Risk factors for adverse outcome in persons with pneumococcal pneumonia

Fever Is Associated with Reduced, Hypothermia with Increased Mortality in Septic Patients: A Meta-Analysis of Clinical Trials

Background

Sepsis is usually accompanied by changes of body temperature (T_b), but whether fever and hypothermia predict mortality equally or differently is not fully clarified. We aimed to find an association between T_b and mortality in septic patients with meta-analysis of clinical trials.

Methods

We searched the PubMed, EMBASE, and Cochrane Controlled Trials Registry databases (from inception to February 2016). Human studies reporting T_b and mortality of patients with sepsis were included in the analyses. Average T_b with SEM and mortality rate of septic patient groups were extracted by two authors independently.

Results

Forty-two studies reported T_b and mortality ratios in septic patients (n = 10,834). Pearson correlation analysis revealed weak negative linear correlation (R² = 0.2794) between T_b and mortality. With forest plot analysis, we found a 22.2% (CI, 19.2–25.5) mortality rate in septic patients with fever (T_b > 38.0°C), which was higher, 31.2% (CI, 25.7–37.3), in normothermic patients, and it was the highest, 47.3% (CI, 38.9–55.7), in hypothermic patients (T_b < 36.0°C). Meta-regression analysis showed strong negative linear correlation between T_b and mortality rate (regression coefficient: -0.4318; P < 0.001). Mean T_b of the patients was higher in the lowest mortality quartile than in the highest: 38.1°C (CI, 37.9–38.4) vs 37.1°C (CI, 36.7–37.4).

Conclusions

Deep T_b shows negative correlation with the clinical outcome in sepsis. Fever predicts lower, while hypothermia higher mortality rates compared with normal T_b. Septic patients with the lowest (< 25%) chance of mortality have higher T_b than those with the highest chance (> 75%).

Pseudomonas aeruginosa: breaking down barriers

Many bacterial pathogens have evolved ingenious ways to escape from the lung during pneumonia to cause bacteremia. Unfortunately, the clinical consequences of this spread to the bloodstream are frequently dire. It is therefore important to understand the molecular mechanisms used by pathogens to breach the lung barrier. We have recently shown that Pseudomonas aeruginosa, one of the leading causes of hospital-acquired pneumonia, utilizes the type III secretion system effector ExoS to intoxicate pulmonary epithelial cells. Injection of these cells leads to localized disruption of the pulmonary-vascular barrier and dissemination of P. aeruginosa to the bloodstream. We put these data in the context of previous studies to provide a holistic model of P. aeruginosa dissemination from the lung. Finally, we compare P. aeruginosa dissemination to that of other bacteria to highlight the complexity of bacterial pneumonia. Although respiratory pathogens use distinct and intricate strategies to escape from the lungs, a thorough understanding of these processes can lay the foundation for new therapeutic approaches for bacterial pneumonia.

Lung and pleural fibrosis in asbestos-exposed workers: a risk factor for pneumonia mortality

Lungs exposed to occupational dust may be especially vulnerable to fatal infections. We followed up asbestos-exposed workers (n=590) originally screened for lung cancer with computed tomography and scored for pleuropulmonary fibrosis. We checked these workers' influenza and pneumonia mortality data (ICD-10 codes J10–J18) in the national register. In total, 191 deaths, including 43 deaths from infectious pneumonia, occurred in 6158 person-years of follow-up (mean follow-up time 10·44 years). ‘Some interstitial fibrosis’ [hazard ratio (HR) 2·26, 95% confidence interval (CI) 0·98–5·19, P=0·06] and ‘definite interstitial fibrosis’ (HR 3·70, 95% CI 1·22–11·23, P=0·02) were associated with an increased risk of death from pneumonia compared to no fibrosis. Asbestosis patients, i.e. those with both asbestos exposure and lung fibrosis, therefore appear to be particularly at risk for death from pneumonia. These patients should be vaccinated against influenza and Pneumococcus.

The role of the macrophage in lung disease mediated by bacteria

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

Time to positivity in blood cultures of adults with Streptococcus pneumoniae bacteremia

BACKGROUND

previous studies have established that bacterial blood concentration is related with clinical outcome. Time to positivity of blood cultures (TTP) has relationship with bacterial blood concentration and could be related with prognosis. As there is scarce information about the usefulness of TTP, we study the relationship of TTP with clinical parameters in patients with Streptococcus pneumoniae bacteremia.

METHODS

TTP of all cases of Streptococcus pneumoniae bacteremia, detected between January 1995 and December 2004 using the BacT/Alert automated blood culture system in a teaching community hospital was analyzed. When multiple cultures were positive only the shortest TTP was selected for the analysis.

RESULTS

in the study period 105 patients with Streptococcus pneumoniae bacteremia were detected. Median TTP was 14.1 hours (range 1.2 h to 127 h). Immunosuppressed patients (n = 5), patients with confusion (n = 19), severe sepsis or shock at the time of blood culture extraction (n = 12), those with a diagnosis of meningitis (n = 7) and those admitted to the ICU (n = 14) had lower TTP. Patients with TTP in the first quartile were more frequently hospitalized, admitted to the ICU, had meningitis, a non-pneumonic origin of the bacteremia, and a higher number of positive blood cultures than patients with TTP in the fourth quartile. None of the patients with TTP in the 90th decile had any of these factors associated with shorter TTP, and eight out of ten patients with TTP in the 10th decile had at least one of these factors. The number of positive blood cultures had an inverse correlation with TTP, suggesting a relationship of TTP with bacterial blood concentration.

