Aetiology of community-acquired pneumonia: a prospective study among adults requiring admission to hospital

Acute organ injury and long-term sequelae of severe pneumococcal infections

Streptococcus pneumoniae (Spn) is a major public health problem, as it is a main cause of otitis media, community-acquired pneumonia, bacteremia, sepsis, and meningitis. Acute episodes of pneumococcal disease have been demonstrated to cause organ damage with lingering negative consequences. Cytotoxic products released by the bacterium, biomechanical and physiological stress resulting from infection, and the corresponding inflammatory response together contribute to organ damage accrued during infection. The collective result of this damage can be acutely life-threatening, but among survivors, it also contributes to the long-lasting sequelae of pneumococcal disease. These include the development of new morbidities or exacerbation of pre-existing conditions such as COPD, heart disease, and neurological impairments. Currently, pneumonia is ranked as the 9^th leading cause of death, but this estimate only considers short-term mortality and likely underestimates the true long-term impact of disease. Herein, we review the data that indicates damage incurred during acute pneumococcal infection can result in long-term sequelae which reduces quality of life and life expectancy among pneumococcal disease survivors.

Outcomes and Predictors of Severe Community-acquired Pneumonia Among Adults Admitted to the University of Gondar Comprehensive Specialized Hospital: A Prospective Follow-up Study

Background

Severe community-acquired pneumonia is a common life-threatening infection with a high rate of unfavorable outcome. This study aimed to assess the outcomes and predictors of hospitalized severe community-acquired pneumonia patients at University of Gondar comprehensive specialized hospital.

Methods

A prospective follow-up study was conducted at University of Gondar comprehensive specialized hospital from May 1 to September 31, 2021. The data was collected by reviewing patients' charts and interviewing the patients themselves. Descriptive statistics, binary and multivariable logistic regression analysis were performed accordingly. Variables with p-value <0.2 on binary logistic regression were analyzed using multivariable logistic regression and variables with p<0.05 were considered to have significant association.

Results

A total of 239 admitted patients with severe community-acquired pneumonia were enrolled in the study. An unfavorable outcome was observed in 105 (44%) patients; 24.27% was in-hospital all-cause mortality, 12.5% was nonresolution, 5.8% was complicated cases, and 1.26% were gone against medical care for poor prognosis. After analyzing multivariable logistic regression, confusion (OR= 4.84; 95%CI: 1.47-15.88), anemia (OR= 2.36; 95%CI: 1.01-5.52), leukopenia (OR=4.38; 95%CI: 1.26-15.25), leukocytosis (OR=3.15; 95%CI: 1.23-7.96), elevated creatinine (OR=5.67; 95%CI: 1.72-18.65), intubation (OR=7.27; 95%CI: 1.58-33.37) and antibiotic revision during treatment for a different reason (OR=0.02; 95%CI: 0.01-0.07) were variables significantly associated with unfavorable outcome.

Conclusion

Unfavorable outcome was high among hospitalized severe community acquired pneumonia patients, and confusion, elevated creatinine, anemia, leukopenia, leukocytosis, intubation during admission, and antibiotic revision during the course were independent predictors associated significantly with the unfavorable outcome. It is important to consider the development of a treatment protocol for the hospital and to further research incorporating the microbiologic profile of the patients.

Pneumonia, Aspiration Pneumonia, or Frailty-Associated Pneumonia?

Pneumonia is a common reason for admission afflicting frail older adults. Those who are the frailest are more likely to be provided with a diagnosis of aspiration pneumonia. This diagnosis has no clear definition and no clinical consensus. It is therefore time to stop attempting to differentiate between pneumonia type and use the term frailty-associated pneumonia.

The expansive effects of polyamines on the metabolism and virulence of Streptococcus pneumoniae

Polyamines are common intracellular metabolites of nearly all cells, and their conservation across a vast diversity of cells suggests critical roles for these compounds in cellular physiology. Most intracellular polyamines are associated with RNA and, subsequently, polyamines have significant effects on transcription and translation. Putrescine and spermidine are the most common polyamines in bacteria. Intracellular polyamine pools in bacteria are tightly controlled by both de novo synthesis and transport. Polyamine homeostasis is emerging as a critical parameter of multiple pathways and physiology with substantial impact on bacterial pathogenesis, including the important human pathogen Streptococcus pneumoniae. Modulation of polyamine metabolism in pneumococci is an important regulator of central metabolism. It has broad effects on virulence factors such as capsule as well as stress responses that ultimately impact the survival of pneumococcus in a host. Polyamine transport protein as a single antigen or in combination with other pneumococcal proteins is shown to be an efficacious immunogen that protects against nasopharyngeal colonization, and invasive disease. A comprehensive description of polyamine metabolic pathways and their intersection with pneumococcal pathogenesis will undoubtedly point to novel approaches for treatment and prevention of pneumococcal disease.

A high C-reactive protein/procalcitonin ratio predicts Mycoplasma pneumoniae infection

Background Discriminating Mycoplasma pneumoniae (MP) from Streptococcus pneumoniae (SP) and viral etiologies of community-acquired pneumonia (CAP) is challenging but has important implications regarding empiric antibiotic therapy. We investigated patient parameters upon hospital admission to predict MP infection. Methods All patients hospitalized in a tertiary care hospital between 2013 and 2017 for CAP with a confirmed etiology were analyzed using logistic regression analyses and area under the receiver operator characteristics (ROC) curves (AUC) for associations between demographic, clinical and laboratory features and the causative pathogen. Results We analyzed 568 patients with CAP, including 47 (8%) with MP; 152 (27%) with SP and 369 (65%) with influenza or other viruses. Comparing MP and SP by multivariate logistic regression analysis, younger age (odds ration [OR] 0.56 per 10 years, 95% CI 0.42-0.73), a lower neutrophil/lymphocyte ratio (OR 0.9, 0.82-0.99) and an elevated C-reactive protein/procalcitonin (CRP/PCT) ratio (OR 15.04 [5.23-43.26] for a 400 mg/μg cut-off) independently predicted MP. With a ROC curve AUC of 0.91 (0.80 for the >400 mg/μg cutoff), the CRP/PCT ratio was the strongest predictor of MP vs. SP. The discriminatory value resulted from significantly lower PCT values (p < 0.001) for MP, while CRP was high in both groups (p = 0.057). Comparing MP and viral infections showed similar results with again the CRP/PCT ratio providing the best information (AUC 0.83; OR 5.55 for the >400 mg/μg cutoff, 2.26-13.64). Conclusions In patients hospitalized with CAP, a high admission CRP/PCT ratio predicts M. pneumoniae infection and may improve empiric management.

