Dataset Information

Association of mprF mutations with cross-resistance to daptomycin and vancomycin in methicillin-resistant Staphylococcus aureus (MRSA).

ABSTRACT: We first reported a phenomenon of cross-resistance to vancomycin (VCM) and daptomycin (DAP) in methicillin-resistant Staphylococcus aureus (MRSA) in 2006, but mechanisms underlying the cross-resistance remain incompletely understood. Here, we present a follow-up study aimed to investigate genetic determinants associated with the cross-resistance. Using 12 sets of paired DAP susceptible (DAP^S) and DAP non-susceptible (DAP^R) MRSA isolates from 12 patients who had DAP therapy, we (i) assessed susceptibility to DAP and VCM, (ii) compared whole-genome sequences, (iii) identified mutations associated with cross-resistance to DAP and VCM, and (iv) investigated the impact of altered gene expression and metabolic pathway relevant to the cross-resistance. We found that all 12 DAP^R strains exhibiting cross-resistance to DAP and VCM carried mutations in mprF, while one DAP^R strain with reduced susceptibility to only DAP carried a lacF mutation. On the other hand, among the 32 vancomycin-intermediate S. aureus (VISA) strains isolated from patients treated with VCM, five out of the 18 strains showing cross-resistance to DAP and VCM carried a mprF mutation, while 14 strains resistant to only VCM had no mprF mutation. Moreover, substitution of mprF in a DAP^S strain with mutated mprF resulted in cross-resistance and vice versa. The elevated lysyl-phosphatidylglycerol (L-PG) production, increased positive bacterial surface charges and activated cell wall (CW) synthetic pathways were commonly found in both clinical isolates and laboratory-developed mutants that carry mprF mutations. We conclude that mprF mutation is responsible for the cross-resistance of MRSA to DAP and VCM, and treatment with DAP is more likely to select for mprF-mediated cross-resistance than is with VCM.

SUBMITTER: Thitiananpakorn K

PROVIDER: S-EPMC7527455 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature

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Association of mprF mutations with cross-resistance to daptomycin and vancomycin in methicillin-resistant Staphylococcus aureus (MRSA).

Thitiananpakorn Kanate K Aiba Yoshifumi Y Tan Xin-Ee XE Watanabe Shinya S Kiga Kotaro K Sato'o Yusuke Y Boonsiri Tanit T Li Feng-Yu FY Sasahara Teppei T Taki Yusuke Y Azam Aa Haeruman AH Zhang Yuancheng Y Cui Longzhu L

Scientific reports 20200930 1

We first reported a phenomenon of cross-resistance to vancomycin (VCM) and daptomycin (DAP) in methicillin-resistant Staphylococcus aureus (MRSA) in 2006, but mechanisms underlying the cross-resistance remain incompletely understood. Here, we present a follow-up study aimed to investigate genetic determinants associated with the cross-resistance. Using 12 sets of paired DAP susceptible (DAP<sup>S</sup>) and DAP non-susceptible (DAP<sup>R</sup>) MRSA isolates from 12 patients who had DAP therapy, ...[more]

PMID: 32999359

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Project description:Although methicillin (meticillin)-resistant Staphylococcus aureus (MRSA) strains with reduced susceptibility to vancomycin (RVS-MRSA; including vancomycin-intermediate S. aureus [VISA] and heterogeneous VISA [hVISA]) have been linked with vancomycin treatment failure, it is unclear whether they are more pathogenic than vancomycin-susceptible MRSA (VS-MRSA). We prospectively assessed patients with clinical MRSA isolates during a 10-month period to determine clinical status (infection versus colonization) and therapeutic outcome before correlating these findings with the results of detailed in vitro assessment of vancomycin susceptibility, including population analysis profile (PAP) testing. hVISA and VISA were defined by standard PAP criteria (area-under-the-curve ratio compared to that of the reference hVISA strain Mu3 [>or=0.9]) and routine CLSI criteria (vancomycin MIC, 4 to 8 microg/ml), respectively. Among the 117 patients assessed, 58 had RVS-MRSA isolates (56 hVISA and 2 VISA) and 59 had VS-MRSA isolates; the patient demographics and comorbidities were similar. RVS-MRSA was associated with a lower rate of infection than VS-MRSA (29/58 versus 46/59; P = 0.003), including a lower rate of bacteremia (3/58 versus 20/59, respectively; P < 0.001). The cure rates in RVS-MRSA and VS-MRSA groups were not statistically different (16/26 versus 31/42; P = 0.43), but the post hoc assessment of treatment regimes and study size made detailed conclusions difficult. The results of the macro method Etest correlated well with the PAP results (sensitivity, 98.3%, and specificity, 91.5%), but broth microdilution and our preliminary RVS-MRSA detection method correlated poorly. All isolates were susceptible to linezolid and daptomycin. These data suggest that detailed prospective laboratory identification of RVS-MRSA isolates may be of limited value and that, instead, such in vitro investigation should be reserved for isolates from patients who are failing appropriate anti-MRSA therapy.

