Mycobacterium abscessus is the second most important pathogen in pulmonary disease caused by nontuberculous mycobacteria (NTM), following Mycobacterium avium. Mycobacterium abscessus is classified into three subspecies: M. abscessus subsp. abscessus, M. abscessus subsp. massiliense, and M. abscessus subsp. bolletii. Mycobacterium abscessus is the most difficult to treat NTM due to its resistance to many antibiotics. Treatment should include an initial regimen of 2–3 injectable and oral antibiotics for several weeks or months, followed by inhaled amikacin and 1–3 oral antibiotics, depending on the subspecies and drug susceptibility patterns, including macrolide susceptibility. The continuation phase should be continued for a minimum of 12 months after culture conversion. Suitable injectable antibiotics include amikacin, imipenem, cefoxitin, and tigecycline, while oral antibiotics include macrolides (azithromycin or clarithromycin), clofazimine, linezolid, and moxifloxacin. Surgery can be a useful adjunctive therapy for some patients with refractory disease. However, the overall treatment prognosis is still unsatisfactory. Therefore, novel and more effective interventions are required for the treatment of M. abscessus pulmonary disease.
Amikacin ; Anti-Bacterial Agents ; Cefoxitin ; Clofazimine ; Humans ; Imipenem ; Linezolid ; Lung Diseases ; Macrolides ; Mycobacterium avium ; Mycobacterium ; Nontuberculous Mycobacteria ; Prognosis

Mycobacterium abscessus is the second most important pathogen in pulmonary disease caused by nontuberculous mycobacteria (NTM), following Mycobacterium avium. Mycobacterium abscessus is classified into three subspecies: M. abscessus subsp. abscessus, M. abscessus subsp. massiliense, and M. abscessus subsp. bolletii. Mycobacterium abscessus is the most difficult to treat NTM due to its resistance to many antibiotics. Treatment should include an initial regimen of 2–3 injectable and oral antibiotics for several weeks or months, followed by inhaled amikacin and 1–3 oral antibiotics, depending on the subspecies and drug susceptibility patterns, including macrolide susceptibility. The continuation phase should be continued for a minimum of 12 months after culture conversion. Suitable injectable antibiotics include amikacin, imipenem, cefoxitin, and tigecycline, while oral antibiotics include macrolides (azithromycin or clarithromycin), clofazimine, linezolid, and moxifloxacin. Surgery can be a useful adjunctive therapy for some patients with refractory disease. However, the overall treatment prognosis is still unsatisfactory. Therefore, novel and more effective interventions are required for the treatment of M. abscessus pulmonary disease.

Nontuberculous mycobacteria are mycobacteria other than those that cause tuberculosis and leprosy and can cause infections in various parts of the body, predominantly the lungs. Of approximately 200 species of nontuberculous mycobacteria, only about 10 are linked to pulmonary infections, with Mycobacterium avium complex (MAC) being the most common.Current Concepts: The standard treatment for pulmonary diseases caused by the MAC is combination therapy, including macrolide antibiotics and other antibiotics such as ethambutol and rifampin. Among macrolide antibiotics, azithromycin and clarithromycin are commonly used for managing MAC pulmonary diseases, and in cases with extensive lesions, amikacin injections are administered concurrently during the initial stages of treatment. Ensuring an overall treatment duration of an additional 12 months after negative culture conversion is recommended in affected patients. However, despite an extended treatment period, the cure rate remains at 60~70%. Recently, an inhalable liposomal form of amikacin, marketed as ARIKAYCE, has been developed. It has been approved by the US Food and Drug Administration as an effective treatment for refractory MAC pulmonary diseases. When ARIKAYCE was used for an additional 6 months or more in patients with refractory MAC pulmonary diseases, approximately 29% of patients achieved additional treatment success. However, it has yet to be officially imported into South Korea, and a high monthly cost restricts its practical use in the country. Therefore, the treatment of MAC pulmonary disease in South Korea will remain a challenge, unless a more effective treatment emerges.Discussion and Conclusion: MAC pulmonary disease requires long-term combination antibiotic therapy, usually with macrolides, ethambutol, and rifampin, and amikacin injections are recommended for cases with extensive lesions. The lack of effective drugs hampers treatment, increasing the burden of antibiotic side effects. Therefore, more research is urgently needed for better treatment of MAC pulmonary disease.

