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Pulmonary complications of pneumococcal community-acquired pneumonia: incidence, predictors, and outcomes

  • C. Cillóniz
    Affiliations
    Department of Pneumology, Institut Clinic del Tórax, Hospital Clinic of Barcelona, Barcelona, Spain

    Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), University of Barcelona (UB), Barcelona, Spain

    SGR 911, Ciber de Enfermedades Respiratorias (CIBERES), Barcelona, Spain
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  • S. Ewig
    Affiliations
    Thoraxzentrum Ruhrgebiet, Kliniken für Pneumologie und Infektiologie, EVK Herne und Augusta-Kranken-Anstalt, Bochum, Germany
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  • E. Polverino
    Affiliations
    Department of Pneumology, Institut Clinic del Tórax, Hospital Clinic of Barcelona, Barcelona, Spain

    Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), University of Barcelona (UB), Barcelona, Spain

    SGR 911, Ciber de Enfermedades Respiratorias (CIBERES), Barcelona, Spain
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  • C. Muñoz-Almagro
    Affiliations
    Department of Molecular Microbiology, University Hospital Sant Joan de Déu Esplugues, Barcelona, Spain
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  • F. Marco
    Affiliations
    Department of Microbiology, Hospital Clinic of Barcelona, Barcelona, Spain
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  • A. Gabarrús
    Affiliations
    Department of Pneumology, Institut Clinic del Tórax, Hospital Clinic of Barcelona, Barcelona, Spain

    Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), University of Barcelona (UB), Barcelona, Spain

    SGR 911, Ciber de Enfermedades Respiratorias (CIBERES), Barcelona, Spain
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  • R. Menéndez
    Affiliations
    SGR 911, Ciber de Enfermedades Respiratorias (CIBERES), Barcelona, Spain

    Department of Pneumology, University Hospital La Fe, Valencia, Barcelona, Spain
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  • J. Mensa
    Affiliations
    Department of Infectious Disease, Hospital Clinic, Barcelona, Spain
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  • A. Torres
    Correspondence
    Corresponding author: A. Torres, Department of Pneumology, Hospital Clinic of Barcelona, Villarroel 170, 08036, Barcelona, Spain
    Affiliations
    Department of Pneumology, Institut Clinic del Tórax, Hospital Clinic of Barcelona, Barcelona, Spain

    Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), University of Barcelona (UB), Barcelona, Spain

    SGR 911, Ciber de Enfermedades Respiratorias (CIBERES), Barcelona, Spain
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      Abstract

      The aim of this study was to evaluate the clinical characteristics, predictors and outcomes of pneumococcal pneumonia developing pulmonary complications and the distribution of pneumococcal serotypes. It was a prospective study including all adult patients admitted to the Hospital Clinic of Barcelona, Spain (2001–2009) with the diagnosis of pneumococcal pneumonia. Microbiological investigation was systematically performed, including antimicrobial susceptibility and serotype distribution (only invasive strains isolated during 2006–2009). Complicated pneumonia was defined as the presence of one or more pulmonary complications: pleural effusion, empyema, or multilobar infiltrates. We included 626 patients, and 235 (38%) had the following pulmonary complications: pleural effusion, 122 (52%); empyema, 18 (8%); and multilobar infiltration, 151 (64%). Forty-six (20%) patients had more than one complication. Patients with pulmonary complications showed a higher rate of intensive-care unit admission (34% vs. 13%, p <0.001), a higher rate of shock (16% vs. 7%, p <0.001), a longer length of stay (9 days vs. 6 days, p <0.001), and a lower rate of penicillin resistance (14% vs. 25%, p 0.013), but similar mortality (9% vs. 8%). No significant differences were observed in the serotype distribution between complicated and uncomplicated pneumonia. Chronic obstructive pulmonary disease (COPD) (OR 0.38, 95% CI 0.23–0.63; p <0.001) was a protective factor against pulmonary complications, whereas chronic liver disease (OR 3.60, 95% CI 1.71–7.60; p 0.001), admission C-reactive protein level ≥18 mg/dL (OR 2.77, 95% CI 1.91–4.00; p <0.001) and admission creatinine level >1.5 mg/dL (OR 2.01, 95% CI 1.31–3.08; p 0.001) were risk factors for pulmonary complications. Complicated pneumonia was characterized by a more severe clinical presentation, but was not associated with increased mortality. Resistance to antibiotics was lower in complicated cases. No significant differences were observed in the serotype distribution between complicated and uncomplicated pneumonia. In the multivariate analysis, COPD was a protective factor against pulmonary complications.

