HUMAN AND MICROBIAL INTERACTION Dr. Gemza Shah
NATURE OF INTERACTION BETWEEN MICROBES AND HUMAN • Transient microbiota may be present for days, weeks, or months • Resident microbiota permanently colonize the host.
HUMAN GIT SHOWING NORMAL FUNCTIONS OF NON PATHOGENIC MICROBES (NORMAL FLORA)
TYPES OF INTERACTION BETWEEN HUMANS AND MICROBES • Commensalism- Microbes that do not help or harm us are commensals. • Example: Most of the normal flora in the body. • Mutualism- Microbes and host benefit • Example: A microbe producing vitamins in the intestine • Parasitism-Microbe benefits and harms the host • Example: Pathogens • Opportunistic Pathogen-Normally harmless organism becomes pathogenic in a compromised host
COMMENSALISM • Commensalism is a class of relationship between two organisms where one organism benefits but the other is neutral (there is no harm or benefit).
COMMENSALISM • One of the best examples would be the relationship between cattle egret and cows and sheep (or cattle). The cattle egret is called so because it is often seen with cattle and livestock. Whenever horses, cows and other such livestock graze in fields, they tend to stir up and move many insects that have been resting on the grass. The cattle egret then catches them and preys upon them. The cattle egrets benefit from this because they manage to get the insects that they wish to prey on whereas the cattle remains unaffected.
MUTUALISM • Mutualism is a positive reciprocal relationship between two species. Through this relationship both species enhance their survival, growth or fitness. To a certain extent the relationship is more a reciprocal exploitation rather than a cooperative effort on the part of the individuals involved. • Its simply the living together of two organisms in a mutually beneficial relationship. .
PARASITISM • A form of symbiosis in which one organism (called parasite) benefits at the expense of another organism usually of different species (called host). The association may also lead to the injury of the host. • Ectoparasites live on the body surface of the host; endoparasites live in their hosts' organs, tissues, or cells and often rely on a third organism (the carrier, or vector) to transmit them to the host.
PARASITISM • The organism that benefits in a parasitic relationship is called the parasite. • The organism that is harmed in a parasitic relationship is called the host.
PARASITE-TAENIA SAGINATA • Taeniasaginata, also known as the beef tapeworm, is a parasite of both cattle and humans, causing taeniasis in humans. • Taeniasaginata occurs where cattle are raised by infected humans maintaining poor hygiene, human feces are improperly disposed of, meat inspection programs are poor, and where meat is eaten without proper cooking.
REASONS FOR WHICH PATHOGENS ENTER INTO HUMAN BODY Pathogenic bacteria enter through: • Cuts • Contaminated food or water • Close contact with an infected person • Contact with the faeces of an infected person • Breathing in the exhaled droplets when an infected person coughs or sneezes • Indirectly, by touching contaminated surfaces – such as taps, toilet handles, toys and nappies.
PREDISPOSING FACTORS OF THE HOST Make the body more susceptible to disease • Short urethra in females • Inherited traits such as the sickle-cell gene • Climate and weather • Fatigue • Age • Lifestyle • Chemotherapy
BENEFICIAL EFFECTS OF MICROBES Production of FoodsMicrobes are a key component in both home and industrial food preparation. Lactic acid bacteria are used to make yogurt, cheese, sour cream, buttermilk and other fermented milk products. Vinegars are produced by bacterial acetic acid fermentation. Yeast is used in the manufacture of beer and wine and for the leavening of breads. It is also involved in fermentations to convert corn and other vegetable carbohydrates.
BENEFICIAL EFFECTS OF MICROBES Medical, Pharmaceutical and Biotechnological ApplicationsCertain microbes can help us in the fight against other microbes. In human and veterinary medicine, that are used to treat and prevent infectious diseases, microbes are a source of antibiotics and vaccines. Microbes and Humans The microbes that normally live in association with humans on the various surfaces of the body (called the normal flora), such as Lactobacillus and Bifidobacterium, are known to protect their hosts from infections and otherwise promote nutrition and health
HARMFUL EFFECTS OF MICROBES • The harmful effects of microbes include diseases, destruction of crops, food items. • Micro-organisms, especially molds, can trigger respiratory infections and allergies if they grow in our workplaces or homes. • The parasitic worm infestations can result in iron deficiency anaemia • The round worms, hookworms and round worms result in growth retardation in children.
INFECTIOUS DISEASES OF HUMANS • Under certain circumstances, he invasion of the human body by microorganisms can produce harmful and potentially lethal results which are collectively known as the infectious diseases. • Infection means presence and multiplication of a living organism on or within the host, the terms COLONIZATION & INFECTION HAVE THE SAME MEANING.
