Real-time treatment guidelines: considerations during the Exserohilum rostratum outbreak in the United States

Update on diagnosis and treatment of fungal meningitis: lessons from recent outbreaks

PURPOSE OF REVIEW

Recently, fungal meningitis outbreaks have occurred in association with neuraxial and epidural anesthesia in immunocompetent patients. Herein, we describe the course of those outbreaks, their diagnosis, treatment, prognosis, and lessons learned.

RECENT FINDINGS

Two outbreaks of Fusarium solani meningitis during 2022-2023 were associated with epidural anesthesia in two distant cities in Mexico (Durango and Matamoros). The initial etiological agent identification was delayed due to insensitivity of cultures. A Fusarium solani qPCR was validated and positive in 38% cerebrospinal fluid (CSF) samples from Durango, while BD-Glucan allowed early diagnosis of the index case in Matamoros. Antifungal treatment with voriconazole and liposomal amphotericin B (L-AmB) was recommended. Overall mortality was 51%. Once the cause was confirmed, some patients received fosmanogepix.

SUMMARY

Fungal meningitis outbreaks due to filamentous fungi are usually associated with direct epidural inoculation. They result in severe presentations and high mortality. Early diagnosis should be suspected, BD-Glucan CSF testing screening is recommended. Aggressive antifungal treatment based on antifungal susceptibility testing should be administered as early as possible. The advent of molecular diagnostic methods and new antifungal drugs may allow for timely diagnosis and treatment, increasing the chances of survival.

Antifungal Resistance Profile of Fungal Isolates from Fungal Rhinosinusitis Patients: A Study from Tertiary Care Hospital

Objective  Fungal rhinosinusitis is on the rise worldwide and it is endemic especially in North India. The main purpose of this study was to determine the antifungal resistance profile of fungal isolates from the cases of fungal rhinosinusitis. Methods  Antifungal susceptibility testing of isolated fungi to fluconazole, amphotericin B, itraconazole, and voriconazole was determined by standard CLSI broth microdilution method. Results  Sixty-eight fungal isolates of Aspergillus spp . ( n  = 49), Rhizopus spp. ( n  = 9), Candida spp . ( n  = 4), Penicillium spp . ( n  = 2), Mucor spp . ( n  = 2), Bipolaris spp . ( n  = 1), and Alternaria spp . ( n  = 1) were obtained from 60 different clinical samples as exudate from nasal mucosa ( n  = 28), allergic mucin ( n  = 8), nasal lavage ( n  = 2), tissue biopsy from nasal polyps ( n  = 14), and intraoperative nasal mucosa ( n  = 8). Of the 68 isolates, 75% were resistant to fluconazole, 13.23% were resistant to itraconazole, 2.94% to amphotericin B, and none were resistant to voriconazole. Aspergillus flavus (5%) was the only fungi found resistant to amphotericin B, while against itraconazole, A. flavus (7.5%) and A. niger (100%) were found resistant. All the isolates of A. flavus , A. fumigatus , A. niger , and Penicillium spp. were resistant to fluconazole. Conclusion  Although amphotericin B stills remains to be the most effective drug, more prospective studies are needed for the requirement of knowledge of the sensitivity pattern for optimal treatment and reduction in morbidity in the long run.

Sinusitis caused by Exserohilum rostratum after cord blood transplantation for myelodysplastic syndrome: A case report and literature review

Invasive fungal disease is a serious infectious complication of allogeneic hematopoietic stem cell transplantation (HSCT). Exserohilum rostratum is a species causing phaeohyphomycosis, which rarely causes invasive disease in humans. We treated a case of sinusitis caused by E. rostratum after cord blood transplantation (CBT). A 60-year-old man with myelodysplastic syndrome, who had a medical history of an operation to correct deviation of the nasal septum, developed sinusitis caused by E. rostratum under prolonged profound neutropenia after a second CBT because of the graft rejection of the first transplantation. Liposomal amphotericin B improved the sinusitis. A literature review revealed nine reported cases of sinusitis caused by E. rostratum, including our case. Although five cases had severe neutropenia at onset (HSCT recipients, n = 2; aplastic anemia, n = 3), the remaining four had no preexisting immunosuppressive conditions. However, three of the four patients had preexisting nasal diseases with or without a history of surgery, as in our case. Excluding our case, the outcome was fatal in five neutropenic patients, whereas the four patients without neutropenia recovered. Although sinusitis caused by E. rostratum is rare, E. rostratum should be recognized as a possible pathogen causing sinusitis in highly immunosuppressed patients such as HSCT recipients. Preexisting nasal disease and/or nasal surgery could be risks for this infection.

