TOPICS
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Bronchiectasis
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Lung abscess
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Mycobacterial disease
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Tuberculosis
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Nontuberculous mycobacteria
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Swyer-James syndrome
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Pulmonary fungal infections
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Hydatid lung disease
Note : For all topics covered in this chapter, the focus will be on the possible roles of thoracic surgical interventions . For more detailed coverage of other aspects of each topic, the reader is referred to classic references and recent review articles cited.
BRONCHIECTASIS
Terminology
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Bronchiectasis
Definitions
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Abnormal permanent dilatation of airways, usually subsegmental airways.
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Multiple types of bronchiectasis
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Cylindrical –communicate with lung parenchyma, do not end blindly, with bronchi uniformly dilated
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Saccular/cystic –dilated bronchi ending in saccular structures. Can be as proximal as the 5th generation of bronchi, with more distal bronchi destroyed.
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Varicose –combination of saccular and cylindrical with beaded appearance
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Pseudobronchiectasis –can be seen acutely after pneumonia but resolves in weeks to months
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The above-mentioned types can be focal (i.e., localized to a segment or lobe) or diffuse .
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Etiology
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Infection
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Bacterial organisms: such as Pseudomonas aeruginosa, Haemophilus influenza, Escherichia coli, Klebsiella , and Staphylococcus aureus .
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Mycobacterium tuberculosis
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Nontuberculous mycobacteria: Mycobacterium. avium complex, Mycobacterium kansasii , or Mycobacterium abscessus
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Note: Allergic bronchopulmonary aspergillosis (ABPA) is due to an immune reaction to aspergillus, and is associated with proximal bronchiectasis and mucoid impaction.
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Viral infections (e.g., adenovirus, influenza, measles, and so on).
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Airway scarring/obstruction
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Extrinsic compression of bronchi (e.g., middle lobe syndrome due to compression by enlarged lymph nodes)
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Intrinsic bronchial obstruction (e.g., foreign body, tumor, and so on)
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Bronchial angulation after lobar resection
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Sequelae of toxic inhalation (e.g., chlorine)
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Congenital
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Cystic fibrosis–predilection for upper lobes
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Ciliary dyskinesia (e.g., Kartagener’s syndrome; primary ciliary dyskinesia; Young’s syndrome [secondary ciliary dyskinesia], and so on).
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Tracheobronchomegaly (Mounier Kuhn)
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Cartilage deficiency (Williams-Campbell)
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Alpha 1 antitrypsin deficiency
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Immune deficiency states/disorders predisposing to recurrent bacterial infection
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Hypogammaglobinemia: congenital or acquired. Includes specific immunoglogulin deficiencies, as well as subset deficiencies (for example, immunoglobulin G [IgG] subset deficiencies).
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Other rare disorders exhibiting combined humoral and cell-mediated immune deficiency states
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Chronic granulomatous disease; lazy leukocyte disorders; complement deficiency states
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Autoimmune disorders
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Rheumatoid arthritis, Sjögren’s syndrome, systemic lupus erythematosis
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Relapsing polychondritis
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Inflammatory bowel disease
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Miscellaneous
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Yellow nail syndrome (dystrophic nails, lymphedema, pleural effusions)
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Pathogenesis/Pathophysiology
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Bronchiectasis requires an infectious process plus impairment of bronchial drainage, airway obstruction, or a defect in host defenses. In cystic fibrosis, the process begins in the bronchioles.
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Causes of this combination include foreign body aspiration, external bronchial compression, ciliary dyskinesia, abnormal airway immune effector cells, excess neutrophils, proteases, and high levels of inflammatory cytokines
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Inflammation results in destruction of muscle, elastic tissue, and cartilage of the bronchial wall by infected mucopus within. Weakened bronchial walls become dilated and are also subject to traction forces.
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Bronchial arteries enlarge (up to 3 times normal), proliferate, and become tortuous to form an extensive network with anastomoses to the pulmonary circulation.
Clinical Features
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Clinical Presentation
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Recurrent pneumonia, chronic productive cough, foul-smelling sputum
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Symptoms persist for months to years despite antibiotic treatment.