Where is Chlamydophila pneumoniae pneumonia?

BACKGROUND

Molecular diagnostic methods have recently gained widespread use, and consequently, the importance of viral pathogens in community-acquired pneumonia (CAP) has undergone re-evaluation. Under these circumstances, the role of Chlamydophila pneumoniae as a pathogen that causes CAP also needs to be reviewed.

METHODS

We reviewed articles that contained data on the frequency of identification of C. pneumoniae pneumonia as a causative pathogen for CAP. The articles were identified by performing a search in PubMed with the keywords "community-acquired pneumonia" and "pathogen".

RESULTS

Sixty-three articles were identified. The reviewed articles demonstrated that the rates of identification of C. pneumoniae as the causative pathogen for CAP were significantly lower in assessments based on polymerase chain reaction (PCR) methods than in those based on serological methods. In some studies, it was possible to compare both serological and PCR methods directly using the same set of samples.

CONCLUSIONS

The use of PCR methods, including multiplex PCR assays, has revealed that C. pneumoniae may play a limited role as a pathogen for CAP.

Evolving Understanding of the Causes of Pneumonia in Adults, With Special Attention to the Role of Pneumococcus

Before 1945, Streptococcus pneumoniae caused more than 90% of cases of pneumonia in adults. After 1950, the proportion of pneumonia caused by pneumococcus began to decline. Pneumococcus has continued to decline; at present, this organism is identified in fewer than fewer10%-15% of cases. This proportion is higher in Europe, a finding likely related to differences in vaccination practices and smoking. Gram-negative bacilli, Staphylococcus aureus, Chlamydia, Mycoplasma, and Legionella are each identified in 2%-5% of patients with pneumonia who require hospitalization. Viruses are found in 25% of patients, up to one-third of these have bacterial coinfection. Recent studies fail to identify a causative organism in more than 50% of cases, which remains the most important challenge to understanding lower respiratory infection. Our findings have important implications for antibiotic stewardship and should be considered as new policies for empiric pneumonia management are developed.

Are third-generation cephalosporins unavoidable for empirical therapy of community-acquired pneumonia in adult patients who require ICU admission? A retrospective study

BACKGROUND

Third-generation cephalosporins (3GCs) are recommended for empirical antibiotic therapy of community-acquired pneumonia (CAP) in patients requiring ICU admission. However, their extensive use could promote the emergence of extended-spectrum beta-lactamases-producing Enterobacteriaceae. Our aim was to assess whether the use of 3GCs in patients with CAP requiring ICU admission was justified.

METHODS

We assessed all patients with CAP who required ICU admission during a 7-year period. We recorded empirical and definitive antibiotic therapies and susceptibility of causative pathogens. Amoxicillin, amoxicillin/clavulanate (A/C) susceptibilities as well as amikacin susceptibility of A/C-resistant strains were recorded.

RESULTS

From January 2007 to March 2014, 391 patients were included in the study. Empirical 3GCs were used in 215 patients (55%). Among 267 patients with microbiologically documented CAP (68%), 241 received a beta-lactam as definitive therapy, and of those, 3CGs were chosen for 43 patients (18%). Amoxicillin or A/C was active against isolated pathogens in 159 patients (66%), while 39 patients (16%) required a beta-lactam with a broader spectrum than 3GCs. Ninety-four per cent of A/C-resistant strains were amikacin susceptible.

CONCLUSIONS

In ICU patients with CAP, 3GCs given on an empirical basis are changed, according to microbiological documentation, for another beta-lactam in 82% of cases especially to A/C in the absence of resistance risk factor. In patients evidencing risk factors for A/C-resistant strains infection, 3GCs or antipseudomonal beta-lactams including carbapenem associated with amikacin in the most severe patients seem a relevant empirical antibiotic therapy. This strategy could decrease 3GCs' use.

Predictive factors of true bacteremia and the clinical utility of blood cultures as a prognostic tool in patients with community-onset pneumonia

Although blood cultures (BCs) are an important component of diagnostic practice for antibiotic management in patients with pneumonia, several studies have questioned whether they should be performed. The objective of this study was to evaluate the predictive factors of bacteremia and the role of BCs in patients with community-onset pneumonia (community-acquired pneumonia and healthcare-associated pneumonia).This study was retrospectively conducted in patients with community-onset pneumonia who were hospitalized at Jeju National University Hospital between January 2012 and December 2014. A true bacteremia (TB) group and a contaminants or negative bacteremia (CNB) group were classified according to the bacterial growth on the BC media and were investigated for the clinical relevance of the BCs.We enrolled 785 patients; the TB group and the CNB group contained 36 patients (4.5%) and 749 (95.4%) patients, respectively. Only 10 patients (1.2%) required a change in antibiotic therapy based on the BC results (3 patients with an escalation, 7 with a de-escalation). There was no significant difference between the community-acquired pneumonia and the healthcare-associated pneumonia groups with regard to the rate of antibiotic change due to the BC results (1.1% vs 1.4%; P = 0.751). Chronic liver disease (odds ratio [OR] 2.973, 95% confidence interval [CI] 1.099-8.037), a confusion, urea, respiratory rate, blood pressure, age ≥65 (CURB-65) score of 4 to 5 points (OR 3.484, 95% CI 1.304-9.307), and Pneumonia Severity Index (PSI) class V (OR 2.405, 95% CI 1.007-5.743) were independently associated with TB. In patients with PSI class V and a CURB-65 score of 4 to 5 points, the TB group tended to show a higher inhospital mortality rate than the CNB group (50.0% vs 29.4%; P = 0.060, 60.0% vs 42.5%; P = 0.480). The areas under the curve for PSI score and CURB-65 score for predicting TB revealed an increased tendency compared with that of C-reactive protein (0.72, 95% CI 0.630-0.809; and 0.72, 95% CI 0.622-0.819 vs 0.629, 95% CI 0.522-0.735, respectively).It seemed reasonable to selectively conduct BC in patients hospitalized with severe community-onset pneumonia based upon its low overall positive rate, its effects on antimicrobial modification, and the associations of TB with the severity indices of pneumonia.

Impact of pneumococcal conjugate vaccination: a retrospective study of hospitalization for pneumonia in North-East Italy

INTRODUCTION

Pneumonia remains a common reason for hospitalizing infants and the elderly worldwide, and streptococcal infection is often responsible. The aim of this study was to assess the burden of pneumonia in a large general population.

