Is it possible to distinguish between atypical pneumonia and bacterial pneumonia?: evaluation of the guidelines for community-acquired pneumonia in Japan

Validation of JRS atypical pneumonia score in patients with community-acquired Chlamydia psittaci pneumonia

INTRODUCTION

The Japanese Respiratory Society (JRS) atypical pneumonia score is a useful tool for the rapid presumptive diagnosis of atypical pneumonia. We investigated the clinical features of community-acquired pneumonia (CAP) due to Chlamydia psittaci and validated the JRS atypical pneumonia score in patients with C. psittaci CAP.

METHODS

This study was conducted at 30 institutions and assessed a total of 72 sporadic cases with C. psittaci CAP, 412 cases with Mycoplasma pneumoniae CAP, and 576 cases with Streptococcus pneumoniae CAP.

RESULTS

Sixty-two of 72 patients with C. psittaci CAP had a history of avian exposure. Among the six parameters of the JRS score, matching rates of four parameters were significantly lower in the C. psittaci CAP than the M. pneumoniae CAP in the following parameters: age <60 years, no or minor comorbid illness, stubborn or paroxysmal cough, and absence of chest adventitious sounds. The sensitivity of the diagnosis of atypical pneumonia in patients with C. psittaci CAP was significantly lower than the M. pneumoniae CAP (65.3% and 87.4%, p < 0.0001). When the diagnostic sensitivity was analyzed for different ages, the diagnostic sensitivities for the C. psittaci CAP were 90.5% for non-elderly patients and 30.0% for elderly patients.

CONCLUSIONS

The JRS atypical pneumonia score is a useful tool for distinguishing between C. psittaci CAP and bacterial CAP in patients aged <60 years, but not in patients aged ≥60 years. A history of avian exposure in middle-aged patients with normal white blood cell count may be suggestive of C. psittaci pneumonia.

Changes in diagnostic usefulness of the JRS scoring system in COVID-19 pneumonia by SARS-CoV-2 vaccination

INTRODUCTION

The Japanese Respiratory Society (JRS) scoring system is a useful tool for the rapid presumptive diagnosis of atypical pneumonia in non-elderly (aged <60 years) patients. As SARS-CoV-2 vaccination progresses, COVID-19 in elderly people has markedly reduced. We investigated changes in diagnostic usefulness of the JRS scoring system in COVID-19 pneumonia between the Delta variant group (vaccination period) and non-Delta variant group (before the vaccination period).

METHODS

This study was conducted at five institutions and assessed a total of 1121 patients with COVID-19 pneumonia (298 had the Delta variant). During the vaccination period, the Delta variant has spread and replaced the Alfa variant. We evaluated the vaccination period as the Delta variant group.

RESULTS

Among the six parameters of the JRS scoring system, matching rates of two parameters were higher in the Delta variant group than the non-Delta variant group (pre-vaccination period): age <60 years (77.5% vs 42.2%, P < 0.0001) and no or minor comorbid illness (69.1% vs 57.8%, p = 0.0007). The sensitivity of the diagnosis of atypical pneumonia in patients with COVID-19 pneumonia was significantly higher in the Delta variant group compared with the non-Delta variant group (80.2% vs 58.3%, p < 0.0001). When the diagnostic sensitivity was analyzed for different ages, the diagnostic sensitivities for the Delta variant and non-Delta variant groups were 92.6% and 95.5% for non-elderly patients and 39.1% and 32.5% for elderly patients, respectively.

CONCLUSIONS

Our results demonstrated that the JRS scoring system is a useful tool for distinguishing between COVID-19 pneumonia and bacterial pneumonia in the COVID-19 vaccination period, but not before the vaccination period.

