Bacteremic Community-acquired Pneumonia Research Articles

Community-Acquired Pneumonia Incidence in Adults Aged 18 Years and Older in Goto City, Japan: A Prospective Population-Based Study

Community-Acquired Pneumonia Incidence in Adults Aged 18 Years and Older in Goto City, Japan: A Prospective Population-Based Study

Qualification and Clinical Validation of an Immunodiagnostic Assay for Detecting 11 Additional Streptococcus pneumoniae Serotype-specific Polysaccharides in Human Urine.

BackgroundIdentifying Streptococcus pneumoniae serotypes by urinary antigen detection (UAD) assay is the most sensitive way to evaluate the epidemiology of nonbacteremic community-acquired pneumonia (CAP). We first described a UAD assay to detect the S. pneumoniae serotypes 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, and 23F, covered by the licensed 13-valent S. pneumoniae conjugate vaccine. To assess the substantial remaining pneumococcal disease burden after introduction of several pneumococcal vaccines, a UAD-2 assay was developed to detect 11 additional serotypes (2, 8, 9N, 10A, 11A, 12F, 15B, 17F, 20, 22F, and 33F) in individuals with radiographically confirmed CAP.MethodsThe specificity of the UAD-2 assay was achieved by capturing pneumococcal polysaccharides with serotype-specific monoclonal antibodies, using Luminex technology. Assay qualification was used to assess accuracy, precision, and sample linearity. Serotype positivity was based on cutoffs determined by nonparametric statistical evaluation of urine samples from individuals without pneumococcal disease. The sensitivity and specificity of the positivity cutoffs were assessed in a clinical validation, using urine samples obtained from a large study that measured the proportion of radiographically confirmed CAP caused by S. pneumoniae serotypes in hospitalized US adults.ResultsThe UAD-2 assay was shown to be specific and reproducible. Clinical validation demonstrated assay sensitivity and specificity of 92.2% and 95.9% against a reference standard of bacteremic pneumonia. In addition, the UAD-2 assay identified a S. pneumoniae serotype in 3.72% of nonbacteremic CAP cases obtained from hospitalized US adults. When combined with bacteremic CAP cases, the proportion of pneumonias with a UAD-2 serotype was 4.33%.ConclusionsThe qualified/clinically validated UAD-2 method has applicability in understanding the epidemiology of nonbacteremic S. pneumoniae CAP and for assessing the efficacy of future pneumococcal conjugate vaccines that are under development.

Rate and Predictors of Bacteremia in Afebrile Community-Acquired Pneumonia

Although blood cultures (BCs) are the "gold standard" for detecting bacteremia, the utility of BCs in patients with community-acquired pneumonia (CAP) is controversial. This study describes the proportion of patients with CAP and afebrile bacteremia and identifies the clinical characteristics predicting the necessity for BCs in patients who are afebrile. Bacteremia rates were determined in 4,349 patients with CAP enrolled in the multinational cohort study The Competence Network of Community-Acquired Pneumonia (CAPNETZ) and stratified by presence of fever at first patient contact. Independent predictors of bacteremia in patients who were afebrile were determined using logistic regression analysis. Bacteremic pneumonia was present in 190 of 2,116 patients who were febrile (8.9%), 101 of 2,149 patients who were afebrile (4.7%), and one of 23 patients with hypothermia (4.3%). Bacteremia rates increased with the CURB-65 score from 3.5%in patients with CURB-65 score of 0 to 17.1%in patients with CURB-65 score of 4. Patients with afebrile bacteremia exhibited the highest 28-day mortality rate (9.9%). Positive pneumococcal urinary antigen test (adjusted OR [AOR], 4.6; 95%CI, 2.6-8.2), C-reactive protein level > 200mg/L (AOR, 3.1; 95%CI, 1.9-5.2), and BUN level≥ 30mg/dL (AOR, 3.1; 95%CI, 1.9-5.3) were independent positive predictors, and antibiotic pretreatment (AOR, 0.3; 95%CI, 0.1-0.6) was an independent negative predictor of bacteremia in patients who were afebrile. A relevant proportion of patients with bacteremic CAP was afebrile. These patients had an increased mortality rate compared with patients with febrile bacteremia or nonbacteremic pneumonia. Therefore, the relevance of fever as an indicator for BC necessity merits reconsideration.