CONCLUSION

Our data support the relationship of TTP with several clinical parameters in patients with Streptococcus pneumoniae bacteremia, and its potential usefulness as a surrogate marker of outcome.

Severe community-acquired pneumonia: use of intensive care services and evaluation of American and British Thoracic Society Diagnostic criteria

Despite careful evaluation of changes in hospital care for community-acquired pneumonia (CAP), little is known about intensive care unit (ICU) use in the treatment of this disease. There are criteria that define CAP as "severe," but evaluation of their predictive value is limited. We compared characteristics, course, and outcome of inpatients who did (n = 170) and did not (n = 1,169) receive ICU care in the Pneumonia Patient Outcomes Research Team prospective cohort. We also assessed the predictive characteristics of four prediction rules (the original and revised American Thoracic Society criteria, the British Thoracic Society criteria, and the Pneumonia Severity Index [PSI]) for ICU admission, mechanical ventilation, medical complications, and death (as proxies for severe CAP). ICU patients were more likely to be admitted from home and had more comorbid conditions. Reasons for ICU admission included respiratory failure (57%), hemodynamic monitoring (32%), and shock (16%). ICU patients incurred longer hospital stays (23.2 vs. 9.1 days, p < 0.001), higher hospital costs (21,144 dollars vs. 5,785 dollars, p < 0.001), more nonpulmonary organ dysfunction, and higher hospital mortality (18.2 vs. 5.0%, p < 0.001). Although ICU patients were sicker, 27% were of low risk (PSI Risk Classes I-III). Severity-adjusted ICU admission rates varied across institutions, but mechanical ventilation rates did not. The revised American Thoracic Society criteria rule was the best discriminator of ICU admission and mechanical ventilation (area under the receiver operating characteristic curve, 0.68 and 0.74, respectively) but none of the prediction rules were particularly good. The PSI was the best predictor of medical complications and death (area under the receiver operating characteristic curve, 0.65 and 0.75, respectively), but again, none of the prediction rules were particularly good. In conclusion, ICU use for CAP is common and expensive but admission rates are variable. Clinical prediction rules for severe CAP do not appear adequately robust to guide clinical care at the current time.

Pneumococcal vaccine for asthma

BACKGROUND

Infection with Streptococcus pneumoniae is an important cause of pneumonia and other serious illnesses, particularly amongst those with certain high-risk medical conditions such as asthma. Although pneumococcal vaccine is routinely advocated for people with asthma, there is uncertainty about the evidence base that underpins this recommendation.

OBJECTIVES

To determine the efficacy of pneumococcal vaccine in reducing mortality or morbidity from pneumococcal disease in asthmatics.

SEARCH STRATEGY

Randomised controlled trials were identified using the Cochrane Airways Group's register derived from MEDLINE, EMBASE, and CINAHL electronic databases and hand searched respiratory journals and meeting abstracts.

SELECTION CRITERIA

Randomised controlled trials, with or without blinding, in which pneumococcal vaccine has been compared with placebo or no treatment in people with clinician diagnosed asthma.

DATA COLLECTION AND ANALYSIS

Two reviewers independently reviewed all abstracts and full papers of all articles of potential relevance were retrieved. Methodological quality was rated using the Cochrane approach and the Jadad rating scale. Data extraction was performed by one reviewer and checked independently by a second. We planned to perform quantitative analyses of outcomes on an intention-to-treat basis, where possible.

MAIN RESULTS

Of the three papers retrieved, only one satisfied the inclusion criteria and the methodological quality of this study was low (unblinded and inadequate allocation concealment). None of the data could be aggregated in a meta-analysis. Comparisons in a sub-set of 30 asthmatic children prone to recurrent episodes of otitis media, showed that pneumococcal vaccination decreased the incidence of acute asthma exacerbations from 10 to 7 (per child per year).

REVIEWER'S CONCLUSIONS

This review found very limited evidence to support the routine use of pneumococcal vaccine in people with asthma. A randomised trial of vaccine efficacy in children and adults with asthma is needed.

Invasive pneumococcal disease in the immunocompromised host

A normal constituent of the human upper respiratory flora, Streptococcus pneumoniae also produces respiratory tract infections that progress to invasive disease at high rates in specific risk groups. The individual factors that contribute to the development of invasive pneumococcal disease in this distinct minority of persons, include immune (both specific and innate), genetic, and environmental elements. Specific defects in host responses may involve age, deficiencies in levels of antibodies and complement factors, and splenic dysfunction. Combinations of these immune defects contribute to the increased rates of invasive pneumococcal disease in patients with sickle cell disease, nephrotic syndrome, neoplasms, and underlying medical conditions such as diabetes and alcoholic liver disease. The number of risk factors are greatest and the rates of invasive disease are highest in patients with HIV-1 infection, which has emerged as a major risk factor for serious S. pneumoniae infection worldwide.

