Etiology of community-acquired pneumonia requiring hospitalization 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.

Identification of priority pathogens for aetiological diagnosis in adults with community-acquired pneumonia in China: a multicentre prospective study

BACKGROUND

Community-acquired pneumonia (CAP) is a major public health challenge worldwide. However, the aetiological and disease severity-related pathogens associated with CAP in adults in China are not well established based on the detection of both viral and bacterial agents.

METHODS

A multicentre, prospective study was conducted involving 10 hospitals located in nine geographical regions in China from 2014 to 2019. Sputum or bronchoalveolar lavage fluid (BALF) samples were collected from each recruited CAP patient. Multiplex real-time PCR and bacteria culture methods were used to detect respiratory pathogens. The association between detected pathogens and CAP severity was evaluated.

RESULTS

Among the 3,403 recruited eligible patients, 462 (13.58%) had severe CAP, and the in-hospital mortality rate was 1.94% (66/3,403). At least one pathogen was detected in 2,054 (60.36%) patients, with two or more pathogens were co-detected in 725 patients. The ten major pathogens detected were Mycoplasma pneumoniae (11.05%), Haemophilus influenzae (10.67%), Klebsiella pneumoniae (10.43%), influenza A virus (9.49%), human rhinovirus (9.02%), Streptococcus pneumoniae (7.43%), Staphylococcus aureus (4.50%), adenovirus (2.94%), respiratory syncytial viruses (2.35%), and Legionella pneumophila (1.03%), which accounted for 76.06-92.52% of all positive detection results across sampling sites. Klebsiella pneumoniae (p < 0.001) and influenza viruses (p = 0.005) were more frequently detected in older patients, whereas Mycoplasma pneumoniae was more frequently detected in younger patients (p < 0.001). Infections with Klebsiella pneumoniae, Staphylococcus aureus, influenza viruses and respiratory syncytial viruses were risk factors for severe CAP.

CONCLUSIONS

The major respiratory pathogens causing CAP in adults in China were different from those in USA and European countries, which were consistent across different geographical regions over study years. Given the detection rate of pathogens and their association with severe CAP, we propose to include the ten major pathogens as priorities for clinical pathogen screening in China.

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.

Time Trend of the Sensitivity of the Pneumococcal Urinary Antigen Test for Diagnosing Pneumococcal Community-Acquired Pneumonia: An Analysis of 15-Year, Prospective Cohort Data

Introduction

Whether the sensitivity of the BinaxNOW Streptococcus pneumoniae urinary antigen test kit (BinaxNOW), adjusted by some variables including vital signs, laboratory examinations and pneumonia severity, has been decreasing is unknown. The aim of the present study was to investigate whether BinaxNOW sensitivity has decreased recently and to identify the predictors of the BinaxNOW result, including the time trend.

Methods

This prospective cohort study enrolled consecutive patients with pneumococcal community-acquired pneumonia who were hospitalised at Kurashiki Central Hospital from January 2001 to December 2015. Pneumococcal community-acquired pneumonia was defined as positive blood or pleural effusion or sputum culture results. To evaluate the effect of the time trend for the sensitivity of BinaxNOW, time series regression analysis was performed. In addition, predictors of the BinaxNOW result were examined by multivariable analysis using variables such as sex, vital signs, blood tests such as C-reactive protein, albumin, blood urea nitrogen, creatinine, white blood cell count, haematocrit and platelets, antibiotic pre-treatment, bacteraemia, and pneumonia severity, in addition to time trend and seasonality.

Results

A total of 446 patients were included. BinaxNOW sensitivity showed a significant, gradual decrease from 2001 (81.3%) to 2015 (48.7%). On multivariable analysis [odds ratio (95% confidence interval)], bacteraemia [2.516 (1.387–4.561), P = 0.002] was a predictor of a positive BinaxNOW result, whereas male sex [0.467 (0.296–0.736), P = 0.001], white blood cell count [0.959 (0.930–0.989), P = 0.008] and the time trend per year [0.900 (0.859–0.943), P < 0.001] were predictors of a negative BinaxNOW result.

Conclusions

The sensitivity of BinaxNOW decreased over a 15-year period. We should be careful when interpreting BinaxNOW results in daily clinical practice, and the development of a new kit with good sensitivity is anticipated.