Antibiotic de-escalation therapy in patients with community-acquired nonbacteremic pneumococcal pneumonia.

Background De-escalation therapy is recommended as an effective antibiotic treatment strategy for several infectious diseases. While there is limited evidence supporting its clinical and cost-effective outcomes in patients with community-acquired bacteremic pneumonia, there is no evidence in patients with nonbacteremic pneumonia. Objective This study aimed to evaluate the antibiotic costs in patients who did and did not receive de-escalation therapy, based on the 2017 Japanese guidelines for the management of community-acquired nonbacteremic pneumococcal pneumonia of the Japanese Respiratory Society (JRS). Setting Kobeuniversity hospital, Japan. Methods A retrospective case series review including antibiotic use and length of hospital stay was conducted using the medical records from April 2008 to May 2019 at a university hospital in Japan. Main outcome measure Impact of antibiotic de-escalation therapy on the antibiotic costs. Results Among 55 patients who were eligible, the treating physicians de-escalated antibiotics in 28 (51%). The differences in the median length of hospital stay and the incidence of adverse drug reactions between the two groups were not statistically significant (p = 0.67 and 1.0, respectively). However, the median total antibiotic cost per infected patient in the de-escalated group was significantly lower than that in the non-de-escalated group [$269.8 ($195-$389) vs. $420.5 ($221-$799), p = 0.048]. Conclusion Antibiotic de-escalation based on the 2017 JRS guidelines leads to a reduction in total antibiotic costs for the management of community-acquired nonbacteremic pneumococcal pneumonia.

244. Development, Qualification, and Clinical Validation of an Immunodiagnostic assay for the Detection of 11 Additional S. pneumoniae Serotype-Specific Polysaccharides in Human Urine

BackgroundIdentifying Streptococcus pneumoniae (Sp) serotypes by urinary antigen detection assay (UAD) is the most sensitive and specific way to evaluate the changing epidemiology of non-bacteremic community-acquired pneumonia (CAP) and efficacy of pneumococcal vaccines. We first described an UAD to detect the Sp serotypes 1,-3,-4,-5,-6A,-6B,-7F,-9V,-14,-18C,-19A,-19F,-23F covered by the 13-valent Sp conjugate vaccine PCV13. To assess the pneumococcal disease burden of additional serotypes, a UAD-2 assay was developed to diagnose 11 additional Sp serotypes (-2,-8,-9N,-10A,-11A,-12F,-15B,-17F,-20,-22F,-33F).MethodsUAD-2 specificity was achieved by capturing highly purified pneumococcal polysaccharides with serotype-specific monoclonal antibodies using Luminex technology. Assay qualification assessed accuracy, precision, and sample linearity. Serotype positivity was based on cutoffs determined by non-parametric statistical evaluation of urine samples from individuals without pneumococcal disease. Clinical sensitivity and specificity of the positivity cutoffs were assessed in a clinical validation.ResultsThe UAD-2 was shown to be specific and reproducible. Clinical validation using urine samples from invasive disease patients demonstrated assay sensitivity and specificity of 92.2% and 95.9%, respectively compared with a gold standard of isolating and typing (by Quellung) Sp bacteria from patient samples. Analysis of 11,087 CAP patients showed a UAD-2 and UAD-1 serotype prevalence of 4.33% and 4.60%, respectively (bacteremic and non-bacteremic CAP combined).ConclusionThe qualified/clinically validated UAD-2 method has applicability in understanding the epidemiology of nonbacteremic Sp CAP as well as assessing vaccine efficacy of future pneumococcal conjugate vaccines.Disclosures All authors: No reported disclosures.

Bacteremic Community-Acquired Pneumonia in Ethiopian Children: Etiology, Antibiotic Resistance, Risk Factors, and Clinical Outcome.

