Ch 24 Microbial Diseases of the Respiratory System PDF

Ch 24 Microbial Diseases of the Respiratory System  LEARNING OBJECTIVES Describe how microorganisms are prevented from entering the respiratory system Characterize the normal microbiota of the upper and lower respiratory systems Differentiate among pharyngitis, laryngitis, tonsillitis, a...

Ch 24 Microbial Diseases of the Respiratory System  LEARNING OBJECTIVES Describe how microorganisms are prevented from entering the respiratory system Characterize the normal microbiota of the upper and lower respiratory systems Differentiate among pharyngitis, laryngitis, tonsillitis, and sinusitis List the causative agent, symptoms, prevention, preferred treatment, and laboratory identification tests for streptococcal pharyngitis, diphtheria, and otitis media. List the causative agents and treatments for the common cold. List the causative agent, symptoms, prevention, preferred treatment, and laboratory identification tests for pertussis and tuberculosis. Compare and contrast the seven bacterial pneumonias discussed in this chapter. List the causative agent, symptoms, prevention, and preferred treatment for viral pneumonia and influenza. List causative agent, mode of transmission, preferred treatment, and laboratory identification Copyright © 2006 Pearson testsas Benjamin Education, Inc., publishing for two fungal respiratory system diseases. Cummings  PowerPoint® Lecture Slide Presentation by Robert J. Sullivan, Marist College RESPIRATORY SYSTEM Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  What is Human Respiration? The human respiratory system allows one to obtain oxygen, eliminate carbon dioxide. Breathing consists of two phases, inspiration and expiration Inspiration- the process of taking in air Expiration- the process of blowing out air Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Human Respiratory System Figure 10.1 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  Organs in the Respiratory System STRUCTURE FUNCTION nose / nasal cavity warms, moistens, & filters air as it is inhaled pharynx (throat) passageway for air, leads to trachea larynx the voice box, where vocal chords are located keeps the windpipe "open" trachea (windpipe) trachea is lined with fine hairs called cilia which filter air before it reaches the lungs two branches at the end of the trachea, each bronchi lead to a lung a network of smaller branches leading from the bronchioles bronchi into the lung tissue & ultimately to air sacs the functional respiratory units in the lung alveoli where gases are exchanged Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  Components of the Upper Respiratory Tract Figure 10.2 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  Upper Respiratory Tract Functions Passageway for respiration Receptors for smell Filters incoming air to filter larger foreign material Moistens and warms incoming air Resonating chambers for voice Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  Components of the Lower Respiratory Tract Figure 10.3 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  Lower Respiratory Tract Functions: Larynx: maintains an open airway, routes food and air appropriately, assists in sound production Trachea: transports air to and from lungs Bronchi: branch into lungs Lungs: transport air to alveoli for gas exchange Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  Malfunctions & Diseases of the Respiratory System severe allergic reaction asthma characterized by the constriction of bronchioles inflammation of the lining of the bronchitis bronchioles condition in which the alveoli emphysema deteriorate, causing the lungs to lose their elasticity condition in which the alveoli pneumonia become filled with fluid, preventing the exchange of gases irregular & uncontrolled growth of lung cancer tumors in the lung tissue Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  Normal Respiratory Tract Flora  can include pathogens.  Lower respiratory system is usually sterile because of muco-ciliary escalator action.  Microbial Diseases of the Upper Respiratory System Specific areas of the upper respiratory system can become infected The infections may be caused by several bacteria and viruses, often in combination Most respiratory tract infections are self-limiting Laryngitis:  S. pneumoniae  S. pyogenes  viruses Tonsillitis:  S. pneumoniae  S. pyogenes  viruses Sinusitis: Bacteria Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Strep throat  - hemolytic - Group A (GAS) streptococci: S. pyogenes Droplet Transmission Symptoms: Sore throat, high fever, coughing, swollen LN, otitismedia may also occur The Rapid Strep Test detects presence of a unique Group A Streptococcus ag. Penicillin is used to treat streptococcal pharyngitis. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings See Fig 24.3 Complications of Strep Throat S. pyogenes causes two major nonsuppurative autoimmune complications (antibodies cross-react) 1. Acute rheumatic fever (read page 676): Short period of arthritis and fever followed in  50% of affected by rheumatic heart disease  heart valve damage  chronic valvular disease (stenosis and/or incompetence)  heart failure and/or subacute bacterial endocarditis 2. Acute poststreptococcal glomerulonephritis Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  Diphtheria  Corynebacterium diphtheriae  Pseudomembrane formation (fibrin, dead tissue and bacteria)  Not very invasive, but prophage encoded exotoxin inhibits protein synthesis  absorbed into blood  heart, nerve and kidney damage  DTaP  Boosters every 10 years Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Pseudomembrane on tonsils can lead to respiratory blockage. See Fig 24.5 Otitis Media Complication of nose and throat infections Pus accumulation causes pressure on the eardrum Bacterial causes include  S. pneumoniae (35%)  H. influenzae (20-30%)  M. catarrhalis (10-15%)  S. pyogenes (8-10%)  S. aureus (1-2%) Fig 24.6  Treated with broad-spectrum antibiotics  Incidence of S. pneumoniae reduced by vaccine Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  Common Cold About 200 different viruses can cause the common cold:   50% of cases caused by rhinoviruses (>100 types)   15-20% caused by coronaviruses Many additional cold viuses (Parainfluenza Paramyxoviridae Corona-, Coxsackie-, Echo-, Reovirus) Symptoms: Sneezing, nasal secretions and congestion Possible