Microbiology and Infection Control A topic that Bugs us Both

1. Microbiology and Infection ControlA topic that Bugs us Both Bruce Gamage, RN BSN BSc CIC BC Centre for Disease Control

2. Outline • Definitions • Nosocomial Infections • Routine Practices and Transmission-Based Precautions • Antibiotic Resistant Organisms • Microbiology Laboratory and Infection Control

3. Definitions • Colonization: Presence of microorganisms in or on a host with growth and multiplication but without tissue/cell invasion and inflammation. • Infection:The entry and multiplication of a infectious agent in the tissues/cells of a host.

4. Definitions • Inflammation:The succession of changes that occur in living tissue when it is injured. • Symptoms are: Pain (dolar), heat (calor), redness (rubor), swelling (tumor), impaired function, general feeling of discomfort.

5. Definitions • Nosocomial infection:An infection that was not present or incubating at the time of admission to the facility. The infection becomes apparent 72 hours after admission. • Community infection:An infection apparent at the time of admission or during the first 72 hours of admission.

6. Definitions • Normal flora: Consists of relatively fixed types of microorganisms regularly found in a given area and when washed promptly reestablish themselves. • Transient flora:Consists of microorganisms that inhabit the skin or mucous membranes for hours, days, or weeks, derived from the environment, generally does not produce disease and does not establish itself permanently on the host. Transient flora may colonize, proliferate and produce disease.

7. Chain of Infection Causative agent Portal of entry Reservoir Susceptible host Portal of exit Mode of transmission When the chain of infection is broken the infectious process is halted.

8. Nosocomial Infections • Risk Factors • Steroids, chemotherapy, Antibiotics • Invasive devices, procedures • Virulence of pathogens • Prolonged hospital stay

9. Routine Practices • Routine infection control practices are the minimum level of precautions that should be used with all patients, at all times, regardless of presumed infectious status.

10. Hand Washing/Hand Antisepsis • Hands must be cleaned: • After any direct contact with a patient, before contact with the next patient • Before performing invasive procedures • After contact with blood, body fluids, secretions and excretions and exudates from wounds • After contact with items known or likely to be contaminated • Immediately after removing gloves

11. Alcohol-based hand antiseptics • Alcohol-based hand antiseptics are superior to soap and water in reducing hand contamination and should be made available as an alternative to hand washing

12. Gloves • Gloves should be used as an additional measure, not as a substitute for hand washing • Not required for routine patient care activities in which contact is limited to a patient's intact skin • For contact with blood, body fluids, secretions and excretions, mucous membranes, draining wounds or non-intact skin.

13. Masks and Eye Protection • Masks and eye protection or face shields should be worn: • To protect the mucous membranes of the eyes, nose and mouth • During procedures likely to generate splashes or sprays of blood, body fluids, secretions or excretions.

14. Mask vs. Respirator • A fluid resistant surgical or procedural mask should be worn to protect mucous membranes from splashes of body fluids

15. Mask vs. Respirator • If protection is required from airborne or aerosolized pathogens then a NIOSH or equivalent approved, N95 respirator must be worn

16. Gowns • Gowns should be used to: • Protect uncovered skin and • Prevent soiling of clothing • During procedures and patient care activities likely to generate splashes or sprays of blood, body fluids, secretions, or excretions

17. Sharps Safety • Handle sharps/equipment safely • Sharp items should be placed immediately in puncture-resistant containers located in the area where the items were used.

18. Transmission-based Precautions • Airborne Precautions • Droplet Precautions • Contact Precautions

20. Transmission Routes and Precautions

21. Antimicrobial-Resistant Organism Definition: “An organism that is resistant to two or more unrelated antibiotics to which the organism is normally considered susceptible.” • Bennett and Brachman, 4th edition.

22. Emergence of AROs

23. Factors That Promote Resistance • Resistance genes are prevalent in nature • Rapid multiplication of organisms favors genetic mutations • Selective pressure from antimicrobial use in humans and animals allows resistant organisms to predominate • Biofilms?