      Keywords

      Introduction

      Streptococcus pneumoniae is the most frequent aetiological agent of community-acquired pneumonia (CAP) [
      • Van Der PT.
      • Opal SM.
      Pathogenesis, treatment, and prevention of pneumococcal pneumonia.
      ]. Since the addition of a heptavalent protein–polysaccharide conjugate vaccine (PCV7) to the routine childhood vaccination schedule, numerous studies have documented declining rates of colonization with PCV7 serotypes and a lower incidence of PCV7-type invasive pneumococcal disease (IPD) among young children and adults. Despite the effectiveness of the conjugate vaccine, the emergence of IPD caused by non-vaccine serotypes has been reported [
      • Goldbart AD.
      • Leibovitz E.
      • Porat N
      • et al.
      Complicated community acquired pneumonia in children prior to the introduction of the pneumococcal conjugated vaccine.
      ,
      • Munoz-Almagro C.
      • Jordan I.
      • Gene A
      • et al.
      Emergence of invasive pneumococcal disease caused by nonvaccine serotypes in the era of 7-valent conjugate vaccine.
      ,
      • Ardanuy C.
      • Tubau F.
      • Pallares R
      • et al.
      Epidemiology of invasive pneumococcal disease among adult patients in Barcelona before and after pediatric 7-valent pneumococcal conjugate vaccine introduction, 1997–2007.
      ].
      Most cases of adult pneumococcal pneumonia are self-limiting, and patients fully recover. A subset of patients have a more complicated course associated with pulmonary complications, including pleural effusion, empyema, and multilobar consolidation or cavitations.
      Among potential complications, pleural effusion is very frequent, as up to 57% of hospitalized pneumonia patients may develop it [
      • Light RW.
      • Girard WM.
      • Jenkinson SG
      • et al.
      Parapneumonic effusions.
      ,
      • Taryle DA.
      • Potts DE.
      • Sahn SA.
      The incidence and clinical correlates of parapneumonic effusions in pneumococcal pneumonia.
      ]. Moreover, it is considered to be an indicator of severity of pneumonia, and is clearly associated with an increased risk of treatment failure [
      • Mandell LA.
      • Wunderink RG.
      • Anzueto A
      • et al.
      Infectious Diseases Society of America/American Thoracic Society consensus guidelines on the management of community-acquired pneumonia in adults.
      ,
      • Menendez R.
      • Torres A.
      • Zalacain R
      • et al.
      Risk factors of treatment failure in community acquired pneumonia: implications for disease outcome.
      ,
      • Lim WS.
      • Baudouin SV.
      • George RC
      • et al.
      BTS guidelines for the management of community acquired pneumonia in adults: update 2009.
      ].
      The occurrence of empyema is one of the main factors associated with poor outcome in CAP [
      • Roson B.
      • Carratala J.
      • Fernandez-Sabe N
      • et al.
      Causes and factors associated with early failure in hospitalized patients with community-acquired pneumonia.
      ], and is a frequent cause of prolonged treatment (medical and surgical) and hospital stay [
      • Chalmers JD.
      • Singanayagam A.
      • Murray MP
      • et al.
      Risk factors for complicated parapneumonic effusion and empyema on presentation to hospital with community-acquired pneumonia.
      ], and even of treatment failure [
      • Mandell LA.
      • Wunderink RG.
      • Anzueto A
      • et al.
      Infectious Diseases Society of America/American Thoracic Society consensus guidelines on the management of community-acquired pneumonia in adults.
      ,
      • Menendez R.
      • Torres A.
      • Zalacain R
      • et al.
      Risk factors of treatment failure in community acquired pneumonia: implications for disease outcome.
      ].
      Multilobar consolidation is one of the minor criteria for defining severe CAP and evaluating the need for intensive-care unit (ICU) admission, and is associated with treatment failure [
      • Mandell LA.
      • Wunderink RG.
      • Anzueto A
      • et al.
      Infectious Diseases Society of America/American Thoracic Society consensus guidelines on the management of community-acquired pneumonia in adults.
      ,
      • Menendez R.
      • Torres A.
      • Zalacain R
      • et al.
      Risk factors of treatment failure in community acquired pneumonia: implications for disease outcome.
      ,
      • Roson B.
      • Carratala J.
      • Fernandez-Sabe N
      • et al.
      Causes and factors associated with early failure in hospitalized patients with community-acquired pneumonia.
      ]. Moreover, different authors have found that multilobar infiltration is an independent risk factor for increased mortality in CAP [
      • Lim WS.
      • Baudouin SV.
      • George RC
      • et al.
      BTS guidelines for the management of community acquired pneumonia in adults: update 2009.
      ,
      • Garcia-Vidal C.
      • Fernandez-Sabe N.
      • Carratala J
      • et al.
      Early mortality in patients with community-acquired pneumonia: causes and risk factors.
      ]. Adults with these complications often require prolonged hospitalization, and are at risk of significant and long-lasting morbidity [
      • Light RW.
      • Girard WM.
      • Jenkinson SG
      • et al.
      Parapneumonic effusions.
      ,
      • Lim WS.
      • Baudouin SV.
      • George RC
      • et al.
      BTS guidelines for the management of community acquired pneumonia in adults: update 2009.
      ].
      Although the overall burden of IPD has decreased, the incidence of complicated pneumonia may be rising. Several studies have shown an increase in the frequency of pulmonary complications among children [
      • Obando I.
      • Munoz-Almagro C.
      • Arroyo LA
      • et al.
      Pediatric parapneumonic empyema, Spain.
      ,
      • Tan TQ.
      • Mason Jr, EO
      • Barson WJ
      • et al.
      Clinical characteristics and outcome of children with pneumonia attributable to penicillin-susceptible and penicillin-nonsusceptible Streptococcus pneumoniae.
      ,
      • Byington CL.
      • Hulten KG.
      • Ampofo K
      • et al.
      Molecular epidemiology of pediatric pneumococcal empyema from 2001 to 2007 in Utah.
      ]. This increase does not appear to be related to the concurrent increase in the frequency of penicillin-resistant S. pneumoniae, but does appear to be related to the introduction of virulent clones expressing non-vaccine serotypes, especially serotype 1. Serotype distributions may be relevant in this trend. Likewise, host factors such as age, gender and the presence of comorbidities have been related to invasive pneumococcal pneumonia and may be risk factors for the development of complicated pneumonia. On the other hand, data on the clinical manifestations in an adult population with complicated pneumococcal pneumonia are limited. This study was undertaken to evaluate the clinical characteristics and outcomes of adults with pneumococcal pneumonia, especially those with pulmonary complications.

      Materials and Methods

       Study population

      The study population consisted of adults consecutively admitted to the Hospital Clinic of Barcelona (Spain), an 800-bed third-level hospital covering an urban population of 540 000 inhabitants, between 2001 and 2009, with a diagnosis of pneumococcal pneumonia.
      At the initial visit, patients underwent a complete clinical history and physical examination. Patients were stratified into risk classes with the validated prediction rule calculated according to Pneumonia Severity Index (PSI) scores. Empirical antibiotic treatment was administered according to hospital guidelines. All surviving patients were visited at 30–40 days after discharge.