Clinical characteristics and outcome of children with pneumonia attributable to penicillin-susceptible and penicillin-nonsusceptible Streptococcus pneumoniae

OBJECTIVE

To compare the clinical characteristics, treatment, and outcome of pediatric patients with pneumonia attributable to isolates of Streptococcus pneumoniae that were either susceptible or nonsusceptible to penicillin.

DESIGN

Multicenter, retrospective study.

SETTING

Eight children's hospitals in the United States.

PARTICIPANTS

Two hundred fifty-four children with pneumococcal pneumonia identified from patients enrolled in the United States Pediatric Multicenter Pneumococcal Surveillance Study during the 3-year period from September 1, 1993 to August 31, 1996.

OUTCOME MEASURES

Demographic and clinical variables including necessity for and duration of hospitalization, frequency of chest tube placement, antimicrobial therapy, susceptibility of isolates, and clinical outcome.

RESULTS

There were 257 episodes of pneumococcal pneumonia that occurred in 254 patients. Of the 257 isolates, 22 (9%) were intermediate and 14 (6%) were resistant to penicillin; 7 (3%) were intermediate to ceftriaxone and 5 (2%) were resistant to ceftriaxone. There were no differences noted in the clinical presentation of the patients with susceptible versus nonsusceptible isolates. Twenty-nine percent of the patients had a pleural effusion. The 189 (74%) hospitalized patients were more likely to have an underlying illness, multiple lung lobe involvement, and the presence of a pleural effusion than nonhospitalized patients. Fifty-two of 72 hospitalized patients with pleural effusions had a chest tube placed, and 27 subsequently underwent a decortication drainage procedure. Eighty percent of the patients treated as outpatients and 48% of the inpatients received a parenteral second or third generation cephalosporin followed by a course of an oral antimicrobial agent. Two hundred forty-eight of the patients (97.6%) had a good response to therapy. Six patients died; however, only 1 of the deaths was related to the pneumococcal infection.

CONCLUSION

The clinical presentation and outcome of therapy did not differ significantly between patients with penicillin-susceptible versus those with nonsusceptible isolates of S pneumoniae. Hospitalized patients were more likely to have underlying illnesses, multiple lobe involvement, and the presence of pleural effusions than patients who did not require hospitalization. In otherwise normal patients with pneumonia attributable to penicillin-resistant pneumococcal isolates, therapy with standard beta-lactam agents is effective.

Bacteraemic pneumococcal infections in Southern Sweden 1981-96: trends in incidence, mortality, age-distribution, serogroups and penicillin-resistance

In a survey of pneumococcal blood isolates from patients in Southern Sweden, 560 isolates were found between 1981 and 1996. Between these years, the incidence of pneumococcal bacteraemia increased from 5.2 to 15.2/100,000/y. The eight most common serogroups/types (14, 7, 9, 6, 23, 3, 4 and 19) accounted for > 75% of the isolates, and 96.4% of the isolates were of serogroups/types represented in the present vaccine. A male preponderance (1.17:1) was noted, and the men were younger than the women (mean 57 vs 63 y of age; p < 0.05). The overall case-fatality rate during the period was 19%. Seven isolates with reduced susceptibility to penicillin were noted, all from 1991 to 1996. The increasing incidence of pneumococcal bacteraemia could not be explained by any of the following factors; age or sex of the patients, changes in prevailing serogroups/types, variations in vaccine use, emergence of penicillin-resistance, more liberal indications for blood cultures or improved culture methods.

Performance measurement in pneumonia care: beyond report cards

OBJECTIVE

To compare the medical management of bacteremic pneumococcal pneumonia at a university-based and a community-based teaching hospital and evaluate strategies for performance measurement and subsequent improvement.

DESIGN

We conducted a retrospective cohort study involving a 450-bed university hospital in the inner city and a 400-bed private hospital in a rural community.

MATERIAL AND METHODS

The medical records of all adults with bacteremic pneumococcal pneumonia admitted to a university and a community hospital during a 5-year period were reviewed. Information about patient age, sex, underlying medical condition, severity of disease, health-care insurance, management, and outcome was collected and analyzed.

RESULTS

Patients at the two hospitals were similar in underlying illnesses and severity of disease. In comparison with the community hospital, resource expenditure was greater at the university hospital, where all 11 identified diagnostic measures and treatment resources were used more often. This difference was statistically significant for sputum cultures, all cultures, and lumbar punctures. Despite the greater intensity of care, in-hospital mortality was higher at the university hospital (26%) than at the community hospital (12%) (P>0.1).

CONCLUSION

The outcome of bacteremic pneumococcal pneumonia did not differ significantly at a university hospital in comparison with a community teaching hospital, even though resource expenditure at the university hospital was greater. Our findings suggest that hospital "report cards" based solely on outcome comparisons provide inadequate information. In contrast, examination of variations in profiles of resource utilization can detect important differences in hospitals and can be used to guide continuous quality improvement efforts and ultimately improve hospital care.