BackgroundCommunity-acquired pneumonia (CAP) remains a leading cause of morbidity and mortality. We sought to determine the magnitude, etiology, and risk factors of CAP in children 5 years after introduction of pneumococcal conjugate vaccine (PCV) 10 in Ethiopia.MethodsWe conducted a prospective observational study on the bacterial etiology and risk factors of CAP among children aged 0–15 years in 2 pediatric emergency departments in Addis Ababa, Ethiopia. Blood culture, antibiotic susceptibility testing, and amplification of pneumococcal lytA and cpsB genes were performed. Serotypes of Streptococcus pneumoniae were determined by Quellung reaction and sequencing the cpsB gene.ResultsOut of 643 eligible children, 549 were enrolled. The prevalence of bacteremic pneumonia was 5.6%. Staphylococcus aureus (26.5%) was the predominant pathogenic species, followed by Enterococcus faecium (11.8%), Escherichia coli (11.8%), and Klebsiella pneumoniae (11.8%). In univariate analysis, parental smoking and nonvaccination with PCV10 were associated with bacteremic CAP. In multivariable analysis, female sex (adjusted odds ratio [aOR], 2.3; 95% confidence interval [CI], 1.1–4.9), weight-for-age z-score (WAZ) <–2 SDs (aOR, 2.2; 95% CI, 1.1–4.8), and lower chest indrawing (aOR, 0.44; 95% CI, 0.2–0.95) were independently associated with bacteremic CAP. The overall in-hospital case fatality rate was 2.37% (13/549), and WAZ <–3 SDs (OR, 13.5; 95% CI, 3.95–46.12) was associated with mortality.ConclusionsFive years after the introduction of PCV10 in Ethiopia, S. aureus was the main cause of bacteremic CAP in children, the contribution of S. pneumoniae was low, and there was a high level of antibiotic resistance among isolates.

1460. Community-Acquired Bacteremic Pneumonia in Post-pneumococcal Vaccination Era in a Pediatric Hospital

BackgroundFrom January 2012 PCV13 was introduced into immunization program in Argentina, 2 + 1 schedule for <2 years. The aims of this study were to describe epidemiological-clinical pattern of community-acquired bacteremic pneumonia (CABP) in the post-vaccination period and the risks factors of CABP occurrence, complications and lethality.MethodsCross-sectional study was performed in children with CABP diagnosis, hospitalized in Ricardo Gutierrez Children’s Hospital from January 2012 to December 2017.ResultsA total of 135 CABP cases were included; 63% male; 31.1% <2 years; 75% of <5 years received PCV13; 30.4% had underlying diseases. The pathogens isolated were (n = 136): Streptococcus pneumoniae (Sp) 44.9% (all susceptible to Penicillin), Staphylococcus aureus (Sa) 37.5% (Methicillin-Resistant 90.2%), Haemophilus influenzae (Hi) 15.4% (33.3% nontypable Hi), Β-hemolytic Streptococci Group A 1.5% and Neisseria meningitidis 0.7%. Seventy-one percent of cases had complications (pleural effusion 63%, necrotizing pneumonia 11.1%, pneumothorax 8.1%, lung abscess 3.7%, atelectasis 0.7%). Other clinical manifestations combined with CABP were: sepsis 20%, cellulitis/abscess 9.6%, arthritis 6.7%, meningitis 5.9% and osteomyelitis 3.7%. Condensation was the predominant radiological pattern for all agents in 88.1%. Lethality rate was 3%. Sp was more associated with age ≥24 months [OR 2.78 (1.18–6.64)] and Hi was more associated with age <24 months [OR 4.76 (1.62–14.31)]. Complications were significantly higher among Sa pneumonia cases. Children with CABP and sepsis or arthritis had higher lethality [OR 13.38 (1.14–355.45) and OR 17.71 (1.46–223.73)], respectively.ConclusionAfter PCV13 introduction Sp was still the most common organism causing CABP, mainly in ≥24 months of age. Sa followed in frequency with high morbility. CABP combined with other clinical manifestations were more associated with lethality.Disclosures All authors: No reported disclosures.

Macrolide therapy is associated with lower mortality in community-acquired bacteraemic pneumonia.

Community-acquired pneumonia (CAP) has a potential complication of bacteremia. The objective of this study was to define the clinical outcomes of patients with CAP and bacteremia treated with and without a macrolide. Secondary analysis of the Community-Acquired Pneumonia Organization database of hospitalized patients with CAP. Patients with a positive blood culture were categorized based on the presence or absence of a macrolide in their initial antimicrobial regimen, and severity of their CAP. Outcomes included in-hospital all-cause mortality, 30-day mortality, length of stay, and time to clinical stability. Among 549 patients with CAP and bacteremia, 247 (45%) were treated with a macrolide and 302 (55%) were not. The primary pathogen was Streptococcus pneumoniae (74%). Poisson regression with robust error variance models were used to compare the adjusted effects of each study group on the outcomes. The unadjusted 30-day mortality was 18.4% in the macrolide group, and 29.6% in the non-macrolide group (adjusted relative risk (aRR)0.81; 95% confidence interval (CI)0.50-1.33; P = 0.41). Unadjusted in-hospital all-cause mortality was 7.3% in the macrolide group, and 18.9% in the non-macrolide group (aRR 0.54, 95% CI 0.30-0.98; P = 0.043). Length of stay and time to clinical stability were not significantly different. In-hospital mortality, but not 30-day mortality, was significantly better in the macrolide group. Our data support the use of a macrolide in hospitalized patients with CAP and bacteraemia.