Clinical Differences between Community-Acquired Mycoplasma pneumoniae Pneumonia and COVID-19 Pneumonia

Mycoplasmapneumoniae is one of the major causative pathogens of community-acquired pneumonia (CAP). M. pneumoniae CAP is clinically and radiologically distinct from bacterial CAPs. One feature of the Japanese Respiratory Society (JRS) guidelines is a trial to be carried out to differentiate between M. pneumoniae pneumonia and bacterial pneumonia for the selection of antibiotics. The purpose of the present study was to clarify the clinical and radiological differences of the M. pneumoniae CAP and coronavirus disease 2019 (COVID-19) CAP. This study was conducted at 5 institutions and assessed a total of 210 patients with M. pneumoniae CAP and 956 patients with COVID-19 CAP. The median age was significantly younger in patients with M. pneumoniae CAP than COVID-19 CAP. Among the clinical symptoms, cough and sputum were observed more frequently in patients with M. pneumoniae CAP than those with COVID-19 CAP. However, the diagnostic specificity of these findings was low. In contrast, loss of taste and anosmia were observed in patients with COVID-19 CAP but not observed in those with M. pneumoniae CAP. Bronchial wall thickening and nodules (tree-in-bud and centrilobular), which are chest computed tomography (CT) features of M. pneumoniae CAP, were rarely observed in patients with COVID-19 CAP. Our results demonstrated that there were two specific differences between M. pneumoniae CAP and COVID-19 CAP: (1) the presence of loss of taste and/or anosmia and (2) chest CT findings.

Atypical pneumonia: Pathophysiology, diagnosis, and treatment

Atypical pneumonia is caused by atypical pathogens that are not detectable with Gram stain and cannot be cultured using standard methods. The most common causative organisms of atypical pneumonia are Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella species. The therapeutic approach for atypical pneumonias is different than that for typical pneumonia. Typical bacterial pathogens classically respond to β-lactam antimicrobial therapy because they have a cell wall amenable to β-lactam disruption. On the contrary, most atypical pathogens do not have a bacterial cell wall, some are intracellular (e.g., Legionella), and some are paracellular (e.g., M. pneumoniae). To prevent an increase in the number of antimicrobial-resistant strains, the Japanese pneumonia guidelines have proposed a differential diagnosis for typical bacterial pneumonia and atypical pneumonia to select an appropriate antibiotic for the management of mild-to-moderate pneumonia. The guidelines have set up six parameters and criteria based on the clinical symptoms, physical signs, and laboratory data. However, in the elderly individuals and patients with underlying diseases, the differential diagnosis may be difficult or a mixed infection may be latent. Therefore, in these individuals, the administration of a β-lactam drug plus a macrolide or tetracycline, or only fluoroquinolone should be considered from the beginning to cover bacterial and atypical pneumonia.

Management of community-acquired pneumonia in immunocompetent adults: updated Swedish guidelines 2017

Based on expert group work, Swedish recommendations for the management of community-acquired pneumonia in adults are here updated. The management of sepsis-induced hypotension is addressed in detail, including monitoring and parenteral therapy. The importance of respiratory support in cases of acute respiratory failure is emphasized. Treatment with high-flow oxygen and non-invasive ventilation is recommended. The use of statins or steroids in general therapy is not found to be fully supported by evidence. In the management of pleural infection, new data show favourable effects of tissue plasminogen activator and deoxyribonuclease installation. Detailed recommendations for the vaccination of risk groups are afforded.

Influence of age on the clinical differentiation of atypical pneumonia in adults

BACKGROUND AND OBJECTIVE

The Japanese Respiratory Society (JRS) scoring system is a useful tool for the early and simple presumptive diagnosis of atypical pneumonia (Mycoplasma pneumoniae and Chlamydia pneumoniae pneumonia). However, it has been suggested that it is difficult to diagnose atypical pneumonia in the elderly using this system. In the present study, we evaluated the accuracy and usefulness of the JRS scoring system for diagnosing atypical pneumonia in different age groups.

METHODS

Cases of M. pneumoniae (n = 262), C. pneumoniae (n = 98) and common bacterial pneumonia (n = 364) were analysed.

RESULTS

For both atypical pneumonias, the frequency of comorbid illnesses and being in a higher risk category were significantly greater in elderly (age ≥60 years) than in non-elderly patients (age <60 years). One or more additional aetiological factors were more frequently present in elderly than in non-elderly patients. The diagnostic sensitivity and specificity for atypical pneumonia were 39% and 88%, respectively, in the elderly group, and 86% and 88%, respectively, in the non-elderly group. When the patients were stratified into 10-year age groups, the diagnostic sensitivity was highest in the 18- to 29-year age group and decreased from the youngest to the oldest age group.

