Community Acquired Pneumonia (CAP)社区获得性肺炎

1、Community Acquired Pneumonia (CAP)Bradley K. Harrison, M.D.1CAP definedPneumonia not acquired in a hospital or a long-term care facilityHospital acquired pneumoniaHealthcare associated pneumonia: other healthcare facilities such as nursing homes, dialysis centers, and outpatient clinics2Introduction

2、 Estimated 5.6 million cases of CAP occur annually in the United StatesEstimated total annual cost for CAP in the United States is $8.4 billion92% of cost with inpatient therapyBecause CAP is the only acute respiratory tract infection in which there is increased mortality if antibiotic therapy is de

3、layed, diagnostic and treatment decisions need to be made accurately and efficientlyMortality rate among hospitalized patients with CAP varies each year and can reach 35%3EpidemiologyUnclear because few population-based statistics for CAP alone are availableCenter for Disease Control and Prevention

4、(CDC) combines pneumonia with influenza when collecting data on morbidity and mortalityIn 2001, influenza and pneumonia combined were the 7th leading cases of death in the U.S.Down from 6th in previous yearsDeath rate of 21.8 per 100,000 patients4Clinical PresentationPneumonia is an inflammation or

5、infection of the lungs that causes them to function abnormally Classified as typical or atypical, although the clinical presentations are often similarSeveral symptoms commonly present in patients with pneumoniaApproximately 20-33% of episodes result in hospitalization 5Etiology Typical: up to 70%Us

6、ually caused by Streptococcus pneumoniaeAtypical: 30-40%“My Lungs Contain Viruses”Mycoplasma pneumoniaeLegionella pneumophilaChlamydia pneumoniaeViruses: Influenza, AdenovirusMay be co-pathogens in other cases6SymptomsCough, fever, chills, fatigue, dyspnea, rigors, and pleuritic chest painDepending

7、on the pathogen, cough may be persistent and dry, or it may produce sputumOther presentations may include headache and myalgiaCertain etiologies, such as legionella, also may produce gastrointestinal symptomsSymptoms at presentation are not useful in distinguishing CAP from respiratory illnesses wit

8、h other causes7Diagnosis: Physical ExaminationDullness to percussion of chest, crackles or rales on auscultation, bronchial breath sounds, tactile fremitus, and egophany (“E” to “A” changes)Patient may also be tachypneicPatients with typical pneumonia are more likely to present with dyspnea and bron

9、chial breath sounds on auscultation8Diagnosis: RadiographyCXR (PA and Lateral): American Thoracic Society (ATS) guidelines, “all patients with suspected CAP should have a chest radiograph to establish the diagnosis and identify complications (pleural effusions, multilobar disease)”Lobar consolidatio

10、n more common in typical pneumoniaBilateral, diffuse infiltrates commonly seen in atypical pneumoniaHowever, radiologists cannot reliably differentiate bacterial from nonbacterial pneumonia on the basis of the radiographic appearance If performed early in the course of the disease, may be negativeTh

11、e sensitivity of chest radiography depends greatly on pretest probability 947-year-old smoker presented after just a few hours of rigors and productive coughDespite clinical signs of right upper zone consolidation, chest x-ray showed only minor abnormalitiesEmpirical therapy for community-acquired p

12、neumonia was begun1012 hours laterChest x-ray showed consolidation in the right upper lobe consistent with the earlier clinical signsS. pneumoniae was isolated from blood culturesThe patient recovered fully11Diagnosis: Radiography (cont.)CTCT scan could be performed in patients with a negative chest

13、 radiograph when there is a high clinical suspicion for pneumoniaCT scan, especially high resolution CT (HRCT), is more sensitive than plain films for the evaluation of interstitial disease, bilateral disease, cavitation, empyema, and hilar adenopathyThis technology is not generally recommended for

14、routine use because the data for its use in CAP are limited, the cost is high, and there is no evidence that this improves outcomeThus, a chest radiograph is the preferred method for initial imaging, with CT scan or MRI reserved for further anatomical definition12Diagnosis: Laboratory Tests Historic