       Microbiological evaluation and diagnostic criteria

      Regular sampling included sputum specimens, two blood cultures and urine samples for detection of S. pneumoniae (Binax Now S. pneumoniae Urinary Antigen Test; Emergo Europe, The Hague, The Netherlands) and Legionella pneumophila serogroup 1 (Binax Now L. pneumophila Urinary Antigen Test; Trinity Biotech, Bray, Ireland). Samples from pleural fluid puncture, tracheobronchial aspiration and blind bronchoalveolar lavage were obtained according to the judgement of the attending physician.
      The diagnosis of pneumonia was established in the presence of clinical symptoms and a new infiltrate on the chest radiograph and no alternative diagnosis during follow-up. The aetiology of pneumococcal pneumonia was determined in cases with a positive valid sputum culture, positive blood culture, positive pleural fluid and transthoracic needle aspiration cultures, positive urinary antigen for S. pneumoniae, bacterial growth in cultures of tracheobronchial aspiration specimens of ≥105 CFU/mL, bacterial growth in cultures of phosphate-buffered saline of ≥10 CFU/mL, and bacterial growth in cultures of bronchoalveolar lavage specimens of ≥104 CFU/mL.
      Pneumococcal isolates were identified with standard microbiological methods. All strains isolated from normally sterile sites were routinely frozen at -70°C in skimmed milk. Later, molecular serotype detection was performed with a published Multiplex real-time assay [
      • Lim WS.
      • Baudouin SV.
      • George RC
      • et al.
      BTS guidelines for the management of community acquired pneumonia in adults: update 2009.
      ] at the Molecular Microbiology Department, Hospital Sant Joan de Deu, Barcelona. This PCR procedure allows differentiation of 24 serotypes (1, 3, 5, 4, 6A, 6B, 7F/A, 8, 9V/A/N/L, 14, 15B/C, 18C/B, 19A, 19F/B/C, 23F and 23A). Strains not typeable by real-time PCR were consecutively serotyped with the Quellung reaction, using rabbit polyclonal antisera from the Statens Serum Institute (Copenhagen, Denmark) at the National Pneumococcus Reference Centre (Majadahonda, Madrid). Serotyping was performed only in invasive strains isolated during the period from 2006 to 2009.
      Strains were initially screened for susceptibility to antimicrobial agents with Sensititre (Trek Diagnostic Systems, East Grinstead, UK). Penicillin susceptibility and other antibiotic susceptibilities were defined according to the 2008 breakpoints of the CLSI [
      National Committee for Clinical Laboratory Standards
      ].

       Definitions of pulmonary complications

      Complicated pneumonia was defined as the presence of one or more of the following pulmonary complications: pleural effusion, empyema, or multilobar infiltrates. We included only meaningful pleural effusions in which thoracocentesis was performed and pleural fluid was obtained. Pleural empyema was diagnosed if (i) the Gram stain was positive or a pathogen was cultured from pleural fluid, or (ii) at least two of the following criteria were fulfilled by pleural fluid analysis: glucose ≤40 mg/dL, lactate dehydrogenase ≥1000 u/L, pH ≤7.2, and white blood cell count of 10 000 cells/mL. Multilobar pneumonia was defined as a chest X-ray infiltrate involving two or more lobes [
      • Goldbart AD.
      • Leibovitz E.
      • Porat N
      • et al.
      Complicated community acquired pneumonia in children prior to the introduction of the pneumococcal conjugated vaccine.
      ].
      Exclusion criteria were as follows: (i) severe immunosuppression, such as solid organ or bone marrow transplantation or AIDS, receiving chemotherapy or other immunosuppressive drugs (>20 mg of prednisone equivalent per day for 2 weeks or more), or asplenia; (ii) hospitalization in the preceding 21 days; (iii) active tuberculosis; and (iv) healthcare-associated pneumonia according to American Thoracic Society/Infectious Diseases Society of America guidelines [
      • Mandell LA.
      • Wunderink RG.
      • Anzueto A
      • et al.
      Infectious Diseases Society of America/American Thoracic Society consensus guidelines on the management of community-acquired pneumonia in adults.
      ]. Patients were categorized into two groups on the basis of the presence or absence of pulmonary complications: uncomplicated and complicated pneumonia.

       Statistical analysis

      Categorical variables were described by frequencies and percentages, and continuous variables by means and standard deviations, or the median and interquartile range for data that were not normally distributed (Kolmogorov–Smirnov test). Categorical variables were compared by use of the chi-square test or Fisher's exact test where appropriate. Continuous variables were compared by use of Student's t-test once normality was demonstrated; otherwise, the non-parametric Mann–Whitney U-test was performed.
      Univariate and multivariate logistic regression analyses were performed to identify variables predictive of patients with pulmonary complications (dependent variable). The variables analysed univariately were: age, gender, smoking, alcohol consumption, previous antibiotic use, influenza vaccine, pneumococcal vaccine, systemic corticosteroids, chronic obstructive pulmonary disease (COPD), chronic cardiovascular disease, diabetes mellitus, neurological disease, chronic renal failure, chronic liver disease, bacteraemia, creatinine, C-reactive protein (CRP) level, and white blood cell count. Interactions between variables were specifically searched for. Variables that showed a significant result univariately (p <0.1) were included in the multivariate logistic regression backward stepwise model. Variables that were highly correlated were excluded from multivariate analyses. The Hosmer-Lemeshow goodness-of-fit test was performed to assess the overall fit of the model [
      • Hosmer D.
      • Lemeshow S.
      ]. All tests were two-tailed, and significance was set at 5%. All analyses were performed with SPSS version 16.0 for Windows (SPSS, Chicago, IL, USA).

