Dataset Information

Occurrence of cross-resistance and ?-lactam seesaw effect in glycopeptide-, lipopeptide- and lipoglycopeptide-resistant MRSA correlates with membrane phosphatidylglycerol levels.

ABSTRACT:

Background

Glycopeptides (GPs), lipopeptides (LPs) and lipoglycopeptides (LGPs) are related antimicrobials important for the management of invasive MRSA infections. Cross-resistance among these antibiotics in MRSA is well documented, as is the observation that susceptibility of MRSA to ?-lactams increases as susceptibility to GPs and LPs decreases (i.e. the seesaw effect). Efforts to understand the relationship between GP/LP/LGP cross-resistance and the seesaw effect have focused on the PBPs, but the role of lipid metabolism has not been investigated.

Objectives

Since the cell membrane is structurally and metabolically integrated with the cell wall and anchors associated proteins, including PBPs, we examined the relationship between membrane lipid composition and the phenomena of cross-resistance among GPs/LPs/LGPs and the ?-lactam seesaw effect.

Methods

We selected for daptomycin, vancomycin and dalbavancin resistance using the USA300 strain JE2 and evaluated the resulting mutants by WGS, MS-based lipidomics and antimicrobial susceptibility testing to assess the relationship between membrane composition, cross-resistance, and the seesaw effect.

Results

We observed cross-resistance to GPs/LPs/LGPs among the selected strains and the seesaw effect against various ?-lactams, depending on the PBP targets of the particular ?-lactam. We found that modification of membrane composition occurs not only in daptomycin-selected strains, but also vancomycin- and dalbavancin-selected strains. Significantly, we observed that the abundance of most phosphatidylglycerols positively correlates with MICs of GPs/LPs/LGPs and negatively correlates with the MICs of ?-lactams.

Conclusions

These studies demonstrate a major association between membrane remodelling, cross-resistance and the seesaw effect.

SUBMITTER: Hines KM

PROVIDER: S-EPMC7869793 | biostudies-literature | 2020 May

REPOSITORIES: biostudies-literature

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Publications

Occurrence of cross-resistance and β-lactam seesaw effect in glycopeptide-, lipopeptide- and lipoglycopeptide-resistant MRSA correlates with membrane phosphatidylglycerol levels.

Hines Kelly M KM Shen Tianwei T Ashford Nathaniel K NK Waalkes Adam A Penewit Kelsi K Holmes Elizabeth A EA McLean Kathryn K Salipante Stephen J SJ Werth Brian J BJ Xu Libin L

The Journal of antimicrobial chemotherapy 20200501 5

<h4>Background</h4>Glycopeptides (GPs), lipopeptides (LPs) and lipoglycopeptides (LGPs) are related antimicrobials important for the management of invasive MRSA infections. Cross-resistance among these antibiotics in MRSA is well documented, as is the observation that susceptibility of MRSA to β-lactams increases as susceptibility to GPs and LPs decreases (i.e. the seesaw effect). Efforts to understand the relationship between GP/LP/LGP cross-resistance and the seesaw effect have focused on the ...[more]

PMID: 32016379

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Project description:IntroductionVancomycin (VAN) failures associated with the treatment of complicated methicillin-resistant Staphylococcus aureus (MRSA) infections have been well described. The reported "seesaw effect" demonstrates improved β-lactam activity when VAN and/or daptomycin (DAP) susceptibility decreases. However, there are minimal data comparing ceftaroline (CPT) susceptibility with these agents or teicoplanin (TEI). Therefore, to further explore the seesaw effect, we evaluated the relationship between CPT and VAN, TEI, and DAP susceptibilities.MethodsOne hundred and fifty clinical MRSA isolates from the Anti-Infective Research Laboratory (Detroit, MI, USA) from 2008 to 2012 were analyzed. VAN, TEI, DAP and CPT minimum inhibitory concentrations (MIC) were determined via Etest methodology. MIC50 and MIC90 were calculated for each antibiotic. Additionally, four isogenic strain pairs were randomly selected for evaluation by time-kill methodology for the potential of enhanced killing by CPT as MICs increased to VAN, TEI, and DAP.ResultsCPT MICs were inversely correlated with VAN, DAP, and TEI MICs with correlation coefficients of -0.535, -0.483, and -0.386, respectively (P ≤ 0.05). Comparison of the MIC relationship for glycopeptides and lipopeptides resulted in a positive correlation for all agent combinations. In time-kill evaluations, CPT demonstrated greater reductions in log10 colony-forming unit (CFU)/mL against mutant strains (3.73 ± 0.67) versus parents (2.79 ± 0.75) despite no change in CPT MIC (P = 0.112).ConclusionThis study demonstrated a marked "seesaw effect" whereby CPT displayed increased susceptibility as the VAN, DAP, and TEI MICs increased. Additionally, we observed a positive linear correlation between VAN, DAP, and TEI MICs for all agent combinations. Enhanced activity was noted with CPT in mutant strains versus the parent strains despite no change in MIC. Based upon the enhanced CPT activity observed against strains with decreased susceptibility to VAN, DAP and TEI, CPT may provide an option for infections with reduced susceptibility to glycopeptides or lipopeptides. Further evaluation is warranted to investigate the clinical implications of the seesaw effect.