Transcript Handwashing
Post PCR Detection/Confirmation – DNA Sequence Analysis – Heteroduplex Mobility Assay – Reverse Line Blot – ELOSA DNA Sequence Analysis • Gold Standard • Essentially Reading of Amplified Genetic Code Heteroduplex Mobility Assay Reverse Line Blot Liquid Hybridization/ELOSA • LH-Like Fluorescent Hybridization Assays, but typically Chemiluminescent • ELOSA-Like ELIZA only using Oligonucleotides rather than Antibodies Molecular Typing Techniques – RFLP/AFLP – AP/RAPD PCR – TRFLP RFLP AFLP RAPD-PCR TRFLP Proteomic Techniques • MALDI-TOF MS • SELDI-TOF MS MALDI-TOF MS SELDI-TOF MS Quantitation Considered • Endpoint Dilution • Quantal Assay/MPN • Discrete Enumeration • Fluorescent Detection End-Point Dilution • Serial dilution (typically 10-fold) • Presence/Absence or Discrete Enumeration • Can be applied to most methods • Robust, but subject to pipetting errors Quantal Assay/MPN • Score each sample as +/• Statistical estimation of titer • Accuracy/Precision improves with increased replication • Large confidence intervals Discrete Enumeration • Direct count of Colonies/Plaques • Accuracy/precision improves with replication • Limited by concentration in counted dilution Fluorescent Detection • • • • Based on light emittance Luminometer Uses standard curves Indirect method (one more step to be inhibited) Antisepsis/Hand Hygiene Definitions • Hand hygiene – Performing handwashing, antiseptic handwash, alcoholbased handrub, surgical hand hygiene/antisepsis • Handwashing – Washing hands with plain soap and water • Antiseptic handwash – Washing hands with water and soap or other detergents containing an antiseptic agent • Alcohol-based handrub – Rubbing hands with an alcohol-containing preparation • Surgical hand hygiene/antisepsis – Handwashing or using an alcohol-based handrub before operations by surgical personnel Guideline for Hand Hygiene in Health-care Settings. MMWR 2002; vol. 51, no. RR-16. Preparations for hand Hygiene • Plain soap (detergent-based containing esterified fatty acids and NaOH or KOH) • Alcohols (isopropanol, n-propanol, ethanol or combo) – 60-95% alcohol most effective (70% w/w ideal) – Mechanism is denaturing of proteins, proteins not denatured as easily in absence of water • Chlorhexidine (chlorhexidine gluconate) – Mechanism is attachment and disruption of cytoplasmic membrane resulting in precipitation of cellular contents • Chloroxylenol (PCMX, halogenated phenolic) – Mechanism is inactivation of bacterial enzymes and alteration of cell walls Preparations for hand Hygiene • Hexachlorophene (bisphenol compound) – Mechanism is inactivation of essential enzyme activity in microbes • Iodine and Iodofors – Mechanism is impaired protein synthesis and alteration of cell membranes • QACs (quaternary ammonium compounds) – Mechanism is binding to cytoplasmic membrane causing leakage of low MW constituents • Triclosan – Mechanism is interference with synthesis of RNA, fatty acids, and proteins So Why All the Fuss About Hand Hygiene? Most common mode of transmission of pathogens is via hands! Infections acquired in healthcare Spread of antimicrobial resistance Hand Hygiene: The Data Since 1977, 7 of 8 prospective studies have shown that improvement in hand hygiene significantly decreases infection rates Clin Infect Dis 1999;29:1287-94 Historical Perspective • As early as 1822, a french pharmacist Labbarraque reported on the use of chlorides of lime or soda for cleansing hands • In 1842 Holmes concluded puerperal fever spread by hands of health care workers • In 1846, Semmelweis observed that women who had babies delivered by doctors coming from autopsies had a higher mortality rate than women whose babies were delivered by midwives, postulated