NORMAL HUMAN FLORA

                         NORMAL HUMAN FLORA

 HUMAN MICROBIOME

 The group of microorganisms that reside on the surface and in deep layers of skin, in the saliva and oral mucosa, in the conjunctiva, and in the gastrointestinal tracts including bacteria, fungi are called  microbiome (or human micro biota) .

               Some of these organisms perform tasks that are useful for the human host. However, the majority have no known beneficial or harmful effect. Those that are expected to be present, and that under normal circumstances do not cause disease, but instead participate in maintaining health, are deemed members of the normal flora.

NORMAL BACTERIAL FLORA

 A diverse microbial flora reside on human body Area like the skin and mucous membranes. They are present shortly after birth until death .

 Total Number of Normal flora:10^14 bacteria

Normal flora may: 

a. Aid the host 

b. Harm the host (in sometimes) 

c. Exist as commensals (no effect to the host) 

 (Viruses and parasites are NOT normal microbial flora • Most investigators consider that they are not commensals and do not aid the host)

Normal Flora and Pathogenesis

 1. Transient colonization 

2. Permanent colonization 

3. Disease

Colonization vs. Infection

 Colonization: establishment of a site of reproduction of microbes on a person without necessarily resulting in tissue invasion or damage.

 Infection: growth and multiplication of a microbe in or on the body of the host with or without the production of disease.

SIGNIFICANCE OF NORMAL FLORA 

1.  More bacterial than human cells in the body 
2. Provide some nutrients (vitamin K) 
3. Stimulate immune system, immunity can be cross-reactive against certain pathogens 
4. Prevent colonization by potential pathogens (antibiotic-associated colitis, Clostridium difficile)
5. Aid in digestion of food 
6. Help the development of mucosa immunity 
7. Protect the host from colonization with pathogenic microbes. 

 FACTORS INFLUENCING NORMAL FLORA

1. Local Environment (pH, temperature, redox potential, O2, H2O, and nutrient levels…). 

2. Diet

3. Age 

4. Health condition (immune activity…) 

5. Antibiotics,…..etc 

COMPOSITION OF THE NORMAL FLORA 

The normal flora of humans are exceedingly complex and consist of more than 200 species of bacteria. The makeup of the normal flora may be influenced by various factors, including genetics, age, sex, stress, nutrition and diet of the individual.

                                                                                Three developmental changes in humans, weaning, the eruption of the teeth, and the onset and cessation of ovarian functions, invariably affect the composition of the normal flora in the intestinal tract, the oral cavity, and the vagina, respectively. 

WHEN WE GET COLONIZED WITH NORMAL FLORA

A human first becomes colonized by a normal flora at the moment of birth and passage through the birth canal. In utero, the fetus is sterile, but when the mother's water breaks and the birth process begins, so does colonization of the body surfaces. Handling and feeding of the infant after birth leads to establishment of a stable normal flora on the skin, oral cavity and intestinal tract in about 48 hours.

                                           The composition of a child’s bacterial flora is dependent on the mother’s micro flora, since she is the primary source for the child’s bacteria at the outset.

Normal Flora absent in …

In a healthy human, the internal tissues such as: 

• blood 

• brain 

• muscle 

• cerbrospinal fluid (csf.) are normally free of microorganisms. 

FECAL BACTERIOTHERAPY

Fecal bacteriotherapy, which is now officially and scientifically known as fecal micro biota transplantation and is also referred to as fecal micro biota therapy, fecal transfusion, fecal transplant, stool transplant, fecal enema or human probiotic infusion (HPI), is a medical treatment for patients with pseudomembranous colitis (caused by Clostridium difficile), or ulcerative colitis that involves restoration of colon homeostasis by reintroducing normal bacterial flora from stool obtained from a healthy donor.

Fecal micro biota transplantation (FMT) is an effort to calm a troubled bowel by reintroducing the vast diversity of collaborative bowel inhabitants after the usual mix has been disturbed. More than 1,000 different strains of bacteria coexist peacefully in the typical healthy bowel. But when the delicate balance is altered, by antibiotics or other causes, a few strains can become dominant, leading to severe diarrhea, inflammation and tissue damage.

                                                                    Like an organ transplant, fecal microbiota transplantation begins with finding a donor, often a family member. The treatment team collects a fresh stool sample, at least 200 to 300 grams. The sample is mixed with salt water in a blender and filtered to remove particulate matter. It can be administered to the recipient through a colonoscopy, as an enema, or -- when the inflamed region is higher in the colon -- through a naso-gastric tube.