Trial registration number

UMIN000004353.

Predictors and usefulness of targeted therapy for pneumococcal community-acquired pneumonia diagnosed by the urinary antigen test: a prospective, observational cohort study

The aim of the present study was to investigate the predictors of targeted therapy (TT) for pneumococcal community-acquired pneumonia (PCAP) with a positive urinary antigen test (UAT) and compare the outcomes with those of nontargeted therapy. This prospective cohort study enrolled consecutive PCAP patients with a positive UAT who were hospitalized at Kurashiki Central Hospital from October 2010 to November 2019. A total of 286 patients were included. Of them, 56 patients (19.6%) were included in the TT group. On multivariate analysis, identification of Gram-positive diplococci by Gram stain (OR [95% CI]: 2.46 [1.32-4.63]) was a positive predictor, whereas aspiration pneumonia (0.17 [0.03-0.59]) and CURB-65 score (0.59 [0.42-0.81]) were negative predictors of TT. Initial treatment failure and 30-day mortality were not significantly different. The UAT is not used enough for TT, and TT for PCAP did not have worse outcomes.

Community-Acquired Pneumonia in the Asia-Pacific Region

Community-acquired pneumonia (CAP) is an important cause of mortality and morbidity worldwide. Aging population, dense urbanization, and poor access to health care make the Asia-Pacific region vulnerable to CAP. The high incidence of CAP poses a significant health and economic burden in this region. Common etiologic agents in other global regions including Streptococcus pneumoniae, Mycoplasma pneumoniae, Haemophilus influenzae, Chlamydophila pneumoniae, Staphylococcus aureus, and respiratory viruses are also the most prevalent pathogens in the Asia-Pacific region. But the higher incidence of Klebsiella pneumoniae and the presence of Burkholderia pseudomallei are unique to the region. The high prevalence of antimicrobial resistance in S. pneumoniae and M. pneumoniae has been raising the need for more prudent use of antibiotics. Emergence and spread of community-acquired methicillin-resistant S. aureus deserve attention, while the risk has not reached significant level yet in cases of CAP. Given a clinical and socioeconomic importance of CAP, further effort to better understand the epidemiology and impact of CAP is warranted in the Asia-Pacific region.

Bath water contamination with Legionella and nontuberculous mycobacteria in 24-hour home baths, hot springs, and public bathhouses of Nagano Prefecture, Japan

Bath water samples were collected from 116 hot springs, 197 public bathhouses, and 38 24-hour home baths in Nagano Prefecture, Japan, during the period of April 2009 to November 2011, for determining the presence and extent of contamination with Legionella and nontuberculous mycobacteria. Cultures positive for Legionella were observed in 123 of the 3,314 bath water samples examined. The distribution and abundance of Legionella and/or combined contamination with Legionella and nontuberculous mycobacteria were investigated to clarify the contamination levels. The abundance of Legionella was demonstrated to correlate considerably with the levels of combined contamination with Legionella and nontuberculous mycobacteria. Legionella spp. were obtained from 61% of the water samples from 24-hour home baths, but only from 3% of the samples from public bathhouses and hot springs. This is despite the fact that a few outbreaks of Legionnaires' disease in Nagano Prefecture as well as other regions of Japan have been traced to bath water contamination. The comparatively higher rate of contamination of the 24-hour home baths is a matter of concern. It is therefore advisable to routinely implement good maintenance of the water basins, particularly of the 24-hour home baths.

