Normal Microbial Flora Of The Human Body
12 Temmuz 2007
Normal microbial flora of the human body
Human beings, like other animals, harbor a wide array of microorganisms either on or in their bodies. The normal microbial flora is more of less constant for each species and is broadly divided into residents and transients. The former constitute a constant population, which cannot be completely removed permanently, while the later vary from time to time. Knowledge of the normal flora of the body is essential to an understanding of the interactions of the human beings and their pathogen-laden environment. The normal microbial flora plays an important role in body economy. They can
become pathogenic when host defenses impair,
prevent or interfere with colonization/invasion of pathogens
produce antibiotic substance e. g. colicin, which has harmful effect on pathogens
raise the overall immune status of the body against pathogens having related or shared antigens, and
the microflora of the intestinal tract synthesize vitamin K and several B vitamins (Vitamin B12, thiamin and riboflavin) which supply on occasion the bodys needs
cause confusion in diagnosis due to their ubiquitous presence and their resemblance to some of the pathogens.
Sites of human body where normal flora are found
Skin
Conjunctiva
Nose and nasopharynx
Mouth, gum pocket between the teeth, tonsil, pharynx
Intestine (At least 500 to 600 different species live in the large intestine)
Genitourinary tract (urethra, vagina)
Normal flora of the oropharynx
The mouth offers a hospitable environment for over 400 different microbial species. The mouth of the infant is not sterile at birth. It generally contains the same types of organisms in about the same relative numbers as those presenting mothers vagina. These organisms diminish in number using the first 2-5 days after birth and are replaced by the types of bacteria present in the mouth of the mother and nurse. Within 12 hours after birth a-hemolytic streptococci are found and become the dominant organisms of the oropharynx and remain s for life. Normal human pharynx contains different types gram-negative and gram-positive, cocci and bacilli. The normal pharynx also contains bacteria, which have the potential o cause respiratory infections, such as, Haemophilus influenzae, Staphylococcus aureus, Streptococcus pneumoniae, Streptococcus pyogenes and Moraxella catarrhalis.
Kategori: Biyoloji