Severe community-acquired pneumonia. Risk factors and follow-up epidemiology.

The aim of the study was to determine risk factors for severe community-acquired pneumonia (CAP) as well as to compare microbial patterns of severe CAP to a previous study from our respiratory intensive care unit (ICU) originating from 1984 to 1987. Patients admitted to the ICU according to clinical judgment were defined as having severe CAP. For the study of risk factors, a hospital-based case-control design was used, matching each patient with severe CAP to a patient hospitalized with CAP but not requiring ICU admission. Microbial investigation included noninvasive and invasive techniques. Overall, 89 patients with severe CAP were successfully matched to a control patient. The presence of an alcohol ingestion of >/= 80 g/d (odds ratio [OR] 3.9, 95% confidence interval [CI] 1.4 to 10.6, p = 0.008) was found to be an independent risk factor for severe CAP and prior ambulatory antimicrobial treatment (OR 0.37, 95% CI 0.17 to 0.79, p = 0.009) to be protective. Streptococcus pneumoniae (24%) continued to be the most frequent pathogen; however, 48% of strains were drug-resistant. "Atypical" bacterial pathogens were significantly more common (17% versus 6%, p = 0.006) and Legionella spp. less common (2% versus 14%, p = 0.004) than in our previous study, whereas gram-negative enteric bacilli (GNEB) and Pseudomonas aeruginosa continued to represent important pathogens (6% and 5%, respectively). Our findings provide additional evidence for the importance of the initiation of early empiric antimicrobial treatment for a favorable outcome of CAP. Variations of microbial patterns are only in part due to different epidemiological settings. Therefore, initial empiric antimicrobial treatment will also have to take into account local trends of changing microbial patterns.     

Severe community-acquired pneumonia: current outcomes, epidemiology, etiology, and therapy

Severe community-acquired pneumonia is a clinical diagnosis with a significant impact on healthcare management around the world, with the highest morbidity and mortality of all of the forms of community-acquired pneumonia. Patients with severe pneumonia usually require intensive care unit management, including vasopressors or mechanical ventilation. Early clinical suspicion and prompt empiric antimicrobial therapies are mandatory in patients with severe pneumonia. A number of recent studies and guidelines addressing these issues have been published, and they will be reviewed in this article.     

社区获得性呼吸道感染主要致病菌及其耐药性变化

肺炎链球菌(SP)和肺炎支原体(MP)是我国社区获得性肺炎(CAP)的最常见病原体,另外,细菌合并非典型病原体的混合感染亦不可忽视。SP对大环内酯类抗菌药物的耐药率迅速增加,并且其对青霉素的耐药性仍呈上升趋势。MP对大环内酯类抗菌药物的耐药率也在增加。而喹诺酮类药物对SP及非典型病原体仍具有较强抗菌活性。金黄色葡萄球菌是CAP的少见病原体,但是随着社区获得性耐甲氧西林金黄色葡萄球菌在世界范围内的增加,已引起了临床的重视。     

Genetics of community-acquired pneumonia

The variable clinical presentation of community-acquired pneumonia (CAP) suggests a genetic predisposition. Specific mutations or polymorphisms in host response genes such as pattern recognition molecules (PRMs), inflammatory molecules, and the coagulation system are likely to play a role in this variable response to CAP. Mannose-binding lectin polymorphisms appear to play a more dominant role in CAP than other PRMs, such as the Toll-like receptors (TLRs). The role of tumor necrosis factor (TNF) and lymphotoxin alpha (LTA) polymorphisms remain unclear despite extensive study whereas interleukin (IL)-10 and IL-1 receptor antagonist polymorphisms appear to play an important role in the anti-inflammatory response. Coagulation gene polymorphisms are likely important as well. The real value of these genetic studies in CAP and other severe infections will be when the management of an individual patient can be optimized by therapy based on the individual's genotype for molecules important in outcome.     

Epidemiology of community-acquired pneumonia in the elderly

The attack rate for pneumonia increases with increasing age and with residence in a nursing home. The rate of hospitalization of Halifax County, Nova Scotia, Canada, residents with pneumonia was 1 in 1,000, while for nursing home residents it was 33 in 1,000. The overall mortality rate for community-acquired pneumonia requiring hospitalization was 21.9%. Mortality was age-related: Seven percent of those 30 years of age or younger died, while 38% of those in the 81 to 90 year age group died. Comorbidities increased with increasing age from 0.73 +/- 0.81 for those 30 years old or younger to 2.75 +/- 1.47 for those 71 to 80 years of age. The most common comorbidities were chronic obstructive pulmonary disease, ischemic heart disease, hypertension, diabetes mellitus, malignancy, alcoholism, and neurological disease. The acquired immunodeficiency syndrome was a significant comorbidity among those 50 years of age or younger. Age-dependent trends were observed in the use of antimicrobial therapy: Cefamandole and aminoglycosides were prescribed more frequently with increasing age, whereas after the age of 61 years, the use of erythromycin declined. Penicillin usage was not age-dependent. Resource (hemograms, chest radiographs, blood chemistry, blood gases, and sputum culture) use peaked at the 50 to 60 year age group.     

