Successful treatment of an invasive fungal infection caused by Talaromyces sp. with voriconazole.

Invasive fungal infections (IFI) are on the rise due to increasing numbers of immunosuppressed and critically ill patients. A malignant-looking pulmonary nodule in an immunosuppressed patient may indeed be caused by a fungal organism. We report a patient, who was eventually diagnosed with an IFI caused by an agent of hyalohyphomycosis, Talaromyces sp. determined via molecular methods and succesfully treated with voriconazole.

Introduction

The incidence of invasive fungal infections (IFI) has been on the rise due to increasing numbers of immunocompromised or severely ill patients. This rise in incidence is accompanied by a broadening range of fungal species causing potentially lethal disease [1]. The subject of this report had a solitary pulmonary nodule, which was initially suspected to be of malignant origin but eventually was confirmed to be of fungal origin. To our knowledge, this is the first report of an IFI caused by Talaromyces species (sp.) that is successfully treated with voriconazole.

Case

A 61-year-old male was admitted to our clinic (day 0) with complaints of right pleuritic chest pain and dyspnea on exertion during the past two weeks. He reported increased sputum production and purulence accompanied by cough and fever. He had been diagnosed with rheumatoid arthritis (RA) and chronic obstructive pulmonary disease (COPD) five years ago. His RA was under control with leflunamide 20 mg per day and methylprednisolone 4 mg per day. He used inhaled corticosteroids and bronchodilators for COPD.

On day −150, his rheumatologist had ordered a computerized chest tomography (CT) scan, which revealed a 12-mm nodule with spicular borders in the left lower lobe (Fig. 1). On day −30, this nodule was biopsied by interventional radiology for exclusion of malignancy. As the patient did not have any symptoms compatible with an infectious process at that time, samples were sent for histopathological examination only. Malignancy was ruled out, but the pathology report described a suppurative, granulomatous inflammation around fungal hyphal elements with the presumptive diagnosis of a candida infection (Fig. 2).

Fig. 1

A 12-mm sub-solid nodule with spicular borders in left lower lobe (day -150).

Fig. 2

Grocott's methenamine silver stain; (a) ×100 magnification, (b) ×400 magnification. Suppurative granulamatous inflammation with fungal hyphal elements (day −30).

On admission, his body temperature was 38 °C, his pulse rate was 90 beats per minute, respiratory rate was 20 per minute and blood pressure was 130/70 mmHg. Oxygen saturation was 98% on room air. Bilateral rhonchi were heard. Remainder of the physical examination was unremarkable. A repeat thoracic CT taken on day 0 revealed persistence of the nodule in left lower lobe, while there was a new loculated pleural collection adjacent to medial right lower lobe (Fig. 3a). Fluconazole (400 mg i.v. once daily) was started with the presumptive diagnosis of candida pneumonia, based on histopathological report.

Fig. 3

Thoracic CT imaging at day 0 (a), day +17 (b) and day +82 (c). Image (a) shows left lower lobe nodule and right pleural collection at day 0. Image (b) shows progression of left lower lobe nodule into a consolidation and partial regression of right pleural collection at day +17. Image (c) shows 80% reduction in size of left lower lobe nodule and complete regression of right pleural collection.

On day +4, right pleural collection was drained by interventional radiology. Samples sent from this collection were negative for any microbiological growth, but microscopic examination showed abundant polymorphonuclear leucocyte (PMNL) infiltration with a negative Gram stain suggesting abscess formation. Ampicillin-sulbactam (2 g i.v. four times a day) was added to treatment. On day +14, right pleural collection was drained for a second time by thoracic surgery. Samples sent from this collection were again negative for any microbiologic growth, but still showed abundant PMNL infiltration. A thoracic CT taken on day +17 revealed partial regression of right pleural collection, while left lower lobe nodule progressed into a focal nodular consolidation (Fig. 3b). We concluded that fluconazole failed. Antifungal treatment was changed to caspofungin (70 mg i.v. loading and 50 mg i.v. maintenance once daily) based on the assumptions of fluconazole unresponsive candida pneumonia or possibility of a mold infection. On day +26, antifungal treatment was switched to voriconazole (400 mg i.v. twice daily loading and 200 mg i.v. twice daily maintenance), since an oral agent would be preferable during the prolonged treatment period.