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Nonproductive cough may be indicative of upper lobe involvement.
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Hemoptysis
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Owing to erosion of infectious process into hypertrophied bronchial circulation
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Less common in children than adults
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Typically affects basilar or dependent lung segments in most patients
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Preponderance for right middle lobe/lingular disease with nontuberculous mycobacterial (NTM) infection (Lady Windermere syndrome)
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Complications
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Recurrent infection
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Hemoptysis, occasionally massive in nature
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Progressive lung destruction (e.g. severe cystic bronchiectasis)
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Diagnostic Workup
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Full history, physical examination, and screen for underlying cause
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Patients commonly clubbed; auscultation reveals crackles, wheezes, or rhonchi in the majority of patients
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Full pulmonary function tests; screening blood work and quantitative immunoglobulins with IgG subsets.
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Sputum cultures typically grow mucoid P. aeruginosa, H. influenza , E. coli, Klebsiella , and early on in the course, S. aureus (as well documented in children with cystic fibrosis). In later stages, Burkholderia cepacia may complicate the microbiologic milieu, because several gemovars are highly resistant to antibiotic therapies.
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NTM, most commonly M. avium complex or M. abscessus , also frequently isolated
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Chest radiographs classically demonstrate evidence of thickened and dilated bronchi, as noted by the presence of ring shadows (seen on end) and tram tracks (seen longitudinally) ( Fig. 16-1 ).
Figure 16-1
Chest radiograph of a patient with cystic fibrosis, showing clear evidence of tram tracks (thickened parallel bronchial walls of dilated bronchus) especially in the right upper lobe, as well as ring shadows (cross-sectional equivalent of tram tracks). Relative sparing of the lung bases is evident.
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Sites of involvement: with cystic fibrosis, the lower zones are typically spared or less involved. In other causes of bronchiectasis, the most common sites of disease was reported as left lower lobe, right lower lobe, lingual, and right middle lobe. However, distribution depends on the etiologic factors causing bronchiectasis.
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Bronchography using contrast medium, once the standard for establishing the diagnosis of bronchiectasis, has been replaced by computed tomography ( Fig. 16-2 ).
Figure 16-2
Classic bronchogram depicting cystic bronchiectasis.
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High-resolution chest computed tomography (CT) is now the most common diagnostic tool with high accuracy. This clearly shows dilated bronchi, which also demonstrate ring shadows and tram tracks ( Fig. 16-3 ), diffuse or localized disease ( Fig. 16-4 ), or severe destruction and cystic bronchiectasis ( Fig. 16-5 ).
Figure 16-3
Computed tomography scan of the chest showing classic bronchiectasis (dilated bronchi exhibiting tram track and ring shadow appearance) in a bilateral diffuse manner.
Figure 16-4
Computed tomography scan of the chest showing classic localized bronchiectasis. A, Obvious “ring shadows” noted. B, Lower axial cut showing well demarcated “tram tracks.”
Figure 16-5
Computed tomography scan of the chest showing severe cystic bronchiectasis.
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Other tests depend on etiologic considerations (e.g., cystic fibrosis, dyskinetic cilia, and so on).
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Bronchoscopy can help localize a source of hemoptysis or provide secretion clearance in cases with significant atelectasis that are unresponsive to bronchial toilet and other measures.
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Treatment
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Medical
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Remains the mainstay of therapy
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Targeted antibiotic therapy–avoid excessive rounds of monotherapy, which tend to promote resistance
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Pulmonary toilet/hygiene is key feature of medical therapy
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Postural drainage
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Percussive therapy
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Flutter valves
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High frequency chest vibrators
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Humidification
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Mucolytics (e.g., DNAase of value in cystic fibrosis)
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Hypertonic saline inhalation (cystic fibrosis)
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Bronchodilators
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Surgical
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The rationale for surgery is to remove areas of permanently damaged lung parenchyma, into which the antibiotic therapy penetrates poorly. These areas have little impact on gas exchange, and serve as a reservoir to breed antibiotic resistance and seed later recurrence of the infection.
