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SCIENTIFIC LETTER
Chest computed tomography for the diagnosis of Mycoplasma pneumoniae infection NAOYUKI MIYASHITA,1 HIROTO AKAIKE,2 HIDETO TERANISHI,2 TAKASHI NAKANO,2 KAZUNOBU OUCHI2 AND NIRO OKIMOTO1 1
Department of Internal Medicine 1 and 2Department of Pediatrics, Kawasaki Medical School, Okayama City, Okayama, Japan
We analysed 53 cases of laboratory-confirmed Mycoplasma pneumoniae infection with cough lasting ≥7 days and chest radiography showing no abnormal findings. Twenty-two (41%) of those patients showed abnormal findings on chest high-resolution computed tomography. In the daily clinical setting, for assessment of acute cough, physicians should be aware that it is difficult to confirm bronchiolitis or bronchopneumonia due to M. pneumoniae by chest radiography. Key words: bronchial wall thickening, centrilobular nodule, community-acquired pneumonia, high-resolution computed tomography, Mycoplasma pneumonia. Abbreviation: HRCT, high-resolution computed tomography.
Identifying abnormal findings on chest radiography in bronchiolitis or pneumonia due to Mycoplasma pneumoniae can be difficult. Chest high-resolution computed tomography (HRCT) may be more sensitive because it can detect bronchial wall thickening and centrilobular nodules that closely reflect histopathological changes caused by M. pneumoniae infection (acute cellular bronchiolitis, and peribronchial and perivascular interstitial opacities),1,2 All adult patients with cough lasting ≥7 days who visited Kawasaki Medical School Hospital between January 2009 and April 2013 were enrolled in this study. Patients meeting all following inclusion criteria underwent chest HRCT: (i) requesting a chest specialist examination because of worsening of cough symptoms despite treatment, (ii) increasing cough for ≥7 days, (iii) paroxysmal cough and/or being awakened by coughing at night, (iv) no abnormal findings on chest radiography, (v) meeting the criteria of the Japanese Respiratory Society community-acquired pneumonia guideline for the diagnosis of M. pneumoniae pneumonia scoring system,3 and (vi) accepting Correspondence: Naoyuki Miyashita, Department of Internal Medicine 1, Kawasaki Medical School, 2-1-80 Nakasange, Kita-ku, Okayama City, Okayama 700-8505, Japan. Email: nao @med.kawasaki-m.ac.jp Received 5 August 2013; invited to revise 8 September 2013; revised 12 September 2013; accepted 30 September 2013 (Associate Editor: Marcos Restrepo). © 2013 The Authors Respirology © 2013 Asian Pacific Society of Respirology
further examination. CT examination was performed as reported previously1 before antibiotics treatment. Informed consent was obtained, and the study protocol was approved by the Ethics Committee at Kawasaki Medical School. Three chest physicians, blinded to the diagnoses, retrospectively and independently assessed abnormalities findings.1 The following tests were performed: gram staining and cultures to detect bacteria Legionella species, Chlamydia species and M. pneumoniae; polymerase chain reaction to detect M. pneumoniae, Bordetella pertussis, Chlamydia species and Legionella species; and serological tests to detect viruses B. pertussis, Legionella species, Chlamydia species, Coxiella burnetii and M. pneumoniae.4 Paired serum samples were collected at intervals of at least 4 weeks after onset. M. pneumoniae was cultured with pleuropneumonia-like organism broth (Difco, Detroit, MI, USA). The M. pneumoniae-specific primers used for the polymerase chain reaction were from within the P1 cytadhesin gene. Antibodies to M. pneumoniae were measured by a passive agglutination test (Serodia-Myco II kit, Fujirebio, Tokyo, Japan). The microbial aetiology was classified as ‘definitive’, ‘presumptive’ or ‘unknown’, as described previously.4 M. pneumoniae was laboratory-confirmed in 53 cases by culture, polymerase chain reaction or serology. No cases of co-infection were observed. The time between onset of cough and CT ranged from 7 to 14 days (mean, 8.4 days). Of the 53 patients with M. pneumoniae infection (mean age 33.9 years; 24 males), 1 case was culture positive, 43 polymerase chain reaction positive and 22 serology positive. Eleven (20%) patients had comorbid illnesses such as diabetes mellitus, cardiovascular diseases and chronic liver disease. No patients had a history of chronic lung diseases or radiographic pulmonary abnormalities Twenty-two (41%) patients showed abnormal findings on chest CT. Bronchial wall thickening was observed most frequently 21 (95%), followed by centrilobular nodules 11 (50%), lymphadenopathy 9 (40%), ground-glass attenuation 7 (31%) and reticular or linear opacities 2 (9%) (Fig. 1). Underlying Respirology (2014) 19, 144–145 doi: 10.1111/resp.12218