METHODS

All pneumonia-related hospitalizations from 2004 to 2013 in north-east Italy were identified from the hospital records with a first-listed diagnosis on discharge of bacterial pneumonia, or a first-listed diagnosis on discharge of meningitis, septicemia or empyema associated with a secondary diagnosis of bacterial pneumonia. We identified major comorbidities, calculated agespecific case-fatality rates (CFR), and estimated the related cost to the health care system.

RESULTS

Of the 125,722 hospitalizations identified, 96.9% were cases of pneumonia, 2.4% of septicemia, 0.4% of meningitis, and 0.3% of empyema; 75.3% of hospitalizations involved ≥ 65-yearolds. The overall CFR was 12.4%, and it increased with age, peaking in people over 80 (19.6%). The mean annual pneumonia-associated hospitalization rate was 204.6 per 100,000 population, and it peaked in 0- to 4-year-old children (325.6 per 100,000 in males, 288.9 per 100,000 in females), and adults over 65 (844.9 per 100,000 in males, 605.7 per 100,000 in females). Hospitalization rates dropped over the years for the 0-4 year-olds, and rose for people over 80. The estimated overall annual cost of these pneumonia-related hospitalizations was approximately € 41 million.

CONCLUSIONS

This study shows that the burden on resources for pneumonia-related hospitalization is an important public health issue. Prevention remains the most valuable tool for containing pneumonia, and vaccination strategies can help in the primary prevention of infection, possibly reducing the number of cases in all age groups.

Mechanisms and impact of genetic recombination in the evolution of Streptococcus pneumoniae

Streptococcus pneumoniae (the pneumococcus) is a highly recombinogenic bacterium responsible for a high burden of human disease globally. Genetic recombination, a process in which exogenous DNA is acquired and incorporated into its genome, is a key evolutionary mechanism employed by the pneumococcus to rapidly adapt to selective pressures. The rate at which the pneumococcus acquires genetic variation through recombination is much higher than the rate at which the organism acquires variation through spontaneous mutations. This higher rate of variation allows the pneumococcus to circumvent the host innate and adaptive immune responses, escape clinical interventions, including antibiotic therapy and vaccine introduction. The rapid influx of whole genome sequence (WGS) data and the advent of novel analysis methods and powerful computational tools for population genetics and evolution studies has transformed our understanding of how genetic recombination drives pneumococcal adaptation and evolution. Here we discuss how genetic recombination has impacted upon the evolution of the pneumococcus.

Aetiology and risk factors of community-acquired pneumonia in hospitalized patients in Norway

BACKGROUND AND AIMS

In Norway, data on the aetiology of community-acquired pneumonia (CAP) in hospitalized patients are limited. The aims of this study were to investigate the bacterial aetiology of CAP in hospitalized patients in Norway, risk factors for CAP and possible differences in risk factors between patients with Legionnaire's disease and pneumonia because of other causes.

METHODS

Adult patients with radiologically confirmed CAP admitted to hospital were eligible for the study. Routine aerobic and Legionella culture of sputum, blood culture, urinary antigen test for Legionella pneumophila and Streptococcus pneumoniae, polymerase chain reaction detection of Chlamydophila pneumoniae, Mycoplasma pneumoniae and Bordetella pertussis from throat specimens, and serology for L. pneumophila serogroup 1-6 were performed. A questionnaire, which included demographic and clinical data, risk factors and treatment, was completed.

RESULTS

We included 374 patients through a 20-month study period in 2007-2008. The aetiological agent was detected in 37% of cases. S. pneumoniae (20%) was the most prevalent agent, followed by Haemophilus influenzae (6%) and Legionella spp. (6%). Eight Legionella cases were diagnosed by urinary antigen test, of which four also had positive serology. In addition, 13 Legionella cases were diagnosed by serology. The degree of comorbidity was high. An increased risk of hospital-diagnosed Legionella pneumonia was found among patients with a diagnosis of chronic congestive heart failure.

CONCLUSION

Our results indicate that S. pneumoniae is the most common bacterial cause of pneumonia in hospitalized patients, and the prevalence of Legionella pneumonia is probably higher in Norway than recognized previously.

Characterization of the extent of a large outbreak of Legionnaires' disease by serological assays

BACKGROUND

In May 2005, a long-distance outbreak of Legionnaires' disease (LD) caused by Legionella pneumophila serogroup 1 occurred in south-east Norway. The initial outbreak investigation without serology identified 56 laboratory-confirmed LD cases of whom 10 died. However, 116 patients with community-acquired pneumonia might belong to the outbreak based on epidemiological investigations, but acute laboratory tests other than serology were negative or not performed. To assess the true extent of the outbreak, we evaluated two serological assays in order to reclassify the 116 patients with indeterminate case status.

METHODS

Two polyvalent antibody tests, a serogroup 1-6 immunofluorescence assay (IFA) and a serogroup 1-7 enzyme-linked immunosorbent assay (ELISA) were used. They were evaluated with cases defined as culture- or urinary antigen positive LD patients (n=40) and non-cases defined as confirmed non-LD patients (n=39) and healthy control subjects (n=62). The 116 patients, who were negative in culture, polymerase chain reaction and/or urinary antigen tests, were analysed by the same serological assays. Antibodies to the outbreak strain were determined by immunoblotting.

RESULTS

In the evaluation study, the sensitivity and specificity of a ≥4-fold IFA titre change was 38% and 100%, respectively, with corresponding values of 30% and 99% for seroconversion in ELISA. A single high positive IFA titre yielded sensitivity and specificity of 73% and 97%, respectively, with corresponding values of 68% and 96% for a single high immunoglobulin (Ig) G and/or IgM in ELISA. Based on this evaluation, the following serological testing identified 47 more LD cases, and the outbreak thus comprised 103 cases with a case fatality rate of 10%. About the same proportion (70%) of the urinary antigen positive and negative LD cases had antibodies to the serogroup-specific lipopolysaccharide of the outbreak strain. In addition to the 103 LD cases, Legionella infection could not be verified or excluded in 32 patients based on epidemiology and/or lack of microbiological sampling.

CONCLUSIONS

The acute-phase tests (culture, polymerase chain reaction, and urinary antigen) identified less than 55% of the 103 patients in this outbreak. Serological testing thus remains an important supplement for diagnosis of LD and for determination of outbreak cases.