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Patients may benefit from resection when there is
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Localized symptomatic disease
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Failure of medical management
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Persistent and debilitating symptoms
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Multidrug resistance
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Drug intolerance
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Recurrent pneumonias
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Hemoptysis
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Localized, focal areas of bronchiectasis most amenable to resection
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“Debulking” of severe areas of lung destruction in setting of generalized disease may alleviate symptoms
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Resection may involve segmentectomy or lobectomy, or rarely pneumonectomy. Nonanatomic resections are less effective. Many resections are amenable to a thoracoscopic approach.
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Bronchial artery embolization may provide temporary relief of significant hemoptysis in setting of bronchiectasis. (See chapter 17 on Massive Hemoptysis.)
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With late-stage generalized bronchiectasis, bilateral lung transplantation may be considered. (See chapter 35 on Patient Selection for Lung Transplantation.)
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Principles of Peri- and Postoperative Management
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Optimization of medical therapy before surgery is important. Surgery alone is not advised or curative.
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Preoperative antimicrobial therapy is based on preoperative cultures and in vitro sensitivities when appropriate, and is extended for a few weeks (bacterial) to few months (mycobacterial) before surgery.
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Culture-negative sputum is preferable but not always possible in severe cases before surgery
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Antimicrobial therapy is continued through perioperative period; the extent of postoperative antimicrobial therapy is not well defined
Prevention and Management of Complications
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Use of double-lumen tubes and toilet bronchoscopy immediately before surgery for bronchiectasis is recommended.
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Avoidance of spillage within thoracic cavity and contact with chest wall/soft tissues, particularly in setting of certain mycobacterial infections such as M. abscessus
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An extrapleural dissection plane may be advantageous in the setting of significant pleural symphysis
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Active infection with positive sputum culture at the time of surgery may suggest the need for bronchial stump reinforcement with autologous tissue flap, most commonly transposed chest wall muscle or omentum, to minimize risk of bronchopleural fistula.
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An intrathoracic “space” is common after resectional surgery for infectious lung disease, will become smaller over time, and is not necessarily indicative of pneumothorax/parenchymal air leak.
Natural History/Prognosis
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Surgery is used as a therapeutic adjunct to remove permanently damaged areas of lung tissue that act as a reservoir for persistent organisms, leading to antibiotic resistance and recurrent infection.
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Usually chronic infection in the setting of impaired bronchial drainage.
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Dependent areas, as well as right middle lobe/lingular, are commonly involved.
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Surgical resection used in select cases as an adjunct to medical therapy.
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Culture negative sputum is preferable before surgery but not always possible.
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“Debulking” of most severe areas is occasionally helpful for symptom relief and to prevent progressive lung destruction of uninvolved areas.
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Buttressing of bronchial stump is recommended for major resection (particularly pneumonectomy) in the setting of active infection.
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A 47-year-old woman with 12-year history of recurrent pulmonary infections, consisting of productive cough, fever, and occasional scant hemoptysis. Has been placed on a rotating antibiotic therapy course for suppression. Previous cultures have grown P. aeruginosa
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She now describes a several-month history of productive cough, malaise, and 10 lb. weight loss. Workup including chest CT ( Fig. 16-6 ) demonstrates focal bronchiectasis involving the right middle lobe and lingula. Bronchoscopy with BAL demonstrate Mycobacterium avium complex (MAC). In vitro susceptibility testing demonstrates no macrolide resistance.
Figure 16-6
Computed tomography scan of the chest of patient in first illustrative case, depicting focal bronchiectasis involving the right middle lobe and lingula.
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She is placed on a four-drug regimen (azithromycin, rifampin, ethambutol, and IV amikacin). At 12 weeks after initiation of therapy, she undergoes thoracoscopic right middle lobectomy, with continuing antibiotic coverage. Testing of tissue obtained at operation show no AFB (MAC) by smear or culture.
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With continuing antibiotic coverage, 6 weeks later, she has thoracoscopic lingulectomy. Pathologic specimens remain smear and culture negative. The IV antibiotics are discontinued, and the oral regimen is continued for another nine months.