Comparison of Five PCR Assays for DetectingChlamydophila pneumoniaeDNA

We compared five different polymerase chain reaction (PCR) assays for the detection of Chlamydophila pneumoniae DNA using highly purified elementary bodies (EBs) and peripheral blood mononuclear cells (PBMCs) from healthy blood donors. The primers were as follows; two targeting the 16S rRNA gene, one targeting the ompA gene, one targeting the Pst-I gene, and one targeting the 53 kDa outer membrane protein gene. The 16S rRNA touchdown enzyme time release (TETR) PCR, the ompA nested PCR and the 53 kDa nested PCR were the most sensitive assays and could detect one or more EB per assay. These three PCRs also had the same reproducibility, but the minimal amount of C. pneumoniae that could be reproducibly detected (10 of 10 testing positive) was 20 EBs. In a sample of specimens from healthy blood donors, we found 5 of 77 (6.5%) PBMCs specimens to have C. pneumoniae DNA according to the nested ompA PCR. Specimens with the 16S rRNA TETR and 53 kDa nested assays were found to have C. pneumoniae DNA 7 of 77 (9.1%) and 18 of 77 (23.4%) specimens, respectively. The other two assays failed to detect even a single positive. However, the detection rate decreased with repeated testing of the same samples. Our newly designed 53 kDa nested PCR may be as useful as the other four recommended PCR assays and may be a more useful assay for the detection of C. pneumoniae DNA from PBMCs.

Prediction of the pathogens that are the cause of pneumonia by the battlefield hypothesis

Commensal organisms are frequent causes of pneumonia. However, the detection of these organisms in the airway does not mean that they are the causative pathogens; they may exist merely as colonizers. In up to 50% cases of pneumonia, the causative pathogens remain unidentified, thereby hampering targeting therapies. In speculating on the role of a commensal organism in pneumonia, we devised the battlefield hypothesis. In the "pneumonia battlefield," the organism-to-human cell number ratio may be an index for the pathogenic role of the organism. Using real-time PCR reactions for sputum samples, we tested whether the hypothesis predicts the results of bacteriological clinical tests for 4 representative commensal organisms: Streptococcus pneumoniae, Haemophilus influenzae, Pseudomonas spp., and Moraxella catarrhalis. The cutoff value for the organism-to-human cell number ratio, above which the pathogenic role of the organism was suspected, was set up for each organism using 224 sputum samples. The validity of the cutoff value was then tested in a prospective study that included 153 samples; the samples were classified into 3 groups, and each group contained 93%, 7%, and 0% of the samples from pneumonia, in which the pathogenic role of Streptococcus pneumoniae was suggested by the clinical tests. The results for Haemophilus influenzae, Pseudomonas spp., and Moraxella catarrhalis were 100%, 0%, and 0%, respectively. The battlefield hypothesis enabled legitimate interpretation of the PCR results and predicted pneumonia in which the pathogenic role of the organism was suggested by the clinical test. The PCR reactions based on the battlefield hypothesis may help to promote targeted therapies for pneumonia. The prospective observatory study described in the current report had been registered to the University Hospital Medical Information Network (UMIN) registry before its initiation, where the UMIN is a registry approved by the International Committee of Medical Journal Editors (ICMJE). The UMIN registry number was UMIN000001118: A prospective study for the investigation of the validity of cutoff values established for the HIRA-TAN system (April 9, 2008).

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.

Efficacy of azithromycin in the treatment of community-acquired pneumonia, including patients with macrolide-resistant Streptococcus pneumoniae infection

BACKGROUND AND OBJECTIVE

The growing problem of drug resistance among respiratory pathogens in community-acquired pneumonia (CAP), particularly Streptococcus pneumoniae, (S. pneumoniae) has complicated initial empiric therapy of CAP. This study was undertaken to evaluate the efficacy and tolerability of a 3-day course of azithromycin in adults with mild to moderately severe CAP, and to determine whether in vitro macrolide resistance among strains of S. pneumoniae is related to clinical efficacy/failure.

METHODS

An open-label, non-comparative study was undertaken at 3 university-affiliated hospitals in Japan. Patients were eligible if they were 18 years or older and had mild or moderately severe CAP. All patients received azithromycin 500 mg/day for three days, and clinical and microbiological responses were evaluated 1 and 2 weeks after initiating therapy.

RESULTS

A total of 78 patients received the study medication, 59 of whom had sufficient data available for efficacy analysis. Overall, a good clinical response with azithromycin was achieved in 49 patients (83.1%) and a microbiological response was achieved in 78.3%. Azithromycin resistance, based on CLSI criteria, was demonstrated in 85.7% (12/14) of S. pneumoniae isolates, and the presence of ermB genes was found in 50.0% (7/14). However, among patients in whom S. pneumoniae was isolated (n=17), a good clinical response was achieved in 76.5% (13/17), and the microbiological response rate was 64.3% (9/14). Furthermore, 6 of 7 patients in whom high-level resistance was documented (MICs >256 microg/mL and carrying ermB genes) exhibited good clinical responses. Azithromycin was well tolerated; adverse events, mainly of a gastrointestinal nature, were recorded in 6 patients (7.7%).

