Normal flora General aspects Remember definition organisms frequently found on or within body of healthy individuals Most are bacteria but some are viruses fungi, and protozoa We do not carry all of them all of the time Each person has individualized normal flora BIOL 533 Lecture two
BIOL 533 2 Lecture Two Normal Flora • General aspects – Remember definition: organisms frequently found on or within body of healthy individuals – Most are bacteria, but some are viruses, fungi, and protozoa • We do not carry all of them all of the time • Each person has individualized normal flora
Normal flora Some are found only on body others also found in environment Problem: some people have transient normal flora(pathogens) Example: about 10% of population have meningococcus or pneumococcus as normal flora BIOL 533 Lecture two
BIOL 533 3 Lecture Two Normal Flora • Some are found only on body; others also found in environment • Problem: some people have transient normal flora (pathogens) – Example: about 10% of population have meningococcus or pneumococcus as normal flora
Importance Opportunistic infections: normal flora in unusual sites; for example Bacteriodes from intestine into deeper tissues as a result of trauma(or surgery Staphylococci from skin and nose Streptococci and gram cocci from throat and mouth BIOL 533 Lecture two
BIOL 533 4 Lecture Two Importance • Opportunistic infections: normal flora in unusual sites; for example: – Bacteriodes from intestine into deeper tissues as a result of trauma (or surgery) – Staphylococci from skin and nose – Streptococci and Gram— cocci from throat and mouth
Importance Depends on pathogen and on defenses of host i Candida(yeast causes pneumonia in people undergoing cancer chemotherapy Pneumocystis carinii(common inhabitant of lung causes pneumonia and death in AIDS patients BIOL 533 Lecture two
BIOL 533 5 Lecture Two Importance • Depends on pathogen and on defenses of host: – Candida (yeast) causes pneumonia in people undergoing cancer chemotherapy – Pneumocystis carinii (common inhabitant of lung) causes pneumonia and death in AIDS patients
Immune stimulation Antigenic stimulation by normal flora do not have high antibody titers Serve as defense mechanism even in low concentration Bacterial stimulation leads to production of Iga that is secreted through mucus membranes Probably interfere with colonization of deeper tissues BIOL 533 Lecture two
BIOL 533 6 Lecture Two Immune Stimulation • Antigenic stimulation by normal flora— do not have high antibody titers – Serve as defense mechanism even in low concentration – Bacterial stimulation leads to production of IgA that is secreted through mucus membranes • Probably interfere with colonization of deeper tissues