145
Chest X-ray for M. pneumoniae infection (a)
(b)
CT images can more accurately provide detailed information about the lung parenchyma than routine chest radiography. Syrjala et al. identified pneumonia in 26 patients by HRCT versus 18 by radiography (P < 0.01) in a prospective study of 47 patients with signs of community-acquired pneumonia.5 HRCT was more sensitive than radiography in detecting lower respiratory tract infection-related lung lesions.6 In our study, 41% of patients with M. pneumoniae infection with no abnormal findings on chest radiography showed findings of bronchiolitis or bronchopneumonia on chest HRCT. The Japanese Respiratory Society guidelines provide a rapid and simple scoring system for the diagnosis of M. pneumoniae.3 Several studies have demonstrated their usefulness to distinguish between bacterial infection and M. pneumoniae infection, but for many cases they are insufficient. For these cases, HRCT may be more appropriate. Chest HRCT may also better detect refractory M. pneumoniae infection, defined as prolonged fever and deterioration of clinical findings despite administration of appropriate antibiotics. In conclusion, chest radiography is insufficient in the management of acute cough due to M. pneumoniae infection. To prevent the underdiagnosis of M. pneumoniae pneumonia, chest CT is a useful tool in patients who have paroxysmal cough lasting ≥7 days and meet the criteria of the Japanese Respiratory Society guideline scoring system.3
(c)
Acknowledgements This study was supported in part by MEXT KAKENHI (19591190 and 21591304) and Project Research Grants from Kawasaki Medical School (13-401, 14-402, 15-405A, 16-405M, 17-402M, 18-401, 19-402M and 20-4030).
REFERENCES
Figure 1 Mycoplasma pneumoniae infection cases whose chest radiograph reveals no abnormal findings. (a) 28-year-old female. High-resolution computed tomography (HRCT) shows bronchial wall thickening (arrows) and centrilobular nodules (arrowheads). (b) 53-year-old male. HRCT shows bronchial wall thickening (arrows) and centrilobular nodules (arrowheads). (c) 34-year-old male. HRCT shows bronchial wall thickening (arrows) and centrilobular nodules (tree-in-bud appearance, arrowheads). Ground-glass attenuation is also apparent.
conditions, severity of fever, clinical symptoms and laboratory data on first examination were not significantly different between patients with and without chest CT abnormalities.
© 2013 The Authors Respirology © 2013 Asian Pacific Society of Respirology
1 Miyashita N, Sugiu T, Kawai K et al. Radiographic features of Mycoplasma pneumoniae pneumonia: differential diagnosis and performance timing. BMC Med. Imaging 2009; 9: 7. 2 Ito I, Ishida T, Togashi K et al. Differentiation of bacterial and non-bacterial community-acquired pneumonia by thinsection computed tomography. Eur. J. Radiol. 2009; 72: 388–95. 3 Miyashita N, Kawai Y, Yamaguchi T et al. Clinical potential of diagnostic methods for the rapid diagnosis of Mycoplasma pneumoniae pneumonia in adults. Eur. J. Clin. Microbiol. Infect. Dis. 2011; 30: 439–46. 4 Miyashita N, Akaike H, Teranishi H et al. Diagnostic value of symptoms and laboratory data for pertussis in adolescent and adult patients. BMC Infect. Dis. 2013; 13: 129. 5 Syrjala H, Broas M, Ojala A et al. High-resolution computed tomography for the diagnosis of community-acquired pneumonia. Clin. Infect. Dis. 1998; 27: 358–63. 6 Lahde S, Jartti A, Broas M et al. HRCT findings in the lungs of primary care patients with lower respiratory tract infection. Acta Radiol. 2002; 43: 159–63.
