Microbial Diseases Of The Respiratory System

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-Löffler 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

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

the

- 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 person’s 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 / Legionnaire’s 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.