Study of community acquired pneumonia aetiology (SCAPA) in adults admitted to hospital: implications for management guidelines

Validation of a prediction rule for prognosis of severe community-acquired pneumonia

In a previous study, we developed a prognostic prediction rule, based on nine prognostic variables, capable to estimate and to adjust the mortality rate of patients admitted in intensive care unit for severe community-acquired pneumonia. A prospective multicenter study was undertaken to evaluate the performance of this rule. Five hundred eleven patients, over a 7-year period, were studied. The ICU mortality rate was 29.0%. In the 3 initial risk classes, we observed significantly increasing mortality rates (8.2% in class I, 22.8% in class II and 65.0% in class III) (p<0.001). Within each initial risk class, the adjustment risk score identified subclasses exhibiting significantly different mortality rates: 3.9% and 33.3% in class I; 3.1%, 12.9% and 63.3% in class II; and 55.8% and 82.5% in class III. Compared with mortality rates predicted by our previous study, only a few significant differences were observed. Our results demonstrate the performance and reproductibility of this prognostic prediction rule.

Aetiological diagnosis of community acquired pneumonia: utility of rapid microbiological methods with respect to disease severity

The present study investigated the utility of rapid microbiological methods in the aetiological diagnosis of community acquired pneumonia (CAP) according to the severity of CAP. Between 1999 and 2004, 384 adult patients with CAP were studied prospectively. In addition to standard microbiological methods, PCR and antigen detection techniques were used to identify pathogens. A total of 230 microbial agents in 209 patients were identified, with 134 (58.2%) identified by antigen detection or PCR tests. Of these 134 microbial agents, 95 (70.9%) were identified only by these rapid methods. Streptococcus pneumoniae urinary antigen detection was positive in 24.3% (81/333) of the patients with a diagnostic yield of 38.7% in those with severe pneumonia. Respiratory viral antigen detection was positive in 11.1% (35/314) of the patients with the highest diagnostic yield (20.3%) in patients with severe pneumonia. Mycoplasma pneumoniae PCR was positive in 7.5% (13/174) of the patients, all of whom were low-risk patients. Only 1 case of Chlamydia pneumoniae was identified by PCR. In conclusion, besides yielding the aetiological diagnosis rapidly, new methods add to the total diagnostic yield in CAP. The diagnostic yield of rapid methods differs according to the severity of the pneumonia.

Impaired opsonization with C3b and phagocytosis of Streptococcus pneumoniae in sera from subjects with defects in the classical complement pathway

Results from studies using mice deficient in specific complement factors and clinical data on patients with an inherited deficiency of the classical complement pathway component C2 suggest that the classical pathway is vital for immunity to Streptococcus pneumoniae. However, the consequences of defects in classical pathway activity for opsonization with C3b and the phagocytosis of different S. pneumoniae serotypes in human serum are not known, and there has not been a systematic analysis of the abilities of sera from subjects with a C2 deficiency to opsonize S. pneumoniae. Hence, to investigate the role of the classical pathway in immunity to S. pneumoniae in more detail, flow cytometry assays of opsonization with C3b and the phagocytosis of three capsular serotypes of S. pneumoniae were performed using human sera depleted of the complement factor C1q or B or sera obtained from C2-deficient subjects. The results demonstrate that, in human serum, the classical pathway is vital for C3b-iC3b deposition onto cells of all three serotypes of S. pneumoniae and seems to be more important than the alternative pathway for phagocytosis. Compared to the results for sera from normal subjects, C3b-iC3b deposition and total anti-S. pneumoniae antibody activity levels in sera obtained from C2(-/-) subjects were reduced and the efficiency of phagocytosis of all three S. pneumoniae strains was impaired. Anticapsular antibody levels did not correlate with phagocytosis or C3b-iC3b deposition. These data confirm that the classical pathway is vital for complement-mediated phagocytosis of S. pneumoniae and demonstrate why subjects with a C2 deficiency have a marked increase in susceptibility to S. pneumoniae infections.

Epidemiology, clinical and economic outcomes of admission hyponatremia among hospitalized patients

BACKGROUND

Hyponatremia, the most frequent electrolyte derangement identified among hospitalized patients, is associated with worsened outcomes in patients with pneumonia, heart failure and other disorders.

RESEARCH DESIGN AND METHODS

We performed a retrospective cohort study of hospitalized patients to quantify the attributable influence of admission hyponatremia on hospital costs and outcomes. Data were derived from a large administrative database with laboratory components, representing 198,281 discharges from 39 US hospitals from January 2004 to December 2005. Hyponatremia was defined as admission serum [Na(+)]<135 mEq/L.

RESULTS

The incidence of hyponatremia at admission was 5.5% (n=10,899). Patients with hyponatremia were older (65.7+/-19.6 vs. 61.5+/-21.8, p<0.001) and had a higher Deyo-Charlson Comorbidity Index score (1.8+/-2.1 vs. 1.3+/-1.8, p<0.001) than those with normal [Na(+)]. A higher proportion of hyponatremic patients required intensive care unit (ICU) (17.3% vs. 10.9%, p<0.001) and mechanical ventilation (MV) (5.0% vs. 2.8%, p<0.001) within 48 hours of hospitalization. Hospital mortality (5.9% vs. 3.0%, p<0.001), mean length of stay (HLOS, 8.6+/-8.0 vs. 7.2+/-8.2 days, p<0.001) and costs ($16,502+/-$28,984 vs. $13,558+/-$24,640, p<0.001) were significantly greater among patients with hyponatremia than those without. After adjusting for confounders, hyponatremia was independently associated with an increased need for ICU (OR 1.64, 95% CI 1.56-1.73) and MV (OR 1.68, 95% CI 1.53-1.84), and higher hospital mortality (OR 1.55, 95% CI 1.42-1.69). Hyponatremia also contributed an increase in HLOS of 1.0 day and total hospital costs of $2,289.

