MICROBIAL DISEASES OF THE RESPIRATORY SYSTEM Microbial Diseases of the Upper Respiratory System

Anatomical Defenses 1. Nose - coarse hairs - mucous secreting cells and cilia 2. Throat - ciliated mucous membrane - traps dust and organism - ciliated cells moves dust towards the mouth 3. Lymphoid tissues (tonsils) Normal Microbiota of the upper respiratory system: - S. epidermidis Streptococcus S. aureus H. influenzae Corynebacterium - Upper respiratory normal microbiota may include pathogens - normal microbiota suppresses the growth of pathogens by competing with nutrients & by secreting inhibitory substances. Transmission: 1. Droplet infection ( respiratory secretion) 2. Unpasteurized milk Signs & symptoms: 1. Fever 2. Local inflammation 3. Enlarged & tender lymph nodes of the neck 4. Otitis media Diagnosis: 1. Culture from throat swab 2. Agglutination diagnostic tests Treatment: Penicillin

Scarlet Fever Streptococcus pyogenes - lysogenized by a bacteriophage - produces Erythrogenic toxin - causes Pharyngitis

Signs & symptoms: 1. Fever 2. Pinkish Red Skin Rash - Hypersensitivity of the skin to the toxin 3. Spotted , Strawberry tongue Diphtheria Corybacterium diptheriae - Gram (+), non- endospore forming rod, immobile, straight or curved - Pleomorphic, Club-shaped, "Chinese characters" - Klebs-Lffler bacillus - produces an Exotoxin ( Diphtheria toxin ) Mode of transmission: 1. Droplet infection (Resistant to drying) 2. Cutaneous contact Signs & Symptoms: 1. Fever 2. Sore throat 3. Malaise 4. Swelling of the neck Bull neck - Tough grayish membrane that forms in the throat that contains fibrin, dead tissue and bacteria - Blocks passage of air to the lungs 5. Cutaneous diphtheria - Infects skin wound/ lesions - Slow healing ulcerations covered by a gray membrane Prevention: DPT ( Diptheria Pertussis Tetanus) Treatment: Penicillin and Erythromycin - controls the growth of bacteria - does not neutralize toxin Antibiotic + Diptheria antitoxin

OTITIS MEDIA Complication of colds or infections of the nose and throat Common in childhood Pus-formation in the eardrum causing it to be inflamed and painful Common pathogens: S. pneumoniae (35%) H. influenzae (20-30%) M. catarrhalis (10-15%) S. pyogenes (8-10%) S. aureus (1-2%) Treatment: broad-spectrum antibiotics Amoxicillin Incidence of S. pneumoniae reduced by vaccine VIRAL DISEASES OF UPPER RESPIRATORY SYSTEM COMMON COLD Rhinoviruses 50% Coronavirus 15-20% Other viruses 10% Immunity to cold viruses accumulate during our lifetime

Decrease incidence of cold as age increases 200 agents cause colds 113 serotypes of rhinovirus Vaccination is impractical Mode of transmission: 1. Droplet infection 2. Fomites - viruses can be found in door knobs, telephone, cards, handkerchief etc. A single virus can cause colds Signs & symptoms: 1. Sneezing 2. excessive nasal secretion 3. congestion Treatment: Antibodies are of no use Supportive BACTERIAL DISEASES OF THE LOWER RESPIRATORY SYSTEM Lower Respiratory System The Ciliary escalator keeps the lower respiratory system sterile. Bacteria, viruses, & fungi cause: Bronchitis Bronchiolitis Pneumonia

BACTERIAL DISEASES OF THE LOWER RESPIRATORY SYSTEM PERTUSSIS (WHOOPING COUGH) Bordetella pertussis - Gram-negative coccobacillus - Gram-negative, aerobic coccobacillus - Capsule Humans are its only host. Spread by coughing and by nasal drops Incubation period is 7-14 days. Occurs most with children under the age of one Children with faded immunity, normally around the age 11 through 18. Attaches to the ciliated cells in the trachea impeding their action and destroying the cells. Toxins: 1. Tracheal Cytotoxin found on its cell wall - damages ciliated cells 2. Pertussis Toxin - enters bloodstream and causes the symptoms. Stages: 1. Catarrhal stage - Mild respiratory infection symptoms - coughing, sneezing, and runny nose - Most contagious - One to two weeks 2. Paroxysmal stage - Prolonged bouts of cough - Accumulation of mucus due to damaged cilia - Infected person desperately attempts to cough off mucus - Gasping of air in between cough causes Whooping sound.

