Fatal Hematogenous Cryptococcosis in Apparently Immunocompetent Patient: Case Report

Abstract

Cryptococcosis is an opportunistic fungal infection caused by encapsulated and cosmopolitan yeasts, of which the causative agents of the disease are recognized as the complex of Cryptococcus neoformans species. This mycosis can have subacute or chronic clinical profile, and can be fatal, especially in immunocompromised individuals such as patients with HIV/AIDS, neutropenic individuals and transplant recipients. Here we report a fatal case of hematogenous cryptococcosis in a non-immunosuppressed individual. The patient, a 53-year-old adult male, was hospitalized in the ICU of a hospital in Recife, Pernambuco, Brazil. The patient died 48 hours after admission to the ICU. The etiological agent was identified by an automated testing system (BD PhoenixTM) and molecular taxonomy. The cause of the infection was diagnosed as Cryptococcus neoformans. Hematogenous cryptococcosis or cryptococcemia is a systemic mycosis that mainly affects immunocompromised individuals, and is identified by a blood culture positive for yeasts of the genus Cryptococcus. It is a rare disease compared to the other forms of clinical presentation, especially when the patient does not have a clinical condition compatible with immunosuppression.

Keywords: Cryptococcus Neoformans; Meningitis; Hematogenous Cryptococcosis; Immunocompromised

Introduction

Cryptococcosis is an opportunistic fungal infection caused by encapsulated and cosmopolitan yeasts of which the causative agents of the disease are recognized as the complex of Cryptococcus neoformans species, grouping the commonly known varieties C. neoformans var grubii and C. neoformans var neoformans and serotypes (A, D and AD), and the complex of species C. gattii, with serotypes B and C [1,2]. In Latin America, the study of this mycosis has been frequent, due to the high morbidity and mortality rates with more than 5,000 individuals affected with cryptococcal meningitis each year and 2,400 attributable annual deaths in Latin America alone [2].

This mycosis can have a subacute or chronic clinical profile, and is potentially fatal [3]. It can affect both apparently immunocompetent individuals and those who suffer from grave conditions, such as patients with HIV/AIDS, neutropenic individuals, transplant recipients, people with hematological malignancies and those undergoing prolonged therapy with corticosteroids [4-7]

Cryptococcosis often occurs due to the inhalation of viable fungal propagules, found in various substrates, such as decomposing organic matter, contaminated soil, and bird droppings, especially of pigeons. After inhalation, Cryptococcus presents the lungs as the primary focus of infection, where it can be phagocytosed by alveolar macrophages [8,6,9]. This disease is commonly reported afflicting the central nervous system, but also the kidneys, bones and skin [10,9].

While cryptococcosis of the central nervous system is the most frequent clinical form, hematogenic cryptococcosis in immunocompetent patients is rare, since it is considered an uncommon form of clinical presentation of the disease, and clinical manifestations are non-specific [4].

Due to a higher prevalence of bacterial infections and empirically prescribed treatments, such factors often contribute to the delay in the diagnosis of fungal infections, favoring a worse prognosis of the disease [11]. We report here a case of hematogenic cryptococcosis in a patient apparently immunocompetent, as a clinical-epidemiological alert in relation to this disease. We report here a case of hematogenic cryptococcosis in a patient apparently immunocompetent, as a clinical-epidemiological alert regarding the etiological agent of this disease.