Effects of holding time and measurement error on culturing Legionella in environmental water samples

Outbreaks of Legionnaires' disease require environmental testing of water samples from potentially implicated building water systems to identify the source of exposure. A previous study reports a large impact on Legionella sample results due to shipping and delays in sample processing. Specifically, this same study, without accounting for measurement error, reports more than half of shipped samples tested had Legionella levels that arbitrarily changed up or down by one or more logs, and the authors attribute this result to shipping time. Accordingly, we conducted a study to determine the effects of sample holding/shipping time on Legionella sample results while taking into account measurement error, which has previously not been addressed. We analyzed 159 samples, each split into 16 aliquots, of which one-half (8) were processed promptly after collection. The remaining half (8) were processed the following day to assess impact of holding/shipping time. A total of 2544 samples were analyzed including replicates. After accounting for inherent measurement error, we found that the effect of holding time on observed Legionella counts was small and should have no practical impact on interpretation of results. Holding samples increased the root mean squared error by only about 3-8%. Notably, for only one of 159 samples, did the average of the 8 replicate counts change by 1 log. Thus, our findings do not support the hypothesis of frequent, significant (≥= 1 log10 unit) Legionella colony count changes due to holding.

Pneumococcal pneumonia: differences according to blood culture results

BACKGROUND

Bacteremia by Streptococcus pneumoniae has been traditionally associated with poor outcomes in patients with pneumonia; however, data on its impact on outcomes are limited and are sometimes contradictory.

METHODS

We performed a prospective study in two hospitals in northern Spain in which cases diagnosed with pneumococcal pneumonia were selected from a cohort of hospitalized patients with pneumonia between January 2001 and July 2009. We compared patients with pneumococcal bacteremic pneumonia with those with pneumococcal non-bacteremic pneumonia.

RESULTS

We compared 492 patients with negative blood culture and 399 with positive culture results. Host related factors were very similar in both groups. Severity of illness on admission measured by CURB-65 score was similar in both groups. Adjusted analysis showed a greater likelihood of septic shock during in-hospital course among patients with pneumococcal bacteremia (OR, 2.1; 95% CI, 1.2-3.5; P=0.006). Likewise, patients with positive blood culture had greater in-hospital mortality (OR 2.1; 95% CI, 1.1- -3.9; P=0.02), 15-day mortality (OR 3.6; 95% CI, 1.7-7.4; P=0.0006), and 30-day mortality (OR, 2.7; 95% CI, 1.5-5; P=0.002).

CONCLUSIONS

Although host related factors and severity on admission were very similar in the two groups, bacteremic patients had worse in-hospital course and outcomes. Bacteraemia in pneumococcal pneumonia is of prognostic significance.

Pneumonia as the most common lower respiratory tract infection

Introduction:

Pneumonia is the most serious inflammatory disease of the respiratory system and also the most common infectious disease. Even now, in the 21^st century, pneumonia occupies a prominent place in clinical medicine and public health. We are confronted daily with the increased number of patients, as well as the constant increase in annual mortality due to this infectious disease.

Goal:

The goal was to investigate the prevalence and pneumonia characteristics as the most serious lower respiratory tract infection, the incidence of typical and atypical pneumonia, hospitalization duration of the patients at the Clinic of Infectious Diseases, Clinical Center of Sarajevo University CCUS.

Patients and Methods:

From January 2011 until December 2012 the study involved 100 hospitalized patients with infections of the lower respiratory tract at the Clinic of Infectious Diseases CCUS.

Results:

Among the most common infections the pneumonia is highly represented. Lung X-Ray in two planes, by all protocols, demonstrated with the auscultatory finding has the highest value in the diagnosis of clinical pneumonieae. A statistically significant difference among our hospitalized patients, compared to typical and atypical pneumonia, is in favor of the first–typical bacterial pneumonia. Hospitalization duration ranges between 7-14 days.

Conclusion:

We believe that the introduction of the pneumococcal vaccine (PCV) should reduce the number of pneumonia caused by this bacterium. Recommendations for its use also come from the WHO. Until December 2012, WHO added 86 states in the PCV immunization as a part of their national immunization programs. Pneumococcal conjugate vaccine (PCV) is safe and effective for the reduction in number of patients suffering from pneumonia caused by St. pneumoniae. In particular, the vaccine is a significant protection for children, who due to age and severity of the disease must remain under medical supervision. In elderly vaccine is important and useful as preventive measure, due to their biological characteristics and life circumstances which mark this group as vulnerable population, like the youngest, and can be fatal for them.

Elderly patients with community-acquired pneumonia: optimal treatment strategies

Community-acquired pneumonia (CAP) is a common infectious disease that still causes substantial morbidity and mortality. Elderly people are frequently affected, and several issues related to care of this condition in the elderly have to be considered. This article reviews current recommendations of guidelines with a special focus on aspects of the care of elderly patients with CAP. The most common pathogen in CAP is still Streptococcus pneumoniae, followed by other pathogens such as Haemophilus influenzae, Mycoplasma pneumoniae, Chlamydophila pneumoniae and Legionella species. Antimicrobial resistance is an increasing problem, especially with regard to macrolide-resistant S. pneumoniae and fluoroquinolone-resistant strains. With regard to β-lactam antibacterials, resistance by H. influenzae and Moraxella catarrhalis is important, as is the emergence of multidrug-resistant Staphylococcus aureus. The main management decisions should be guided by the severity of disease, which can be assessed by validated clinical risk scores such as CURB-65, a tool for measuring the severity of pneumonia based on assessment of confusion, serum urea, respiratory rate and blood pressure in patients aged ≥65 years. For the treatment of low-risk pneumonia, an aminopenicillin such as amoxicillin with or without a β-lactamase inhibitor is frequently recommended. Monotherapy with macrolides is also possible, although macrolide resistance is of concern. When predisposing factors for special pathogens are present, a β-lactam antibacterial combined with a β-lactamase inhibitor, or the combination of a β-lactam antibacterial, a β-lactamase inhibitor and a macrolide, may be warranted. If possible, patients who have undergone previous antibacterial therapy should receive drug classes not previously used. For hospitalized patients with non-severe pneumonia, a common recommendation is empirical antibacterial therapy with an aminopenicillin in combination with a β-lactamase inhibitor, or with fluoroquinolone monotherapy. With proven Legionella pneumonia, a combination of β-lactams with a fluoroquinolone or a macrolide is beneficial. In severe pneumonia, ureidopenicillins with β-lactamase inhibitors, broad-spectrum cephalosporins, macrolides and fluoroquinolones are used. A combination of a broad-spectrum β-lactam antibacterial (e.g. cefotaxime or ceftriaxone), piperacillin/tazobactam and a macrolide is mostly recommended. In patients with a predisposition for Pseudomonas aeruginosa, a combination of piperacillin/tazobactam, cefepime, imipenem or meropenem and levofloxacin or ciprofloxacin is frequently used. Treatment duration of more than 7 days is not generally recommended, except for proven infections with P. aeruginosa, for which 15 days of treatment appears to be appropriate. Further care issues in all hospitalized patients are timely administration of antibacterials, oxygen supply in case of hypoxaemia, and fluid management and dose adjustments according to kidney function. The management of elderly patients with CAP is a challenge. Shifts in antimicrobial resistance and the availability of new antibacterials will change future clinical practice. Studies investigating new methods to detect pathogens, determine the optimal antimicrobial regimen and clarify the duration of treatment may assist in further optimizing the management of elderly patients with CAP.

