Introduction

Opportunistic fungal infections represent one of the most frequent causes of morbidity, and mortality in immunocompromised patients. The most common fungal pathogens are Candida, Aspergillus, and Rhizomucor species. Geotrichum capitatum (formerly known as Blastoschizomyces capitatus, Trichosporon capitatus) is a rare pathogen in immunocompromised host. The mycosis caused by this fungal agent is often associated with multiorgan involvement and fatal outcome [1, 2]. According to the MEDLINE database in English language, 132 cases of B. capitatus infection have been reported during 1966–2008 [1–33]. Musculoskeletal involvement has been presented in six of them: mandibular osteomyelitis in one and spondylodiscitis in five patients [1, 3–7] (Table 1). We presented here another case of spondylodiscitis caused by B. capitatus, which is documented first in Turkey in a patient with colon adenocarcinoma with liver metastases and reviewed the other cases.

Table 1 Features of cases with osteoarticular infection due to Blastoschizomyces capitatus
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Case report

A 65-year-old man was admitted to our clinic with lumbar pain and weakness on both of his legs in January 2003. Before admission to our clinic, he had undergone sigmoid colon resection and, colostomy operation due to colon adenocarcinoma. His colostomy has surgically been corrected in September 2001. Ileostomy was closed in December 2001 and antineoplastic chemotherapy with 5-fluorouracil for colon adenocarcinoma was started in January 2002.

His complaints of lumbar pain developed in May 2002. At this time, upper abdominal magnetic resonance imaging (MRI) had been performed and hypointense pathologic signals on third and fourth lumbar vertebral bodies at T2-weighted images were detected. Bone scan revealed compression fracture on fourth lumbar vertebral body; and increased activity on left lateral part of the third lumbar vertebral body. These findings had suggested an adenocarcinoma metastasis to the vertebra, and radiotherapy had been performed. He had been followed up without any complaints until December 2002. At this time, weakness on both of his legs, and lumbar pain has recurred. Lumbar MRI was performed again. Lytic lesions had been detected at the sides of third, and fourth lumbar vertebral bodies and fluid collections had been detected in intervertebral discs (Figs. 1, 2, 3). He had been operated on, all necrotic material was surgically removed, and biopsy materials from disk, and bone tissue had been examined pathologically and microbiologically. Histological examination of the biopsy specimens with hematoxylin–eosin, and periodic acid-Schiff stain revealed mycotic spondylodiscitis. Gram staining of the biopsy specimens had disclosed fungal elements, and culture had grown yeast. After these findings the patient referred to our clinic.

Fig. 1
figure 1

Sagittal T1-weighted, fat saturated T2-weighted and axial T1-weighted images show pathological signal intensities at the sides of third and fourth lumbar vertebral end-plates. There is also pathological signal in disk space

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Fig. 2
figure 2

Sagittal T1-weighted, fat saturated T2-weighted and axial T1-weighted images show pathological signal intensities at the sides of third and fourth lumbar vertebral end-plates. There is also pathological signal in disk space

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Fig. 3
figure 3

Sagittal T1-weighted, fat saturated T2-weighted and axial T1-weighted images show pathological signal intensities at the sides of third and fourth lumbar vertebral end-plates. There is also pathological signal in disk space

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On admission to our clinic, he reported pain on the lumbar area, and general weakness. The leukocyte count was 6,500/mm3 with 65% neutrophils; the erythrocyte sedimentation rate was 35 mm/h; C-reactive protein was 5 mg/dl (N 0–5 mg/dl). Biochemistry was totally normal. Abdomen CT revealed metastatic lesion on the right lobe of the liver, also disclosed soft tissue mass with free air images near to left psoas muscle. Because of the patient’s poor general condition surgical drainage of this abscess could not be performed. The patient was treated with amphotericin B for 40 days. A control CT after therapy showed a significant regression of abscess. The therapy switched to oral itraconazole. After 2 months of itraconazole treatment, he has been doing well but he failed to come following up.

Microbiological studies

Identification of the case isolate was performed in Deep Mycoses Laboratory (Department of Microbiology and Clinical Microbiology, Basic Medical Sciences Section). Minimal inhibitory concentrations of antifungal agents for the isolate were found as follows: Amphotericin 0.25 μ/ml, fluconazole 32 μ/ml, itraconazole 4 μ/ml, ketoconazole 4 μ/ml, terbinafine 0.5 μ/ml.

