Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Marine microorganism wikipedia , lookup
Antimicrobial surface wikipedia , lookup
Urinary tract infection wikipedia , lookup
Bacterial morphological plasticity wikipedia , lookup
Triclocarban wikipedia , lookup
Neonatal infection wikipedia , lookup
Infection control wikipedia , lookup
Human microbiota wikipedia , lookup
Coccidioidomycosis wikipedia , lookup
Anaerobic infection wikipedia , lookup
Page 1 of 14 Dr. RAJENDRAN’S INSTITUTE OF MEDICAL EDUCATION +91 93888 5552 PNEUMONIA AND LUNG ABSCESS (57 MCQs) 1) What type of cells line the large airways? a. IgA secreting cells b. Ciliated columnar epithelial cells c. Type 1 and 2 cells d. Macrophages Ans - B 80% of the cells lining the central airways are ciliated, pseudostratified, columnar epithelial cells. Each ciliated cell contains about 200 cilia (See figure below). The cilia beat at 1000 times per minute. There is a fast forward stroke and a slower backward recovery. Ciliary motion is coordinated so that each wave is propagated toward the oropharynx. The cilia are covered by a liquid film that is 5 to 10 um thick. It is composed of two layers. The outer layer (or gel layer) is viscous. It traps deposited particles. The cilia beat in the less viscous inner layer (sol layer). During the forward stroke, the tips of the cilia just touch the viscous gel and propel it toward the oropharynx. During recovery, the cilia move entirely within the low-resistance sol layer. Ciliated www.medicinemcq.com Page 2 of 14 cells are interspersed with mucus-secreting cells in the trachea and bronchi but not in the bronchioles. 2) Which is present in the fluid lining the alveolar walls? a. Surfactant b. Fibronectin c. Immunoglobulin d. Macrophages e. All of the above Ans - E The epithelial lining fluid contains surfactant, fibronectin, and immunoglobulin. Fibronectin is a large surface protein secreted by macrophages and platelets. Fibronectin is the receptor for the normal gram-positive flora of the oropharynx. Fibronectin is a commonly used receptor for binding by pathogens. www.medicinemcq.com Page 3 of 14 The immunoglobulins opsonize or lyse pathogens deposited on the alveolar surface. The alveolar macrophages, lymphocytes, and a few polymorphonuclear leukocytes are loosely attached to the lining cells or lying free within the lumen. From blood to air, the alveolar walls consist of the endothelium that lines the capillaries, the capillary basement membrane, the interstitial tissue, the alveolar basement membrane, the alveolar lining epithelial cells (flattened type 1 pneumocytes that cover 95% of the alveolar surface or rounded, granular, surfactant-producing type 2 pneumocytes), and epithelial lining fluid. 3) What keeps the lower respiratory tract normally sterile? a. Sneezing b. Cough reflex c. Ciliary action d. Alveolar macrophages e. All of the above Ans - E Infectious particles deposited on the nasal surfaces are removed by sneezing. www.medicinemcq.com Page 4 of 14 Reflex closure of the glottis and cough protect the lower respiratory tract. Impairment of the cough reflex increases the risk of pneumonia. Causes of loss or suppression of the cough reflex include coma, anesthesia, neuromuscular disorders, drugs, and chest pain. Those particles deposited on the tracheobronchial surface are swept by ciliary motion toward the oropharynx. Mucociliary dysfunction increases the risk of pneumonia. Causes of mucociliary dysfunction include cigarette smoke, inhalation of hot or corrosive gases, viral infections, or genetic disturbances (e.g., the immotile cilia syndrome or Kartagener syndrome and cystic fibrosis). Particles that bypass the above defenses in the airways and get deposited on the alveolar surface are cleared by phagocytic cells and humoral factors. Alveolar macrophages are the major phagocytes in the lower respiratory tract. Some phagocytosed microorganisms are killed. Other microorganisms can persist within the macrophage (e.g., Mycobacterium tuberculosis, Legionella). Dysfunction of alveolar macrophages increases the risk of pneumonia. See figure below. The common pathogenetic mechanism is attachment of the organisms to the upper respiratory tract epithelium. This is followed by necrosis of the cells lining the respiratory tract, an inflammatory response and outpouring of fluid into alveolar spaces. www.medicinemcq.com Page 5 of 14 4) Which statement(s) is/are true? a. 80% of the cells lining the central airways are ciliated b. Epithelial lining fluid contains immunoglobulin