Nosocomial Infections

1. Nosocomial Infections Patrick Kimmitt

2. Today we are going to cover… • The factors that contribute to nosocomial infections • Examples of nosocomial infections and the organisms which cause them • Control of nosocomial infections • Surveillance of nosocomial infections

3. Nosocomial infections • The word derives from the Greek nosokomeian, meaning hospital • These days the terms hospital acquired – and healthcare associated – are used • A very emotive subject with the public, driven by the press • Do hospitals really deserve to be blamed for all cases of hospital infection?

4. Nosocomial infections are… • Infections that are acquired in hospital (48 hours or more after admission) • Approx 7% of patients will suffer from an infection whilst in hospital – the risk increases with length of stay • A significant financial burden on NHS

5. Impact of nosocomial infections • Possibly up to100,000 infections per year in UK • A cause of ~5,000 deaths with nosocomial infections playing a role in ~15,000 others • Costs the NHS £1 billion – 9% of its in-patient budget • Cannot be eradicated but it’s thought they could be reduced by up to 30%

6. Impact of nosocomial infections • Longer stays in hospital – bed occupancy • Outbreaks leading to ward closures especially norovirus and C. difficile • Pain and anxiety for patients and families • Loss of earnings

7. Where is the money spent?

8. Best to be proactive rather than reactive!!

9. Why are we more likely to get an infection in hospital? Consider 4 important factors… • The host • The microbes • The environment • Treatment

10. The host 1 • People in hospital are already sick! • They may have poor general resistance to infection • Lack of immunity • Extremes of age • Immunocompromised (eg cancer chemotherapy)

11. The host 2 • Reduced immunity • Diabetes, severe burns • Poor local resistance • Poor blood supply to tissues • Surgery • Wounds, sutures • Medical devices • Catheters, prostheses, tubing etc

13. The microbes • Virtually any infection can be acquired in hospital • However a number of “usual suspects” predominate • What are they, where do they come from and why do they cause nosocomial infection?

14. Opportunistic infections • Nosocomial infections are often caused by opportunistic pathogens i.e. those which do not normally cause infection in healthy people • May be a reflection of reduced defences of host or access to sites not normally colonised by organisms • May be from normal flora or environment • Antibiotic resistance is a problem

15. Opportunistic pathogens • Pseudomonas aeruginosa • staphylococci • E. coli and other coliforms • streptococci and enterococci • Bacteroides fragilis • Candida albicans • Herpes simplex virus • Cytomegalovirus

16. Biofilms • Biofilms are microbial communities (cities) living attached to a solid support eg catheters/ other medical devices • Biofilms are involved in up to 60% of nosocomial infections • Antibiotics are less effective at killing bacteria when part of a biofilm

17. The Environment • There are many different sources of pathogens when in hospital • Our own normal flora (endogenous infection) • Infected patients • Movement of staff and visitors • Environment e.g. fungi, Legionella • Blood products (v. rare) • Surgical instruments eg vCJD (v. rare)

19. Treatment • There is continuous usage of antibiotics in hospitals especially in ICU • As a result there will be a natural selection for strains that are antibiotic resistant – infections are getting harder to treat • This has led to problems with multi-resistant bacteria e.g. MRSA, VRE, ESBLs • Antibiotic treatment can also lead to alterations in normal flora and allow pathogens cause infection eg C. difficile

20. Sites of HAIs

21. Bloodstream nosocomial infections • Coagulase-negative staphylococci • Enterococci • Fungi e.g Candida albicans • Staphylococcus aureus • E. coli and other coliforms • Pseudomonas aeruginosa • Acinetobacter baumannii with substantial antimicrobial resistance - Reported with increasing frequency

22. Urinary Tract Infections • E. coli and other coliforms • Candida albicans • Enterococcus • Staphylococcus • Pseudomonas

23. Surgical site infections • S. aureus • Pseudomonas aeruginosa • Coagulase-negative staphylococci • Enterococcus • Candida albicans • E. coli

24. Causes of death • Primary bloodstream infection • Pneumonia • Infection of surgical site

25. Staphylococcus aureus • A common coloniser of the skin and mucosa (e.g. the nose) it is a classic opportunist • Causes skin and wound infections as well as septicaemia, urinary tract infections and pneumonia • Most strains are sensitive to many antibiotics…some are not…

26. MRSA • Methicillin (Meticillin) Resistant Staphylococcus aureus • S aureus carried by 30% of us (nose/ skin) • MRSA is more difficult to treat compared to MSSA • Resistance due to mecA gene – encodes PBP2a, doesn’t react with Penicillins • Emerging Vancomycin resistance is a concern • The Biomedical Scientist Jan 2008 p39-41

