Etiology of community-acquired pneumonia. Evaluation by transtracheal aspiration, blood culture, or serology

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.

Complete Genome Sequence of Pseudomonas stutzeri Type Strain SGAir0442, Isolated from Singapore Air Samples

Pseudomonas stutzeri strain SGAir0442 was isolated from tropical air samples collected in Singapore. It is a Gram-negative denitrifying bacterium and an opportunistic human pathogen. Its complete genome consists of one chromosome of 4.52 Mb, containing 4,129 protein-coding genes, 12 rRNA subunits, and 62 tRNAs.

Reasons for choice of antibiotic for the empirical treatment of CAP by Canadian infectious disease physicians

BACKGROUND

Previous studies have documented substantial variation in physician prescribing practices for the treatment of community-acquired pneumonia. Much of this variation is the result of empirical treatment, in which physicians must choose antibiotics in the a8bsence of culture and sensitivity data.

OBJECTIVE

To explore the factors that influence antibiotic choice for the empirical treatment of community-acquired pneumonia.

MATERIALS AND METHODS

Case-based questionnaires were mailed to all 157 members of the Canadian Infectious Disease Society in June 1996. The questionnaires presented three clinical cases and asked respondents which antibiotics they would most likely prescribe. Half the questionnaires were closed-ended, and half were open-ended. In the former, respondents were asked to explain their antibiotic choice by assigning weights to a list of clinical factors. In the latter, respondents were asked to explain their antibiotic choice by providing a short written answer. Respondents were grouped by the class of antibiotics they selected. These groups were then compared with regards to respondent characteristics (age, years of infectious disease experience, adult versus pediatric practice, country of training, province of practice) and rationale for the treatment chosen. Rationale for drug choice was analyzed statistically for the closed-ended questionnaires and qualitatively for the open-ended questionnaires.

RESULTS

A response rate of 84.6% was obtained. For the first clinical case, in which the patient was young and had no underlying illness, the majority of respondents chose a macrolide (74.7%). In the second case, in which the patient was older and had evidence of comorbidity, the most common choice of antibiotic was a penicillin (40.8%). In the third case, in which the patient had intensive care unit-requiring pneumonia, the most popular choice was combination therapy of a third-generation cephalosporin and a macrolide (43.2%). There was decreasing consensus regarding the choice of antibiotics as the complexity of the cases increased. There was evidence that prescribing variation could occasionally be attributed to both respondent characteristics and the use of different decision-making strategies.

CONCLUSIONS

Despite the relative homogeneity of the physicians studied, considerable variation in antibiotic choice was observed. In the first case, this variation was based on the issue of whether the patient had a typical or atypical infection. In the second case, the choice of antibiotic was related to the issue of infection by Haemophilus influenzae, although the results of the Gram stain suggested a pneumococcal infection. In the third case, variance appeared to be based more on the respondent's age and province of practice than on any difference in decision-making strategy.

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.

Definite, probable, and possible bacterial aetiologies of community-acquired pneumonia at different CRB-65 scores

According to the recommendations of the Swedish Community-Acquired Pneumonia (CAP) guidelines, the selection of empirical antibiotic therapy should be based on the CRB-65 rule. The guidelines recommend empirical therapy directed predominantly against Streptococcus pneumoniae for patients with low CRB-65 scores and broad-spectrum therapy for patients with high CRB-65 scores. In order to study the utility of the recommendations, we analyzed the data from an aetiological study previously performed on 235 hospitalized adult CAP patients at our medical centre. A definite, probable, or possible bacterial aetiology was noted in 194 cases (83%), including 112 cases (48%) with S. pneumoniae aetiology. The following frequencies of definite-probable aetiologies were noted in the patients with CRB-65 score 0-1 (n=155) and CRB-65 score 2-4 (n=80): S. pneumoniae 30% and 35%, Haemophilus influenzae 6.5% and 14% (p=0.063), Mycoplasma pneumoniae 15% and 5.0% (p=0.019), Chlamydophila species 2.6% and 1.2%, Legionella pneumophila 1.9% and 0%, and Staphylococcus aureus 1.3% and 1.2%, respectively. The high frequency of S. pneumoniae in the study supports the recommendations to predominantly cover this bacterium in the empirical therapy of patients with low CRB-65 scores. In the case of treatment failure in these patients, the study indicates that coverage against M. pneumoniae and H. influenzae should be considered.

Utility of a pneumonia severity index in the optimization of the diagnostic and therapeutic effort for community-acquired pneumonia

The objective was to evaluate the utility of the Pneumonia Severity Index (PSI) developed by Fine et al. as a tool to streamline diagnostic and therapeutic effort. Site of care of patients was recommended in accordance with the PSI class: classes I and II underwent treatment at home and classes III, IV, and V were hospitalized. Class I comprised 37 patients; class II had 30, class III had 20, class IV had 31, and class V had 10 patients. 80 patients were admitted into the hospital, 3 of whom required admittance to the intensive care unit, and 48 were managed as outpatients from the emergency room. Overall mortality was 4 patients (3.1%). Of these, 3 belonged to class IV and 1 to class V. The aetiological diagnosis was obtained in 53.9% of the cases (69/128). If classes I to III are analysed together, the percentage of aetiological diagnoses was 47% (41/87), increasing to 68% (28/41) for patients in classes IV and V. In our experience Fine's PSI classification, with rationalization and adaptation to the particularities of each centre, is an effective tool for deciding on hospitalization for selecting the most suitable battery of diagnostic tests based on cost-benefit criteria. However, it is inadequate for young patients with hypoxia or pleural effusion. Therefore, although hospitalization of patients with pneumonia should be mainly based on clinical criteria, Fine's PSI classification could help physicians in making more rational decisions in this respect.