      Results

       General characteristics of the study population

      A total of 626 patients were included during the study period from 2001 to 2009. The mean age was 63.6 ± 18.9 years (289 patients (46%) were aged ≤65 years), and 355 (57%) of the patients were male.
      On admission, the patients were classified by PSI score as being in the low-risk group (I–III) (n = 299, 48%), the intermediate-risk group (IV) (n = 214, 34%), and the high-risk group (V) (n = 113, 18%). Fifty-four patients (9%) died within 30 days of admission. Table 1 summarizes the main characteristics of the 626 patients.
      TABLE 1Demographic and clinical characteristics of patients with pneumococcal pneumonia
      General characteristicsPneumococcal pneumonia (N = 626)
      Demographics
      Age (years), mean (SD)63.6 (18.9)
      Sex (male), n (%)355 (57)
      Current smoking, n (%)198 (31.9)
      Current alcohol abuse, n (%)104 (16.8)
      Previous antibiotic, n (%)85 (16.0)
      Influenza vaccine, n (%)213 (39.1)
      Pneumococcal vaccine, n (%)79 (14.6)
      Inhaled corticosteroid, n (%)
      Treatment before admission for pneumonia episode.
      133 (21.3)
      Systemic corticosteroid, n (%)
      Treatment before admission for pneumonia episode.
      13 (2.2)
      Comorbidity, n (%)
      Chronic respiratory disease275 (44.2)
      Bronchiectasis64 (10.3)
      COPD130 (21.0)
      Asthma41 (6.6)
      Other40 (6.4)
      Chronic cardiovascular disease, n (%)84 (13.5)
      Diabetes mellitus, n (%)105 (16.9)
      Neurological disease, n (%)87 (14.0)
      Chronic renal failure, n (%)31 (5.0)
      Chronic liver disease, n (%)38 (6.1)
      Pulmonary complications, n (%)
      Forty-six patients had more than one pulmonary complication.
      Multilobar infiltration151 (64.2)
      Pleural effusion122 (51.9)
      Empyema18 (7.6)
      PSI I–III, n (%)299 (47.8)
      PSI IV–V, n (%)327 (52.2)
      Bacteraemia, n (%)206 (32.9)
      ICU admission, n (%)132 (21.1)
      Mechanical ventilation, n (%)55 (9.8)
      Length of hospital stay (days), median (IQR)9.4 ± 6
      30-day mortality, n (%)54 (8.7)
      COPD, chronic obstructive pulmonary disease; ICU, intensive-care unit; IQR, interquartile range; PSI, Pneumonia Severity Index; SD, standard deviation.
      a Treatment before admission for pneumonia episode.
      b Forty-six patients had more than one pulmonary complication.

       Pulmonary complications

      Of the 626 patients, 235 (38%) had pulmonary complications, distributed as follows: pleural effusion, 122 (52%); empyema, 18 (8%); and multilobar infiltration, 151 (62%). Forty-six (20%) had more than one of the pulmonary complications. The characteristics of the patients with complicated and uncomplicated pneumonia are summarized in TABLE 2, TABLE 3, TABLE 4, TABLE 5.
      TABLE 2Characteristics of patients with complicated community-acquired pneumonia (CAP) and uncomplicated CAP
      VariableComplicated CAP (N = 235)
      Complicated CAP caused by multilobar involvement (two or more lobes) in 151 cases (64%), pleural effusion in 122 cases (52%), and empyema in 18 cases (8%). Forty-six (20%) patients had more than one complication.
      Uncomplicated CAP (N = 391)
      Complicated CAP caused by multilobar involvement (two or more lobes) in 151 cases (64%), pleural effusion in 122 cases (52%), and empyema in 18 cases (8%). Forty-six (20%) patients had more than one complication.
      p-Value
      Demographics
      Age (years), mean (SD)61.6 (18.5)64.9 (19.0)0.027
      Age >65 years, n (%)111 (47.2)226 (57.8)0.010
      Sex (male), n (%)129 (54.9)226 (57.8)0.48
      Current smoking, n (%)83 (35.8)115 (29.6)0.11
      Current alcohol abuse, n (%)47 (20.2)57 (14.8)0.07
      Previous antibiotic, n (%)34 (17.4)51 (15.0)0.47
      Influenza vaccine, n (%)64 (31.4)149 (43.7)0.004
      Pneumococcal vaccine, n (%)23 (11.3)56 (16.5)0.10
      Inhaled corticosteroid, n (%)
      Treatment before admission for pneumonia episode.
      29 (12.4)104 (26.7)<0.001
      Systemic corticosteroid, n (%)
      Treatment before admission for pneumonia episode.
      3 (1.4)10 (2.7)0.30
      Comorbidity, n (%)
      Chronic respiratory disease<0.001
      Bronchiectasis26 (11.2)38 (9.8)0.58
      COPD28 (12.0)102 (26.2)<0.001
      Asthma19 (8.2)22 (5.7)0.22
      Other28 (7.2)12 (5.2)0.31
      Chronic cardiovascular disease, n (%)25 (10.7)59 (15.1)0.12
      Diabetes mellitus, n (%)34 (14.7)71 (18.3)0.25
      Neurological disease, n (%)33 (14.1)54 (14.0)0.97
      Chronic renal failure, n (%)9 (3.9)22 (5.7)0.32
      Chronic liver disease, n (%)22 (9.4)16 (4.1)0.008
