The Lower Respiratory Tract Bacterial · PDF fileThe Lower Respiratory Tract 10 T he lower...
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11 Common Clinical Conditions Common Clinical Conditions The Lower Respiratory Tract 10 T he lower respiratory tract (LRT) consists of the larynx (voice box), trachea (windpipe), bronchial tubes, and the alveoli. Due to the mucous membrane and filtering mechanisms of the bronchial tubes, the LRT normally contains few microbes. Therefore, if pathogens enter the LRT, serious respiratory disease may result. Several microbial diseases are associated with the LRT. Two of the bacterial diseases are pneumonia and tuberculosis, historically the two greatest infectious killers of humans. Infections of the LRT also exhibit themselves in several ways (see opposite page): Bronchitis: An inflammation of the bronchial lining (wall) by viruses or bacteria (Streptococcus, Mycoplasma, Chlamydia), producing a thick mucus that narrows the airways. Bronchiolitis: Usually restricted to young chil- dren, a viral infection of the bronchiole lining causes a swelling and narrowing of the airways, making expiration difficult (a wheezing sound heard). Pneumonia: An acute and complex syndrome resulting from an infection of the lung tissue and alveoli. Impaired gas exchange causes rapid and labored breathing, and cough. Bacterial Infections Bacterial diseases of the LRT are outlined below. Bacterial Pneumonias Pneumococcal pneumonia: Streptococcus pneumo- niae is responsible for about 80% of all pneumonia cases. It usually starts after an URT viral infection dam- ages the airways. Without appropriate antibiotic treat- ment, mortality is high, especially in the elderly. [FOM pp. 289–290] Primary atypical (walking) pneumonia: Caused by Mycoplasma pneumoniae, the infection is common in children and teenagers. The disease is rarely fatal. [FOM pp. 290–292] Legionellosis (Legionnaires’ disease): Legionella pneumophila is inhaled as aerosols from air-condition- ing devices or water supplies contaminated with the bacteria. After several days of incubation, symptoms appear with pneumonia being the most likely out- come. [FOM pp. 293–296] Q fever: This pneumonia-like infection, caused by Coxiella burnetii, is transmitted by inhaling aerosol droplets or consuming contaminated meat or unpas- teurized milk from infected animals. The mortality rate is low. [FOM pp. 296–297] Ornithosis (psittacosis): A rare pneumonia caused by the bacterium Chlamydia psittaci. The obligate intracellular bacteria are inhaled in dried droppings from infected birds (parrots, parakeets, pigeons, turkeys). Most cases are mild. [FOM pp. 298–299] Chlamydial pneumonia: Chlamydia pneumoniae also causes a form of pneumonia with symptoms and outcomes similar to primary atypical pneumonia. [FOM pp. 300–-301] Other Bacterial Diseases Pertussis (whooping cough): Caused by Bordetella pertussis, this highly contagious childhood disease pro- duces mucus in the respiratory system, which triggers coughing. Straining for air causes the “whooping” sound. [FOM pp. 279–280] Tuberculosis: An infection by Mycobacterium tuber- culosis, the major causative agent of tuberculosis (TB), starts by inhaling bacilli from an infected person. In the alveoli, the bacilli reproduce, leading to calcified aggre- gations of activated macrophages and lymphocytes (tubercles) surrounding the bacteria. [FOM pp. 284–288] Inhalation anthrax: Without treatment, this deadly disease begins with typical cold symptoms, but quickly leads to breathing difficulties and shock from toxins produced by the cells from the germinated Bacillus anthracis spores. [FOM pp. 344–346] Treatment Treatment Penicillin is the drug of choice for pneumococcal pneu- monia. Primary atypical and chlamydial pneumonia are treated with erythromycin or tetracycline. Legionellosis also can be treated with erythromycin. Q fever can be treated with doxycycline, while ornithosis is best treat- ed with tetracycline. TB treatment involves extended use of isoniazid and rifampin for 6 to 9 months. Pertussis can be treated with erythromycin and, if caught very early, inhalation anthrax is treatable with ciprofloxacin. Other Pneumonias Klebsiella pneumoniae and Serratia marcescens may produce pneumonias through a hospital-acquired infection. [FOM pp. 292–293] Pneumonia Bronchitis Bronchiolitis Trachea Alveoli False-colored chest X ray showing tuberculosis. The lungs contain lesions (pink) of infected tissue. (© Du Cane Medical Imaging, Ltd./Photo Researchers, Inc.) Syndromes associated with the LRT. Pneumococcal pneumo- nia: High fever, chest pain, persistent cough, rust-colored sputum; increased pulse, and difficulty breathing. Primary atypical and chlamydial pneumonia: Gradual and mild symptoms with fever, fatigue, and dry, hacking cough. Legionellosis: Pneumonia symptoms with fever, dry cough, diarrhea, and vomiting. Q fever: Dry cough, high fever, chest pain, and severe headache. Pertussis: Catarrhal stage: malaise, dry cough, fever; Paroxysmal stage: violent (whooping) cough; Convalescent stage: sporadic cough that slowly subsides. Ornithosis: Fever, headache, and dry cough. Tuberculosis: Fever, fatigue, weight loss, cough; shortness of breath and chest pain; tubercle development. Inhalation anthrax: Fever, chills, cough, chest pain, headache, malaise; severe breathing and shock result. Signs and Symptoms
Transcript of The Lower Respiratory Tract Bacterial · PDF fileThe Lower Respiratory Tract 10 T he lower...