CONCLUSION

Most patients responed well to azithromycin, indicating that azithromycin might be clinically effective for the treatment of CAP with macrolide-resistant S. pneumoniae. However, a larger study is necessary to prove the efficacy against macrolide-resistant S. pneumoniae.

A clinical comparative study of piperacillin and sulbactam/ampicillin in patients with community-acquired bacterial pneumonia

OBJECTIVE

To evaluate the clinical usefulness of piperacillin (4 g/day) therapy for community-acquired pneumonia compared to sulbactam/ampicillin (6 g/day).

METHODS

A randomized prospective clinical study was conducted in patients with mild to severe community-acquired bacterial pneumonia.

RESULTS

The overall clinical efficiency of piperacillin therapy (4 g/day) in these patients (41/53=77.4%) was comparable to that of sulbactam/ampicillin therapy (6 g/day: efficiency rate: 33/49=67.3%), when each therapy was administered intravenously for 3-7 days. With regards to clinical efficiency based on disease severity, bacteriological efficiency, improvement in chest X-ray findings and adverse reactions, the two therapies were comparable, even though we found more efficiency for patients who had underlying diseases and there were also cost benefits in piperacillin therapy, compared with sulbactam/ampicillin therapy

CONCLUSION

The results suggested that piperacillin therapy has good efficiency and tolerability and that it may be highly effective, even in cases of pneumonia with underlying diseases. This regimen may thus serve as a first line treatment of community-acquired pneumonia.

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.

Prospective multicenter study of the causative organisms of community-acquired pneumonia in adults in Japan

Although a wide variety of recognized pathogens causes community-acquired pneumonia, the precise etiology in Japan remains unknown. We prospectively investigated the etiology in 232 patients with community-acquired pneumonia who visited 20 community-general hospitals. New diagnostic methods, using polymerase chain reaction (PCR) assays and urinary antigen tests were employed, in addition to conventional methods. The frequency of identification of causative pathogens was high (73.3%), and the leading organism was Streptococcus pneumoniae (24.6%), followed by Haemophilus influenzae (18.5%), viruses (16.4%), Chlamydia pneumoniae (6.5%), Mycoplasma pneumoniae (5.2%), and Legionella spp. (3.9%). S. pneumoniae and M. pneumoniae were the most prevalent pathogens in younger patients, and S. pneumoniae and H. influenzae were the most prevalent in elderly patients. Multiple or mixed infections were found in 25.9% of all patients and in 35.3% with a causal diagnosis. The results have important practical implications for the initial treatment of adult patients with community-acquired pneumonia.

Clinical comparative study of sulbactam/ampicillin and imipenem/cilastatin in elderly patients with community-acquired pneumonia

OBJECTIVE

To evaluate the clinical usefulness of sulbactam/ampicillin therapy for community-acquired pneumonia in the elderly.

METHODOLOGY

A randomized prospective clinical study was conducted in the elderly patients with moderate-to-severe community-acquired bacterial pneumonia.

RESULTS

Overall clinical efficacy of sulbactam/ampicillin therapy (6 g/day) in these patients (efficacy rate: 91.4%) was comparable to that of imipenem/cilastatin therapy (1 g/day; efficacy rate: 87.5%), when each therapy was administered intravenously twice daily for 7-14 days. With regard to clinical efficacy based on disease severity, bacteriological efficacy, improvement of chest X-ray findings and adverse reactions, the two therapies were comparable.

CONCLUSION

These results suggest that sulbactam/ampicillin therapy has excellent efficacy and tolerability and that it may be highly effective, even in severe cases of pneumonia. This regimen may thus serve as first-line treatment for the treatment of community-acquired pneumonia in elderly patients.

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.