c. Lower respiratory tract is normally sterile d. All Ans - D When small numbers of low-virulence microbes are deposited in the lungs, immune defenses (e.g., mucociliary escalator, antimicrobial proteins in airway surface liquid and alveolar macrophages) eradicate the infection. In contrast, numerous or more virulent microbes elicit an inflammatory response that helps to rid the lungs of infecting microbes. During pulmonary infection, neutrophils migrate out of the pulmonary capillaries and into the air spaces. Neutrophils kill ingested microbes with reactive oxygen species (e.g., hypochlorite), antimicrobial proteins (e.g., bactericidal permeability-inducing protein and lactoferrin), and degradative enzymes (e.g., elastase). Acute inflammation is an essential immune response in the lungs. At the same time, it also contributes directly to lung injury and abnormal pulmonary function. The neutrophil products such as reactive oxygen species and proteases released to kill microbes also kill host cells and damage host tissues. 5) Defects in cell-mediated immunity leads to increased infections with all except a. Mycobacteria b. Herpesviruses www.medicinemcq.com Page 6 of 14 c. Pneumocystis carinii d. Pyogenic bacteria Ans - D Cell-mediated immune defects lead to increased infections with intracellular microbes such as mycobacteria and herpesviruses as well as with microorganisms of very low virulence, such as Pneumocystis carinii. Neutrophil and complement defects and humoral immunodeficiency typically lead to an increased incidence of infections with pyogenic bacteria. 6) What is pneumonia? a. Any infection of the lung parenchyma b. Infection of alveoli c. Infection below trachea d. Infection below bronchi with or without alveolar involvement Ans - A Pneumonia is broadly defined as any infection of the lung parenchyma (although the same term is used for many interstitial lung diseases that are not infectious in origin, such as usual interstitial pneumonia). Pneumonias can be classified by the specific etiologic agent (e.g., pneumococcal, staphylococcal) or by the clinical setting in which the infection occurs (e.g., community acquired or acquired in a hospital). Classifying into community acquired pneumonia or nosocomial www.medicinemcq.com Page 7 of 14 pneumonia narrows the list of suspected pathogens for giving empirical antimicrobial therapy. See table below. THE PNEUMONIA SYNDROMES Community-acquired acute pneumonia Streptococcus pneumoniae Mycoplasma pneumoniae Haemophilus influenzae Chlamydia spp. (C. pneumoniae, C. psittaci, C. trachomatis) Staphylococcus aureus Legionella pneumophila Viruses: RSV, parainfluenza virus (children); influenza (adults); adenovirus; SARS Nosocomial pneumonia Streptococcus pneumoniae Gram-negative bacilli Staphylococcus aureus Aspiration pneumonia Anaerobic oral flora (Bacteroides, Prevotella, Fusobacterium, Peptostreptococcus), admixed with aerobic bacteria (Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus influenzae, and Pseudomonas aeruginosa) Chronic pneumonia Mycobacterium tuberculosis and atypical mycobacteria Nocardia Actinomyces Necrotizing pneumonia and lung abscess Anaerobic bacteria (extremely common), with or without mixed aerobic infection Staphylococcus aureus, Klebsiella pneumoniae, Streptococcus pyogenes, and type 3 pneumococcus (uncommon) Pneumonia in the immunocompromised host Cytomegalovirus www.medicinemcq.com Page 8 of 14 Pneumocystis jerovicii Mycobacterium avium-intracellulare Invasive aspergillosis Invasive candidiasis "Usual" bacterial, viral, and fungal organisms (listed above) 7) What is the most common mechanism for the production of pneumonia? a. Aspiration b. Inhalation c. Hematogenous dissemination d. Direct inoculation Ans - A The major route of infection is microaspiration from a previously colonized oropharynx. Most pulmonary pathogens originate in the oropharyngeal flora. Aspiration of these pathogens is the most common mechanism for the production of pneumonia. The gingival crevices and dental plaques are sources of anaerobic pulmonary pathogens (e.g., Porphyromonas gingivalis, Prevotella melaninogenica, Fusobacterium nucleatum, Actinomyces spp., spirochetes, and anaerobic streptococci). Inhalation of suspended aerosolized microorganisms is the mechanism of infection for viruses, Legionella, and tuberculosis. www.medicinemcq.com Page 9 of 14 8) Aspiration of oropharyngeal secretions into the lower respiratory tract a. Common during sleep in healthy adults b. Common in those with an impaired level of consciousness c. Risk is increased in those with nasogastric tube d. All are true e. All are false Ans - D About 50% of healthy adults aspirate oropharyngeal secretions into the lower respiratory tract during sleep. Aspiration is more frequent in those with an impaired level of consciousness (e.g., alcoholics; drug abusers; and patients who have had seizures, strokes, or general anesthesia), neurologic dysfunction of the oropharynx, and swallowing disorders. Nasogastric or endotracheal tubes increase the risk. Nasogastric tubes can facilitate the transfer of gastric bacteria to the pharynx. 