puerperal fever caused by cadavarous particles • In 1847 he insisted physicians and students clean their hands with a chlorine solution, mortality rates dropped, first evidence disinfection more effective than soap and water alone Ignaz Semmelweis, 1815-1865 – First Clinic: Doctors and medical students – Second Clinic: Midwives 16 Maternal mortality, 1842 • 1840’s: General Hospital of Vienna • Divided into two clinics, alternating admissions every 24 hours: 14 12 10 8 6 4 2 0 First Clinic Second Clinic The Intervention: Hand scrub with chlorinated lime solution Hand hygiene basin at the Lying-In Women’s Hospital in Vienna, 1847. Hand Hygiene: Not a New Concept Maternal Mortality due to Postpartum Infection General Hospital, Vienna, Austria, 1841-1850 Semmelweis’ Hand Hygiene Intervention Maternal Mortality (%) 18 16 14 12 10 8 6 4 2 0 1841 1842 1843 1844 1845 MDs 1946 1847 1848 1849 1850 Midwives ~ Hand antisepsis reduces the frequency of patient infections ~ Adapted from: Hosp Epidemiol Infect Control, 2nd Edition, 1999. Modern History • 1961 US Public Health Service produced training film for Health Care Workers (HCW) recommending 1-2 minute hand scrub with soap and water • 1975 and 1985 formal handwashing guidelines published by CDC recommended washing with soap and water between majority of patients and with antimicrobial soap after invasive procedure • 1988 and 1995 guidelines for hand washing and antisepsis published by APIC, similar to CDC but 1995 document gave consideration to alcohol hand rubs • 1996 HICPAC recommended antimicrobial soap or waterless antiseptic agent be used upon leaving rooms of patients infected with drug resistant organisms • Though adopted by majority of hospitals, adherence by HCWs still low Current Recommendations • Joint task force HICPAC/APIC/SHEA/IDSA • When hands visibly soiled use soap and water, if not visibly soiled use alcohol based rub or wash with soap and water • Decontaminate hands with alcohol rub Before: – Direct contact w/patients – Gloving – When moving from contaminated body area to clean area After: – Contact with patient – Contact with inanimate objects – Removing gloves • Wash with soap and water before eating or after using restroom Recommended Hand Hygiene Technique • Handrubs – Apply to palm of one hand, rub hands together covering all surfaces until dry – Volume: based on manufacturer • Handwashing – Wet hands with water, apply soap, rub hands together for at least 15 seconds – Rinse and dry with disposable towel – Use towel to turn off faucet Guideline for Hand Hygiene in Health-care Settings. MMWR 2002; vol. 51, no. RR-16. Hand Hygiene Practices in Healthcare • Hand hygiene has been reported to average 40% (34 studies) – Inaccessibility of hand hygiene supplies – Skin irritation from hand hygiene agents – Inadequate time for hand hygiene – Interference with patient care – Lack of knowledge of the guidelines – Lack of information on the importance of hand hygiene Hand Hygiene Adherence in Hospitals Year of Study Adherence Rate Hospital Area 1994 (1) 29% General and ICU 1995 (2) 41% General 1996 (3) 41% ICU 1998 (4) 30% General 2000 (5) 48% General 1. Gould D, J Hosp Infect 1994;28:15-30. 2. Larson E, J Hosp Infect 1995;30:88106. 3. Slaughter S, Ann Intern Med 1996;3:360-365. 4. Watanakunakorn C, Infect Control Hosp Epidemiol 1998;19:858-860. 