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Role of MRSA Swabs for De-escalation of Antibiotics in HCAP

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Presentation on theme: "Role of MRSA Swabs for De-escalation of Antibiotics in HCAP"— Presentation transcript:

1 Role of MRSA Swabs for De-escalation of Antibiotics in HCAP
Colleen Linsenmayer, Pharm.D. PGY2 Internal Medicine Pharmacy Resident Richard L. Roudebush VA Medical Center This speaker has no actual or potential conflicts of interest to disclose in relation to this presentation

2 Methicillin-resistant Staphylococcus aureus (MRSA)
Increasingly important pathogen in pulmonary infections Incidence of MRSA healthcare-associated pneumonia (HCAP) is predicted to be %. Associated with significant morbidity and mortality IDSA Guidelines, citation 1 Incidence depends on patient risk factors and local epidemiological patterns MRSA pneumonia is associated with significant morbidity and mortality particularly if antibiotic therapy targeting MRSA is not included in an initial empirical regimen. https://depts.washington.edu/hhpccweb/content/clinics/family-health/antibiotic-resistant-staph-infections-mrsa Niederman MS et al. Am J Respir Crit Care Med. 2005;171: Dangerfield B et al. Antimicrobial Agents Chemother. 2014;58(2):

3 IDSA HAP Guidelines Late onset (≥5 Days) or risk factors for
HAP, VAP or HCAP suspected Late onset (≥5 Days) or risk factors for multi-drug resistant (MDR) pathogens Broad spectrum antibiotic therapy for MDR pathogens (Including MRSA) Risk factors: Niederman MS et al. Am J Respir Crit Care Med. 2005;171:

4 IDSA HAP Guidelines How do you de-escalate in absence of adequate
Consider de-escalation of antibiotic based on: Results of lower respiratory tract cultures are available Patient’s clinical response How do you de-escalate in absence of adequate lower-respiratory cultures? And to combat overuse of antibiotics the IDSA guidelines so recommend de-escalation based on microbiological cultures and clinical response of the patient However what they did not address how to de-escalate antibiotics in the absence of adequate cultures which is commonly the case in many of our patients. Many physicians are reluctant to discontinue or de-escalate empiric antibiotics when cultures are unavailable. One way to determine safety and appropriateness of de-escalation is to evaluate the patient for the presence or absence of colonization Niederman MS et al. Am J Respir Crit Care Med. 2005;171:

5 Pathogenesis Entry of MRSA Colonization Aspiration Infection
HAP requires the entry of microbial pathogens into the lower respiratory tract, followed by colonization, which can then over-whelm the host’s mechanical (ciliated epithelium and mucus), humoral (antibody and complement), and cellular (polymorpho-nuclear leukocytes, macrophages, and lymphocytes and their respective cytokines) defenses to establish infection. Aspiration of oropharyngeal pathogens or leakage of bacteria around the endotracheal tube cuff is the primary route of bacterial entry into the trachea Patients are most likely to develop HCAP due to a MDR pathogen following aspiration of the organism from the patient’s oropharynx Niederman MS et al. Am J Respir Crit Care Med. 2005;171:

6 MRSA Colonization Identifying patients with MRSA colonization may guide initial antibiotic treatment and isolation measures MRSA swabbing is a standard method for screening in many facilities for MRSA screening Patients colonized with MRSA are at a higher rate of infection and act as a resevoir for potential transmission to other patients Nasal MRSA screening has been shown to be the most sensitive at detecting patients who are MRSA carriers Dangerfield B et al. Antimicrobial Agents Chemother. 2014;58(2):

7 MRSA Nasal Colonization
MRSA nasal colonization can be reliably detected using nasal swab PCR test Presence of MRSA nasal colonization has been correlated with the development of subsequent MRSA infections Most patients with HCAP due to MDR organisms develop infection following aspiration of the organism for patient’s oropharynx followed by tracheal colonization MRSA nasal swabs can have a powerful impact on the course of therapy depending on whether positive or negative Dangerfield B et al. Antimicrobial Agents Chemother. 2014;58(2): Boyce JM et al. Antimicrobial Agents Chemother. 2013;57(3):