Predictive and prognostic factors in patients with blood-culture-positive community-acquired pneumococcal pneumonia.

In patients with pneumococcal community-acquired pneumonia (CAP), the risk factors for bacteraemia and its impact on outcomes are not fully elucidated. We aimed to compare characteristics of patients with blood-culture-positive versus blood-culture-negative pneumococcal CAP, and to characterise bacteraemic serotypes.We describe a prospective, observational study on nonimmunocompromised patients with pneumococcal CAP, from 1996 to 2013. We define severe pneumonia according to American Thoracic Society/Infectious Diseases Society of America guidelines.Of a total of 917 patients with pneumococcal CAP, 362 had blood-culture-positive pneumococcal pneumonia (BCPPP; 39%). High C-reactive protein (CRP) (≥20 mg·dL(-1)) (odds ratio (OR) 2.36, 95% CI 1.45-3.85), pleural effusion (OR 2.03, 95% CI 1.13-3.65) and multilobar involvement (OR 1.69, 95% CI 1.02-2.79) were independently associated with bacteraemic CAP, while nursing home resident (OR 0.12, 95% CI 0.01-1.00) was found as a protective factor. Despite the clinical differences, BCPPP showed similar outcomes to blood-culture-negative pneumococcal pneumonia (BCNPP). 14% of the serotypes (period 2006-2013) causing bacteraemia are included in pneumococcal conjugate vaccine PVC7, 74% in pneumococcal conjugate vaccine PVC13 and 83% in pneumococcal polysaccharide vaccine PPSV23.Pleural effusion, a high level of CRP and multilobar involvement predicted an increased risk of BCPPP. Although BCPPP patients were more severely ill at admission, mortality was not significantly greater than in BCNPP patients.

Bacteremic Pneumonia before and after Withdrawal of 13-Valent Pneumococcal Conjugate Vaccine from a Public Vaccination Program in Spain: A Case-Control Study

To compare the incidence and epidemiology of bacteremic community-acquired pneumonia (CAP) in the setting of changes in 13-valent pneumococcal conjugate vaccine (PCV13) coverage. In the region of Madrid, universal immunization with the PCV13 started in May 2010. In July 2012, public funding ceased. Vaccination coverage decreased from >95% to 82% in 2013 and to 67% in 2014. We performed a multicenter surveillance and case-control study from 2009-2014. Cases were hospitalized children with bacteremic CAP. Controls were children selected 1:1 from next-admitted with negative blood cultures and typical, presumed bacterial CAP. Annual incidence of bacteremic CAP declined from 7.9/100,000 children (95% CI 5.1-11.1) in 2009 to 2.1/100,000 children (95% CI 1.1-4.1) in 2012. In 2014, 2 years after PCV13 was withdrawn from the universal vaccination program, the incidence of bacteremic CAP increased to 5.4/100,000 children (95% CI 3.5-8.4). We enrolled 113 cases and 113 controls. Streptococcus pneumoniae caused most of bloodstream infections (78%). Empyema was associated with bacteremia (P = .003, OR 3.6; 95% CI 1.4-8.9). Simple parapneumonic effusion was not associated with bacteremia. Incomplete PCV immunization was not a risk factor for bacteremic pneumonia. High rate of PCV13 immunization was associated with decreased incidence of bacteremic CAP; this incidence increased when rate of immunization fell. Empyema (but not parapneumonic pleural effusion) was associated with bacteremia.

A review of the role of Haemophilus influenzae in community-acquired pneumonia.

