Comparison of E-test and broth microdilution methods to determine the minimum inhibitory concentration in methicillin-resistant Staphylococcus aureus
Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
Since 1996 it has been known that MRSA (methicillin-resistant Staphylococcus aureus) can become resistant against the antibiotic vancomycin. The number of resistant cases increase constantly which cause worries. The method E-test is used in clinical usage to determine resistance but the reliability is questioned.
The aim of this study was to validate BMD that can be applied as ISO-standard within clinic usage.
BMD (broth microdilution) was performed to determine the resistance of methicillin resistant Staphylococcus aureus against vancomycin and compared to an E-test. For both tests, 69 clinical isolates, collected during 2013 from Uppsala University Hospital were used. For BMD, additional tests to verify the result was performed if a positive test found. The proportion of VISA (vancomycin-resistant Staphylococcus aureus) among total MRSA samples collected in Uppsala was also studied.
The MICs (minimum inhibitory concentration) obtained through E-test showed that the number of cases were 0 for MIC 0,5 mg/L, 35 for 1 mg/L and 34 for 2 mg/L. With regard to BMD the number cases were 42 for 0,5 mg/L, 12 for 1 mg/L and 15 for 2 mg/L.
Results for the validation tests showed little dispersion for the precision measure, although reproducibility was higher but satisfactory. The MIC values obtained with BMD showed to be a more reliable analysis than the E-test since the BMD detected lower MIC values than the E-test.
Although the E-test is less expensive and easier to perform, BMD is used more often in the near future because of better reliability which leads to a better treatment of the infected patient.
Place, publisher, year, edition, pages
2014. , 15 p.
VSSA, hVISA, VISA, validation, vancomycin
Biomedical Laboratory Science/Technology
IdentifiersURN: urn:nbn:se:uu:diva-228936DOI: 15.OAI: oai:DiVA.org:uu-228936DiVA: diva2:735239
Biomedical Laboratory Science Programme
Stavreus-Evers, Anneli, Docent