CONCLUSIONS

These results indicate that it is difficult to distinguish between atypical pneumonia and bacterial pneumonia in the elderly using the JRS scoring system. When treating patients aged ≥60 years, physicians should use fluoroquinolones or β-lactam antibiotics + macrolides as empirical first-choice drugs so as to always provide antibiotic protection against potential atypical pathogens.

Rapid clinical diagnosis of Legionnaires' disease during the "herald wave" of the swine influenza (H1N1) pandemic: the Legionnaires' disease triad

BACKGROUND

In adults hospitalized with atypical community-acquired pneumonia (CAP), Legionnaires' disease is not uncommon. Legionnaire's disease can be differentiated from typical CAPs and from other atypical CAPs based on its characteristic pattern of extrapulmonary organ involvement. The first clinically useful diagnostic weighted point score system for the clinical diagnosis of Legionnaires' disease was developed by the Infectious Disease Division at Winthrop-University Hospital in the 1980s. It has proven to be diagnostically accurate and useful for more than two decades, but was time-consuming. Because Legionella spp. diagnostic tests are time-dependent and problematic, a need was perceived for a rapid, simple way to render a clinical, syndromic diagnosis of Legionnaires' disease pending Legionella test results. During the "herald wave" of the swine influenza (H1N1) pandemic in the New York area, our hospital, like others, was inundated with patients who presented to the Emergency Department with influenza-like illnesses (ILIs) for H1N1 testing/evaluation. Most patients with ILIs did not have swine influenza. Hospitalized patients with ILIs who tested positive with rapid influenza diagnostic tests (RIDTs) were placed on influenza precautions and treated with oseltamivir. Unfortunately, approximately 30% of adult patients admitted with an ILI had negative RIDTs. Because the definitive laboratory diagnosis of H1N1 pneumonia by reverse transcription-polymerase chain reaction(RT-PCR), testing was restricted by health departments, resulted in clinical and infection control dilemmas in determining which RIDT-negative patients did, in fact, have H1N1 pneumonia.

OBJECTIVE

Accordingly, a diagnostic weighted point score system was developed for H1N1 pneumonia patients, based on RT-PCR positivity by the Infectious Disease Division at Winthrop-University Hospital. This diagnostic point score system for hospitalized adults with negative RIDTs was time-consuming. As the pandemic progressed, a simplified diagnostic swine influenza (H1N1) triad was developed for the rapid clinical diagnosis of probable H1N1 pneumonia, which also differentiated it from its mimics as well as from bacterial pneumonia, eg, Legionnaires' disease. During the "herald wave" of the H1N1 pandemic, we noticed an unexplained increase in Legionnaires' disease CAPs. Because clinical resources were stressed to the maximum during the pandemic, it was critically important to rapidly identify patients rapidly with Legionnaire's disease who did not require influenza precautions or oseltamivir, but who did require anti-Legionella antimicrobial therapy.

METHODS

Based on the Winthrop-University Hospital Infectious Disease Division's diagnostic weighted point score system for Legionnaires' disease (modified), key indicators were identified and became the basis for the diagnostic Legionnaires' disease triad. The diagnostic Legionnaires' disease triad was used to make a clinical diagnosis of Legionnaires' disease until the results of Legionella diagnostic tests were reported. The diagnostic Legionnaires' disease triad diagnosed Legionnaires' disease in hospitalized adults with CAPs with extrapulmonary findings (atypical CAP) and relative bradycardia, accompanied by any three (ie, a triad) of the following: otherwise unexplained relative lymphopenia, early/mildly elevated serum transaminases (SGOT/SGPT), highly increased ferritin levels (> or =2 x n), or hypophosphatemia. The diagnostic Legionnaires' disease triad provides clinicians with a rapid way to clinically diagnose Legionnaires' disease, pending Legionella test results.