Guidelines for the management of adult lower respiratory tract infections--summary

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. The target audience for the Guideline is thus all those whose routine practice includes the management of adult LRTI.

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.

Outbreak of Pneumococcal Pneumonia among Military Recruits

BACKGROUND

Between 04 Mar 2002 to 21 Mar 2002, 31 cases of pneumonia were admitted at a military hospital in South India. Most of these cases were young recruits. The out break was investigated to ascertain the cause and suggest preventive measures.

METHODS

Detailed epidemiological history was taken from all 31 cases and 100 controls. Case sheets, laboratory reports and chest radiographs were studied. Laboratory investigations included sputum examination by Gram stain and blood cultures on brain heart infusion broth. Cultures grown on liquid media were subcultured on solid media. The regimental centre was visited to note the living and environmental conditions.

RESULTS

Epidemiological investigations revealed overcrowding in the regimental centre. The space per recruit was below recommended standards. 51.6% of recruits who contacted pneumonia were sleeping on double deckers as compared to 21% of healthy controls. Blood culture was positive for Streptococcus pneumoniae in 25.8% of the cases. Chest radiograph showed consolidation typical of lobar pneumonia in 67% of the cases.

CONCLUSION

The outbreak of pneumococcal pneumonia occurred due to overcrowding. Chilly weather conditions and stress were contributing factors.

Diagnostic tests for agents of community-acquired pneumonia

Lower respiratory infections are the major cause of death due to infectious disease in the United States and worldwide. Most forms of community-acquired pneumonia (CAP) are treatable, and there is consensus that the selection of antimicrobial agents is notably simplified if the pathogen is defined. The rich history of CAP studies in the prepenicillin era showed that an etiologic diagnosis was established in >90% of cases, but the 2009 data from Medicare indicate that a probable pathogen is now detected in <10% according to a review of the records of >17,000 patients hospitalized with CAP. This review addresses the issue of the state of the art of microbiological studies of CAP in terms of the realities of current-day practice. Unfortunately, the desire for better data to achieve pathogen-directed treatment clashes with a multitude of harsh realities, including cost, Centers for Medicare and Medicaid Services (CMS) requirements for antibiotics to be administered within 6 h of disease onset, guidelines that discourage any microbiological studies in most cases, belief in empiricism that is well supported by at least 1 prospective study, the decline of microbiological analysis standards in most laboratories, and the devastating impact of the Clinical Laboratory Improvement Amendments (CLIA) regulations that led to the demise of "the house staff laboratory" and the distancing of microbiological analysis from the site of care. Microbiological principles are reviewed, with emphasis on specimen source, pathogenic potential of isolates, concentrations, impact of antecedent antibiotics, and the "Washington criteria" for expectorated sputum. The recommendation is that the high-quality microbiological analysis that is still achieved in some places should be retained but that to advance the field on the basis of the contemporary realities, two goals should be adopted: First is the broad use of antigen tests for Streptococcus pneumoniae and Legionella pneumophila with interpretation by clinical staff under the CLIA waiver for low-complexity tests. The second and more ambitious recommendation is the adoption of molecular techniques, with particular emphasis on nucleic acid detection, which is rapid and sensitive and has already been developed for virtually all recognized pulmonary pathogens. This may be the ultimate solution for many laboratories, and it is likely to have selected use.

Rapid diagnosis of Mycoplasma pneumoniae by polymerase chain reaction in community-acquired lower respiratory tract infections

Two hundred children hospitalized for community-acquired lower respiratory tract infections (LRTIs) were investigated for Mycoplasma pneumoniae employing serological tests and a P1 adhesin gene-based polymerase chain reaction assay (PCR) on nasopharyngeal aspirates. Serological evidence of M. pneumoniae infection was observed in 68 (34%) patients and PCR was positive in 20 (10%) children. Together PCR and/or enzyme immuno assay detected M. pneumoniae in 71(35.5%) children. Our data underline the role of M. pneumoniae in Indian children with community-acquired LRTIs even in children aged < 24 months.

Bacterial pneumonia following cytotoxic chemotherapy for lung cancer: clinical features, treatment outcome and prognostic factors

Data regarding treatment outcomes and prognosis in pneumonia that occurs after lung cancer chemotherapy are lacking. We performed a retrospective study of 84 patients with clinically suspected bacterial pneumonia after cytotoxic chemotherapy for lung cancer. Small cell carcinoma was the most common histological type (36.9%, n = 31), followed by squamous cell carcinoma (35.7%, n = 30) and adenocarcinoma (21.4%, n = 18). The most frequent pathogen was Streptococcus pneumoniae (n = 14), followed by Klebsiella pneumoniae (n = 10), Staphylococcus aureus (n = 8), and Pseudomonas aeruginosa (n = 7). Of 84 patients, treatment outcome was determined for 80; the outcome was success in 52 (61.9%) and failure in 28 (33.3%); outcome remained undetermined for 4 patients (4.8%). Based on multivariate analysis, tachypnoea (respiratory rate ≥20/min) was the only significant predictor of treatment failure (odds ratio 4.79, 95% confidence interval 1.17-19.70; p = 0.030). In conclusion, bacterial pneumonia after cytotoxic chemotherapy for lung cancer was found to be caused more often by S. pneumoniae and K. pneumoniae than P. aeruginosa, and treatment failure leading to death was found to be high. Tachypnoea was independently associated with treatment failure in this population.

Results of a cohort model analysis of the cost-effectiveness of routine immunization with 13-valent pneumococcal conjugate vaccine of those aged > or =65 years in the Netherlands

BACKGROUND

Community-acquired pneumonia and invasive pneumococcal disease are common among older people (ie, those aged > or =65 years). A new 13-valent pneumococcal conjugate vaccine (PCV-13) is under study in the Netherlands.

OBJECTIVE

The aim of this work was to model the cost-effectiveness of PCV-13 vaccination among those aged > or =65 years in the Netherlands, both in the total population and in those at increased risk for pneumonia, for various levels of efficacy (30%-90%) assumed.