In an era when Haemophilus influenzae type b (Hib) conjugate vaccine is widely used, the incidence of Hib as a cause of community-acquired pneumonia (CAP) has dramatcally declined. Non-typeable H. influenzae (NTHi) strains and, occasionally, other encapsulated serotypes of H. influenzae are now the cause of the majority of invasive H. influenzae infectons, including bacteraemic CAP. NTHi have long been recognised as an important cause of lower respiratory tract infecton, including pneumonia, in adults, especially those with underlying diseases. The role of NTHi as a cause of non-bacteraemic CAP in children is less clear. In this review the evidence for the role of NTHi and capsulated strains of H. influenzae will be examined.

De-escalation therapy among bacteraemic patients with community-acquired pneumonia

There is no evidence supporting the use of de-escalation therapy (DET) among patients with community-acquired pneumonia (CAP). We assessed the outcomes associated with DET among bacteraemic CAP patients. We performed a secondary analysis of the Community-Acquired Pneumonia Organization database, which contains data on 660 bacteraemic patients hospitalized because of CAP in 35 countries (2001–2013). Exclusion criteria were death within 72 h from admission and an inappropriate empirical antibiotic regimen. DET was defined as changing an appropriate empirical broad-spectrum regimen to a narrower-spectrum regimen according to culture results within 7 days from hospital admission. Two study groups were identified: patients whose antibiotic therapy was de-escalated (the DET group), and patients whose antibiotic therapy was not de-escalated (the N-DET group). The primary study outcome was 30-day mortality. Two hundred and sixty-one bacteraemic CAP patients were included. Gram-positive bacteria were responsible for 88.1% of the cases (Streptococcus pneumoniae, 75.9%). Gram-negative bacteria were responsible for for 7.3% of the cases. DET was performed in 165 patients (63.2%). The N-DET group was characterized by a more severe presentation at admission. After adjustment for confounders, DET was not associated with an increased risk of 30-day mortality. DET seems to be safe among bacteraemic patients with CAP. Randomized clinical trials are warranted to further explore these findings.

30-day mortality in UK patients with bacteraemic community-acquired pneumonia

To determine 7 and 30-day mortality in consecutive patients with bacteraemic community-acquired pneumonia (CAP) and the association between predicted variables and likelihood of death. From August 2007 to July 2011, demographic, clinical and microbiological data were prospectively collected on patients with bacteraemic CAP. Patients were followed until death, hospital discharge or recovery from infection. Univariate and multivariate analysis was performed to determine the association between predictor variables and 30-day mortality. 7-day mortality was 61/252 [24.4%, 95% confidence interval (CI) 19.1-30.0%] and by 30 days, this had risen to 77/252 (30.6%, 95% CI 24.9-36.6%). In univariate analysis, factors associated with 30-day mortality were age, speciality within 48 h of admission, blood culture isolate and Charlson co-morbidity index (CCI). In multivariate analysis, age and CCI remained significantly associated. There was also a trend towards significance for meticillin-sensitive Staphylococcus aureus (MSSA) and Pseudomonas aeruginosa blood culture isolates compared to Streptococcus pneumoniae. Overall, bacteraemic CAP was associated with high inpatient mortality. Because of their association with poor outcomes, patients with MSSA and P. aeruginosa bacteraemic CAP require further study.

Severe pneumococcal community-acquired pneumonia admitted to medical Tunisian ICU

Streptococcus pneumoniae is the most common cause of community-acquired pneumonia (CAP). There are no available data about this disease in Tunisian intensive care patients. The objective of this study is to describe the clinical and microbiological features of pneumococcal CAP and determine the prognostic factors. This is a retrospective cohort study of all pneumococcal CAP cases hospitalized in the medical intensive care unit (ICU) of Hospital A. Mami of Ariana (Tunisia) between January 1999 and August 2008. Included were 132 patients (mean age, 49.5 years; 82.6% males); 30 patients had received antimicrobial treatment before hospital admission. The mean of the Simplified Acute Physiology Score II was 32.9. All patients had an acute respiratory failure; 34 patients (25.8%) had pneumococcal bacteremic CAP. Among the isolated strains, 125 antimicrobial susceptibility tests were performed. The use of the new Clinical and Laboratory Standards Institute breakpoints for susceptibility when testing penicillin against S. pneumoniae showed that all isolated strains were susceptible to penicillin. The mortality rate was 25%. The need of mechanical ventilation at admission [odds ratio (OR), 3.4; 95% confidence interval (CI), 1.67–6.94; P = 0.001), Sepsis-related Organ Failure Assessment (SOFA) score at admission ≥4 (OR, 3.1; 95% CI, 1.56–6.13; P = 0.001), and serum creatinine at admission ≥102 μmol/l (OR, 1.8; 95% CI, 1.02–3.17; P = 0.043) were independent factors related to ICU mortality. In conclusion, pneumococcal CAP requiring hospitalization in the ICU is associated with high mortality. All isolated stains were susceptible to penicillin.

