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Is vancomycin MIC creep a worldwide phenomenon? Assessment of S. aureus vancomycin MIC in a tertiary university hospital.

Joana S, Pedro P, Elsa G, Filomena M - BMC Res Notes (2013)

Bottom Line: The association of vancomycin treatment failures with increased vancomycin minimum inhibitory concentration (MIC) is a well-recognized problem.Only one isolate per patient was included in the final analysis.We were unable to find in our institution data compatible to the presence of vancomycin MIC creep during the study period.

View Article: PubMed Central - HTML - PubMed

Affiliation: Polyvalent Intensive Care Unit, São Francisco Xavier Hospital, CHLO, Lisbon, Portugal. joanapsilvestre@gmail.com

ABSTRACT

Background: Vancomycin is the primary treatment for infections caused by methicilin-resistant Staphylococcus aureus (MRSA). The association of vancomycin treatment failures with increased vancomycin minimum inhibitory concentration (MIC) is a well-recognized problem. A number of single-centre studies have identified progressive increases in glycopeptide MICs for S. aureus strains over recent years - a phenomenon known as vancomycin MIC creep. It is unknown if this is a worldwide phenomenon or if it is localized to specific centers.

Methods: The aim of this study was to evaluate the trend of vancomycin MIC for isolates of MRSA over a 3-year period in a tertiary university hospital in Portugal. MRSA isolates from samples of patients admitted from January 2007 to December 2009 were assessed. Etest method was used to determine the respective vancomycin MIC. Only one isolate per patient was included in the final analysis.

Results: A total of 93 MRSA isolates were studied. The vancomycin MICs were 0.75, 1, 1.5 and 2 mg/L for 1 (1.1%), 19 (20.4%), 38 (40.9%), 35 (37.6%) isolates, respectively. During the 3 year period, we observed a significant fluctuation in the rate of MRSA with a vancomycin MIC > 1 mg/L (2007: 86.2%; 2008: 93.3%; 2009: 58.8%, p = 0.002). No MRSA isolate presented a MIC > 2 mg/L.

Conclusions: We were unable to find in our institution data compatible to the presence of vancomycin MIC creep during the study period. This phenomenon seems not to be generalized; as a result each institution should systematically monitor MRSA vancomycin MIC over time.

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Related in: MedlinePlus

Vancomycin MIC population distribution 2007 – 09.
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Figure 1: Vancomycin MIC population distribution 2007 – 09.

Mentions: The MIC distribution for vancomycin is displayed in Figure 1. During the 3 year study period, we observed a significant fluctuation in the rate of MRSA with a vancomycin MIC > 1 mg/L (2007: 86.2%, 2008: 93.3%, 2009: 58.8%). Overall MICs for vancomycin declined during the study period. The MIC trends appeared to either plateau or slightly increase between 2007 and 2008, (p = n.s) but decreased in 2009 (p = 0.002).


Is vancomycin MIC creep a worldwide phenomenon? Assessment of S. aureus vancomycin MIC in a tertiary university hospital.

Joana S, Pedro P, Elsa G, Filomena M - BMC Res Notes (2013)

Vancomycin MIC population distribution 2007 – 09.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3585458&req=5

Figure 1: Vancomycin MIC population distribution 2007 – 09.
Mentions: The MIC distribution for vancomycin is displayed in Figure 1. During the 3 year study period, we observed a significant fluctuation in the rate of MRSA with a vancomycin MIC > 1 mg/L (2007: 86.2%, 2008: 93.3%, 2009: 58.8%). Overall MICs for vancomycin declined during the study period. The MIC trends appeared to either plateau or slightly increase between 2007 and 2008, (p = n.s) but decreased in 2009 (p = 0.002).

Bottom Line: The association of vancomycin treatment failures with increased vancomycin minimum inhibitory concentration (MIC) is a well-recognized problem.Only one isolate per patient was included in the final analysis.We were unable to find in our institution data compatible to the presence of vancomycin MIC creep during the study period.

View Article: PubMed Central - HTML - PubMed

Affiliation: Polyvalent Intensive Care Unit, São Francisco Xavier Hospital, CHLO, Lisbon, Portugal. joanapsilvestre@gmail.com

ABSTRACT

Background: Vancomycin is the primary treatment for infections caused by methicilin-resistant Staphylococcus aureus (MRSA). The association of vancomycin treatment failures with increased vancomycin minimum inhibitory concentration (MIC) is a well-recognized problem. A number of single-centre studies have identified progressive increases in glycopeptide MICs for S. aureus strains over recent years - a phenomenon known as vancomycin MIC creep. It is unknown if this is a worldwide phenomenon or if it is localized to specific centers.

Methods: The aim of this study was to evaluate the trend of vancomycin MIC for isolates of MRSA over a 3-year period in a tertiary university hospital in Portugal. MRSA isolates from samples of patients admitted from January 2007 to December 2009 were assessed. Etest method was used to determine the respective vancomycin MIC. Only one isolate per patient was included in the final analysis.

Results: A total of 93 MRSA isolates were studied. The vancomycin MICs were 0.75, 1, 1.5 and 2 mg/L for 1 (1.1%), 19 (20.4%), 38 (40.9%), 35 (37.6%) isolates, respectively. During the 3 year period, we observed a significant fluctuation in the rate of MRSA with a vancomycin MIC > 1 mg/L (2007: 86.2%; 2008: 93.3%; 2009: 58.8%, p = 0.002). No MRSA isolate presented a MIC > 2 mg/L.

Conclusions: We were unable to find in our institution data compatible to the presence of vancomycin MIC creep during the study period. This phenomenon seems not to be generalized; as a result each institution should systematically monitor MRSA vancomycin MIC over time.

Show MeSH
Related in: MedlinePlus