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The normal microbial flora - Coggle Diagram
The normal microbial flora
<Definition of Normal Microbial Flora>
Microbes in mutual or commensal association with humans are called the normal flora. These organisms live in harmony with the host without causing damage in a healthy person.
<Opportunistic Pathogens>
The normal flora are considered opportunistic pathogens because they only cause disease under certain conditions, such as when host defenses are lowered or when the organism changes its natural habitat.
Division
1-Resident Flora:
This group consists of organisms regularly present in a given area at a given age. When disturbed, the resident flora soon re-establishes itself. Examples include( Escherichia coli in the intestine and Staphylococcus epidermidis on the skin)
Transient Flora:
These are pathogens and non-pathogens that inhabit the skin or mucous membranes for a limited period (seconds to weeks). They may cause disease if the normal resident flora is disturbed.it is intact is very little significance of disease
Beneficial Role: Resident flora play a protective role by preventing or suppressing pathogen colonization through bacterial interference. Intestinal flora also synthesize essential vitamins, like Vitamin K and B vitamins, and aid in nutrient digestion and absorption.
The normal flora various sites of the body
Skin and mucous membrane always carry a variety of organisms because they are in contact with the environment.
Normal flora and anatomic location
Enterococcus faecali
Bacteroides species
clostridium species
e-coli
Colon
Haemophilus species
Nasopharynx, conjunctiva
Corynebacterium species (diphtheroids)
Nasopharynx, skin, vagina
Lactobacillus species
Mouth, colon, vagina
Staphylococcus aureus
Nose
Staphylococcus epidermidis
Skin,nose, mouth, vagina
All internal organs (except GIT) and body fluids are normally sterile (free from any organisms).
Pathogenesis Concepts:
Colonization occurs when microbes live on or in a host without invading tissues or causing damage. Infection is the invasion and multiplication of microorganisms in close association with host tissues.
Type of micro organisms
Opportunistic microorganisms (potential pathogens):
cause disease under certain conditions:
1-low hosts defence mechanisms
2-change natural habits of micro organisms
3-alteration host tissue
Commensal or normal microbial flora
• Consist of micro-organisms present on body surfaces covered by epithelial cells and exposed to the external environment (gastrointestinal and respiratory tract, vagina, skin, etc.)
Pathogenic microorganisms (True Pathogens):
These organisms are capable of infecting the tissues of normal healthy subjects and have ways of overcoming the body's defenses.
Priorities
1-Infectivity: The pathogen must have a portal of entry to the host
2-virulence: The degree of pathogenicity of the organism.
3-Transmissibility: Organisms should have a portal of exit to shed off
Factor of virulence
1-adherence
2-invasiveness
2-antiphagacytic
3-toxin production
4-extra cellular enzymes