Predicting Positive Blood Cultures in Patients presenting with Pneumonia at an Emergency Department in Singapore

Introduction: Routine blood cultures have been recommended for all patients in treatment guidelines for community-acquired pneumonia (CAP). This practice has become a major area of resource utilisation, despite the lack of evidence in its clinical utility. Calls for abandoning the practice is balanced by the occasions of uncovering an unexpected pathogen or an unusual antimicrobial resistance pattern. The aim of this study is to identify factors that predict positive blood cultures among patients hospitalised for pneumonia upon presentation at the Emergency Department (ED). Materials and Methods: A case control study was carried out on patients treated for pneumonia in the ED who had routine blood cultures performed as part of their management. The pneumonia severity index (PSI) was used to categorise patients into low- and high-risk for 30-day mortality. Logistic regression was carried out to determine factors significantly associated with positive blood cultures, from which a predictive probability equation was used to identify patients whose blood cultures were negative at a pre-determined cut-off, with minimum number of culture positive misclassification. A scoring system was devised, with scores predicting which patients would be likely to have a positive or negative blood culture. Results: A total of 1407 patients with pneumonia were treated at ED from May to December 2006, from whom 1800 blood cultures were performed. Of these, 140 cultures (7.8%) grew organisms, comprising 96 (5.3%) true positive cultures and 44 (2.4%) contaminated cultures. Logistic regression analysis identified ill patients with higher PSI classes, smokers and Malay patients to be more likely to have positive blood cultures. Patients who had prior treatment with antibiotics, chronic obstructive pulmonary disease and cough were less likely to have positive blood cultures. An index to predict a negative blood culture resulted in the accurate classification of all but 4 positive patients while still correctly classifying 27.8% of blood culture negative patients. The area under the ROC curve was 0.71 (95% CI, 0.65-0.76). A simplified scoring system was devised based on the predictive model had a sensitivity of 82% and specificity of 38.2% for a positive blood culture. Conclusion: Routine blood cultures yielded negative results in 94% of patients presenting with pneumonia. The development of the clinical scoring system is a first step towards selecting patients for whom blood cultures is performed and improve cost-effectiveness. Introduction: Routine blood cultures have been recommended for all patients in treatment guidelines for community-acquired pneumonia (CAP). This practice has become a major area of resource utilisation, despite the lack of evidence in its clinical utility. Calls for abandoning the practice is balanced by the occasions of uncovering an unexpected pathogen or an unusual antimicrobial resistance pattern. The aim of this study is to identify factors that predict positive blood cultures among patients hospitalised for pneumonia upon presentation at the Emergency Department (ED). Materials and Methods: A case control study was carried out on patients treated for pneumonia in the ED who had routine blood cultures performed as part of their management. The pneumonia severity index (PSI) was used to categorise patients into low- and high-risk for 30-day mortality. Logistic regression was carried out to determine factors significantly associated with positive blood cultures, from which a predictive probability equation was used to identify patients whose blood cultures were negative at a pre-determined cut-off, with minimum number of culture positive misclassification. A scoring system was devised, with scores predicting which patients would be likely to have a positive or negative blood culture. Results: A total of 1407 patients with pneumonia were treated at ED from May to December 2006, from whom 1800 blood cultures were performed. Of these, 140 cultures (7.8%) grew organisms, comprising 96 (5.3%) true positive cultures and 44 (2.4%) contaminated cultures. Logistic regression analysis identified ill patients with higher PSI classes, smokers and Malay patients to be more likely to have positive blood cultures. Patients who had prior treatment with antibiotics, chronic obstructive pulmonary disease and cough were less likely to have positive blood cultures. An index to predict a negative blood culture resulted in the accurate classification of all but 4 positive patients while still correctly classifying 27.8% of blood culture negative patients. The area under the ROC curve was 0.71 (95% CI, 0.65-0.76). A simplified scoring system was devised based on the predictive model had a sensitivity of 82% and specificity of 38.2% for a positive blood culture. Conclusion: Routine blood cultures yielded negative results in 94% of patients presenting with pneumonia. The development of the clinical scoring system is a first step towards selecting patients for whom blood cultures is performed and improve cost-effectiveness.

Biology of Pseudomonas stutzeri

Pseudomonas stutzeri is a nonfluorescent denitrifying bacterium widely distributed in the environment, and it has also been isolated as an opportunistic pathogen from humans. Over the past 15 years, much progress has been made in elucidating the taxonomy of this diverse taxonomical group, demonstrating the clonality of its populations. The species has received much attention because of its particular metabolic properties: it has been proposed as a model organism for denitrification studies; many strains have natural transformation properties, making it relevant for study of the transfer of genes in the environment; several strains are able to fix dinitrogen; and others participate in the degradation of pollutants or interact with toxic metals. This review considers the history of the discovery, nomenclatural changes, and early studies, together with the relevant biological and ecological properties, of P. stutzeri.

Neumonías comunitarias graves del adulto

Las neumonías agudas comunitarias son causa frecuente de hospitalización y mortalidad. El reconocimiento inmediato de las formas graves según criterios simples, clínicos, radiológicos y de laboratorio, es una etapa esencial para un tratamiento rápido en el servicio de reanimación con el fin de controlar los fallos orgánicos. La obtención de muestras apropiadas para realizar estudios microbiológicos precede al tratamiento antibiótico, que se debe instaurar con rapidez después de diagnosticar la neumonía. Pese a las técnicas de identificación, sólo la mitad de las neumonías se documentan adecuadamente. El tratamiento antibiótico, en principio empírico, integra los gérmenes patógenos, tanto extracelulares como intracelulares, que producen neumonías con mayor frecuencia; siempre debe ser activo contra el neumococo, la bacteria implicada más a menudo. La asociación de un betalactámico y un macrólido o una fluoroquinolona es la que mejor responde a este objetivo. En las recomendaciones más comunes, las fluoroquinolonas activas contra los neumococos sustituyen a los fármacos precedentes. En el caso excepcional de los pacientes con factores de riesgo especiales, el tratamiento empírico debe tener en cuenta Pseudomonas aeruginosa. La gravedad de parte de las neumonías comunitarias justifica el que se recurra a tratamientos complementarios. Se debe evaluar de nuevo el tratamiento antibiótico en las 72 horas siguientes a su instauración, a fin de valorar su eficacia, adaptar el tratamiento en caso necesario y simplificarlo. El mantenimiento de antibióticos de amplio espectro expone al paciente a efectos secundarios y contribuye a producir resistencias bacterianas. En cuanto a las neumonías neumocócicas, las fluoroquinolonas activas contra el neumococo podrían representar una alternativa en caso de que el neumococo desarrolle resistencia a los betalactámicos. La mortalidad persistente de las neumonías sigue siendo notable. Esto debe fomentar la mejora del tratamiento inicial y la búsqueda de nuevas opciones terapéuticas.

