Aetiology of community acquired pneumonia in Valencia, Spain: a multicentre prospective study

Patterns and predictors of positive multiplex polymerase chain reaction respiratory panel among patients with acute respiratory infections in a single center in Lebanon

BACKGROUND

Infectious agents associated with community-acquired acute respiratory infections (ARIs) remain understudied in Lebanon. We aim to assess the microbiological profiles of ARIs by employing polymerase chain reaction (PCR) and identifying predictors of positive PCR results among patients admitted for ARI.

METHODS AND RESULTS

We conducted a retrospective single-center study at the American University of Beirut Medical Center, including all respiratory PCR panels performed on pediatric (< 18) and adult (≥ 18) patients presenting with an ARI from January 2015 to March 2018, prior to the onset of the COVID-19 pandemic. We aimed to identify the epidemiological patterns of ARIs and the factors associated with positive PCRs in both adult and pediatric patients. Among 281 respiratory PCRs, 168 (59.7%) were positive for at least one pathogen, with 54.1% positive PCR for viruses, 7.8% for bacteria species, and 3.9% with virus-bacteria codetection. Almost 60% of the patients received antibiotics prior to PCR testing. PCR panels yielded more positive results in pediatric patients than in adults (P = 0.005). Bacterial detection was more common in adults compared to pediatrics (P < 0.001). The most common organism recovered in the entire population was Human Rhinovirus (RhV) (18.5%). Patients with pleural effusion on chest CT were less likely to have a positive PCR (95% Cl: 0.22-0.99). On multivariate analysis, pediatric age group (P < 0.001), stem cell transplant (P = 0.006), fever (P = 0.03) and UTRI symptoms (P = 0.004) were all predictive of a positive viral PCR.

CONCLUSION

Understanding the local epidemiology of ARI is crucial for proper antimicrobial stewardship. The identification of factors associated with positive respiratory PCR enhances our understanding of clinical characteristics and potential predictors of viral detection in our population.

Investigating Beta-Variational Convolutional Autoencoders for the Unsupervised Classification of Chest Pneumonia

The world's population is increasing and so is the challenge on existing healthcare infrastructure to cope with the growing demand in medical diagnosis and evaluation. Although human experts are primarily tasked with the diagnosis of different medical conditions, artificial intelligence (AI)-assisted diagnoses have become considerably useful in recent times. One of the critical lung infections, which requires early diagnosis and subsequent treatment to reduce the mortality rate, is pneumonia. There are different methods for obtaining a pneumonia diagnosis; however, the adoption of chest X-rays is popular since it is non-invasive. The AI systems for a pneumonia diagnosis using chest X-rays are often built on supervised machine-learning (ML) models, which require labeled datasets for development. However, collecting labeled datasets is sometimes infeasible due to constraints such as human resources, cost, and time. As such, the problem that we address in this paper is the unsupervised classification of pneumonia using unsupervised ML models including the beta-variational convolutional autoencoder (β-VCAE) and other variants, such as convolutional autoencoders (CAE), denoising convolutional autoencoders (DCAE), and sparse convolutional autoencoders (SCAE). Namely, the pneumonia classification problem is cast into an anomaly detection to develop the aforementioned ML models. The experimental results show that pneumonia can be diagnosed with high recall, precision, f₁-score, and f₂-score using the proposed unsupervised models. In addition, we observe that the proposed models are competitive with the state-of-the-art models, which are trained on a labeled dataset.

Outcomes of respiratory viral-bacterial co-infection in adult hospitalized patients

BACKGROUND

Viral infections of the respiratory tract represent a major global health concern. Co-infection with bacteria may contribute to severe disease and increased mortality in patients. Nevertheless, viral-bacterial co-infection patterns and their clinical outcomes have not been well characterized to date. This study aimed to evaluate the clinical features and outcomes of patients with viral-bacterial respiratory tract co-infections.

METHODS

We included 19,361 patients with respiratory infection due to respiratory viruses [influenza A and B, respiratory syncytial virus (RSV), parainfluenza] and/or bacteria in four tertiary hospitals in Hong Kong from 2013 to 2017 using a large territory-wide healthcare database. All microbiological tests were conducted within 48 h of hospital admission. Four etiological groups were included: (1) viral infection alone; (2) bacterial infection alone; (3) laboratory-confirmed viral-bacterial co-infection and (4) clinically suspected viral-bacterial co-infection who were tested positive for respiratory virus and negative for bacteria but had received at least four days of antibiotics. Clinical features and outcomes were recorded for laboratory-confirmed viral-bacterial co-infection patients compared to other three groups as control. The primary outcome was 30-day mortality. Secondary outcomes were intensive care unit (ICU) admission and length of hospital stay. Propensity score matching estimated by binary logistic regression was used to adjust for the potential bias that may affect the association between outcomes and covariates.

FINDINGS

Among 15,906 patients with respiratory viral infection, there were 8451 (53.1%) clinically suspected and 1,087 (6.8%) laboratory-confirmed viral-bacterial co-infection. Among all the bacterial species, Haemophilus influenzae (226/1,087, 20.8%), Pseudomonas aeruginosa (180/1087, 16.6%) and Streptococcus pneumoniae (123/1087, 11.3%) were the three most common bacterial pathogens in the laboratory-confirmed co-infection group. Respiratory viruses co-infected with non-pneumococcal streptococci or methicillin-resistant Staphylococcus aureus was associated with the highest death rate [9/30 (30%) and 13/48 (27.1%), respectively] in this cohort. Compared with other infection groups, patients with laboratory-confirmed co-infection had higher ICU admission rate (p < 0.001) and mortality rate at 30 days (p = 0.028), and these results persisted after adjustment for potential confounders using propensity score matching. Furthermore, patients with laboratory-confirmed co-infection had significantly higher mortality compared to patients with bacterial infection alone.