      Clinical manifestations, n (%)
      Fever215 (91.9)336 (85.9)0.026
      Dyspnoea191 (81.3)267 (68.3)<0.001
      Chest pain146 (62.1)215 (55.1)0.09
      Acute renal failure54 (23.4)41 (10.6)<0.001
      Shock37 (15.9)28 (7.2)<0.001
      Clinical findings
      Temperature (°C), median (IQR)37.6 (1.6)38.0 (1.5)0.013
      Systolic blood pressure (mmHg), median (IQR)120.0 (39.0)124.5 (34.5)0.08
      Laboratory findings
      Creatinine (mg/dL), median (IQR)1.1 (0.8)1.1 (0.5)0.11
      Creatinine >1.5 mg/dL, n (%)62 (26.4)62 (15.9)0.001
      C-reactive protein level (mg/dL), median (IQR)25.1 (18.3)17.4 (19.4)<0.001
      C-reactive protein level ≥18 mg/dL, n (%)166 (71.6)182 (48.0)<0.001
      WBC count (109 cell/L), median (IQR)14.9 (10.3)15.9 (9.0)0.028
      Saturated O2 (%), median (IQR)92.0 (6.9)93.9 (5.5)<0.001
      Saturated O2 <92%, n (%)81 (46.8)84 (32.7)0.003
      PaO2/FiO2 ratio, median (IQR)266.7 (71.4)287.1 (89.9)<0.001
      PaO2/FiO2 ratio <200, n (%)28 (14.5)17 (5.4)<0.001
      PSI IV–V, n (%)134 (57.0)193 (49.4)0.06
      Bacteraemia, n (%)93 (39.6)113 (28.9)0.006
      ICU admission, n (%)80 (34.0)52 (13.3)<0.001
      Mechanical ventilation, n (%)32 (15.5)23 (6.5)<0.001
      Length of hospital stay (days), median (IQR)9.0 (9.0)6.0 (6.0)<0.001
      30-day mortality, n (%)22 (9.4)32 (8.2)0.62
      COPD, chronic obstructive pumonary disease; ICU, intensive-care unit; IQR, interquartile range; PSI, Pneumonia Severity Index; SD, standard deviation; WBC, white blood cell.
      a Complicated CAP caused by multilobar involvement (two or more lobes) in 151 cases (64%), pleural effusion in 122 cases (52%), and empyema in 18 cases (8%). Forty-six (20%) patients had more than one complication.
      b Treatment before admission for pneumonia episode.
      TABLE 3Patients with multilobar involvement
      VariableMultilobar involvement (N = 155)
      PSI IV–V, n (%)89 (58.9)
      Bacteraemia, n (%)65 (43.0)
      ICU admission, n (%)57 (37.7)
      Mechanical ventilation, n (%)28 (21.5)
      Length of hospital stay (days), median (IQR)9.0 (9.0)
      30-day mortality, n (%)18 (11.9)
      ICU, intensive-care unit; IQR, interquartile range; PSI, Pneumonia Severity Index.
      TABLE 4Patients with pleural effusion
      VariablePleural effusion (N = 122)
      PSI IV–V, n (%)72 (59.0)
      Bacteraemia, n (%)40 (32.8)
      ICU admission, n (%)44 (36.1)
      Mechanical ventilation, n (%)13 (12.0)
      Length of hospital stay (days), median (IQR)10.0 (9.0)
      30-day mortality, n (%)10 (8.2)
      ICU, intensive-care unit; IQR, interquartile range; PSI, Pneumonia Severity Index.
      TABLE 5Patients with empyema
      VariableEmpyema (N = 18)
      PSI IV–V, n (%)10 (55.6)
      Bacteraemia, n (%)4 (22.2)
      ICU admission, n (%)7 (38.9)
      Mechanical ventilation, n (%)2 (14.3)
      Length of hospital stay (days), median (IQR)13.5 (9.0)
      30-day mortality, n (%)2 (11.1)
      ICU, intensive-care unit; IQR, interquartile range; PSI, Pneumonia Severity Index.
      The main parameters of clinical severity (PSI, ICU, mechanical ventilation (MV), etc.) showed a homogeneous distribution among patients with different pulmonary complications, with the exception of bacteraemia, which showed a tendency to be more frequent among patients with multilobar involvement (TABLE 2, TABLE 3, TABLE 4, TABLE 5). A higher proportion of patients aged >65 years was observed in the complicated pneumonia group (47% vs. 58%, p 0.010). There were no differences in smoking or alcohol consumption between the two groups. There was a difference in temperature at admission (p 0.013). CRP level ≥18 mg/dL (p <0.001) and creatinine level >1.5 mg/dL (p 0.001) were higher in patients with complicated pneumonia. However, patients with complicated pneumonia had fewer comorbidities (<1 comorbidity) than patients with uncomplicated pneumonia (57% vs. 69%, p 0.003), and a lower rate of influenza vaccination (p 0.004).
      Complicated pneumonia patients had a longer length of hospital stay (p <0.001), more frequent admission to the ICU (p <0.001), more frequent shock (p <0.001) and longer time to clinical stability (8 days vs. 5 days, p <0.001) than uncomplicated pneumonia patients. The mortality rate was similar in both groups (9% vs. 8%), despite the higher frequency of bacteraemia and shock observed in complicated cases (p 0.005 and p 0.001, respectively). The analysis of mortality did not show significant differences between groups when sthe different pulmonary complications were split (multilobar, 18 (12%); pleural effusion, 10 (8%); and empyema, 2 (11%)) (TABLE 2, TABLE 3, TABLE 4, TABLE 5).