METHODS

Our previously published cost-effectiveness model was updated to include age-specific epidemiologic data and health-care utilization and costs for a hypothetical cohort of adults aged > or =65 years in the Netherlands. This cohort was followed twice-once as unvaccinated and once as vaccinated-over a time period of 5 years, with differences between both analyses reported. Outcome measures included costs, life-years gained (LYGs), quality-adjusted life-years, and incremental cost-effectiveness ratios (ICERs). All analyses were performed from a societal perspective.

RESULTS

In the model, the ICER for vaccination remained below euro80,000/LYG, except when the vaccine was assumed to protect only against bacteremic pneumonia, with a relatively low effectiveness (40%) in combination with a high vaccine price (euro65), and indirect effects of serotype replacement would largely offset the direct effect of vaccination. For various assumptions, introduction of widespread PCV-13 vaccination (assuming a 60% efficacy against invasive and noninvasive disease because of vaccine serotypes, and a cost of euro50 per vaccinated person) was associated with the ICERs varying from cost-saving to euro50,676/LYG.

CONCLUSIONS

In this model analysis of a hypothetical cohort in the Netherlands, vaccination with PCV-13 might be considered cost-effective, both for the total population and for the high-risk population aged > or =65 years, from a societal perspective, over a 5-year time horizon. The main limitation of this study was uncertainty regarding how great a proportion of pneumonia could be attributed to pneumococcal disease.

Viral and bacterial interactions in pneumonia

Respiratory tract infections are the most common infectious illnesses that afflict humans. In general, viral infections of the upper respiratory tract result in mild self-limiting symptoms. However, more serious lower respiratory tract infections can lead to the development of pneumonia. While viral infections alone may cause pneumonia, it is increasingly clear that they also play an important role in increasing the risk of bacterial infection and have been shown to substantially worsen clinical outcomes from bacterial pneumonia. Advances in our understanding of the immune response to these infections are beginning to demonstrate how these microorganisms can interact, subvert the normally effective immune response and facilitate the development of more severe and even life-threatening disease.

Pulmonary exacerbations in cystic fibrosis with negative bacterial cultures

BACKGROUND

Pulmonary exacerbations are a major cause of morbidity in cystic fibrosis (CF) and likely contribute to lung function decline. Exacerbations are often associated with characteristic airway bacteria [CF related bacteria (CFRB)]. However, some patients do not have CFRB detected by culture during exacerbations.

OBJECTIVES

We sought to determine the proportion of airway cultures negative for CFRB during pulmonary exacerbations, and to characterize patients who were CFRB-negative versus CFRB-positive.

METHODS

We performed a retrospective study of patients with CF admitted for a pulmonary exacerbation. Patients were classified as CFRB-positive or CFRB-negative based on admission airway cultures. Demographics, clinical presentation, lung function, history of chronic Pseudomonas aeruginosa infection and improvement in lung function with treatment were compared between groups.

MAIN RESULTS

There were 672 admissions for exacerbation involving 211 patients over 5 years. Seventeen percent were classified as CFRB-negative. Forty-one percent of bronchoalveolar lavage (BAL), 32% of throat and 10% of sputum samples were CFRB-negative. Among patients capable of expectorating sputum, the CFRB-negative group was younger, less likely to have chronic P. aeruginosa, had higher lung function and body mass index (BMI), and had a lower systemic inflammatory response on admission compared to those with CFRB-positive cultures. The two groups had similar numbers of patients with three or more signs and symptoms of a pulmonary exacerbation (88% vs. 92%). Both groups returned to baseline lung function following treatment.

CONCLUSIONS

A significant number of patients with CF and pulmonary exacerbation did not have typical CFRB detected by culture. Patients without CFRB still had characteristic signs and symptoms of pulmonary exacerbation and responded to treatment. Understanding the causes of illness in these patients may improve the diagnosis and treatment of pulmonary exacerbations in CF.

Streptococcus pneumoniae DNA load in blood as a marker of infection in patients with community-acquired pneumonia

Direct detection of Streptococcus pneumoniae DNA in blood adds to culture results in the etiological diagnosis of patients with community-acquired pneumonia (CAP). Quantification of the amount of DNA, the bacterial DNA load (BDL), provides a measurement of DNAemia that may increase the understanding of the clinical relevance of S. pneumoniae DNA in blood. We evaluated the S. pneumoniae BDL as a diagnostic tool in adult patients with CAP. The BDL was determined in whole-blood samples collected simultaneously with blood for culture from 45 adult patients with CAP. After DNA extraction, S. pneumoniae DNA was detected with specific real-time PCR amplification, and the BDL was calculated with a standard curve. PCR and microbiological results were compared, and the BDL was related to clinical and laboratory parameters. S. pneumoniae DNA was detected in 10/13 patients with positive blood cultures and in 67% of patients with microbiologically confirmed pneumococcal pneumonia. The positive predictive values of the receiver operating characteristic curves for the BDLs for pneumococcal infection (100%) and pneumococcal bacteremia (69%) were higher than those for the level of C-reactive protein (CRP; 43% and 23%, respectively) and the white blood cell count (WBC; 42% and 35%, respectively); the negative predictive values of these three parameters were in the same range (+/-90 and +/-97%, respectively). The BDL was higher in patients presenting with systemic inflammatory response syndrome and in patients with bacteremia. Positive correlations were observed for the BDL with WBC, CRP level, and length of stay. We conclude that the BDL supports the diagnosis of S. pneumoniae infection in patients with CAP and provides a putative marker of the severity of disease.

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

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

Inflammatory parameters predict etiologic patterns but do not allow for individual prediction of etiology in patients with CAP: results from the German competence network CAPNETZ

Background

Aim of this study was to evaluate the correlation of inflammatory markers procalcitonin (PCT), C-reactive protein (CRP) and leukocyte count (WBC) with microbiological etiology of CAP.

Methods

We enrolled 1337 patients (62 ± 18 y, 45% f) with proven CAP. Extensive microbiological workup was performed. In all patients PCT, CRP, WBC and CRB-65 score were determined. Patients were classified according to microbial diagnosis and CRB-65 score.

Results

In patients with typical bacterial CAP, levels of PCT, CRP and WBC were significantly higher compared to CAP of atypical or viral etiology. There were no significant differences in PCT, CRP and WBC in patients with atypical or viral etiology of CAP. In contrast to CRP and WBC, PCT markedly increased with severity of CAP as measured by CRB-65 score (p < 0.0001). In ROC analysis for discrimination of patients with CRB-65 scores > 1, AUC for PCT was 0.69 (95% CI 0.66 to 0.71), which was higher compared to CRP and WBC (p < 0.0001). CRB-65, PCT, CRP and WBC were higher (p < 0.0001) in hospitalised patients in comparison to outpatients.