INTERPRETATION

In our cohort, bacterial co-infection is common in hospitalized patients with viral respiratory tract infection and is associated with higher ICU admission rate and mortality. Therefore, active surveillance for bacterial co-infection and early antibiotic treatment may be required to improve outcomes in patients with respiratory viral infection.

Why is the rate of pneumococcal pneumonia declining?

PURPOSE OF REVIEW

As Streptococcus pneumoniae was considered the etiological agent of nearly all the cases of pneumonia at the beginning of the 20th century, and today is identified in fewer than 10-15% of cases, we analyze the possible causes of such a decline.

RECENT FINDINGS

Extensive use of early empiric antimicrobial therapy, discovery of previously unrecognized pathogens, availability to newer diagnostic methods for the recognition of the pneumonia pathogens (PCR, urinary antigens, monoclonal antibodies etc.) and of improved preventive measures, including vaccines, are some of possible explanations of the declining role of S. pneumoniae in the cause of pneumonia.

SUMMARY

The 14-valent and the 23-valent capsular polysaccharide pneumococcal vaccines were licensed in 1977 and 1983, respectively. The seven-valent protein-conjugated capsular polysaccharide vaccine, approved for routine use in children starting at 2 months of age, was highly effective in preventing invasive pneumococcal disease in children but also in adults because of the herd effect. In 2010, the 13-valent protein-conjugated capsular polysaccharide vaccine replaced seven-valent protein-conjugated capsular polysaccharide vaccine. With the use of conjugated vaccines, a decrease of the vaccine-type invasive pneumococcal disease for all age groups was observed. Both the direct effect of the vaccine and the so-called herd immunity are considered responsible for much of the decline.

Chlamydia psittaci (psittacosis) as a cause of community-acquired pneumonia: a systematic review and meta-analysis

Psittacosis is a zoonotic infectious disease caused by the transmission of the bacterium Chlamydia psittaci from birds to humans. Infections in humans mainly present as community-acquired pneumonia (CAP). However, most cases of CAP are treated without diagnostic testing, and the importance of C. psittaci infection as a cause of CAP is therefore unclear. In this meta-analysis of published CAP-aetiological studies, we estimate the proportion of CAP caused by C. psittaci infection. The databases MEDLINE and Embase were systematically searched for relevant studies published from 1986 onwards. Only studies that consisted of 100 patients or more were included. In total, 57 studies were selected for the meta-analysis. C. psittaci was the causative pathogen in 1·03% (95% CI 0·79-1·30) of all CAP cases from the included studies combined, with a range between studies from 0 to 6·7%. For burden of disease estimates, it is a reasonable assumption that 1% of incident cases of CAP are caused by psittacosis.

Role of Proteases in Lung Disease: A Brief Overview

Proteases play an important role in health and disease of the lung. In the normal lungs, proteases maintain their homeostatic functions that regulate processes like its regeneration and repair. Dysregulation of proteases–antiproteases balance is crucial in the manifestation of different types of lung diseases. Chronic inflammatory lung pathologies are associated with a marked increase in protease activities. Thus, in addition to protease activities, inhibition of anti-proteolytic control mechanisms are also important for effective microbial infection and inflammation in the lung. Herein, we briefly summarize the role of different proteases and to some extent antiproteases in regulating a variety of lung diseases.

SIRT1‑mediated regulation of oxidative stress induced by Pseudomonas aeruginosa lipopolysaccharides in human alveolar epithelial cells

Sirtuin1 (SIRT1) is an NAD+‑dependent deacetylase that exhibits multiple biological functions, including cell differentiation inhibition, transcription regulation, cell cycle regulation and anti‑apoptosis. Lipopolysaccharides (LPS) are crucial virulence factors produced by Pseudomonas aeruginosa and serve an important role in adjusting the interactions between the host and the pathogen. However, the effect of SIRT1 in the regulation of LPS‑induced A459 human alveolar epithelial cells (AECs) oxidative stress remains unclear. The cellular reactive oxygen species (ROS) production was examined in A549 cells that were supplemented with LPS. Relative cell signaling pathway proteins were further investigated by western blot analysis. It was identified that LPS downregulated SIRT1 expression, however, upregulated ROS generation, which was associated with the increase of nuclear factor (NF)‑κB and acetyl‑NF‑κB. Activation of SIRT1 by resveratrol significantly reversed the effects of LPS on A549 cells. By contrast, inhibition of SIRT1 by nicotinamide had the opposite effects that enhance cell ROS production. Thus, the results indicated that SIRT1 serves an important role in the regulation of oxidative stress induced by LPS in human AECs.

