Pathogens Important to Infection Prevention and Control

1. Pathogens Important to Infection Prevention and Control

2. Learning objectives • List special pathogens of interest to IP&C, and for each, describe the impact on the IP&C programme • Explain how antibiotic-resistant bacteria cause problems in healthcare • Outline preventive measures for a given special pathogen

3. Time involved • 90 minutes

4. Special pathogens • Everyday problem microorganisms for infection prevention and control include: • Mycobacterium tuberculosis • Clostridium difficile • Antibiotic resistant organisms • MRSA, VRE • Gram-negative multiply resistant organisms • Enterobacteria (Escherichia coli, Klebsiella pneumoniae) • Pseudomonas aeruginosa • Acinetobacter baumanii

5. Mycobacterium tuberculosis • Mycobacterium tuberculosis causes tuberculosis (TB) • TB affects 1/3 of the world’s population • 9.4 million new cases in 2008 • 1.8 million deaths in 2008 • Leading cause of death in people living with human immunodeficiency virus (HIV)

6. Transmission and pathogenesis of TB - 1 • Spread by the airborne routewhen someone with activedisease and positive sputum smear coughs, talks, sneezes, or spits • Bigger droplets spread up to 1 m, smaller spread by air • Bacteria inhaled into lungs • In lung tissue and lymph nodes the bacteria grow and reproduce • Can travel to any location in the body

7. Transmission and pathogenesis of TB- 2 • Latent TB – bacteria contained in the body • 10% of people with latent TB will develop active disease • Most commonly affected organ - Lungs • Untreated, a person with active disease can infect 10 to 15 people a year

8. Clinical forms • Pulmonary TB (active) • Cough with thick cloudy, sometimes bloody sputum • Tiredness • Appetite loss/unexplained weight loss • Night sweats • Fever/chills • Shortness of breath • Extra pulmonary TB • Signs and symptoms vary with site of infection • Other common sites include central nervous system, bones, joints, and genitourinary system

9. Risk Factors • Weakened immune system • Contact with someone with active TB • Caring for active TB patients • Living or working in crowded conditions with someone with active TB • e.g., prisons, nursing homes, homeless shelters • Poor access to healthcare • Alcohol or drug abuse • Travel to places where TB is endemic • Being born in a country where TB is endemic • Some medications for rheumatoid arthritis

10. Vaccination • BCG strain of Mycobacterium bovis is used as a vaccine • BCG is given to infants (best soon after birth) • Vaccination against TB does not protect against infection but only against severe forms of disease • Meningitis • Disseminated TB (miliary)

11. Diagnosis & Management • Chest x-ray • Sputum smear for acid fast bacilli • Tuberculin skin test (TST) • Can take up to 3 months for those newly exposed to develop positive test • May be falselypositive because of BCG vaccination • Interferon gamma release assays (IGRA) in vaccinated persons • Culture (can take up to six weeks) and sensitivity test

12. Management &Treatment Management of Exposure • Confirmation of positive infection • Medical evaluation to determine follow up Treatment of patients • Treatment for latent or active TB should follow World Health Organization recommendations • Incomplete treatment can cause resistance • Adherence to therapy is critical

13. IP&C Measures Engineering controls • Negative pressure rooms • High efficiency particulate air (HEPA) filtration system • Enhanced ventilation • Ultraviolet irradiation (only in empty room) • Sunlight exposure • Open window (last resort if no other options)

14. Negative presssure room HEPA filter Air flow Patient with active TB isolated in negative pressure room

15. IP&C Measures - 1 Administrative Controls • Identify patients with signs and symptoms of TB • Additional precautions for patients suspected to have active TB • Prompt treatment • Vaccination of healthcare personnel • Respiratory etiquette

16. IP&C Measures - 2 Personal Protective Equipment* • N-95 fit tested masks for healthcare workers • If not available, then surgical masks • Surgical masks for patients leaving their rooms * Typically used for pulmonary TB if the patient is expectorating or has an open lesion