Respirology (2014) 19, 144–145
SCIENTIFIC LETTER
Chest computed tomography for the diagnosis of Mycoplasma pneumoniae infection NAOYUKI MIYASHITA,1 HIROTO AKAIKE,2 HIDETO TERANISHI,2 TAKASHI NAKANO,2 KAZUNOBU OUCHI2 AND NIRO OKIMOTO1 1
Department of Internal Medicine 1 and 2Department of Pediatrics, Kawasaki Medical School, Okayama City, Okayama, Japan
We analysed 53 cases of laboratory-confirmed Mycoplasma pneumoniae infection with cough lasting ≥7 days and chest radiography showing no abnormal findings. Twenty-two (41%) of those patients showed abnormal findings on chest high-resolution computed tomography. In the daily clinical setting, for assessment of acute cough, physicians should be aware that it is difficult to confirm bronchiolitis or bronchopneumonia due to M. pneumoniae by chest radiography. Key words: bronchial wall thickening, centrilobular nodule, community-acquired pneumonia, high-resolution computed tomography, Mycoplasma pneumonia. Abbreviation: HRCT, high-resolution computed tomography.
Identifying abnormal findings on chest radiography in bronchiolitis or pneumonia due to Mycoplasma pneumoniae can be difficult. Chest high-resolution computed tomography (HRCT) may be more sensitive because it can detect bronchial wall thickening and centrilobular nodules that closely reflect histopathological changes caused by M. pneumoniae infection (acute cellular bronchiolitis, and peribronchial and perivascular interstitial opacities),1,2 All adult patients with cough lasting ≥7 days who visited Kawasaki Medical School Hospital between January 2009 and April 2013 were enrolled in this study. Patients meeting all following inclusion criteria underwent chest HRCT: (i) requesting a chest specialist examination because of worsening of cough symptoms despite treatment, (ii) increasing cough for ≥7 days, (iii) paroxysmal cough and/or being awakened by coughing at night, (iv) no abnormal findings on chest radiography, (v) meeting the criteria of the Japanese Respiratory Society community-acquired pneumonia guideline for the diagnosis of M. pneumoniae pneumonia scoring system,3 and (vi) accepting Correspondence: Naoyuki Miyashita, Department of Internal Medicine 1, Kawasaki Medical School, 2-1-80 Nakasange, Kita-ku, Okayama City, Okayama 700-8505, Japan. Email: nao @med.kawasaki-m.ac.jp Received 5 August 2013; invited to revise 8 September 2013; revised 12 September 2013; accepted 30 September 2013 (Associate Editor: Marcos Restrepo). © 2013 The Authors Respirology © 2013 Asian Pacific Society of Respirology
further examination. CT examination was performed as reported previously1 before antibiotics treatment. Informed consent was obtained, and the study protocol was approved by the Ethics Committee at Kawasaki Medical School. Three chest physicians, blinded to the diagnoses, retrospectively and independently assessed abnormalities findings.1 The following tests were performed: gram staining and cultures to detect bacteria Legionella species, Chlamydia species and M. pneumoniae; polymerase chain reaction to detect M. pneumoniae, Bordetella pertussis, Chlamydia species and Legionella species; and serological tests to detect viruses B. pertussis, Legionella species, Chlamydia species, Coxiella burnetii and M. pneumoniae.4 Paired serum samples were collected at intervals of at least 4 weeks after onset. M. pneumoniae was cultured with pleuropneumonia-like organism broth (Difco, Detroit, MI, USA). The M. pneumoniae-specific primers used for the polymerase chain reaction were from within the P1 cytadhesin gene. Antibodies to M. pneumoniae were measured by a passive agglutination test (Serodia-Myco II kit, Fujirebio, Tokyo, Japan). The microbial aetiology was classified as ‘definitive’, ‘presumptive’ or ‘unknown’, as described previously.4 M. pneumoniae was laboratory-confirmed in 53 cases by culture, polymerase chain reaction or serology. No cases of co-infection were observed. The time between onset of cough and CT ranged from 7 to 14 days (mean, 8.4 days). Of the 53 patients with M. pneumoniae infection (mean age 33.9 years; 24 males), 1 case was culture positive, 43 polymerase chain reaction positive and 22 serology positive. Eleven (20%) patients had comorbid illnesses such as diabetes mellitus, cardiovascular diseases and chronic liver disease. No patients had a history of chronic lung diseases or radiographic pulmonary abnormalities Twenty-two (41%) patients showed abnormal findings on chest CT. Bronchial wall thickening was observed most frequently 21 (95%), followed by centrilobular nodules 11 (50%), lymphadenopathy 9 (40%), ground-glass attenuation 7 (31%) and reticular or linear opacities 2 (9%) (Fig. 1). Underlying Respirology (2014) 19, 144–145 doi: 10.1111/resp.12218
