Vancomycin MIC as a predictor of outcome in MRSA bacteraemia in the UK context.
UNLABELLED: Received 29 November 2012; returned 20 February 2013; revised 16 May 2013; accepted 18 May 2013 OBJECTIVES: Raised vancomycin MICs have been associated with poor outcomes for methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia in the USA and mainland Europe. We investigated if...
| Main Authors: | , , , , , , , , |
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| Format: | Journal article |
| Language: | English |
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2013
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| _version_ | 1826289421829275648 |
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| author | Hope, R Blackburn, R Verlander, N Johnson, A Kearns, A Hill, R Hopkins, S Sheridan, E Livermore, D |
| author_facet | Hope, R Blackburn, R Verlander, N Johnson, A Kearns, A Hill, R Hopkins, S Sheridan, E Livermore, D |
| author_sort | Hope, R |
| collection | OXFORD |
| description | UNLABELLED: Received 29 November 2012; returned 20 February 2013; revised 16 May 2013; accepted 18 May 2013 OBJECTIVES: Raised vancomycin MICs have been associated with poor outcomes for methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia in the USA and mainland Europe. We investigated if this also applies in the UK, where EMRSA-15 (clonal complex 22) dominates. METHODS: Isolates from UK patients receiving vancomycin therapy for MRSA bacteraemia in 2008-10 were collected, along with clinical details. Outcomes (i.e. patient survival or bacteraemia resolution) were reported 28 days after vancomycin therapy ended. The relationship between clinical outcome and MIC--as determined by CLSI and BSAC agar dilution methods--was assessed. RESULTS: Among 228 MRSA bacteraemias, 82% were caused by EMRSA-15; 65% of the patients were male and the median age was 70.5 years. MICs correlated between methods, but CLSI agar dilution testing gave a mode at 1 mg/L with only 12% of results either side, whereas the BSAC method gave a mode straddling 0.7-1 mg/L with <4% outliers. Twenty-three percent of patients died, with MRSA contributory in half; another 17% had unresolved bacteraemia at 28 days. Neither death nor unresolved bacteraemia was significantly associated with higher vancomycin MICs by either method. Rifampicin co-therapy had no quantifiable effect on outcome. The patient's age was the only significant correlate of patient outcome (P < 0.01); the underlying medical condition of the patient was important for the resolution of bacteraemia (P < 0.01), though not for overall mortality. CONCLUSIONS: Subtle vancomycin MIC differences did not correlate with worse outcomes for vancomycin monotherapy or for vancomycin/rifampicin co-therapy in MRSA bacteraemia. Regardless of the exact MIC-outcome relationship, detecting such small MIC differences seems unlikely to be reliable in routine laboratories. |
| first_indexed | 2024-03-07T02:28:38Z |
| format | Journal article |
| id | oxford-uuid:a6771718-c2b4-4c1d-814d-a8b4aef2e464 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T02:28:38Z |
| publishDate | 2013 |
| record_format | dspace |
| spelling | oxford-uuid:a6771718-c2b4-4c1d-814d-a8b4aef2e4642022-03-27T02:47:35ZVancomycin MIC as a predictor of outcome in MRSA bacteraemia in the UK context.Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:a6771718-c2b4-4c1d-814d-a8b4aef2e464EnglishSymplectic Elements at Oxford2013Hope, RBlackburn, RVerlander, NJohnson, AKearns, AHill, RHopkins, SSheridan, ELivermore, DUNLABELLED: Received 29 November 2012; returned 20 February 2013; revised 16 May 2013; accepted 18 May 2013 OBJECTIVES: Raised vancomycin MICs have been associated with poor outcomes for methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia in the USA and mainland Europe. We investigated if this also applies in the UK, where EMRSA-15 (clonal complex 22) dominates. METHODS: Isolates from UK patients receiving vancomycin therapy for MRSA bacteraemia in 2008-10 were collected, along with clinical details. Outcomes (i.e. patient survival or bacteraemia resolution) were reported 28 days after vancomycin therapy ended. The relationship between clinical outcome and MIC--as determined by CLSI and BSAC agar dilution methods--was assessed. RESULTS: Among 228 MRSA bacteraemias, 82% were caused by EMRSA-15; 65% of the patients were male and the median age was 70.5 years. MICs correlated between methods, but CLSI agar dilution testing gave a mode at 1 mg/L with only 12% of results either side, whereas the BSAC method gave a mode straddling 0.7-1 mg/L with <4% outliers. Twenty-three percent of patients died, with MRSA contributory in half; another 17% had unresolved bacteraemia at 28 days. Neither death nor unresolved bacteraemia was significantly associated with higher vancomycin MICs by either method. Rifampicin co-therapy had no quantifiable effect on outcome. The patient's age was the only significant correlate of patient outcome (P < 0.01); the underlying medical condition of the patient was important for the resolution of bacteraemia (P < 0.01), though not for overall mortality. CONCLUSIONS: Subtle vancomycin MIC differences did not correlate with worse outcomes for vancomycin monotherapy or for vancomycin/rifampicin co-therapy in MRSA bacteraemia. Regardless of the exact MIC-outcome relationship, detecting such small MIC differences seems unlikely to be reliable in routine laboratories. |
| spellingShingle | Hope, R Blackburn, R Verlander, N Johnson, A Kearns, A Hill, R Hopkins, S Sheridan, E Livermore, D Vancomycin MIC as a predictor of outcome in MRSA bacteraemia in the UK context. |
| title | Vancomycin MIC as a predictor of outcome in MRSA bacteraemia in the UK context. |
| title_full | Vancomycin MIC as a predictor of outcome in MRSA bacteraemia in the UK context. |
| title_fullStr | Vancomycin MIC as a predictor of outcome in MRSA bacteraemia in the UK context. |
| title_full_unstemmed | Vancomycin MIC as a predictor of outcome in MRSA bacteraemia in the UK context. |
| title_short | Vancomycin MIC as a predictor of outcome in MRSA bacteraemia in the UK context. |
| title_sort | vancomycin mic as a predictor of outcome in mrsa bacteraemia in the uk context |
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