Community-acquired Pseudomonas aeruginosa-pneumonia in a previously healthy man occupationally exposed to metalworking fluids

Although the Pseudomonas aeruginosa infection is well known and frequently found in hospitals and nursing care facilities, many cases are also reported outside these boundaries. In general, this pathogen infects debilitated patients either by comorbidities or by any form of immunodeficiency. In cases of respiratory infection, tobacco abuse seems to play an important role as a risk factor. In previously healthy patients, community-acquired pneumonia (CAP) with P. aeruginosa as the etiological agent is extremely rare, and unlike the cases involving immunocompromised or hospitalized patients, the outcome is severe, and is fatal in up to 61.1% of cases. Aerosolized contaminated water or solutions are closely linked to the development of respiratory tract infection. In this setting, metalworking fluids used in factories may be implicated in CAP involving previously healthy people. The authors report the case of a middle-aged man who worked in a metalworking factory and presented a right upper lobar pneumonia with a rapid fatal outcome. P. aeruginosa was cultured from blood and tracheal aspirates. The autopsy findings confirmed a hemorrhagic necrotizing pneumonia with bacteria-invading vasculitis and thrombosis. A culture of the metalworking fluid of the factory was also positive for P. aeruginosa. The pulsed-field gel electrophoresis showed that both strains (blood culture and metalworking fluid) were genetically indistinguishable. The authors highlight the occupational risk for the development of this P.aeruginosa-infection in healthy people.

Legionella pneumonia cases over a five-year period: a descriptive, retrospective study of outcomes in a UK district hospital

As the recent outbreaks in Edinburgh and Camarthen, UK, have shown, Legionella pneumonia (LP) remains a significant public health problem, which is not only confined to those who have travelled abroad. In both outbreaks and sporadic cases, diagnosis can go unrecognised. We reviewed the demographics, comorbidities, diagnosis, treatment and clinical outcome of LP cases over five years in a district general hospital in northwest England. Over half of LP cases were UK acquired and 'classic' clinical features were common. Clinical criteria for diagnosing LP were confirmed, but few sputum samples were sent to reference laboratories, limiting further essential epidemiological mapping of UK cases. Following current UK community-acquired pneumonia guidance would have missed nearly one quarter of LP cases in our series, potentially leading to further morbidity and mortality.

Thin-section CT findings in Pseudomonas aeruginosa pulmonary infection

OBJECTIVE

The aim of this study was to assess clinical and pulmonary thin-section CT findings in patients with acute Pseudomonas aeruginosa (PA) pulmonary infection.

METHODS

We retrospectively identified 44 patients with acute PA pneumonia who had undergone chest thin-section CT examinations between January 2004 and December 2010. We excluded nine patients with concurrent infections. The final study group comprised 35 patients (21 males, 14 females; age range 30-89 years, mean age 66.9 years) with PA pneumonia. The patients' clinical findings were assessed. Parenchymal abnormalities, enlarged lymph nodes and pleural effusion were evaluated on thin-section CT.

RESULTS

Underlying diseases included malignancy (n=13), a smoking habit (n=11) and cardiac disease (n=8). CT scans of all patients revealed abnormal findings, including ground-glass opacity (n=34), bronchial wall thickening (n=31), consolidation (n=23) and cavities (n=5). Pleural effusion was found in 15 patients.

CONCLUSION

PA pulmonary infection was observed in patients with underlying diseases such as malignancy or a smoking habit. The CT findings in patients with PA consisted mainly of ground-glass attenuation and bronchial wall thickening.

ADVANCES IN KNOWLEDGE

The CT findings consisted mainly of ground-glass attenuation, bronchial wall thickening and cavities. These findings in patients with an underlying disease such as malignancy or a smoking habit may be suggestive of pneumonia caused by PA infection.

Guidelines for the management of adult lower respiratory tract infections--full version

This document is an update of Guidelines published in 2005 and now includes scientific publications through to May 2010. It provides evidence-based recommendations for the most common management questions occurring in routine clinical practice in the management of adult patients with LRTI. Topics include management outside hospital, management inside hospital (including community-acquired pneumonia (CAP), acute exacerbations of COPD (AECOPD), acute exacerbations of bronchiectasis) and prevention. Background sections and graded evidence tables are also included. The target audience for the Guideline is thus all those whose routine practice includes the management of adult LRTI.

Impact of endogenous protein C on pulmonary coagulation and injury during lethal H1N1 influenza in mice

Influenza accounts for 5-10% of community-acquired pneumonia cases, and is a major cause of mortality. Sterile and bacterial lung injury are associated with procoagulant and inflammatory derangements in the lungs and down-regulation of the protein C (PC) pathway has been correlated with disease severity and mortality in severe bacterial pneumonia and sepsis. In addition, during lethal influenza pneumonia, pulmonary and systemic coagulation are activated, which can be attenuated by the administration of recombinant activated (A) PC. We here determined the role of endogenous PC in lethal H1N1 influenza A infection. Male C57BL/6 mice pretreated with an inhibitory monoclonal antibody directed against murine PC or a control antibody were intranasally infected with a lethal dose of a mouse-adapted H1N1 influenza A strain. Mice were killed at 48 or 96 hours after infection, after which lungs and bronchoalveolar lavage fluid were harvested, or observed for up to 9 days. Anti-PC antibody treatment aggravated pulmonary activation of coagulation as compared with control antibody treatment, as reflected by increased lung concentrations of thrombin-antithrombin complexes and fibrin degradation products, as well as intravascular thrombus formation. Anti-PC antibody treatment aggravated lung histopathology, but lowered bronchoalveolar neutrophil influx and total protein levels, and delayed mortality. In conclusion, endogenous PC has strong effects on the host response to lethal influenza A infection, inhibiting pulmonary coagulopathy and inflammation on the one hand, but facilitating neutrophil influx and protein leak and accelerating mortality on the other hand.

