呼吸机相关性肺炎（vap）的流行病学及预防（英文ppt）preventionof ventilator associated pneumonia （vap）

Tracking NI has become difficult nShorter inpatient stays (average postoperative stay, now approximately 5 days, is usually shorter than the 5- to 7-day incubation period for S. aureus surgical wound infections) nSurveillance systems are optional to hospitals with infection-control programs Prevention of Ventilator Associated Pneumonia (VAP) AACN VAP Practice Alert Lecture Content nEpidemiology of VAP nPrevention strategies nHOB elevation nVentilator equipment changes nContinuous removal of subglottic secretions nHandwashing AACN VAP Practice Alert Epidemiology of Ventilator Associated Pneumonia (VAP) AACN VAP Practice Alert Nosocomial Pneumonias nAccount for 15% of all hospital associated infections nAccount for 27% of all MICU acquired infections nPrimary risk factor is mechanical ventilation (risk 6 to 21 times the rate for nonventilated patients) CDC Guideline for Prevention of Healthcare Associated Pneumonias 2003 Cook et al, Ann Intern Med 1998;129:433 AACN VAP Practice Alert Critical Care Interventions Increase Susceptibility to Nosocomial Pneumonias Tracheal Colonization Altered Host Defenses Increased Nosocomial Pneumonias Intubation AACN VAP Practice Alert VAP Etiology nMost are bacterial pathogens, with Gram negative bacilli common: nPseudomonas aeruginosa nProteus spp nAcinetobacter spp nStaphlococcus aureus nEarly VAP associated with non-multi- antibiotic-resistant organisms nLate VAP associated with antibiotic- resistant organism AACN VAP Practice Alert Significance of Nosocomial Pneumonias nMortality ranges from 20 to 41%, depending on infecting organism, antecedent antimicrobial therapy, and underlying disease(s) nLeading cause of mortality from nosocomial infections in hospitals CDC Guideline for Prevention of Healthcare Associated Pneumonias 2003 Heyland et al, Am J Respir Crit Care Med 1999;159:1249 Bercault et al, Crit Care Med 2001;29:2303 AACN VAP Practice Alert Significance of Nosocomial Pneumonias nIncreases ventilatory support requirements and ICU stay by 4.3 days nIncreases hospital LOS by 4 to 9 days nIncreases cost - Heyland et al, Am J Respir Crit Care Med 1999;159:1249 Craven D. Chest 2000;117:186-187S Rello et al, Chest 2002;122:2115 AACN VAP Practice Alert VAP Prevention AACN VAP Practice Alert Continuous Removal of Subglottic Secretions nUse an ET tube with continuous suction through a dorsal lumen above the cuff to prevent drainage accumulation CDC Guideline for Prevention of Healthcare Associated Pneumonias 2003 Kollef et al, Chest 1999;116;1339 AACN VAP Practice Alert HOB Elevation HOB at 30-45o CDC Guideline for Prevention of Healthcare Associated Pneumonias 2003 Drakulovic et al, Lancet 1999;354:1851 Frequency of Equipment Changes Ventilator Tubing Inner Cannulas of Trachs Ambu Bags No Routine Changes Not Enough Data Between Patients CDC Guideline for Prevention of Healthcare Associated Pneumonias 2003 AACN VAP Practice Alert Handwashing What role does handwashing play in nosocomial pneumonias? Albert, NEJM 1981; Preston, AJM 1981; Tablan, 1994 AACN VAP Practice Alert VAP PreventionVAP Prevention All recommendations are level IA CDC Guideline for Prevention of Healthcare Associated Pneumonias 2003 AACN Practice Alert for VAP, 2004 Wash hands before and after suctioning, touching ventilator equipment, and/or coming into contact with respiratory secretions. AACN VAP Practice Alert Use a continuous subglottic suction ET tube for intubations expected to be 24 hours Keep the HOB elevated to at least 30 degrees unless medically contraindicated VAP PreventionVAP Prevention All recommendations are level II CDC Guideline for Prevention of Healthcare Associated Pneumonias 2003 AACN Practice Alert for VAP, 2004 AACN VAP Practice Alert No Data to Support These Strategies nUse of small bore versus large bore gastric tubes nContinuous versus bolus feeding nGastric versus small intestine tubes nClosed versus open suctioning methods nKinetic beds CDC Guideline for Prevention of Healthcare Associated Pneumonias 2003 AACN VAP Practice Alert Potential consequences of inappropriate antibiotic therapy nInappropriate empiric antibiotic therapy can lead to increases in: nmortality nmorbidity nlength of hospital stay ncost burden nresistance selection Inappropriate antibiotic therapy nInappropriate antibiotic therapy can be defined as one or more of the following: nineffective empiric treatment of bacterial infection at the time of its identification nthe wrong choice, dose or duration of therapy nuse of an antibiotic to which the pathogen is resistant Evidence of improved clinical outcomes with appropriate empiric antibiotic therapy nA number of studies have demonstrated the benefits of early use of appropriate empiric antibiotic therapy for patients with nosocomial infections nSeveral key clinical studies are reviewed in the following slides Inappropriate antibiotic therapy is a risk factor for mortality among patients in the intensive care unit (ICU) nInfection-related mortality rates were assessed in a prospective cohort, single-centre study of 2000 patients admitted to medical/surgical ICUs n655 patients had a clinically recognised infection: n442 (67.5%) had a community-acquired infection n286 (43.7%) developed a nosocomial infection n73 (11.1%) had both community-acquired and nosocomial infections n169 (25.8%) patients