María Luisa Briones

Assessment of Analysis of Urinary Pneumococcal Antigen by Immunochromatography for Etiologic Diagnosis of Community-Acquired Pneumonia in Adults

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

Accuracy of PaO2/FiO2 calculated from SpO2 for severity assessment in ED patients with pneumonia

Assessment of oxygenation in patients with community‐acquired pneumonia is critical for treatment. The accuracy of percutaneous oxygen saturation (SpO2) determined by pulse oximetry is uncertain, and it has limited value in patients receiving supplemental oxygen. We hypothesized that calculation of partial arterial oxygen concentration/inspired oxygen faction (PaO2/FiO2) from SpO2 by the Ellis or Rice equations might adequately correlate with PaO2/FiO2 measured by arterial blood gases.

Is it possible to predict which patients with mild pneumonias will develop hypoxemia

Usually, mortality due to mild community-acquired pneumonias (CAP) (Pneumonia severity index (PSI) classes I-III) is low (<3%), but the appearance of hypoxemia significantly increases mortality. Our aim was to determine the clinical parameters associated with risk factors of developing hypoxemia in subjects with mild CAP (PSI I-III) and the clinical outcomes of the hypoxemic group. We analyzed clinical characteristics and the outcomes of patients with mild CAP and hypoxemia (PaO2/FiO2<300), in a prospective, multicenter cohort study of 1195 patients. Mild pneumonias (PSI I-III) were found in 645 cases (53.9%), of which 217 (33.6%) presented hypoxemia according to a PaO2/FiO2<300. Patients with PaO2/FiO2<300 required more ICU admissions, mechanical ventilation, and developed septic shock than other PSI I-III patients. The clinical parameters associated with hypoxemia were: COPD, bilateral chest X-ray involvement, and hypoalbuminemia. We conclude that patients with COPD, those with bilateral chest X-ray involvement, or hypoalbuminemia were significantly more likely to have hypoxemia in mild CAP. Hypoxemic patients with low-risk pneumonia have worse clinical outcomes, including more ICU admission, need for mechanical ventilation and presence of septic shock than non-hypoxemic low-risk patients.

Does prolonged onset of symptoms have a prognostic significance in community-acquired pneumonia?

Severity assessment is made at the time of the initial clinical presentation in patients with community‐acquired pneumonia (CAP). It is unclear how the gap between time of presentation and duration of symptoms onset may impact clinical outcomes. Here we evaluate the association of prolonged onset of symptoms (POS) and the impact on clinical outcomes among hospitalized patients with CAP.

The potential role of 13-valent pneumococcal conjugate vaccine in preventing respiratory complications in bacteraemic pneumococcal community-acquired pneumonia.

INTRODUCTION Pneumococcal 13-valent vaccine (PCV-13) has a potential role in preventing bacteraemic pneumococcal pneumonia and its complications, but little is known about its ability to specifically prevent respiratory complications. Our aim were to analyse the pneumococcal serotypes associated with the development of respiratory complications and the potential role of PCV-13 in preventing respiratory complications in bacteraemic pneumococcal pneumonia. MATERIAL AND METHODS We analysed demographic characteristics, comorbidities, antibiotic resistances and the outcomes of a cohort of 65 vaccine-naïve bacteraemic pneumococcal pneumonias, stratified by the pneumococcal serotypes included in PCV13 vs. those not included. Complications were clustered as follows: respiratory complications (hypoxemic respiratory failure; mechanical ventilation), systemic complications (septic shock; multiorgan failure), suppurative complications (empyema; pleural effusion; lung abscess). RESULTS From a population of 65 CAP-SP, 47.7% of the isolates belonged to PCV-13 serotypes group. No differences in comorbidities or clinical manifestations were found between groups. With regard to biochemical parameters, we found more profound hypoxemia levels in PCV-13 serotypes group comparing to non-vaccine group [PaO2/FiO2 209 (63) vs. 268 (57); p=0.007]. Global complications were identified in 69.2% (45 patients), and the most frequent were respiratory complications, found in 47.7%. Respiratory complications were detected more frequently in PCV-13 groups compared to non-vaccine groups (61.3% vs. 35.3%; p=0.036). Overall 30-day mortality was 30.8%. Mortality was similar between both groups (25.8% vs. 35.3%; p=0.408). CONCLUSIONS Pneumococcal 13-valent conjugate vaccine includes the serotypes which cause more respiratory complications in our series; these serotypes were not associated with higher mortality in our series. PCV-13 may have a potential role in preventing respiratory complications due to bacteraemic pneumonoccal pneumonia.

