Direct invasion of bones by highly pathogenic fungi in an in vitro model and its ecological significance.
Animal bones after being devitalized at death are strongly resistant to wear and tear and remain in the soil or environment much longer than other organic components from dead animals. Yet over the course of time they seem to disappear and thus our ecological surroundings are not cluttered with bone remnants. Mechanical factors creating compression or friction and chemical factors like pH of the soil and surroundings must together have provided concerted degrading effects. Microorganisms in the soil also help in this process by utilizing the organic components of devitalized bones. Certain highly pathogenic fungi that have been collected from soil from time to time and many other environmental fungi may take part in the degrading of the bone remnants. In this study, several strains from the highly pathogenic dimorphic fungi Coccidioides immitis, Blastomyces dermatitidis, Histoplasma spp., Paracoccidioides brasiliensis and also some strains of dematiaceous fungi (Exophiala spp. and Foncecaea pedrosoi) were inoculated to dissected and devitalized murine long bones that had been placed on solidified water agar plates to see if they would survive, grow and invade the bones. After being kept for 12 weeks at 25 degrees C all the parts of the histological sections of these bones showed invasion by most of the strains used in this study, although the cortical component of the bony architecture seemed to be comparatively resistant to invasion. Their ability to grow and sporulate in the aforementioned nutrient-limiting condition hinted at a possible role of these fungi in the degradation of devitalized bones.
Sharmin
Shahana
S
Research Center for Pathogenic Fungi and Microbial Toxicoses, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8673, Japan.
Kishi
Fukuko
F
Sano
Ayako
A
Kamei
Katsuhiko
K
Nishimura
Kazuko
K
Miyaji
Makoto
M
D000818:Animals; D001673:Biodegradation, Environmental; D001842:Bone and Bones / Q000033:anatomy & histology / Q000378:metabolism* / Q000382:microbiology*; D003470:Culture Media; D017753:Ecosystem; D005658:Fungi / Q000254:growth & development / Q000502:physiology*; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D008962:Models, Theoretical
D003470:Culture Media