       Diagnosis of pneumococcal pneumonia resistance to antibiotics and serotypes

      The S. pneumoniae antigen was detected in 404 patients from urine (65%), and was isolated by culture in 221 (35%) sterile samples (203 from blood and 18 from pleural fluid). In addition, S. pneumoniae was isolated in 13 (2%) patients from bronchial aspirate sample and in 128 (20%) from sputum samples.
      MIC testing was performed for 333 of 362 (92%) S. pneumoniae isolates. A total of 69 pneumococcal isolates showed some degree of penicillin non-sensitivity; resistance was intermediate (MIC 4 mg/L) in 38 and high (MIC ≥8 mg/L) in 31. In addition, 56 pneumococcal isolates were non-susceptible to erythromycin (resistance was intermediate (MIC 0.5 mg/L) in two and high (MIC ≥1 mg/L) in 54). The rates of penicillin and erythromycin resistance were almost two-fold higher in uncomplicated pneumonia cases (p 0.036 and, p 0.027, respectively) (Table 6).
      TABLE 6Results of penicillin and erythromycin resistance testing of Streptococcus pneumoniae isolates from patients with complicated or uncomplicated pneumococcal pneumonia
      Complicated (N = 135)Uncomplicated (N = 198)
      Penicillin resistance (MIC; mg/mL)
      For penicillin resistance, data were available for 333 patients.
      No. of isolates (%)No. of isolates (%)p-Value 0.036
      Susceptible, MIC ≤2116 (85.9)148 (74.7)0.013
      Intermediately susceptible, MIC 49 (6.7)29 (14.6)0.024
      Resistant, MIC ≥810 (7.4)21 (10.6)0.32
      Complicated (N = 134)Uncomplicated (N = 194)p-Value 0.027
      Erythromycin resistance (MIC; mg/mL)
      For erythromycin resistance, data were available for 328 patients.
      No. of isolates (%)No. of isolates (%)
      Susceptible, MIC ≤0.25117 (87.3)155 (79.9)0.08
      Intermediately susceptible, MIC 0.52 (1.5)0 (0)0.17
      Resistant, MIC ≥115 (11.2)39 (20.1)0.033
      a For penicillin resistance, data were available for 333 patients.
      b For erythromycin resistance, data were available for 328 patients.
      Eighty-four of 221 (38%) invasive isolates were available for serotyping (2006–2009 period). The most frequent serotypes in this population were 1 (n = 27, 32%), 19A (n = 15, 18%), 3 (n = 7, 8%), 14 (n = 5, 6%), 7F (n = 5, 6%), and 5 (n = 4, 5%), as summarized in Table 7. No significant differences were observed in the serotype distribution of complicated and uncomplicated pneumonia. However, a non-significant trend for a higher frequency of serotype 19A was observed in complicated pneumonia patients. Serotypes covered by the PCV7 vaccine (4, 6B, 9V, 14, 18C, 19F, and 23F) represented only 13% of all serotypes; 87% were not included in the vaccine. There were no statistically significant differences (p 0.42) when different serotypes and pulmonary complications were compared (PCV7 serotype vs. non-PCV7 serotypes).
      TABLE 7Serotype distribution of 84 Streptococcus pneumoniae isolates (years 2006–2009)
      Pneumococcal “serotypeComplicated CAP (N = 52), n (%)Uncomplicated (N = 32), n (%)
      117 (32.6)10 (31.2)
      35 (9.6)2 (6.2)
      42 (3.8)1 (3.1)
      53 (5.7)1 (3.1)
      6A1 (1.9)0 (0)
      7F1 (1.9)4 (12.5)
      80 (0)1 (3.1)
      9N0 (0)1 (3.1)
      9A1 (1.9)0 (0)
      9V2 (3.8)0 (0)
      10A1 (1.9)0 (0)
      11F0 (0)1 (0)
      12F3 (5.7)0 (0)
      144 (7.6)1 (3.1)
      19A11 (21.1)4 (12.5)
      19F0 (0)1 (3.1)
      22F0 (0)1 (3.1)
      24F0 (0)3 (9.3)
      290 (0)1 (3.1)
      311 (1.9)0 (0)
      CAP, community-acquired pneumonia.

       Predictors of complicated pneumonia

      Univariate analysis revealed the following protective factors against complicated pneumonia: age >65 years, presence of COPD, absence of chronic liver disease, absence of bacteraemia, low CRP levels (<18 mg/dL), and low creatinine levels (≤1.5 mg/dL) (Table 8).
      TABLE 8Significant univariate and multivariate logistic regression analyses of complicated pulmonary pneumonia
      UnivariateMultivariate
      Hosmer–Lemeshow goodness-of-fit test: p 0.57.
      VariableOR95% CIp-ValueOR95% CIp-Value
      Age >65 years0.650.47–0.900.010
      Pneumococcal vaccine0.650.38–1.090.099
      Chronic respiratory disease
      The p-value corresponds to differences between the five groups (none, bronchiectasis, COPD, asthma, or other chronic respiratory disease). The OR and 95% CI of bronchiectasis, COPD, asthma and other chronic respiratory disease are related to cases with no chronic respiratory disease.
      0.0010.001
      None11
      Bronchiectasis0.920.53–1.580.760.840.47–1.490.55
      COPD0.370.23–0.59<0.0010.380.23–0.63<0.001
      Asthma1.160.61–2.220.651.430.72–2.860.31
      Other0.580.28–1.170.130.510.24–1.100.084
      Chronic liver disease2.421.24–1.710.0093.601.71–7.600.001
      Bacteraemia1.611.15–2.270.006
      Creatinine >1.5 mg/dL1.901.27–2.820.0022.011.31–3.080.001
      C-reactive protein ≥18 mg/dL2.721.92–3.86<0.0012.771.91–4.00<0.001
      COPD, chronic obstructive pulmonary disease.
      a Hosmer–Lemeshow goodness-of-fit test: p 0.57.
      b The p-value corresponds to differences between the five groups (none, bronchiectasis, COPD, asthma, or other chronic respiratory disease). The OR and 95% CI of bronchiectasis, COPD, asthma and other chronic respiratory disease are related to cases with no chronic respiratory disease.
      In multivariate analysis, a protective association of complicated pneumonia was evident in patients with COPD (OR 0.38, 95% Cl 0.23–0.63; p <0.001). Chronic liver disease (OR 3.60, 95% Cl 1.71–7.60; p 0.001), CRP level ≥18 mg/dL (OR 2.77, 95% CI 1.91–4.00; p <0.001) and creatinine level >1.5 mg/dL (OR 2.01, 95% CI 1.31–3.08; p 0.001) were risk factors for pulmonary complications (Table 8).

       Antibiotic treatment

      Data on antibiotic treatment was available for 620 (99%) patients, as follows: β-lactam plus macrolide (241, 39%); β-lactam plus fluoroquinolone (168, 27%); fluoroquinolone alone (136, 22%); β-lactam alone (52, 8%); macrolide plus fluoroquinolone (six, 1%); macrolide alone (two, 0.3%); and other combinations (15, 2%) (Table 9).
      TABLE 9Initial antibiotic treatment by study group
      Antibiotic treatmentComplicated CAP (N = 235), n (%)Uncomplicated CAP (N = 391), n (%)p-Value
      β-Lactam + macrolide90 (38.3)151 (38.6)0.94
      β-Lactam + fluoroquinolone85 (36.2)83 (21.2)<0.001
      Macrolide + fluoroquinolone1 (0.4)5 (1.3)0.42
      Other combinations4 (1.7)11 (2.8)0.38
      Fluoroquinolone monotherapy32 (13.6)104 (26.6)<0.001
      β-Lactam monotherapy22 (9.4)30 (7.7)0.46
      Macrolide monotherapy0 (0)2 (0.5)0.53
      Unknown therapy1 (0.4)5 (1.3)0.42
      β-Lactams include: ceftriaxone (1 or 2 g per day for 7 days); amoxycillin–clavulanic (1 g every 8 h for 7 days); cefotaxime (1 or 2 g every 8 h for 7 days). Fluoroquinolones include: levofloxacin (500 mg every 12 h or 500 mg every 24 h for 7–10 days); moxifloxacin (400 mg every 24 h for 5–7 days). Macrolides include: azithromycin (500 mg per day for 3–6 days). Other combinations include: ceftriaxone (1 g every 24 h) plus clindamicin (600 mg every 8 h); amikacin (15 mg/kg every 24 h) plus levofloxacin (500 mg every 24 h); and meropenem (1 g every 6–8 h) plus levofloxacin (500 mg every 24 h).
      A β-lactam plus a fluoroquinolone was more frequently (p <0.001) administered to patients with pulmonary complications. However, a fluroquinolone as monotherapy was less frequently administered (p <0.001) (Table 9). We did not find initially inadequate antibiotic treatments in the population for which an antibiogram was available.

