Infection Control

1. Infection Control Friday 1/11/08

2. Spread of resistance Antibiotic pressure Human to human transmission

3. Modes of transmission of ID • Contact • Most important & frequent route of transmission for NI • Droplet • Droplets > 5m containing microorganisms • Airborne • Droplet nuclei <5 µm containing microorganisms • Common Vehicle • Transmitted by contaminated items • Other: • Fecal-Oral • Sexual • Vectorborne

4. Nosocomial vs. Community spread

5. Infection control - preventing transmission of pathogens (focus on resistant ones) • Surveillance • Barrier precautions (= standard + contact precautions) • Isolation / cohorting • Gown • Gloves • Hand washing/alcohol

6. The need for active surveillance (Harris et al.): • Undetected ratio = patients undetected by clinical cultures all patients colonized or infected • Higher ratio - more effective will active surveillance be (estimates: VRE ~90%, MRSA ~90%, GNR-MDR - lower).

7. Infection control - preventing transmission of pathogens (focus on resistant ones) • Surveillance • Barrier precautions (= standard + contact precautions) • Isolation / cohorting • Gown • Gloves • Hand washing/alcohol

8. Standard precautions • Wash hands with plain soap after touching blood, body fluids, excretions, or contaminated items whether or not gloves are worn. • Wear gloves when touching blood, body fluids, excretions, and contaminated items. • Put on clean gloves before touching non-intact skin or mucous membranes. • Change gloves between procedures on the same patient involving contact with high concentration of organisms. • Remove gloves and wash hands before touching the environment or other patients. • Wear mask and eye protection and gown during procedures causing splashes of blood or body fluid.

9. Contact precautionsAs standard precautions, plus: • Patient placed in single room or in a room with patients who have active infection with the same microorganism but no other infection (cohorting). • Wear gloves when entering the room. • Change gloves after contact with high concentration of microorganisms. • Remove gloves and wash hands with antiseptic agent when leaving patient’s environment. • Wear gown in the room if in contact with patient, environment, or if patient incontinent. • Remove gown before leaving room. • Avoid sharing of patient equipment.

10. Search & Destroy strategy • Selective screening of high risk groups • Defining high risk groups • Defining methods of screening • Subsequent isolation of colonized persons • Decolonization

11. S&D in highly endemic settings –is it feasible? • Bootsma et al – Math model – supports • Clancy et al. and Huang et al. – support Bootsma et al. PNAS 2006

12. Studies that test effectiveness of IC interventions • Descriptions of interventions to control outbreaks – defining a causal relation. • Quasi-experimental designs (before-after studies) • Randomized controlled intervention trials (None to date – why??) • Mathematical models

13. Klebsiela pneumoniae with carbapenemase in Israel(true story but hypothetical data)

14. Causal relationship • Cause precedes effect • Cause covary with effect • Alternative explanations for the causal relationship are implausible

15. Types of Quasi-experimental designs • Quasi-experimental designs without control groups • Quasi-experimental designs with control groups • Interrupted time-series designs (with/wo controls)

16. MRSA bacteremia / Huang et al. CID 2006

17. Screening is effective (MRSA infections in SICU) / Clancy et al. Infect cont & Hosp Epidemiol

18. Can IC interventions prevent antibiotic resistance??Quasi-experimental designs • What can we learn from them? • What are the limitation of these studies?