Conclusion

PCT, CRP and WBC are highest in typical bacterial etiology in CAP but do not allow individual prediction of etiology. In contrast to CRP and WBC, PCT is useful in severity assessment of CAP.

Geographical variation of sporadic Legionnaires' disease analysed in a grid model

The aim was to analyse variation in incidence of sporadic Legionnaires' disease in a geographical information system in three time periods (1990–2005) by the application of a grid model and to assess the model's validity by analysing variation according to grid position. Coordinates of the addresses at time of disease of 606 confirmed cases with Legionnaires' disease were obtained. The incidence was calculated in cells of 10×10 km in 25 different grids superimposed on a map of Denmark. A 95% and 99% threshold was applied to identify cells with excess incidence representing potential clusters. Four cells had excess incidence in all three time periods. The analysis in 25 different grid positions indicated a low risk of overlooking cells with excess incidence in a random grid. The coefficient of variation ranged from 0·08 to 0·11 independent of the threshold. By application of a random grid model we demonstrated that it was possible to detect small areas with excess incidence that were not detected in the present surveillance system.

Clinical features predicting failure of pathogen identification in patients with community acquired pneumonia

Community acquired pneumonia (CAP) is caused by a variety of microorganisms. By identifying patients at risk for failure of pathogen identification, it is possible to make an early decision on the extent of diagnostic procedures to be performed. This is especially important in patients with severe CAP. The aim of this study was to identify these patients by using clinical and laboratory features. In 201 patients hospitalized for CAP, clinical and laboratory variables were collected. Pathogen identification was performed by culture of sputum and blood, urine antigen tests, polymerase chain reaction of sputum, serological testing and viral culture of the pharynx. In 128 patients a respiratory microorganism was identified. In both univariate and multivariate analysis, failure of pathogen identification was predicted by pre-hospital antibiotic therapy, a medical history of hypertension and a low C-reactive protein. We conclude that patients with pre-hospital antibiotic therapy, a medical history of hypertension and a relatively low C-reactive protein are at risk for failure of pathogen identification. These predictors should be confirmed in a larger population. Invasive testing in high-risk patients with CAP in the presence of these predictors should be considered at an early phase of hospitalization.

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.

Development and evaluation of a novel multiplex PCR technology for molecular differential detection of bacterial respiratory disease pathogens

The ResPlex I assay (Qiagen) was designed to amplify and detect DNA of six bacterial respiratory pathogens. This assay was compared with real-time PCR assays based upon the same target sequences for the ability detect the target bacteria by use of both stock strains and specimens from respiratory disease patients. The ResPlex I assay is somewhat less sensitive than real-time PCR assays but offers the advantage of multiple assays in a single reaction.

Incidence and completeness of notification of Legionnaires' disease in The Netherlands: covariate capture-recapture analysis acknowledging regional differences

To estimate incidence and completeness of notification of Legionnaires' disease (LD) in The Netherlands in 2000 and 2001, we performed a capture-recapture analysis using three registers: Notifications, Laboratory results and Hospital admissions. After record-linkage, 373 of the 780 LD patients identified were notified. Ascertained under-notification was 52.2%. Because of expected and observed regional differences in the incidence rate of LD, alternatively to conventional log-linear capture-recapture models, a covariate (region) capture-recapture model, not previously used for estimating infectious disease incidence, was specified and estimated 886 LD patients (95% confidence interval 827-1022). Estimated under-notification was 57.9%. Notified, ascertained and estimated average annual incidence rates of LD were 1.15, 2.42 and 2.77/100 000 inhabitants respectively, with the highest incidence in the southern region of The Netherlands. Covariate capture-recapture analysis acknowledging regional differences of LD incidence appears to reduce bias in the estimated national incidence rate.

Bacterial Infections

In Osier’s time, bacterial pneumonia was a dreaded event, so important that he borrowed John Bunyan’s characterization of tuberculosis and anointed the pneumococcus, as the prime pathogen, “Captain of the men of death.”1 One hundred years later much has changed, but much remains the same. Pneumonia is now the sixth most common cause of death and the most common lethal infection in the United States. Hospital-acquired pneumonia is now the second most common nosocomial infection.2 It was documented as a complication in 0.6% of patients in a national surveillance study,3 and has been reported in as many as 20% of patients in critical care units.4 Furthermore, it is the leading cause of death among nosocomial infections.5 Leu and colleagues6 were able to associate one third of the mortality in patients with nosocomial pneumonia to the infection itself. The increase in hospital stay, which averaged 7 days, was statistically significant. It has been estimated that nosocomial pneumonia produces costs in excess of $500 million each year in the United States, largely related to the increased length of hospital stay.

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.

Bacterial community-acquired pneumonia in older patients

Pneumonia in the elderly remains a major source of morbidity and mortality in an age group that is growing in numbers. It remains unclear whether the propensity of older adults to develop community-acquired pneumonia represents an aging of host defenses, secondary effects of comorbid disease, or both. The signs and symptoms of pneumonia in the elderly are more subtle than in younger populations, which may lead to a delay in diagnosis. Although therapy for community-acquired pneumonia in the elderly is the same as for younger populations, mortality is higher, leading to an important role for prevention.

Comparison of polymerase chain reaction and the indirect particle agglutination antibody test for the diagnosis of Mycoplasma pneumoniae pneumonia in children during two outbreaks

BACKGROUND

Diagnosis of Mycoplasma pneumoniae pneumonia is challenging because of the lack of standardized rapid tests. Many serologic tests and polymerase chain reaction (PCR) based methods are used with different diagnostic criteria.

METHODS

This retrospective study was conducted to compare the diagnostic values of the indirect particle agglutination test and nested PCR of nasopharyngeal aspirates for the diagnosis of M. pneumoniae pneumonia in children. These assays were evaluated in 234 hospitalized children with community-acquired lower respiratory tract infections during 2 outbreaks of M. pneumoniae pneumonia in 2000 and 2003.

RESULTS

The cumulative PCR positive rate was 26.7% in patients with maximum antibody titers of < or =1:320 and 78.2% in those with titers of > or =1:640. Based on these data, a positive PCR, a 4-fold increase in antibody titer, or a single titer > or =1:640 were considered to indicate acute M. pneumoniae infection. Overall, 152 children were diagnosed to have M. pneumoniae pneumonia; 27 (18%) by serology only, 26 (17%) by PCR only, and 99 (65%) by both methods. Children who were diagnosed by PCR only were significantly younger (P = 0.003) and were more often immunocompromised (P = 0.019) than those that were PCR negative. Duration of cough before PCR diagnosis was shorter in cases diagnosed by PCR only than those that were PCR negative (P = 0.045).