RESULTS

The accuracy of the diagnostic Legionnaires' disease triad was confirmed in our 9 cases of Legionnaires' disease by subsequent Legionella diagnostic testing.

CONCLUSIONS

The diagnostic Legionnaires' disease triad is particularly useful in situations where a rapid clinical syndromic diagnosis is needed, ie, during an H1N1 pandemic.

Atypical pneumonia--time to breathe new life into a useful term?

The term atypical pneumonia was originally used to describe an unusual presentation of pneumonia. It is now more widely used in reference to either pneumonia caused by a relatively common group of pathogens, or to a distinct clinical syndrome the existence of which is difficult to demonstrate. As such, the use of atypical pneumonia is often inaccurate, potentially confusing, and of dubious scientific merit. We need to return to the original meaning of atypical pneumonia and restrict its use to describe pneumonia that is truly unusual in clinical presentation, epidemiology, or both.

Radiographic features of Mycoplasma pneumoniae pneumonia: differential diagnosis and performance timing

BACKGROUND

The Japanese Respiratory Society guidelines propose a differential diagnosis for atypical pneumonia and bacterial pneumonia using a scoring system for the selection of appropriate antibiotic. In order to improve this scoring system, the guidelines are seeking new specific parameter. The purpose of this study was to clarify the pattern of abnormalities with Mycoplasma pneumoniae pneumonia on chest computed tomography (CT) and whether the radiographic findings could distinguish M. pneumoniae pneumonia from Streptococcus pneumoniae pneumonia.

METHODS

A retrospective review was performed of the CT findings of 64 cases and 68 cases where M. pneumoniae and S. pneumoniae, respectively, were the only pathogen identified by the panel of diagnostic tests used.

RESULTS

Of the 64 patients with M. pneumoniae pneumonia, bronchial wall thickening was observed most frequently (81%), followed by centrilobular nodules (78%), ground-glass attenuation (78%), and consolidation (61%). Bronchial wall thickening and centrilobular nodules were observed more often in M. pneumoniae patients than in S. pneumoniae patients (p < 0.0001). The presence of bilateral bronchial wall thickening or centrilobular nodules was only seen in patients with M. pneumoniae pneumonia. Using the scoring system of the Japanese Respiratory Society guidelines and chest CT findings, 97% of M. pneumoniae patients were suspected to be M. pneumoniae pneumonia without serology. When comparing the CT findings between early stage and progressed stage in the same patients with severe pneumonia, the radiographic features of early stage M. pneumoniae pneumonia were not observed clearly in the progressed stage.

CONCLUSION

The present results indicate that the diagnosis of M. pneumoniae pneumonia would appear to be reliable when found with a combination of bronchial wall thickening and centrilobular nodules in the CT findings. However, these CT findings are not observed in progressed severe M. pneumoniae pneumonia patients.

Atypical pneumonias: current clinical concepts focusing on Legionnaires' disease

PURPOSE OF REVIEW

This review provides clinicians with an overview of the clinical features of the atypical pneumonias. Atypical community-acquired pneumonia pathogens cause systemic infections with pneumonia. The key to the clinical diagnosis of atypical pneumonias depends on recognizing the characteristic pattern of extrapulmonary organ involvement different for each pathogen. As Legionella is likely to present as severe pneumonia and does not respond to beta-lactams, it is important to presumptively diagnose Legionnaires' disease clinically so that Legionella coverage is included in empiric therapy. This study reviews the clinical features and nonspecific laboratory markers of atypical pathogens, focusing on Legionnaires' disease.

RECENT FINDINGS

Case reports/outbreaks increase our understanding of Legionnaires' disease transmission. Both Mycoplasma pneumoniae and Chlamydophilia pneumoniae may cause asthma. Antimicrobial therapy of Chlamydophilia pneumoniae/Mycoplasma pneumoniae is important to decrease person-to-person spread and to decrease potential long-term sequelae.

SUMMARY

Atypical pulmonary pathogens cause systemic infections accompanied by a variety of characteristic extrapulmonary features. Clinically, it is possible to differentiate Legionnaires' disease from the other typical/atypical pneumonias. Rapid clinical diagnosis of atypical pathogens, particularly Legionnaires' disease, is important in selecting effective empiric therapy and prompting definitive laboratory testing.

