Transcript Chapter 24
MICROBIOLOGY Chapter 24 Microbial Diseases of the Respiratory System Dr. Abdelraouf A. Elmanama Ph. D Microbiology Medical Technology Department, Faculty of Science, Islamic University-Gaza 2008 Microbial Diseases of the Upper Respiratory System • Laryngitis: S. pneumoniae, S. pyogenes, viruses • Tonsillitis: S. pneumoniae, S. pyogenes, viruses • Sinusitis: Bacteria • Epiglottitis: H. influenzae 2008 Upper Respiratory System • Upper respiratory normal microbiota may include pathogens 2008 Figure 24.1 Streptococcal pharyngitis (Strep throat) • Streptococcus pyogenes • Resistant to phagocytosis • Streptokinases lyse clots • Streptolysins are cytotoxic • Diagnosis by indirect agglutination 2008 Figure 24.3 Scarlet Fever • Streptococcus pyogenes • Pharyngitis • Erythrogenic toxin produced by lysogenized S. pyogenes 2008 Figure 24.4 Diphtheria • Corynebacterium diphtheriae: Gram-positive rod • Diphtheria membrane of fibrin, dead tissue, and bacteria • Diphtheria toxin produced by lysogenized C. diphtheriae • Prevented by DTaP and Td vaccine (Diphtheria toxoid) • Cutaneous diphtheria: Infected skin wound leads to slow healing ulcer 2008 Diphtheria 2008 Figure 24.6 Otitis Media • S. pneumoniae (35%) • H. influenzae (20-30%) • M. catarrhalis (10-15%) • S. pyogenes (8-10%) • S. aureus (1-2%) • Treated with broad-spectrum antibiotics • Incidence of S. pneumoniae reduced by vaccine 2008 Otitis Media 2008 Figure 25.7 Common cold • Rhinoviruses (50%) • Coronaviruses (15-20%) • Rhinoviruses attached to ICAN-1 on nasal mucosa 2008 Microbial Diseases of the Lower Respiratory System • Bacteria, viruses, & fungi cause: • Bronchitis • Bronchiolitis • Pneumonia 2008 Lower Respiratory System • The ciliary escalator keeps the lower respiratory system sterile. 2008 Figure 24.2 Pertussis (Whooping Cough) • Bordetella pertussis: Gram-negative coccobacillus • Capsule • Tracheal cytotoxin of cell wall damaged ciliated cells • Pertussis toxin • Prevented by DTaP vaccine (acellular Pertussis cell fragments) 2008 Figure 24.8 Pertussis (Whooping Cough) • Stage 1: Catarrhal stage, like common cold • Stage 2: Paroxysmal stage: Violent coughing sieges • Stage 3: Convalescence stage 2008 Tuberculosis • Mycobacterium tuberculosis: Acid-fast rod. Transmitted from human to human • M. bovis: <1% U.S. cases, not transmitted from human to human • M. avium-intracellulare complex infects people with late stage HIV infection 2008 Figure 24.9 Tuberculosis 2008 Figure 24.10.1 Tuberculosis 2008 Figure 24.10.2 Tuberculosis 2008 Figure 24.10.3 Tuberculosis • Treatment of Tuberculosis: Prolonged treatment with multiple antibiotics • Vaccines: BCG, live, avirulent M. bovis. Not widely used in U.S. 2008 Tuberculosis • Diagnosis: Tuberculin skin test screening • + = current or previous infection • Followed by X-ray or CT, acid-fast staining of sputum, culturing bacteria 2008 Figure 24.11 Tuberculosis 2008 Figure 14.11c Tuberculosis 2008 Figure 24.12 Pneumomoccal Pneumonia • Streptococcus pneumoniae: Gram-positive encapsulated diplococci • Diagnosis by culturing bacteria • Penicillin is drug of choice 2008 Figure 24.13 Pneumomoccal Pneumonia 2008 Haemophilus influenzae Pneumonia • Gram-negative coccobacillus • Alcoholism, poor nutrition, cancer, or diabetes are predisposing factors • Second-generation cephalosporins 2008 Mycoplasmal Pneumonia • Mycoplasma pneumoniae: pleomorphic, wallless bacteria • Also