Streptococcus pneumoniae: description of the pathogen, disease epidemiology, treatment, and prevention

Streptococcus pneumoniae causes significant morbidity and mortality. Children younger than 2 years and individuals older than 65 years experience the highest rates of pneumococcal disease. Efforts to treat pneumococcal disease have been complicated by increasing resistance to antimicrobials. Prevention efforts have included the pneumococcal polysaccharide vaccines and the pneumococcal conjugate vaccines, with use of these vaccines targeted to those at highest risk for disease. Information and background on S. pneumoniae and pneumococcal disease are provided. Vaccines targeted at this pathogen are reviewed, and the clinical trials that evaluated their safety, efficacy, and effectiveness are summarized. Also provided are recommendations for use of these vaccines.

The spectrum of practice in the diagnosis and management of pneumonia in patients requiring mechanical ventilation. Australian and New Zealand practice in intensive care (ANZPIC II)

This study of ventilated patients investigated current clinical practice in 476 episodes of pneumonia (48% community-acquired pneumonia, 24% hospital-acquired pneumonia, 28% ventilator-associated pneumonia) using a prospective survey in 14 intensive care units (ICUs) within Australia and New Zealand. Diagnostic methods and confidence, disease severity, microbiology and antibiotic use were assessed. All pneumonia types had similar mortality (community-acquired pneumonia 33%, hospital-acquired pneumonia 37% and ventilator-associated pneumonia 24%, P=0.15) with no inter-hospital differences (P=0.08-0.91). Bronchoscopy was performed in 26%, its use predicted by admission hospital (one tertiary: OR 9.98, CI 95% 5.11-19.49, P< 0.001; one regional: OR 6.29, CI 95% 3.24-12.20, P<0.001), clinical signs of consolidation (OR 3.72, CI 95% 2.09-6.62, P<0.001) and diagnostic confidence (OR 2.19, CI 95% 1.29-3.72, P=0.004). Bronchoscopy did not predict outcome (P=0.11) or appropriate antibiotic selection (P=0.69). Inappropriate antibiotic prescription was similar for all pneumonia types (11-13%, P=0.12) and hospitals (0-16%, P=0.25). Blood cultures were taken in 51% of cases. For community-acquired pneumonia, 70% received a third generation cephalosporin and 65% a macrolide. Third generation cephalosporins were less frequently used for mild infections (OR 0.38, CI 95% 0.16-0.90, P=0.03), hospital-acquired pneumonia (OR 0.40, CI 95% 0.23-0.72, P<0.01), ventilator-associated pneumonia (OR 0.04, CI 95% 0.02-0.13, P<0.001), suspected aspiration (OR 0.20, CI 95% 0.04-0.92, P=0.04), in one regional (OR 0.26, CI95% 0.07-0.97, P=0.05) and one tertiary hospital (OR 0.14, CI 95% 0.03-0. 73, P=0.02) but were more commonly used in older patients (OR 1.02, CI 95% 1.01-1.03, P=0.01). There is practice variability in bronchoscopy and antibiotic use for pneumonia in Australian and New Zealand ICUs without significant impact on patient outcome, as the prevalence of inappropriate antibiotic prescription is low. There are opportunities for improving microbiological diagnostic work-up for isolation of aetiological pathogens.

Pneumonies communautaires graves de l'adulte

Les pneumonies aiguës communautaires sont des causes fréquentes d'hospitalisation et de mortalité. La reconnaissance immédiate des formes sévères sur des critères simples, cliniques, radiologiques et biologiques, est une étape importante pour une prise en charge rapide en réanimation afin de contrôler les défaillances d'organes. Les prélèvements appropriés microbiologiques précèdent l'antibiothérapie qui doit être instituée très rapidement après le diagnostic de pneumonie. Malgré les techniques d'identification, la moitié seulement des pneumonies sont documentées. Cette antibiothérapie, initialement probabiliste, intègre les germes pathogènes les plus souvent responsables, extra- et intracellulaires ; elle doit toujours être active sur le pneumocoque, bactérie la plus fréquente. L'association d'une β-lactamine et d'un macrolide ou d'une fluoroquinolone répond le mieux à cet objectif. Les fluoroquinolones actives sur le pneumocoque se sont substituées aux précédentes dans les plus récentes recommandations. Dans le cas exceptionnel des patients ayant des facteurs de risque particuliers, le traitement probabiliste doit prendre en compte Pseudomonas aeruginosa. La gravité d'une partie des pneumonies communautaires justifie le recours à des traitements adjuvants. L'antibiothérapie doit être réévaluée dans les 72 heures dans le but d'apprécier son efficacité, de l'adapter éventuellement et de la simplifier. La poursuite des antibiotiques à large spectre expose le patient à des effets indésirables et contribue aux résistances bactériennes. Pour les pneumonies dues au pneumocoque, les fluoroquinolones actives sur le pneumocoque pourront constituer une alternative en cas d'évolution importante des résistances du pneumocoque aux β-lactamines. La mortalité persistante des pneumonies reste sévère. Ceci doit stimuler l'amélioration de la prise en charge initiale et faire rechercher de nouvelles thérapeutiques.

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

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

Comparative in vitro activity of a pharmacokinetically enhanced oral formulation of amoxicillin/clavulanic acid (2000/125 mg twice daily) against 9172 respiratory isolates collected worldwide in 2000

OBJECTIVES

A new, pharmacokinetically enhanced, oral formulation of amoxicillin/clavulanic acid has been developed to overcome resistance in the major bacterial respiratory pathogen Streptococcus pneumoniae, while maintaining excellent activity against Haemophilus influenzae and Moraxella catarrhalis, including beta-lactamase producing strains. This study was conducted to provide in vitro susceptibility data for amoxicillin/clavulanic acid and 16 comparator agents against the key respiratory tract pathogens.

METHODS

Susceptibility testing was performed on 9172 isolates collected from 95 centers in North America, Europe, Australia, and Hong Kong by broth microdilution MIC determination, according to NCCLS methods, using amoxicillin/clavulanic acid and 16 comparator antimicrobial agents. Results were interpreted according to NCCLS breakpoints and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints based on oral dosing regimens.

RESULTS

Overall, 93.5% of Streptococcus pneumoniae isolates were susceptible to amoxicillin/clavulanic acid at the current susceptible breakpoint of < or =2 microg/mL and 97.3% at the PK/PD susceptible breakpoint of < or =4 microg/mL for the extended release formulation. Proportions of isolates that were penicillin intermediate and resistant were 13% and 16.5%, respectively, while 25% were macrolide resistant and 21.8% trimethoprim/sulfamethoxazole resistant. 21.9% of Haemophilus influenzae were beta-lactamase producers and 16.8% trimethoprim/sulfamethoxazole resistant, >99% of isolates were susceptible to amoxicillin/clavulanic acid, cefixime, ciprofloxacin and levofloxacin at NCCLS breakpoints. The most active agents against Moraxella catarrhalis were amoxicillin/clavulanic acid, macrolides, cefixime, fluoroquinolones, and doxycycline. Overall, 13% of Streptococcus pyogenes were resistant to macrolides.

