Hospital Epidemiology And The Laboratory - PDF

Hospital Epidemiology and the Laboratory JEANMARIE MAYER, MD CHIEF MEDICAL EPIDEMIOLOGIST UNIVERSITY OF UTAH HEALTH CARE  Objectives Ø Discuss burden of healthcare associated infections (HAIs) in the U.S. Ø List the common bacteria that cause HAIs Ø Describe st...

Hospital Epidemiology and the Laboratory JEANMARIE MAYER, MD CHIEF MEDICAL EPIDEMIOLOGIST UNIVERSITY OF UTAH HEALTH CARE  Objectives Ø Discuss burden of healthcare associated infections (HAIs) in the U.S. Ø List the common bacteria that cause HAIs Ø Describe steps in an outbreak investigation Ø Discuss how the laboratory can be helpful in an outbreak  Definitions…. Healthcare Associated Infections ◦ Acquired while receiving healthcare (e.g.; hospital, long term care facility) Colonization ◦ Organisms on a body surface (e.g.; skin, nose) without disease ◦ Example: MRSA nasal carriage Infection ◦ Organisms invade body tissues causing disease (clinical signs & symptoms) ◦ Example: MRSA blood stream infection Burden of HAIs  Monitoring HAIs in the U.S. o CDC’s National Healthcare Safety Network (NHSN) system o NHSN surveillance criteria ≠ clinical diagnosis! o NHSN reports are used to o Comply with state & federal reporting mandates o Benchmark o Drive progress to eliminate HAIs  HAIs at U.S. Hospitals HAIs occur in ~3% of admissions to U.S. hospitals during 2015* Hospitals are mandated to report some HAIs to CDC/NHSN: o Central Line Associated Bloodstream Infections CLABSI o Catheter Associated Urinary Tract Infections CAUTI o MRSA bacteremia o Surgical Site Infections of colon and hysterectomies SSI o Clostridioides difficile Infection CDI *N Engl J Med 2018; 379:1732-1744 DOI: 10.1056/NEJMoa1801550  It’s not just about the numbers…. Your father has open heart surgery Surgery goes well but he later dies of a MRSA wound infection that developed after surgery From Guh, CDC presentation: “Trends and Strategies for Prevention of HAIs”  Organisms causing HAIs Endogenous vs. exogenous sources o From the patient’s own microbiome o From the health care environment (i.e.; hands of providers/staff) Multi-Drug Resistant Organisms (MDRO) o Select for with antibiotic exposure o “Shared” via cross-transmission Leading Organisms causing HAIs in U.S. Hospitals 1. C. difficile 2. Staphylococcus aureus 3. Escherichia coli 4. Candida spp. 5. Enterococcus spp. 6. Enterobacter spp. 7. Pseudomonas aeruginosa 8. Klebsiella spp. 9. Streptococcus spp. 10. Coagulase negative staphylococcus N Engl J Med 2018; 379:1732-1744 DOI: 10.1056/NEJMoa1801550  Antibiotic Resistance Threats in the U.S. o Carbapenem-resistant Acinetobacter baumannii CRAB o Carbapenem-resistant Enterobacterales CRE o Candida auris o Clostridioides difficile https://www.cdc.gov/drugresistance/pdf/threats-report/2019-ar-threats-report-508.pdf Acquisition and Prevention of HAIs The Iceberg Effect Infected Colonized World Health Organization: 5 Moments for Hand Hygiene  Standard Body Substance Precautions With all patient contact ◦ HAND HYGIENE And more if anticipate exposure to body fluids ◦ Gloves, gown, mask, eye protection as needed ◦ Examples: ◦ Venipuncture: gloves ◦ Diarrhea: gloves, gown Transmission: Direct and indirect contact MRSA VRE CRE / CRAB C. difficile C. auris Also: Norovirus, RSV… Transmission: Droplets, Splashes Neisseria meningitidis Pertussis Group A strep H. influenza Influenza….. Transmission: Airborne Tuberculosis Chicken Pox Measles N95 respirator Limited airborne - SARS-CoV-2 PAPR: Powered Air Purifying Respirator Outbreak Investigations  Definitions…. Outbreak: ◦ “More cases of