Survival benefit of beta-lactam plus macrolide combined therapy versus beta-lactam plus quinolones in hospitalized community-acquired pneumonia

Background: Guidelines do not state a specific advantage regarding the addition of macrolides or quinolones to beta-lactams in empirical combined antibiotic therapy. But little is known if there exists a survival benefit of the different regimes. We aim to evaluate the impact in mortality of two different guidelines-recommended combined antibiotic therapies. Methods: We stratified patients from a prospective multicenter cohort according to the use of combined antibiotic treatment [beta-lactam plus macrolide (B+M) or beta-lactam plus quinolones (B+Q)]. Demographic, clinical, radiographic, microbiologic and complication characteristics were analyzed. Outcomes were analyzed performing a multivariate analysis using the different antibiotic combinations as the dependent variable. Results: From an initial population of 2,013 patients, 758 (37.6%) were treated with combination therapy: B+M, 575 (75.9%); B+Q 183 (24.1%). Comorbities were more frequent in patients treated with B+Q but this was not confirmed by multivariate analysis. B+M showed a protective effect regarding the development of acute kidney injury (OR 0.51, 95%CI 0.28-0.93) and ICU admission (OR 0.43, 95%CI 0.22-0.85). Mortality was significantly higher in B+Q group (11.6 vs 4.6, p Conclusions: Empiric combination antibiotic therapy with beta-lactams plus macrolides is associated with better survival than beta-lactam plus quinolones in CAP. Randomized control trials are needed to confirm this finding.

Differential Characteristics of Patients With Mild Acute Respiratory Distress Syndrome Due to Community-Acquired Pneumonia Admitted to ICU

Aims: To determine the characteristics of patients with community-acquired pneumonia and mild acute respiratory distress syndrome (CAP-mild ARDS) who require ICU admission. Methods: Analysis of demographic characteristics, comorbidities, etiology and outcomes of patients with CAP-mild ARDS admitted to ICU comparing to those who did not. X2, t student and logistic regression were used to compare both groups. Results: In a series of 1314 CAP patients, 164 (12.5%) showed mild ARDS at admission, of whom 25% (41 cases) were admitted to ICU. ICU patients were younger [57.5 (16) vs. 68.7 (15.4) years, p<0.01], and had a lower duration of symptoms [3.4 (1.9) vs. 6.5 (6) days, p<0.01] than no ICU patients. Pneumonia severity was higher in ICU group (PSI V: 39% vs. 17.1%; p=0.004). Multivariate analysis showed that age <65 years (OR 9.79, 95%CI 3.13-30.68), septic shock (OR 7.76, 95%CI 2.36-25.50), and PSI V (OR 7.28, 95%CI 2.16-24.56) were associated with ICU admission in CAP-mild ARDS patients; they showed a longer length of stay (LOS) [27 (28.6) vs. 10.6 (6) days, p<0.01] and more complications compared to those that were treated in a general ward (100% vs. 4.9%, p<0.01). Mortality was higher in ICU CAP mild-ARDS group but not statistically significant (17.1% vs. 7.3%, p= 0.068). Conclusions: 1-In our series, 25% of patients with CAP-mild ARDS required ICU admission. 2- Age <65 years, the presence of septic shock, and pneumonia severity were factors that determine ICU admission of CAP-mild ARDS patients in our series. 3-Patients with CAP-mild ARDS and ICU admission showed more complications and longer LOS without differences in mortality.