Clinical differentiation of atypical pneumonia using Japanese guidelines

BACKGROUND AND OBJECTIVE

Atypical pneumonia occupies an important position in community-acquired pneumonia. The aim of this study was to examine whether making a diagnosis of atypical pneumonia is possible based upon the Japanese Respiratory Society guidelines.

METHODS

The data from three prospective studies were reviewed. A total of 285 patients with mycoplasmal pneumonia or chlamydial pneumonia and 515 patients with pneumococcal pneumonia or Haemophilus influenzae pneumonia were assessed to determine whether these pneumonias met the diagnostic criteria for atypical pneumonia used in the Japanese Respiratory Society guidelines. The criteria were: (i) age less than 60 years; (ii) no or only minor underlying diseases; (iii) persistent cough; (iv) limited chest auscultatory findings; (v) no sputum, or no identified aetiological agent by rapid diagnosis; and (vi) a peripheral white blood cell count below 10,000/microL.

RESULTS

All items of the criteria proved to be valid except for 'age' in patients with Chlamydophila pneumoniae pneumonia using multiple regression analysis. The sensitivity and specificity for atypical pneumonia were 77.0% and 93.0% based on four or more of the criteria respectively.

CONCLUSION

Pure atypical pneumonia can be differentiated to some degree by clinical symptoms and laboratory findings. It is important to differentiate and treat bacterial pneumonia and atypical pneumonia in regions such as Japan, where Streptococcus pneumoniae resistance to macrolides is high. Treatment covering the two types of pneumonia should be considered in elderly patients and those with underlying respiratory disease.

The JRS guidelines for the management of community-acquired pneumonia in adults: an update and new recommendations

Community-acquired pneumonia (CAP) continues to be a major medical problem. Since CAP is a potentially fatal disease, early appropriate antibiotic treatment is vital. Epidemiologic studies have shown that in the combined cause-of-death category, pneumonia ranks fourth as the leading cause of death in Japan. Therefore, the Japanese Respiratory Society (JRS) provided guidelines for the management of CAP in adults in 2000. Because of evolving resistance to antimicrobials and advances in diagnosis, treatment and prevention of CAP, it is felt that an update should be provided every three years so that important developments can be highlighted and pressing questions can be answered. Thus, the guidelines committee updated its guidelines in 2005. The basic policy and main purposes of the JRS guidelines include; 1) prevention of bacterial resistance and 2) effective and long-term use of medical resources. The JRS guidelines have recommended the exclusion of potential and broad spectrum antibiotics, fluoroquinolones and carbapenems, from the list of first-choice drugs for empirical treatment. In addition, the JRS guidelines have recommended short-term usage of antibiotics of an appropriate dose and pathogen-specific treatment using rapid diagnostic methods if possible.

Community-acquired pneumonia in Japan: a prospective ambulatory and hospitalized patient study

In this study the aetiology of community-acquired pneumonia (CAP) in Japan was investigated and the incidence of causative pathogens in ambulatory and hospitalized patients was compared. In addition, the roles of Chlamydophila felis and Chlamydophila pecorum as causes of CAP were investigated. Five hundred and six patients with CAP who visited an outpatient clinic or were admitted to one of three different hospitals were enrolled in this study; 106 of them were outpatients and 400 were hospitalized patients. Among the 506 CAP cases, Mycoplasma pneumoniae was the most common pathogen found in the outpatients and Streptococcus pneumoniae was the most common in the hospitalized patients. No cases of Chlamydophila pecorum pneumonia were observed and only one patient had an antibody titre suggestive of recent infection with the feline strain of Chlamydophila. The incidence of infection with M. pneumoniae and Chlamydophila pneumoniae was higher among the outpatients than among hospitalized patients, whereas the incidence of infection with S. pneumoniae and Haemophilus influenzae was higher among the hospitalized patients. Recognition of these results will allow prompt and appropriate antimicrobial therapy to be provided using Japanese CAP guidelines.