<p> Chapter 22 Diseases of the Respiratory System</p><p>Structure 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 • Lower respiratory system</p><p>Upper Respiratory System • Function of the upper respiratory system • Collects air, filters contaminants from the air, and delivers it to the lower respiratory organs • Components of the upper respiratory system • Nose-external portion of the respiratory system • Nasal cavity-lined with hairs and a ciliated mucous membrane that help filter and trap particles and microbes • Pharynx-lined with a ciliated mucous membrane that pushes contaminants into the digestive system • Tonsils-aggregations of lymphoid tissue</p><p>Lower Respiratory System • Components 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-small 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 • Protective components of the lower respiratory system include a ciliated mucous membrane, alveolar macrophages, and secretory antibodies</p><p>Normal Microbiota of the Respiratory System • Lower Respiratory System • Typically microorganisms are not present • Upper Respiratory System • The normal microbiota remove nutrients and produce substances that limit growth of pathogenic organisms • Some normal microbiota are opportunistic pathogens • Examples of normal microbiota • Hemophilus influenzae can colonize the nose • Staphylococcus aureus is present as normal microbiota in some individuals without causing disease • Diphtheroids can colonize the nose and nasal cavity</p><p>Bacterial Diseases of the Upper Respiratory System • Bacteria can infect the upper respiratory system and cause such conditions as sore throat • Examples of bacterial upper respiratory infections • Streptococcal respiratory diseases • Diphtheria</p><p>Streptococcal Respiratory Diseases • Cause: Group A streptococci (S. pyogenes) • Virulence factors: M proteins, hyaluronic acid capsule, streptokinases, C5a peptidase, pyrogenic toxins, streptlysins • Portal of entry: Upper respiratory tract via respiratory droplets • Signs/Symptoms: Sore throat, difficulty swallowing; may progress to scarlet or rheumatic fever • Susceptibility: Children typically most susceptible • Treatment: Penicillin is the standard treatment • Prevention: Infectious individuals are infectious for two days after treatment and should stay at home</p><p>Diphtheria • Cause: Cornybacterium diphtheriae • Virulence factor: Diphtheria toxin prevents polypeptide synthesis and causes cell death • Portal of entry: Spread person to person via respiratory droplets or skin contact • Signs/Symptoms: Sore throat, oozing fluid that hardens into a pseudomembrane that can obstruct airways • Susceptibility: Immunocompromised or nonimmune individuals develop symptomatic infections • Treatment: Administration of antitoxin and antibiotics • Prevention: Immunization</p><p>Bacterial Diseases of the Sinuses and Ears • Bacteria present in the pharynx can infect the sinuses or middle ear and cause disease • Examples of infections of the sinuses and ears • Sinusitis • Otitis media</p><p>Sinusitis • Cause: Various bacteria such as Streptococcus pneuomoniae, Staphylococcus aureus, Haemophilus influenzae, and Moraxella catarrhalis • Portal of entry: Bacteria in the pharynx spread to the sinuses via their connection with the throat • Signs/Symptoms: Pain and pressure of the affected sinus accompanied by malaise • Susceptibility: Adults are most often affected • Diagnosis: Symptoms are often diagnostic • Prevention: No known ways to prevent sinusitis</p><p>Otitis Media • Cause: Various bacteria such as Streptococcus pneuomoniae, Staphylococcus aureus, Haemophilus influenzae, and Moraxella catarrhalis • Portal of entry: Bacteria in the pharynx spread to the middle ear via the auditory tubes • Signs/Symptoms: Severe pain in the ears • Susceptibility: Children are most often affected • Diagnosis: Symptoms are often diagnostic • Treatment: Antimicrobial drugs • Prevention: Various measures may be taken to prevent otitis media such as tonsil removal and placement of plastic tubes in the ear to allow drainage</p><p>Viral Diseases of the Upper Respiratory System • Viral respiratory diseases are some of the most common human diseases • The common cold is the primary viral disease of the upper respiratory system</p><p>Common Cold • Cause: Rhinoviruses are the most common although numerous viruses cause colds • Portal of entry: Transmitted via coughing/sneezing, fomites, or person-to- person contact • Signs/Symptoms: Sneezing, runny nose, congestion, sore throat, malaise, and cough • Susceptibility: Children acquire colds most often • Diagnosis: Symptoms are usually diagnostic • Treatment: Supportive care for symptoms • Prevention: Antisepsis and disinfection of fomites</p><p>Bacterial Diseases of the Lower Respiratory System • Lower respiratory organs are usually axenic • When bacterial infection of the lower respiratory system occurs life- threatening illness can result • Examples of bacterial infections of the lower respiratory system • Bacterial pneumonia • Legionnaire’s disease • Pertussis (whooping cough) • Tuberculosis</p><p>Bacterial Pneumonias • Pneumonia is inflammation of the lungs accompanied by fluid filled alveoli and bronchioles • Pneumonia can be categorized by the affected region or