CONCLUSIONS

Hyponatremia is common at admission among hospitalized patients and is independently associated with a 55% increase in the risk of death, substantial hospital resource utilization and costs. Potential for bias inherent in the retrospective cohort design is the main limitation of our study. Studies are warranted to explore how prompt normalization of [Na(+)] may impact these outcomes.

The role of Streptococcus pneumoniae virulence factors in host respiratory colonization and disease

Streptococcus pneumoniae is a Gram-positive bacterial pathogen that colonizes the mucosal surfaces of the host nasopharynx and upper airway. Through a combination of virulence-factor activity and an ability to evade the early components of the host immune response, this organism can spread from the upper respiratory tract to the sterile regions of the lower respiratory tract, which leads to pneumonia. In this Review, we describe how S. pneumoniae uses its armamentarium of virulence factors to colonize the upper and lower respiratory tracts of the host and cause disease.

Severity scores for community-acquired pneumonia

An assessment of the severity of illness of a patient is one of the most important components of their early management. It guides decisions regarding the most appropriate site of care and the selection of empiric antibiotic therapy. In recent years, prediction tools, known as severity scores, have been promoted to assist early assessments of the severity of illness for patients with community-acquired pneumonia. Several different severity scores now exist and these have been modified over time. Each tool has particular strengths and weaknesses. This article reviews the evolution of severity scores for patients with community-acquired pneumonia and compares their performance in different patient cohorts for different outcomes of interest, as described in the published literature to date. It also discusses how these tools could be evaluated more comprehensively so that their place in patient management can be better appreciated.

The role of the macrophage in lung disease mediated by bacteria

Respiratory infections are a major cause of human morbidity and a leading cause of death. The lower respiratory tract is a sterile environment and host defense is well developed to clear bacteria. This response includes both humeral factors and resident and recruited cells. The alveolar macrophage is an integral component and its long-lifespan aids function. Following low-dose challenge alveolar macrophages clear bacteria from the lung, employing an over-lapping set of microbicidal strategies. At a higher-dose the phagocytic capacity of alveolar macrophages is overwhelmed but alveolar macrophages help orchestrate the inflammatory response. In the resolution phase of infection alveolar macrophages contribute to apoptosis induction and clearance of recruited cells. This process down-regulates pro-inflammatory cytokine production. Macrophage function is controlled by induction of apoptosis. Delayed-onset macrophage apoptosis contributes both to bacterial clearance and to resolution of the inflammatory response. Mcl-1, an anti-apoptotic protein with a very short half-life, is a key regulator of macrophage survival and therefore of host responses to common bacterial pathogens in the lung. Studies involving Streptococcus pneumoniae and other respiratory bacteria are discussed to illustrate these points and ephasise that the timing of macrophage apoptosis is important in determining its overall effect on the host pathogen interaction.

Predicting mortality with pneumonia severity scores: importance of model recalibration to local settings

In patients with community-acquired pneumonia (CAP) prediction rules based on individual predicted mortalities are frequently used to support decision-making for in-patient vs. outpatient management. We studied the accuracy and the need for recalibration of three risk prediction scores in a tertiary-care University hospital emergency-department setting in Switzerland. We pooled data from patients with CAP enrolled in two randomized controlled trials. We compared expected mortality from the original pneumonia severity index (PSI), CURB65 and CRB65 scores against observed mortality (calibration) and recalibrated the scores by fitting the intercept alpha and the calibration slope beta from our calibration model. Each of the original models underestimated the observed 30-day mortality of 11%, in 371 patients admitted to the emergency department with CAP (8.4%, 5.5% and 5.0% for the PSI, CURB65 and CRB65 scores, respectively). In particular, we observed a relevant mortality within the low risk classes of the original models (2.6%, 5.3%, and 3.7% for PSI classes I-III, CURB65 classes 0-1, and CRB65 class 0, respectively). Recalibration of the original risk models corrected the miscalibration. After recalibration, however, only PSI class I was sensitive enough to identify patients with a low risk (i.e. <1%) for mortality suitable for outpatient management. In our tertiary-care setting with mostly referred in-patients, CAP risk scores substantially underestimated observed mortalities misclassifying patients with relevant risks of death suitable for outpatient management. Prior to the implementation of CAP risk scores in the clinical setting, the need for recalibration and the accuracy of low-risk re-classification should be studied in order to adhere with discharge guidelines and guarantee patients' safety.

Community-Acquired Pneumonia—Back to Basics

Lower respiratory tract infections are among the most common infectious diseases worldwide and are caused by the inflammation and consolidation of lung tissue due to an infectious agent.¹ The clinical criteria for the diagnosis include chest pain, cough, auscultatory findings such as rales or evidence of pulmonary consolidation, fever, or leukocytosis.

