1. Three Rivers Antimicrobial Stewardship Symposium
Use of negative MRSA nares swabs to support discontinuation of vancomycin in patients with pneumonia
Saturday, March 9th, 2019
Three Rivers Antimicrobial Stewardship Symposium
​Use of negative MRSA swabs to support discontinuation of anti-MRSA antibiotics in UPMC Shadyside patients with pneumonia
Louise-Marie Oleksiuk, PharmD, BCPS
UPMC Presbyterian Shadyside – Shadyside Campus
Antimicrobial Stewardship Program

2. Learning Objectives
Describe how MRSA nares swabs can be used to help de-escalate intravenous vancomycin in patients being treated for pneumonia
List some shortcomings of using MRSA nares swabs to de-escalate vancomycin therapy

3. Local Rationale HIGH vancomycin utilization
MRSA nasal swabs: negative predictive value (>95%) for pneumonia
Confirmed for Shadyside

4. Local Vancomycin Utilization
Pneumonia treated with vancomycin
Vancomycin
utilization for alternate indications
Pneumonia treated with alternate antibiotics
Of vancomycin use: ~30% pneumonia
Of patients with pneumonia: ~45% receive vancomycin

5. Vancomycin Utilization for Pneumonia (non-ICU)
Characteristics
Baseline period
(1/2017 – 3/2017)
N = 59
Age (years), median (range)
75 (29-94)
Admitting service: family practice, internal/general medicine, n (%)
45 (76)
Length of stay (days), median (range)
9 (2-36)
History of MRSA colonization, n (%)
5 (8)
Duration of IV vancomycin therapy (days), median (range)
6 (2-18)
IV vancomycin re-initiation, n (%) --
Infectious Diseases consultation, n (%)
19 (32)
Pharmacokinetics Service consultation, n (%)
25 (42)
Inpatient mortality, n (%)
30-day readmission, n (%)
11 (18)
Adequate respiratory samples: ~1%
INSERT RISK FACTORS FOR MDR PATHOGENS – explain issue with lack of respiratory culture being that national guidelines center their de-escalation recommendations around the availability of culture data

6. Can a negative MRSA-nasal swab be used to rule-out MRSA pneumonia?

7. Definition – Negative Predictive Value (NPV)
Test versus disease table
Test Result
Disease (n)
No Disease (n)
Totals
Positive (n) A
(true positive) B
(false positive)
Positive total (n)
Negative (n) C
(false negative) D
(true negative)
Negative total (n)
Disease total (n)
No Disease total (n)
All total (n)
Test versus disease table

8. Definition – Negative Predictive Value (NPV)
Test versus disease table
Test Result
Disease (n)
No Disease (n)
Totals
Positive (n) A
(true positive) B
(false positive)
Positive total (n)
Negative (n) C
(false negative) D
(true negative)
Negative total (n)
Disease total (n)
No Disease total (n)
All total (n)
The percentage of patients with a negative test who do not have the disease = (D / [C+D]) x 100
Influenced by prevalence of disease in population being tested
Prevalence ↑, NPV ↓
Test versus disease table

9. Clinical Utility of MRSA Nasal Screening
2018 meta-analysis
Evaluate diagnostic value of MRSA nasal screening in MRSA pneumonia
N = 22 studies (5,163 patients)
Pneumonia classification (n=11)
VAP = 5
CAP, HCAP, VAP = 3
CAP, HCAP = 2
“Nosocomial” = 1
Nares screening
PCR (2 hours, $26) = 11
Chromogenic agar (2 days, $7) = 4
Largely retrospective studies (18 – 81%)
Diagnostic criteria for pneumonia varied but largely radiographic evidence of pneumonia, respiratory cultures, clinical criteria
Majority done within 24 hours of admission to hospital or ICU
Parente DM, et al. Clin Infect Dis 2018;67(1):1-7

10. Results Pooled prevalence of MRSA pneumonia: 10% Type of Pneumonia
No. Studies
Sensitivity, %
(95% CI)
Specificity, %
PPV, %
NPV, %
All 22
70.9
( )
90.3
( )
44.8
96.5
CAP/HCAP 4 85
( )
92.1
( )
56.8
98.1
VAP 5
40.3
( )
93.7
( )
35.7
94.8
Parente DM, et al. Clin Infect Dis 2018;67(1):1-7

11. UPMC Shadyside Experience

12. Local Prevalence (2016) MRSA detected in respiratory culture
MRSA Prevalence
Respiratory culture
Overall
6.4% (84/1,308)
ICU
8.4% (54/642)
Non-ICU
4.5% (30/666)
MRSA nasal swabs: negative predictive value (>95%) for pneumonia
Confirmed for Shadyside

13. Local NPV
MRSA nasal swab result within 7 days before respiratory culture
Test Result
MRSA in Respiratory Sample
No MRSA in Respiratory Sample
Totals
MRSA nasal swab (+) 16 9 25
MRSA nasal swab (-) 8
248
256 24
257
281
MRSA nasal swabs: negative predictive value (>95%) for pneumonia
Confirmed for Shadyside
MRSA nasal swab result within 7 days before respiratory culture
8.5% (24/281)
11.2% (18/161)
5% (6/120)
NPV: 96.9%
ICU: 95.8%
Non-ICU: 98.2%

14. Antimicrobial Stewardship Intervention
Educate pharmacists and prescribers
Vancomycin utilization rates vs prevalence
NPV of MRSA nasal swab
Recommend ordering MRSA nasal swab (and respiratory culture) when starting empiric vancomycin for pneumonia
Prospective audit with intervention and feedback (“timeouts”)
Antimicrobial stewardship, decentralized, rounding, pharmacokinetics pharmacists