Adenovirus (AdV) can cause severe pneumonia in non-immunocompromised host, but limited data exist on the distinctive characteristics of AdV pneumonia in non-immunocompromised patients. We evaluated distinctive clinico-laboratory and radiological characteristics and outcomes of AdV pneumonia (n = 179), compared with non-AdV pneumonia (n = 188) in Korean military personnel between 2012 and 2016. AdV pneumonia patients had a higher rate of consolidation with ground-glass opacity (101/152) in lobar distribution (89/152) on computed tomography (CT) (P < 0.001). Laboratory findings showed a higher incidence of unusual blood profiles such as leukopenia (55/179, P < 0.001) or thrombocytopenia (100/179, P < 0.001). The patients had more systemic symptoms such as myalgia (82/179, P = 0.001) or diarrhea (23/179, P < 0.001), compared with non-AdV pneumonia patients. Bacterial co-infection was identified in 28.5% of AdV pneumonia. Most of the AdV isolates typed (69/72, 95.8%) were AdV-55. Patients with a pneumonia severity index ≥ class III were more commonly observed in AdV pneumonia patients compared with non-AdV pneumonia patients (11.2% vs. 2.1%, P < 0.001), and time to clinical stabilization from admission was longer in the AdV pneumonia patients compared with the non-AdV pneumonia patients (3.8 vs. 2.6 days, P < 0.001). Mechanical ventilation (n = 6) was only required in AdV pneumonia patients, one of whom died due to AdV-55. Our data showed that AdV pneumonia in non-immunocompromised patients had distinct characteristics and most of the isolates typed in our study were AdV-55. It is suggested that AdV-55 is an important pathogen of pneumonia in Korean military personnel.
Adenoviridae* ; Coinfection ; Diarrhea ; Humans ; Incidence ; Leukopenia ; Military Personnel* ; Myalgia ; Pneumonia* ; Respiration, Artificial ; Thrombocytopenia

Acute eosinophilic pneumonia (AEP) is an uncommon inflammatory lung disease, and limited data exist concerning the clinical characteristics and factors that influence its occurrence. We retrospectively reviewed the records of AEP patients treated at Korean military hospitals between January 2007 and December 2013. In total, 333 patients were identified; their median age was 22 years, and all were men. All patients presented with acute respiratory symptoms (cough, sputum, dyspnea, or fever) and had elevated levels of inflammatory markers including median values of 13,185/microL for white blood cell count and 9.51 mg/dL for C-reactive protein. All patients showed diffuse ground glass opacity/consolidation, and most had pleural effusion (n = 265; 80%) or interlobular septal thickening (n = 265; 85%) on chest computed tomography. Most patients had normal body mass index (n = 255; 77%), and only 30 (9%) patients had underlying diseases including rhinitis, asthma, or atopic dermatitis. Most patients had recently changed smoking habits (n = 288; 87%) and were Army personnel (n = 297; 89%).The AEP incidence was higher in the Army group compared to the Navy or Air Force group for every year (P = 0.002). Both the number of patients and patients with high illness severity (oxygen requirement, intensive care unit admission, and pneumonia severity score class > or = III) tended to increase as seasonal temperatures rose. We describe the clinical characteristics of AEP and demonstrate that AEP patients have recently changed smoking habits and work for the Army. There is an increasing tendency in the numbers of patients and those with higher AEP severity with rising seasonal temperatures.
Acute Disease ; Asian Continental Ancestry Group ; C-Reactive Protein/analysis ; Cough/etiology ; Dyspnea/etiology ; Fever/etiology ; Humans ; Incidence ; Leukocyte Count ; Male ; Military Personnel ; Pleural Effusion/complications/diagnosis/radiography ; Pulmonary Eosinophilia/complications/*diagnosis/pathology ; Republic of Korea/epidemiology ; Retrospective Studies ; Seasons ; Severity of Illness Index ; Smoking ; Tomography, X-Ray Computed ; Young Adult

The incidence and prevalence of pulmonary tuberculosis (TB) in South Korea remain high despite the fact that South Korea is a high-income country, and pulmonary TB is an important public health issue in terms of both morbidity and mortality. Thus, rapid diagnosis and management of active pulmonary TB are crucial for effective TB control, which can help to prevent the transmission of TB and the occurrence of new TB cases. However, because the clinical and radiological presentations of pulmonary TB may occasionally be nonspecific, identification of causative microorganisms using laboratory tests is the most important diagnostic method. Recently-developed microbiological and molecular techniques are commonly employed in current clinical practice. In particular, advances in liquid culture system, line probe assays, and Xpert MTB/RIF assay have reduced the identification time and facilitate the identification of drug-resistance TB. However, as various tests have both advantages and limitations, physicians should be aware of the principles underpinning the tests when interpreting the results. Thus, the clinical and radiological characteristics of pulmonary TB and several diagnostic laboratory tests that we describe below will aid physicians in diagnosing pulmonary TB efficiently.
Diagnosis ; Drug Resistance ; Incidence ; Korea ; Methods ; Mortality ; Prevalence ; Public Health ; Tuberculosis, Pulmonary

