AbstractsBiology & Animal Science

The occurrence of pathogenic fungi in the normal human body

by Helen Gertrude Resca

Institution: Boston University
Year: 1948
Record ID: 1521240
Full text PDF: http://hdl.handle.net/2144/6263


Each region of the body has its own natural micro-organisms, which constitute the normal flora of that region. Among the organisms present are bacteria and higher fungi. Pathogenic fungi in the normal flora regarded as important because of the threat which they offer to the health of the body. Under the proper circumstances, these pathogens can invade the tissues, setting up an infection. Fungus diseases which terminate fatally are numerically important, although they are responsible for only 0.03% of deaths in the United States in any year. Non-fatal fungus diseases are very prevalent, being almost as common as any bacterial diseases. Notable among these is coccidioidomycosis, acquired by 75 to 97% of the children on Indian reservations in Arizona. Tinea capitis is now referred to as an epidemic communicable disease. Dermatophytosis of the feet is also an ever-present mycosis which does not result in death. Fungus infections are, for the most part, endogenous origin. For instance, actinomycosis is not transmitted from one human to another, nor from animal to man. The causative organism, Actinomyces bovis, does not exist outside the body, so the infection must be endogenous. In the Ebers Papyrus, written about 1500 B.C., the first reference to fungi is found. But it was not until 1683 A.D., when Leeuwenhoek developed his lenses, that microorganisms were seen for the first time. Suspicion that microbes caused disease was harbored by Fracastor in 1543. The hair and scalp, although popularly believed to be free from living organisms; harbors many fungi among which is the pathogenic Pityrosporon ovale. Skin, even though is has been scrubbed clean, is never entirely free from bacteria. Monilia albicans, the etiologic agent of moniliasis, is found on normal skin. Cryptococci and mycodermata, responsible for cryptococcosis and geotrichosis, respectively, have been isolated from the skin and nails of individuals. Ordinary cleansing of the skin, which insures the proper action of the germicidal power, is sufficient to keep the pathogens found normally on the skin in check. However, a mere break in the skin, or excessive moistening of this protective barrier is in many instances, sufficient for pathogens to enter, and gain a foothold, to cause an infection. The feet provide a favorable environment for fungus growth, as in indicated by the high incidence of dermatophytoses of the feet. Men seem to be more susceptible to mycosis of the feet, according to figures presented. However, this has been shown to be due to the gymnasium habits and the mobilization of men, and not a sex difference. Some people must be more susceptible than others, though, since familial and conjugal transmission of ringworm of the groin is so rare that mycologists are convinced of the endogenous origin of this mycosis. The ears do not contain the agents of otomycosis, but these organisms, belonging mainly in the genus Aspergillus, are found on normal skin. Injury to the external auditory canal by the unskilled removal of excess cerumen has resulted…