BACTERIAL COLONIZATION ON HUMAN SKIN
BACTERIAL COLONIZATION ON HUMAN SKIN
TABLE OF CONTENTS
TITLE PAGE I
TABLE OF CONTENTS V
1.0 INTRODUCTION 1
2.0 LITERATURE REVIEW 2 – 6
2.1 PURPOSE OF THE STUDY 6
3.0 MATERIALS AND METHODS 7
3.1 MATERIALS USED 7
3.2 STERILIZATION OF MATERIALS 7
3.3 COLLECTION OF SAMPLES 7
3.4 PREPARATION OF CULTURE MEDIA 7
3.5 INOCULATION OF MEDIA 8
3.6 SUB-CULTURING OF MICROBIAL GROWTH 8
3.7 MAINTENANCE OF PURE CULTURE 8
3.8 CHARACTERIZATION OF BACTERIAL ISOLATES 8
3.9.0 GRAM STAINING 8 – 9
3.9.1 CAPSULES STAINING AND SPORE STAINING 9
3.9.2 COAGULASE TEST 9
3.9.3 CATALASE TEST 9
3.9.4 OXIDASE TEST 10
3.9.5 SUGAR FERMENTATION 10
3.9.6 MOTILITY TEST 10
3.9.7 IDENTIFICATION OF BACTERIAL ISOLATES 10
4.0 RESULTS AND DISCUSSION 11 – 13
5.0 CONCLUSION AND RECOMMENDATION 14 – 15
The surface of human body were Scrubs with moistened swab stick, these was used to streaked the surface of prepared nutrient agar for bacterial growth and incubated at an appropriate temperature. The bacterial isolated were identified to be Staphylococcus aureus, Streptococcus pyogene and Klebsiella aurogene.
A diverse microbial flora is associated with the skin and mucous membrane of every human being from shortly after birth until death. The human body which contains about 1013 cells routinely harbors about 1014 bacteria. This bacterial population constitutes the normal microbial flora. The normal microbial flora is relatively stable with specific genera populating various body regions during particular periods in an individual’s life. Tannock (1995).
Microorganisms of the normal flora may aid the host [By competing for micro-environment more effectively than such pathogens Salmonella Spp or by producing nutrients that the host can use. It may harm the host by causing dental caries, abscesses or other infectious diseases or it may exist as commercials by inhabiting the host for long periods without causing detectable harm or benefits. Even though most elements of the normal microbial flora inhabiting the human skin, nails, eyes, genitalia and gastrointestinal tract are harmless in healthy individuals, these organisms frequently cause disease in compromised hosts.
The normal flora in human usually develops in an orderly sequence, after birth leading to the stable populations of bacteria that made up the normal adult flora. The main factor determining the composition of the normal flora in a body region is the nature of the local environment which is determined by pH, temperature, redox potential, oxygen, water and nutrient levels. Other factors such as peristalsis, saliva hysozyme secretion and secretion of immunoglobulin also play roles in flora control. The local environment is like a concern to in which one principal instrument usually dominates. For example, an infact begins to contact organisms as it moves through the birth canal. A gram positive population [Bifido bacteria] predominates in the gastrointestinal tract early in life. If the infant is breast-fed. This bacterial population is reduced and displaced some what by a gram negative flora [Entero bacteriaceae] when the baby is bottle feel. The type of liquid diet provided to the infant is the principal instrument of this flora controls, immunoglobulins and perhaps other element is breast milk may also be important.
2.0 LITERATURE REVIEW
The body surface habour many microorganism which could be bacteria and fungi. Bacterial survival and the extent of colonization probably depend partly on the exposure of skin to a particular environment and partly on the innate and species of a specific bactericidal activity in the skin. Conversely, Streptococci viridans are not seen in large numbers on the skin or in the nose but dominate the oral flora. They synthesize and excrete vitamin in excess of their own needs which can be absorbed as nutrients by their host. It prevent colonization by pathogens by competing for attachment sites or for essential nutrients. This is though to be their most important effect which has been demonstrated in the oral cavity, the intestine and the skin. They may antagonize other bacteria through the production of substances which inhibit or kill non-indigenous species. The intestinal bacteria produce a variety of substance ranging from relatively nonspecific fatty acids and peroxides to highly specific bacteriocins which inhabit other bacteria. It stimulate the development of certain issues that is the caecum and certain lymphatic tissues in the gastrointestinal tract. It also stimulate the production of natural antibodies. Since the normal flora behave as antigens in an animal, they induce an immunological response in particular antibody-mediated immune response. Bacteria normal flora colonizes various parts of the body which include the following: oral cavity, skin, conjunctiva, teeth, nucous membranes, upper respiratory tract, nasal membrane, pharynx [throat], Gastroin testinal tract, Stomach, small intestine, colon, urinogenital tract and virginal.
