When Is it Safe  To Discontinue Isolation

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Acknowledgements. David J. Weber, MD, MPHMedical DirectorHospital EpidemiologyAssociate Chief of StaffUNC HospitalsChapel Hill, NC. Airborne for those diseases known to be transmitted via the airborne routeTB, varicellaDroplet for those diseases known to be transmitted via respiratory dropletsInvasive meningiococcal disease, pertussis, influenzaContact for those diseases known to be transmitted via direct contact or indirectly via a contaminated objectCDAD, VRE, MRSA.

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When Is it Safe To Discontinue Isolation

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1. When Is it Safe To Discontinue Isolation? Vickie Brown, RN, MPH, CIC Associate Director Hospital Epidemiology UNC Hospitals Chapel Hill, North Carolina

2. Acknowledgements David J. Weber, MD, MPH Medical Director Hospital Epidemiology Associate Chief of Staff UNC Hospitals Chapel Hill, NC

3. Airborne for those diseases known to be transmitted via the airborne route TB, varicella Droplet for those diseases known to be transmitted via respiratory droplets Invasive meningiococcal disease, pertussis, influenza Contact for those diseases known to be transmitted via direct contact or indirectly via a contaminated object CDAD, VRE, MRSA Major Isolation Categories

4. Questions To Ask? Is the Pathogen Normal Flora? Is the pathogen in a secretion/body substance such as respiratory secretions or stool? If present, is it sufficient dose/route to lead to transmission?

5. More Considerations Is the period of communicability related to: Time? (e.g., Influenza, parvovirus) Symptom resolution? (e.g., CDAD, varicella, measles) Lab-based? (e.g., MRSA, VRE)

6. References Guidelines for Isolation Precautions: Preventing Transmission of Infectious Agents in Healthcare Settings 2007 Centers for Disease Control and Prevention Control of Communicable Diseases Manuel, 2004 American Public Health Association Red Book, 2006 American Academy of Pediatrics

7. Influenza Viral shedding in respiratory secretions is usually limited to 5 – 7 days CDC 2007 Isolation Guidelines: Droplet Precautions for 5 days after onset of illness

8. Viral Shedding of Influenza Meta-analysis of 56 studies with 1,280 healthy participants challenged with an influenza virus (1091) Type A, (189) Type B Sharp increase in shedding between 0.5 and 1 day after challenge Consistently peaked on day 2 Duration of viral shedding (375 participants) was 4.80 days (95% confidence interval: 4.31,5.29)

9. Influenza B and Prolonged Shedding 214 patients underwent viral isolation before, and between, days 4 and 6 after an initial dose of oseltamivir Re-isolation rates of influenza B was significantly higher than for influenza A across all age groups (p-value <0.001) Re-isolation rates for both types of influenza were higher for children 0-15 years

11. Recommendation for Discontinuing Isolation CDC 2007 Isolation Guidelines: 5 days after onset of symptoms Immunocompetent population: 5 days Hospitalized population with patients at risk of pneumonia ( e.g., chronic lung diseases, immunosuppressed, neonates and elderly): Adults – 7 to 10 days Children – 10 days

12. Norovirus Viral shedding in stool is mostly limited to symptomatic period CDC 2007 Isolation Guidelines: duration of illness Prolonged shedding can occur especially in immunocompromised

13. Prolonged Shedding of Norovirus Sample of 10 elderly patients ( age 79-94 years), the median excretion of norovirus was 8.6 days (range 2-15 days)1 Sample of 26 children (age 3 mo-3 years, the median excretion of norovirus was 16 days with a range of 5-47 days. For children <1 year (6/8) norovirus was detected more than 2 weeks after onset2

14. Recommendation for Discontinuing Isolation CDC 2007 Isolation Guidelines: Contact Isolation needed for duration of illness Generally interpreted as isolation can be stopped once diarrhea has resolved. Outbreak that is not controlled by above recommendation and appropriate surface decontamination: Consider prolonging isolation for up to 2 weeks especially in elderly and young children

15. C. difficile Occasionally normal flora, found in < 3% of healthy adults Once diarrhea stopped, C. difficile may still be present in stool but the amount excreted in stool and the amount of environmental contamination is reduced Assays may remain positive

16. Clostridium difficile Skin Contamination

17. Persistence of Skin Contamination

18. Recommendation for Discontinuing Isolation CDC 2007 Isolation Guidelines: Contact Isolation needed for duration of illness Generally interpreted as isolation can be stopped once diarrhea has resolved. Outbreak that is not controlled by above recommendation along with appropriate surface decontamination: Consider prolonging isolation for 7-10 days after diarrhea resolved

19. Multi-drug Resistant Organisms (MDROs) Significant pathogens for hospitalized populations: Methicillin-resistant S. aureus (MRSA) Vancomycin-resistant enterococcus (VRE) MDR Gram-negative: Acinetobacter sp., pseudomonas aeruginosa MDR defined as susceptible to <2 classes of antibiotics