Etiology of community-acquired pneumonia

Community-acquired pneumonia (CAP) is a serious lower respiratory tract infection associated with significant morbidity and mortality that is characterized by disputes over diagnostic evaluations and therapeutic decisions. With the widespread use of broad-spectrum antimicrobial agents and the increasing number of immunocompromised hosts, the etiology and the drug resistance patterns of pathogens responsible for CAP have changed. Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis remain the leading causes of CAP in immunocompetent patients. Opportunistic infections with organisms such as Pneumocystis jiroveci and Mycobacterium tuberculosis and other opportunistic fungal pneumonias should also be considered in the differential diagnosis of CAP in immunocompromised patients. This article examines the current peer-reviewed literature on etiology, risk factors, and outcomes of patients with CAP.     

Prognostic significance of platelet count changes during hospitalization for community-acquired pneumonia

The prognostic significance of platelet count (PC) changes during hospitalization for community-acquired pneumonia (CAP) has not been investigated. For 976 adults, clinical data during hospitalization for CAP and all-cause mortality following discharge were compared according to ΔPC (PC on discharge minus PC on admission): groups A (declining PC, ΔPC < ?50 × 10⁹/l), B (stable PC, ΔPC ± 50 × 10⁹/l), and C (rising PC, ΔPC >50 × 10⁹/l), and according to the presence of thrombocytopenia, normal PC, and thrombocytosis on admission/discharge. Groups A, B, and C comprised 7.9%, 46.5%, and 45.6% of patients, respectively. On hospital admission/discharge, thrombocytopenia, normal PC, and thrombocytosis were observed in 12.8%/6.4%, 84.1%/84.4%, and 3.1%/9.2% of patients, respectively. The respective 90-day, 3-year, and total (median follow-up of 54 months) mortality rates were significantly higher: in group A (40.3%, 63.6%, and 72.7%), compared to groups B (12.3%, 31.5%, and 39.0%) and C (4.9%, 17.3%, and 25.4%), p < 0.001; and in patients with thrombocytopenia at discharge (27.4%, 48.4%, and 51.6%), compared to those with normal PC (10.2%, 26.9%, and 35.4%) and thrombocytosis (8.9%, 17.8%, and 24.4%) at discharge (p < 0.001). Mortality rates were comparable among groups with thrombocytopenia, normal PC, and thrombocytosis at admission (p = 0.6). In the entire sample, each 100 × 10⁹/l increment of ΔPC strongly predicted lower mortality (p < 0.001, relative risk 0.73, 95% confidence interval 0.64?0.83). In conclusion, PC changes are common among CAP inpatients. Rising PC throughout hospitalization is a powerful predictor of better survival, while declining PC predicts poor outcome. Evaluation of PC changes during hospitalization for CAP may provide useful prognostic information.     

Treatment failure in community-acquired pneumonia

Treatment failure (TF) is defined as a clinical condition with inadequate response to antimicrobial therapy. Clinical response should be evaluated within the first 72 h of treatment, whereas infiltrate images may take up to 6 weeks to resolve. Early failure is considered when ventilatory support and/or septic shock appear within the first 72 h. The incidence of treatment failure in community-acquired pneumonia is 10 to 15%, and the mortality is increased nearly fivefold. Resistant and unusual microorganisms and noninfectious causes are responsible for TF. Risk factors are related to the initial severity of the disease, the presence of comorbidity, the microorganism involved, and the antimicrobial treatment implemented. Characteristics of patients and factors related to inflammatory response have been associated with delayed resolution and poor prognosis. The diagnostic approach to TF depends on the degree of clinical impact, host factors, and the possible cause. Initial reevaluation should include a confirmation of the diagnosis of pneumonia, noninvasive microbiological samples, and new radiographic studies. A conservative approach of clinical monitoring and serial radiographs may be recommended in elderly patients with comorbid conditions that justify a delayed response. Invasive studies with bronchoscopy to obtain protected brush specimen and BAL are indicated in the presence of clinical deterioration or failure to stabilize. BAL processing should include the study of cell patterns to rule out other noninfectious diseases and complete microbiological studies. The diagnostic yield of imaging procedures with noninvasive and invasive samples is up to 70%. After obtaining microbiological samples, an empirical change in antibiotic therapy is required to cover a wider microbial spectrum.     