the organism causing the disease • Lobar pneumonia-involves entire lobes of the lungs • Mycoplasmal pneumonia-caused by the bacterium Mycobacterium • Nosocomial pneumonia-pneumonia acquired in a health care setting • Bacterial pneumonias are the most serious of the pneumonias and the most frequent in adults</p><p>Pneumococcal Pneumonia • Cause: Streptococcus pneumoniae • Virulence factors: Adhesins, capsule, pneumolysin • Portal of entry: Inhalation • Signs/Symptoms: Fever, chills, congestion, cough, chest pain, and short, rapid breathing • Incubation period: One to three days • Susceptibility: Immunocompromised individuals • Treatment: Penicillin is the drug of choice • Prevention: Vaccination</p><p>Primary Atypical (Mycoplasmal) Pneumonia • Cause: Mycoplasma pneumoniae • Virulence factors: Adhesion protein • Portal of entry: Nasal secretions among individuals in close contact • Signs/Symptoms: Atypical symptoms including fever, malaise, sore throat, excessive sweating • Incubation period: One to four weeks • Susceptibility: High school and college students • Treatment: Tetracycline and erythromycin • Prevention: Difficult to prevent because individuals can be infective despite lack of symptoms</p><p>Klebsiella pneumonia • Cause: Klebsiella pneumoniae • Virulence factors: Capsule • Portal of entry: Inhalation • Signs/Symptoms: Typical pneumonia symptoms combined with a thick, bloody sputum and recurrent chills • Incubation period: One to three days • Susceptibility: Hospitalized individuals • Treatment: Cephalosporins and supportive care • Prevention: Aseptic technique by health care workers</p><p>Other Bacterial Pneumonia • Cause: Hemophilus influenzae, Staphylococcus aureus, Yersinia pestis, and Chlamydia species • Portal of entry: Inhalation, also via blood with Y. pestis • Signs/Symptoms: Typical pneumonia symptoms along with frothy, bloody sputum in the case of Y. pestis • Incubation period: Variable depending on cause although Y. pestis can produce symptoms in hours • Susceptibility: Typically young children • Treatment: Antibiotic treatment • Prevention: Good hygiene; vaccine available for H. influenzae</p><p>Legionellosis (Legionnaire’s Disease) • Cause: Legionella pneumophila • Portal of entry: Inhalation of Legionella-filled vesicles • Signs/Symptoms: Typical pneumonia symptoms and possible complications of the gastrointestinal tract, CNS, liver, and kidneys • Susceptibility: Includes the elderly, smokers, immunocompromised individuals • Diagnosis: Presence of Legionella or antibodies against the bacterium • Treatment: Erythromycin is the drug of choice • Prevention: Reduce bacterial presence in water</p><p>Tuberculosis • Signs and Symptoms • Initial symptoms include minor cough and mild fever • Later symptoms include difficulty breathing, chest pain, wheezing, and coughing up blood • Pathogen and Virulence Factors • Mycobacterium tuberculosis is the causative agent • Presence of virulence factors aid in pathogenesis • Mycolic acid present in the cell wall has various effects • Cord factor is required for mycobacteria to cause disease • Pathogenesis • M. tuberculosis can remain viable for long periods in aerosol drops due to protection of the mycolic acid in the cell wall • Three types of tuberculosis • Primary tuberculosis-initial case of tuberculosis disease • Secondary tuberculosis-reestablished tuberculosis • Disseminated tuberculosis-tuberculosis involving multiple systems • Epidemiology • Immunocompromised individuals are most at risk • Tuberculosis is the leading killer of HIV+ individuals • Diagnosis, Treatment, and Prevention • Tuberculin skin test identifies previous exposure to M. tuberculosis • Doesn’t distinguish between active disease, chronic carriers, or those who have been vaccinated • Treatment requires multi-drug regimen • Prevention includes vaccination in some countries and surveillance of patients to limit spread of disease </p><p>Pertussis (Whooping Cough) • Cause: Bordetella pertussis • Virulence factors: Pertussis toxin, adenylate cyclase toxin, dermonecrotic toxin, and tracheal cytotoxin • Portal of entry: Inhalation of bacteria in airborne droplets • Signs/Symptoms: Catarrhal stage: symptoms resemble a cold; Paroxysmal stage: characteristic severe cough; Convalescent stage: cough slowly subsides • Susceptibility: Unimmunized children • Treatment: Combination antibiotic therapy • Prevention: DTaP vaccine</p><p>Inhalation Anthrax • Cause: Bacillus anthracis • Virulence factors: Capsule, anthrax toxin • Portal of entry: Inhalation of endospores • Signs/Symptoms: Initial symptoms resemble a cold or flu but progress to severe coughing, shortness of breath, shock, and death • Diagnosis: Identification of bacteria in sputum • Treatment: Various antimicrobials • Prevention: Anthrax vaccine available to military personnel, researchers, health care workers dealing with anthrax patients</p><p>Influenza • Signs and Symptoms • Sudden fever, pharyngitis, congestion, cough, myalgia • Pathogens and Virulence Factors • Influenza virus types A and B are the causative agents • Strains named as follows: Type/Location /Month (as number)/Year (HA and NA antigen types) • Hemagglutinin and neuraminidase mutations produce the ever changing array of strains • Mutations occur via two main