MICR J210 1st Edition Lecture 6 Outline of Last Lecture I. Antibiotic Action and Geneticsa. Historyb. Side effectsII. Normal FloraIII. Drug Resistance IV. Mechanisms of Gene Transfer in BacteriaV. Recombinant DNA TechnologyOutline of Current Lecture I. Symbiotic RelationshipsII. Normal MicrobiotaIII. Contamination and InfectionIV. How Pathogens Cause DiseaseV. Stages of Infectious DiseaseVI. Reservoirs of InfectionVII. EpidemiologyCurrent LectureSymbiotic Relationships- Symbiosis means to live together- Three types of symbiotic relationshipso Mutualism: the host and the bacteria benefit (E. coli in the colon)o Commensalism: the host is neither harmed or benefits but the bacteria benefits (Staph on the skin)o Parasitism: the host is harmed and bacteria is benefits (Tuberculosis in the lungs)Normal Microbiota- Organisms that colonize the body’s surfaces without normally causing disease- Two types of microbiotao Resident microbiotaThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. We have them most of our life Generally there all of the itme Generally there all of the time Most are commensal  Locations- Mucosa and GI tract- Oral cavity- Nose- Intestine- Male and female urinary and reproductive tractso Transient microbiota Remain on the body surface for only hours to months before disappearing Less transient microbiota than residential- Cannot persist ion the bodyo Competition from other microorganisms for food and nutrientso Elimination by the body’s defense cellso Chemical or physical changes in the body- Quick note: lysozyme is produced in tears and can digest PG and kill gram+ bacteria- Acquisition of Normal Microbiotao Development in the womb is sterile---free from all microorganismso Most resident microbiota is established during the first months of life outside of the wombOpportunistic Pathogens- Normal microbiota or other normally harmless microbes that can cause disease under certain circumstances- Conditions that provide opportunities for pathogenso Immune suppressiono Changes in the normal microbiotao Introduction of normal microbiota into unusual site on the bodyContamination and Infection- Contamination: the mere presence of microbes in or on the body- Infection: results when the organism has evaded the body’s external defenses, multiplied, and become established in the body- Routes of Entryo Site through which pathogens enter the bodyoo Four major types Skin Mucous membranes Placenta Parenteral route (i.e. trauma)- Some pathogens can cross the placentao Toxoplasmosis is associate with house cats so pregnant mothers should not clean the liter boxo Syphilis is a spirochete that can bore itself into the placenta to reach the baby- Infection v Diseaseo Infection: the invasion of the host by a pathogeno Disease: results only if the invading pathogen alters the normal function of the body (also known as morbidity) Manifestations of Disease- Symptoms: subjective characteristics only felt by the patient (headache, backache)- Signs: objective manifestations seen by the healthcare professional (fever, rash, etc.)- Syndrome: group of symptoms and sign that characterize a disease; points back to one disease- Asymptomatic: infections that lack symptoms but may still have the signs  Etiology: the study of the cause of disease Germ theory of disease: caused by infections of pathogenic microorganisms- Infectious diseases are caused by an infection organismHow Pathogens Cause Diseaseo Portals of Entryo Mucous membraneso Skino Parenteral routeo Number of invading microbeso How many got in?o Inoculationo Adherenceo Will they be able to stay in the host?o Penetration (virulence factors)o Capsuleso Cell wall componentso Enzymeso Antigenic variationo Invasinso Intracellular growtho Damage to the Host cell o Direct damageo Toxins Endotoxins Exotoxinso Lysogenic conversiono Portals of Exito Generally the same as the portals of entryo They need to be able to exit in order to infect another hostPathogenicityo Ability of a microorganism to cause diseaseVirulenceo Degree of pathogenicityo More virulence factors means the more likely it will be pathogenico Adhesion factors (help them stick to the host)o Biofilms (help bacteria hide from immune system)o Extracellular enzymes (secreted by bacteria to change the function around them)o Toxinso Exotoxins (released from the live organism)o Endotoxins (part of wall released when the organism dies)o Antiphagocytic factorso Bacterial capsuleo Chemicals (break down the membrane of macrophages that are trying to kill the pathogen)Bacterial Toxinso Endotoxins: integral part of the bacteria structureo Exotoxin: proteins encoded for by DNAo Released into the blood streamStages of Infectious Diseaseo Incubation periodo No signs and symptoms emergeo Prodromal periodo Vague general symptomso Immune system kicks ino Illnesso Most sever signs and symptomso Microbe is undergoing exponential growtho Cytokines cause fevers Immune system is trying to kill bacteria but also causes harm to self cells in the process)o Declineo Declining signs and symptomso Immune system gains an advantage over the bacteriao Convalescenceo No signs and symptomso Immune system is weakened and so it is vulnerable to another attackMovement of Pathogen Out of Hosto Usually similar to the way it came into the bodyo Most common is the oral-fecal pathway as well as respiratory dropletso Reservoirs of Infectiono Animal reservoir: Zoonotic Direct contact with the animal or the waste Bloodsucking arthropods (fleas) Humans are usually the dead-end hosto Human carriers (commonly respiratory viruses) Some individuals are asymptomatic to the infections but pass the bacteria to a new host and they start showing symptomso Nonliving reservoir (such as a cooling tower) Soil, water, food, etc.Modes of Infectious Disease Transmissiono Contact transmissiono Direct, indirect, dropletso Vehicle transmissiono Airborne, waterborne, foodborneo Vector transmissiono Mechanical, biologicalMethods of Classification of Infectious Diseaseso The body system the affect (local or systemic)o The taxonomic groups of causative agents (Staph. aureus)o Longevity and severity (acute or chronic)o How they are spread to their host (sexually transmitted diseases)Epidemiologyo Study of where and when diseases occur and how they are transmitted within