15、ally: WBC, sputum cultures, two sets of blood cultures, and urine antigensSputum samples are adequate in only 52% of patients with CAP, and only 44 % of those samples contain pathogensLikely due to problems with retrieving samples from lower respiratory tract, previous antibiotics, contamination fro

16、m upper airways, or viral etiologyPositive blood cultures obtained in only 5-10% of patients, including those with severe diseasePositive blood culture has no correlation with severity of illness or outcomeCurrent ATS guidelines recommend that patients hospitalized for suspected CAP receive 2 sets o

17、f blood cultures13Diagnosis and treatment of community-acquired pneumonia: Am Fam Physician. 2006 Feb 1;73(3):442-50. 14TreatmentInitial treatment of CAP is based on physical examination findings, laboratory results, and patient characteristicsAge, chronic illnesses, smoking history, history of the

18、illnessTherapy for pneumonia is empiric because specific pathogens usually are not identified at the time treatment is initiatedPhysicians should begin their treatment decisions by assessing the need for hospitalization using a prediction tool for increased mortality, combined with clinical judgment

19、Pneumonia Severity Index15Pneumonia Severity Index (PSI)PSI was derived and validated as part of the Pneumonia Patient Outcomes Research Team (PORT) prospective cohort study for the purpose of identifying patients with CAP at low risk for mortality The Pneumonia PORT prediction rule used a derivatio

20、n cohort of 14,199 inpatients with CAP; it was independently validated in 38,039 inpatients with CAP and in 2,287 inpatients and outpatients prospectively The PSI rule stratified adults with radiographic evidence of pneumonia into five classes for risk of death from all causes within 30 days of pres

21、entation One limitation in the derivation of this rule was that it included mostly patients seen in a hospital emergency department, and included few outpatients who were evaluated in a physicians office and sent home 16Pneumonia Severity Index (PSI)17Treatment: Outpatient vs. InpatientChoosing betw

22、een outpatient and inpatient treatment is a crucial decision because of the possible risk of deathDecision influences diagnostic testing and medication choices, as well as a psychological impact on patients and familiesAverage costInpatient: $7,500Outpatient: $150-350Based on age, co-morbidities, an

23、d the severity of presenting disease18Treatment: Outpatient vs. Inpatient (cont.)Physicians tend to overestimate a patients risk of death; many low-risk patients could be treated safely as outpatientsBy using Pneumonia Severity Index (PSI), 26-31% of hospitalized patients were good outpatient candid

24、atesAn additional 13-19% only needed brief hospital observationPSI can serve as a general guideline, clinical judgment should always supersede prognostic score19Pharmacotherapy: OutpatientConsensus guidelinesATS, Infectious Disease Society of America, and Canadian Guidelines for the Initial Manageme

25、nt of Community-Acquired PneumoniaEmpiric oral therapy with macrolides, doxycycline, or an oral beta lactam (amoxicillin, cefuroxime ceftin, or amoxicillin/clavulanate augmentin), or a flouroquinoloneTherapeutic Working Group of the CDCUse flouroquinolones sparingly because of resistance concernsDur

26、ation of therapyS. pneumoniae: 7-10 days or until afebrile 3 daysBacteremic: 10-14 daysMycoplasma/Chlamydia pneumoniae: 10-14 days, up to 21 daysLegionella: 10-21 days20Pharmacotherapy: Outpatient (cont.)Several classes of antibiotics are effective against atypical pathogensC. pneumoniae and Legione

27、lla species are intracellular organisms and M. pneumoniae lacks a cell wall, beta lactams are not effectiveErythromycin and tetracycline have been traditional choices for atypical CAPNewer macrolides (azithromycin zithromax and clarithromycin biaxin) have good atypical activity and are generally are

28、 better tolerated than erythromycinDoxycycline (Vibramcyin) is effective, associated with fewer gastrointestinal side effects, and is a less expensive alternativeFlouroquinolones have demonstrated excellent activity against atypicals and have one-daily dosing and excellent bioavailability21Pharmacot

