Upper Respiratory Tract PDF

Anatomy of the Respiratory System Microbial Agents of the Two Anatomic Divisions: Upper Respiratory Tract...

Anatomy of the Respiratory System Microbial Agents of the Two Anatomic Divisions: Upper Respiratory Tract Upper Respiratory Tract Introduction Nasal cavity, pharynx, epiglottis, larynx, and structures associated with them Charlie A. Clarion, RMT, MD, FPCP, DPCCP Fellow, Philippine College of Physicians Lower Respiratory Tract Diplomate, Philippine College of Chest Physicians Trachea, bronchus, bronchioles, Fellow, MSc in Epidemiology (Clinical Epidemiology) alveoli Structures of the Upper Respiratory System Structures of the Lower Respiratory System The Respiratory Tract as a Continuum The Normal Flora of the Respiratory Tract Pathogens that Gain Entry via the Upper Generalization Respiratory Tract 1. Although many organisms are restricted to the surface epithelium, some spread to other parts of the body before returning to the respiratory tract, oropharynx and salivary glands. 2. Two groups of pathogens can be distinguished: professional and secondary invaders. 3. Professional invaders are those that successfully infect the normal healthy respiratory tract. They generally possess specific properties that enable them to evade local host defenses such as the attachment mechanisms of respiratory viruses. Secondary invaders cause disease only when host defenses are already impaired. 4. The symptoms of an upper respiratory tract infection include fever, rhinitis, pharyngitis or sore throat. It is NOT just respiratory pathogens that cause these symptoms. Two Types of Respiratory Invaders: Microbial Diseases of the Upper Professional or Secondary Respiratory System Bacterial Agents Streptococcal Pharyngitis Streptococcus pyogenes Pinpoint, grayish colonies, Etiology: Streptococcus surrounded by a zone of M-protein → important factor in the development of pyogenes beta hemolysis rheumatic fever Gram positive cocci in pairs or long chains Group A strain: with hyaluronic acid capsules (antiphagocytic) Facultative anaerobe Beta hemolytic, grow best at 10% CO2 and 37C PYR-positive (hydrolysis of L- pyrrolidony 1-B-naphthylamide) Bacitracin susceptible Virulence Factors of S. pyogenes Neutrophil Extracellular Traps Virulence Factors Biologic Effect Network of extracellular strings Lyses leukocytes; platelets and erythrocytes; stimulates release of of DNA that bind pathogenic Streptolysin S microbes lysosomal enzymes; non immunogenic Streptolysin O Lyses leukocytes; platelets and erythrocytes; stimulates release of lysosomal enzymes, immunogenic Streptokinase Lyses blood clots; facilitates spread of bacteria in tissues (used in the treatment of acute MI) DNAse Destroys neutrophil extracellular traps (which function to kill extracellular microbes) C5a peptidase Degrades complement C5a C5a Peptidase Virulence Factors of S. pyogenes Streptococcal Pharyngitis Degrades complement C5a Virulence Factors Biologic Effect Transmission: Direct person-to- person Capsule Antiphagocytic Lipoteichoic acid Binds to epithelial cells Presentation Usually high fever, malaise, headache F protein Mediates adherence to epithelial cells and internalization Hyperemic tonsils with yellowish exudates M protein Adhesion; Antiphagocytosis activity Enlarged and tender submandibular lymph nodes Peritonsillar abscess, retropharyngeal abscess May be asymptomatic Streptococcal Pharyngitis Laboratory Diagnosis Treatment Non suppurative complications: Culture of throat swab, pus, CSF, Antibiotics Acute rheumatic fever: or blood, on blood agar plates Penicillin G Antibody to M protein cross reacting Macrolide: for penicillin-allergic to heart valves patients Most serious sequela of S. pyogenes Antigen Detection Tests Cephalosporin Acute glomerulonephritis: EIA, agglutination test immune complex Serologic Tests ASO: respiratory disease Anti-DNase B and Anti- hyaluronidase: skin infections Causes of Acute Pharyngitis Diphtheria Non-Exudative Exudative Etiology: Corynebacterium diphtheriae Rhinovirus Streptococcus pyogenes Gram-positive rod with irregular Adenovirus Mixed anaerobic infection swelling at one end → club-shaped appearance Respiratory syncytial virus (Vincent’s angina; Palisade arrangement peritonsillar abscess) Adenovirus With metachromatic granules (staining deeply with aniline dyes) → Herpes simplex virus beaded appearance Epstein Barr virus Corynebacterium diphtheriae Agar with potassium tellurite: brown to black colonies with brown- black halo Pathogenesis Laboratory Diagnosis Laboratory Diagnosis Diphtheria toxin: Specimen: dacron swabs from the nose, Modified Elek Heat-labile, single-chain, three- throat or other suspected lesions before immunoprecipitation method domain polypeptide starting antibiotics Positive: precipitin bands LD: 0.1 ug/kg body weight between the disks and bacterial growth Presentation Transport: Amies medium Sore throat, low-grade fever, Agar: Tellurite plate (cystine-tellurite blood PCR-based methods prostration agar, or modified Tinsdale’s medium) at Pseudomembrane (tough grayish 37C, in 5% CO2 ELISA membrane in the throat containing fibrin, dead tissue, and bacterial Immunochromatographic strip cells)→ dyspnea from obstruction Treatment Otitis Media Epiglottitis Rapid suppression of toxin Middle ear infection Inflammation of the epiglottis or nearby structures including Antibiotics: penicillin, macrolides More common in children arytenoids, aryepiglottic folds, and Arrest toxin production vallecula Complication of common cold or Life-threatening infection that Antitoxin: 20,000 to 120,000 u IM or IB any infection of the nose/throat causes profound swelling of the Neutralize circulating toxin only (not bound to tissue) upper airways → asphyxia and respiratory arrest Vaccination (Prevention) Etiology: S. pneumoniae (most common), non-encapsulated H. Etiology: H. influenzae type b DPT vaccination (active immunization) influenzae, M. catarrhalis, S. (most common), S. pyogenes, S. pyogenes pneumoniae, S. aureus, P. aeruginosa, Candida, viruses Treatment Adenoviridae Secure the airway by Human adenoviruses: 51 Epiglottitis | Pediatric Radiology Reference Article | Pediatric Imaging | @pedsimaging Endotracheal intubation serotypes Tracheostomy Use of corticosteroids: reduce Viral Agents Only virus with fiber: Penton Fiber edema Antibiotics Predilection for mucosal epithelial cells of the respiratory, gastrointestinal and conjunctiva Adenoviridae Adenoviridae Rhinovirus Transmission: Respiratory, fecal- Histopathology: Cowdry Type Family: picornaviridae oral, direct contact (eye) B intranuclear inclusions Site of latency: replication in Circumscribed and multiple Most common cause of common oropharynx colds (rhinovirus, coronavirus) Disease More than 100 serotypes → Pharyngitis, keratoconjunctivitis, particularly no immunity Coryza, Bronchiolitis, Atypical pneumonia Hemorrhagic cystitis, Killed by gastric acid so when Acute Gastroenteritis Disseminated disease swallowed cannot cause GI disease Rhinovirus Treatment Supportive: antihistamines, cough suppressant, hydration No vaccine available THANK YOU!