Molecular identification of Coccidioides spp. in soil samples from Brazil

Abstract

BackgroundSince 1991 several outbreaks of acute coccidioidomycosis (CM) were diagnosed in the semi-arid Northeast of Brazil, mainly related to disturbance of armadillo burrows caused by hunters while digging them for the capture of these animals. This activity causes dust contaminated with arthroconidia of Coccidioides posadasii, which, once inhaled, cause the mycosis. We report on the identification of C. posadasii in soil samples related to outbreaks of CM.ResultsTwenty four soil samples had their DNA extracted and subsequently submitted to a semi-nested PCR technique using specific primers. While only 6 (25%) soil samples were positive for C. posadasii by mice inoculation, all (100%) were positive by the molecular tool.ConclusionThis methodology represents a simple, sensitive and specific molecular technique to determine the environmental distribution of Coccidioides spp. in endemic areas, but cannot distinguish the species. Moreover, it may be useful to identify culture isolates. Key-words: 1. Coccidioidomycosis. 2. Coccidioides spp. 3. C. posadasii. 4. Semi-arid. 5. Semi-nested PCR

Recent Advances in Our Understanding of the Environmental, Epidemiological, Immunological, and Clinical Dimensions of Coccidioidomycosis

“…PCR using Coccidioides-specific ribosomal DNA (rDNA) primers in a nested reaction protocol has allowed detection in some cases (45,46), although the sensitivity of detection is not clear. This approach, while useful for identifying positive sites, does not allow for molecular or phenotypic analysis.…”

“…More recently, efforts to isolate Coccidioides from the soil for niche identification and population analyses have focused on sites of historical human exposure (44), recent exposure of humans or dogs (18), or associations with rodents (45) or armadillos (46). PCR using Coccidioides-specific ribosomal DNA (rDNA) primers in a nested reaction protocol has allowed detection in some cases (45,46), although the sensitivity of detection is not clear.…”

Diagnosis and Initial Management of Musculoskeletal Coccidioidomycosis in Children

“…In 1896, Rixford and Gilchrist reported the first two cases of coccidioidomycosis in the United States, naming the organism Coccidioides ("resembling Coccidia") immitis ("not mild") 21 . The spectrum of disease presentation was first appreciated in 1929, when Chope, then a second year medical student, accidentally inhaled a cloud of spores , where several small outbreaks have been associated with the digging of armadillo burrows and subsequent inhalation of aerosolized arthrospores 31 . Coccidioides spp.…”

Viability and molecular authentication of Coccidioides spp. isolates from the Instituto de Medicina Tropical de São Paulo culture collection, Brazil

“…Since 1978, the disease has been diagnosed in several patients in the semi-arid northeastern region of Brazil, more frequently in Piauí, Ceará, Maranhão, and Bahia states 10,14,23,31,33 . Studies using delayed hypersensitivity tests with coccidioidin have demonstrated the presence of healthy infected individuals in these states, which are now considered to be endemic areas in Brazil 6,7,33 .…”