Legionella pneumonia due to exposure to 24-hour bath water contaminated by Legionella pneumophila serogroup-5

A 79-year-old man was admitted to hospital from his nursing home for treatment of pneumonia, but died 7 days after admission. Legionella pneumonia was diagnosed after isolation of Legionella pneumophila serogroup-5 from sputum culture. The environment of the nursing home was investigated; only water specimens from the 24-hour bath were positive by culture for Legionella pneumophila serogroup-5. Subsequent analysis by pulsed-field gel electrophoresis revealed an identical pattern in isolates from both sputum culture and 24 hour bath water culture. Among 123 inpatients and staff of the nursing home, 17 were found to be seropositive for Legionella pneumophila serogroup-5.

A 3-year prospective study of a urinary antigen-detection test for Streptococcus pneumoniae in community-acquired pneumonia: utility and clinical impact on the reported etiology

To evaluate the efficacy of a rapid immunochromatographic membrane test (ICT) for the detection of Streptococcus pneumoniae urinary antigen for diagnosing S. pneumoniae pneumonia, ICT was performed with urine samples using the Binax NOW Streptococcus pneumoniae kit at the time of admission. The results were compared with those from conventional microbiological studies. Three hundred and forty-nine adult patients with CAP who were admitted to the hospital were studied prospectively between February 2001 and January 2004. The ICT test was positive in 115 (33.0%) of 349 patients enrolled into the study and in 63 (75.9%) of 83 patients with pneumococcal pneumonia confirmed by conventional methods. The test revealed a sensitivity of 75.9% and a specificity of 94.0% with conventional microbiological criteria used as the reference standard. The positive predictive value was 91.3%, and the negative predictive value was 82.6%. The clinical features of 53 patients in whom ICT was positive and no pathogen was identified showed no significant difference from those of 83 patients who had pneumococcal pneumonia identified by conventional methods. The diagnostic yield of pneumococcal pneumonia was increased up to 38.9% using ICT combined with conventional methods. The Binax NOW ICT to detect S. pneumoniae urinary antigen is therefore a rapid and useful method for diagnosing pneumococcal pneumonia. Induction of ICT will prove the predominance of S. pneumoniae in the etiology of CAP.

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

The Japanese Respiratory Society (JRS) published the guidelines for the management of community-acquired pneumonia in 2000. The guidelines set up nine parameters and criteria for the differential diagnosis of atypical pneumonia and bacterial pneumonia based on clinical symptoms, physical signs and laboratory data. To evaluate the performance of these guideline criteria, 91 cases of Chlamydia pneumoniae (53 cases were pure-C. pneumoniae and 38 cases were mixed-C. pneumoniae pneumonia), 103 cases of Mycoplasma pneumoniae (86 cases were pure-M. pneumoniae and 17 cases were mixed-M. pneumoniae pneumonia) and 144 cases of bacterial (Streptococcus pneumoniae and/or Haemophilus influenzae) pneumonia were analyzed. The accordance rate for a suspected atypical pneumonia with the guideline criteria was 84.8% for pure-M. pneumoniae pneumonia and 60.3% for pure-C. pneumoniae pneumonia, but only 9.0% for bacterial pneumonia, 12.1% for mixed-C. pneumoniae pneumonia and 16.6% for mixed-M. pneumoniae pneumonia. Overall, the sensitivity and specificity of the criteria in the JRS guidelines were 75.5% and 90.9%, respectively. Our results indicated that the differentiation of pneumonia in the JRS guidelines is useful for the diagnosis of M. pneumoniae pneumonia, but difficult to apply to the diagnosis of C. pneumoniae pneumonia.

Multiplex PCR for the simultaneous detection of Chlamydia pneumoniae, Mycoplasma pneumoniae and Legionella pneumophila in community-acquired pneumonia

