequate treatment.

Rare opportunistic (non-Candida, non-Cryptococcus) yeast bloodstream infections in patients with cancer

BACKGROUND

Rare opportunistic (non-Candida, non-Cryptococcus) yeast bloodstream infections (ROYBSIs) are rare, even in cancer patients.

METHODS

We retrospectively reviewed all episodes of ROYBSIs occurring from 1998 to 2010 in our cancer center.

RESULTS

Of 2984 blood cultures positive for Candida and non-Candida yeasts, 94 (3.1%) were positive for non-Candida yeasts, representing 41 ROYBSIs (incidence, 2.1 cases/100,000 patient-days). Catheter-associated fungemia occurred in 21 (51%) patients. Breakthrough ROYBSIs occurred in 20 (49%) patients. The yeast species distribution was Rhodotorula in 21 (51%) patients, Trichosporon in 8 (20%) patients, Saccharomyces cerevisiae in 8 (20%) patients, Geotrichum in 2 (5%) patients, Pichia anomala, and Malassezia furfur in 1 patient each. All tested Trichosporon, Geotrichum, and Pichia isolates were azole-susceptible, whereas the Rhodotorula isolates were mostly azole-resistant. We noted echinocandin nonsusceptibility (minimal inhibitory concentration ≥ 2 mg/L) in all but the S. cerevisiae isolates. Most of the isolates (28/33 [85%]) were susceptible to amphotericin B. The mortality rate in all patients at 30 days after ROYBSIs diagnosis was 34%. Multivariate survival analysis revealed increased risk of death in patients with S. cerevisiae infections (hazard ratio, 3.7), Geotrichum infections (hazard ratio, 111.3), or disseminated infections (hazard ratio, 33.4) and reduced risk in patients who had catheter removal (hazard ratio, 0.1).

CONCLUSIONS

ROYBSIs are uncommon in patients with cancer, and catheters are common sources of them. Half of the ROYBSIs occurred as breakthrough infections, and in vitro species-specific resistance to echinocandins and azoles was common. Disseminated infections resulted in the high mortality rate.

Emerging moulds: epidemiological trends and antifungal resistance

Invasive fungal infections (IFIs) are associated with high morbidity and mortality in immunocompromised patients. Although Aspergillus spp. remain an important cause of IFI, other moulds such as Fusarium spp., dematiaceous fungi and Mucorales have become increasingly prevalent among this patient population. Diagnosis and treatment of invasive mould infections remain a challenge. Because of the poor prognosis associated with IFIs, understanding the activity, efficacy and limitations of the available drugs is critical to select the appropriate antifungal agent on an individualised basis.

Molds: hyalohyphomycosis, phaeohyphomycosis, and zygomycosis

Emerging fungi previously thought to be nonpathogenic are now recognized as playing a significant role in the increased incidence of invasive fungal disease. This change in the epidemiology of invasive fungal infections (IFIs) has occurred in the era of aggressive new therapies for hematopoietic stem cell transplantation and other malignancies that lead to profound immunosuppression for longer durations and has extended the survival of these critically ill patients. The significant morbidity and mortality associated with these infections is not only related to the host populations but to delayed recognition and diagnosis and high rates of resistance in some of these emerging pathogens to standard antifungal therapies.

Fatal Trichoderma harzianum infection in a leukemic pediatric patient

We report the repeated isolation for Trichoderma.harzianum, a rare opportunistic pathogen from three sets of each of the following clinical samples; blood serum, skin lesions, sputum and throat of a pediatric ALL patient with neutropenia. The definition of invasive fungal infection requires evidence of the presence of fungal elements in tissue samples, in addition to the isolation of suspected etiologic agent in culture. However, invasive procedures are not always applicable due to several factors, as for example in our case, the poor general status of the individual patient or thrombocytopenia. The present paper also emphasizes the problems encountered in obtaining appropriate samples and diagnosing invasive fungal disease in immunocompromised patient populations, including those with hematological malignancy. Three cases involving T. harzianum, including this one, have been described thus far in the literature. All were fatal and the fungus was resistant to antifungal therapy. A critical review of the other two cases of Trichoderma infections in humans is provided.