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Subsequent testing by sputum culture and radiologic imaging demonstrate no recurrence of MAC or recurrent parenchymal disease at 4 years from termination of therapy
LUNG ABSCESS
Terminology
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Abscess within the lung parenchyma
Definition
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Abscess cavity in the lung parenchyma secondary to localized suppuration with parenchymal destruction. Central necrosis tends to liquefy and communicate with the bronchial tree. Communication with the airway leads to classic air-fluid level seen on radiologic studies
Etiology
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Aspiration
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Predilection for dependent areas, that is, the posterior segment of the right upper lobe (RUL), the superior segments of both lower lobes and other lower lobe segments.
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May occur in setting of impaired consciousness, alcoholism, gastroesophageal reflux disease, other dysphagia syndromes (stricture, Zenker’s diverticulum, and so on). Poor dental hygiene, gingival disease, and high bacterial counts in gingival crevices are common.
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Bacteriology: anaerobes (most common) and aerobes (e.g., Streptococcus. milleri ); commonly mixed anaerobe and aerobic flora. The environment in which aspiration occurs also impacts. For example hospital or nursing home flora colonization.
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Endobronchial obstruction: neoplasms, foreign bodies, and external bronchial compression can result in distal infection and abscess formation
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Following necrotizing lung infection
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Bacteriology: Staphylococcus, Streptococcus, Klebsiella, other gram-negative organisms, Legionella, Actinomyces.
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More prevalent in the immunocompromised host. In the setting of cell-mediated immune dysfunction, consider bacterial organisms as above, Nocardia, Rhodococcus, mycobacterial, fungal and parasitic
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Secondary infection of pre-existing lung cavity (emphysema, resolving infarct, cavitating neoplasm)
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Hematogenous seeding of lung parenchyma, often multifocal
Clinical Features
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Clinical Presentation
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Fever, chills, severe cough, hemoptysis, and copious, foul-smelling sputum
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Leukocytosis with left shift
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Tachypnea, consolidation, local chest wall tenderness
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Hemoptysis occurs rarely
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Contributing factors can include, but are not limited to, suboptimal dental hygiene, alcohol abuse, seizure disorders, immunosuppression, neuromuscular disorders with bulbar dysfunction, esophageal dysmotility, bronchial obstruction.
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Complications
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Bronchopleural fistula and/or empyema can develop if abscess communicates with the pleural space.
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Systemic infection/sepsis
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Diagnostic Workup
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Chest radiograph: pneumonitis pattern appears early, followed by air/fluid level once airway has been invaded/eroded
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Chest CT delineates the exact anatomic features and location of the abscess and its relation to adjacent structures
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Culture: aerobic, anaerobic, fungal, acid-fast bacteria can play role
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Can direct therapy based on culture growth
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Percutaneous sampling often yields best results
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Bronchoscopy is indicated to rule out obstructing foreign bodies or neoplasm.
Treatment
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Medical
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Most abscesses respond to appropriate medical treatment.
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Empiric antibiotic therapy often used until cultures define pathogen.
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Duration of antibiotic therapy in typical bacterial lung abscess is controversial. The duration is commonly at least 4 to 6 weeks and most often longer (months) depending on pathogen, clinical response, and if there is substantial radiologic improvement
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Drainage of the cavity may be possible with aggressive chest physiotherapy, postural drainage
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Bronchoscopic and percutaneous drainage, in addition to appropriate antimicrobial therapy, have also been used in certain circumstances.
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The complications of percutaneous drainage (empyema, pneumothorax, hemothorax) occur in less than 10% of cases.
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Surgery
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Indications include
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Failure of medical therapy
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Significant hemoptysis
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Empyema secondary to abscess erosion into pleura space
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Suspicion of underlying malignancy
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Most commonly involves anatomic resection, usually lobectomy
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In cases of abscess perforation into pleural space, simple unroofing of abscess, decortication, and wide drainage usually suffice
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Special measures should be taken during surgery to avoid endobronchial spillage into contralateral lung
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Pulmonary gangrene
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Definition: severe lung infection with extensive devitalization of lung tissue and necrosis. Often is secondarily infected.