CONCLUSION

The extended release formulation of amoxicillin/clavulanic acid has potential for empiric use against many respiratory tract infections worldwide due to its activity against species resistant to many agents currently in use.

[Uncommon cause of respiratory distress in the post-anaesthesia care unit]

We report a case of respiratory distress in the post anesthesia care unit following general anaesthesia for a dilatation and curettage related to miscarriage in a 32-year-old woman. The preoperative physical examination showed no abnormalities except for the presence of dry cough during the preceding two or three days. A few minutes after her arrival in the PACU, the patient developed hyperthermia till 40.6 degrees C, cough, polypnea and oxygen desaturation (SpO(2): 82% on FiO(2): 40%). A thoraco-abdominal angioscanner showed pulmonary basal condensations and a thrombosis of the right ovarian vein. The patient had to be transferred to the intensive care unit where she remained intubated and ventilated during 13 days because of a Haemophilus influenzae pneumonia.

Imagerie moderne des pneumonies infectieuses aiguës

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

What is the clinical impact of macrolide resistance?

Respiratory tract infections are treated empirically. Treatment is based on the likely pathogens and their antibiotic susceptibility. The most common respiratory tract pathogen is Streptococcus pneumoniae. In the United States, approximately 25% to 30% of S. pneumoniae are resistant to erythromycin and other macrolides. There are two mechanisms of resistance: ribosomal methylation that causes high-level resistance, and an efflux pump that causes low-level resistance. Macrolides are ineffective in animal models that use pneumococcal isolates with the methylase- or efflux-mediated resistance mechanisms. There are many case reports that describe clinical failure and isolation of a macrolide-resistant pneumococcus while a patient receives macrolide treatment. Two recent studies that included macrolide-susceptible and macrolide-resistant pneumococci showed that breakthrough bacteremia in patients receiving macrolide treatment occurred only with macrolide-resistant isolates. Study of bacteremic disease ensures the pathogenic role of the pneumococcus; however, it underestimates the true clinical impact of macrolide resistance.

Oral infections and systemic diseases

An association between periodontal infection and CVD has been revealed in some epidemiologic studies, whereas other studies were unable to demonstrate such an association. A link between the two diseases may be explained by shared established or nonestablished risk factors. Future studies with extended control of confounding factors and intervention studies may add to the understanding of a possible relationship between the diseases. In some cases, IE is caused by dental plaque bacteria. Several studies are suggestive of oral bacteria causing respiratory infection. The pathogenesis and course of a number of other diseases including DM and rheumatoid arthritis have been associated wish periodontitis, but more research is necessary to elucidate possible pathogenic interactions.

Bronchopneumonia and oral health in hospitalized older patients. A pilot study

AIMS

To correlate microbial findings obtained by bronchoalveolar lavage in pneumonia patients with the clinical situation of the oral cavity.

METHOD

Quantitative aerobic and anaerobic cultures were carried out in 150 ml samples of bronchoalveolar lavage (BAL) obtained by means of an endoscope (Video Endoscope Pentax) inserted per os in the infected bronchus.

MATERIAL

Twenty consecutive patients with a tentative clinical diagnosis of bronchopneumonia in whom BAL was carried out for diagnostic purposes. A clinical evaluation of the oral health status (oral hygiene, caries, periodontal diseases) was subsequently carried out.

RESULTS

In seven edentulous subjects wearing complete dentures the culture of anaerobic microorganisms was negative or yielding less than 100 cfu/ml BAL. Two patients yielded high counts of S. aureus and one high counts of P. aeruginosa. In the 13 subjects with natural teeth left one showed high counts of Veillonella spp. (anaerobic) + P. aeruginosa, one high counts of Veillonella spp. + S. aureus, one high counts of P. aeruginosa + S. aureus and one high counts of E. coli. These four subjects showed poor oral hygiene, periodontal pockets and a BAL microflora consistent with periodontal pathology.

CONCLUSION

The results of this pilot study suggest that microorganisms of denture plaque or associated with periodontal diseases may give rise to aspiration pneumonia in susceptible individuals.

Intensified microbiological investigations in adult patients admitted to hospital with lower respiratory tract infections

The objective of this study was to investigate the diagnostic yield of a programme with intensified microbiological investigations in immunocompetent adult patients with lower respiratory tract infections (LRTI). Patients in the study group were included prospectively and consecutively from September 1st 1997 to May 31st 1998 and were compared with a control group from the preceding year. A total of 67 adult patients were included in the study group and they were compared with 122 adult patients in the control group. The study group underwent fibre-optic bronchoscopy (FOB) with bronchoalveolar lavage (BAL). Only 7% in the historic control group were discharged with an aetiological diagnosis of their infections; while the diagnostic yield in the study group increased to 51% of patients. In the study group the presence of new infiltrates on chest X-ray increased the detection of a microbiological aetiology from 37% with no infiltrates to 62% with infiltrates and recent antibiotic therapy reduced the detection of a microbiological cause of infection from 61% in 36 patients who had not received antibiotic therapy to 39% in 31 patients who had received recent antibiotic therapy prior to microbiological sampling. Patients in the study group with known aetiology had higher values of inflammatory markers than patients with unknown aetiology. For Streptococcus pneumoniae infection culture and urine antigen detection were complimentary depending on recent antibiotic therapy since seven of eight culture-positive patients had not received antibiotic therapy within 72 h prior to investigation, while all four patients positive for urine antigens from S. pneumoniae had received antibiotic therapy within 72 h of urine sampling. In conclusion intensified microbiologic investigations increase the diagnostic yield from 7% to 51% of patients in the study group with an aetiologic diagnosis. Routine FOB with BAL had no apparent effect on clinical outcome and seems only justified in selected patients with severe LRTI with infiltrates on chest X-ray and signs of severe inflammation where a high diagnostic yield is achieved.