A control thoracic CT taken on day +31 revealed 50% regression in size of nodule and the patient was discharged with voriconazole 200 mg per oral twice daily. Another control CT taken on day +82 revealed almost complete regression of lesion (Fig. 3c) and voriconazole treatment was stopped on day +99. Patient was given a biological agent, abatacept for RA on day +177 and completed a total of nine monthly injections without any infectious complications.

Later for identification of the fungus, genomic sequencing from paraffin blocks was conducted. This involved deparaffinization of tissue sample performed as per the protocol described by Bialek et al. [2], and genomic DNA extraction using the CTAB method as described by Fraczek et al. [3]. The fungal ITS region was amplified by PCR using Primers ITS1 and ITS4 [4] and sequenced in both directions by dideoxy chain termination/ cycle sequencing on an ABI 3730XL sequencing machine (Eurofins MWG Operon Ebersberg, Germany). Sequences were compared to those available in the CBS-KNAW Fungal Biodiversity Centre database (http://www.cbs.knaw.nl) using the Pairwise Sequence Alignment tool. The ITS sequence demonstrated 100% identity to Talaromyces sp. (GenBank Accession no. JX315670, base pair match 478/478) genus. Although the top species identity was Talaromyces stollii (GenBank Accession no. JX965246.1, base pair match 478/478), the ITS region is inadequate to definitively distinguish to this level.

Discussion

Our case highlights the need for microbiological examination of solitary pulmonary nodules detected in immunosuppressed patients. Although the major differential diagnosis is malignancy for such nodules, fungal organisms may well be the etiological agent, particularly in immunosuppressed patients. Biopsy is usually performed to rule out malignancy; however, once the specimen is placed in formalin, the opportunity for culture is lost, which is the gold standard in identification of fungal element. As in our case, when culture opportunity is lost or there is no growth in culture, a molecular approach may be quite useful in identification of fungal species.

Histopathological examination is crucial to demonstrate invasiveness of infection, but morphological identification of fungal species should be avoided as it may misidentify the fungal element [5]. It has been reported that in at least 20% of cases, misclassifications of fungal organisms occur in histopathological examination [6]. Yeast-mold differentiation is important for empirical and definitive treatment of fungal infections as it affects the choice of antifungal agent. In our case, based on the presumptive histopathological diagnosis of candida infection, a therapeutic trial with fluconazole was carried out as it has both parenteral and oral formulations, is much cheaper than the other antifungal drugs and has fewer side effects. However, patient’s condition did not improve which necessitated switching to an extended-spectrum antifungal agent. An echinocandin or voriconazole are possible alternatives in this case, although the latter has an oral formulation making it ideal for prolonged outpatient therapy. In our case, voriconazole was well-tolerated by the patient and led to total cure of mold infection after two and a half months of treatment.

Using DNA sequencing, fungal element was later identified as a mold belonging to Talaromyces sp., which is an agent of hyalohyphomycoses. This finding also explained the unresponsiveness to fluconazole that we initially observed. To the best of our knowledge, this is the first report of an IFI caused by Talaromyces sp. Our case shows that Talaromyces sp. is the latest addition to a growing list of rare light-colored (hyaline) molds causing serious infection [1,7].

Biological therapies for immune-mediated inflammatory diseases appear to carry increased infectious risks [8]. Abatacept functions as a T-cell co-stimulation modulator. Although it carries a labeled warning regarding the risk of pulmonary infections, in clinical trials the incidence of serious infection appeared lower than that encountered with other biological agents [9]. In our case, although secondary prophylaxis was not administered, there was no recurrence of IFI with abatacept. More studies are needed to determine whether abatacept can safely be given without secondary prophylaxis in patients with proven IFI.

Clinicians taking care of immunocompromised patients should carry the suspicion that a fungal agent might play a role in a variety of disease settings, thus remember to request for microbiological as well as histopathological examination.

Conflict of interest

There are none relevant to this case.