Significance of the progression of respiratory symptoms for predicting community-acquired pneumonia in general practice

BACKGROUND AND OBJECTIVE

Early diagnosis improves outcomes in patients with community-acquired pneumonia (CAP). However, prediction of CAP based on symptoms and signs is difficult. The present study investigated the evaluation of progression of symptoms as a factor for predicting the occurrence of CAP in general practice.

METHODS

Consecutive patients (n = 406) suspected of having CAP on routine clinical examination were studied retrospectively. Selection of patients with suspected CAP was based on progression of symptoms after 5 days, as well as published criteria. Diagnostic yields for the recommended criteria and our proposed criteria were then compared. Scoring systems for the prediction of CAP were designed, based on the results of multiple regression analysis. The diagnostic performance of these systems, including or excluding symptom progression, was compared using the areas under receiver operating characteristic curves.

RESULTS

The sensitivity and specificity of the recommended criteria and our proposed criteria were 0.75 and 0.44, and 0.93 and 0.38, respectively. Sputum production, dyspnoea, fever > 38 degrees C, heart rate > 100 beats/min, decreased breath sounds, coarse crackles and progression of symptoms significantly increased the likelihood of CAP. Areas under receiver operating characteristic curves analysis showed that the diagnostic prediction of CAP was significantly improved when the scoring system included progression of symptoms.

CONCLUSIONS

Progression of symptoms was a significant factor for predicting CAP and selecting patients who required CXR. Inclusion of progression of symptoms among the other recommended criteria, namely, dyspnoea, fever > 38 degrees C, heart rate > 100 beats/min and abnormal chest findings, improved prediction of the incidence of CAP in general practice.

Activated protein C ameliorates coagulopathy but does not influence outcome in lethal H1N1 influenza: a controlled laboratory study

INTRODUCTION

Influenza accounts for 5 to 10% of community-acquired pneumonias and is a major cause of mortality. Sterile and bacterial lung injuries are associated with procoagulant and inflammatory derangements in the lungs. Activated protein C (APC) is an anticoagulant with anti-inflammatory properties that exert beneficial effects in models of lung injury. We determined the impact of lethal influenza A (H1N1) infection on systemic and pulmonary coagulation and inflammation, and the effect of recombinant mouse (rm-) APC here on.

METHODS

Male C57BL/6 mice were intranasally infected with a lethal dose of a mouse adapted influenza A (H1N1) strain. Treatment with rm-APC (125 microg intraperitoneally every eight hours for a maximum of three days) or vehicle was initiated 24 hours after infection. Mice were euthanized 48 or 96 hours after infection, or observed for up to nine days.

RESULTS

Lethal H1N1 influenza resulted in systemic and pulmonary activation of coagulation, as reflected by elevated plasma and lung levels of thrombin-antithrombin complexes and fibrin degradation products. These procoagulant changes were accompanied by inhibition of the fibrinolytic response due to enhanced release of plasminogen activator inhibitor type-1. Rm-APC strongly inhibited coagulation activation in both plasma and lungs, and partially reversed the inhibition of fibrinolysis. Rm-APC temporarily reduced pulmonary viral loads, but did not impact on lung inflammation or survival.

CONCLUSIONS

Lethal influenza induces procoagulant and antifibrinolytic changes in the lung which can be partially prevented by rm-APC treatment.

Influenza

OBJECTIVE

Influenza is a major concern for intensivists in all communities in the U.S. While there is considerable concern whether or not the country will be ready for a pandemic influenza, even seasonal influenza poses a major challenge to hospitals. The objective of this review is to summarize current knowledge of influenza with emphasis on the issues that intensivist will encounter.

SETTING

Intensive care unit in a 450-bed, tertiary care, teaching hospital.

METHODS

Source data were obtained from a PubMed search of the medical literature. PubMed "related articles" search strategies were likewise employed frequently.

SUMMARY AND CONCLUSIONS

Seasonal influenza causes more than 200,000 hospitalizations and 41,000 deaths in the U.S. every year, and is the seventh leading cause of death in the U.S. Despite this impact there is a shortcoming in knowledge of influenza among many health care workers, and a paucity of clinical data and studies to guide therapy. Intensivists need to recognize the importance of seasonal influenza as a cause of severe morbidity and mortality. This review summarizes current knowledge of the diagnosis, complications, therapy, and infection control measures associated with influenza.

Etiology of Community-Acquired Pneumonia in Hospitalized Patients in Chile

BACKGROUND AND STUDY OBJECTIVES

The range and relative impact of microbial pathogens, particularly viral pathogens, as a cause of community-acquired pneumonia (CAP) in hospitalized adults has not received much attention. The aim of this study was to determine the microbial etiology of CAP in adults and to identify the risk factors for various specific pathogens.

METHODS

We prospectively studied 176 patients (mean [+/- SD] age, 65.8 +/- 18.5 years) who had hospitalized for CAP to identify the microbial etiology. For each patient, sputum and blood cultures were obtained as well as serology testing for Mycoplasma pneumoniae and Chlamydophila pneumoniae, urinary antigen testing for Legionella pneumophila and Streptococcus pneumoniae, and a nasopharyngeal swab for seven respiratory viruses.

