Occurrence of Paracoccidioides lutzii in the Amazon Region: Description of Two Cases

Abstract

Abstract. Paracoccidioidomycosis (PCM), the most important human systemic mycosis in Latin America, is known to be caused by at least four different phylogenetic lineages within the Paracoccidioides brasiliensis complex, including S1, PS2, PS3, and Pb01-like group. Herein, we describe two cases of PCM in patients native from the Amazon region. The disease was originally thought to have been caused by P. brasiliensis. Despite the severity of the cases, sera from the patients were negative in immunodiffusion tests using the standard exoantigen from P. brasiliensis B-339. However, a positive response was recorded with an autologous preparation of Paracoccidioides lutzii exoantigen. A phylogenetic approach based on the gp43 and ARF loci revealed high similarity between our clinical isolates and the Pb01-like group. The occurrence of PCM caused by P. lutzii in the Brazilian Amazon (Pará State) was thus proven. The incidence of PCM caused by P. lutzii may be underestimated in northern Brazil.

Fatal Fungemia due to Paracoccidioides lutzii

“…These sequences were previously deposited at GenBank (http://www.ncbi.nlm.nih.gov/genbank/) and described by Matute and others, 3 Teixeira and others, 4 and Marquesda-Silva and others. 7 The nucleotide sequences were aligned using the Simultaneous Alignment and Tree Estimation software (SATé 2.2.2).…”

“…6 However, in recent years, we observed a high number of false negative tests using the standard antigenic preparation derived from the fungus B-339 (ATCC 32069; PS3) in double immunodiffusion (DID) or enzyme-linked immunosorbent assay. 7,8 This incongruence suggests an antigenic variability in the genus Paracoccidioides and may be related to subjects infected with different phylogenetic species. Here, we describe an atypical case of PCM fungemia, associated with negative serology in a male farm worker and discuss the importance of the early diagnosis for the management of the disease.…”

“…On the other hand, PCM serology has evolved over the years 28 and been reported to be an essential tool for rapid diagnosis 29,30 and patient follow-up. 6,31 Unfortunately, from a seroepidemiological point of view, the diagnosis of PCM caused by divergent phylogenetic species is difficult based on antigenic preparations of the reference strain B-339 (PS3), 7,8 and none of the serological tests developed to date are able to clearly diagnosis PCM caused by the five cryptic species, which favors delayed diagnosis and false negative results. Our negative results for the double immunodiffusion test using the antigenic preparation of the B-339 strain are in agreement with previous studies, 7,8 which reinforces the idea of antigenic variability in the genus Paracoccidioides.…”

“…6,31 Unfortunately, from a seroepidemiological point of view, the diagnosis of PCM caused by divergent phylogenetic species is difficult based on antigenic preparations of the reference strain B-339 (PS3), 7,8 and none of the serological tests developed to date are able to clearly diagnosis PCM caused by the five cryptic species, which favors delayed diagnosis and false negative results. Our negative results for the double immunodiffusion test using the antigenic preparation of the B-339 strain are in agreement with previous studies, 7,8 which reinforces the idea of antigenic variability in the genus Paracoccidioides. The negative serology should not be interpreted only as the absence of antibodies caused by immunosuppression 32 or drug therapy 31 ; thus, we emphasize the need for specific antigenic preparation from autochthonous strains, in addition to the use of the standard preparation of B-339, to improve the sensitivity and specificity of the serological test.…”

“…Currently, phylogenetic species 3 (PS3) is restricted to clinical cases in Colombia, 3,26 and just a few isolates from phylogenetic species 2 (PS2) have been reported in the literature 3,26 from Brazil and Venezuela. The geographical epicenter of P. lutzii is the central-west region of Brazil, 4 with scattered cases reported outside of this area 7,26 and a single strain reported outside Brazil. 4 Acquisition of the disease occurs through inhalation of conidia of Paracoccidioides spp.…”