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Surgery in such conditions is controversial. Failure of medical therapy and ongoing sepsis is a consideration
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A case series of 35 cases reported an 8.5% postoperative mortality. Lobectomy was most commonly performed.
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Surgical complications could include bronchopleural fistula, empyema, and mediastinitis.
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Reinforcement of the bronchial stump is advised.
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Principles of Peri- and Postoperative Management
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Obtain good cultures and allow them to direct antimicrobial therapy
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Address underlying cause of abscess
Prevention and Management of Complications
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Broad-spectrum antibiotics until cultures identify specific pathogen
Natural History/Prognosis
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Good prognosis once drained and treated with antibiotics.
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Antibiotic duration may last for 6 to 8 weeks
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Radiologic resolution may take 4 to 5 months
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Identify predisposition–chronic aspiration, airway obstruction, and so on that could lead to recurrence
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Medical therapy depends on adequate drainage and appropriate antibiotic selection.
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Surgery mainly reserved for failure of medical therapy and complications of primary condition.
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Underlying cause of abscess must be addressed to minimize recurrence.
TUBERCULOSIS
Terminology
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Tuberculosis (TB)
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Multidrug resistant tuberculosis (MDR-TB)
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Extensive drug resistant tuberculosis (XDR-TB)
Definition
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Variety of infections caused by Mycobacterium tuberculosis , most commonly pulmonary. Other organ systems are occasionally involved.
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MDR-TB is resistant to at least isoniazid and rifampin
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Extensive (extremely) drug-resistant tuberculosis (XDR-TB) is resistant to at least isoniazid, rifampin, fluoroquinolones, and either aminoglycosides, capreomycin, or both.
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Primary resistance occurs in patients never before treated
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Secondary resistance is the development of resistance in a previously susceptible strain during or after treatment
Etiology
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Mycobacterium tuberculosis
Pathogenesis/Pathophysiology
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Most commonly begins with pulmonary transmission with inhalation of droplet nuclei (5 to 10 μ), which are deposited in the lung midzones on either side to produce the Ghon focus. Spread to regional lymph nodes produces the Ghon complex (primary TB), which is contained by the development of cell mediated immunity over 2 to 6 weeks.
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With the initial innoculum, if innate immunity fails to contain (before the development of full cell-mediated immunity), the organisms will continue to proliferate and a few organisms may seed and then remain dormant in several organs (i.e., apices of the lung; kidneys, bones, and so on).
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Failure to contain the primary infection results in continued proliferation and invasion of blood vessels and lymphatics to produce generalized miliary dissemination, erosion into a bronchus to produce a bronchopneumonic process, and so on.
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Reactivation TB occurs when latent bacilli start to proliferate, often many years later. The exact mechanisms that maintain a dormant state and reactivation are not fully understood, but impairment of cell-mediated immunity under different circumstances plays a role. Figure 16-7 shows a chest radiograph of reactivation TB in the right upper lobe.
Figure 16-7
Chest radiograph of a patient with reactivation tuberculosis. Extensive cavitary disease is noted in the right upper lobe.
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In general, with exposure and infection, about 3% to 5% of patients develop clinical disease within 1 year, with a 3% to 5% lifetime chance of late disease thereafter.
Clinical Features
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Demographic
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There were an estimated 9.2 million cases of TB worldwide in 2006
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Approximately 5% of cases MDR-TB.
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About 12,000 cases of TB were reported in the United States during same time period.
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Clinical presentation
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Night sweats, fever, cough, and occasionally hemoptysis
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See classic texts and papers for more details, such as references and .
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Complications
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A cause of severe hemoptysis (see chapter 17 on Massive Hemoptysis)
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See classic texts and papers for more details, such as references .
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Diagnostic Workup
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Diagnosis is confirmed with acid-fast staining and culture of the sputum or other fluids/tissue sources
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Susceptibility to first- and second-line agents should be tested
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See classic texts and papers for more details, such as references .