27. MRSA bacteraemia

28. Epidemic MRSA (EMRSA) • Epidemic strains have acquired a selective advantage for transmission in hospital environments • EMRSA-1 was identified in S.E. England in 1984. • Subsequent surveys showed further 13 multi-hospital MRSA (EMRSA-2 to -14) • Mid-1990s: EMRSA-15 and -16 emerged and spread rapdily • Approx 60% of MRSA isolates in hospitals are EMRSA-15, and 35% EMRSA-16

29. Rapid MRSA screening • Current methods for screening for MRSA are based on culture and take 48 hours • PCR-based screening can generate a result in 2 hours! • mecA is carried on a transferable gene cassette called SCCmec – but also found in coagulase-negative staphylococci • PCR developed using primers for SCCmec and orfX on the S. aureus chromosome

30. PCR product SCC 3` end orfX mecA Use of SCCmec/orfX PCR MRSA No PCR product MSSA orfX No PCR product MR CN-Staph SCC 3` end mecA Cuny & Witte Clin Microbiol Infect (2005) 11:834-837

31. Vancomycin Resistant Enterococci

32. Extended spectrum β-Lactamases • ESBLs are enzymes responsible for resistance to 3rd generation Cephalosporin antibiotics such as Ceftazidime and Cefotaxime • Resistance is found in E. coli and other members of the Enterobacteriacae • Often cross-resistance with other antibiotics making treatment difficult – use carbapenems

34. Clostridium difficile • Causes antibiotic-associated diarrhoea and pseudomembranous colitis – life-threatening illnesses • Normally affects only the elderly, especially those on long-term broad-spectrum antibiotics • Produces two powerful toxins and is a spore-former– difficult to eradicate, resistant to alcohol • Reasons for the rapid increase in cases is still not known

36. Clostridium difficile • Nosocomial disease spread primarily by hands of staff and “outbreaks” are common • Patients generally respond to discontinuation of the inciting agent or therapy with metronidazole or vancomycin. Response is rapid but Mtz and Vanc may also alter normal flora and may allow disease to recur • Once the colon is injured it is more susceptible to re-infection. “Relapse” rates are up to approx 20% • Almost impossible, at present, to rid the environment of C. difficile spores • Some use 1000-10000ppm hypochlorite – highly caustic and damaging to surfaces. There may be rapid re-contamination of environment.

37. Nosocomial transmission of C. difficile • Contamination rates after contact with CDAD patients: • Physicians & medical Students 75% of the time • Dialysis Technicians 66% of the time • Nurses 56% of the time • Physiotherapists 50% of the time • Underside of fingernails 43% • Fingertips and Palms 37% • Underside of Rings 20% • C difficile spores remain in environment in 34-58% of sites after “detergent” cleaning • CDC 2005

38. Success story • Scunthorpe and Goole NHS trust looked at changing their antibiotic prescribing policy to reduce the incidence of C. difficile disease • Cost £12,000 extra to implement • Saved £280,000 in staffing, bed occupancy, treatment, use of isolation rooms and of course lives

39. Infection Control • Infections may derive from endogenous (auto-infection) or exogenous sources (cross-infection) • We need to consider the chain of infection and the transmission of an infectious agent

40. Transmission • Contact – most common • Direct (physical contact) • Indirect (via contaminated objects) • Airborne Transmission • Droplet respiratory secretions on surfaces • Inhalation of infectious particles • Blood-borne transmission (v. rare) • Food-borne (rare)

41. Pathogen Transmission Susceptible person Infection or colonisation The Cycle of Contagion

42. Pathogen X X Transmission Susceptible person X X Infection or colonisation The Cycle of Contagion Immunisation or prophylaxis Immunisation or prophylaxis Individual treatment Infection control hygiene

43. Role of infection control teams • Education and training • Development and dissemination of infection control policy • Monitoring and audit of hygiene • Clinical audit

44. Isolation & barrier precautions Decontamination of equipment Prudent use of antibiotics Hand washing Decontamination of environment

45. Isolation & barrier precautions Decontamination of equipment Prudent use of antibiotics Hand washing Decontamination of environment The 5 pillars of infection control

46. Cleanyourhands campaign • An initiative that was rolled out in 2004 • Increased procurement of alcohol rub in wards • Poster campaign • Evaluation of this published in BMJ May 3 2012

47. Tabloid sensationalism?

48. Government response… Hospital superbug must be halved Bloodstream infections with the hospital superbug MRSA must be halved in three years, the government has said. Health Secretary John Reid tasked NHS hospitals with achieving a year on year reduction up to and beyond March 2008.

49. Government meddling?? • By forcing targets on NHS trusts for reduction of MRSA numbers, has this led to an increase in infections with other “superbugs”? • Hand washing with alcohol-based antiseptics is fine for decontamination of MRSA but have no effect on spores of C. difficile - need to wash with soap and water • Include soap as well as alcohol rub on wards

50. Some progress • In recent years there has been a steady decline in cases and deaths caused by both MRSA and C. difficle • Is our infection control policy paying off?