- Can result to broken ribs - Occurs several times a day for 1-6wks - Coughing fits may be followed by vomiting - Vomiting induced by coughing can lead to malnutrition and dehydration - triggered by yawning, laughing , ,stretching or yelling 3. Convalescence stage - over one to two months

Complications : *In infants: - irreversible damage to the brain (Hypoxia) - High mortality * Pneumonia Encephalitis Secondary bacterial superinfections Diagnosis: - symptoms are non-specific hence usually not diagnosed until the appearance of characteristic cough. - Culture of throat swab - PCR (polymerase chain reaction) - immunofluorescence Prevention: - DPT Treatment: - An effective antibiotic (Erythromycin or Azithromycin) - Close contacts : Antibiotics as prophylaxis BACTERIAL PNEUMONIAS

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Types of bacterial pneumonia: Gram positive - Streptococcus pneumoniae - most common cause in all age groups except in infants

- Staphylococcus aureus Gram negative - seen less frequently - Haemophilus influenzae, Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, Moraxella catarrhalis * These bacteria often live in the gut & enter the lungs when contents of the gut (vomit) are inhaled. Atypical - commonly affect teenagers and young adults - less severe Atypical Coxiella burnetti, Chlamydophila pneumoniae, Mycoplasma pneumoniae, Legionella pneumophila. Community-acquired pneumonia (CAP) - Pneumonia in a person who has not recently been hospitalized - most common type of pneumonia - causes of CAP vary depending on a persons age (CAP contnd.) - Streptococcus pneumoniae - most common cause Viruses Atypical bacteria Haemophilus influenzae Hospital-acquired pneumonia - Nosocomial pneumonia - Acquired during or after hospitalization for another illness or procedure with onset at least 72 hrs after admission. Hospital-acquired pneumonia - Seen in 5% of patients admitted for other causes. - tends to be more deadly than community-acquired pneumonia - Risk factors : Mechanical ventilation Prolonged malnutrition Underlying heart and lung diseases Decreased amounts of stomach acid Immune disturbances Other types of pneumonia: Severe acute respiratory syndrome (SARS) - SARS coronavirus Eosinophilic pneumonia - infection with a parasite - invasion of the lung by eosinophils Chemical pneumonia - Chemical pneumonitis - Chemical toxicants such as pesticides Aspiration pneumonia - Aspiration pneumonitis - aspirating foreign objects which are usually oral or gastric contents while eating or after reflux or vomiting which results in bronchopneumonia - the lung inflammation that results is not an infection but can contribute to one since the material aspirated may contain anaerobic bacteria. Aspiration pneumonia - leading cause of death among hospital and nursing home patients Laboratory examinations for pneumonia: 1. Chest x-ray - areas of opacity (seen as white) - consolidation. * Pneumonia is not always seen on x-rays either because the disease is only in its initial stages, or because it involves a part of the lung not easily seen by x-ray.

2. Chest CT (Computed Tomography) - reveal pneumonia that is not seen on chest x-ray 3. Sputum Cultures - two to three days - to confirm that the infection is sensitive to an antibiotic 4. Complete Blood Count (CBC) - a high white blood cell count Complications: * Complications are more frequently associated with bacterial pneumonia than with viral pneumonia. 1. Respiratory Failure - by triggering (ARDS) lungs quickly fill with fluid and become very stiff stiffness, combined with severe difficulties extracting oxygen due to the alveolar fluid need for mechanical ventilation 2. Sepsis and septic shock - when microorganisms enter the bloodstream and the immune system responds by secreting cytokines. - can cause liver, kidney, and heart damage 3. Pleural effusion - microorganisms infecting the lung will cause fluid to build up in the space that surrounds the lung. 4. Empysema- microorganisms present in the pleural cavity produces a pus filled fluid. 5. Lung abscess - bacteria in the lung will form a pocket of infected fluid

Pneumomoccal Pneumonia Streptococcus pneumoniae: - Gram-positive, encapsulated, diplococci - also called Pneumococcus. - causes illness in children younger than 2 years old and adults 65 years of age or older. - elderly are especially at risk of getting seriously ill and dying from this disease High risk individuals include those with the following conditions: - Chronic heart, lung, or liver disease - Sickle cell anemia - with HIV infection, AIDS. - People who have had organ transplant - taking medicines that lower their resistance to infection Transmission of pneumococcal pneumonia: - Droplet infection (Inhalation) - Between people who are ill or who carry the bacteria in their throat. - Common for people especially children, to carry the bacteria in their throats without being sick. Pneumococcal pneumonia symptoms: - may begin suddenly