Continuous intrathecal administration of liposomal amphotericin B for treatment of refractory Cryptococcus neoformans encephalitis: A case report

The aim of the present study was to investigate the treatment of refractory Cryptococcus neoformans encephalitis with continuous administration of liposomal amphotericin B (AmB). Liposomal AmB was administered to a 28-year-old male by intravenous injection, with daily increasing dosages up to 150 mg per day and combined use of fluconazole (0.4 g per day) and oral flucytosine tablets (1.5 g per day). Following 5 months of treatment, C. neoformans could still be detected in the ink stain of cerebrospinal fluid, but the patient could not tolerate a further increase in the dosage of liposomal AmB. Instead, continuous intrathecal administration of AmB through tube drainage on the lumbar cistern was used. A total dosage of 28 mg liposomal AmB was administered to the patient over the course of 1 month. The effect of AmB administered by intravenous injection was not as great as expected and the patient's tolerance was not good. However, the patient recovered following treatment by continuous intrathecal administration of AmB through tube drainage on the lumbar cistern for 1 month. This case suggests that continuous intrathecal administration of liposomal AmB should be considered for clinical treatment of refractory cryptococcal encephalitis.

The Carbohydrate Lectin Receptor Dectin-1 Mediates the Immune Response to Exserohilum rostratum

Dematiaceous molds are found ubiquitously in the environment and cause a wide spectrum of human disease, including infections associated with high rates of mortality. Despite this, the mechanism of the innate immune response has been less well studied, although it is key in the clearance of fungal pathogens. Here, we focus on Exserohilum rostratum, a dematiaceous mold that caused 753 infections during a multistate outbreak due to injection of contaminated methylprednisolone. We show that macrophages are incapable of phagocytosing Exserohilum Despite a lack of phagocytosis, macrophage production of tumor necrosis factor alpha is triggered by hyphae but not spores and depends upon Dectin-1, a C-type lectin receptor. Dectin-1 is specifically recruited to the macrophage-hyphal interface but not the macrophage-spore interface due to differences in carbohydrate antigen expression between these two fungal forms. Corticosteroid and antifungal therapy perturb this response, resulting in decreased cytokine production. In vivo soft tissue infection in wild-type mice demonstrated that Exserohilum provokes robust neutrophilic and granulomatous inflammation capable of thwarting fungal growth. However, coadministration of methylprednisolone acetate results in robust hyphal tissue invasion and a significant reduction in immune cell recruitment. Our results suggest that Dectin-1 is crucial for macrophage recognition and the macrophage response to Exserohilum and that corticosteroids potently attenuate the immune response to this pathogen.

In Vitro Activities of Eight Antifungal Drugs against a Global Collection of Genotyped Exserohilum Isolates

The in vitro susceptibilities of 24 worldwide Exserohilum isolates belonging to 10 species from human and environmental sources were determined for eight antifungal drugs. The strains were characterized by internal transcribed spacer (ITS) sequencing and amplified fragment length polymorphism fingerprinting. Posaconazole had the lowest geometric mean MIC (0.16 μg/ml), followed by micafungin (0.21 μg/ml), amphotericin B (0.24 μg/ml), itraconazole (0.33 μg/ml), voriconazole (0.8 μg/ml), caspofungin (1.05 μg/ml), isavuconazole (1.38 μg/ml), and fluconazole (15.6 μg/ml).

In vitro interactions between amphotericin B and hydrocortisone: potential implications for intrathecal therapy

Fungal meningitis remains a severe and often lethal infection requiring aggressive antifungal therapy and in refractory cases the use of intrathecal amphotericin B (AmB). Administration of amphotericin B by this method may result in clinically apparent adverse reactions such as paresthesias, radiculitis, or myelopathy. Coadministration of hydrocortisone is therefore often given in an attempt to avoid these effects; however, the potential consequences of this approach on fungal growth or on drug synergy/antagonism had not previously been assessed. We used the checkerboard titration broth microdilution method to analyze interactions by fractional inhibitory concentration indices (FICIs). The combination of amphotericin B and hydrocortisone resulted in synergy or indifference against all isolates (Candida, Cryptococcus, and Coccidioides) during in vitro testing at low concentrations. Antagonism was observed using higher hydrocortisone concentrations (those not observed in vivo) suggesting possible steric hindrance or binding to AmB may occur at doses unlikely to be present during clinical care. Concurrent hydrocortisone and AmB administration should not be avoided due to in vitro antagonism concerns.