disease than expected in a given area or among a specific group of people over a period of time” HAI rates within a healthcare setting: ◦ Endemic ◦ “Predicted” number of cases ◦ Most nosocomial infections (? ~1/3 are preventable) ◦ Epidemic (Outbreak) ◦ Significant increase from endemic rate or unusual infection ◦ 100% preventable! Analyzing Variation with Control Charts Plots data over time o vs. aggregate pre/post Control limits describe variability Special cause variation o 1 value outside control limits o 8 consecutive values on one side of mean  Goals of an Outbreak Investigation Identify the: ◦ Etiologic agent ◦ Reservoir ◦ Mode of transmission Eliminate the reservoir Prevent transmission Prevent future outbreaks John Snow and the Broad Street Pump  Outbreak Investigation Steps o Verify diagnosis o Confirm outbreak o Research the disease o Case definition o Descriptive epidemiology o Develop a hypothesis o Test & refine the hypothesis o Implement control & prevention measures o Communicate findings Verify the Diagnosis & Confirm an Outbreak Implicit Assumptions oNo changes in: o case definition o method for diagnosis o Issues if o new test (e.g., PCR) o different case finding methods (e.g., active surveillance)  Pseudoepidemics oFalse clusters of real infections oReal clusters of false infections oPseudoepidemics o11% of 181 CDC nosocomial epidemic investigations 1956-75 due to: o errors collecting, handling, or processing specimens (55%) o surveillance artifacts (30%) o error of clinical diagnosis (15%)  EIA toxin pos/10,000 pt dys 0 20 40 60 80 100 120 2002-01 2002-03 2002-05 2002-07 2002-09 2002-11 2003-01 2003-03 2003-05 2003-07 2003-09 EIA Toxin Rate 2003-11 ICD9 Code Rate 2004-01 2004-03 2004-05 2004-07 2004-09 2004-11 2005-01 2005-03 2005-05 2005-07 2005-09 2005-11 2006-01 2006-03 2006-05 2006-07 2006-09 2006-11 2007-01 2007-03 2007-05 So, what did we do to control the “outbreak”? 2007-07 2007-09 2007-11 0 20 40 60 80 100 120 Lab & Administrative CDI Rates at U Health ICD9 code/10,000 pt dys Increased when a virulent strain was noted to cause increased rates elsewhere  Increasing CDI Rates: Date Investigation/Intervention Sep 05 Ongoing education and dissemination of CDI rates Oct 05- EVS cleaning from quat to chlorine releasing agent Mar 06 Reinforced infection control practices Apr 06 Maps to identify “hot spots” of HAI CDI acquisition Sep 06 Random chart reviews of CDI patients found inconsistent clinical symptoms Oct 06 Hospital wide gloving campaign at onset of ANY diarrhea Encouraged MDs to order C difficile cultures for typing Dec 06 Calculated hazard ratios for roommates, neighbors, and subsequent occupants of CDI cases Apr 07 No increased risk for CDI cases vs. controls with selected antibiotics Questioned lab re: EIA with poor recovery of C difficile from tox pos cases o Lab investigated QC o Observed random false pos for specimens in Cary Blair transport media May 07 Lab initiated policy to reject specimens collected in transport media Jun 07 20 isolates collected over 17 months (2/06 - 6/07) typed by REA Pseudoepidemic due to false positive lab tests Pct of patients pos (% ) No. unique pts tested 100 90 90 80 No. unique patients tested 80 Pct of patients pos (%) 70 70 60 60 50 50 40 40 30 30 20 20 10 10 0 0 -9 -8 -7 -6 -5 -4 -3 -2 -1 2 1 0 +1 +2 +3 +4 +5 +6 +7 +8 +9 0 +11 2 -1 -1 -1 +1 +1 Day lab began to reject specimens collected in Cary-Blair Media  A Real Outbreak Pharmacy identified 3 patients with Carbapenem Resistant Acinetobacter baumannii(CRAB) o Verified micro with lab o Learned 2 other facilities also had patients with