Laboratory diagnosis of community-acquired lower respiratory tract infection

This article has focused on the evaluation of outpatients with lower respiratory illness. In large part, the need for microbiological work-up is host-dependent. Healthy patients usually do well, and laboratory data are often unnecessary. The abnormal host requires a different approach and, in general, the more compromised the host, the more aggressive the laboratory evaluation. A renal transplant patient with respiratory symptoms often follows the dictum that "common things happen commonly;" however, the clinician needs that extra level of assurance in this case. Some transplant patients may have respiratory illness caused by strongyloidiasis. Cystic fibrosis is another example of the need for a more comprehensive laboratory evaluation. Specialized selective media and additional susceptibility studies may be needed to evaluate isolates associated with exacerbation of symptoms in these patients. The clinical laboratory should be forewarned of any materials coming from invasive diagnostic techniques, so they can prepare and offer useful advice regarding specimens, transport, and follow-up. Microbiological laboratories are often most knowledgeable regarding what type of testing is appropriate. Direct communication with the laboratory is essential to assure the best patient care.

The role of atypical pathogens in community-acquired pneumonia

The atypical pathogens in community-acquired pneumonia traditionally have included Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella spp. Recent studies documenting their epidemiology and clinical characteristics have shown that these organisms are indistinguishable from the pneumococcus. Furthermore, therapy no longer depends on the specific bacterial cause of community-acquired pneumonia. Etiologic diagnosis is still difficult, although new methods are becoming available. This article focuses on these issues and on why the term atypical is no longer meaningful.

Clinical policy for the management and risk stratification of community-acquired pneumonia in adults in the emergency department

This clinical policy represents an approach that emphasizes key clinical information to determine the severity of CAP. By using this approach, a determination of whether the patient can be treated as an outpatient or inpatient may be made. Recommendations about the utility of ancillary studies and the use of antibiotics are also given. As more of the questions are answered through controlled studies, an evidence-based approach to this problem will become increasingly important in improving the outcome of patients with CAP.

Role of bronchoalveolar lavage in immunocompromised patients with pneumonia treated with a broad spectrum antibiotic and antifungal regimen

BACKGROUND

In a retrospective study the value of bronchoalveolar lavage (BAL) in the diagnosis of pneumonia was investigated in 95 immunocompromised patients suffering from haematological disorders and receiving a regimen of broad spectrum antibiotics and antifungal agents (BSAR).

METHODS

With the exception of four afebrile patients, all had fever, raised C reactive protein (CRP) levels, and new infiltrates visible on chest radiography. All patients underwent BAL to identify the organism causing the pneumonia and surveillance cultures were performed regularly for pathogens at different sites. Following classification of the isolates, patients with positive cultures were subdivided into two groups, pathogenic or contaminated. We investigated whether relevant pathogens were cultured only from the BAL fluid and whether they were susceptible to BSAR.

RESULTS

Although 77 of the 95 patients were thrombocytopenic, bleeding during BAL occurred in only 15% of all patients. Ten days after the procedure the fever improved in 88% of patients, radiographic findings improved in 71%, and CRP levels improved in 75% of patients; 22% of patients died within 28 days. Pathologically relevant isolates were found in 65% of all patients. Respiratory pathogens were detected only in the BAL fluid of 29 of the 95 patients (35% Gram positive species, 40% Gram negative species, 11% Mycobacterium, 11% fungi, and 3% cytomegalovirus). In 16 of these 29 patients (55%) the pathogens cultured only from the BAL fluid were resistant to treatment. Pathogens detected only in the BAL fluid were not susceptible to a standard broad spectrum antibiotic and antifungal regimen including teicoplanin, ceftriaxon, tobramycin, and amphotericin B in 12 of the 29 patients (41%).

CONCLUSIONS

Our data suggest that 12 patients were treated with broad spectrum antimicrobial agents which were not directed at the appropriate organism on in vitro sensitivity tests without BAL. BAL is a relatively safe procedure in the diagnosis of pneumonia, supplying important information in immunocompromised patients as well as in immunocompromised patients receiving BSAR.

Potential importance of Legionella species as etiologies in community acquired pneumonia (CAP)

Large percentages of patients with community acquired pneumonia (CAP) do not have a defined etiology. Between 1992-1993, 99 acute and convalescent sera were collected from patients with CAP of unknown etiology. The sera were tested using an indirect immunofluorescence antibody assay (IFA) against the following antigens: Legionella pneumophila, serogroups 3,5,6 and 7 and L. longbeachae, L. anisa, L. bozemanii and Legionella-Like Amoebal Pathogens (LLAP). A four-fold rise in titer to at least one of the antigens tested, was seen in 14% of patients; 8% to L. bozemanii, 4% to L. anisa, 2% to S. lyticum, 2% to LLAP 10 and 1% each to LLAP 1, 6 and 9. Two patients reacted to several antigens. These results indicate that other species of legionella may be important in the etiology of CAP. L. bozemanii was the organism identified in the majority of these infections. Better diagnostic studies i.e. cultures, serologies and urinary antigen testing, which recognize legionella isolates other than L. pneumophila serogroup 1 need to be developed.

Effect of macrolides as part of initial empiric therapy on medical outcomes for hospitalized patients with community-acquired pneumonia

OBJECTIVE

The goal of this study was to compare the outcomes of hospitalized patients receiving a nonpseudomonal third-generation cephalosporin with or without a macrolide for the treatment of community-acquired pneumonia (CAP).

BACKGROUND

The initial treatment of CAP is usually based on empirically selected antibiotic therapy. The need for coverage of atypical pathogens in hospitalized patients is widely debated, and regional variations may exist.

METHODS

All patients admitted to a community hospital or to a university hospital for 1 year who were aged > or =18 years and had a principal discharge diagnosis of pneumonia with no organism specified according to the International Classification of Diseases, Ninth Revision, Clinical Modification were evaluated. Each patient's medical chart was reviewed by a clinical pharmacist at each facility. The following information was collected for each patient using a standardized form: demographic characteristics, coexisting illnesses, length of hospital and intensive care unit stays, antibiotic regimens, length of parenteral and oral therapy, laboratory and radiographic findings (ie, blood urea nitrogen, glucose, hematocrit, sodium, PO2, pH, and pleural effusion), physical examination results, and mortality. Patients treated with a nonpseudomonal third-generation cephalosporin with or without a macrolide were included in this analysis. Categoric variables were compared using the chi-square test or the Fisher exact test, and continuous variables were compared using the Mann-Whitney U test. A P value < 0.05 was considered statistically significant.