CONCLUSIONS

In conclusion, during the 2 outbreaks of M. pneumoniae infection, we found that the PCR test may be useful for the rapid diagnosis of M. pneumoniae pneumonia, particularly in young children and in immunocompromised patients and in early stage disease.

Community-acquired lung abscess caused by Legionella micdadei in a myeloma patient receiving thalidomide treatment

Legionella infection causes 2 to 14% of community-acquired pneumonia (CAP). Legionella micdadei constitutes <1% of these infections. We describe a case of cavitary L. micdadei CAP in a myeloma patient receiving thalidomide treatment. The importance of considering pneumonia and problems in diagnosing pneumonia caused by L. micdadei in this patient population are reviewed.

[Managing lower respiratory tract infections in immunocompetent patients. Definitions, epidemiology, and diagnostic features]

Les infections respiratoires basses sont une des principales cause de mortalité dans le monde et les pneumopathies représentent en France la première cause de décès d'origine infectieuse. Trois entités nosologiques distinctes sont habituellement isolées en fonction de la localisation infectieuse : la bronchite aiguë, la pneumopathie et la bronchopneumopathie (atteignant les bronches et le parenchyme pulmonaire). En cas d'infections de l'arbre bronchique dans le cadre d'une bronchopathie chronique on parle de décompensation infectieuse de la maladie bronchique. Les deux principales difficultés diagnostiques de ces infections sont de déterminer la présence d'une participation alvéolaire au processus infectieux et de définir l'agent (ou les agents) pathogènes. Ces deux éléments vont conditionner la prise en charge thérapeutique. En dehors de l'examen physique, indispensable dans ce contexte, seule la radiographie thoracique pourra, en cas de persistance d'un doute, permettre de confirmer la présence d'une participation alvéolaire. Le diagnostic microbiologique pose la question de sa nécessité systématique et celui de sa valeur. Il n'est pas indispensable de réaliser un diagnostic microbiologique de certitude dans tous les cas. La décision de documentation doit répondre à deux impératifs : faisabilité et valeur diagnostique. La valeur d'un prélèvement dépend de son aptitude à mettre en évidence l'agent pathogène et dans certains cas de la possibilité d'en déterminer le profil de sensibilité (qui reste une indication majeure à la réalisation de ces prélèvements).

Sensitivity of three serum antibody tests in a large outbreak of Legionnaires' disease in the Netherlands

In 1999, an outbreak involving 188 patients with Legionnaires' disease (LD) occurred at a flower show in the Netherlands. This large outbreak provided the opportunity to evaluate serum antibody tests to assay anti-Legionella pneumophila, since limited data are available on the sensitivity of these tests. The sensitivities of an indirect serotype 1-6 immunofluorescence antibody test (IFAT), a rapid micro-agglutination test (RMAT) IgM serotype 1 antibody assay, and an ELISA to detect IgM and IgG serotype 1-7 antibodies, were evaluated using serum samples from LD patients related to the 1999 outbreak. Sensitivity was calculated using positive culture and/or a positive urinary antigen test as the gold standard in outbreak-related patients with radiographically confirmed pneumonia who fulfilled the epidemiological criteria. The IFAT, RMAT and ELISA showed sensitivities of 61, 44 and 64%, respectively. The sensitivity of the three tests combined was 67%. In epidemic situations, however, high standing titres may be included in the laboratory evidence of LD cases. In the study population, high standing titres were found in 16% of cases. If the presence of high standing antibody titres was added to the criteria of a positive test, the sensitivities of IFAT, RMAT and ELISA were 86, 48 and 75%, respectively. The sensitivity was 91% for all tests combined. The higher sensitivity for the combined use of tests is offset by a reduction in specificity to 97.6%. The results of this study indicate that using a combination of serologic tests in pneumonia patients suspected to have LD does not substantially improve sensitivity. The results suggest that in the microbiological diagnosis of LD, both IFAT and ELISA are reasonably sensitive assays. In an epidemic situation, both tests are highly sensitive, the IFAT more so than the ELISA.

Chlamydia pneumoniae and Mycoplasma pneumoniae pneumonia: comparison of clinical, epidemiological characteristics and laboratory profiles

The purpose of our retrospective 3-year study was to analyse and compare clinical and epidemiological characteristics in hospitalized patients older than 6 years with community-acquired pneumonia (CAP) caused by Chlamydia pneumoniae (87 patients) and Mycoplasma pneumoniae (147 patients). C. pneumoniae and M. pneumoniae infection was confirmed by serology. C. pneumoniae patients were older (42.12 vs. 24.64 years), and were less likely to have a cough, rhinitis, and hoarseness (P<0.001). C. pneumoniae patients had higher levels of C-reactive protein (CRP), and aspartate aminotransferase (AST) than M. pneumoniae patients (P<0.001). Pleural effusion was recorded more frequently in patients with M. pneumoniae (8.84 vs. 3.37%). There were no characteristic epidemiological and clinical findings that would distinguish CAP caused by M. pneumoniae from C. pneumoniae. However, some factors are indicative for C. pneumoniae such as older age, lack of cough, rhinitis, hoarseness, and higher value of CRP, and AST.

Effectiveness of a 23-valent polysaccharide vaccine in preventing pneumonia and non-invasive pneumococcal infection in elderly people: a large-scale retrospective cohort study

This retrospective cohort study evaluated the effectiveness of a 23-valent pneumococcal polysaccharide vaccine in reducing hospital admission for pneumonia, otitis media and exacerbation of asthma or other syndromes due to Streptococcus pneumoniae in 9170 high-risk individuals. Cohort members were followed from 1 January 1998 to 31 December 2002. With regard to preventing hospitalization due to pneumonia, we observed a decrease in the incidence of 1/10000 person-months and a reduction in the relative risk of 38% in the vaccinated cohort compared with the non-vaccinated subjects. A decrease in the risk of hospital admission for asthma, acute otitis media, chronic obstructive pulmonary disease and other respiratory infections was also observed in vaccinated compared with non-vaccinated subjects. The specificity of these findings was confirmed by the lack of a protective effect from vaccination for those outcomes, such as hospitalization 'for all causes' and 'other otorhinolaryngological diagnoses', that were not directly related to pneumococcal disease.