received inappropriate initial antimicrobial treatment Kollef et al. Chest 1999;115:462474 Inappropriate antibiotic therapy is a risk factor for mortality among patients in the ICU Kollef et al. Chest 1999;115:462474 Hospital mortality (%) 0 20 50 60 Appropriate therapyInappropriate therapy 40 30 10 All causesInfectious disease-related p72 hours) with clinically confirmed VAP underwent BAL within 24 hours of diagnosis n107 patients received antibiotics prior to bronchoscopy n25 patients received antibiotics immediately after bronchoscopy nMortality rates were assessed in relation to the adequacy and time of initiation of antibiotic therapy Luna et al. Chest 1997;111:676685 Luna et al. Chest 1997;111:676685 Appropriate early antibiotic therapy reduces mortality rates in patients with suspected VAP (Study 1) Mortality (%) Pre-BALPost-BALPost-culture result 0 60 100 20 40 80 p50% of S. aureus isolates Aucken et al. J Antimicrob Chemother 2002;50:171175 Risk factors for colonisation or infection with MRSA in hospitals Chambers. Emerg Infect Dis 2001;7:178182 Admission to an ICUAdmission to an ICU SurgerySurgery Prior antibiotic exposurePrior antibiotic exposure Exposure to an MRSA-colonised patientExposure to an MRSA-colonised patient Emergence of MRSA in the community nMRSA in hospitals leads to an associated rise in incidence in the community nCommunity-acquired MRSA strains may be distinct from those in hospitals nIn a hospital-based study, 40% of MRSA infections were acquired prior to admission nRisk factors for community acquisition included: nrecent hospitalisation nprevious antibiotic therapy nresidence in a long-term care facility nintravenous drug use nColonisation and transmission are also seen in individuals (including children) lacking these risk factors Hiramatsu et al. Curr Opin Infect Dis 2002;15:407413 Layton et al. Infect Control Hosp Epidemiol 1995;16:1217; Naimi et al. 2003;290:29762984 Antimicrobial features of MRSA (1) nMechanism involves altered target site nnew penicillin-binding protein PBP 2 (PBP 2a) nencoded by chromosomally located mecA gene nConfers resistance to all -lactams nGene carried on a mobile genetic element staphylococcal cassette chromosome mec (SCCmec) nLaboratory detection requires care nNot all mecA-positive clones are resistant to methicillin Hiramatsu et al. Trends Microbiol 2001;9:486493 Berger-Bachi 178:165171 Antimicrobial features of MRSA (2) nCross-resistance common with many other antibiotics nCiprofloxacin resistance is a worldwide problem in MRSA: ninvolves 2 resistance mutations nusually involves parC and gyrA genes nrenders organism highly resistant to ciprofloxacin, with cross-resistance to other quinolones nIntermediate resistance to glycopeptides first reported in 1997 Hiramatsu et al. J Antimicrob Chemother 1997;40:135136 Hooper. Lancet Infect Dis 2002;2:530538 Clinical features of MRSA nCommon associations include: nunderlying chronic disease, especially repeated hospital stays nprolonged/repeated antibiotics, especially the -lactams nUsually susceptible to at least one other antibiotic nNot all MRSAs behave as EMRSAs nMethicillin resistance is not a marker of virulence Clinical features of MRSA: transmission nOccurs primarily from colonised or infected patients via the hands of healthcare workers ncontact transmission to other patients or staff very common nAirborne transmission important in the acquisition of nasal carriage nInfection control measures include: nscreening and isolation of new patients suspected of carrying MRSA or S. aureus with vancomycin resistance nimplementing infection control programmes nestablishing adequate antibiotic policy to minimise development of resistance Management of MRSA EducateEducate on risks and control measures on risks and control measures Adhere Adhere to strict control measures to prevent to strict control measures to prevent transmission, especially through contacttransmission, especially through contact TreatTreat patient with appropriate empiric patient with appropriate empiric andand targeted therapy targeted therapy Consider Consider clearing patient of MRSA carriageclearing patient of MRSA carriage Glycopeptide resistance: focus on vancomycin resistance nVancomycin-resistant enterococci (VRE) nVancomycin-resistant S. aureus (VRSA) Features of quinolone resistance: Gram-negative organisms nResistance most common in organisms associated with nosocomial infections nPseudomonas aeruginosa nAcinetobacter spp. nalso increasing among ESBL-producing strains nMeropenem Yearly Susceptibility Test Information Collection (MYSTIC) surveillance programme (19972000) n13.4% of Gram-negative strains resistant to ciprofloxacin nP. aeruginosa and Acinetobacter baumannii are the most prevalent resistant strains nincreasing prevalence of resistance during surveillance period Masterton. J Antimicrob Chemother 2002;49:218220 Thomson. J Antimicrob Chemother 1999;43(Suppl. A):3140 Gram-negative organisms with resistance to ciprofloxacin (1997 SENTRY data) Organisms (%) 0 30 50 10 Stenotrophomonas maltophilia 20 40 Acinetobacter spp.P. aeruginosaEscherichia coli All patients (USA) Lower RTI (USA and Canada) Organism type Jones. Chest 2001;119:397S404S Features of quinolone resistance: Gram-positive organisms nMRSA nS. aureus occurred in 22.9% of pneumonias in hospitalised patients in USA and Canada (1997 SENTRY data) nEnterococcus spp. resistanc