Skip to main content

Normal Flora of Human Body, Skin, Respiratory Tract, Intestinal tract, Genitourinary tract, Eye

There are some species of bacteria and fungi that are a permanent resident of specific sites of our body. Bacteria and fungi are included in the normal flora, viruses and parasites are not a part of normal flora.
These bacteria and fungi which are normal and permanent residents of specific sites of our body, don’t usually cause the disease, but they may cause disease in certain situations. Usually, they protect us from diseases by competing with the disease-causing bacteria for space and food.

Normal Flora of Human Bodynormal flora of human body

Normal Flora of Skin

The following bacteria and fungi are part of normal and permanent inhabitants of the skin
  1. Staphylococcus epidermidis
  2. Staphylococcus aureus
  3. Corynebacterium diphtheria
  4. Group G streptococci
  5. Pseudomonas aeruginosa
  6. Peptococcus
  7. Candida albicans (fungi)

Normal flora of Respiratory Tract

  • Nose: Staphylococcus aureus, Staphylococcus epidermidis, Corynebacterium diphtheria, and other streptococci are the part of the normal flora of nose.
  • Throat, Larynx & Trachea: Viridans streptococci, Streptococcus pyogenes, Streptococcus pneumoniae, Neisseria species, Haemophilus influenzae, Staphylococcus epidermidis are permanent residents of the respiratory tract.

Normal Flora of the Oral Cavity

  • Mouth: Viridans streptococci and other species of streptococci.
  • Dental Plaque: Streptococcus mutans
  • Gingival Cervices: Bacteriodes, Fusobacterium, Streptococci, Actinomyces

Normal Flora of Intestinal Tract

  • Small intestine: Enterococci, Lactobacilli, Staphylococci, Candida albicans.
  • Colon: Bacteroides, especially bacteroides fragilis, Escherichia coli, Enterobacter, Serratia, Pseudomonas aeruginosa, Bifidobacterium, Fusobacterium, Lactobacillus, Enterococci especially E. faecalis, Non-enterococci, especially S bovis, Streptococcus anginosus, Clostridium especially perfringens.

Normal Flora of Genitourinary Tract

  • Vagina: Lactobacillus, Streptococcus agalactiae, Streptococcus anginosus, Various Gram-negative rods, B. fragilis, Corynebacterium and Candida albicans
  • Urethra: Staphylococcus epidermidis, Corynebacterium diphtheria, Various streptococci, Various Gram-negative rods and Mycoplasmas
  • External Genitalia: Mycobacterium smegmatis

Normal Flora of Eye

  1. Corynebacterium xerosis
  2. Staphylococcus aureus
  3. Staphylococcus epidermidis
You can clearly see that in the above list certain bacteria are known to cause serious diseases, such as E. coli, Staphylococcus aureus, S. pneumonia and many others, but remember that there are present in a balanced number. If the number of any of the above bacteria increases due to any cause, then these may cause disease. For example, Clostridium difficile is present in small numbers in the colon, but after long term antibiotic use that kills a large number of bacteria other than Clostridium difficile, cause a serious disease called pseudomembranous colitis due to over-growth of clostridium difficile. Therefore, if the bacteria are present in a balanced number then they all are friendly bacteria.


Popular posts from this blog

Human Parasites, Types of Parasites, and Classification

Parasite: A parasite is a living organism which gets nutrition and protection from another organism where it lives. Parasites enter into the human body through mouth, skin and genitalia. In this article, we will generally discuss the types and classification of parasites. It is important from an academic point of view. Those parasites are harmful, which derives their nutrition and other benefits from the host and host get nothing in return but suffers from some injury. Types of Parasites Ecto-parasite: An ectoparasite lives outside on the surface of the body of the host. Endo-parasite: An endo-parasite lives inside the body of the host, it lives in the blood, tissues, body cavities, digestive tract or other organs. Temporary parasite: A temporary parasite visits its host for a short period of time. Permanent parasite: Permanent parasite lives its whole life in the host. Facultative parasite: A facultative parasite can live both independently and dependently. It lives in the

How to taper off, wean off beta blocker, atenolol, Propranolol, Metoprolol

Beta blockers include, atenolol (Tenormin), propranolol (Inderal ) and metoprolol (Lopressor) and are used to treat high blood pressure, certain cardiac problems, migraine and few other conditions. People usually take atenolol, propranolol or metoprolol for many years as a treatment of high blood pressure or after having an episode of heart attack . Sometimes, it becomes necessary to withdraw these beta blockers due to their potential side effects that trouble the patients or sometimes doctor wants to change the drug and shift the patient to some other anti-hypertensive medicine. No matter whatever the cause is, whenever, a patient who has been using a beta blocker for a long period of time, and he needs to be stopped from further usage of that beta blocker, must not stop taking it. One should taper off the dose of a beta blocker. Now a question arises how to wean off or taper off a beta blocker? The method of tapering off beta blocker varies from individual to individual. Allow you