Few of these predominant bacteria at their various anatomical locations in adults are shown in the table below.
|Anatomical Location||Predominant Bacteria|
|Skin||Staphylococcis, epidermis and Corynebacteria|
|Conjunctiva||Gram-positive cocci and Gram-negative rods|
|Oral cavity||Streplococci, Staphylococci, Lactobacilli and corynebacteia|
|Mucous membranes||Streptococci and lactic acid bacteria|
|Nasal membranes||Staphylococcus aureus and corynebacteria|
|Pharynx [throat]||Streptococci, neisseria, Gram-negative rods and cocci.|
|Gastrointestinal tract||Streptococci, Lactobacilli Bacteroides|
|Small intestine||Lactics, enterics, enterococci and bifidobacteria.|
|Colon||Bacteroides, Lactics, enterics, enterococci, clostridia, methanogen.|
|Urogenital tract||Staphylococcus epidermides, Enterococcus faecalis|
|Vagina||Lactic acid bacteria during child bearing years.|
Characteristics of few Bacterial Skin Flora
The common predominant bacteria floras are Staphylococcus epidermis corynebacteria, Streptococci and Lactobacilli.
Staphylococcus epidermis is a major inhabitat of the skin and in some areas it makes up more than 90% of the resident aerobic flora. The skin microbes can also be found in the most superficial layers of the epidermis and in the upper parts of the hair follicles. They also produce fatty acids that inhibit the growth of fungi especially the yeast on the skin.
Corynebacteria and certain related propionic acid bacteria are consistent skin flora. Some have been implicated as a course of acne. Conynebacterium diphtheriae, the agent of diphtheria was considered a member of the normal flora before the widespread use of the diphtheria toxoid which is used to immunize against the disease.
Staphylococcus are rarely seen on normal skin. They are occasionally found on the normal flora of the conjunctiva. The paucity of β-hemolytic streptococci on the skin is attributed at least in part to the presence of lipids on the skin Hemolytic streptococci exist primarily in the mouth from where they are they can also spread to the skin.
Lactobacilli. In the oral cavity probably contribute to acid formation that leads to dental caries. Lactobacillus acidophilus colonize the vaginal epithelium during child bearing years and establishes the low pH that inhibits the growth of pathogens. Lactobacilli are though to adhere to the gastrointestinal epithelium using polysaccharide capsule to attach to specific receptions on the epithelia cells. The major body part in which invasion of bacteria occurs mostly are on skin and gastrointestinal tract.
The stomach is a relatively hostile environment for bacteria. In the upper gastrointestinal tract of adult humans, the esophagus contains only the bacteria swallowed wit Sp Saliva and food. Because of the high acidity of the gastric juice, very few bacteria [mainly acid-tolerant lactobacilli] can be cultured from the normal stomach. Some Helicobacter Species can colonize the stomach and are associated with type β gastritis and peptic ulcers disease. Aspirates of duodenal or jejunal fluid contain approximately 103 organisms/ml in most individuals. Most of the bacteria cultured [Streptococci, Lactobacilli and Bacteroides] are thought to be transiat.
Although the normal flora can inhibit pathogens many of its membrane can produce disease in humans. Anaerobes in the intestinal tract are the primary agents of intra-abdominal abscesses and peritonitis. Bowel perforations produced by appendicitis, Cancer, infarction, surgery or gun shot wounds almost always seed the peritoneal cavity and adjacent organs with the normal flora. It can cause problems within the gastrointestinal human. Treatment with antibiotics may allow certain anaerobic specifics to become predominant and cause disease. For example, Clostridium difficile which can remain viable in a patient undergoing antimicrobial theory may produce Pseudomenbranous colitis other intestinal pathological conditions or surgery can cause bacteria over growth in the upper layer of intestine. Anaerobic bacteria can then deconjugate bile acids in this region and bind available Vitamin B12 so that the vitamin and facts are malabsorbed.