CRAB o The next week….3 more cases at the hospital… Outbreak Investigation Steps o Verify diagnosis o Confirm outbreak o Research the disease o Case definition  Literature Review o Non-fermenter coccobacillus typically not virulent o More often a pathogen in ICU patients o Pneumonia, bacteremia, UTIs o CRAB outbreaks in U.S. o Similar stains across facilities & cities likely due to shared patients, staff o Prolonged environmental contamination o Respiratory/patient equipment, wound care o Outbreaks last weeks to 48 months  Case definition o Clinical info about the disease o Characteristics about affected individuals o Info on location o Specify time of the outbreak Our case definition o Any patient growing CRAB o Pulled micro data over previous 2 years o Only 1 other CRAB 6 months earlier Outbreak Investigation Steps oVerify diagnosis oConfirm outbreak oResearch the disease oCase definition oDescriptive epidemiology Descriptive Epidemiology  Epidemic Curves Plot cases over time Provides clues as to the o Mode of transmission o Person to person o Common source Common source Person to person  No. of CRAB Cases 0 1 2 3 4 Ju n_ w 1 Ju n_ w 2 * Index case Ju n_ w 3 Ju n_ w 4 Ju l_ w * 1 Ju l_ w 2 Ju l_ w 3 Ju l_ w 4 Initial Epicurve Au g _w 1 ** Au g _w 2 Au g _w 3 Outbreak Investigation Steps o Verify diagnosis o Confirm outbreak o Research the disease o Case definition o Descriptive epidemiology o Develop a hypothesis o Test & refine the hypothesis  Develop a hypothesis Use data from the epicurve, line list, literature, etc. ASK QUESTIONS (and make observations) o Who? o What? o Where? o When? o How?  Multiple Hypotheses CRAB introduced by an out of state case Potential reservoirs: o Unrecognized cases / locations o Examples: Respiratory therapy and patient care equipment Modes of transmission: o Person to person o Healthcare worker hands, stethoscopes… o Common & sporadic point sources o Contamination from the environment  Test the Hypothesis o Case Control study to identify risks o Compare proportion of case vs. controls exposed to risk factors o Molecular testing Molecular typing of initial cases 6C 7C 10C 11C 9Z 4B 2A Outbreak Investigation Steps o Verify diagnosis o Confirm outbreak o Research the disease o Case definition o Descriptive epidemiology o Develop a hypothesis o Test & refine the hypothesis o Implement control & prevention measures o Communicate findings  * * * * * Epicurve Control Measures  What’s wrong here? (note, staged scenarios) Where have those Is that chart going gloves been? back to the rack?  CRAB Alerts o Electronic alerts to Infection Prevention o Page Nurse Supervisors of CRAB patients at transfer & readmission o Weekly surveillance cultures in ICUs with ongoing transmission Cleaning the Environment: Identify Roles and Responsibilities Healthcare environment Portable equipment  The Big Clean Traffic control  And…. CRAB cases seen elsewhere during the hospital outbreak  CRAB Transmission Across Facilities Poor communication Infection control in long term care facilities o Knowledge gaps o FEASIBILITY of implementing precautions Led to: o Standardized form to communicate about resistant organisms o Healthcare facilities advocated reporting of CRAB/CRE o Acute and long term care partnerships  Summary Ø HAIs are a significant problem in the U.S. Ø Bacteria causing HAIs can be from o patient - healthcare staff hands - healthcare environment Ø Hospital Epidemiology follows steps to investigate an outbreak Ø The lab plays a significant role in outbreak investigations o review clinical specimens - surveillance testing – molecular testing