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 precautions As 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?