Treatment
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Medical
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First-line therapy: isoniazid, ethambutol, pyrazinamide, and rifampin.
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The (current) preferred regimen is isoniazid and rifampin for 6 months, with ethambutol and pyrazinamide administered for the first 2 months.
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If the sputum is positive after 3 months of treatment, either the patient is noncompliant, the organism is resistant, or the diagnosis is incorrect; the patient should be recultured
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Never add a single drug to a failing regimen
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Pure tuberculous effusions almost always resolve spontaneously or respond promptly to chemotherapy
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Tube thoracostomy rarely provides a cure because dense pleural reaction interferes with full re-expansion of the underlying lung
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MDR-TB regimens should include at least four drugs (usually five or more), ranging from 18 to 24 months of treatment.
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Regimen can be dictated by a specific pattern of resistance.
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Most commonly an aminoglycoside and a fluoroquinolone are used for this situation, among others. These regimens need to be given with direct observation of the patients for effectiveness and side effects, which can be common
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With fluoroquinolones, take 2 hours after meals to optimize absorption
- •
Consider drug levels at 2 and 6 hours postingestion when delayed absorption or malabsorption is suspect. Low levels can also induce resistance
- •
- ○
XDR-TB use all first-line agents to which there is susceptibility and at least two second-line agents for a minimum of four to five drugs.
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See American Thoracic Society statement on hepatotoxity of antituberculous therapy.
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Surgical
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Indications for surgical resection
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Localized resistant TB
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Persistent cavitary disease after extended treatment with ≥2 drugs
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Continued positive sputum
- •
MDR-TB or XDR-TB with destroyed lobe or lung
- •
Massive (>600 mL/24 hours) or recurrent severe (>200 mL/24 hours) hemoptysis
- •
Bronchopleural fistula
- •
Bronchial stenosis secondary to endobronchial TB
- •
- ○
Contraindications to resection
- •
Widespread, diffuse pulmonary parenchymal involvement
- •
Inadequate pulmonary reserve
- •
Active endobronchial disease, because this interferes with healing of bronchial stump (preoperative bronchoscopy in all patients before resection)
- •
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Surgical Goals
- •
Surgery remains adjunct to medical therapy, which remains primary treatment modality
- •
Obliterate cavities, excise damaged lung
- •
Lobectomy or pneumonectomy necessary with active disease
- •
Extrapleural pneumonectomy required in cases of extensive pulmonary parenchymal disease and chronic empyema
- •
- ○
Surgical outcomes in drug-resistant TB
- •
A retrospective analysis of 205 patients treated for MDR-TB reported long-term success rates of 75%. Surgical resection and the use of fluoroquinolones was associated with improved outcomes.
- •
In a recent report of surgery in 121 patients for drug-resistant TB who had failed medical therapy with a median of seven drugs, sustained culture-free status among survivors was 74.8%. Postoperative complications were noted in 22.6% of patients.
- •
Other reports of surgery for MDR-TB similarly show improved outcome and low relapse rates.
- •
- ○
Principles of Peri- and Postoperative Management
- ▪
Continue multidrug therapy until sputum clear (usually 6 to 9 months)
- ▪
Nutritional supplementation is very important because malnutrition is rampant in this population
Prevention and Management of Complications
- ▪
Complications include empyema, bronchopleural fistula, and bronchogenic spread of mycobacterial disease.
- ○
These are more frequent when the sputum is positive at the time of operation.
- ○
Some believe that eradication of the disease requires obliteration of all space with latissimus or pectoralis free flap, or with thoracoplasty to reduce residual pleural space.
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- ▪
Prevention: complications may be limited but not completely avoided in these patients with buttressing of the divided airway with tissue flap.
- ○
Omental or muscle flaps are most common.
- ○
Natural History/Prognosis
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Progression common
- ▪
Resistance organisms are important and significant public health issue
- ▪
A recent study of 48 patients with XDR-TB treated with aggressive appropriate therapy reported a 60% cure rate, with the cure rate for 603 patients with MDR-TB reported as 66%. Thoracic surgical procedures were performed in five out of 28 patients with XDR-TB after a median of 31 months of chemotherapy and in 87 out of 603 patients with MDR-TB.