Serum amyloid P aids complement-mediated immunity to Streptococcus pneumoniae

The physiological functions of the acute phase protein serum amyloid P (SAP) component are not well defined, although they are likely to be important, as no natural state of SAP deficiency has been reported. We have investigated the role of SAP for innate immunity to the important human pathogen Streptococcus pneumoniae. Using flow cytometry assays, we show that SAP binds to S. pneumoniae, increases classical pathway–dependent deposition of complement on the bacteria, and improves the efficiency of phagocytosis. As a consequence, in mouse models of infection, mice genetically engineered to be SAP-deficient had an impaired early inflammatory response to S. pneumoniae pneumonia and were unable to control bacterial replication, leading to the rapid development of fatal infection. Complement deposition, phagocytosis, and control of S. pneumoniae pneumonia were all improved by complementation with human SAP. These results demonstrate a novel and physiologically significant role for SAP for complement-mediated immunity against an important bacterial pathogen, and provide further evidence for the importance of the classical complement pathway for innate immunity.

Serum amyloid P (SAP) is a protein that is found in high concentrations in the blood, the exact function(s) of which are not clear. However, no known natural state of SAP deficiency has been identified, which suggests that SAP does have a vital role in human health. SAP can bind to molecular patterns found on the surface of bacteria, and it has been proposed that this may mark bacteria for attack by the immune system. We have investigated whether SAP helps protect against an important bacterial pathogen, Streptococcus pneumoniae. We show that SAP binds to different strains of S. pneumoniae, and that this leads to activation of an important component of the immune response called the complement system. Complement is particularly important for defence against S. pneumoniae infections, and using animal models of infection, we demonstrate that loss of SAP makes mice more susceptible to S. pneumoniae pneumonia. These results suggest that SAP helps the immune system to recognise invasion by bacteria and describe a new mechanism required for control of S. pneumoniae infections. This study may help the design of new therapeutic strategies to prevent or treat important bacterial diseases.

Rapid diagnosis of pneumococcal pneumonia among HIV-infected adults with urine antigen detection

OBJECTIVES

Streptococcus pneumoniae is the leading cause of bacterial pneumonia and associated bacteremia during HIV infection. Rapid diagnostic assays may limit inappropriate therapy.

METHODS

Clinical signs and symptoms and sera and urine were collected prospectively from 70 adults with pneumococcal pneumonia, including 47 with HIV co-infection. Pneumococcal C-polysaccharide antigen was detected in urine using the Binax immunochromatographic test (ICT). A systematic review of 24 published studies was conducted.

RESULTS

Clinical symptoms, signs, and laboratory parameters except leukocytosis, were similar in HIV-infected and HIV-seronegative pneumonia. The performance of the urine antigen ICT was independent of HIV-status (sensitivity 81%, specificity 98%, positive (PPV) and negative predictive values (NPV) 98%, and 82%, respectively). The sensitivity of sputum Gram's stain was 58% (34/59) with sputum unable to be provided by 16%. The CRP response was identical in HIV-infected (mean+/-SD) 133+/-88 vs. seronegative 135+/-104 mg/L (p=0.9). In the systematic review, the ICT performance revealed 74% sensitivity (95% CI 72-77%) and 94% specificity (95% CI 93-95%). Urine antigen testing increases etiologic diagnosis by 23% (range: 10-59%) when testing adults with community acquired pneumonia of unknown etiology.

CONCLUSIONS

Urinary antigen detection provides a credible rapid diagnostic test for pneumococcal pneumonia regardless of HIV-status. CRP response to acute infection is similar in HIV co-infection and increases diagnostic certainty.

Differences in the etiology of community-acquired pneumonia according to site of care: A population-based study

BACKGROUND

A few population-based studies assessing the etiology of community-acquired pneumonia in both hospitalized and ambulatory patients, with special emphasis on the etiologic role of viral infections, have been reported. The purpose of this study was to assess microbiological differences according to initial site of care in patients with community-acquired pneumonia.

METHODS

We studied 496 patients > 14 years of age collected from the study samples of three population-based studies carried out in the same geographical area ("Maresme" region in the Mediterranean coast in Barcelona, Spain) with the same methodology over an 8-year period (1987-1995).

RESULTS

Fifty-six percent of patients were hospitalized and 44% were treated at home. Of the 474 patients with etiological evaluation, 195 patients had an identifiable etiology (overall diagnostic yield 41%). Streptococcus pneumoniae was the most common causative organism. Viral infection was diagnosed in 26.5% of hospitalized patients vs. 13.2% of ambulatory patients (P=0.03). Twenty-five percent of the 68 patients with documented etiology treated at home had Chlamydia pneumoniae infection compared with 14.3% of those treated in the hospital. Ten percent of hospitalized patients had pneumonia caused by two pathogens compared with 9.7% of ambulatory patients. The association of viruses and bacteria was the most frequent cause of dual infection (79% inpatients, 67% outpatients).

CONCLUSIONS

This study has provided information on etiology of community-acquired pneumonia in hospitalized patients and in patients treated at home. A considerable proportion of patients had viral pneumonia, frequently requiring hospital admission for inpatient care.

Community-acquired pneumonia: aetiologic changes in a limited geographic area. An 11-year prospective study

The aim of this study is to describe the changes in the aetiology of hospitalised patients with community-acquired pneumonia (CAP) during an 11-year observational period in a limited geographic area. Eight hundred and one (801) adult patients with CAP hospitalised were included. The patients were divided into three groups according to the time of presentation. Comprehensive microbiological laboratory tests were performed and differences in aetiology were analysed. In 228 patients (31%), a pathogen was detected, with Coxiella burnetii being the most common (20.1%). Significant variations in the prevalence of Chlamydophila pneumoniae were found between groups but not in other pathogens. In conclusion, long-term epidemiological studies may contribute to the knowledge of actual CAP aetiology.