RESULTS

A total of 213 patients met the entry criteria and were treated with a nonpseudomonal third-generation cephalosporin with (116 patients) or without (97 patients) a macrolide. The mean (+/- SD) age of the patients was 62.2+/-19.6 years; 47% were male. The most common comorbid conditions were chronic obstructive pulmonary disease, diabetes mellitus, congestive heart failure, and cerebrovascular accident (CVA). Of the 116 patients who received a macrolide, the majority (66%) received erythromycin. Other macrolides used were clarithromycin (19%) and oral azithromycin (15%). There were no statistical differences between patients who did and did not receive a macrolide in terms of comorbid illnesses, length of hospital stay (5.2+/-2.8 vs 5.2+/-3.4 days, respectively), length of intravenous antibiotic therapy (4.4+/-2.5 vs 4.1+/-2.3 days, respectively), or mortality (0.9% vs 3.1%, respectively; P = 0.333). The only difference between the groups was in age. Those patients who received a macrolide were significantly younger than those who received only a nonpseudomonal third-generation cephalosporin (57.4+/-19.2 years vs 67.9+/-18.5 years; P < 0.001). However, when age and severity of illness were taken into account, no difference existed between the patients who received a nonpseudomonal third-generation cephalosporin alone or in combination with a macrolide.

CONCLUSIONS

We concluded that the addition of a macrolide to a nonpseudomonal third-generation cephalosporin as initial therapy for the treatment of CAP may not be necessary. A randomized, prospective clinical trial comparing a nonpseudomonal third-generation cephalosporin alone and in combination with a macrolide is warranted.

Bacteremic and nonbacteremic pneumococcal pneumonia. A prospective study

We prospectively identified cases of pneumococcal pneumonia and used stringent criteria to stratify them into bacteremic and nonbacteremic cases. Although patients were distributed among racial groups in proportion to all patients seen at this medical center, the proportion of African-Americans with bacteremic disease was significantly increased. All patients had at least 1 underlying condition predisposing to pneumococcal infection, and most had several. Although the mean number of predisposing factors was greater among bacteremic patients than nonbacteremic patients, only alcohol ingestion was significantly more common. Nearly one-third of patients had substantial anemia (hemoglobin < or = 10 g/dL) on admission, which may have predisposed to infection. In the case of other laboratory abnormalities, such as albumin, creatinine, and bilirubin, it was difficult to determine which abnormality might have predisposed to pneumococcal infection and which might have resulted from it. The radiologic appearance was varied. Airspace consolidation and air bronchogram on chest X-ray were highly associated with bacteremic disease, as was the presence of pleural effusion. Although the Pneumonia Patient Outcomes Research Team (PORT) risk score was a predictor of mortality, it did not help to predict the presence of bacteremia in an individual case. Most patients who died in the first week in hospital were bacteremic, and a high PORT risk score with bacteremia reliably predicted a high likelihood of a fatal outcome. Eleven patients had extrapulmonary disease with meningitis, empyema, and septic arthritis predominating; all of these patients were bacteremic. The antibiotic susceptibility of our strains correlated well with those that have been reported in the United States during the years of this study. The use of numerous antibiotics of different classes in many patients, especially those who were the most ill, precluded analysis of outcome based on antibiotic therapy. Only 17 patients had been vaccinated. Since nearly all patients had conditions for which pneumococcal vaccine is recommended and more than one-third had been hospitalized in the preceding 6 months, the low rate of vaccination can be regarded as a missed opportunity to administer a potentially beneficial vaccine.

Mannose-binding lectin polymorphisms and susceptibility to infection in systemic lupus erythematosus

OBJECTIVE

To determine whether variant alleles in the coding portion of the mannose-binding lectin (MBL) gene are associated with increased susceptibility to systemic lupus erythematosus (SLE) and concomitant infections.

METHODS

MBL alleles and serum concentrations were determined by polymerase chain reaction and enzyme-linked immunosorbent assay, respectively, in 91 Danish patients with SLE and in 250 controls.

RESULTS

Homozygosity for MBL variant alleles was observed in 7.7% of the SLE patients compared with 2.8% of the controls (P = 0.06), while no difference was seen for heterozygosity (33.0% versus 34.4%). Homozygotes had an increased risk of acquiring serious infections compared with patients who were heterozygous or homozygous for the normal allele (odds ratio 8.6, 95% confidence interval 1.5-47.6, P = 0.01). The time interval from the diagnosis of SLE to the first infectious event was shorter (P = 0.017), and the annual number of infectious events was 4 times higher, among homozygotes (P = 0.00002). They were especially prone to acquire pneumonia (P = 0.00004). CONCLUSION; Homozygosity for MBL variant alleles may explain much of the increased risk of complicating infections seen in SLE patients. Additionally, it is a minor risk factor for acquiring SLE.

Diagnostic testing for community-acquired pneumonia

The microbial cause of community-acquired pneumonia can be identified by noninvasive means in the majority of cases, usually within a few days of presentation. The Gram stain and culture of a pretreatment sputum sample are the most useful tests, but have significant limitations. Methods for detecting pneumococcal antigen in respiratory secretions are particularly helpful in patients who have received antibiotics before evaluation. Testing for specific pathogens such as L. pneumophila, M. pneumoniae, or C. pneumoniae should be guided by clinical suspicion in individual circumstances. Invasive procedures are most helpful in patients suspected of having infection with opportunistic or resistant pathogens, and in those whose initial management has been unsuccessful.

Utility of blood cultures in community-acquired pneumonia requiring hospitalization: influence of antibiotic treatment before admission

It has been previously shown that antibiotics given before hospitalization significantly reduce the proportion of positive blood cultures in community-acquired pneumonia (CAP). The aim of this prospective study was to compare the utility and cost-benefits of blood cultures in patients, hospitalized for moderate CAP, who had or had not received antibiotic therapy prior to admission. During 1 year, 53 patients were included and separated into two groups: group 1 patients had not received antibiotic treatment prior to admission (n = 30), whereas group 2 patients had been treated with antibiotics (n = 23). Within the first 48 hours, a set of blood cultures was collected if the body temperature was higher than 38.5 degrees C or in the case of shaking chills. A total of 136 blood cultures was collected; 74 in group 1 and 62 in group 2. Bacteraemia was significantly more frequent in group 1 than in group 2, 5/30 patients vs. 0/23, respectively (P < 0.05). The cost of negative blood cultures was valued at 13,939.2 FF in group 1 and 13,164.8 FF in group 2, respectively 464.6 +/- 244.3 FF and 569.3 +/- 233.4 FF per patient (n.s.). Moreover, blood cultures were the method of diagnosis in only one of the five patients with bacteraemia and in no case did a positive blood-culture result influence the initial therapeutic regime. Thus, our results suggest a reduced clinical utility and cost-benefit of blood cultures in patients hospitalized for moderate CAP who have received an antibiotic treatment prior to admission.