complications: Sinus infections, lower respiratory tract infections, laryngitis, otitis media In some children: Croup (breathing difficulty accompanied by a "barking" cough) Why no Vaccine for common cold? Incidence of colds  during cold weather, due to increased interpersonal indoor contact and/or physiological changes Antibodies are produced against the specific viruses Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  Bacterial Diseases of the Lower Respiratory System (LRS) Bacteria, viruses, and fungi cause  Bronchitis  Bronchiolitis  Pneumonia What keeps LRS sterile? Compare to Fig 24.2  Bacterial Diseases of the LRS  Pertussis (Bordetella pertussis)  Tuberculosis (Mycobacterium tuberculosis)  Common Bacterial pneumonias: S. pneumoniae, typical pneumonia H. influenza Mycoplasma pneumoniae Atypical pneumoniae Legionella pneumophila Chlamydophila psittaci Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Gram -, coccobacillus Whooping Cough Clinical presentation Bordetella pertussis, highly contagious Various toxins:  Tracheal cytotoxin damaged ciliated cells  Pertussis toxin enters blood systemic symptoms Three stages of disease 1. Catarrhal stage resembles a cold 2. Paroxysmal stage due to accumulation of mucus in trachea and bronchi  deep paroxysmal coughs (brain and eye hemorrhage) 3. Convalescence stage can last for months Laboratory diagnosis based on isolation of bacteria on enrichment and selective media, followed by serological tests Comments by Vaccination available: Copyright © 2006 Pearson DPT Education, Inc., publishing and as Benjamin new acellular DTaP Cummings Dr. Marcus Tuberculosis (Consumption)  Mycobacterium tuberculosis: transmitted from human to human via aerosol  M. bovis: 90) strains Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Mycoplasmal Pneumonia – also known as Primary Atypical Pneumonia or Walking Pneumonia  Mycoplasma pneumoniae, pleomorphic, wall-less  Mycoplasma produce small “fried-egg” colonies after two weeks’ incubation on enriched media containing horse serum and yeast extract  Common in children and young adults – often mild enough to go undiagnosed for long periods of time  Diagnosis: PCR or serological tests (IgM antibodies) Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Legionellosis or Legionnaires’ disease  Legionella pneumophila, Gram– rod  First discovered in 1976 among a group of elderly men attending an American Legion Convention in Philadelphia  The bacteria grow in water (pools, lakes, water systems of buildings, air conditioning units, etc.) then disseminated in the air  Transmission by inhaling aerosols; no person to person transmission  Diagnosis: Bacterial culture, FA tests, DNA probes  Pneumonia and pleurisy (15 - 20% mortality rate when hospitalized)  Treatment: Erythromycin Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  Viral Diseases of the Lower Respiratory System (LRS)  Several viruses can cause pneumonia as a complication of infections such as influenza, measles, or chickenpox  Etiologies are not usually identified in a clinical laboratory because of the difficulty in isolating and identifying viruses.  Viral etiology suspected if no cause determined. Respiratory Syncytial Virus:  Most common cause of pneumonia in infants – 4,500 deaths annually  Causes cell fusion (syncytium) in cell culture  Symptoms: Coughing  Diagnosis by serologic test for viruses and antibodies  Treatment: Copyright Ribavirin © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  Influenza  Influenzavirus, ssRNA, 8 segments  Symptoms: Chills, fever, headache, muscle aches (no intestinal symptoms)  Viral strains identified by antigenic differences in the H and N spikes  Also divided by antigenic differences in protein coats:  Type A → mammals and birds (most severe and extensive); currently most common antigenic variants of influenza A virus: H1N1 and H3N2  Types B and C → humans only  Viral isolates identified by HI and IF testing with monoclonal antibodies Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hemagglutinin and Neuraminidase Hemagglutinin (H) spikes used for attachment to host cells Neuraminidase (N) spikes used to release virus from cell H and N are virulence factors and antigens Mutations in H and N leads to antigenic shifts (major changes only for type A) or antigenic drifts (minor changes for all types)  natural immunity and vaccination obsolete Fig 24.15 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  Genome segments H antigen N antigen Mutation Mutation #1 #2 Mutation #1 Result of Mutation #2 ANTIGENIC DRIFT Antigenic drift Human influenza Influenza virion virion from an animal Reassortment of genome segments Host cell Antigenic ANTIGENIC SHIFT shift Only for A  Prevention and Treatment  Wide spread epidemics due to antigenic shifts Pandemics  Symptoms and Diagnosis  Complications often due to bacterial secondary infections (??)  50,000 – 70,000 deaths/year in US - also Guillain-Barré and Reye’s syndrome  Vaccine produced in chicken embryos: flu shot and nasal spray (LAIV)  Four antiviral drugs currently approved by FDA to treat acute, uncomplicated influenza CDC Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  Fungal Diseases of the Lower Respiratory System (LRS)  Fungal spores are easily inhaled; they may germinate in the lower respiratory tract  The incidence of fungal diseases has been increasing in recent years  Mycoses in the sections below can be treated with amphotericin B  Coccidioidomycosis  Pneumocystis Pneumonia Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  Coccidioidomycosis = Valley Fever  Coccidioides immitis, dimorphic  Airborne transmission  Most cases are subclinical, some get respiratory infection with flu-like symptoms  In < 1% of cases (due to predisposing factors, such as fatigue, poor nutrition, etc.): progressive, disseminated disease form resembling TB  Diagnosis: serological tests  97% of reported cases are from California and Arizona Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  Pneumocystis Pneumonia (PCP) Pneumocystis jiroveci (P. carinii), tiny fungus Commonly found in nature, healthy human lungs and animals Aerosol transmission Illness and death in newly infected infants and immunosuppressed individuals Used to be leading cause of death in AIDS patients – now preventive drug therapy Diagnosis: detection of cysts in sputum samples Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings