Slide 1Structures of the Respiratory SystemStructures of the Upper Respiratory SystemStructures of the Lower Respiratory SystemDefenses of the Respiratory SystemNormal Microbiota of the Respiratory SystemSlide 7Slide 8Streptococcal Respiratory Diseases - PathogenesisStreptococcal Respiratory Diseases – Signs and SymptomsStreptococcal Respiratory Diseases – Signs and SymptomsStreptococcal Respiratory Diseases – Signs and SymptomsStreptococcal Respiratory Diseases – EpidemiologyStreptococcal Respiratory Diseases – DiagnosisStreptococcal Respiratory Diseases – TreatmentStreptococcal Respiratory Diseases – TreatmentTuberculosis – Pathogen and Virulence FactorsTuberculosis – Pathogen and Virulence FactorsTuberculosis – PathogenesisPrimary Tuberculosis - PathogenesisPrimary Tuberculosis - PathogenesisSecondary (Reactivated) Tuberculosis - PathogenesisDisseminated Tuberculosis - PathogenesisTuberculosis – Signs and SymptomsTuberculosis – EpidemiologyTuberculosis – DiagnosisTuberculosis – TreatmentTuberculosis – PreventionInfluenza – Pathogens and Virulence FactorsInfluenza – Pathogens and Virulence FactorsInfluenza – Pathogens and Virulence FactorsInfluenza - PathogenesisInfluenza – Signs and SymptomsInfluenza – EpidemiologyInfluenza – DiagnosisInfluenza – TreatmentInfluenza – PreventionM I C R O B I O L O G YWITH DISEASES BY BODY SYSTEM SECOND EDITIONChapter 22Microbial Diseases of the Respiratory SystemTHIRDStructures of the Respiratory System•Function of the Respiratory System–Exchange of gases between the atmosphere and the blood•Respiratory system divided into two main parts–Upper respiratory system–Collects air, filters contaminants from the air, and delivers it to the lower respiratory organs–Lower respiratory systemStructures of the Upper Respiratory System•Nose – external portion of the respiratory system•Nasal cavity – lined with hairs and a ciliated mucous membrane to filter and trap particles and microbes•Pharynx – lined with a ciliated mucous membrane that pushes contaminants into the digestive systemStructures of the Lower Respiratory System•Larynx – contains the vocal cords•Trachea, bronchi, bronchioles – series of tubes that allow movement of air through to the lungs•Alveoli – Air sacs of the lungs where oxygen from air enters the blood while carbon dioxide diffuses from the blood into the alveoli to be exhaled•Diaphragm – muscle involved in breathing•“Respiratory tree”Defenses of the Respiratory System•Upper respiratory system–Aggregates of lymphoid tissue (tonsils or adenoids)–Tonsils contain cells and chemicals to combat microbes–Mucus contains antimicrobial chemicals, including defensins, lactoferrin, and lysozyme–Normal microbiota limit infection and disease by microbial antagonism•Lower respiratory system–Ciliated mucous membrane lines trachea, bronchi and bronchioles (ciliary escalator)–Alveolar macrophages–Secretory IgA in tears, saliva, and mucus–Lysozyme in tears, saliva, and mucusNormal Microbiota of the Respiratory System•Lower respiratory system–Typically microorganisms are not present•Upper respiratory system–Colonized by many types of microorganisms–Nose cooler other parts of respiratory system –H. influenzae and Veillonella–~33% of healthy people carry S. aureus in the nose–Diphtheroids in nose and nasal cavity–Many organisms colonize upper regions of pharynxStreptococcal Respiratory Diseases – Pathogen and Virulence Factors•Genus Streptococcus–Gram-positive, facultatively anaerobic cocci in chains or pairs–Streptococci differentiated by Lancefield grouping•Lancefield Group A – S. pyogenes–Major cause of bacterial pharyngitis and scarlet and rheumatic fevers–Causes a number of diseases, depending on the site of infection, the strain of bacteria, and the immune responses of the patient•M protein – destabilizes C3b; interferes with opsonization and MAC formation•Hyaluronic acid capsule – acts as an immunologic disguise•Streptokinases – lyse blood clots and allows for spreadingStreptococcal Respiratory Diseases – Pathogen and Virulence Factors•C5a peptidase – decreases movement of WBC to infection site•Pyrogenic (erythrogenic) toxins – stimulate macrophages and helper T cells to release cytokines that stimulate fever, widespread rash, and shock•Streptolysins – cause lysosomes to release their contents; lyses phagocytes and release organismsStreptococcal Respiratory Diseases - Pathogenesis•Organisms cause variety of illnesses depending on virulence factors of infectious strain •S. pyogenes frequently infects the throat, but within one week the immune responses against bacterial antigens (M protein and streptolysins) clear the organisms•Strep throat and streptococcal bronchitis typically occur when normal microbiota are depleted, large inoculum is introduced, or adaptive immunity is impaired–Usually an exogenous secondary invader•S. pyogenes can invade deeper tissues and organs through a break in mucous membranesStreptococcal Respiratory Diseases – Signs and Symptoms•Streptococcal pharyngitis (strep throat)–Back of pharynx red–Swollen lymph nodes–Purulent abscesses over tonsils–Fever–Malaise–Headache–Bacteria can spread from throat to larynx and bronchi to cause laryngitis and bronchitisStreptococcal Respiratory Diseases – Signs and Symptoms•Scarlet Fever (scarlatina)–If pharyngitis caused by strain of S. pyogenes carrying lysogenic phage for erythrogenic toxins–1-2 days of pharyngitis–Toxins released–Trigger fever–Diffuse rash that begins on chest and spreads across body–Tongue becomes strawberry red–Rash disappears after about one week and skin sloughs offStreptococcal Respiratory Diseases – Signs and Symptoms•Acute glomerulonephritis and rheumatic fever are complications of untreated strep throat–Glomerulonephritis – kidneys–Rheumatic fever – damage to heart valves and muscle (autoimmune in nature)Streptococcal Respiratory Diseases – Epidemiology •Spread via respiratory droplets•Occurs most often in winter and spring among elementary and middle school children•Is sensitive to antimicrobial drugsStreptococcal Respiratory Diseases – Diagnosis •Some estimate that <50% of patients diagnosed with strep throat actually have it; most have viral pharyngitis–Sure diagnosis requires serological testing•Immunological strep