8 Predictive Value of MRSA Nasal Swabs for MRSA Pneumonia
Test Characteristic Result 95% Confidence Interval Sensitivity (%) 88.0 67.6 – 96.9 Specificity (%) 90.1 86.6 – 92.8 Positive predictive value (%) 35.4 24.0 – 48.7 Negative predictive value (%) 99.2 97.4 – 99.8 Authors found that the nasal MRSA PCR test has a mediocre positive predictive value but an excellent negative predictive value for MRSA pneumonia PCR testing was usually ordered for clincal diagnostic purposes (in both ICU and IM patients) Included CAP, HCAP, and HAP. HCAP (the largest pt group with n = 238) actually found a 100% NPV Clinical implication of these results is that patients treated empirically with antibiotics to treat MRSA may be reasonably used to guide de-escalation Dangerfield B et al. Antimicrobial Agents Chemother. 2014;58(2):859-62

9 MRSA Nasal Swabs - Negative Predictive Value (NPV)
Clinical Trial Population Culture Site NPV Harris et al. Non-ICU Any Body Site 98% Robicsek et al. All admissions/ ICU transfers Robissek et al (Subgroup) Respiratory Sarikonda et al ICU 84.4% Additional studies looking at negative predictive value of MRSA swabs Difference in NPV in this trial may be attributed to all ICU pts vs mixed and higher prevalence of colonization and infection Harris AD et al. Antimicrobial Agents Chemother. 2010;54(8): Robicsek A, et al. J Clin Microbiol ;46(2): Sarikonda KV, et al. Crit Care Med. 2010;38(10):

10 Clinical Implications
Patients treated empirically with antibiotics to treat MRSA may reasonably used to guide de-escalation Piperacillin/Tazobactam + Vancomycin Clinical implication of these results is that patients treated empirically with antibiotics to treat MRSA may be reasonably used to guide de-escalation Dangerfield B et al. Antimicrobial Agents Chemother. 2014;58(2): Boyce JM et al. Antimicrobial Agents Chemother. 2013;57(3):

11 Discontinuation of Empiric Vancomycin
Population: patient receiving empiric vancomycin for suspected or proven HCAP with no adequate lower-respiratory cultures If nasal + throat MRSA cultures were negative then de-escalation of vancomycin was recommended Results: no difference in mortality compared to previous study of pneumonia patients who underwent de-escalation of antibiotics when respiratory cultures were not obtained Take home message by the authors was that when there was no difference in mortality when vancomycin was discontinued The in-hospital mortality in our study (7.7%) was similar to a mortality rate of 10.7% in a previous study of pneumonia patients who underwent de-escalation of antibiotics when respiratory cultures were not obtained Boyce JM et al. Antimicrobial Agents Chemother. 2013;57(3):

12 Debunking Myths “The patient’s nasal swab may be negative because they received empiric vancomycin therapy prior to the admission nasal swab” Vancomycin has been shown to have little effect on staphylococcus aureus nasal colonization and seldom would eradicate MRSA in the first several days of therapy Boyce et al Boyce JM et al. Antimicrobial Agents Chemother. 2013;57(3):

13 Clinical Pearl Patie nt meet s the follo wing criter ia:
Empiric HCAP Treatment Patie nt meet s the follo wing criter ia: 1) Blood cultur es negati ve x 48 hours 2) Negat ive MRSA nasal swab Consider discontinuation of MRSA-directed antibiotic

14 Summary MRSA pneumonia is unlikely in patients who are not colonized and have no evidence of MRSA bacteremia Data suggests that MRSA PCR nasal swabs have negative predictive value of up to 99% for MRSA pneumonia A negative MRSA swab can be reasonably used to guide antibiotic de-escalation for HCAP

15 Role of MRSA Swabs for De-escalation of Antibiotics in HCAP
Colleen Linsenmayer, Pharm.D. PGY2 Internal Medicine Pharmacy Resident Richard L. Roudebush VA Medical Center


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