145
Chest X-ray for M. pneumoniae infection (a)
(b)
CT images can more accurately provide detailed information about the lung parenchyma than routine chest radiography. Syrjala et al. identified pneumonia in 26 patients by HRCT versus 18 by radiography (P < 0.01) in a prospective study of 47 patients with signs of community-acquired pneumonia.5 HRCT was more sensitive than radiography in detecting lower respiratory tract infection-related lung lesions.6 In our study, 41% of patients with M. pneumoniae infection with no abnormal findings on chest radiography showed findings of bronchiolitis or bronchopneumonia on chest HRCT. The Japanese Respiratory Society guidelines provide a rapid and simple scoring system for the diagnosis of M. pneumoniae.3 Several studies have demonstrated their usefulness to distinguish between bacterial infection and M. pneumoniae infection, but for many cases they are insufficient. For these cases, HRCT may be more appropriate. Chest HRCT may also better detect refractory M. pneumoniae infection, defined as prolonged fever and deterioration of clinical findings despite administration of appropriate antibiotics. In conclusion, chest radiography is insufficient in the management of acute cough due to M. pneumoniae infection. To prevent the underdiagnosis of M. pneumoniae pneumonia, chest CT is a useful tool in patients who have paroxysmal cough lasting ≥7 days and meet the criteria of the Japanese Respiratory Society guideline scoring system.3
(c)
Acknowledgements This study was supported in part by MEXT KAKENHI (19591190 and 21591304) and Project Research Grants from Kawasaki Medical School (13-401, 14-402, 15-405A, 16-405M, 17-402M, 18-401, 19-402M and 20-4030).
REFERENCES
Figure 1 Mycoplasma pneumoniae infection cases whose chest radiograph reveals no abnormal findings. (a) 28-year-old female. High-resolution computed tomography (HRCT) shows bronchial wall thickening (arrows) and centrilobular nodules (arrowheads). (b) 53-year-old male. HRCT shows bronchial wall thickening (arrows) and centrilobular nodules (arrowheads). (c) 34-year-old male. HRCT shows bronchial wall thickening (arrows) and centrilobular nodules (tree-in-bud appearance, arrowheads). Ground-glass attenuation is also apparent.
conditions, severity of fever, clinical symptoms and laboratory data on first examination were not significantly different between patients with and without chest CT abnormalities.
© 2013 The Authors Respirology © 2013 Asian Pacific Society of Respirology
1 Miyashita N, Sugiu T, Kawai K et al. Radiographic features of Mycoplasma pneumoniae pneumonia: differential diagnosis and performance timing. BMC Med. Imaging 2009; 9: 7. 2 Ito I, Ishida T, Togashi K et al. Differentiation of bacterial and non-bacterial community-acquired pneumonia by thinsection computed tomography. Eur. J. Radiol. 2009; 72: 388–95. 3 Miyashita N, Kawai Y, Yamaguchi T et al. Clinical potential of diagnostic methods for the rapid diagnosis of Mycoplasma pneumoniae pneumonia in adults. Eur. J. Clin. Microbiol. Infect. Dis. 2011; 30: 439–46. 4 Miyashita N, Akaike H, Teranishi H et al. Diagnostic value of symptoms and laboratory data for pertussis in adolescent and adult patients. BMC Infect. Dis. 2013; 13: 129. 5 Syrjala H, Broas M, Ojala A et al. High-resolution computed tomography for the diagnosis of community-acquired pneumonia. Clin. Infect. Dis. 1998; 27: 358–63. 6 Lahde S, Jartti A, Broas M et al. HRCT findings in the lungs of primary care patients with lower respiratory tract infection. Acta Radiol. 2002; 43: 159–63.
Respirology (2014) 19, 144–145