Absence of leukocytosis in bacteraemic pneumococcal pneumonia

Evaluation of patients with respiratory symptoms in primary care medicine is often based on peripheral WBC count that dictates the extent of diagnostic investigation. A normal WBC count may result in a limited investigation, often omitting chest radiography. To determine the extent to which patients hospitalised with bacteraemic pneumococcal pneumonia have no leukocytosis at presentation. A retrospective analysis was performed of patients with bacteraemic community-acquired pneumococcal pneumonia from 2000 to 2007 in a community care academic medical centre. Records were reviewed for symptoms, signs, and laboratory data including pneumococcal serotypes, chest radiographs on admission, and outcome. 21% of the patients presented with a normal WBC count (16.7% of the children and 25.6% of the adults). Among this population with a normal WBC count at presentation, 90% of the adults and 70% of the children developed leukocytosis within a few days after admission. In this study, in as many as one-fifth of all the patients with bacteraemic pneumococcal pneumonia, there was no leukocytosis at presentation. We therefore suggest that every patient with clinically suspected pneumonia should undergo chest radiography even if the WBC count is normal.

Community‐Acquired Bacteremic Pneumococcal Pneumonia in Children: Diagnosis and Serotyping by Real‐Time Polymerase Chain Reaction Using Blood Samples

The aim of this study was to use real-time polymerase chain reaction (RT-PCR) on blood samples to diagnose and serotype pneumococcal infection in a large cohort of Italian children hospitalized for community-acquired pneumonia. We conducted an observational study from April 2007 through June 2009 of children aged 0-16 years with a diagnosis of community-acquired pneumonia admitted to 83 pediatric hospitals in Italy. Seven hundred fifty-three children were studied. RT-PCR found pneumococcal infection in 80 (10.6%) of 753 patients. In 292 patients, culture and RT-PCR were simultaneously performed. Streptococcus pneumoniae was identified in 47 of 292 patients; 45 (15.4%) tested positive by RT-PCR and 11 (3.8%) tested positive by culture. RT-PCR was significantly more sensitive than culture in revealing bacteremic pneumonia (odds ratio, 30.6; 95% confidence interval, 5.8-97.5; P<.001). Complicated pneumonia was found in 162 (21.5%) of 753 children; 152 (93.8%) of these 162 had parapneumonic effusion, and 51 (33.6%) had empyema. Children with complicated pneumonia were significantly older. Pneumococcal bacteremia was found by RT-PCR to occur significantly more frequently in children with complications (38 [23.5%] of 162) than in children with uncomplicated pneumonia (44 [7.4%] of 591; odds ratio, 3.8; 95% confidence interval, 2.30-6.30; P<.001). RT-PCR allowed serotyping from blood in 92.5% of patients. More than two-thirds of the pneumonia cases were due to nonpneumococcal conjugate vaccine 7 serotypes. Serotype 1 was the most frequent serotype (26 [32.5%] of 80) and was significantly associated with complications (50.0% in patients with complicated pneumonia vs 18.2% in patients with uncomplicated pneumonia; odds ratio, 4.5, 95% confidence interval, 1.48-14.03; P=.005) and older age. Serotype 19A was second in frequency (15.0%) and was significantly associated with younger age. RT-PCR allows diagnosis and serotyping of pneumococcal bacteremic community-acquired pneumonia in children and is an important tool for evaluating serotype distribution in culture-negative samples.

