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Impact of biofilm on the in vitro activity of vancomycin alone and in combination with tigecycline and rifampicin against Staphylococcus aureus.
J Antimicrob Chemother. 2009 Mar; 63(3):485-8.JA

Abstract

OBJECTIVES

This study evaluated vancomycin susceptibility and activity alone and in combination with rifampicin and tigecycline against low-biofilm- and high-biofilm-producing methicillin-resistant Staphylococcus aureus (MRSA) clinical isolates.

METHODS

Forty MRSA isolates recovered from bloodstream infections were analysed. Susceptibilities were performed in planktonic and biofilm cultures by microbroth dilution. Biofilm production was determined using an adherent plate assay. Time-kill analysis was performed on six low- and six high-biofilm-producing isolates with 15 mg/L vancomycin alone and in combination with rifampicin or tigecycline at 4x MIC.

RESULTS

Vancomycin susceptibility displayed a 4-fold and an 8-fold increase in the MIC(50) and MIC(90), respectively, in the presence of biofilm. Rifampicin and tigecycline susceptibilities also increased in biofilms, but still remained within the susceptibility breakpoints except for a tigecycline MIC(90) of 1 mg/L. High biofilm production was detected in 60% of the isolates. In time-kill analysis, 15 mg/L vancomycin achieved bactericidal activity against only low-biofilm-producing strains with a 1.8 log(10) cfu/mL difference in bacterial kill compared with high-biofilm-producing strains (P < 0.001). Rifampicin alone had minimal activity, resulting in resistance. Tigecycline was minimally effective and was not bactericidal, but no difference was observed in the comparison of biofilm-producing strains. Vancomycin in combination with rifampicin or tigecycline was bactericidal against all strains (mean kill 4.5 +/- 0.5 log(10) cfu/mL), regardless of biofilm production.

CONCLUSIONS

Vancomycin exposures at 15 mg/L may not be adequate in eradicating biofilm-producing S. aureus. Alternative treatments or combination therapy should be explored to optimize outcomes in biofilm-associated infections.

Authors+Show Affiliations

Pharmacy Practice Division, School of Pharmacy, University of Wisconsin, Madison, WI 53705, USA. werose@pharmacy.wisc.eduNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

19109338

Citation

Rose, Warren E., and Peter T. Poppens. "Impact of Biofilm On the in Vitro Activity of Vancomycin Alone and in Combination With Tigecycline and Rifampicin Against Staphylococcus Aureus." The Journal of Antimicrobial Chemotherapy, vol. 63, no. 3, 2009, pp. 485-8.
Rose WE, Poppens PT. Impact of biofilm on the in vitro activity of vancomycin alone and in combination with tigecycline and rifampicin against Staphylococcus aureus. J Antimicrob Chemother. 2009;63(3):485-8.
Rose, W. E., & Poppens, P. T. (2009). Impact of biofilm on the in vitro activity of vancomycin alone and in combination with tigecycline and rifampicin against Staphylococcus aureus. The Journal of Antimicrobial Chemotherapy, 63(3), 485-8. https://doi.org/10.1093/jac/dkn513
Rose WE, Poppens PT. Impact of Biofilm On the in Vitro Activity of Vancomycin Alone and in Combination With Tigecycline and Rifampicin Against Staphylococcus Aureus. J Antimicrob Chemother. 2009;63(3):485-8. PubMed PMID: 19109338.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Impact of biofilm on the in vitro activity of vancomycin alone and in combination with tigecycline and rifampicin against Staphylococcus aureus. AU - Rose,Warren E, AU - Poppens,Peter T, Y1 - 2008/12/24/ PY - 2008/12/26/entrez PY - 2008/12/26/pubmed PY - 2009/3/21/medline SP - 485 EP - 8 JF - The Journal of antimicrobial chemotherapy JO - J Antimicrob Chemother VL - 63 IS - 3 N2 - OBJECTIVES: This study evaluated vancomycin susceptibility and activity alone and in combination with rifampicin and tigecycline against low-biofilm- and high-biofilm-producing methicillin-resistant Staphylococcus aureus (MRSA) clinical isolates. METHODS: Forty MRSA isolates recovered from bloodstream infections were analysed. Susceptibilities were performed in planktonic and biofilm cultures by microbroth dilution. Biofilm production was determined using an adherent plate assay. Time-kill analysis was performed on six low- and six high-biofilm-producing isolates with 15 mg/L vancomycin alone and in combination with rifampicin or tigecycline at 4x MIC. RESULTS: Vancomycin susceptibility displayed a 4-fold and an 8-fold increase in the MIC(50) and MIC(90), respectively, in the presence of biofilm. Rifampicin and tigecycline susceptibilities also increased in biofilms, but still remained within the susceptibility breakpoints except for a tigecycline MIC(90) of 1 mg/L. High biofilm production was detected in 60% of the isolates. In time-kill analysis, 15 mg/L vancomycin achieved bactericidal activity against only low-biofilm-producing strains with a 1.8 log(10) cfu/mL difference in bacterial kill compared with high-biofilm-producing strains (P < 0.001). Rifampicin alone had minimal activity, resulting in resistance. Tigecycline was minimally effective and was not bactericidal, but no difference was observed in the comparison of biofilm-producing strains. Vancomycin in combination with rifampicin or tigecycline was bactericidal against all strains (mean kill 4.5 +/- 0.5 log(10) cfu/mL), regardless of biofilm production. CONCLUSIONS: Vancomycin exposures at 15 mg/L may not be adequate in eradicating biofilm-producing S. aureus. Alternative treatments or combination therapy should be explored to optimize outcomes in biofilm-associated infections. SN - 1460-2091 UR - https://www.unboundmedicine.com/medline/citation/19109338/Impact_of_biofilm_on_the_in_vitro_activity_of_vancomycin_alone_and_in_combination_with_tigecycline_and_rifampicin_against_Staphylococcus_aureus_ L2 - https://academic.oup.com/jac/article-lookup/doi/10.1093/jac/dkn513 DB - PRIME DP - Unbound Medicine ER -