Normal Flora of Human Body

• Normal flora refers to the population of microorganism that inhibit skin and mucous membrane of normal human body.

• Also known as microbiota refers to the diverse community of microorganism that inhibit various part of the human body.

• Microorganism include bacteria, virus, fungi and protozoa.

• They play crucial role in maintaining health and preventing disease.

• A healthy foetus in utero is free from microorganism.

  Classification

• Normal flora can be divide into two groups.

Resident flora

• It consist of organism which are regularly present in a particular area and when distrubed it re-establish itself.

• Example: E.coli

  Role of resident flora:

• Beneficial role:

  1. They prevent or suppress the colonization invasion of the body by pathogens.

  2. The bacterial flora of intestinal tract synthesis vitamins.

  3. Colicins produced by some organism of normal flora have a harmful effect on pathogen.

  4. The endotoxin liberated by them may help the defence mechanism of the body by triggering the alternative complement pathway.

• Disease production:

  1. They become pathogenic when the lost resistance is lowered.

  2. They may act as pathogen in tissue outside their normal habitat.

  3. Streptococcus mutans may cause dental caries.

  4. Use of broad spectrum antibiotics affect the normal flora.

  5. some time it may cause confusion in diagnosis due to their ubiquitous presence in the body.

Transient flora

• It consist of both non-pathogenic and potentially pathogenic bacteria that inhibit the body surface or mucous membrane for a limited period.

NORMAL FLORA OF THE SKIN

• Staphylococcus epidermis

• Staphylococcus aureus

• Corynebacterium xerosis

• Micrococcus

• E. coli

• Proteus

• Candida albicans

NORMAL FLORA OF CONJUNCTIVA

• Corynebacterium xerosis

• Staphylococcus epidermidis

• Moraxella

• Non-haemolytic stretococci

NORMAL FLORA OF NASOPHARYNX

• Diptheroids

• Staphylococci

• Streptococci

• Haemophilus species

• Pseudomonas aeruinosa, E. coli, Proteus also found in normal person.

NORMAL FLORA OF MOUTH

• Lactobacillus

• Vibrios

• Corynebacterium species

• Actinomycetes

• Mycoplasma

• Micrococci

NORMAL FLORA OF UPPER RESPIRATORY TRACT

• Sreptococcus pneumoniae

• Streptococcus pyogenes

• Streptococcus viridians

• Neisseria meningitis

• Neisseria subflav

• Moraxella

• Candida species

NORMAL FLORA OF GASTROINTESTINAL TRACT

• Leptotrichia

• Enterococci

• Colon bacilli

• Staphylococci

• Helicobacter pylori

• Lactobacillus species

• Streptococcus thermophilus

• Clostridium butyricum

• Enterobacter species

NORMAL FLORA OF GENITOURINARY TRACT

• Mycobacterium smegmatis

• Propionibacterium acnes

• Corynebacterium species