5. Pittet D, Lancet 2000:356;1307-1312. Hand Hygiene Practices in Healthcare • Observational studies revealed that duration averages from 6.6 to 21 sec, and in 10/14 studies HW <15 sec, and in 8/14 studies HW < 10 sec • HCWs also fail to wash all surfaces of their hands and fingers effectively Areas Most Frequently Missed HAHS © 1999 Many personnel don’t realize when they have germs on their hands Nurses, doctors and other healthcare workers can get 100s or 1000s of bacteria on their hands by doing simple tasks, like •pulling patients up in bed •taking a blood pressure or pulse •touching a patient’s hand •rolling patients over in bed •touching the patient’s gown or bed sheets •touching equipment like bedside rails, over-bed tables, IV pumps How can this happen? Culture plate showing growth of bacteria 24 hours after a nurse placed her hand on the plate Hand Hygiene and “Clean Procedures” • Personnel contaminate hands by performing “clean procedures” • Nurses contaminate hands with 100-1000 CFU during such “clean” activities as lifting patients, taking the patient’s pulse, blood pressure, or oral temperature, or touching the patient’s hand, shoulder, or groin. Colonized or Infected: What is the Difference? • People who carry bacteria without evidence of infection (fever, increased white blood cell count) are colonized • If an infection develops, it is usually from bacteria that colonize patients • Bacteria that colonize patients can be transmitted from one patient to another by the hands of healthcare workers ~ Bacteria can be transmitted even if the patient is not infected ~ The Iceberg Effect Infected Colonized Recovery of VRE from Hands and Environmental Surfaces Up to 41% of healthcare worker’s hands sampled (after patient care and before hand hygiene) were positive for VRE1 VRE were recovered from a number of environmental surfaces in patient rooms VRE survived on a countertop for up to 7 days2 1 Hayden MK, Clin Infect Diseases 2000;31:1058-1065. 2 Noskin G, Infect Control and Hosp Epidemi 1995;16:577-581. The Inanimate Environment Can Facilitate Transmission X represents VRE culture positive sites ~ Contaminated surfaces increase cross-transmission ~ Abstract: The Risk of Hand and Glove Contamination after Contact with a VRE (+) Patient Environment. Hayden M, ICAAC, 2001, Chicago, IL. Hand hygiene and ID risk in Community Setting • Meta Analysis of 30 studies published from 1960-2007. • Reduction in gastrointestinal illness 31% (95% CIs: 19% and 42%) • Reduction in respiratory illness 21% (95% CIs: 5% and 34%) – No difference between plain and antibacterial soap ~40% GI, 50% RI – Alcohol handrubs - 26% – Benzalkonium chloride hand sanitizer - 41% Aiello et al., AJPH 98(8):1372-1381, 2008 Efficacy of Hand Hygiene Preparations in Killing Bacteria Good Better Plain Soap Antimicrobial soap Best Alcohol-based handrub Studies Comparing Relative Efficacy of Plain Soap or Antimicrobial Soap vs Alcohol-Based Antiseptics in Reducing Counts on Hands • Alcohol more effective than plain soap (17 studies) • In all but two trials (15/17), alcohol-based solutions reduced bacterial counts on hands to a greater extent than washing with soaps or detergents containing povidone-iodine, 4% CHG, or triclosan Bacterial Reduction Ability of Hand Hygiene Agents to Reduce Bacteria on Hands % 99.9 Time After Disinfection log 0 60 180 minutes 3.0 99.0 2.0 90.0 1.0 0.0 0.0 Alcohol-based handrub (70% Isopropanol) Antimicrobial soap (4% Chlorhexidine) Baseline Plain soap Adapted from: Hosp Epidemiol Infect Control, 2nd Edition, 1999. Alcohol-Based Hand Cleansers Soap and Water Alcohol Solution # of HCWs n = 43 n = 43 Reduction in CFUs 50% 88% Non-medicated soap used; alcohol was mixture of n-propanol and isopropanol; hands contaminated under clinical conditions Am J Infect Control 1999; 27:258-61 Skin Prep • Chlorhexidine 2% is more effective than povidone iodine (Betadine) because it dries quickly and has longer residual action • If you must use Betadine – Allow Betadine to dry completely (at least 2 minutes) – Do not blow on, fan, or blot the site to make it dry faster!