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Common Clinical Conditions
Common Clinical Conditions
The Lower Respiratory Tract
10
The lower respiratory tract (LRT) consists of thelarynx (voice box), trachea (windpipe), bronchial
tubes, and the alveoli. Due to the mucous membraneand filtering mechanisms of the bronchial tubes, theLRT normally contains few microbes. Therefore, ifpathogens enter the LRT, serious respiratory diseasemay result.
Several microbial diseases are associated with the LRT.Two of the bacterial diseases are pneumonia andtuberculosis, historically the two greatest infectiouskillers of humans. Infections of the LRT also exhibitthemselves in several ways (see opposite page):
Bronchitis: An inflammation of the bronchiallining (wall) by viruses or bacteria
(Streptococcus, Mycoplasma, Chlamydia), producinga thick mucus that narrows the airways.
Bronchiolitis: Usually restricted to young chil-dren, a viral infection of the bronchiole liningcauses a swelling and narrowing of the airways,making expiration difficult (a wheezing soundheard).
Pneumonia: An acute and complex syndromeresulting from an infection of the lung tissue andalveoli. Impaired gas exchange causes rapid andlabored breathing, and cough.
Bacterial Infections Bacterial diseases of the LRT are outlined below.
Bacterial PneumoniasPneumococcal pneumonia: Streptococcus pneumo-niae is responsible for about 80% of all pneumoniacases. It usually starts after an URT viral infection dam-ages the airways. Without appropriate antibiotic treat-ment, mortality is high, especially in the elderly. [FOMpp. 289–290]
Primary atypical (walking) pneumonia: Caused byMycoplasma pneumoniae, the infection is common inchildren and teenagers. The disease is rarely fatal.[FOM pp. 290–292]
Legionellosis (Legionnaires’ disease): Legionellapneumophila is inhaled as aerosols from air-condition-ing devices or water supplies contaminated with thebacteria. After several days of incubation, symptomsappear with pneumonia being the most likely out-come. [FOM pp. 293–296]
Q fever: This pneumonia-like infection, caused byCoxiella burnetii, is transmitted by inhaling aerosoldroplets or consuming contaminated meat or unpas-teurized milk from infected animals. The mortality rateis low. [FOM pp. 296–297]
Ornithosis (psittacosis): A rare pneumonia causedby the bacterium Chlamydia psittaci. The obligateintracellular bacteria are inhaled in dried droppingsfrom infected birds (parrots, parakeets, pigeons,turkeys). Most cases are mild. [FOM pp. 298–299]
Chlamydial pneumonia: Chlamydia pneumoniaealso causes a form of pneumonia with symptoms andoutcomes similar to primary atypical pneumonia. [FOMpp. 300–-301]
Other Bacterial DiseasesPertussis (whooping cough): Caused by Bordetellapertussis, this highly contagious childhood disease pro-duces mucus in the respiratory system, which triggerscoughing. Straining for air causes the “whooping”sound. [FOM pp. 279–280]
Tuberculosis: An infection by Mycobacterium tuber-culosis, the major causative agent of tuberculosis (TB),starts by inhaling bacilli from an infected person. In thealveoli, the bacilli reproduce, leading to calcified aggre-gations of activated macrophages and lymphocytes(tubercles) surrounding the bacteria. [FOM pp.284–288]
Inhalation anthrax: Without treatment, this deadlydisease begins with typical cold symptoms, but quicklyleads to breathing difficulties and shock from toxinsproduced by the cells from the germinated Bacillusanthracis spores. [FOM pp. 344–346]
TreatmentTreatment
Penicillin is the drug of choice for pneumococcal pneu-monia. Primary atypical and chlamydial pneumonia aretreated with erythromycin or tetracycline. Legionellosisalso can be treated with erythromycin. Q fever can betreated with doxycycline, while ornithosis is best treat-ed with tetracycline.
TB treatment involves extended use of isoniazid andrifampin for 6 to 9 months. Pertussis can be treatedwith erythromycin and, if caught very early, inhalationanthrax is treatable with ciprofloxacin.
Other PneumoniasKlebsiella pneumoniae and Serratia marcescens may producepneumonias through a hospital-acquired infection. [FOM pp.292–293]
Pneumonia
Bronchitis
Bronchiolitis
Trachea
Alveoli
False-colored chest X ray showing tuberculosis. The lungs containlesions (pink) of infected tissue. (© Du Cane Medical Imaging,Ltd./Photo Researchers, Inc.)
Syndromes associated with the LRT.
Pneumococcal pneumo-nia: High fever, chest pain,persistent cough, rust-coloredsputum; increased pulse, anddifficulty breathing.
Primary atypical andchlamydial pneumonia:Gradual and mild symptomswith fever, fatigue, and dry,hacking cough. Legionellosis: Pneumonia
symptoms with fever, drycough, diarrhea, and vomiting.
Q fever: Dry cough, highfever, chest pain, and severeheadache.
Pertussis: Catarrhal stage:malaise, dry cough, fever;Paroxysmal stage: violent(whooping) cough;Convalescent stage: sporadiccough that slowly subsides.
Ornithosis: Fever, headache,and dry cough.
Tuberculosis: Fever, fatigue,weight loss, cough; shortnessof breath and chest pain;tubercle development.
Inhalation anthrax: Fever,chills, cough, chest pain,headache, malaise; severebreathing and shock result.
Signs and Symptoms