- severe shaking chill which is usually followed by: High fever Cough Shortness of breath (Dyspnea) Rapid breathing (Tacypnea) Chest pains Other symptoms may include : Nausea, Vomiting , Headache , Tiredness , Muscle aches Pneumococcal pneumonia diagnosis: Symptoms, Physical exam, Lab tests , Chest x-ray Treatment: - Penicillin is the drug of choice - Amoxicillin and Erythromycin - Vancomycin or Cephalosporin Fever - aspirin or acetaminophen Supplemental oxygen Intravenous fluids Plenty of rest and take increased amounts of fluids Coughing - helps to clear the lungs of fluid Prevention: - Pneumococcal vaccine - for children and adults - 65 years old or older - serious long-term health problem - resistance to infection is lowered - babies and children younger than 2 yrs old Haemophilus influenzae Pneumonia Haemophilus influenzae (Pfeiffer's bacillus) - small, pleomorphic, gram - negative coccobacillus, some strains posses a polysaccharide capsule Haemophilus influenzae type b, or Hib - meningitis and pneumonia. age of onset : Preschool (3 month above 3yrs) peak at 3-12 months Predisposing factors: - Alcoholism - Poor nutrition - Cancer - Diabetes - Immunocompromised Transmission : - Direct contact - Inhalation of respiratory tract droplets PATHOGENESIS: Invades the nasopharyngeal mucosa Spreads to the lower respiratory tract Invades and destroys the mucous membranes Interstitial lesions Lung findings: epithelium of the smaller airways and lung interstitium show PMN or lymphatic invasion with inflammation, hemorrhagic edema and and extensive destruction. CLINICAL FEATURES: I. Prodrome - Nasopharyngeal II.Pneumonia - insidious onset with prolonged course (weeks) Fever Cough +/- productive Pleuritic chest pain Respiratory distress Complications: Bacteremia Cellulitis Epiglottitis Meningitis

Pericarditis Pyarthrosis Empysema Pleural effusion Diagnosis: Chest X-Ray - lobar consolidation - disseminated interstitial infiltration Culture & Staining: - samples include sputum throat swab, nasopharyngeal secretions, tracheal aspirate, pleural fluid, blood Treatment: Antibiotics Cefuroxime Manage complications Intubation/ventilation Treat underlying illnesses Mycoplasmal Pneumonia Mycoplasma pneumoniae: - Pleomorphic, wall-less bacteria - Primary Atypical Pneumonia or Walking Pneumonia - Common in children and young adults Symptoms: - Mild to moderate in severity that patient may remain ambulatory throughout the illness Diagnosis: - PCR or by IgM antibodies Treatment: - Second generation Macrolide - Second generation Quinolones

Legionelliosis / Legionnaires Disease Legionella pneumophila - thin, pleomorphic, flagellated Gram-negative rod - First recognized after a 1976 outbreak among a group of elderly men attending an American Legion convention in Philadelphia, Pennsylvania. Pathology: - can only be acquired from an environmental source (Water) - Transmitted by inhaling aerosols - infection never occurs between humans or humans and animals - do not inhabit the upper respiratory tract but go directly to the lungs. Symptoms: - mild cough , low fever to rapidly progressive pneumonia, coma, and death. Diagnosis: - Culture Treatment: - Erythromycin Chlamydial Pneumonia Chlamydia pneumoniae - now known as Chlamydophila pneumoniae - small bacterium that undergoes several transformations during its lifecycle - Transmitted from human to human (Droplet infection) Causes Pharyngitis, Bronchitis and atypical pneumonia[ Elderly and debilitated patients Symptoms and diagnosis: - indistinguishable from other causes of pneumonia Treatment and prognosis: - Macrolide, Quinolone

- Prognosis is excellent Viral Pneumonia Viral pneumonia - pneumonia caused by a virus - a complication of influenza, measles & chickenpox - Viral etiology suspected if no cause determined - Most common cause of pneumonia in children - Droplet infection Symptoms : - Different viruses cause different symptoms. - Fever, Non-productive cough, Rhinitis, and systemic symptoms (e.g. myalgia, headache). * Viruses also make the body more susceptible to bacterial infection; for this reason, bacterial pneumonia often complicates viral pneumonia. Viruses that commonly cause pneumonia include: Influenza virus A and B Respiratory syncytial virus (RSV) Adenoviruses (in military recruits) Human parainfluenza viruses (in children) Herpes simplex virus (HSV), mainly in newborns Varicella-zoster virus (VZV) Diagnosis: - serologic test for viruses Treatment: - largely supportive - Ribavirin.