Tracking the emerging human pathogen Pseudallescheria boydii by using highly specific monoclonal antibodies

Pseudallescheria boydii has long been known to cause white grain mycetoma in immunocompetent humans, but it has recently emerged as an opportunistic pathogen of humans, causing potentially fatal invasive infections in immunocompromised individuals and evacuees of natural disasters, such as tsunamis and hurricanes. The diagnosis of P. boydii is problematic since it exhibits morphological characteristics similar to those of other hyaline fungi that cause infectious diseases, such as Aspergillus fumigatus and Scedosporium prolificans. This paper describes the development of immunoglobulin M (IgM) and IgG1 kappa-light chain monoclonal antibodies (MAbs) specific to P. boydii and certain closely related fungi. The MAbs bind to an immunodominant carbohydrate epitope on an extracellular 120-kDa antigen present in the spore and hyphal cell walls of P. boydii and Scedosporium apiospermum. The MAbs do not react with S. prolificans, Scedosporium dehoogii, or a large number of clinically relevant fungi, including A. fumigatus, Candida albicans, Cryptococcus neoformans, Fusarium solani, and Rhizopus oryzae. The MAbs were used in immunofluorescence and double-antibody sandwich enzyme-linked immunosorbent assays (DAS-ELISAs) to accurately differentiate P. boydii from other infectious fungi and to track the pathogen in environmental samples. Specificity of the DAS-ELISA was confirmed by sequencing of the internally transcribed spacer 1 (ITS1)-5.8S-ITS2 rRNA-encoding regions of environmental isolates.

Infection with Scedosporium apiospermum and S. prolificans, Australia

S. prolificans has become a major pathogen in immunocompromised patients.

Scedosporium apiospermum and S. prolificans are fungi of increasing clinical importance, particularly in persons with underlying diseases. We reviewed the records of 59 patients in Australia from whom Scedosporium spp. were isolated from June 30, 1997, through December 31, 2003. S. apiospermum was isolated predominantly from the respiratory tracts of 28 of 31 patients with underlying lung diseases and resulted in 2 infections and 1 death. The annual number of S. apiospermum isolates remained constant. S. prolificans was isolated from 28 patients only after November 1999. Eight patients with acute myeloid leukemia or hematopoietic stem cell transplants had invasive infection; 4 had fungemia and 6 died from infection. S. prolificans caused locally invasive infection in 2 immunocompetent patients and was found in the respiratory tract of 18 patients with underlying respiratory disease but did not cause fungemia or deaths in these patients. Scedosporium spp. showed distinct clinical and epidemiologic features.

High-dose caspofungin combination antifungal therapy in patients with hematologic malignancies and hematopoietic stem cell transplantation

Pneumocandins have concentration-dependent antifungal activity and higher dose of caspofungin (HD-CAP) in combination with other licensed antifungal therapy (OLAT) may improve response. Thirty-four patients who received HD-CAP were compared with 63 patients who received standard dose (SD)-CAP. There were no differences between the groups in either patient or disease characteristics. Significantly more patients in the HD-CAP arm had extrapulmonary infections (29 vs 8% in SD group; P=0.0053), and non-Aspergillus species infection (21 vs 6%; P=0.05) and had received prior antifungal therapy (71 vs 33%; P=0.0004). No serious adverse reactions were noted in patients receiving HD- or SD-CAP therapy. Twelve weeks after treatment commenced 44% had a complete or partial response compared with 29% in SD-CAP group (P=0.1). Logistic regression analysis showed a significant probability of a favorable outcome at 12 weeks in patients who received HD-CAP (OR 3.066, 95% CI, 1.092-8.61; P=0.033). This may in part reflect higher number of patients in HD group had received granulocyte-macrophage colony-stimulating factor (41 vs 14% in SD group; P=0.04) and/or interferon gamma (26 vs 5% in SD group; P=0.003) immune enhancement. Further studies are needed to evaluate efficacy of HD-CAP in severely immunosuppressed cancer patients with invasive fungal infections.

Scedosporium Infection in a Tertiary Care Cancer Center: A Review of 25 Cases from 1989-2006

We reviewed the records of patients with cancer who had Scedosporium infection (due to Scedosporium apiospermum and Scedosporium prolificans in 21 and 4 patients, respectively). The incidence of Scedosporium infection increased from 0.82 cases per 100,000 patient-inpatient days (in 1993-1998) to 1.33 cases per 100,000 patient-inpatient days (in 1999-2005). Cases of S. prolificans infection occurred only after 2000. Dissemination occurred in 16 patients (64%). The 12-week mortality rates were 70% and 100% for S. apiospermum and S. prolificans infection, respectively.

The Changing Face of Fungal Infections in Health Care Settings

As strategies to prevent invasive fungal infections among both hospitalized and nonhospitalized patients have evolved, the epidemiology of these infections has changed. Several unique features of select Candida species and molds have facilitated the emergence of these pathogens as more-common causes of infection than in previous years. In this context, the changing pathogen profiles, unique antifungal susceptibilities, and approaches to treatment are outlined.