normal flora

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Related to normal flora: resident flora

nor·mal flor·a

(nōr'măl flōr'ă)
Microorganisms that normally reside at a given site and under normal circumstances do not cause disease.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012

normal flora

Microorganisms including bacteria, protozoa, and fungi that are found on or in specific areas of the body. The skin and mucous membranes of the oral cavity, intestines, upper respiratory tract, and vagina have specific, permanent flora. They are harmless, even beneficial, in their usual sites, and they inhibit the growth of pathogens, but they can cause infection if they are introduced into unusual sites. If the proportions of the various microorganisms are disrupted, one species may overgrow, as does Candida when bacterial flora are diminished by antibiotics. Synonym: resident flora See: colitis, pseudomembranous; infection; microorganism

The largest concentration of bacteria in humans is in the colon, where more than 400 genera may coexist. In the colon, anaerobic bacteria outnumber aerobic bacteria 1000:1, and there may be 1011 per g of fecal material. The anaerobic gram-positive lactobacilli may be concentrated in the vagina at the 105 to 108/ml level, but 20% of women have no detectable anaerobes in the vagina. In dental plaque and gingival sulci, the bacteria may reach a concentration of 1012/ml.

See also: flora
Medical Dictionary, © 2009 Farlex and Partners

Normal flora

The mixture of bacteria normally found at specific body sites.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Primary respiratory tract infection and infections or disruption of the gastrointestinal and genitourinary tract mucosa could lead to invasion and secondary infection with Gemella species as they are normal flora of these tracts.
However, the normal flora in apparently healthy camels can be altered by several factors such as bad sanitation, stress due to transportation, sudden change in feed, low herd health status, and immunosuppression.
Normal flora are "good" bacteria and are beneficial to the environment and all living species.
This could indicate that, in the cases where disease was present, the normal flora became opportunistic pathogens.
The results showed that the oropharyngeal flora remains same harbouring only the normal flora indicating that ENT infections in most of the cases are due to either viral or fungal aetiology.
The modes of acquiring fungal infection involves: (1)primary fungal infection via either inhalation of spores, traumatic implantation or overgrowth of normal flora, (2) fungal toxins, and (3) allergic response and affects the level of involvement of the infection3.
epidermidis, a normal flora of healthy human skin and mucosal microbial communities has emerged as a common cause of nosocomial infections, mostly occurring in immunocompromised hosts.
Normal flora was the maximum finding in two groups and Streptococcus pyogenes was the second highest in frequency in both sides.
We attribute the infection of this area to inoculation of the vocal fold with the normal flora of the aerodigestive tract.
The sensitivity was only 88% and it had a high rate of false positives, with normal flora difficult to distinguish from GBS.
The primary pathogen of superficial pyoderma cases involves Staphylococcus intermedius, a member of the normal flora in most dogs (Noble and Kent, 1992; Hill and Moriello, 1994; Ihrke, 1996; Scott et al., 1998).
israelii, a gram-positive, anaerobic bacilli, and is considered part of the normal flora of the gastrointestinal tract in humans.[sup.3,4] Overall, infection of the genitourinary system is rare, with only a few reported cases.[sup.2,5,6]