Community-acquired viral pneumonia

Advanced age often is associated with functional and immunologic decline and chronic cardiopulmonary diseases that predispose to pneumonia when viral infection occurs. Influenza virus remains the primary viral pathogen in the elderly, although the impact of the other respiratory viruses remains to be defined. The clinical syndromes associated with respiratory viruses frequently are indistinguishable from one another or bacterial pathogens; often, viral illness in older adults exacerbates underlying conditions, complicating diagnosis. Antiviral therapy is available for influenza A and B; specific viral diagnosis, particularly with the use of rapid antigen detection, may be useful for clinical management. Treatment for other viruses primarily is supportive.

An audit of influenza and pneumococcal vaccination in rheumatology outpatients

Background

Influenza and pneumococcal vaccination are recommended for a number of clinical risk groups including patients treated with major immunosuppressant disease modifying anti-rheumatic drugs. Such immunisation is not only safe but immunogenic in patients with rheumatic diseases. We sought to establish dual vaccination rates and significant influencing factors amongst our hospital rheumatology outpatients.

Method

We audited a sample of 101 patients attending hospital rheumatology outpatient clinics on any form of disease modifying treatment by clinical questionnaire and medical record perusal. Further data were collected from the local immunisation coordinating agency and analysed by logistic regression modelling.

Results

Although there was a high rate of awareness with regard to immunisation, fewer patients on major immunosuppressants were vaccinated than patients with additional clinical risk factors against influenza (53% vs 93%, p < 0.001) or streptococcus pneumoniae (28% vs 64%, p = 0.001). The presence of additional risk factors was confirmed as significant in determining vaccination status by logistic regression for both influenza (OR 10.89, p < 0.001) and streptococcus pneumoniae (OR 4.55, p = 0.002). The diagnosis of rheumatoid arthritis was also found to be a significant factor for pneumococcal vaccination (OR 5.1, p = 0.002). There was a negative trend suggesting that patients on major immunosuppressants are less likely to be immunised against pneumococcal antigen (OR 0.35, p = 0.067).

Conclusion

Influenza and pneumococcal immunisation is suboptimal amongst patients on current immunosuppressant treatments attending rheumatology outpatient clinics. Raising awareness amongst patients may not be sufficient to improve vaccination rates and alternative strategies such as obligatory pneumococcal vaccination prior to treatment initiation and primary care provider education need to be explored.

Treatment of community-acquired pneumonia, with special emphasis on gemifloxacin

Community-acquired pneumonia (CAP) is the cause of substantial morbidity, mortality, and resource utilization worldwide. When choosing an antimicrobial, effective treatment depends on proper patient evaluation and the identification of numerous risk factors, such as recent antibiotic exposure or the presence of comorbidity. Patients without any risk factor should be treated effectively with a narrow spectrum beta-lactam agent, like amoxicillin, or a macrolide. If a risk factor is present, agents with a broader spectrum of activity should be selected for the empirical therapy. The newer-generation quinolones are suitable agents with their excellent in vitro activity and pharmacodynamic-pharmacokinetic properties. They are not only active against susceptible CAP pathogens, but also against the resistant strains. Among the quinolones, gemifloxacin has the best in vitro activity. Its improved bioavailability, pharmacokinetic-pharmacodynamic properties, and safety profile make this agent an excellent option for the treatment of CAP.

Radiological imaging in pneumonia: recent innovations

PURPOSE OF REVIEW

Pneumonia is one of the major infectious diseases responsible for significant morbidity and mortality throughout the world. Radiological imaging plays a prominent role in the evaluation and treatment of patients with pneumonia. This paper reviews recent innovations in the radiologic diagnosis and management of suspected pulmonary infections.

RECENT FINDINGS

Chest radiography is the most commonly used imaging tool in pneumonias because of availability and an excellent cost-benefit ratio. Computed tomography is mandatory in unresolved cases or when complications of pneumonia are suspected. A specific radiologic pattern can suggest a diagnosis in many cases. Bacterial pneumonias are classified into four main groups: community-acquired, aspiration, healthcare-associated and hospital-acquired pneumonia. The radiographic patterns of community-acquired pneumonia may be variable and are often related to the causative agent. Aspiration pneumonia involves the lower lobes with bilateral multicentric opacities. The radiographic patterns of healthcare-associated and hospital-acquired pneumonia are variable, most commonly showing diffuse multifocal involvement and pleural effusion.

SUMMARY

Combination of pattern recognition with knowledge of the clinical setting is the best approach to the radiologic interpretation of pneumonia. Radiological imaging will narrow the differential diagnosis of direct additional diagnostic measures and serve as an ideal tool for follow-up examinations.

Characteristics of low-risk patients hospitalized with community-acquired pneumonia

BACKGROUND

Despite the wide distribution of different severity scoring systems for community-acquired pneumonia (CAP) patients, low-risk patients are frequently hospitalized, contrary to current recommendations. The aim of our study was to determine the rate, clinical characteristics, and outcome of low-risk patients with CAP admitted to our institution.

METHODS

During an 18-month period, we prospectively screened all patients admitted to the Division of Internal Medicine with a presumptive diagnosis of CAP. Pneumonia Outcome Research Team (PORT) score and pneumonia severity index (PSI) were calculated for all patients during the first 24 h.