Healthcare-associated outbreaks due to Mucorales and other uncommon fungi

BACKGROUND

Healthcare-associated outbreaks of fungal infections, especially with uncommon and emerging fungi, have become more frequent in the past decade.

MATERIALS AND METHOD

Here, we reviewed the history and definition of healthcare-associated outbreaks of uncommon fungal infections and discussed the principles of investigating, containing and treatment of these outbreaks.

RESULTS

In case of these uncommon diseases, occurrence of two or more cases in a short period is considered as an outbreak. Contaminated medical devices and hospital environment are the major sources of these outbreaks. Care must be taken to differentiate a real infection from colonization or contamination. Defining and identifying cases, describing epidemiologic feature of cases, finding and controlling the source of the outbreak, treating patients, and managing asymptomatic exposed patients are main steps for outbreak elimination. These fungal outbreaks are not only difficult to detect but also hard to treat. Early initiation of appropriate antifungal therapy is strongly associated with improved outcomes in infected patients. Choice of antifungal drugs should be made based on spectrum, pharmacodynamic and pharmacokinetic characteristics and adverse effects of available drugs. Combination antifungal therapy and surgical intervention may be also helpful in selected cases.

CONCLUSIONS

A multidisciplinary approach and close collaboration between all key partners are necessary for successful control of fungal outbreaks.

A five-year survey of dematiaceous fungi in a tropical hospital reveals potential opportunistic species

Dematiaceous fungi (black fungi) are a heterogeneous group of fungi present in diverse environments worldwide. Many species in this group are known to cause allergic reactions and potentially fatal diseases in humans and animals, especially in tropical and subtropical climates. This study represents the first survey of dematiaceous fungi in Malaysia and provides observations on their diversity as well as in vitro response to antifungal drugs. Seventy-five strains isolated from various clinical specimens were identified by morphology as well as an internal transcribed spacer (ITS)-based phylogenetic analysis. The combined molecular and conventional approach enabled the identification of three classes of the Ascomycota phylum and 16 genera, the most common being Cladosporium, Cochliobolus and Neoscytalidium. Several of the species identified have not been associated before with human infections. Among 8 antifungal agents tested, the azoles posaconazole (96%), voriconazole (90.7%), ketoconazole (86.7%) and itraconazole (85.3%) showed in vitro activity (MIC ≤1 µg/mL) to the largest number of strains, followed by anidulafungin (89.3%), caspofungin (74.7%) and amphotericin B (70.7%). Fluconazole appeared to be the least effective with only 10.7% of isolates showing in vitro susceptibility. Overall, almost half (45.3%) of the isolates showed reduced susceptibility (MIC >1 µg/mL) to at least one antifungal agent, and three strains (one Pyrenochaeta unguis-hominis and two Nigrospora oryzae) showed potential multidrug resistance.

Lessons learned in the multistate fungal infection outbreak in the United States

PURPOSE OF REVIEW

The recent outbreak of fungal meningitis related to contaminated methylprednisolone acetate injections represents an important cause of morbidity and continues to be a significant public health problem in the United States.

RECENT FINDINGS

As of August 2013, there have been 749 cases and 63 deaths in 20 states associated with epidemic fungal meningitis, most of these because of Exserohilum rostratum. Clinical experience in managing these cases has grown dramatically in the last several months; most patients require at least 6 months of antifungal therapy for complicated disease. Most patients are treated with voriconazole, with or without liposomal amphotericin B, for central nervous system and paraspinal complications of the disease. For disease involving the sacroiliac and peripheral joints, voriconazole alone has been preferred. MRI spine imaging has identified several cases of asymptomatic disease, suggesting an aggressive diagnostic approach to exposed asymptomatic patients. Mortality remains low (<10%), but morbidity relating to persistent symptoms and treatment-associated toxicity is high.