Community-acquired pneumonia

Community-acquired pneumonia (CAP) is a significant cause of morbidity and mortality in all age groups, especially the elderly, which is a patient population that continues to grow. Recently the spectrum and clinical picture of pneumonia has been changing as a reflection of this aging population; this requires a reassessment of and a new approach to the patient with pneumonia. Currently, pneumonia patients are classified as having either community-acquired or hospital-acquired infection rather than typical versus atypical. Patients who have CAP are categorized by age, presence of a coexisting medical illness, and the severity of the pneumonia. The rationale behind categorizing patients is to stratify them in terms of mortality risk to help determine the location of therapy (e.g., outpatient, inpatient, intensive care unit) and focus the choice of initial antimicrobial therapy. Once the decision to hospitalize a patient with pneumonia is made, the next step is to decide on an appropriate diagnostic evaluation and antibiotic therapy. Both decisions have evolved over the last several years since the publication of the American Thoracic Society's CAP guidelines. The current approach to the diagnostic work-up of pneumonia stresses a limited role of diagnostic tests and procedures. The antimicrobial regimen has now evolved into one that is empiric in nature and based on the age of the patient, the presence of coexisting medical disease, and the overall severity of the pneumonia. This process is a dynamic once because bacterial resistance to commonly used antibiotics can further complicate the course of pneumonia therapy, but the impact of resistance on outcome is less clear. Resistance of Streptococcus pneumoniae to penicillin is a prime example of this growing problem, and adjustment to pneumonia therapy may be required. A difficult but not uncommon problem in pneumonia patients is slow recovery and delayed resolution of radiographic infiltrates. Factors that impact negatively on pneumonia resolution include advanced age and the presence of serious comorbid illnesses such as diabetes mellitus, renal disease, or chronic obstructive pulmonary disease. In addition, certain organism factors (e.g., intrinsic virulence) may interact with host factors and advanced age to delay pneumonia resolution. For example, 50% of patients with pneumococcal pneumonia have radiographic clearing at 5 weeks, and the majority clear within 2 to 3 months. Recent data demonstrate that radiographic resolution of CAP is most influenced by the number of lobes involved and the age of the patient. Radiographic clearance of CAP decreases by 20% per decade after age 20, and patients with multilobar infiltrates take longer to clear than those with unilobar disease. In general, when approaching slowly resolving infiltrates after pneumonia, bronchoscopic evaluation and lung biopsy are more likely to yield a specific diagnosis if the patient is a nonsmoker younger than 55 years old with multilobar disease. If the patients has either no identifiable factors associated with prolonged pneumonia resolution or the repeat chest radiograph at 1 month shows no appreciable change, further diagnostic testing is indicated. The route and duration of antibiotic therapy, another detail of the management of CAP patients that has changed recently, is complicated by the fact that the majority of patients with CAP have no pathogen identified. Therefore, in most instances the physician initiates empiric antibiotics on the basis of epidemiologic data. If an etiologic pathogen is identified (either initially or at a later time), then the antibiotic spectrum can be narrowed. When no pathogen is discovered, broad-spectrum empiric antibiotics are continued. (ABSTRACT TRUNCATED)

Pneumococcal community-acquired pneumonia in 148 hospitalized adult patients

In a previous prospective study, Streptococcus pneumoniae was identified as the causative agent in 148 (42.8%) of 346 adult patients hospitalized over the course of one year with community-acquired pneumonia (CAP) in the Soroka Medical Center, Beer-Sheva, Israel. The present study characterizes those cases in which Streptococcus pneumoniae was the only pathogen and those in which additional etiological agents were identified. Pneumococcal CAP was diagnosed by standard blood cultures or positive serological tests by one of two laboratory methods. In 100 (67.6%) patients, at least one other etiological agent of CAP was identified in addition to Streptococcus pneumoniae. Compared with patients who were not infected by Streptococcus pneumoniae, patients with Streptococcus pneumoniae CAP were older and had a higher rate of comorbidity (39.5% vs. 29.8%). Streptococcus pneumoniae CAP had a more severe clinical course and a higher mortality rate, especially when Streptococcus pneumoniae was the only pathogen. Community-acquired pneumonia due to Streptococcus pneumoniae only was more similar in its clinical manifestations to classic typical pneumococcal pneumonia. When an additional etiological agent was identified, the clinical characteristics could not be distinguished from those of atypical pneumonia. It is concluded that Streptococcus pneumoniae remains the principal cause of CAP in this region. The frequency of additional etiological agents of CAP and the difficulty in differentiating clinically between cases due to Streptococcus pneumoniae only and those due to Streptococcus pneumoniae plus other organisms necessitates initial empirical treatment that covers Streptococcus pneumoniae as well as other causative agents of atypical pneumonia.

Relationships between periodontal disease and bacterial pneumonia

Bacterial pneumonia is a prevalent and costly infection that is a significant cause of morbidity and mortality in patients of all ages. The continuing emergence of antibiotic-resistant bacteria (e.g., penicillin-resistant pneumococci) suggests that bacterial pneumonia will assume increasing importance in the coming years. Thus, knowledge of the pathogenesis of, and risk factors for, bacterial pneumonia is critical to the development of strategies for prevention and treatment of these infections. Bacterial pneumonia in adults is the result of aspiration of oropharyngeal flora into the lower respiratory tract and failure of host defense mechanisms to eliminate the contaminating bacteria, which multiply in the lung and cause infection. It is recognized that community-acquired pneumonia and lung abscesses can be the result of infection by anaerobic bacteria; dental plaque would seem to be a logical source of these bacteria, especially in patients with periodontal disease. It is also possible that patients with high risk for pneumonia, such as hospitalized patients and nursing home residents, are likely to pay less attention to personal hygiene than healthy patients. One important dimension of this personal neglect may be diminished attention to oral hygiene. Poor oral hygiene and periodontal disease may promote oropharyngeal colonization by potential respiratory pathogens (PRPs) including Enterobacteriaceae (Klebsiella pneumoniae, Escherichia coli, Enterobacter species, etc.), Pseudomonas aeruginosa, and Staphylococcus aureus. This paper provides the rationale for the development of this hypothesis especially as it pertains to mechanically ventilated intensive care unit patients and nursing home residents, two patient groups with a high risk for bacterial pneumonia.