25. MRSA: Epidemiology • In the US MRSA is endemic in majority of hospitals (36% of all S. aureus isolates) • In Canada (CNISP) • 1995 0.9% of S. aureus isolates and 0.3 cases per 1000 admissions • 1999 6% of S. aureus isolates and 4.12 cases per 1000 admissions

26. BCCAMM Surveillance Project

27. World-Wide Prevalence of MRSA UK (42%) Denmark (<1%) Europe (24%) Canada (6%) Japan (74%) USA (36%) China (39%) Hong Kong (80%) Latin America (29%) Australia (30%) South Africa (49%) India (34%)

28. VRE: Epidemiology • In US: 1995 > 10% of enterococcal strains VRE • In Canada: • First VRE reported in 1993 • 411 cases reported in 23 hospitals between October 1998-September 2000 • 95% are colonization picked up on screening

29. BCCAMM Surveillance Project

30. VISA and VRSA • VISA first recognized in 1996 in Japan • Additional cases reported from Europe, Asia, and the US • Resistance has not been caused by the vanA, vanB, or vanC genes • VRSA seen in US in 2002 • Resistance gene vanA was detected in the isolate • No detected transmission to others

31. Control of ARO • Screening Cultures • Contact Precautions • Environmental Disinfection • Antibiotic Controls • HCW/Public Education

32. Role of the Microbiology Laboratory • Organism ID and susceptibility • Monitor antibiotic resistant organisms • Notifying IC of significant findings • Outbreak Investigations • Strain typing • Reportable organisms

33. Typing Methods • Phenotypic – observable characteristic (genes and environment interacting) • Genotypic – genetic constitution – examination of DNA

34. Phenotypic Typing Methods • Widely available for several decades • May be quicker and more readily available (but not always) • Examples • Antibiotic resistance typing – many bacteria • Serotyping – eg Salmonella, Neisseria meningitidis

35. Antibiotic Resistance Typing(Antibiogram) MRSA (+ urease tube)

36. Serotyping • Well established method – often being superseded by genotyping • Antibodies to variable antigens (often cell wall or cell membrane) prepared and, with a choice of methods (e.g. latex agglutination, ELISA) used to assign an isolate to a group or type. • Still used for Salmonella ‘speciation’, also Legionella.

37. Genotypic Typing Methods • More recently developed and often more expensive • Less readily available (usually at reference lab) and slower even if ‘on site’ • Examples • PCR (ribotyping) • Restriction enzyme based typing e.g. Pulsed Field Gel Electrophoresis • Sequence based methods

38. PCR based Typing • Use PCR to produce multiple amplicons whose size distribution varies from strain to strainand which can be separated by gel electrophoresis • Can be used in Staph. aureus – initial investigation to show that isolates are not closely related or need further investigation (PFGE) • Relatively quick but quite difficult to standardize between laboratories

39. Pulsed Field Gel Electrophoresis • Extract DNA and cut with specific restriction enzyme to give characteristic pattern of fragment sizes • Choice of enzymes – large or small fragments • Small fragments – easier to separate but less standardized • Large fragments – need special equipment to separate (PFGE) • Still fairly slow (2-3 days) but standard for many organisms now • e.g. E .coli O157, Staphylococcus aureus

40. PFGE (MRSA)

41. Sequence-Based Typing • Automatable process (computer analysis necessary) • ‘Digital’ results - easier comparison between labs • More expensive (at present) • Can choose level of discrimination • Coarse – multiple stable genes – look at long term evolutionary trends • Finer – fewer, variable gene(s) - outbreak investigation / local surveillance

42. Reportable Diseases • List of diseases reportable by all sources/laboratories • http://www.bccdc.org/content.php?item=7 • Liason between IC and public health

44. Summary • Follow Routine Practices • Read the signs on the door • Work with infection control • Reportable diseases • Special thanks to: • Mary McNaughton RN, MSA, CIC • Jim Curtin RN, BScN, CIC

45. Resources • Health Canada: Routine practices and transmission- based precautions in health care http://www.hc-sc.gc.ca/pphb-dgspsp/publicat/ccdr-rmtc/99vol25/25s4/index.html • Mayhall, C.G. Hospital Epidemiology and Infection Control. 2nd Edition. Lippincott, Williams & Wilkins. 1999. • Pfeiffer, J. A. APIC Text of Infection Control and Epidemiology. Association for Professionals in Infection Control and Epidemiology. Inc. 2005.