Epidemiology of Healthcare-Associated Infections

This content explores the epidemiology of healthcare-associated infections (HAIs), including factors influencing their occurrence, types of epidemiologic studies used, major types of HAIs, and epidemiologic factors related to the dynamic occurrence and distribution of these infections among patients. It also defines HAIs, their definition, and magnitude of the problem they pose in healthcare settings.

• Epidemiology
• Healthcare
• Infections
• HAIs
• Epidemiologic Studies

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1. Epidemiology of Healthcare- Associated Infections

2. Learning Objectives December 1, 2013 1. Describe the epidemiology of healthcare associated infections (HAI). 2. Summarise how agent, host and environmental factors affect the occurrence of HAIs. 3. Outline the types of epidemiologic studies that can be used in HAI epidemiology. 2

3. Time involved December 1, 2013 50 minutes 3

4. Healthcare -Associated Infections -1 December 1, 2013 Refer to infections associated with health care delivery in any setting hospitals long-term care facilities community and ambulatory settings home and community care 4

5. Healthcare -Associated Infections -2 December 1, 2013 Definition A localised or systemic infection that results from an adverse reaction to the presence of an infectious agent(s) or its toxin(s), for which there is no evidence of infection on admission to a health care facility An infection is frequently considered an HAI if it appears 48 hours after admission 5

6. Epidemiology December 1, 2013 Study of the dynamic occurrence, distribution, and determinants of health- related events in specified populations Defines the relationship of a disease to the population at risk Involves the determination, analysis, and interpretation of rates 6

7. Epidemiology of HAIs December 1, 2013 Explains occurrence of HAIs among patients and the magnitude of the problem Includes the distribution of HAIs by patient type causative pathogen unit of treatment period of time 7

8. Major Types of HAIs December 1, 2013 Catheter-associated urinary tract infection (CAUTI) Ventilator-associated pneumonia (VAP) Surgical site infection (SSI) Catheter related bloodstream infection (CR-BSI) 8

9. Epidemiologic Factors December 1, 2013 There are 3 main factors related to development of HAIs Host factors Agent factors Environmental factors 9

10. Host Factors December 1, 2013 Advanced age or premature birth severe burns and certain skin diseases Chronic obstructive pulmonary disease Immunodeficiency (due to drug, or irradiation) Coma HIV infection Malignancies Diabetes mellitus Severe malnutrition Circulatory impairment Open wound or trauma Bronchopulmonary disease 10

11. Agent Factors December 1, 2013 An infectious agent can be bacteria, virus, fungus, or parasite The majority of HAIs are caused by bacteria or viruses Two major types of bacteria that cause HAIs Gram-positive cocci (e.g., Staphylococci and Streptococci) Gram-negative bacilli (e.g., Acinetobacter, Pseudomonas, Klebsiella) 11

12. Environment Factors December 1, 2013 Extrinsic factors that affect either the infectious agent or a person s risk of exposure to that agent Include both the animate and inanimate environment of patients 12

13. Chain of Infection -1 December 1, 2013 Infectious agent Host Reservoir Portal of exit Portal of entry 13 Mode of transmission

14. Chain of Infection -2 Infection results from an interaction between an infectious agent and susceptible host The interaction occurs by means of contact between the agent and the host and is affected by the environment Breaking the chain of infection by interrupting transmission generally the best way to prevent HAIs December 1, 2013 14

15. Infectious Agents December 1, 2013 A pathogen that causes an HAI Most important pathogens causing HAI are Gram-negative bacteria 15

16. Reservoir December 1, 2013 Definition: Place in which an infectious agent can survive but may or may not multiply Common reservoirs: humans animals equipment/fomites 16

17. Human Reservoirs December 1, 2013 Human reservoir: Persons with acute or subclinical illness Carriers convalescent carriers chronic carriers intermittent carriers 17

18. Portal of Exit December 1, 2013 The path by which an infectious agent leaves the reservoir Respiratory tract Genitourinary tract Gastrointestinal tract Skin/mucous membrane Blood Transplacental 18

19. Modes of Transmission December 1, 2013 A pathogen may be transmitted by a single route or it can be transmitted in several ways Modes of transmission are as follows: Contact transmission: direct, indirect-contact, and droplet Airborne transmission Vehicle transmission Vector-borne transmission 19

20. Contact Transmission December 1, 2013 Direct contact person-to-person spread, actual physical contact Indirect contact contact with contaminated intermediate object 20

21. Droplet Transmission December 1, 2013 Large droplets generated by an infected or colonised person during coughing, sneezing, talking, suctioning, etc. Droplets propelled a short distance <3m Droplets deposited on a susceptible host s eyes, nasal mucosa or mouth 21

22. Airborne Transmission December 1, 2013 TB or not TB? Droplet nuclei, dust particles or skin squames containing microorganisms are transmitted to a susceptible host by air currents 22

23. Common Vehicle Transmission December 1, 2013 Microorganisms are transmitted to susceptible hosts from common items: Food Water Medications Devices/equipment 23

24. Vector-borne Transmission December 1, 2013 Transfer of microorganisms by insects, flies, rats, or other vermin Uncommon mode of transmission in hospitals 24