High resolution CT findings in community-acquired pneumonia

PURPOSE

Our goal was to clarify the high resolution CT (HRCT) findings of community-acquired pneumonia based on pathologic findings and to make a differential diagnosis between bacterial and atypical pneumonias.

METHOD

This study evaluated 32 cases with community-acquired pneumonia, including 18 cases with bacterial pneumonia and 14 cases with atypical pneumonia [mycoplasma pneumonia (n = 12), chlamydia pneumonia (n = 1), and influenza viral pneumonia (n = 1)]. HRCT images in these cases were space consolidation, ground-glass attenuation, thickening of the bronchovascular bundle, and distribution of abnormal attenuation.

RESULTS

Bacterial pneumonia frequently showed air space consolidation with segmental distribution (72.2%) that tended to locate at the middle and outer zones of the lung. Atypical pneumonia frequently showed centrilobular shadow (64.3%), acinar shadow (71.4%), air space consolidation and ground-glass attenuation with lobular distribution (57.1 and 85.7%, respectively), and tendency of the lesions to distribute at the inner layer of the lung in addition to the middle and outer layers (85.7%).

CONCLUSION

Characteristic HRCT findings of both bacterial and atypical pneumonia were demonstrated. These HRCT features seemed to reflect pathologic findings and the manner of lesional progression. This information may support the appropriate antibiotic therapy in medical practice.

Community acquired, nursing home acquired and hospital acquired pneumonia: A five-year review of the clinical, bacteriological and radiological characteristics

PURPOSE

To assess the contemporary clinical, bacteriological and radiographic features of hospitalized patients with community acquired (ca), nursing home acquired (na) and hospital acquired pneumonia (ha) and to examine patient outcome.

PATIENTS AND METHODS

All hospital records of patients with pneumonia over a five-year period from April 1987 to March 1992 were reviewed retrospectively. Patients included in the study were all those with a diagnosis of pneumonia as identified by computer records of diagnostic codes at discharge; patients with a specific diagnosis of Pneumocystis carinii pneumonia were excluded. Of 74,435 discharges over the five-year period, 1782 patients met the inclusion criteria.

RESULTS

Charts of 1622 of the total 1782 cases were reviewed. Mean age was 64.4 years with 59.4% men and 40.6% women. Sixty-three per cent were ca, 28.5% were ha and 8.5% were na. A total of 1542 patients (95%) had at least one concomitant medical condition. Chest roentgenogram was abnormal in 97%. Common organisms isolated overall were Haemophilus influenzae (from 204 patients), Staphylococcus aureas (from 152 patients), Streptococcus pneumoniae (from 143 patients ), Escherichia coli (from 113 patients) and Pseudomonas aeruginosa (from 111 patients). H influenzae and S pneumoniae were most common in ca pneumonia, whereas S aureus and Gram-negative organisms were more common in the ha group and Gram-negative agents in the na group. One hundred and four patients developed complications. Fifteen per cent required intensive care unit admission. The average length of hospitalization in the ca and na groups was 17 days and in the ha group, 43 days. At time of discharge 1261 patients (78%) were cured or improved, and 361 patients (22%) died during the admission.

CONCLUSIONS

These results suggest that hospitalization for pneumonia in the 1990s is primarily for elderly patients with significant co-morbidity. Although microbiology appears unchanged compared with earlier reports, the contemporary population is significantly sicker than previous cohorts. This may account for the persistently high morbidity and mortality despite better or newer antibiotics.

Clinical utility of blood cultures in adult patients with community-acquired pneumonia without defined underlying risks

STUDY OBJECTIVE

We retrospectively examined the clinical utility of obtaining routine blood cultures before the administration of antibiotics in certain nonimmunosuppressed patients with community-acquired pneumonia (CAP) admitted to the hospital during 1991.

DESIGN

Retrospective review.

SETTING

Grady Memorial Hospital (a county hospital primarily serving inner-city Atlanta).

PATIENTS OR PARTICIPANTS

Hospital discharge diagnosis listings identified 1,250 adults ( > or = 18 years old) with pneumonia. From this group of patients, we selected patients admitted to the hospital with (1) respiratory symptoms and a lobar infiltrate on chest radiograph that were present at the time of hospital admission, (2) two or more sets of blood cultures obtained within 48 h of hospital admission, and (3) absence of defined risk factors: HIV-related illness, malignancy, recent chemotherapy, steroid therapy, sickle cell disease, nursing home residence, or hospital stays within the past 14 days.

MEASUREMENTS AND RESULTS

Five hundred seventeen patients (mean age, 52 years;: age range, 18 to 103 years) qualified. Of these 517 patients, 25 patients (4.8%) had growth in blood cultures considered contaminants while 34 (6.6%) had blood cultures positive for the following pathogens: 29 Streptococcus pneumoniae, 3 Haemophilus influenzae, and 1 Streptococcus pyogenes, 1 Escherichia coli. Antibiotic therapy was changed for 7 of the 34 patients with positive blood cultures (1.4% of study patients). Antibiotic regimens were altered in 48 additional patients based on sputum culture, poor clinical response, and allergic reactions.

CONCLUSIONS

Few blood cultures were positive for likely infecting organisms in adult patients with CAP without defined underlying risk factors. Furthermore, a total of $34,122 was spent on blood cultures at $66 per patient. In this carefully defined group of patients, blood cultures may have limited clinical utility and questionable cost-effectiveness.

Evaluation of the invasive techniques for diagnosing bacterial respiratory infections

Bacterial community-acquired respiratory infections are usually sustained by strains highly responsive to antibiotic therapy. Thus, the clinical approach is based on an empirical treatment and does not require the isolation of the causative pathogen and the determination of the bacterial susceptibility to antibiotics. On the other hand, Gram-negative bacteria, most commonly multidrug resistant, frequently affect immunocompromised and nosocomial patients and their identification in cultures is absolutely necessary for proper antibacterial treatment. To this aim, two conventional methods are used, i.e. the blood culture, which is positive only in 20% of pneumonia cases, and the sputum culture, which is not invasive but easily contaminated by oropharyngeal flora. Consequently, invasive techniques for sampling the pathologic specimen, such as the BAL and the PSB, performed with the help of fiberoptic bronchoscope, are needed. The diagnostic power and the limits of both these techniques are analyzed. Moreover, the opportunity to obtain quantitative cultures, which may discriminate between contamination and infection is considered.