      Discussion

      The most important findings of our study are as follows: (i) pulmonary complications were frequent (38%) in patients with pneumococcal CAP; (ii) although mortality was similar between the groups, patients with pulmonary complications presented a higher rate of bacteraemia, shock, and need for MV, with a subsequent increase in the rate of ICU admission and length of stay; (iii) patients with pulmonary complications had a lower rate of penicillin and macrolide resistance; (iv) pulmonary complications were not significantly different when PCV7 serotypes were compared with non-PCV7 serotypes; (v) and COPD was a protective factor against pulmonary complications.
      In the present study, we found that patients with pneumococcal pneumonia had 38% of pulmonary complications as defined. This is the first study evaluating the clinical impact of pulmonary complications in hospitalized adults with pneumococcal pneumonia. Other publications have reported these complications only erratically. For example, in a previous study in adults, empyema was reported in 2% [
      • Ahmed RA.
      • Marrie TJ.
      • Huang JQ.
      Thoracic empyema in patients with community-acquired pneumonia.
      ], and another study reported multilobar infiltrates in 37% [
      • Saldias PF.
      • Viviani GP.
      • Pulgar BD
      • et al.
      Prognostic factors and mortality in immunocompetent adult patients hospitalized with community-acquired pneumococcal pneumonia.
      ]. Our study characterized a population of pneumococcal CAP patients who developed pulmonary complications, showing that they were younger and had fewer comorbidities (especially COPD) than patients without pulmonary complications. The concept of grouping pulmonary complications together comes from paediatricians who have studied children with and without complications of pneumococcal pneumonia [
      • Wexler ID.
      • Knoll S.
      • Picard E
      • et al.
      Clinical characteristics and outcome of complicated pneumococcal pneumonia in a pediatric population.
      ]. Indeed, two previous studies described several risk factors associated with an increased risk of pulmonary complications in children as follows: younger age, black race, low weight, and anaemia [
      • Obando I.
      • Munoz-Almagro C.
      • Arroyo LA
      • et al.
      Pediatric parapneumonic empyema, Spain.
      ,
      • Wexler ID.
      • Knoll S.
      • Picard E
      • et al.
      Clinical characteristics and outcome of complicated pneumococcal pneumonia in a pediatric population.
      ]. In our study, all of the analysed pulmonary complications clearly showed a positive association with parameters of CAP severity such as ICU admission and length of hospital stay. This finding supports our motivation to investigate prognostic factors for the development of pulmonary complications.
      Patients with complicated CAP had a lower rate of COPD and a higher rate of chronic liver disease. Other differential characteristics of complicated pneumonia were a higher inflammatory response (as assessed by higher CRP levels) and a higher percentage of bacteraemia, shock, ICU admission and MV than in uncomplicated pneumonia. The length of stay was higher for patients with complicated pneumonia, but the mortality rate did not significantly differ between the two study groups (9% vs. 8%). It is probable that all of these clinical and biological characteristics will, in the future, help clinicians to identify patients who may need a higher degree of monitoring and/or ICU care [
      • Liapikou A.
      • Ferrer M.
      • Polverino E
      • et al.
      Severe community-acquired pneumonia: validation of the Infectious Diseases Society of America/American Thoracic Society Guidelines to predict an intensive care unit admission.
      ].
      In the present study, we found that the rates of resistance to penicillin and macrolide were significantly higher in patients without pulmonary complications. A reduced rate of antibiotic resistance has also been observed in previous studies on adult patients with pneumococcal bacteraemia, in recent studies of adult patients with septic shock and of children with pulmonary complications of pneumococcal pneumonia [
      • Wexler ID.
      • Knoll S.
      • Picard E
      • et al.
      Clinical characteristics and outcome of complicated pneumococcal pneumonia in a pediatric population.
      ,
      • Garcia-Vidal C.
      • Ardanuy C.
      • Tubau F
      • et al.
      Pneumococcal pneumonia presenting with septic shock: host- and pathogen-related factors and outcomes.
      ].
      We were able to determine the pneumococcal serotype in 84 invasive strains. On comparison of serotype distribution in the two population groups, we found no statistically significant differences (p 0.42) in relation to pulmonary complications according to serotype group (PCV7 serotype vs. non-PCV7 serotypes); however, we found a trend for a higher rate of serotype 19A in patients with complicated pneumonia. Other studies have found that serotype 19A is more frequent among adults and children with IPD and complicated pneumococcal pneumonia [
      • Ardanuy C.
      • Tubau F.
      • Pallares R
      • et al.
      Epidemiology of invasive pneumococcal disease among adult patients in Barcelona before and after pediatric 7-valent pneumococcal conjugate vaccine introduction, 1997–2007.
      ,
      • Garcia-Vidal C.
      • Ardanuy C.
      • Tubau F
      • et al.
      Pneumococcal pneumonia presenting with septic shock: host- and pathogen-related factors and outcomes.
      ]. In a landmark study, the incidence of IPD in adults was found to have decreased since the PCV7 vaccine was introduced. In contrast, the incidence of more virulent serotypes (3 and 19A) had increased in parallel [
      • Chibuk TK.
      • Robinson JL.
      • Hartfield DS.
      Pediatric complicated pneumonia and pneumococcal serotype replacement: trends in hospitalized children pre and post introduction of routine vaccination with Pneumococcal Conjugate Vaccine (PCV7).
      ]. A recently published study by Garcia-Vidal et al. [
      • Garcia-Vidal C.
      • Ardanuy C.
      • Tubau F
      • et al.
      Pneumococcal pneumonia presenting with septic shock: host- and pathogen-related factors and outcomes.