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Delivery of therapy remains major stumbling block to effective eradication of infection.
- ▪
Indications for surgery much more common with MDR-TB and XDR-TB.
- ▪
Know local patterns of resistance (or where the patient contracted the infection).
- •
A 22-year-old woman who emigrated from the far east presents with fever, night sweats, and productive cough of several months duration.
- •
Skin PPD is positive.
- •
Chest CT is performed ( Fig. 16-8 ), demonstrating severe bronchiectatic and cavitary parenchymal disease involving the right lung. The majority of the right lung is essentially destroyed. The left lung is relatively free of damage
Figure 16-8
A chest computed tomography scan of the patient in second illustrative case, demonstrating severe bronchiectatic and cavitary parenchymal disease involving the right lung. The majority of the right lung is essentially destroyed. A hydropneumothorax is evident. The left lung is relatively free of damage.
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Induced sputum and BAL yield a positive AFB smear; TB resistant to isoniazid and rifampin is isolated
- •
Treatment is initiated with IV amikacin, ethambutol, pyrazinamide, and moxifloxacin.
- •
At 6 months, the patient is clinically improved but still AFB positive on sputum smear. Workup is undertaken for right pneumonectomy. Adequate pulmonary reserve is demonstrated
- •
A right pneumonectomy is performed using an extrapleural approach. The right main stem bronchial stump is covered with intercostal muscle flap. The postoperative course is uneventful. Conversion to smear and culture negative status was confirmed.
- •
Antibiotics are continued for another 18 months, with no recurrence of symptoms.
NONTUBERCULOUS MYCOBACTERIAL INFECTIONS
Terminology
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Also known as atypical mycobacteria, mycobacteria other than tuberculosis (MOTT), environmental mycobacteria
- ▪
See monograph on NTM infections.
Definition
- ▪
A spectrum of pulmonary infections with mycobacteria other than M. tuberculosis
Etiology
- ▪
NTM organisms are ubiquitous in the environment
- ○
Found in water, soils, food, and on surfaces
- ○
Resistant to chlorination, disinfectants
- ○
Not obligate pathogens
- ○
- ▪
Increased incidence of infection in Gulf Coast states, but infection can be seen in all states.
- ▪
Cause of increased susceptibility in some individuals is unclear but likely genetic in nature.
- ▪
No person-to-person transmission.
- ▪
Actual incidence is unknown but appears to be on the rise.
Pathogenesis/Pathophysiology
- ▪
Risk factors for pulmonary infection
- ○
Geographic location (Gulf Coast)
- ○
Occupational exposure to soils (possibly water)
- ○
Pre-existing lung disease
- ○
Chronic obstructive pulmonary disease (COPD)
- ○
Gastroesophageal reflux
- ○
Cavitary disease
- ○
Bronchiectasis
- ○
Cystic Fibrosis
- ○
Female gender
- ○
Interferon gamma pathway defects
- ○
Scoliosis, pectus excavatum
- ○
- ▪
Transmission is not from person to person.
- ▪
Main NTM pathogens include
- ○
Slow-growing organisms
- •
MAC
- ○
M. avium
- ○
M. intracellulare
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M. xenopi, M. malmonense, M. simiae, M. kansasii
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Rapid-growing organisms, so named because of their rapid isolation in vitro
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M. abscessus
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M. chelonae
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M. fortuitum
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Clinical Features
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Demographic
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Not communicable, and thus true incidence not tracked by the Centers for Disease Control and Prevention.
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May be associated with COPD, pulmonary fibrosis, and rheumatoid arthritis.
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Rising incidence of certain phenotypes, such as middle-aged, slender white women.
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Clinical Presentation
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Chronic productive cough, dyspnea, hemoptysis, fatigue, recurrent pneumonias, fever
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Two main clinical presentations
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Middle-aged or elderly men, often with history of smoking and underlying COPD. Resembles TB with upper lobe cavitary disease. May progress to complete lung destruction.