A multiplex polymerase chain reaction (PCR) was developed for the simultaneous detection of Chlamydia pneumoniae, Mycoplasma pneumoniae and Legionella pneumophila. Oligonucleotide primers for the amplification of the DNA of these three organisms were optimized for use in combination in the same reaction. PCR products were detected by the Micro-Chip Electrophoresis Analysis System. Clinical samples were obtained from 208 community-acquired pneumonia (CAP) patients who were participants in a multicenter CAP surveillance study performed at seven medical schools and their affiliate hospitals in Japan. No significant differences in the sensitivity of each primer set were observed when tested in both the multiplex and monoplex PCR assays. Our multiplex PCR was able to reliably detect 10 copies/100 microl of each of the three pathogen DNAs. Of the panel of 208 samples, 14 of 15 C. pneumoniae, 10 of 10 M. pneumoniae, eight of eight L. pneumophila and 165 of 176 negative samples were correctly identified. Eleven cases who were the multiplex PCR positive and conventional method negative were observed. The PCR findings were of possible significance in at least four of these patients. Our multiplex PCR assay could potentially be used as a diagnostic and epidemiological tool. Further prospective studies are needed to establish its clinical usefulness.

Community-acquired pneumonia

This seminar reviews important features and management issues of community-acquired pneumonia (CAP) that are especially relevant to immunocompetent adults in light of new information about cause, clinical course, diagnostic testing, treatment, and prevention. Streptococcus pneumoniae remains the most important pathogen; however, emerging resistance of this organism to antimicrobial agents has affected empirical treatment of CAP. Atypical pathogens have been quite commonly identified in several prospective studies. The clinical significance of these pathogens (with the exception of Legionella spp) is not clear, partly because of the lack of rapid, standardised tests. Diagnostic evaluation of CAP is important for appropriate assessment of severity of illness and for establishment of the causative agent in the disease. Until better rapid diagnostic methods are developed, most patients will be treated empirically. Antimicrobials continue to be the mainstay of treatment, and decisions about specific agents are guided by several considerations that include spectrum of activity, and pharmacokinetic and pharmacodynamic principles. Several factors have been shown to be associated with a beneficial clinical outcome in patients with CAP. These factors include administration of antimicrobials in a timely manner, choice of antibiotic therapy, and the use of a critical pneumonia pathway. The appropriate use of vaccines against pneumococcal disease and influenza should be encouraged. Several guidelines for management of CAP have recently been published, the recommendations of which are reviewed.

Community-acquired pneumonia in southeast Asia: the microbial differences between ambulatory and hospitalized patients

STUDY OBJECTIVES

To determine microbial agents causing community-acquired pneumonia (CAP) in Southeast Asia.

DESIGN

A prospective study.

SETTING

Three general hospitals in Thailand.

PATIENTS

Two hundred forty-five adult patients fulfilling the clinical criteria of CAP from September 1998 to April 2001.

INTERVENTIONS

Investigations included sputum Gram stain and culture, blood culture, pleural fluid culture (if presented), urine antigen for Legionella pneumophila and Streptococcus pneumoniae, and serology for Mycoplasma pneumoniae, Chlamydia pneumoniae, and L pneumophila.

RESULTS

There were 98 outpatients and 147 hospitalized patients included in the study, and an organism was identified in 74 of 98 outpatients (75.5%) and 105 of 147 of the hospitalized patients (71.4%). C pneumoniae (36.7%), M pneumoniae (29.6%), and S pneumoniae (13.3%) were the most frequent causative pathogens found in outpatients, while S pneumoniae (22.4%) and C pneumoniae (16.3%) were the most common in hospitalized patients. There was a significantly higher incidence of C pneumoniae (36.7% vs 16.3%, respectively; p < 0.001) and M pneumoniae (29.6% vs 6.8%; p < 0.001, respectively) in the outpatients than in the hospitalized patients. The incidence of S pneumoniae, L pneumophila, and mixed infections was not different between the groups. Mixed infections were presented in 13 of 98 outpatients (13.3%) and 9 of 147 hospitalized patients (6.1%), with C pneumoniae being the most frequent coinfecting pathogen.

CONCLUSIONS

The data indicate that the core organisms causing CAP in Southeast Asia are not different from those in the Western countries. The guidelines for the treatment of patients with CAP, therefore, should be the same.

Clinical presentation of community-acquired Chlamydia pneumoniae pneumonia in adults

STUDY OBJECTIVE

To investigate the clinical presentation of community-acquired Chlamydia pneumoniae pneumonia in adults.

DESIGN

Prospective study.

SETTING

Kawasaki Medical School Hospital, Kawasaki Medical School Kawasaki Hospital, and Kurashiki Daiichi Hospital in Japan.