15. Vancomycin De-escalation
Respiratory Sample
MRSA Nasal Swab1
**MRSA** in patient identification banner
Recommendation2
(discussed with provider)
MRSA
N/A
Yes
No intervention
No MRSA
Recommend discontinuation of anti-MRSA therapy
None performed or “normal respiratory flora”
POSITIVE (MRSA)
NEGATIVE (No MRSA)
Yes or No
Recommend discontinuation of anti-MRSA therapy3
Within 7 days of onset of pneumonia
Results from adequate respiratory specimens should always supersede MRSA swab findings
MRSA nasal swab should not be used to guide antibiotic de-escalation in patients with:
Concurrent indication for vancomycin/anti-MRSA therapy
Recent nasal decolonization before screening
MRSA infection within 30 days before onset of pneumonia
Clinical findings associated with higher prevalence of S. aureus pneumonia
Empyema, lung abscess, necrotizing or cavitary infiltrates, preceding or concurrent viral pneumonia (e.g. influenza), history of MRSA pneumonia (including Cystic Fibrosis).

16. Q. Which of the following represents a scenario where an MRSA nares swab should NOT be used to guide vancomycin de-escalation in patients with pneumonia?
Local prevalence of MRSA pneumonia ~5%
Pulmonary culture growing S.pneumoniae
No other indication for intravenous vancomycin (aside from pneumonia)
No clinical findings associated with higher prevalence of S.aureus pneumonia (e.g. empyema, lung abscess, necrotizing or cavitary infiltrates, preceding or concurrent viral pneumonia)

17. Q. Which of the following represent(s) shortcomings of using MRSA nares swabs to guide vancomycin de-escalation?
Negative predictive value is influenced by prevalence of disease in population
Time associated with specimen processing if using chromogenic agar
Unclear utility in patients presenting with clinical findings associated with higher prevalence of S.aureus pneumonia (e.g. preceding or concurrent viral pneumonia)
All of the above represent shortcomings

18. Local Impact (Results)
UPMC Presbyterian Shadyside Quality Fair (2019)
1st Place in Quality

19. Local Impact (Results continued) Vancomycin Utilization for Pneumonia
Characteristics
Baseline period
(1/2017 – 3/2017)
Post-implementation
(7/2017 – 3/2018)
N = 59
N = 92
Age (years), median (range)
75 (29-94)
74 (28-102)
Admitting service: family practice, internal/general medicine, n (%)
45 (76)
73 (79)
Length of stay (days), median (range)
9 (2-36)
9 (3-55)
History of MRSA colonization, n (%)
5 (8)
2 (2)
Duration of IV vancomycin therapy (days), median (range)
6 (2-18)
3 (2-7)
IV vancomycin re-initiation, n (%) --
6 (6)
Infectious Diseases consultation, n (%)
19 (32)
31 (34)
Pharmacokinetics Service consultation, n (%)
25 (42)
79 (86)
Inpatient mortality, n (%)
7 (8)
30-day readmission, n (%)
11 (18)
20 (22)
INSERT RISK FACTORS FOR MDR PATHOGENS – explain issue with lack of respiratory culture being that national guidelines center their de-escalation recommendations around the availability of culture data
*Time from MRSA nasal swab collection to results (days), median (range): 2 (1-3)

20. Project Timeline
Oct-Dec 2016
↑vancomycin utilization
Jan-Apr 2017
Pneumonia opportunity for intervention
MRSA nasal swabs may help
May 2017
Evaluate local prevalence of MRSA pneumonia and corresponding NPV of MRSA nasal swab
Develop local intervention
June-July 2017
Educate pharmacists and prescribers on appropriate use of MRSA nasal swabs to guide vancomycin de-escalation in patients with pneumonia
July 2017 – Present
Prospective audit with intervention & feedback for vancomycin (“48-72 hour timeouts)
November 2018
Local protocol approved by P&T to allow automatic pharmacist ordering of MRSA nasal swabs in patients on vancomycin for pneumonia
MRSA nasal swabs: negative predictive value (>95%) for pneumonia
Confirmed for Shadyside

21. Barriers and Lessons Learned
Limited impact on inappropriate empiric vancomycin initiation (outdated treatment guidelines)
Ensuring timely MRSA nasal swab ordering (initially)
MRSA sample collection required reminders
MRSA nasal swab processing time: 48 hours
Prospective audit with intervention and feedback is time-consuming
Use of MRSA nasal swabs was a well-accepted (required few repeat interventions)
Successfully used “antibiotic timeouts” as recommended by the new Joint Commission medication management standard on antimicrobial stewardship

22. Future Research
Added experience using it as antimicrobial stewardship tool
Evaluate utility of MRSA nares screen in patients with pneumonia and concomitant risk factors or clinical presentations suggestive for MRSA pneumonia
Clinical utility in other infections
Carr AL, et al. Pharmacotherapy 2018;doi: /phar.2188

23. Acknowledgements Physicians Pharmacists David R. Weber, MD
Robert L. Volosky, MD
John Zisko, MD
Maria Guyette, MD
Nathan Shively, MD
Pharmacists
Frances Youschak, PharmD
Erica Gray, PharmD
Brian Tuttle, RPh

24. Use of negative MRSA nares swabs to support discontinuation of vancomycin in patients with pneumonia
Three Rivers Antimicrobial Stewardship Symposium
Louise-Marie Oleksiuk, PharmD, BCPS
UPMC Presbyterian Shadyside – Shadyside Campus
Antimicrobial Stewardship Program