      ] showed that serotype 3 was more frequent in patients with pneumococcal pneumonia presenting with shock. All of these data are crucial for the development of new vaccines. Fortunately, the new conjugate 13-valent pneumococcal vaccine includes serotypes 1, 3, and 19A, and is currently being tested in adults aged over 65 years [
      • Reinert R.
      • Jacobs MR.
      • Kaplan SL.
      Pneumococcal disease caused by serotype 19A: review of the literature and implications for future vaccine development.
      ].
      Chronic liver disease was one of the factors associated with an increased risk of pulmonary complications in the multivariate analysis. Another study by our group has shown that chronic liver disease is a risk factor for complications and poor outcomes [
      • de Roux A.
      • Cavalcanti M.
      • Marcos MA
      • et al.
      Impact of alcohol abuse in the etiology and severity of community-acquired pneumonia.
      ]. An elevated CRP level (≥18 mg/dL) at admission was also found to be a risk factor for the development of pulmonary complications. Chalmers et al. [
      • Chalmers JD.
      • Singanayagam A.
      • Hill AT.
      C-reactive protein is an independent predictor of severity in community-acquired pneumonia.
      ] found that low admission CRP levels were associated with negative predictive value for 30-day mortality, MV, inotropic support, and complicated pneumonia. In the other hand we found that eleveated creatinine (>1.5mg/dL) at atmission was another risk factor for pulmonary complications. This parameter is a marker of a bad outcome, as has been described previously [
      • Lim WS.
      • van der Eerden MM.
      • Laing R
      • et al.
      Defining community acquired pneumonia severity on presentation to hospital: an international derivation and validation study.
      ]. In the same analysis, we found that only COPD was a protective factor against the development of pulmonary complications. Why COPD is a protective factor against pulmonary complications is difficult to explain. However, in a recent cellular study by our group [
      • Gutierrez P.
      • Closa D.
      • Piner R
      • et al.
      Macrophage activation in exacerbated chronic obstructive pulmonary disease with and without community-acquired pneumonia.
      ], we observed the activation of different phenotype macrophages in CAP with and without COPD, indicating different inflammatory responses. This different type of activation induces different inflammatory responses, and may be involved in the better outcome of CAP observed in some studies when COPD presents simultaneously [
      • Gutierrez P.
      • Closa D.
      • Piner R
      • et al.
      Macrophage activation in exacerbated chronic obstructive pulmonary disease with and without community-acquired pneumonia.
      ]. Similarly, Strassburg et al. [
      • Strassburg A.
      • Luers A.
      • Dalhoff K.
      Decreased apoptosis of pulmonary PMN in COPD patients with community-acquired pneumonia.
      ] found decreased apoptosis of pulmonary neutrophils in COPD patients with CAP, indicating an increased inflammatory response to the bacterial load in these patients. COPD was also found to be a protective factor against non-responding pneumonia in another study from our group investigating factors associated with treatment failure in CAP [
      • Menendez R.
      • Torres A.
      • Zalacain R
      • et al.
      Risk factors of treatment failure in community acquired pneumonia: implications for disease outcome.
      ].
      Investigation of antibiotic treatment in our population showed a significantly higher rate of β-lactam plus fluoroquinolone treatment in patients with complicated CAP. In contrast, we observed a higher rate of fluoroquinolone monotherapy in patients with uncomplicated CAP. These differences can probably be explained by the disease severity, which influenced clinicians to use a potent antibiotic combination for complicated CAP and monotherapy for uncomplicated CAP. In the study period, our hospital routinely followed the recommendations of the Spanish Society of Pulmonology and Thoracic Surgery for the empirical treatment of CAP [
      • Menendez R.
      • Torres A.
      • Zalacain R
      • et al.
      Guidelines for the treatment of community-acquired pneumonia: predictors of adherence and outcome.
      ]. Following these guidelines (β-lactam plus macrolide or quinolone as monotherapy), we found that initial antibiotic treatment was adequate in patients for whom an antibiogram was available.
      The strengths of our study are as follows: (i) a large population of consecutive patients included over a period of 9 years; (ii) the application of the concept of pulmonary complications in adults for the first time in CAP, following what has been previously published for the paediatric population [
      • Tan TQ.
      • Mason Jr, EO
      • Barson WJ
      • et al.
      Clinical characteristics and outcome of children with pneumonia attributable to penicillin-susceptible and penicillin-nonsusceptible Streptococcus pneumoniae.
      ] the concept of complicated pneumonia could be debated but in our opinion it represents a CAP subpopulation that can be distinguished specifically; and (iii) the study of antibiotic resistance in most of the strains, and serotype information for the last 4 years. A limitation of the study is the lack of information about the time to the first dose of antibiotic, a variable that may potentially influence mortality. Moreover, serotyping results were limited to the years 2006–2009.
      In summary, our study describes a subpopulation of hospitalized pneumococcal pneumonia patients in whom the mortality did not differ despite the higher severity of pneumonia. COPD as a comorbidity was the only protective factor against pulmonary complications. Finally, no significant differences were observed between the serotype distributions of complicated and uncomplicated pneumonia.

      Financial Disclosure

      None.

      Acknowledgements

      For logistic support: 2009 Support to Research Groups of Catalunya 911; Ciber de Enfermedades Respiratorias (CibeRes CB06/06/0028); Ciberes es una iniciativa del Instituto de Salud Carlos III—Ministerio de Ciencia e Innovacion, Spain; and Institut de investigaciones Biomédicas August Pi i Sunyer.

      Transparency Declaration

      None of the authors have any conflict of interests to declare.

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