RESULTS

A total of 591 patients had a diagnosis of CAP. Some 196 patients (33.1%) were low-risk (PSI class I, II), 98 (16.6%) intermediate (PSI III), and 297 (50.3%) high-risk patients (PSI IV, V). Patients in low-risk classes were younger (45.5+/-15.8 vs. 65.0+/-12.5 and 74.9+/-11.8 years, respectively, p<0.001) and had fewer background diseases. They had shorter hospitalizations than intermediate- and high-risk groups (4.4+/-3.2, 5.3+/-3.4, and 6.8+/-6.4 days, respectively, p<0.001). There was a significant difference in 30-day mortality between the different risk groups: 0% in the low-risk, 2.0% in the intermediate-risk, and 9.4% in the high-risk group (p<0.001).

CONCLUSION

The considerable proportion of low-risk patients hospitalized due to CAP was found to be comparable to the stable 30% rate reported in the literature. We conclude that physicians tend to opt for a wide safety range when considering a CAP patient hospitalization, rather than make a decision based only on severity score calculation.

Severe community-acquired pneumonia: approach to therapy

Despite substantial progress in therapeutic options, severe community-acquired pneumonia (CAP) remains a significant cause of morbidity and mortality worldwide. Recognising the clinical importance of CAP over the past several years, different medical societies and health organisations in different countries have proposed specific guidelines for the management of CAP. Early and rapid initiation of antimicrobial therapy has been advocated for a favourable outcome. Treatment is empirical as the diagnostic yield for potential pathogens does not exceed 50%. Dual therapy is emerging as the preferred therapy for severe CAP. The regimen is based on an epidemiological approach with emphasis on covering both typical and atypical pathogens. Non-antimicrobial adjuvant therapies including non-invasive ventilation and immunomodulatory agents are emerging as promising area for future development.

High-throughput amplification fragment length polymorphism (htAFLP) analysis identifies genetic lineage markers but not complement phenotype-specific markers in Moraxella catarrhalis

Comparative high-throughput amplified fragment length polymorphism (htAFLP) analysis was performed on a set of 25 complement-resistant and 23 complement-sensitive isolates of Moraxella catarrhalis in order to determine whether there were complement phenotype-specific markers within this species. The htAFLP analysis used 21 primer-pair combinations, generating 41 364 individual fragments and 2273 fragment length polymorphisms, with an average of 862 polymorphisms per isolate. Analysis of polymorphism data clearly indicated the presence of two phylogenetic lineages and 40 (2%) lineage-specific polymorphisms. However, despite the presence of 361 (16%) statistically significant complement phenotype-associated polymorphisms, no single marker was 100% complement phenotype-specific. Furthermore, no complement phenotype-specific marker was found within different phylogenetic lineages. These findings agree with previous results indicating that the complement resistance phenotype within M. catarrhalis is probably defined by multiple genes, although not all of these genes may be present within all M. catarrhalis isolates.

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.

Community-Acquired Respiratory Complications in the Intensive Care Unit: Pneumonia and Acute Exacerbations of COPD

This chapter will review the two most common lower respiratory tract infections in the intensive care unit (ICU), community-acquired pneumonia (CAP) and acute exacerbations of chronic obstructive pulmonary disease (AECOPD). In addition we will provide an overview of the topics including recommendations for the diagnosis and treatment.

[Follow-up criteria for community acquired pneumonias and acute exacerbations of chronic obstructive pulmonary disease]

The follow-up of Community Acquired Pneumonias (CAP) and Acute Exacerbations of Chronic Obstructive Pulmonary Diseases (AECOPD) differs with the setting of care, but overall calls upon the same investigations as the initial evaluations. In the event of initial ambulatory care, the evaluation is carried out primarily on clinical data, at the 2 or 3rd day for the CAP, at the 2nd to 5th day for the AECOPD. In the event of unfavourable evolution, or from the start in the most severe cases, the follow-up is carried out in hospital; clinical evaluation is readily daily, and all the more frequent that the clinical condition is worrying because of the severity or risk factors. The investigations will be limited to those initially abnormal in the event of favourable evolution; on the contrary, unfavourable evolution can justify new investigations which depend on clinical characteristics. Remotely, i.e. 4 to 8 weeks later, must be checked the return at the baseline clinical state, a chest X-ray (CAP), spirometry and arterial blood gas (AECOPD), even bronchoscopy and thoracic CT-scan.

The role of new therapies for severe community-acquired pneumonia

PURPOSE OF REVIEW

Community-acquired pneumonia (CAP) is associated with significant morbidity and mortality and is the most common cause of death from infectious diseases. CAP patients requiring intensive care unit (ICU) admission carry the highest mortality rates. This paper aims to review the current literature regarding epidemiology, risk factors, severity criteria and reasons for admitting the hospitalized patient to the ICU, and the empiric and specific antibiotic therapeutic regimens employed.

RECENT FINDINGS

Multiple sets of clinical practice guidelines have been published in the past few years addressing the treatment of CAP. The guidelines all agree that CAP patients admitted to the hospital represent a major concern, and appropriate empiric therapy should be instituted to improve clinical outcomes.

SUMMARY

The cost, morbidity and mortality of CAP patients requiring ICU admission remain unacceptably high. These are heterogeneous groups of patients, so it is important to use risk-stratification based on clinical parameters and prediction tools. Appropriate antibiotic therapy is an important component in the management of both groups of patients. In particular, it is essential to administer an appropriate antimicrobial agent from the initiation of therapy, so that the risks of treatment failure and the morbidity of CAP may be minimized.

[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).