RESULTS

Microbial etiology was determined in 98 patients (55%). S pneumoniae (49 of 98 patients; 50%) and respiratory viruses (32%) were the most frequently isolated pathogen groups. Pneumococcal pneumonia was associated with tobacco smoking of > 10 pack-years (odds ratio [OR], 2.6; 95% confidence interval [CI], 1.2 to 5.4; p = 0.01). Respiratory viruses were isolated more often in fall or winter (28%; p = 0.011), and as an exclusive etiology tended to be isolated in patients >/= 65 years of age (20%; p = 0.07). Viral CAP was associated with antimicrobial therapy prior to hospital admission (OR, 4.5; 95% CI, 1.4 to 14.6).

CONCLUSIONS

S pneumoniae remains the most frequent pathogen in adults with CAP and should be covered with empirical antimicrobial treatment. Viruses were the second most common etiologic agent and should be tested for, especially in fall or winter, both in young and elderly patients who are hospitalized with CAP.

[Contribution of microbiological investigations to the diagnosis of lower respiratory tract infections]

The diagnosis of community-acquired pneumonia is usually based on clinical and radiological criteria. The identification of a causative organism is not required for the diagnosis. Although numerous microbiological techniques are available, their sensitivity and specificity are not high enough to guide first-line antimicrobial therapy. Consequently, this treatment remains most often empiric. If the causative organism is identified, the antimicrobial treatment is adapted. Sputum analysis may be proposed as a diagnostic tool for patients with an acute exacerbation of chronic obstructive pulmonary disease, in specific cases (prior antibiotherapy, hospitalization, failure of the empiric antimicrobial treatment).

[Antibiotherapy for acute CAP in adults]

Community acquired pneumonia is one of the most frequent infections. With time, bacterial epidemiology and bacterial resistance evolve and new antibiotics become available. So an up-date on adequate antibiotic use is necessary. We reviewed the epidemiology of pneumonia and the evolution of bacterial resistance. We also collected data on new antibiotics which can be used for this infection such as levofloxacin, moxifloxacin, telithromycin, and pristinamycin. All these drugs are effective on bacteria involved in pneumonia. At this time, only few Streptococcus pneumoniae strains have developed resistance to these drugs. However, resistance to fluoroquinolones is not easily detected with common laboratory techniques. There is no effectiveness difference between the 2 new fluoroquinolones (levofloxacin, moxifloxacin) in clinical studies. However, in bacteriological and pharmacological studies, moxifloxacin seems to be more effective than levofloxacin (500 mg/day). For the treatment of pneumonia due to Legionella pneumophila, fluoroquinolones are now widely recommended. For Streptococcus pneumonia, amoxicillin remain the drug of choice, even for bacteria with a decreased susceptibility to penicillin. The importance of treating atypical pathogens remains to be documented.

Epidemiology of community-acquired pneumonia in adult patients at the dawn of the 21st century: a prospective study on the Mediterranean coast of Spain

This study presents data from a prospective study of adult patients with community-acquired pneumonia (CAP). Of 493 patients included in the study, 223 (45.2%) were aged > or = 65 years, and 265 (53.7%) had one or more underlying diseases, mostly chronic obstructive pulmonary disease, diabetes mellitus or dementia. In total, 281 microorganisms were identified in 250 (50.7%) patients, with two or more pathogens detected in 28 (5.7%) cases. Microbial diagnosis varied according to age, severity, co-morbidity and site-of-care, but there was much overlap among groups. Streptococcus pneumoniae was the single most prevalent organism in outpatients, patients admitted to hospital, and patients who died, either as a single pathogen or combined with another organism. Infections caused by 'atypical' pathogens were seen across all groups, including the elderly and patients with co-morbidities. Mortality varied according to the pneumonia severity index (PSI) of the pneumonia patient outcomes research team. Shock (OR 34.48), an age of > 65 years (OR 25) and altered mental status (OR 9.92) were factors associated independently with 30-day mortality. Key findings from this study were the advanced age of the population with CAP, and the high prevalence of dementia as an underlying disease. The study also revealed that microbiological diagnosis of CAP remains problematic. Although certain epidemiological features may help to predict the microbial aetiology, the overlap among groups reduces the usefulness of this information in guiding therapeutic decisions. Greater effort should be made to improve identification methods for microbial pathogens causing CAP.

Community-acquired pneumonia of mixed etiology: prevalence, clinical characteristics, and outcome

Community-acquired pneumonia (CAP) of mixed etiology has increasingly been appreciated in the literature, but its clinical significance remains unknown. The aim of this analysis was to describe the prevalence, clinical characteristics, and outcome of CAP of mixed etiology. Data were obtained from a 2-year prospective study of consecutive patients with CAP in whom an extensive microbiological workup was performed. Predefined strict criteria were used to establish the etiology. A total of 493 patients were included. A single pathogen was detected in 222 (45%) cases and two or more pathogens in 28 (5.7%) cases. Mixed infections were seen across all age groups and in patients treated both in hospital and as outpatients. The most frequent combinations of pathogens were those of a bacterium plus an "atypical" organism (28.6%) and of two bacterial organisms (28.6%). Compared with patients with monomicrobial pneumonia, patients with mixed pneumonia were more likely to have underlying conditions (64% vs. 45%, p=0.04) and dementia (25% vs. 10%, p=0.02). The incidence of a defined series of complications was higher in patients with mixed pneumonia (39.3% vs. 18.6%; OR=2.84; p=0.02). Community-acquired pneumonia of mixed etiology is uncommon. Patients with mixed pneumonia are more likely to have underlying medical conditions, and they may have a more severe course of disease.