processes • Antigenic drift • Antigenic shift • Signs and Symptoms • Sudden fever, pharyngitis, congestion, cough, myalgia • Pathogens and Virulence Factors • Influenza virus types A and B are the causative agents • Strains named as follows: Type/Location /Month (as number)/Year (HA and NA antigen types) • Hemagglutinin and neuraminidase mutations produce the ever changing array of strains • Mutations occur via two main processes • Antigenic drift • Antigenic shift • Pathogenesis • Symptoms of influenza are produced by the immune response to the virus • Flu patients are susceptible to secondary bacterial infections due to virally produced damage to the lung epithelium • Epidemiology • Influenza is transmitted via inhalation of airborne viruses or by self-inoculation • Complications occur most often in the elderly, children, and those with chronic diseases • Diagnosis • Signs and symptoms during a community-wide outbreak are often diagnostic • Treatment • Four drugs are approved to treat influenza • Amantadine, rimantadine, oseltamivir, zanamivir • Treatment also involves supportive care to relieve symptoms • Prevention • Immunization with a multivalent vaccine</p><p>Severe Acute Respiratory Syndrome (SARS) • Cause: SARS-associated coronovirus • Portal of entry: Respiratory droplets enter through mucous membranes via close person-to-person contact • Signs/Symptoms: High fever, head and body aches, malaise, dry cough, pneumonia develops • Incubation period: Typically two to seven days • Susceptibility: Some individuals may be genetically susceptible • Treatment: Primarily supportive care • Prevention: Quarantine infected persons, good hygiene</p><p>Respiratory Syncytial Virus Infection • Most common childhood respiratory disease • Signs and Symptoms • Fever, runny nose, coughing, in babies or immunocompromised individuals • Mild coldlike symptoms occur in older children and adults • Pathogen • Respiratory syncytial virus (RSV) • Pathogenesis • Formation of syncytia can help viruses evade the immune system and also infect new cells • Epidemiology • Transmission occurs via close contact with infected persons • Diagnosis, Treatment, and Prevention • Diagnosis of RSV infection made by immunoassay combined with signs of respiratory distress • Supportive treatment for young children • Prevention includes aseptic technique of health care workers and day care employees</p><p>Hantavirus Pulmonary Syndrome (HPS) • Cause: Hantavirus strains • Portal of entry: Inhalation of infected rodent excrement or saliva • Signs/Symptoms: High fever, head and body aches, malaise, dry cough, pneumonia develops • Incubation period: Fourteen to thirty days • Susceptibility: Individuals exposed to rodents in endemic areas • Treatment: Supportive care • Prevention: Avoidance of rodent droppings</p><p>Other Viral Respiratory Diseases • Other viruses cause respiratory disease in children, the elderly, or immunocompromised individuals • Cytomegalovirus • Metapneumovirus • Estimated to be the second most common cause of viral respiratory disease behind rhinoviruses • Parainfluenzaviruses • Three strains cause croup and viral pneumonia • Occurs primarily in young children</p><p>Fungal Infections of the Lower Respiratory System • Certain systemic mycoses can involve the respiratory system • Coccidioidomycosis • Blastomycosis • Histoplasmosis • Pneumocystis pneumonia is a common fungal pneumonia of AIDS patients</p><p>Coccidioidomycosis • Commonly called valley fever • Cause: Coccidioides immitis • Portal of entry: Inhalation of arthroconidia in the soil • Signs/Symptoms: Symptoms can resemble pneumonia or tuberculosis; infection can become systemic in immunocompromised persons with various symptoms • Epidemiology: Endemic to southwestern U.S. and Mexico • Diagnosis: Presence of spherules in clinical specimens • Treatment: Amphotericin B • Prevention: Protective masks can prevent exposure to arthroconidia for those in occupations with high risk</p><p>Blastomycosis • Cause: Coccidioides immitis • Portal of entry: Inhalation of fungal spores in dust • Signs/Symptoms: Flulike symptoms: systemic infections can produce painless lesions on the face and upper body or purulent lesions on various organs • Epidemiology: Endemic to southeastern U.S. and Canada • Diagnosis: B. dermatitidis in clinical samples • Treatment: Amphotericin B</p><p>Histoplasmosis • Most common fungal systemic disease of humans • Cause: Histoplasmosis capsulatum • Portal of entry: Inhalation • Signs/Symptoms: Dry cough with blood tinged sputum and skin lesions • Epidemiology: Endemic to eastern U.S. but also found in parts of Africa and Central and South America • Susceptibility: Children and those exposed to soil • Diagnosis: Presence of budding yeast in macrophages • Treatment: Amphotericin B • Prevention: Minimize exposure to soil</p><p>Pneumocystis Pneumonia (PCP) • Cause: Pneuocystis jiroveci (Previously P. carinii) • Portal of entry: Inhalation of droplets containing the fungus • Signs/Symptoms: Difficulty breathing, mild anemia, hypoxia, and fever • Susceptibility: Immunocompromised patients particularly those with AIDS • Treatment: Trimethoprim and sulfamethoxazole (TMP-SMX) • Prevention: Cannot avoid the fungus but maintenance of a healthy immune system limits disease</p>