Discussion

Blastochizomyces capitatus (formerly T. capitatum, G. capiatatum) is a normal inhabitant of soil, human skin, digestive and respiratory tract [8, 9]. As far as Trichosporon species are concerned T. capitatum (G. capitatum) has been considered as a separate genus and retained as B. capitatus [10–12]. Although it is a frequent cause of superficial mycotic infections such as white piedra, it rarely causes systemic infection in a non-compromised individual [9]. The incidence of invasive fungal infections with Trichosporon spp. in patients with hematological malignancies has risen over the last two decades, mainly as a result of the increased use of immunosuppressive therapy. There are also several studies suggesting this species as the most common yeast type after Candida spp. causing fungal infection in cancer patients but in these reports B. capitaus is the genus that is the least frequent causative agent [13, 14].

B. capitaus is a yeast-like fungus with a low pathogenic potential, which is occasionally isolated from clinical specimens, usually without clinical significance [11]. Neutropenia, cytotoxic agents or corticosteroids administration, use of antibiotics, presence of central venous catheter have been presumed to predispose for infection or colonization with this fungal agent [10, 15]. Opportunistic infections with B. capitatus can occur in various types of immunocompromised patients; those with hematological malignancies are by far the most common victims. Underlying condition in all of the reported cases of spondylodiscitis due to this fungal organism is hematologic malignancy [1, 3, 5–7] and all of these local infections are secondary to documented fungemia except for one [6]. In two cases, the infections occurred during a period of neutropenia after cytotoxic chemotherapy [1, 6]. The other two patients had fungemia during the neutropenic phase after undergoing an allogeneic bone marrow transplantation, which was apparently cured with antifungal therapy [3, 5]. One of these patients developed proven multiple spondylodiscitis due to B. capitatus infection 7 months after cure; this second episode was considered to be a reactivation of a latent infection during immunosuppression for treatment of graft-versus-host disease [5]. Blood count had no abnormality in the other patient when spondylodiscitis was detected [3]. The other osteoarticular infection caused by B. capitatus reported in the literature is mandibular osteomyelitis. This infection also developed in a patient who had acute myelogenous leukemia and low neutrophil count due to cytotoxic chemotherapy [4]. The case we present here had a solid tumor and his neutrophil count was always in normal value. There was no clinical sign of infection such as fever, and there was no abnormality in laboratory values suggesting any infectious process and we also did not detect fungemia so the findings on vertebral MRI was considered as metastatic process due to colon adenocarcinoma instead of an infectious spondylodiscitis. Although antifungal therapy has been delayed in our patient due to the late diagnosis the clinical course was not so aggressive like the other cases reported in the literature. This dormant course in our case is thought to be due to the absence of neutropenia in any period. This observation also confirms the slow progression of infectious spondylodiscitis even if a fungal agent is present in the etiology like D'Antonio et al. [1] reported in their review. The insidious progression of clinical course, the no specificity of laboratory data, and the inability to recognize the etiologic agent without open biopsy or closed needle aspiration may lead to diagnostic and therapeutic delay like in our case.

B. capitaus is a fungus that is present in the soil, normal human skin, and digestive and respiratory tracts. The lungs, gastrointestinal tract, intravenous catheter sites, oral mucosa are thought to be the likely portals of entry for this agent [16]. We suspect that in our patient the organism was introduced during intraabdominal surgery due to impairment of integrity of the intestinal wall, and caused spondylodiscitis by contagious way.

Most disseminated B. capitaus infections in immunosuppressed patients who were severely neutropenic had a fatal outcome [8, 10–12, 17–25]. Besides these cases therapeutic success with amphotericin B [4, 10, 13, 25], ketoconazole, itracaconazole [1], 5-fluorocytosine [26] has been reported. According to the results of in vitro antifungal susceptibility tests of our clinical isolate amphotericin B was convenient agent for therapy. This result correlated with clinical observation of intraabdominal inflammation regression. The therapeutic response of amphotericin B in our case was also due to the absence of severe immunosuppression.

In conclusion, we present another case of infectious spondylodiscitis due to B. capitaus, which is reported first in Turkey and tried to attract attendance to this emergent fungal pathogen as an etiologic agent in osteoarticular infections in cancer patients.