17. Conclusion • Despite the high global impact of TB, it is treatable and preventable • Occupation exposures remain a significant risk for healthcare workers • IP&C measures are needed to decrease exposures to patients and healthcare workers

18. Clostridium difficile: Background • There is a global increase in Clostridium difficileinfections (CDI) and outbreaks over the past 10 years; however the illness is not a problem in all countries • CDI primarily occurs in those patients exposed to antibiotics in healthcare facilities

19. Pathology - 1 • A Gram-positive spore forming anaerobic bacillus • Widely distributed in the environment • In its vegetative state • Produces toxins • Can be killed by antibiotics • Spore form • Dormant • No toxin production • Resistant to antibiotics and disinfectants • Can persist for months in the environment

20. Pathology - 2 • Produces 2 toxins • Toxin A and Toxin B • Bind to intestinal epithelial cells causing inflammation and diarrhea • Toxins are cytotoxic and enteropathic • Alteration of the gut flora by antibiotics an important risk factor (decrease of normal gut flora)

21. Clinical Significance • Mild disease • Non-bloody diarrhoea, often mucoid and foul smelling, cramping, nausea, dehydration, low grade fever, leukocytosis • Severe disease • Colitis, watery diarrhoea, abdominal pain, fever, nausea, abdominal distension, pseudomembranes in the gut, toxic mega colon, death

22. New Strain • Increased incidence of B1/NAP1/027 strain • Causes severe disease • More resistant to standard therapy • More likely to relapse • Associated with higher mortality • 16x more toxin A; 23x more toxin B • Related to excessive use of certain drugs/antibiotics

23. Colonisation • Approximately 3-5% of healthy adults and 20 to 40% of hospitalised patients may be colonised • Colonised patients generally are not symptomatic • May be a potential reservoir for transmission • Evidence suggest spores on the skin of asymptomatic patients can contaminate the hands of the healthcare worker • No recommendations to treat carriers nor to perform admission screening

24. Transmission and Control Measures

25. Additional Control Measures • Discontinuation of all antibiotics in a symptomatic patient (except for CDI) • Facility-wide antibiotic control policies • Early notification of patients with diarrhoea to the IC team • Not recommended • Routine identification of carriers • Repeat testing post treatment for clearance

26. Antibiotic Resistant Microorganisms

27. Methicillin Resistant Staphylococcus aureus (MRSA)

28. Background • Staphylococcus aureusis a Gram-positive bacteria • 30% of people are permanently colonised • Nose • Pharynx • Perineum • Transient colonisation occurs, mainly on hands • Colonisation although harmless, increases the risk of infection and transmission

29. Clinical Significance of MRSA • First a problem in 1960s • Globally has reached epidemic proportions • Both community associated (CA) and healthcare associated (HA) strains of MRSA • Rates vary by • Country • Region • Individual healthcare facility

30. MRSA Transmission and Control Measures

31. VISA and VRSA • Vancomycinis drug of choice for treating MRSA infections • Staphylococcus aureus with decreased (intermediate) susceptibility to vancomycin = VISA • Staphylococcus aureuswith resistance genes Van A or Van B = VRSA • So far only few isolates in different parts of the world

32. Vancomycin Resistant Enterococcus (VRE)

33. Background • Enterococci are normal gut bacteria • May also be present in the oropharynx, vagina, or on skin • Causes serious bacterial infections • Wound infections • Urinary tract infections • Endocarditis • Sepsis • Often resistant to ampicillin (the drug of choice); infections then treated with glycopeptides

34. VRE Epidemiology • VRE is enterococcus that is resistant to the glycopeptidevancomycin • First isolated in the 1980’s • Spread globally causing asymptomatic colonization, infections, and outbreaks • The prevalence of VRE varies worldwide

35. Clinical Significance • Clinically relevant strains carry Van A or Van B resistance genes • Limited antibiotics to treat VRE infections • Transfer of resistance genes to other microorganisms such as MRSA is a great concern

