Pathology and Microbiology of Lung Abscess
المؤلف:
Longo, D., Fauci, A. S., Kasper, D. L., Hauser, S., Jameson, J. L., Loscalzo, J., Holland, S. M., & Langford, C. A.
المصدر:
Harrisons Principles of Internal Medicine (2025)
الجزء والصفحة:
22e , p1035
2025-08-15
392
Primary Lung Abscesses The dependent segments (posterior upper lobes and superior lower lobes) are the most common locations of primary lung abscesses, given the predisposition of aspirated materials to be deposited in these areas. Generally, the right lung is affected more commonly than the left because the right mainstem bronchus is less angulated.
Primary lung abscesses often are polymicrobial, primarily including anaerobic organisms as well as microaerophilic streptococci (Table1). The retrieval and culture of anaerobes can be complicated by the contamination of samples with microbes from the oral cavity, the need for expeditious transport of the cultures to the laboratory, the need for early plating with special culture techniques, the prolonged time required for culture growth, and the need for collection of specimens prior to administration of antibiotics. When attention is paid to these factors, rates of recovery of specific isolates are reportedly as high as 78%.
Table1. Examples of Microbial Pathogens That Can Cause Lung Abscesses
Because it is not clear that knowing the identity of the causative anaerobic isolate alters the approach to treatment of a primary lung abscess, practice has shifted away from the use of specialized techniques to obtain material for culture, such as transtracheal aspiration and bronchoalveolar lavage with protected brush specimens that allow recovery of culture material while avoiding contamination from the oral cavity. When no pathogen is isolated from a primary lung abscess (which occurs as often as 40% of the time), the abscess is termed a nonspecific lung abscess, and the presence of anaerobes is often presumed. A putrid lung abscess refers to cases with foul-smelling breath, sputum, or empyema; these manifestations are essentially diagnostic of an anaerobic lung abscess.
Secondary Lung Abscesses The location of secondary abscesses may vary with the underlying cause. The microbiology of secondary lung abscesses can encompass a broad bacterial spectrum, with infection by Pseudomonas aeruginosa and other gram-negative rods the most common. In addition, a broad array of pathogens can be identified in patients from certain endemic areas and in specific clinical scenarios (e.g., a significant incidence of fungal infections among immunosuppressed patients following bone marrow or solid organ transplantation). Because immunocompromised hosts and patients without the classic presentation of a primary lung abscess can be infected with a wide array of unusual organisms (Table1), it is of special importance to obtain culture material to target therapy.
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