29、herapy: Outpatient (cont.)The Sanford Guide to Antimicrobial Therapy 2006 36th Ed.CAP, not hospitalized, no comorbidities*Azithro 0.5g PO x 1, then 0.25g PO QDAzithro-ER 2g x 1 (2g /60mL single dose bottle)Clarithro 500mg PO BIDClarithro-ER 1g PO Q24hDoxy 100mg PO BID* Alcoholism, bronchiectasis, CO

30、PD, IVDU, Post-CVA aspiration, post-obstruction of bronchi, post-viral22Pharmacotherapy: Outpatient (cont.)The Sanford Guide to Antimicrobial Therapy 2006 36th Ed.CAP, not hospitalized, with comorbiditiesRespiratory flouroquinoloneGati 400mg PO q24h, Gemi 320mg PO q24h, Levo 750mg PO q24h, Moxi 400m

31、g PO q24hTelithro 800mg PO q24hAzithro/Clarithro + HD Amox, HD AM-CL, cefdinir, cefpodoxime, cefprozil23Pharmacotherapy: InpatientAntibiotic therapy should be initiated within 4 hours of hospitalizationIntravenous beta lactam (cefotaxime claforan or ceftriaxone rocephin) plus a macrolide or a combin

32、ation of ampicillin/sulbactam (unasyn) plus a macrolide or a fluoroquinolone aloneAfter clinically stable (T100.0, HR100, RR90, O2 sat90%) and able to tolerate oral intake, may be switched to oral antibiotics for remainder of therapySave money, earlier discharge, minimizes risk of nosocomial infecti

33、ons24Pharmacotherapy: Inpatient (cont.)The Sanford Guide to Antimicrobial Therapy 2006 36th Ed.CAP, hospitalized, NOT in ICU, no comorbiditiesCeftriaxone 2g IV q24h + Azithro 500mg IV q24hAge 65: Ceftriaxone 1g IV q24hCAP, hospitalized, NOT in ICU, comorbiditiesGati 400mg IV q24h, Levo 750mg IV q24h

34、, Moxi 400mg IV q24h2526FlouroquinolonesConservative use is recommended to minimize resistance patternsNew flouroquinolones (levofloxacin, gatifloxacin, moxifloxacin) should be used only when patients have failed recommended first-line regimens, are allergic to alternative agents, or have a document

35、ed infection with highly drug-resistant pneumococci27Pneumococcal ResistanceS. pneumoniae accounts for 60-70% of all bacterial CAPAffects all patient groups and can be fatalAlarming rate of resistance to many commonly used antibioticsPCN uncommon before 1990Resistance classified as intermediate or h

36、igh-levelIntermediate: 28%High-level: 16%Nation-wide28Antibiotics tested against Streptococcus pneumoniae isolatesResistance rates averaged across all patient groups29Cost-effective CareWhen choosing a treatment, it is essential to compare costs and outcomes of all recommended drug therapiesEvaluati

37、on should lead to a decision that will maximize the value of health care services, not simply reduce the costs of drug therapyOverall cost of each therapy should be obtained by comparing the end cost with the probability of achieving a positive outcome30Antimicrobial Therapies for CAPAgentDosageCost

38、 per course (generic)Common adverse reactionsCefotaxime (Claforan)Cefpodoxime (Vantin)Cefprozil (Cefzil)Ceftriaxone (Rocephin)Cefuroxime (Ceftin)1 g IV every six to eight hours200 mg orally twice per day500 mg orally twice per day1 g IV every 24 hours500 mg orally twice per day0.75 to 1.5 g IV every

39、 eight hours$355 (330)124 (110)192392219 oral250 to 358 IVMild diarrheaRashClindamycin (Cleocin)300 mg orally every six hours600 mg IV every eight hours238 (148 to 168) oral250 IVMild diarrheaAbdominal painPseudomembranous colitisRashGatifloxacin (Tequin)Levofloxacin (Levaquin)Moxifloxacin (Avelox)4

40、00 mg orally or IV once per day500 mg orally or IV once per day400 mg orally once per day98 oral, 382 IV56 oral, 438 IV107Mild diarrheaNauseaVomitingConstipationDizzinessHeadacheAzithromycin (Zithromax)Clarithromycin (Biaxin)Erythromycin500 mg orally for one dose, then250 mg once per day for four doses500 mg IV every 24 hours500 mg