Vol.68 No.3 May 2020
Refractory respiratory infections in clinical practice
Department of Pulmonology, Kameda Medical Center, 929 Higashi-cho, Kamogawa, Chiba, Japan
Abstract
There is no standard definition for refractory respiratory tract infections. However, in view of the fact that antimicrobial drugs are the mainstay of treatment, it could be defined as infections that are difficult to control by antibiotic treatment alone. Factors related to refractoriness could be divided into host-related factors, pathogen-related factors and therapy-related factors.
1. Host-related factors
Since the focus of infection resides in the respiratory tract, lung or pleural space, structural destruction of the lung parenchyma or bronchi associated with cysts, cavities, bronchiectasis, lung abscesses and pleural fluid collection may cause poor distribution of antimicrobial drugs to these lesions. Such patients would require additional physical therapy such as drainage and/or surgical resection. In immunocompromised hosts, the range of pathogens that can cause disease is significantly broader. In such cases, chest imaging findings may provide a clue for identifying the infecting pathogens, however comprehensive laboratory testing and empiric broad-spectrum treatments are sometimes required. In patients with hematological disorders presenting with invasive pulmonary mycoses infections, invasive procedures for obtaining lung specimens for diagnostic tests are often difficult to perform due to the hemorrhagic diathesis.
2. Pathogen-related factors
In addition to emergence of drug-resistant organisms, there are also many microorganisms for which no established standard medical therapies exist. Sometimes, different results from two or more methods for drug susceptibility testing might make the selection of therapeutic agents difficult. Because filamentous fungi are sometimes difficult to identify by microbiological methods, morphological diagnosis based on examination of tissue specimens is needed.
3. Therapy-related factors
Some respiratory infections, such as chronic progressive pulmonary aspergillosis or Mycobacterium abscessus infection, require long-term antibiotic treatment, even though the optimal durations of treatment still remain to be established.
4. Lesions that occur secondary to infection
Sometimes secondary lesions, such as infectious aneurysms and bronchopleural fistula develop secondary to infection, and specific treatments other than antibiotic therapy, may be required, making the condition more difficult to control.
In this review, I present some examples of refractory respiratory tract infections that I have encountered, with a description of the cases from the viewpoints of the factors listed above, and propose multidisciplinary treatment, including surgery and/or bronchoscopic and intravascular interventions, as one of the solutions for overcoming refractory respiratory infections.
Key word
interventional radiology, lung abscess, non-tuberculous mycobacteriosis, surgical procedure, thoracic empyema
Received
January 9, 2019
Accepted
January 27, 2020
Jpn. J. Chemother. 68 (3): 345-359, 2020
