The importance of serological assays in diagnosing acute pulmonary histoplasmosis

Abstract

Histoplasmosis is a systemic mycosis caused by inhalation of Histoplasma capsulatum microconidia. The disease does not normally affect immunocompetent individuals after a single, transient inhalation exposure. However, longer exposure may cause chronic or disseminated acute pulmonary infection. Herein, we report the case of a 24-year-old immunocompetent patient, who presented fever, cough and dyspnea for one month. The chest radiography revealed interstitial infiltrate and diffuse micronodules. The patient reported having had close and prolonged contact with bats. Diagnosis was confirmed by positive double immunodifusion and immunoblotting assays. She was treated with ketoconazole (400 mg) and there was complete resolution of the disease.

The use of nested Polymerase Chain Reaction (nested PCR) for the early diagnosis of Histoplasma capsulatum infection in serum and whole blood of HIV-positive patients*

“…These were subsequently grouped according to the clinical aspects of patients: Group I (GI): 12 patients co-infected with H. capsulatum / AIDS, Group II (GII): 8 patients with HP associated with other immunodeficiencies; Group III (GIII): 10 strains isolated from fungal lesions of patients; Group IV (GIV): 10 patients with AIDS and other infections; Group V (GV): 10 individuals not infected with HIV and with suspected pneumonia caused by bacteria; Group VI (positive control) consisted of 9 isolates of H. capsulatum from patients with/without AIDS. The analysis of samples from each group was performed by conventional methods (mycological, serological, molecular) using: (i) control strains (to establish the sensitivity of both the conventional laboratory techniques and molecular methods); (ii) mycological examination, direct microscopic examination stained by Giemsa'method; cultures in different media such as Sabouraud-Dextrose agar; Infusion heart-brain (DIFCO, Detroit, MI, USA); Agar tryptone soy agar (Oxoid, London, England) incubated at 30 º C and 35 º C, and growth of the pathogens for 60 days, and (iii) serological methods: double immunodiffusion (ID) and immunoblotting (IB) according to the modified method used by Davis et al 5 Molecular analysis was performed by nested PCR with specific sequences ("primers") for H. capsulatum: 18S rDNA region (HC18), 100 kDa (HC100) sequences, using a modified method of Bialek et al and 5.8 S rDNA-ITS (HC5.8) sequence by the modified method of Fugita et al 6,7 …”

Comparison of diagnostic methods to detect Histoplasma capsulatum in serum and blood samples from AIDS patients

“…Double immunodiffusion and immunoblotting were performed according to Freitas et al [ 17 ] and Passos et al [ 18 ], respectively, with some modifications.…”

Importance of the association of molecular and immunological diagnosis in immunocompetent patient with Histoplasma capsulatum and Cryptoccocus neoformans infection: a case report

“…The manifestations of mycoses were influenced by genetic and environmental conditions such as the amount of the fungal propagules in the soil, the immune status of the host and the virulence of the infecting strain [ 8 ]. Epidemiology of fungal infections is important in immunocompetent individuals, especially when the available diagnostic tools do not show conclusive results [ 9 , 10 ].…”

“…Definitive diagnosis is still based on the isolation and identification of the etiological agent, by growth of the fungi from sputum, blood, tissue biopsy or biological specimens [ 8 , 9 , 11 ]. If neither cultural nor morphological proof of infection is available, other approaches must be used [ 8 , 9 , 11 ].…”

“…Definitive diagnosis is still based on the isolation and identification of the etiological agent, by growth of the fungi from sputum, blood, tissue biopsy or biological specimens [ 8 , 9 , 11 ]. If neither cultural nor morphological proof of infection is available, other approaches must be used [ 8 , 9 , 11 ]. In contrast to other endemic mycoses, serologic assays for detection of specific host antibody responses and/or antigen detection often provide this additional information for the diagnosis of histoplasmosis and cryptococcosis [ 4 , 6 , 9 , 12 ].…”