Antibiothérapie des pneumonies aiguës communautaires à Streptococcus pneumoniae : impact clinique de la résistance bactérienne

The emergence of Streptococcus pneumoniae strains with reduced susceptibility to beta-lactams and with multiple drug resistance has not led to major changes in recommendations for antibiotic therapy in patients with acute community-acquired pneumococcal pneumonia. Numerous factors explain the limited clinical impact of this major microbiological change. The frequency of intermediate strains is high but the frequency of resistant strains to beta-lactams is very low. There is a complex relation between the acquisition of resistance to beta-lactams and the decreased virulence of S. pneumoniae strains. The only finding in studies of humanized experimental animal models of lethal bacteremic pneumonia caused by resistance and tolerant strains was a slowing in the kinetics of beta-lactams bactericidal activity, especially for amoxicillin. Taken together, this preclinical data shows that microbiological resistance of pneumococci to beta-lactams has very little influence on a possible failure of recommanded treatment regimens for pneumococcal pneumonia. The high rate of multiple drug resistance, particularly among beta-lactam resistant strains, rules out the probabilistic use of macrolides. Conversely, fluoroquinolone (FQ) resistance remains low, inferior to 3%, and the same is true for ketolides (<1%). Only a global strategy of patient management in the use of these new drugs could ensure their long-term activity. The high mortality rate of hospitalized S. pneumoniae pneumonia will only be improved with a better understanding of the complex host-bacteria interactions.

Outbreak of Chlamydia pneumoniae infection in a Japanese nursing home, 1999-2000

OBJECTIVE

To identify risk factors for infection and severe illness due to Chlamydia pneumoniae.

METHODS

To identify risk factors for infection, we conducted a case-control study among nursing home residents who had onset of symptoms during December 1, 1999, to February 20, 2000. To identify risk factors for severe illness among nursing home residents, we conducted a retrospective cohort study.

SETTING

A nursing home providing long-term and day care services for elderly patients in Japan.Participants. Fifty-nine residents and 41 staff members of a nursing home.

RESULTS

The attack rates for respiratory illness were 53% (31 of 59) among residents and 22% (9 of 41) among staff. Infection was confirmed in 15 resident and 2 staff case patients by isolation of C. pneumoniae from nasal swab specimens. Fifteen resident case patients developed severe illness (ie, bronchitis, pneumonia, and hypoxia); one case patient died. The median age of resident case patients was 87 years. We could identify neither the source of the outbreak nor significant risk factors for infection and severe illness in residents. However, residents with a higher level of physical activity were more likely to become infected, whereas older residents (aged more than 85 years) and those with a lower level of physical activity were more likely to develop severe illness (P>.05). Contact with residents was a risk factor for infection in staff (relative risk, undefined; P=.04).

CONCLUSIONS

C. pneumoniae can cause large outbreaks of infection and severe illness among elderly persons, and its transmission is likely to be enhanced by close contacts among people in nursing homes. Therefore, early detection of an outbreak by means of better surveillance, and subsequent isolation of patients, may be effective control measures.

Assessment of analysis of urinary pneumococcal antigen by immunochromatography for etiologic diagnosis of community-acquired pneumonia in adults

The limitations of conventional microbiologic methods (CMM) for etiologic diagnosis of community pneumococcal pneumonia have made faster diagnostic techniques necessary. Our aim was to evaluate the usefulness of the immunochromatography (ICT) technique for detecting urinary Streptococcus pneumoniae antigen in the etiologic diagnosis of community-acquired pneumonias (CAP). This was a prospective study on in-patients with CAP in a tertiary hospital conducted from October 2000 to March 2004. Apart from using CMM to reach an etiologic diagnosis, we determined pneumococcal antigen in concentrated urine by ICT. We also determined the urinary pneumococcal antigen (UPA) content in patients from two control groups to calculate the specificity of the technique. One group was comprised of in-patients diagnosed with chronic obstructive pulmonary disease (COPD) or asthma, with respiratory infection, and without pneumonia; the other group included fractures. We studied 959 pneumonia patients and determined UPA content in 911 (95%) of them. We diagnosed the etiology of 253 cases (28%) using CMM; S. pneumoniae was the most common etiologic agent (57 cases). ICT analysis was positive for 279 patients (31%). Using this technique, the percentage of diagnoses of pneumococcal pneumonias increased by 26%, while the overall etiologic diagnosis increased from 28 to 49%. The technique sensitivity was 81%; the specificity oscillated between 80% in CAP with nonpneumococcal etiology and 99% for patients with fractures without infections. Determination of UPA is a rapid, simple analysis with good sensitivity and specificity, which increased the percentage of etiologic diagnoses. Positive UPA may persist in COPD patients with probable pneumococcal colonization or recent pneumococcal infections.

Reasons for coming to hospital after treatment for community-acquired pneumonia on an ambulatory basis

BACKGROUND

Most patients with community-acquired pneumonia (CAP) are treated on an ambulatory basis.

OBJECTIVE

To evaluate the reasons for presentation to hospital after treatment for CAP on an ambulatory basis.

METHODS

The study, conducted in five hospitals in the Capital Health Region (Edmonton, Alberta), enrolled adult patients aged 17 years or older who presented with a history of having been diagnosed and treated for pneumonia within the previous month. A current diagnosis of pneumonia was based on two or more symptoms or signs of CAP, plus radiographic evidence of pneumonia.

RESULTS

Seventy-five (77.3%) of the 97 patients who met the inclusion criteria had CAP, and 22 (22.7%) patients presented with a noninfectious illness. Of the patients with CAP, 25 (33.3%) met the study criteria for worsening of a comorbid illness, 23 (30.7%) had clinical failure, 16 (21.3%) had microbiological failure, six (8.0%) were noncompliant, four (5.3%) had failure of expectations and one (1.3%) had adverse effects of antimicrobial therapy.