SUMMARY

The ongoing fungal meningitis epidemic demonstrates an important achievement for the public health community. Important questions remain relating to the diagnosis, management, and long-term outcomes of these patients. Important research questions pertaining to specific risks influencing disease manifestations remain unanswered.

Exserohilum infections: review of 48 cases before the 2012 United States outbreak

Exserohilum species are soilborne fungi that have been uncommon causes of human disease. The ongoing outbreak in the United States warrants improved understanding of this pathogen. We systematically reviewed all cases of Exserohilum spp. infections published before the outbreak in 2012 in order to provide a better understanding of the organism and its wider spectrum of human disease. Cases of Exserohilum infections were retrieved by searching PubMed. Demographic data, underlying conditions, microbiology, clinical manifestations, therapy, and outcome were recorded and analyzed. Forty-eight evaluable cases were identified from 1975 to 2012. The number of reported cases increased more than twofold during the study period (P < 0.01). Most cases occurred in the southern United States, India, and Israel. Median age of patients was 25 years, with a male predominance. Most infections were due to E. rostratum (60.4%), followed by E. longirostratum (6.3%) and E. mcginnisii (2%), while 31.3% were unidentified species. The most frequent underlying conditions were immunosuppression (27.2%), trauma (16.6%), and atopy (12.5%). Exserohilum disease manifested as systemic (73%), cutaneous (25%), corneal (16.7%), and subcutaneous (10.4%) infection. Antifungal therapy consisted mainly of amphotericin B (44%) alone or combined with a triazole. Surgery was used in 48% of cases and was combined with antifungal therapy in 31%. The all-cause mortality was 23%, which was higher in patients with preexisting immunosuppression (56.2%; odds ratio 15.4; 95% confidence interval, 2.7-88.6). This review of the pre-outbreak reported cases highlights several aspects of epidemiology, clinical presentation, risk factors, and management of this unusual pathogen.

CNS Mold Infections

Mold infections of the central nervous system (CNS) present as abscesses, infarcts, hemorrhages, and, less commonly, meningitis. These invasive infections are difficult both to identify and to eradicate given low-sensitivity diagnostics and high-toxicity, low-efficacy antifungal therapies, hence resulting in high rates of morbidity and mortality. Herein, the recent literature on CNS mold infections is reviewed, and updates in diagnosis and management are discussed.

Preliminary laboratory report of fungal infections associated with contaminated methylprednisolone injections

In September 2012, the Centers for Disease Control and Prevention (CDC) initiated an outbreak investigation of fungal infections linked to injection of contaminated methylprednisolone acetate (MPA). Between 2 October 2012 and 14 February 2013, the CDC laboratory received 799 fungal isolates or human specimens, including cerebrospinal fluid (CSF), synovial fluid, and abscess tissue, from 469 case patients in 19 states. A novel broad-range PCR assay and DNA sequencing were used to evaluate these specimens. Although Aspergillus fumigatus was recovered from the index case, Exserohilum rostratum was the primary pathogen in this outbreak and was also confirmed from unopened MPA vials. Exserohilum rostratum was detected or confirmed in 191 specimens or isolates from 150 case patients, primarily from Michigan (n=67 patients), Tennessee (n=26), Virginia (n=20), and Indiana (n=16). Positive specimens from Michigan were primarily abscess tissues, while positive specimens from Tennessee, Virginia, and Indiana were primarily CSF. E. rostratum antifungal susceptibility MIC50 and MIC90 values were determined for voriconazole (1 and 2 μg/ml, respectively), itraconazole (0.5 and 1 μg/ml), posaconazole (0.5 and 1 μg/ml), isavuconazole (4 and 4 μg/ml), and amphotericin B (0.25 and 0.5 μg/ml). Thirteen other mold species were identified among case patients, and four other fungal genera were isolated from the implicated MPA vials. The clinical significance of these other fungal species remains under investigation. The laboratory response provided significant support to case confirmation, enabled linkage between clinical isolates and injected vials of MPA, and described significant features of the fungal agents involved in this large multistate outbreak.

Fungal disease following contaminated steroid injections: Exserohilum is ready for its close-up

This Commentary highlights the article by Ritter et al. that reported the pathology associated with the recent fungal outbreak associated with contaminated methylprednisolone acetate injections.