Bacteria which make the normal flora

There is some amount of bacteria and fungi can be found in normal healthy individuals as well. Normal flora is the term used to describe these organisms. They are permanent

Residents of the human body. Common sites are skin, oropharynx, colon and vagina. Viruses and fungi can also be found in healthy individuals but they are not considered as normal flora. The number and the type of bacteria are varying according to the site of the body. Usually internal organs are free of any organisms.

Members of the normal flora	Anatomic location
Bacteroides species	Colon, throat, vagina
Candida albicans	Mouth, colon, vagina
Clostridium species	colon
Corynebacterium species	Nasopharynx, skin, vagina
Enterococcus faecalis	colon
E. coli and other coliforms	Colon, vagina, outer urethra
Gardnerella vaginalis	Vagina
Haemophilus species	Nasopharynx, conjunctiva
Lactobacillus species	Mouth, colon, vagina
Neisseria species	Mouth, nasopharynx
Propionibacterium acnes	skin
Pseudomonas aeruginosa	Colon, skin
Staphylococcus aureus	Nose, skin
Staphylococcus epidermidis	Skin, nose, mouth, vagina, urethra
Viridans streptococci	Mouth, nasopharynx

Normal flora of the skin

Skin is the site where most of the normal flora bacteria are found. Staphylococcus epidermidis is the predominant organisms. It is a non-pathogenic bacteria but it can be dangerous if it reaches prosthesis such as artificial heart valve. Other common bacteria are Propionibacterium and Candida albicans.

Normal flora of the respiratory tract

Nose, mouth and throat are the site where bacteria are found. Usually lower bronchi and alveoli are free of organisms. Streptococci species are the predominant organisms found in the respiratory tract. Neisseria species, eikenella and bacteroides are also found in the respiratory tract.

Normal flora of the intestinal tract

In normal fasting people, the stomach contains few organisms because of its low pH and its enzymes. The small intestine usually contains small numbers of streptococci, lactobacilli and yeasts. The colon is the major location of bacteria in the body.

Major bacteria found in the colon

Bacterium	Number/g faeces	Important pathogens
Bacteroides (B.fragilis)	1010-1011	Yes
Bifidobacterium	1010	No
Eubacterium	1010	No
Coliforms	107-108	Yes
Enterococcus	107-108	Yes
Lactobacillus	107	No
Clostridium	106	Yes

Normal flora of the vagina and urethra

The vaginal flora of adult women consists primarily of lactobacillus species. Since the vagina is located close to the anus members of faecal flora can also be found. Usually urine of a healthy individual is sterile. But organisms can be found in urethra.