CONCLUSIONS

Underlying diseases, exacerbations of comorbidities and complications of CAP, as well as confounders such as unusual infections and noninfectious conditions that mimic CAP, are all reasons for presenting to hospital after treatment for CAP in an ambulatory setting.

Low prevalence of Chlamydia pneumoniae in adults with community-acquired pneumonia

The incidence of community-acquired pneumonia (CAP) due to Chlamydia pneumoniae was determined in a prospective study of 546 adult patients with CAP included in the German CAP Competence Network (CAPNETZ) project. Three different PCR protocols for detection of C. pneumoniae in respiratory specimens were compared by a multicenter, inter-laboratory comparison involving three laboratories. A case was defined as a patient with a respiratory sample positive by PCR in at least two laboratories. CAP was caused by C. pneumoniae in 5/546 cases (0.9%). Antibody testing by microimmunofluorescence was done in 376 of 546 patients. All patients were negative for IgM antibodies. In the five PCR-positive patients, neither specific IgG nor IgA antibodies were found. Patients with CAP caused by C. pneumoniae had a lower median age (36 years) than the general study population (62 years). C. pneumoniae is currently a rare cause of CAP in adult patients in Germany. Analysis of a single serum sample is not useful for diagnosis of acute C. pneumoniae infection in CAP.

[Definition of low respiratory tract infections]

Lower respiratory tract infection is easily suggested on clinical signs (cough and sputum) associated with fever. To discriminate between pneumonia and acute bronchitis is crucial because of the mortality associated with pneumonia and of its specific management. Chest X-ray is a key exam for the diagnosis and should be performed on the basis of validated clinical signs that are however of weak diagnostic value. Clinical as well as radiological signs cannot be reliably used to identify the causative germ. Sputum examination, the search for pneumococcal and legionella urinary antigens are of good diagnostic value. An associated COPD may lead to an acute respiratory failure. Acute exacerbation of chronic bronchitis results from various causes but infection is involved in about 50% of the cases, mostly viral and most often due to a rhinovirus. Viral infection can be associated to bacterial infection and the most frequently isolated germs are Streptococcus pneumoniae, Haemophilus influenzae, and B. catarrhalis. Severity assessment relies on the value of basal FEV1 that is often non available. Therefore Afssaps suggests using a dyspnea index to assess exacerbation severity.

Haemophilus Influenzae contributes to morbidity but not mortality in severely burned patients

Due to a successful Haemophilus Influenzae (HIF) vaccination program, this pathogen is no longer a major contributor to childhood morbidity and mortality. The effect on adult acquisition of HIF is unknown. The purpose of this study was to determine HIF infection frequency in severely burned patients. In a 62-month period, there were 1486 admissions. Twenty-four of 1,486 (1.6%) burn patients had HIF pneumonia: 16 (1%) within 72 h after injury; 8 (0.5%) patients developed it after the seventh day of hospitalization; 74 of 1,486 (5.0%) burn patients had pneumonia due to other organisms. There was no statistically significant difference between patients with HIF pneumonia and those with other pathogens with respect to age, race, sex, percent total body surface area (TBSA), inhalation injury, ventilator days, intensive care days, sepsis, or mortality. Nineteen percent of patients with HIF were<14 years of age compared to 12% in the other pneumonia group, p<0.01. HIF contributed to both an early and late pneumonia in burn patients. The organism responded to treatment and did not affect mortality.

Modelling hospital admissions for lower respiratory tract infections in the elderly in England

Despite the importance of lower respiratory-tract infection (LRI) in causing hospitalizations in elderly patients (>or=65 years of age) and recent advances in vaccine development, a complete picture of the causative organisms is not available. All hospital discharge diagnoses (ICD-10 code) for LRI in elderly patients in England during 1995-1998 were reviewed. Using known seasonality in potential causative agents of LRI, the contribution of different respiratory pathogens to hospitalizations coded as 'unspecified LRI' was estimated by multiple linear regression analysis. Ninety-seven per cent of 551633 LRI-associated diagnoses had no specific organism recorded. From the statistical model the estimated proportions of admissions attributable to different pathogens were applied to calculate estimated hospitalization rates: 93.9 hospitalizations/10000 population aged >or=65 years due to S. pneumoniae, 22.9 to influenza virus, 22.3 to H. influenzae, 17.0 to whooping cough, and 12.8 to respiratory syncytial virus. There is enormous potential to improve health using existing vaccines and those under development.

Immunization with the iron uptake ABC transporter proteins PiaA and PiuA prevents respiratory infection with Streptococcus pneumoniae

Previous studies show that vaccination with the recombinant Streptococcus pneumoniae lipoproteins PiuA and PiaA protects mice against systemic S. pneumoniae disease. The aim of this study was to assess the level of conservation of PiaA and PiuA and a third iron uptake ABC transporter lipoprotein, PitA, between common S. pneumoniae capsular serotypes by sequencing the corresponding genes, and to investigate whether these antigens can protect against respiratory infection. The nucleotide sequences of piuA and piaA were highly conserved in all strains, whereas pitA had significant variation in its nucleotide sequence making PitA an unattractive vaccine candidate. Mucosal vaccination of mice with PiuA and PiaA elicited specific antibody responses in serum and respiratory secretions, and protected against intranasal challenge with S. pneumoniae. These results provide further data indicating that PiuA and PiaA would be suitable candidates for a S. pneumoniae protein antigen vaccine.