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Women older than 50 years of age, thin, white, nonsmokers, with right middle lobe and lingular disease—typically fibronodular bronchiectasis with occasional consolidation or cavity formation.
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Complications
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Chronic infection can lead to significant lung destruction and nonfunctional parenchyma
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Lung destruction may progress to other areas not initially involved with infection
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Cachexia and malnutrition
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Hemoptysis, rarely massive
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Diagnostic Workup
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Distinction between colonization, contamination, and true infection can be difficult
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Culture testing
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Cultures placed on both solid and liquid media.
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Growth can take 4 to 6 weeks.
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Liquid media is faster (10 to 14 days) but less sensitive.
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Rapid growers may take less than 1 week in culture.
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Decontamination required to prevent bacterial overgrowth.
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Tissue specimens “double cultured.”
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Nucleic probes used to identify precise organism
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Routine sensitivity testing discouraged.
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MAC: macrolide testing.
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M. kansasii: rifampin testing
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Radiologic studies demonstrate typical patterns of disease
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Fibronodular bronchiectasis
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Cavitary lung disease
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Destroyed lung
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Diagnosis usually requires presence of symptoms, characteristic radiologic findings, and repeated (two to three) positive cultures/smears after malignancy, TB, and fungal disease excluded
Treatment
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Medical 60.61
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Primarily involves multidrug antibiotic therapy, often for 18 months
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Therapy directed in part by susceptibility testing, and should be continued 12 months after culture negative
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Examples include
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MAC: macrolide, rifampin, ethambutol, with or without amikacin
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M. kansasii : rifampin, ethambutol, isoniazid
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M. abscessus : macrolide, amikacin, cefoxitin, and imipenem. The regimen for combination therapy is ultimately based on sensitivities to include several of these agents.
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Multidrug combination therapy can be difficult to take, and therefore, compliance with medical therapy can be poor
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Surgical
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Rationale for surgery is to remove areas of devitalized lung tissue that do not “see” the delivered antibiotic therapy, and thus serve as a reservoir for the offending organism, promoting recurrence of the infection at a later date
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Indications for surgery similar to those for bronchiectasis—persistent, focal (cavitary or bronchiectatic) parenchymal disease after recurrent antimicrobial treatment
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Occasionally, “debulking” procedures in setting of nonfocal disease may slow disease progression and reduce symptoms
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Pretreatment with targeted antimicrobial therapy for at least 2 to 3 months is essential before surgical intervention.
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Anatomic lung resection (segment, lobe) is preferable.
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Thoracoscopic approach is possible in many cases; bilateral thoracoscopic resections are usually staged 6 to 8 weeks apart
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In cases of significant pleural symphysis, extrapleural dissection may be needed.
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Severe disease may require pneumonectomy
Principles of Peri- and Postoperative Management
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Nutrition is key to good outcomes
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Antibiotics continue throughout perioperative course. Culture results from surgical specimens guide further antibiotic management. Medical therapy often continued for many months after surgery
Prevention and Management of Complications
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Morbidity and mortality of these procedures is generally low
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Common misconceptions/mistakes include
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Inadequate pretreatment with targeted antimicrobial therapy
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Lack of focal disease
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Nonanatomic or incomplete resection
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Expect an intrathoracic space after anatomic resection
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Buttress pneumonectomy stumps or in setting of poorly controlled infection
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Create an open thoracostomy if pleural contamination occurs
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Bronchopleural fistula most serious complication, associated with
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MAC infection
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Right pneumonectomy
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Positive sputum at operation
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Certain rapid growers, such as M. abscessus , can cause troublesome skin and soft tissue infections
Natural History/Prognosis
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Long-term surgical outcomes remain unknown
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Treatment goal is suppression or remission, not cure, because determinants of susceptibility remain unknown
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Environmental organisms without person-to-person transmission
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Diagnosis can be difficult to establish
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Prolonged multidrug antibiotic regimen is mainstay of therapy
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Surgery used in select cases of focal, recurrent disease
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