Case Presentation

The patient was a 53-year-old unemployed man with dark skin. He had a history over the preceding three months of generalized myalgia, anorexia, steady weight loss (+/-20kg) and severe depression. Two weeks before being hospitalized, his clinical condition had become worse, with fever, dry cough, episodes of disorientation and psychomotor agitation. There was a recent diagnosis of systemic arterial hypertension. He stated he was a nonsmoker. At the start of hospitalization, hematuria was noted, with urine test results suggestive of infection. In response, intravenous empirical antibiotic therapy was started with ciprofloxacin, to treat sepsis with urinary focus. The patient continued with to constant fever and central nervous system alterations. On the fourth day after admission, he was transferred to the intensive care unit due to deteriorating clinical profile, with important dyspnea and hypoxemia, requiring mechanical breathing assistance due to severe acute respiratory insufficiency. New samples were collected (blood, urine and tracheal secretion) and the antimicrobial treatment regimen was modified, with administration of ceftriaxone and clindamycin, for respiratory tract infection due to probable bronchoaspiration. The results of the laboratory tests conducted at the moment of admission indicated leukocytosis (leukocytes = 13,700 cells/mm³ with 88.2% neutrophils/ reference value = 4.000-11.000/55-60 %), hemoglobin = 16g/dl (reference value = 14-18 g/dl); hematocrit = 47.5% (reference value = 42-52 %), urea = 98mg/dL (reference value = 19-49 mg/dL), creatinine = 0.9mg/dL (reference value = 0,7-1.3 mg/dL), aspartate aminotransferase = 51U/L (reference value = 15-46 U/L), alanine aminotransferase = 57 U/L (reference value = 9-72 U/L), lactate dehydrogenase = 619 U/L (reference value = 313-613 U/L), creatine phosphokinase = 195U/L (reference value = 30-190 U/L) and albumin = 2.6g/dL (reference value = 3,5-4,7 g/dL). The HIV and urine tests were negative. Computerized tomography of the thorax was carried out, revealing evidence of thrombus in the arterial segment of the lower right lobe, suggestive of pulmonary thromboembolism; and parenchymatous opacities in the lower lobes, some of them centroacinar with branched pattern, especially in the upper segment of the lower right lobe. Tomography of the abdomen revealed slightly heterogeneous texture of the liver, without signs of chronic hepatic disease. No other significant alterations were observed. Because of the deteriorating clinical profile and imaging results, bacilloscopy for BK of the tracheal secretion was requested and full intravenous anticoagulation therapy was initiated with enoxaparin. Forty-eight hours after transfer to the ICU, the patient died, before received the microbiological results of the blood, urine and tracheal secretion cultures. The blood from the catheter was collected aseptically (following biosecurity standards) in Vacutainer^® tubes with EDTA by venous puncture and was immediately transferred to flasks containing Brain Heart Infusion (BHI) medium. The flasks were then placed in a Bact/ALERT^® incubator and the presence Cryptococcus neoformans was identified with a BD Phoenix^TM automated system. Blood samples were also sent to the Medical Mycology Laboratory of Pernambuco Federal University (UFPE), where sheets contrasted with India ink were examined and the presence was observed of encapsulated yeasts (Figure 1). Subsequently, blood samples were seeded in Duplicate on Sabouraud Dextrose Agar (Difco) plus 50mg/L of chloramphenicol in Petri dishes, which were kept at temperatures of 30°C and 37°C for up to 15 days for isolation of the etiological agent. Finally, confirmation was performed by molecular taxonomy, where DNA from the yeast was extracted and submitted to sequencing of the D1-D2 domain of rDNA [12]. The primers used were NL1 (5’ - GCATATCAATAAGCGGAGGAAAAG-3’) and NL4 (5’ - GGTCCGTGTTTCAAGACGG - 3’). The PCR cycling consisted of initial denaturing at 95°C for 5min, followed by 35 denaturing cycles at 95°C for 30s each, annealing at 57°C for 30s, extension at 72°C for 30s and final extension at 72°C for 10min. At the end of the process, the samples were purified with the GeneJET PCR purification kit (Fermentas, UK) and sequenced by the sequencing platform of the Central Laboratory of the Center for Biological Sciences of UFPE. The isolate in question was identified as Cryptococcus neoformans, a sample of which is now stored in the culture collection of UFPE under URM7730.

    

    

    Figure 1: Direct microscopic images of blood cultures stained with India
ink, revealing budding and encapsulated yeast cells (arrows). Magnification:
400x.