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.

[Guidelines for the management of community pneumonia in adult who needs hospitalization]

Community acquired pneumonia is still an important health problem. In Spain the year incidence is 162 cases per 100,000 inhabitants with 53,000 hospital admission costing 115 millions of euros per year. In the last years there have been significant advances in the knowledge of: aetiology, diagnostic tools, treatment alternatives and antibiotic resistance. The Spanish Societies of Intensive and Critical Care (SEMICYUC), Infectious Diseases and Clinical Microbiology (SEIMC) and Pulmonology and Thoracic Surgery (SEPAR) have produced these evidence-based Guidelines for the management of community acquired pneumonia in Adults. The main objective is to help physicians to make decisions about this disease. The different points that have been developed are: aetiology, diagnosis, treatment and prevention.

Guide to selection of fluoroquinolones in patients with lower respiratory tract infections

Newer fluoroquinolones such as levofloxacin, moxifloxacin, gatifloxacin and gemifloxacin have several attributes that make them excellent choices for the therapy of lower respiratory tract infections. In particular, they have excellent intrinsic activity against Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and the atypical respiratory pathogens. Fluoroquinolones may be used as monotherapy to treat high-risk patients with acute exacerbation of chronic bronchitis, and for patients with community-acquired pneumonia requiring hospitalisation, but not admission to intensive care. Overall, the newer fluoroquinolones often achieve clinical cure rates in > or =90% of these patients. However, rates may be lower in hospital-acquired pneumonia, and this infection should be treated on the basis of anticipated organisms and evaluation of risk factors for specific pathogens such as Pseudomonas aeruginosa. In this setting, an antipseudomonal fluoroquinolone may be used in combination with an antipseudomonalbeta-lactam. Concerns are now being raised about the widespread use, and possibly misuse, of fluoroquinolones and the emergence of resistance among S. pneumoniae, Enterobacteriaceae and P. aeruginosa. A number of pharmacokinetic parameters such as the peak concentration of the antibacterial after a dose (C(max)), and the 24-hour area under the concentration-time curve (AUC24) and their relationship to pharmacodynamic parameters such as the minimum inhibitory and the mutant prevention concentrations (MIC and MPC, respectively) have been proposed to predict the effect of fluoroquinolones on bacterial killing and the emergence of resistance. Higher C(max)/MIC or AUC24/MIC and C(max)/MPC or AUC24/MPC ratios, either as a result of dose administration or the susceptibility of the organism, may lead to a better clinical outcome and decrease the emergence of resistance, respectively. Pharmacokinetic profiles that are optimised to target low-level resistant minor subpopulations of bacteria that often exist in infections may help preserve fluoroquinolones as a class. To this end, optimising the AUC24/MPC or C(max)/MPC ratios is important, particularly against S. pneumoniae, in the setting of lower respiratory tract infections. Agents such as moxifloxacin and gemifloxacin with high ratios against this organism are preferred, and agents such as ciprofloxacin with low ratios should be avoided. For agents such as levofloxacin and gatifloxacin, with intermediate ratios against S. pneumoniae, it may be worthwhile considering alternative dose administration strategies, such as using higher dosages, to eradicate low-level resistant variants. This must, of course, be balanced against the potential of toxicity. Innovative approaches to the use of fluoroquinolones are worth testing in further in vitro experiments as well as in clinical trials.

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.

Clinical features of Q fever pneumonia

The aim of the study was to assess the clinical features of Q fever pneumonia in Japan. Four cases of Q fever pneumonia (a female aged 21 and males aged 53, 74 and 87 years) who were diagnosed using the PanBio ELISA test kit, were assessed and their clinical features are described. The frequency of Q fever pneumonia among our cases of community-acquired pneumonia was 1.4% (4/284). A 21-year-old female had a typical case of the disease with (i) a history of owning a cat, (ii) onset with fever and dry cough, (iii) multiple soft infiltrative shadows on CXR, (iv) a normal white blood cell count, and (v) good response to clarithromycin. The pneumonias in the other three cases were considered mixed infections with bacteria such as Streptococcus pneumoniae and Haemophilus influenzae. Their clinical features included the following: (i) an elderly person with an underlying disease, (ii) onset with fever and purulent sputum, (iii) coarse crackles on auscultation, (iv) infiltrative shadows and pleural effusion on CXR, (v) increased white blood cells with elevated BUN and hyponatraemia, and (vi) modest responses to combined therapy with carbapenem and minocycline. Our observations suggest that two types of pneumonia caused by Coxiella burnetti exist; one with the usual features of atypical pneumonia, and the other presenting with the clinical features of bacterial pneumonia in the elderly due to mixed bacterial infection.