Evaluating the Use of a Streptococcus pneumoniae Urinary Antigen Detection Kit for the Management of Community-Acquired Pneumonia in Japan

BACKGROUND

The urinary antigen detection kit for Streptococcus pneumoniae was tested.

OBJECTIVES

It was our aim to evaluate the usefulness of the immunochromatographic membrane test by doing a large prospective study of community-acquired pneumonia (CAP) in Japan.

METHODS

We prospectively evaluated the use of the S. pneumoniae urinary antigen detection kit and analyzed the treatment and clinical effect seen in patients with positive test kit results. One hundred and fifty-six patients with CAP admitted to our hospital between October 2001 and September 2003 were evaluated.

RESULTS

In 49% of these CAP patients, the causative microorganisms were isolated. S. pneumoniae was suspected to be the causative microorganism in 15%, but positive results of the urinary antigen detection kit indicated S. pneumoniae to be a probable microorganism in 28%, even though antibiotics had previously been administered to half of the patients. The kit was particularly useful for diagnosing patients with poor quality sputum in whom antibiotics treatment nevertheless had to be selected. Antibiotics appropriate for S. pneumoniae (mainly penicillin) were given. The treatment was found to have excellent clinical results in 89% of the CAP patients.

CONCLUSIONS

The S. pneumoniae urinary antigen detection kit was considered to be useful in selecting treatment since there was a high level of clinical effectiveness when the most suitable antibiotics were immediately administered to positive patients. The use of the S. pneumoniae urinary antigen kit is rapid and simple compared with conventional microbiological procedures.

Isolated central nervous system histoplasmosis in immunocompetent hosts: a series of 11 cases

Histoplasmosis of the central nervous system occurs in a significant percentage of patients with Histoplasma capsulatum infection, but has usually been described in association with immunosuppression and/or disseminated histoplasmosis. We aim to review the clinical and laboratory features of isolated histoplasmosis of the central nervous system in the immunocompetent host by presenting a series of 11 cases with this condition. Most of these patients presented with headache, meningeal irritation signs and mental status changes, comprising a somewhat different picture from that described in immunosuppressed patients. Moreover, almost all patients had signs of ventricular dilatation in neuroimaging studies, and 8 of the 11 patients had a ventriculoperitoneal shunt at the time of diagnosis, suggesting hydrocephalus to be an important feature of this condition and/or the possibility of shunt infection by the fungus. Immunodiffusion analysis of the cerebrospinal fluid appeared to be the most efficient way to reach the diagnosis and should be considered in immunocompetent patients with chronic lymphocytic meningitis, especially in those who have ventricular shunt or live in endemic areas of Histoplasma capsulatum.

Analysis of factors that contribute to treatment failure in patients with community-acquired pneumonia

To determine the causes of treatment failure and to evaluate the prognostic factors in patients hospitalized for community-acquired pneumonia, a prospective, observational study of 228 adult patients hospitalized for a community-acquired pneumonia in the University Hospital of Geneva and the La Chaux-de-Fonds Community Hospital, Switzerland, was conducted. The percentage of patients who failed to improve (as defined by guidelines of the Infectious Disease Society of America) and the causes of treatment failure were assessed, and patients who failed to improve under antimicrobial therapy were compared with those who did improve. In the 54 (24%) patients who failed to improve, a mean increase in length of hospitalization of 4 days was observed. Most causes of treatment failure could be attributed to host factors (61%) rather than to the pathogen (16%) or to an inappropriate antibiotic regimen (3%). After adjusting for potentially confounding variables, concomitant neoplasia (OR 3.25; 95%CI 1.11-9.56), neurological disease (OR 2.34; 95%CI 1.07-5.13), and aspiration pneumonia (OR 2.97; 95%CI 29-6.86]) were associated with failure to improve, whereas monocytosis improved prognosis (OR 0.40; 95%CI 0.20-0.80). Almost one out of four patients hospitalized for community-acquired pneumonia failed to respond to empirical antibiotic treatment. Aspiration pneumonia, concomitant neoplasia, and neurological disease were factors positively associated with failure to improve, whereas monocytosis was linked to a better prognosis.

Involvement of potD in Streptococcus pneumoniae polyamine transport and pathogenesis

Polyamines such as putrescine, spermidine, and cadaverine are small, polycationic molecules that are required for optimal growth in all cells. The intracellular concentrations of these molecules are maintained by de novo synthesis and transport pathways. The human pathogen Streptococcus pneumoniae possesses a putative polyamine transporter (pot) operon that consists of the four pot-specific genes potABCD. The studies presented here examined the involvement of potD in polyamine transport and in pneumococcal pathogenesis. A potD-deficient mutant was created in the mouse-virulent serotype 3 strain WU2 by insertion duplication mutagenesis. The growth of the WU2DeltapotD mutant was identical to that of the wild-type strain WU2 in vitro in rich media. However, WU2DeltapotD possessed severely delayed growth compared to wild-type WU2 in the presence of the polyamine biosynthesis inhibitors DFMO (alpha-dimethyl-fluoroornitithine) and MGBG [methylgloxal-bis (guanyl hydrazone)]. The mutant strain also showed a significant attenuation in virulence within murine models of systemic and pulmonary infection regardless of the inoculation route or location. These data suggest that potD is involved in pneumococcal polyamine transport and is important for pathogenesis within various infection models.