INFECTIONS BY PATHOGENS • The normal flora of the human body can be disturbed in cases of nutritional deficiencies due to which the immune/defense systems of the body become weak. • As the immunity falls low the human body falls a prey to the pathogenic microbes • The intake of excessive antibiotics or strong chemotherapeutic drugs can also cause an imbalance between the pathogenic and non pathogenic microbes hence resulting in infections.
COMMON INFECTIOUS DISEASES OF HUMAN • The common infectious diseases are those caused by the pathogenic microbes: • Bacterial infectious diseases • Fungal Infectious Diseases • Parasitic Infectious Disease • Prion Infectious Diseases • Viral Infectious Diseases • The portal of entry can be: • Penetration • Direct contact • Ingestion • Inhalation
SOURCE OF INFECTIOUS AGENT • Endogenous • Exogenous: • Nosocmial infections. • Community acquired infections.
RELATIONSHIP OF THE CHAIN OF INFECTION WHILE PROVIDING NURSING CARE CHAIN OF INFECTION NURSING CARE The care provided by a skilled nurse is called nursing care. It has the utmost importance in limiting infectious diseases at this level. By using aseptic measures which include: 1. CLEANING CONTAMINATED OBJECTS2. WASHING HANDS3. CHANGING SOILED DRESSINGS4. WEARING GLOVES
CHAIN OF INFECTION • For an infection to develop, each link of the chain must be connected. Breaking any link of the chain can stop the transmission of infection.
NORMAL FLORA OF THE BODY • Within the womb, a baby’s body is axenic, meaning that the uterus is sterile and free of microbes, but soon after birth, the newborn becomes colonized by microbes, most of which are beneficial to human health. These microbes are called normal flora or normal microbiota.
EXISTENCE OF NORMAL FLORA Normal flora may: • Aid the host • Harm the host (sometimes) • Exist as commensals (no effect to the host)
BENEFITS OF NORMAL FLORA • Normal flora may aid the host in several ways: • Aid in digestion of food • Help the development of mucosa immunity • Protect the host from colonization with pathogenic microbes.
MICROBES RESIDING IN DIFFERENT BODY PARTS • The skin, especially the moist areas, such as the groin and between the toes. • The respiratory tract, particularly the nose. • Urinary tract. • The digestive tract, i.e. the mouth, the terminal ileum and the colon.
TYPES OF NORMAL FLORA • Many normal flora provide direct benefits, such as making vitamins or aiding digestion. Even if normal flora microbes merely take up space and resources, they help prevent pathogens (disease causing microbes) from easily invading the body and causing illness. Although there are many different species of normal flora, these bacteria, fungi and protozoan typically fall into one of two categories: • Resident Microbes • Transient Microbes
RESIDENT MICROTIA • The body’s resident microbiota are just that — residents. These species are life-long members of the body's normal microbial community, but are not found everywhere. There are many areas of the human body that remain axenic, and, in the absence of disease, are never colonized by normal flora. Axenic areas include the body cavity, lungs, central nervous system, circulatory system and upper urogenital regions. • Resident microbiota typically colonize the surface of the skin, mucous membranes, digestive tract, upper respiratory system and distal portion of the urogenital system. These microbes have a commensal relationship with their host, meaning that they do not cause harm while they benefit from feeding on the cellular waste and dead cells of the host's body.
TRANSIENT MICROBIOTA • Transient microbes are just passing through. Although they may attempt to colonize the same areas of the body as do resident microbiota, transients are unable to remain in the body for extended periods of time due to: • Competition from resident microbes • Elimination by the body’s immune system • Physical or chemical changes within the body that discourage the growth of transient microbes
OPPORTUNISTIC PATHOGENS • Under normal conditions, resident and transient microbes cause the host no harm. However, if the opportunity arises, some of these microbes are able to cause disease and become opportunistic pathogens. This can happen due to a number of different conditions: • When the immune system isn’t working properly, normal flora can overpopulate or move into areas of the body where they do not normally occur. • When the balance of normal microbes is disrupted, for example when a person takes broad spectrum antibiotics, microbes that are normally crowded out by resident microbes have an opportunity to take over. Tougher, antibiotic resistant bacteria, can get the upper hand. • Disease can result when normal flora are traumatically introduced to an area of the body that is axenic or that they do not normally occur in. Invasive medical procedures that introduce catheters or surgical wounds can allow microbes into areas of the body that are normally sterile.