36. VRE Transmission and Control Measures

37. Multi-Drug Resistant Gram- Negative Microorganisms (MDRGN)

38. MDRGN- 1 • The “Enterobacteriaceae” family of bacteria are a normal part of the gastrointestinal flora • The most frequent isolates are: • Escherichia coli • Klebsiellapneumoniae • Serratiamarcescens • Enterobacter species

39. Mechanisms of Resistance Escherichia coli and Klebsiellapneumoniaecan have extended spectrum beta-lactamase (ESBL) enzymes that cause resistance to beta-lactam antibiotics including: • Penicillins • Cephalosporins • Cephamycins • Monobactams

40. Epidemiology of ESBL strains • There are various types of ESBLs including • TEM • SHV • CTX-M • ESBLs were first detected in Europe in 1980s • Surveillance data from several surveillance systems indicate high rates of ESBLs in many parts of the world including USA, Canada, Europe, China, India and Latin America

41. Epidemiology of CRE • Carbapenem antibiotics are the treatment of choice for serious infections due to ESBL-producing bacteria • Carbapenem Resistant Enterobacteriaceae (CRE) has also been reported • Carbapenemases of importance include KPC, VIM, OXA and NDM-1 • CREs have been reported in many areas of the world and have also been associated with outbreaks

42. MDRGN- 2 • The following bacteria are present in aquatic environments • Acinetobacterbaumannii • Pseudomonas aeruginosa • Opportunistic pathogens in humans • A major cause of healthcare-associated infections • Septicemia • Ventilator-associated pneumonia • Urinary tract infections

43. MDR P.aeruginosa and MDR A.baumannii • These microorganisms have intrinsically lower susceptibility to antibiotics • Acquiring additional resistance genes (ESBL genes, other genes for resistance to betalactam antibiotics, resistance genes for aminoglycosides and fluoroquinolones) very often means that they are • susceptible only to carbapenems or • colistin or • resistant to all antibiotics (panresistant)

44. Clinical Significance • MDRGN (including ESBLs, CREs, MDR PA and MDR AB) pose a significant treatment challenge including • Increased length of stay • Increased mortality • Increased cost • Contributes to the global crisis of antimicrobial resistance • Control requires an aggressive world-wide strategy

45. MDRGN Transmission and Control Measures

46. Management of Pathogens in Low Resource Countries • IP&C measures vary based on institutional setting and available resources • Hand hygiene should be a routine part of patient care in all settings • Additional precautions may be considered depending on the pathogen, the institutional setting and outbreak circumstances

47. Conclusion • Antimicrobial resistance is a world-wide public health problem • Solutions require a multi-faceted approach • Improving behaviours is essential • Global awareness and surveillance is required • Implementation of appropriate IP&C practices and antimicrobial stewardship processes may be beneficial

48. Key Points • Tuberculosis and multi-drug resistant bacteria are important infection prevention and control issues • Many have developed resistance to antimicrobials making them less effective • Control measures vary by organism, setting and resources

49. Further reading • Apisarnthanarak A, Fraser VJ. Feasibility and efficacy of infection control interventions to reduce the number of nosocomial infections and drug resistant microorganisms in developing countries: what else do we need? CID 2009;48:22-24 • EARS-Net. http://www.ecdc.europa.eu/en/activities/surveillance/EARS-Net/Pages/index.aspx • WHO 2010. Global tuberculosis control http://www.who.int/mediacentre/factsheets/fs104/en/index.html • Special pathogens, in Damani N. Manual of infection prevention and control, 3rd ed. Oxford University Press, Oxford, 2012:183-249.

50. Quiz • When a patient with active tuberculosis has to leave the isolation room for tests, s/he has to wear a N95 mask. T/F? • Admission screening for MRSA encompasses the following specimens: • Nares alone • Nares, wounds, exit sites • Nares, wounds • Nares, exit sites • ESBL genes are transmitted by plasmids and are restricted to Enterobacteriaceae. T/F?