Adjunctive therapy in community-acquired pneumonia

Despite potent antibiotics, community-acquired pneumonia (CAP) remains the most common cause of death from infection and the eighth overall leading cause of death in the United States. For this reason, adjunctive therapeutic measures directed at the host response rather than the pathogen are attractive. The immunomodulatory effects of macrolide antibiotics may play a significant role in management of severe CAP. The existing literature does not demonstrate a clear benefit for corticosteroids, but larger prospective randomized trials are needed. Nonsteroidal antiinflammatory drugs may benefit oxygenation but have no documented effect on mortality. Statin use before CAP diagnosis is associated with improved outcome but requires further research to determine if initiation at the time of diagnosis will affect outcome positively. Activation of the coagulation system appears to be a major pathophysiological event in severe pneumonia, but neither drotrecogin alfa activated nor tifacogin (recombinant tissue factor pathway inhibitor) have demonstrated a survival benefit. Other therapies have theoretical benefit but are not yet in the stage of clinical trials.     

莫西沙星与左氧氟沙星治疗社区获得性肺炎的临床研究

目的探讨莫西沙星和左氧氟沙星治疗社区获得性肺炎的疗效。方法选择社区获得性肺炎患者120例,随机分成莫西沙星组60例和左氧氟沙星组60例,分别给予治疗7 d,运用药物经济学的成本-效果分析方法进行评价。结果莫西沙星组和左氧氟沙星组治疗有效率分别为98.33%和71.67%,细菌清除率分别为91.67和65.57%,不良反应发生率分别为8.33%和13.33%,成本-效果比分别为21.87%和10.26%。结论莫西沙星组的治疗有效率和细菌清除率明显优于左氧氟沙星组（P〈0.01）,莫西沙星治疗社区获得性肺炎在临床治疗中是优选方案。     

Severe community-acquired pneumonia in adults

Patients with severe community acquired pneumonia (CAP) need continuous surveillance and monitoring at intensive care units (ICU), where they can receive specialized support as mechanical ventilation and/or hemodynamic support. Patients that require ICU admittance represent 10 to 30% of all patients interned because a pneumonia. In this category, high complication rate, prolonged hospital stay and high mortality rate are the rule. The American Thoracic Society (ATS) criteria for severe pneumonia establishes the following main criteria: necessity of mechanical ventilation and presence of septic shock; minor criteria: systolic blood pressure < 90 mmHg, radiological multilobar involvement and PaO2/FiO2 < 250 mmHg. British Thoracic Society (BTS) criteria for severe CAP are: respiratory rate over 30 breaths/min, diastolic blood pressure under 60 mmHg, BUN > 20 mg/dl and mental confusion. In all patients with CAP it is recommended the evaluation of its severity at admission. This evaluation should be done in conjunction with an experienced physician, and if criteria for poor prognosis are met, an early admission to ICU is recommended. ATS and BTS modified criteria (CURB) are useful in this procedure. In severely ill patients with CAP it is recommended to perform the following microbiological analysis: sputum Gram stain and culture, blood culture, pleural fluid Gram stain and culture, if present and tapped, Legionella pneumophila urine antigen test, influenza A and B antigen detection tests (epidemic period: autumn and winter), and serology for atypical bacteria (Mycoplasma pneumoniae and Chlamydia pneumoniae).     

A comparison between time to clinical stability in community-acquired aspiration pneumonia and community-acquired pneumonia

Antimicrobial therapy has been the main stay of therapy of community-acquired aspiration pneumonia (CAAP), but the duration of treatment has not been established. The objective of this study was to describe the time to reach clinical stability in patients with aspiration pneumonia compared to community-acquired pneumonia (CAP). A retrospective case control study at two university affiliated centers encompassing 329 consecutive patients admitted with CAAP and 329 consecutive patients with CAP was conducted between 2007 and 2011. While the median time to stability for patients with CAP was distributed around a median of 4 days, there was a bimodal distribution for time to clinical stability in patients with CAAP with dual peaks at days 2 and 5, respectively. CAAP patients who required more than 2 days to achieve clinical stability had a higher mortality rate compared to those with 2 days or less [odds ratio (OR) 5.95, 95% CI 2.85–12.4], and a longer hospital stay (6.6 ± 5.8 vs. 3.9 ± 1.2 days; p < 0.001). None of the CAAP patients who achieved clinical stability in 2 days or less was transferred to a higher level of care. In a multivariate analysis, time to clinical stability was found to be an independent predictor of outcome in patients with CAAP (OR 2.59, 95% CI 2.02–3.32). Normalization of vital signs in aspiration pneumonia follows a distinct pattern from that of patients with CAP. Time to achieve clinical stability may assist in identifying CAAP patients who are likely to require a shorter hospital stay and a shorter course of antimicrobial therapy.