Imagerie moderne des pneumonies infectieuses aiguës

Les pneumonies infectieuses aiguës constituent un problème de santé publique important, car elles sont une cause majeure de morbidité et de mortalité chez l’adulte. Si les données cliniques et radiographiques permettent le plus souvent de faire le diagnostic de pneumonie infectieuse, le diagnostic étiologique est plus difficile. En effet, de nombreux agents pathogènes peuvent être responsables de pneumonie et la réaction du parenchyme pulmonaire est peu variée, d’où la faible spécificité des lésions radiologiques observées en dehors de quelques cas particuliers. C’est pourquoi la compréhension des mécanismes physiopathologiques permet d’expliquer certains aspects radiologiques. De même, la connaissance des bases anatomocliniques et radiologiques autorise la reconnaissance de trois aspects radiographiques principaux. Quant à l’appréciation des contextes épidémiologique et immunitaire, ils peuvent permettre également d’approcher le germe en cause.

Aetiology and Clinical Presentation of Mild Community-Acquired Bacterial Pneumonia

A prospective study was initiated to analyse the bacterial aetiology and clinical picture of mild community-acquired pneumonia in Slovenia using the previously described Pneumonia Severity Index. Radiographically confirmed cases of pneumonia in patients treated with oral antibiotics in seven study centres were included. An aetiological diagnosis was attempted using culture of blood and sputum, urinary antigen testing for Streptococcus pneumoniae and Legionella pneumophila, and antibody testing for Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella pneumophila in paired serum samples. One hundred thirteen patients were evaluable for clinical presentation and 109 for aetiological diagnosis. At least one pathogen was detected in 62.4% patients. The most common causative agents were Mycoplasma pneumoniae in 24.8%, Chlamydia pneumoniae in 21.1%, and Streptococcus pneumoniae in 13.8% of patients. Dual infection was detected in 8.3% of patients. Most patients suffered from cough, fatigue, and fever. Patients with atypical aetiology of pneumonia differed from those with typical bacterial pneumonia or pneumonia of unknown aetiology in age, presence of dyspnea, and bronchial breathing on lung auscultation. Patients with pneumococcal, chlamydial, and mycoplasmal infections differed in age, risk class, presence of dyspnea, bronchial breathing, and proteinuria. There was an overlap of other clinical symptoms, underlying conditions, and laboratory and radiographic findings among the groups of patients classified by aetiology. Since patients with mild community-acquired pneumonia exhibit similar clinical characteristics and, moreover, since a substantial proportion of cases are attributable to atypical bacteria, broad-spectrum antibiotic treatment seems to be recommended.

[A comparison of moxifloxacin and amoxicillin in the treatment of community-acquired pneumonia in Latin America: results of a multicenter clinical trial]

Since community-acquired pneumonia (CAP) is a common disease with a high morbidity rate, it is important to obtain information concerning its etiology and susceptibility to antibiotics across different geographic areas. This study presents data obtained in 5 Latin American counties in the course of an international clinical trial that evaluated the efficacy and safety of treatment with either moxifloxacin or amoxicillin administered for 10 days to patients suspected of having CAP caused by a pneumococcal infection. Details are given of the pathogens identified, the patterns of sensitivity to antibiotics observed, and the clinical and microbiological results obtained.A total of 84 patients were studied, of whom 70 (83.3%) were evaluated at the end of the trial to determine the efficacy and safety of the treatment received. Gram-positive bacteria were found in samples from 29 patients (80.5%). The pathogen was Streptococcus pneumoniae in 28 of those cases (77.7%). Gram-negative bacteria were found in 7 patients (19.4%), the most common being Haemophilus influenzae in 3 patients (8.3%). The presence of atypical microorganisms was detected in 18 of the 70 patients (25%), mainly Mycobacterium pneumoniae (n=11), and in 6 cases (8.5%) the infection was mixed. Ten strains of S. pneumoniae (35.7%) were shown to be susceptible to penicillin, 2 (7.1%) were highly resistant, and 16 (57.1%) showed moderate resistance. The clinical success rate at the final visit after treatment was 94.1% for moxifloxacin and 91.7% for amoxicillin. The results of this trial demonstrate a high prevalence of S. pneumoniae with reduced susceptibility to penicillin in patients with CAP in Latin America. It also revealed a high incidence of atypical pathogens and mixed infection in 8.6% of patients. This information should be taken into account when establishing protocols for empirical treatment of CAP in Latin America.

Recomendações de abordagem diagnóstica e terapêutica da pneumonia da comunidade em adultos imunocompetentes

The Portuguese Respiratory Society makes a series of recommendations as to the state of the art of the diagnostic, therapeutic and preventive approach to community-acquired pneumonia in immunocompetent adults in Portugal. These proposals should be regarded as general guidelines and are not intended to replace the clinical sense used in resolving each individual case. Our main goal is to stratify the patients according to the risk of morbidity and mortality in order to justify the following decisions more rationally: the choice of place of treatment (outpatient or inpatient), diagnostic tests and antimicrobial therapy. We also make a set of recommendations for the prevention of CAP. We plan to conduct multi-centre prospective studies, preferably in collaboration with other scientific societies, in order to be able to characterise the situation in Portugal more accurately and regularly update this document.

Microbiological etiology in clinically diagnosed community-acquired pneumonia in primary care in Orebro, Sweden

OBJECTIVE

To study the etiology of clinically diagnosed community-acquired pneumonia (CAP) in antibiotically naive patients attending a primary care center and treated at their homes.

METHODS

A three-year prospective study was carried out, and 177 patients presenting with clinical signs of CAP were included. All patients had chest X-rays after inclusion, and 82 (46%) showed infiltrates. Nasopharyngeal swab culture was performed on all patients, and 51% produced a representative sputum sample. Paired sera were obtained from 176 patients.