Bacteremic community-acquired pneumonia due to Klebsiella pneumoniae: Clinical and microbiological characteristics in Taiwan, 2001-2008

BackgroundKlebsiella pneumoniae is the major cause of community-acquired pyogenic infections in Taiwan. This retrospective study evaluated the clinical and microbiological characteristics of bacteremic community-acquired pneumonia due to K. pneumoniae in Taiwanese adults.MethodsThe clinical characteristics of bacteremic community-acquired pneumonia (CAP) in adults due to K. pneumoniae were compared to those of adults with bacteremic CAP due to Streptococcus pneumoniae at a tertiary medical center in Taiwan from 2001-2008. Risk factors for mortality of bacteremic CAP due to K. pneumoniae were analyzed. All clinical isolates of K. pneumoniae were examined for capsular serotypes, hypermucoviscosity phenotype, aerobactin and rmpA gene.ResultsK. pneumoniae was the dominant cause of bacteremic CAP and was associated with a more fulminant course and a worse prognosis than bacteremic CAP due to Streptococcus pneumoniae. Initial presentation with septic shock and respiratory failure were independent risk factors for both early and total mortality. Serotype K1 and K2 comprised around half of all isolates. There were no significant differences in the clinical characteristics of patients with bacteremic CAP due to K1/K2 and non-K1/K2 isolates. Hypermucoviscosity phenotype as well as the aerobactin and rmpA genes were highly prevalent in the K. pneumoniae isolates.ConclusionsK. pneumoniae continued to be the dominant cause of bacteremic CAP in Taiwanese adults during 2001-2008. Initial presentation with septic shock and respiratory failure were independent risk factors for both early and total mortality from K. pneumoniae bacteremic CAP. Serotypes K1/K2 comprised around half of all isolates, but did not predispose patients to a poor clinical outcome. Physicians should be aware of the poor prognosis of any patient with bacteremic K. pneumoniae CAP and monitor these patients more closely.

Bacteraemic community-acquired pneumonia due to Gram-negative bacteria: incidence, clinical presentation and factors associated with severity during hospital stay

Many studies have evaluated the clinical characteristics of Gram-negative bacteria (GNB) pneumonia. However, in most cases the bacteriological diagnosis is based on unreliable respiratory samples, and research rarely focuses on only bacteraemic patients. The aim of this study was to describe the incidence, clinical characteristics, outcomes, and factors associated with severity during the hospital stay of patients diagnosed with bacteraemic community-acquired pneumonia (CAP) due to GNB. Patients consecutively admitted with bacteraemic CAP due to GNB were enrolled in the study, with exclusion of additional foci of infection. CAP due to GNB accounted for 1.2% of the total CAP cases admitted and 3.5% of those with a confirmed aetiological diagnosis. Fifty-one patients were studied (mean age: 73 ± 11.3 years). Escherichia coli (30 cases; 58.8%) and Klebsiella pneumoniae (9 cases; 17.6%) were the most commonly isolated strains. The main symptoms were fever, cough, and dyspnoea. Eleven (21.6%) patients presented mental confusion, ten (19.6%) followed a severe clinical course, and six (11.8%) died. Absence of fever, radiologically multilobar involvement, and the prescription of an inadequate empirical antimicrobial therapy were independent factors associated with severity during the hospital stay. Bacteraemic CAP due to GNB is an uncommon entity. Among the patients studied, E. coli was the main GNB found. A total of 19.6% of patients followed a severe clinical course. The factors identified in this study may alert physicians to a group of patients at risk of suffering complications during their hospital stay.

Socioeconomic and racial/ethnic disparities in the incidence of bacteremic pneumonia among US adults.

We examined associations between the socioeconomic characteristics of census tracts and racial/ethnic disparities in the incidence of bacteremic community-acquired pneumonia among US adults. We analyzed data on 4870 adults aged 18 years or older with community-acquired bacteremic pneumonia identified through active, population-based surveillance in 9 states and geocoded to census tract of residence. We used data from the 2000 US Census to calculate incidence by age, race/ethnicity, and census tract characteristics and Poisson regression to estimate rate ratios (RRs) and 95% confidence intervals (CIs). During 2003 to 2004, the average annual incidence of bacteremic pneumonia was 24.2 episodes per 100 000 Black adults versus 10.1 per 100 000 White adults (RR = 2.40; 95% CI = 2.24, 2.57). Incidence among Black residents of census tracts with 20% or more of persons in poverty (most impoverished) was 4.4 times the incidence among White residents of census tracts with less than 5% of persons in poverty (least impoverished). Racial disparities in incidence were reduced but remained significant in models that controlled for age, census tract poverty level, and state. Adults living in impoverished census tracts are at increased risk of bacteremic pneumonia and should be targeted for prevention efforts.

Update in Pulmonary and Critical Care Medicine

This Update in Pulmonary and Critical Care Medicine features 12 articles published in 2009. Topics include chronic obstructive pulmonary disease, asthma, pneumonia, glucose control and mortality, e...