PARTICIPANTS

Forty patients with community-acquired pneumonia with C pneumoniae as the only pathogen identified admitted to three hospitals between April 1996 and March 2001 and their clinical presentations were compared to patients with Streptococcus pneumoniae and Mycoplasma pneumoniae pneumonia.

MEASUREMENTS

The diagnosis of C pneumoniae infection was based on isolation and serologic testing of antibodies by the microimmunofluorescence test.

RESULTS

The clinical presentations, except for shortness of breath, were similar for the three major etiologic agents. The mean temperature of C pneumoniae patients on hospital admission was 37.9 degrees C, which was lower than that of patients with S pneumoniae and M pneumoniae. The mean WBC count on hospital admission was lower in the patients with C pneumoniae (mean, 9,100/microL) than in those with S pneumoniae pneumonia but higher than in those with M pneumoniae pneumonia. No patients required respiratory support or admission to an ICU, and no deaths occurred among the C pneumoniae pneumonia patients.

CONCLUSIONS

Our results indicate that C pneumoniae pneumonia as a single etiologic agent is mild and that the underlying conditions and clinical symptoms closely resemble those of S pneumoniae pneumonia. However, the physical examinations, laboratory findings, and prognostic factors of the C pneumoniae patients resembled those of patients with M pneumoniae pneumonia.

Etiology and management of community-acquired pneumonia in Asia

The causative organisms of community-acquired pneumonia, especially in Japan and Korea, are essentially similar to those in Western countries. If there are any differences, these are due to the laboratory tests and criteria used to define pathogenicity. Overall, Streptococcus pneumoniae is the most frequently occurring pathogen and Haemophilus influenzae, Mycoplasma pneumoniae, Chlamydia pneumoniae and viruses follow. Legionella spp. look likely to be low frequency pathogens in Asian countries, but a reason for this might be limitations of the laboratory tests used. A high frequency of Gram-negative bacilli as pathogens of community-acquired pneumonia in some Asian countries may be due to different criteria used to identify disease-causing organisms. A small number of papers about antibiotic resistance have shown no large differences between Asian countries, but considerable differences to Western countries, such as frequency of macrolide-resistant S. pneumoniae. Some Asian countries have their own guidelines for community-acquired pneumonia, but these are written in their own languages.

Recent advances in the epidemiology, prevention, diagnosis, and treatment of fungal pneumonia

Although pneumonia caused by fungi is not a common occurrence in the general population, disease in an enlarging immunocompromised population is encountered with increasing frequency. Fungal pneumonias are most frequently caused by Aspergillus spp., dimorphic fungi and Cryptococcus neoformans. Recent studies have identified risk factors of thrombocytopenia, environmental events (such as construction or renovation) and immunosuppressive drug therapies as being specific risk factors for invasive fungal disease in select patient populations. Diagnostic strategies to detect circulating antigens and polymerase chain reaction based detection systems have been explored to improve identification prior to the progressive advanced disease. Advances in prophylactic strategies include increased use of aerosolized formulations of amphotericin B, usually in conjunction with new and old systemic antifungal agents. Despite recent published guidelines for treatment of fungal pneumonia based on etiology, mortality remains high in some infections with advanced disease. Caspofungin, a new echinocandin antifungal, has recently been approved by the US Food and Drug Administration for the treatment of invasive Aspergillus infections in patients unresponsive to or unable to receive amphotericin B. A triazole antifungal, voriconazole, has shown promise in phase III clinical trials in patients with refractory fungal infections and is expected to be available in early 2002. Other echinocandin and triazole antifungals are under development in attempts to provide improved effective therapy for fungal pneumonia.

In vitro and in vivo activities of sitafloxacin against Chlamydia spp

The in vitro and in vivo antichlamydial activity of sitafloxacin was investigated. The MICs and minimal chlamydiacidal concentrations of sitafloxacin for various species of chlamydia ranged from 0.031 to 0.125 microg/ml. Sitafloxacin had an excellent therapeutic effect on experimental Chlamydia psittaci pneumonia and was more potent than tosufloxacin, ofloxacin, and ciproflxacin, although slightly less potent than sparfloxacin.