RESULTS

Among the 82 patients with radiographically proven CAP, Streptococcus pneumoniae was detected in 26 patients (32%), Haemophilus influenzae in 23 (28%), Mycoplasma pneumoniae in 15 (18%), and Chlamydia pneumoniae in four (5%). Serologic evidence of a viral infection was found in 13 patients (16%). Among the 95 patients without infiltrates, S. pneumoniae was found in 21 (22%), H. influenzae in 14 (15%), M. pneumoniae in two (2%), and C. pneumoniae in five (5%). Viral infection was detected in 19 (20%) of these 95 patients.

CONCLUSION

In primary care in Sweden, the initial antibiotic treatment in any patient with pneumonia should be effective against S. pneumonia and H. influenzae. In addition, M. pneumoniae should be targeted during recurrent epidemics. C. pneumoniae, and especially Legionella, seem to be uncommon in primary care.

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.

Influence of deviation from guidelines on the outcome of community-acquired pneumonia

STUDY OBJECTIVE

s: Consensus guidelines for the empirical treatment of community-acquired pneumonia (CAP) have been published. We investigated the following factors: (1) the degree of adherence to American Thoracic Society (ATS) and the Spanish Society of Pulmonology and Thoracic Surgery (SEPAR) guidelines; and (2) the influence of adhering to these guidelines on mortality and length of hospitalization.

DESIGN

Prospective, observational study.

SETTING

Tertiary-care teaching hospital.

PATIENTS

Two hundred ninety-five patients with CAP who were consecutively admitted to the hospital and treated empirically.

INTERVENTIONS

Patients were stratified according to the prognostic rule of Fine, and the antibiotic regimen prescribed in the first 24 h was evaluated as to whether or not it adhered to treatment guidelines.

RESULTS

Adherence to SEPAR and ATS guidelines was 66% and 88%, respectively. There were no significant differences in mortality or duration of hospitalization between adherent and nonadherent regimens. However, mortality in severe CAP (Fine risk class V) was significantly higher in patients with nonadherent treatments (SEPAR: relative risk [RR], 2.6; 95% confidence interval [CI], 1.1 to 5.6; ATS: RR, 2.5; 95% CI, 1.1 to 5.8). In a multivariate analysis, adherence to ATS guidelines was independently associated with decreased mortality (RR, 0.3; 95% CI, 0.14 to 0.9) after adjusting for the Fine score.

CONCLUSIONS

Adherence was higher to ATS guidelines than to SEPAR guidelines. Severe CAP had a significantly higher mortality when the guidelines (both ATS and SEPAR) were not followed. Length of hospitalization was similar irrespective of adherence to either set of guidelines.

Applying sputum as a diagnostic tool in pneumonia: limited yield, minimal impact on treatment decisions

STUDY OBJECTIVES

We evaluated the role of sputum examination in the management of patients with community-acquired pneumonia (CAP) in a primary-care hospital without microbiologic laboratory facilities.

DESIGN AND INTERVENTIONS

A diagnostic strategy using regular collection of sputum samples, Gram staining in a local laboratory, and mailing of samples to a commercial laboratory for culture analysis.

SETTING

A 200-bed primary-care hospital without subspeciality physicians.

PATIENTS

One hundred sixteen consecutive patients with a diagnosis of CAP were prospectively evaluated during a 12-month period.

RESULTS

Of 116 patients, 42 patients (36%) were capable of producing a sputum sample. Age > or = 75 years (odds ratio [OR], 0.4; 95% confidence interval [CI], 0.18 to 0.93) and prior ambulatory antimicrobial treatment (OR, 3.2; 95% CI, 1.2 to 8.4) were independent predictors of sputum production. A delay in collection and processing of sputum samples of > 24 h was present in 31% and 39%, respectively. A delay in collection yielded an increased number of Gram-negative enteric bacilli and nonfermenters (44% vs. 7%, p = 0.056). A delay in processing was associated with an increased number of Candida spp isolates (33% vs. 9%, p = 0.16). The overall diagnostic yield was low (10 of 116 patients, 9%) due to a limited number of valid samples (n = 23 of 42 patients, 55%) and a limited number of definitely or probably positive samples on Gram's stain and culture (n = 10 of 42 patients, 24%). Prior ambulatory antimicrobial treatment was associated with a reduction in diagnostic yield (14% vs. 56%, p = 0.09). The impact of diagnostic results on antimicrobial treatment decisions was minimal, with antimicrobial treatment directed to diagnostic results in only one patient.

CONCLUSIONS

We conclude that in this setting representative of primary-care hospitals in Germany, sputum had a low diagnostic yield and did not contribute significantly to patient management.

Community-acquired pneumonia in ambulatory patients: relative importance of atypical pathogens

The presence of atypical pathogens in community-acquired pneumonia is difficult to diagnose; culture is time-consuming and requires considerable expertise and serological identification may be inaccurate. Nevertheless, the increasing importance of atypical organisms has been recognised in recent years. Variations in aetiology have been detected in different geographical regions and different patient populations. The season of the year may also influence aetiology, and some infections follow a cyclical pattern. When an atypical pathogen is suspected, a macrolide antibiotic is an appropriate choice as, in addition to activity against these organisms, they are usually effective against the Gram-positive and Gram-negative respiratory pathogens implicated in community-acquired pneumonia.