Cause of Death ; Diagnosis ; Humans ; Isoniazid ; Public Health ; Rifampin ; Tuberculosis ; Tuberculosis, Pulmonary ; World Health Organization

Tuberculosis (TB) remains a threat to public health and is the leading cause of death globally. Isoniazid (INH) is an important first-line agent for the treatment of TB considering its early bactericidal activity. Resistance to INH is now the most common type of resistance. Resistance to INH reduces the probability of treatment success and increases the risk of acquiring resistance to other first-line drugs such as rifampicin (RIF), thereby increasing the risk of multidrug-resistant-TB. Studies in the 1970s and 1980s showed high success rates for INH-resistant TB cases receiving regimens comprised of first-line drugs. However, recent data have indicated that INH-resistant TB patients treated with only first-line drugs have poor outcomes. Fortunately, based on recent systematic meta-analyses, the World Health Organization published consolidated guidelines on drug-resistant TB in 2019. Their key recommendations are treatment with RIF-ethambutol (EMB)-pyrazinamide (PZA)-levofloxacin (LFX) for 6 months and no addition of injectable agents to the treatment regimen. The guidelines also emphasize the importance of excluding resistance to RIF before starting RIF-EMB-PZA-LFX regimen. Additionally, when the diagnosis of INH-resistant TB is confirmed long after starting the first-line TB treatment, the clinician must decide whether to start a 6-month course of RIF-EMB-PZA-LFX based on the patient's condition. However, these recommendations are based on observational studies, not randomized controlled trials, and are thus conditional and based on low certainty of the effect estimates. Therefore, further work is needed to optimize the treatment of INH-resistant TB.

The incidence and prevalence of pulmonary tuberculosis (TB) in South Korea remain high despite the fact that South Korea is a high-income country, and pulmonary TB is an important public health issue in terms of both morbidity and mortality. Thus, rapid diagnosis and management of active pulmonary TB are crucial for effective TB control, which can help to prevent the transmission of TB and the occurrence of new TB cases. However, because the clinical and radiological presentations of pulmonary TB may occasionally be nonspecific, identification of causative microorganisms using laboratory tests is the most important diagnostic method. Recently-developed microbiological and molecular techniques are commonly employed in current clinical practice. In particular, advances in liquid culture system, line probe assays, and Xpert MTB/RIF assay have reduced the identification time and facilitate the identification of drug-resistance TB. However, as various tests have both advantages and limitations, physicians should be aware of the principles underpinning the tests when interpreting the results. Thus, the clinical and radiological characteristics of pulmonary TB and several diagnostic laboratory tests that we describe below will aid physicians in diagnosing pulmonary TB efficiently.

Tuberculosis (TB) remains a threat to public health and is the leading cause of death globally. Isoniazid (INH) is an important first-line agent for the treatment of TB considering its early bactericidal activity. Resistance to INH is now the most common type of resistance. Resistance to INH reduces the probability of treatment success and increases the risk of acquiring resistance to other first-line drugs such as rifampicin (RIF), thereby increasing the risk of multidrug-resistant-TB. Studies in the 1970s and 1980s showed high success rates for INH-resistant TB cases receiving regimens comprised of first-line drugs. However, recent data have indicated that INH-resistant TB patients treated with only first-line drugs have poor outcomes. Fortunately, based on recent systematic meta-analyses, the World Health Organization published consolidated guidelines on drug-resistant TB in 2019. Their key recommendations are treatment with RIF-ethambutol (EMB)-pyrazinamide (PZA)-levofloxacin (LFX) for 6 months and no addition of injectable agents to the treatment regimen. The guidelines also emphasize the importance of excluding resistance to RIF before starting RIF-EMB-PZA-LFX regimen. Additionally, when the diagnosis of INH-resistant TB is confirmed long after starting the first-line TB treatment, the clinician must decide whether to start a 6-month course of RIF-EMB-PZA-LFX based on the patient's condition. However, these recommendations are based on observational studies, not randomized controlled trials, and are thus conditional and based on low certainty of the effect estimates. Therefore, further work is needed to optimize the treatment of INH-resistant TB.