25. Portal of Entry December 1, 2013 The path by which an infectious agent enters the susceptible host Respiratory tract GU tract GI tract Skin/mucous membrane Parenteral Transplacental 25

26. Susceptible Host December 1, 2013 A person lacking effective resistance to a particular microorganism 26

27. HAI Surveillance December 1, 2013 Systematic, active, on-going observation of the occurrence and distribution of HAIs and of the events or conditions that increase the risk of HAI occurrence Information that allows facility to direct efforts toward the most serious HAI problems and risks, to obtain support of personnel, and to provide feedback on the results of preventive changes 27

28. Use of Surveillance Information December 1, 2013 Provide baseline information on HAI occurrence Identify epidemics Evaluate efficacy of HAI preventive measures Reinforce appropriate infection prevention and patient-care practices Defend against malpractice suits Provide data for comparisons, problem solving and/or research Plan and measure the impact of implementing recommendations 28

29. Types of Studies December 1, 2013 Epidemiological studies can be classified as either observational or experimental The most commonly used types of epidemiological studies are: Descriptive study Analytic study Experimental study 29

30. Descriptive Study December 1, 2013 Describes the occurrence of a disease in a population and is often the first step in an epidemiological investigation 30

31. Analytic Study December 1, 2013 Analyses and tests relationships between a disease and its causes Case-control studies are used to investigate causes of diseases, especially rare diseases The possible cause is compared between cases (people with a disease) and controls (people without a disease) 31

32. Cohort Study December 1, 2013 A group of people (a cohort) is evaluated, none of whom has experienced the outcome of interest People in the cohort are classified according to characteristics or exposures that might be related to the outcome Groups with and without certain exposures or characteristics are then observed over time to compare the outcome 32

33. Experimental Study December 1, 2013 Involves an active attempt to change a disease determinant, such as an exposure or behavior, or the progress of a disease, through treatment, usually involving a randomized controlled trial with patients as subjects Field trials and community trials are other experimental designs in which the participants are healthy people and communities, respectively 33

34. Type of epidemiological studies Type of study Alternative name December 1, 2013 Unit of study Observational studies Descriptive studies Analytical studies Ecological Correlational Population Cross-sectional Prevalence Individuals Case-control Case-reference Individuals Cohort Follow-up Individuals Experimental studies Intervention studies Patients Randomised controlled Clinical trials Patients trials Field trials Healthy people 34 Community trials Community intervention studies Communities

35. Summary -1 HAIs can cause serious complications and greatly impact patients, their families, and health care personnel Health care personnel need to understand the epidemiology of HAIs to prevent them in their own settings Understanding the chain of infection and epidemiology of HAIs can lead to effective prevention and control intervention December 1, 2013 35

36. Summary -2 December 1, 2013 The epidemiology of HAIs can explain what happens to whom, and where and when it happens i.e., the occurrence and distribution of HAIs Using evidence-based recommendations can reduce infection rates This information supports effective planning and implementation of programs to prevent HAIs 36

37. References December 1, 2013 Ostrowsky B. Epidemiology of Health care-Associated Infections. In: Bennett & Brachman s Hospital Infections. 5thedition. Wolters Kluwer Lippincott Williams & Wilkins, Philadelphia. 2007; 3-23. Doshi RK, Patel G, MacKay R, Wallach F. Health care- Associated Infections: Epidemiology, Prevention, and Therapy. Mount Sinai J Med 2009; 76: 84 94. Overview of Epidemiologic Study Designs. In: Essentials of Epidemiology in Public Health. Aschengrau, A, Seage, GR, eds. Jones and Bartlett, Sudbury MA. 2006; 135-162. 37

38. Web Resource December 1, 2013 Centers for Disease Control and Prevention Self-Study Course: Principles of Epidemiology in Public Health Practice, Third Edition The introductory self-study course is available online. The course provides an introduction to applied epidemiology and biostatistics; it consists of six lessons: Introduction to Epidemiology, Summarizing Data, Measures of Risk, Displaying Public Health Data, Public Health Surveillance, and Investigating an Outbreak. Continuing education credits are offered to physicians, nurses, veterinarians, pharmacists, certified public health educators, and other professionals. The textbook is available at no charge at http://www.cdc.gov/training/products/ss1000/ss1000-ol.pdf and the self-study course (SS1000) is available at no charge at http://www2a.cdc.gov/tceonline/registration/detailpage.asp?res_id =1394. 38

39. Quiz 1. Epidemiologic information can help the healthcare facility plan interventions to prevent HAIs. True/False? What is the most frequent and important mode of transmission of HAIs? Airborne Droplet Vectorborne Contact What type of retrospective design study is often used to investigate causes of HAIs, comparing people who have an HAI with people without an HAI. Correlational Case-control Prevalence Randomised clinical trial December 1, 2013 2. a. b. c. d. 3. a. b. c. d. 39

40. International Federation of Infection Control IFIC s mission is to facilitate international networking in order to improve the prevention and control of healthcare associated infections worldwide. It is an umbrella organisation of societies and associations of healthcare professionals in infection control and related fields across the globe . The goal of IFIC is to minimise the risk of infection within healthcare settings through development of a network of infection control organisations for communication, consensus building, education and sharing expertise. For more information go to http://theific.org/ December 1, 2013 40