called primary atypical pneumonia and walking pneumonia • Common in children and young adults • Diagnosis by PCR or by IgM antibodies 2008 Figure 24.14 Mycoplasmal Pneumonia 2008 Figure 11.19a, b Legionellosis • Legionella pneumophila: Gram-negative rod • L. pneumophila is found in water • Transmitted by inhaling aerosols, not transmitted from human to human • Diagnosis: culturing bacteria • Treatment: Erythromycin 2008 Psittacosis (Ornithosis) • Chlamydia psittaci: gram-negative intracellular bacterium • Transmitted by elementary bodies from bird dropping to humans • Reorganizes into reticulate body after being phagocytized • Diagnosis: culturing bacteria in eggs or cell culture • Treatment: Tetracycline 2008 Chlamydial Pneumonia • Chlamydia pneumoniae • Transmitted from human to human • Diagnosis by FA test • Treatment: Tetracycline 2008 Q fever • Mycoplasma pneumoniae: pleomorphic, wall-less bacteria • Also called primary atypical pneumonia and walking pneumonia • Common in children and young adults • Diagnosis by PCR or by IgM antibodies 2008 Q fever 2008 Figure 24.15 Viral Pneumonia • Viral pneumonia as a complication of influenza, measles, chickenpox • Viral etiology suspected if no cause determined • Respiratory Syncytial Virus (RSV) • Common in infants; 4500 deaths annually • Causes cell fusion (syncytium) in cell culture • Symptoms: coughing • Diagnosis by serologic test for viruses and antibodies • Treatment: Ribavirin 2008 Influenza • Chills, fever, headache, muscle aches (no intestinal symptoms) • 1% mortality due to secondary bacterial infections • Treatment: Amantadine • Vaccine for high-risk individuals 2008 Influenza • Hemagglutinin (H) spikes used for attachment to host cells • Neuraminidase (N) spikes used to release virus from cell 2008 Influenza 2008 Figure 24.16 Influenza • Antigenic shift • Changes in H and N spikes • Probably due to genetic recombination between different strains infecting the same cell • Antigenic drift • Mutations in genes encoding H or N spikes • May involve only 1 amino acid • Allows virus to avoid mucosal IgA antibodies 2008 Influenza serotypes • A: causes most epidemics, H3N2, H1N1, H2N2 • B: moderate, local outbreaks • C: mild disease 2008 Histoplasmosis • Histoplasma capsulatum, dimorphic fungus (a) 37˚ 2008 (a) >35˚ Figure 24.17 Histoplasmosis • Transmitted by airborne conidia from soil • Diagnosis by culturing fungus • Treatment: amphotericin B 2008 Figure 24.18 Coccidioidomycosis • Coccidioides immitis 2008 Figure 24.19 Coccidioidomycosis • Transmitted by airborne arthrospores • Diagnosis by serological tests or DNA probe • Treatment: amphotericin B 2008 Figure 24.20 Pneumocystis Pneumonia • Pneumocystis jiroveci (P. carinii) found in healthy human lungs • Pneumonia occurs in newly infected infants & immunosuppressed individuals • Treatment: Timethoprimsulfamethoxazole 2008 Figure 24.22 Pneumocystis 1 The mature cyst contains 8 intracystic bodies. Cyst 2 The cyst ruptures, releasing the bodies. Intracystic bodies 5 Each trophozoite develops into a mature cyst. 4 The trophozoites divide. 3 The bodies develop into trophozoites. Trophozoite 2008 Figure 24.21 Blastomycosis • Blastomyces dermatitidis, dimorphic fungus • Found in soil • Can cause extensive tissue destruction • Treatment: amphotericin B 2008 Opportunistic fungi involved in respiratory disease: • Aspergillus • Rhizopus • Mucor Mucor rouxii 2008 Figure 12.2b, 12.4