20. Management of Multidrug-resistant Organisms in Healthcare Settings, 2006 Background information: In general, it seems reasonable to discontinue Contact Precautions when three or more surveillance cultures for the targeted MDRO are repeatedly negative over the course of a week or two in a patient who has not received antimicrobial therapy for several weeks, especially in the absence of a draining wound, profuse respiratory secretions, or evidence implicating the specific patient in ongoing transmission of the MDRO within the facility. No recommendation for when to D/C Contact Precautions…unresolved issue. Guidelines do recommend the use of a computer system to record long term isolation indicators for patients colonized with MRSA, VRE, VISA, or VRSA so that on return to the hospital an alert will be provided of the need for isolation (1B)

21. 2003 SHEA Guidelines for MRSA and VRE No specific recommendation for when isolation can be discontinued

22. MRSA S. aureus, including those strains that are methicillin and oxacillin resistant, frequently colonizes humans and is considered normal flora Found in respiratory secretions, skin, vaginal secretions and stool Colonization lasts for months to years Capable of being transmitted in the carrier state

23. MRSA Multiple studies have shown that persons can stay colonized with MRSA for long periods of time and that carriage can be intermittent Current control measures include active surveillance cultures for early identification and isolation Discontinuing isolation too soon may increase the risk of transmission within a healthcare facility

24. MRSA: Duration of Carriage Study conducted in the Netherlands involved 135 patients positive for MRSA upon discharge from the hospital Patients were assessed every 6 months for carriage and MRSA risk factors At 6 months: 121 patients assessed, 60% (72) remained positive At 1 year: 99 patients assessed, 22% (22 patients) remained positive At 2 years: 47 patients assessed, 13% (6) remained positive

25. Virens Study Con’t. Eradication therapy* provided to 31 patients without risk factors for MRSA carriage Eradication treatment effective for 95% of the patients within 1 year * mupirocin nasal ointment combined with chlorhexidine body and hair washing for 5 days, GI carriage: antibiotic therapy provided

26. MRSA: Duration of Carriage Prospective 10 month study involving 78 patients admitted to a 1200 bed French hospital who were known to have MRSA from a previous admission All were readmitted >3 mo after the end of the previous stay 40% remained positive at time of readmission The median time to a negative MRSA screen was 8.5 mo

28. Recommendation for Discontinuing Isolation Off antibiotics for a minimum of 1 week, extend to 3 weeks if on dialysis 3 negative cultures (or PCR) from the original site and from the nares Obtain 1 week apart Decolonization therapy does not alter above

29. VRE Enterococcus is normal flora found in the GI tract, vagina, and oral cavity Found in large numbers in human stool Colonization with vancomycin resistant strains can be prolonged…years in some cases

30. VRE and Length of Colonization 116 patients hospitalized at the University of Virginia Hospital who were identified with VRE F/u cultures obtained on outpatient visits or during hospital stay First f/u culture was collected a mean of 125 days after the initial positive isolate

31. Byers Con’t After 1st f/u culture: 64% negative After 1st negative f/u culture: 92% negative After 2 negative f/u cultures: 95% remained culture negative 22 patients remained persistently colonized for >100 days, including one patient who remained colonized 709 days after the initial isolation

32. Recurrence of VRE 16 patients who had cleared VRE colonization 3/16 received no antibiotics during study period and remained VRE negative (f/u cultures obtained an average of 5 mo since initial 3 negatives) 13/16 patients received antibiotics during the study period 8/13 (62%) developed recurrent VRE PFGE suggested that both relapse and acquisition of a new strain occurred

33. Recommendation for Discontinuing Isolation 3 negative stool cultures collected off antibiotics and collected 1 week apart is sufficient Consider re-screening patients who receive anti-anaerobic antibiotics, esp. if VRE colonization/infection rates are high

34. Acinetobacter species Widely distributed in the environment and can colonize the skin of healthy individuals Studies of healthy military recruits found 17% (17/102) had skin colonization; however, when their isolates were compared to clinical isolates from injured soldiers, none showed genetic similarities* Swab specimens from the nares of 293 healthy soldiers undergoing military training in Texas found no acinetobacter colonization.**

35. Surveillance Cultures Twenty two patients with recent (<10 days) acinetobacter isolates were considered carriers Six body sites sampled with 12 patients having at least 1 positive surveillance culture Overall sensitivity of 55%

36. Sensitivities of Surveillance Cultures

37. Duration of Carriage 140 samples obtained from 30 patients with a remote (> 6 months) history of Acinetobacter baumannii 5 (17%) has at least one positive surveillance culture Length of time from the last clinical isolate ranged from 8-42 months

38. Recommendation for Discontinuing Isolation Do not discontinue for remainder of hospitalization Patients with a known history are isolated upon readmission Isolation is discontinued when: At least 6 months since last positive culture 3 negative surveillance cultures (collected from skin and throat) Surveillance cultures must be collected with patient off antibiotics and at least 1 week apart

39. Immunocompromised Patients Prolonged shedding can occur VZV – skin/oral? Adenovirus – respiratory, urine Cryptosporidium (duration diarrhea) – stool Parainfluenza - respiratory

40. Conclusions Discontinuing isolation is a judgment call based upon published guidelines and research, and assessment of patient population Infection Control Professionals must weigh the negative consequences of isolation with the potential risk of disease transmission to susceptible patients Our first priority is always to protect other patients and employees


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