9) Gram-negative bacillary colonization of the oropharyngeal mucosa a. Is common in health b. Is due to decreased salivary proteolytic activity c. Is due to increase in fibronectin www.medicinemcq.com Page 10 of 14 d. All are true e. All are false Ans - E All are false statements. Aerobic gram-negative bacillary colonization of the oropharyngeal mucosa is unusual in healthy persons (<2%). Frequency increases with hospitalization, worsening debility, severe underlying illness, alcoholism, diabetes, and advanced age. This may be due to increased salivary proteolytic activity, which destroys fibronectin. Fibronectin is a glycoprotein coating the surface of the mucosa. Fibronectin is the receptor for the normal gram-positive flora of the oropharynx. Loss of fibronectin exposes the receptors for aerobic GNB on the epithelial cell surface. 10) Which pneumonia is typically not acquired by inhalation? a. Legionellosis b. Psittacosis c. Histoplasmosis d. Q fever e. Staphylococcus Ans - E www.medicinemcq.com Page 11 of 14 Pneumonia typically acquired by inhalation includes tuberculosis, influenza, legionellosis, psittacosis, histoplasmosis, Q fever, and Hantavirus pulmonary syndrome. Hematogenous dissemination from an extrapulmonary site is usually due to staphylococcus aureus. Hematogenous dissemination to the lungs occurs in IV drug users with bacterial endocarditis and in patients with IV catheter infections. Fusobacterium infections of the retropharyngeal tissues (Lemierre's syndrome - i.e., retropharyngeal abscess and jugular venous thrombophlebitis) also disseminate hematogenously to the lungs. 11) Lobar pneumonia is a. Involvement of an entire lobe b. Involvement of alveoli contiguous to bronchi c. Presence of cavities < 2 cm in diameter d. Presence of one or more cavities > 2 cm in diameter Ans - A The pneumonic process may involve primarily the interstitium or the alveoli. Involvement of an entire lobe is called lobar pneumonia. See figures below. When the process is restricted to alveoli contiguous to bronchi, it is called bronchopneumonia. Patchy consolidation of the lung is the dominant characteristic of bronchopneumonia. Confluent bronchopneumonia may be indistinguishable from lobar pneumonia. Cavities develop when necrotic lung tissue is discharged into communicating airways. This results in either necrotizing pneumonia or lung abscess. Necrotizing pneumonia is multiple small www.medicinemcq.com Page 12 of 14 cavities < 2 cm in diameter. Lung abscess is presence of one or more cavities > 2 cm in diameter. Lobar pneumonia www.medicinemcq.com Page 13 of 14 Bronchopneumonia 12) All are pathological stages of lobar pneumonia except a. Congestion b. Red hepatization c. Gray hepatization d. Resolution e. Pleurisy Ans - E The four stages of the inflammatory response in lobar pneumonia are congestion, red hepatization, gray hepatization, and resolution. In the first stage of congestion, there is vascular engorgement, intra-alveolar fluid with few neutrophils, and often numerous bacteria. www.medicinemcq.com Page 14 of 14 In red hepatization, the lobe is red, firm, and airless, with a liver-like consistency, hence the term hepatization. Red color is due to massive exudation of red cells. Neutrophils and fibrin also fill the alveolar spaces. In the stage of gray hepatization, there is progressive disintegration of red cells. The fibrinosuppurative exudate persists, giving the gross appearance of a grayish brown, dry surface. In the final stage of resolution, the exudate in the alveolar spaces undergoes enzymatic digestion. The product is semifluid, debris that is resorbed, ingested by macrophages, coughed up, or organized by fibroblasts growing into it. Lung tissue destruction and necrosis result in the formation of lung abscess. Pleuritis is often present in the early stages if the consolidation extends to the surface. Spread of infection to the pleural cavity causes empyema. www.medicinemcq.com