5 Flashcards
Normal flora
Normal or Indigenous (Resident) flora - are microorganisms (bacteria, fungi, protozoa, and viruses), mostly bacteria that are frequently found in a particular site in normal healthy individual.
2 types of normal flora
Resident
Transient
Characteristics of normal flora
Tissue specificity
Usually specific bacteria colonize specific tissues by one or another of these mechanisms.
Tissue tropism - bacterial preference for certain tissues
Specific adherence - adherence that involves complementary chemical interactions b/n the 2 surfaces.
Biofilm formation -
Biofilm
Biofilm is an assemblage of microbial cells that is irreversibly associated (not removed by gentle rinsing) with a surface and enclosed in a matrix of primarily polysaccharide material.
•Many biofilms are a mixture of microbes, although one member is responsible for maintaining the biofilm & may predominate.
Normal flora may aid the host in several ways:
Immunostimulant
Exclusionary effect (vacuum effect) & protection from external invaders.
–Protect the host from colonization with pathogenic mo by occupying ecological niches & production of substances which inhibit or kill non-indigenous spp.
Production of essential nutrients Vit K & B
Aid in digestion of food
Disadvantages of Normal flora
They can cause disease in the following:
They can cause disease when individuals become immunocompromised or debilitated
Act as pathogens in tissues outside their habitat. e.g. normal flora of intestine may cause UTI
Cause confusion in diagnosis due to their ubiquitous presence and their resemblance to some of the pathogens
Normal flora cause opportunistic infections– especially
in hosts rendered susceptible
Where are normal flora found
Skin
Eyes(conjunctiva) & Ears(outer ear and auditory tube)
Respiratory tract (only upper until trachea)
Oral Cavity (mouth)
Gastrointestinal tract(most anaerobes)
Urogenital tract(lower tracts from urethra)
S.mutant
Normal flora in mount but cause dental plaques or gingivitis
Or can cause endocarditis after surgery
In GIT most are found in lower parts of small intestine and large intestine why
Stomach acidic
Small intestine upper part bile kills them
Skin bacterias classification
Transient washed off because oil sweat and acidic and dry
Resident axilla groin between toes
Host parasite relationship is called
Symbiosis - life together
3 types of symbiosis
Mutualism
Commensalism
Parasitism
2 types of pathogens
Strict pathogens
Opportunistic pathogens
Bacterial virulence mechanisms
Adhesins - mostly glycoprotein projections - adhere
Invasins - enter cell
Evading defenses by capsule slime