Project description:Elasnin is a recently reported antibiofilm agent that is effective against Gram-positive bacteria including methicillin-resistant Staphylococcus aureus (MRSA). Remarkably, we observed that elasnin has a superior activity in eradicating daptomycin-resistant MRSA strain biofilm, with a lower minimum biofilm eradication concentration (MBEC) value of 0.625 μg/mL, compared to 2.5 μg/mL for the wild type. Confocal microscopy further confirmed the higher biofilm eradication on the daptomycin-resistant strain, displaying ∼53% decrease in cell density upon elasnin treatment, while the wild-type strain was only decreased by ∼15%. Quantitative proteomics revealed that the daptomycin-resistant strain has a lower expression of the membrane, cell wall, and extracellular proteins, and also proteins involved in the arginine biosynthesis, pathogenesis, and cell adhesion compared to the wild type, which may result in weaker biofilm development. This study highlights the potential clinical application of elasnin through its superior biofilm eradication activity against a daptomycin-resistant MRSA strain, and revealed the associated processes governing this superior activity through proteomics analysis. IMPORTANCE Due to the increased use of daptomycin for the treatment of MRSA infections, the emergence of daptomycin-resistant strains has become prevalent in recent years. In this study, we discovered that elasnin, a newly reported antibiofilm compound, has a superior activity in eradicating daptomycin-resistant MRSA strain biofilms compared to the wild type. Follow-up analysis revealed the reason behind this superior activity, which is the lower expression of key proteins that play a role in pathogenesis and cell adhesion in the daptomycin-resistant strain, leading to weaker biofilm development. This showcases the potential use of elasnin in clinical settings where daptomycin-resistant strains and biofilm formation are prevalent. Altogether, our study provides new insights into the mechanism of elasnin in MRSA biofilm cells and identified its superior biofilm eradicating activity in the daptomycin-resistant strain.

Project description:The genomic evolution in vivo in persistent infection was critical information for understanding how methicillin-resistant Staphylococcus aureus (MRSA) was adapted to host environments with high antibiotic selective pressure. Thirty-two successive MRSA blood isolates with incremental non-susceptibility to vancomycin (VISA), daptomycin (DRSA), and/or linezolid (LRSA) were isolated from a patient failing multiple courses of antimicrobial therapy during 1,356 days of bacteremia. Whole genome sequencing (WGS) for all consecutive isolates were conducted to characterize the evolutionary pathways, resistance-associated mutations and their temporal relationship with antimicrobial treatment. The WGS-based phylogeny categorized the isogenic strains into three major clades, I (22 isolates), II (7 isolates), and III (3 isolates), respectively, harboring a median (range) of 7 (1-30), 62 (53-65), and 118 (100-130) non-synonymous mutations when compared to the very first isolate. Clade I strains were further grouped into early and late subclades, which, respectively, shared the most recent common ancestor with Clade III strains at day 393.7 and Clade II strain at day 662.5. Clade I and Clade III strains were characterized, respectively, with high rates of VISA (9/22, 40.9%) and VISA-and-DRSA phenotype (2/3, 66.7%). Linezolid-resistance including VISA-DRSA-and-LRSA phenotype was exclusively identified in Clade II strains after eight courses of linezolid treatment. The LRSA displayed a small colony variant phenotype and were associated with G2576T mutations in domain V region of 23S rRNA. Substantial loss of mobile elements or alleles mediating resistance or virulence were identified during the evolution of multi-resistance. However, the gene loss might not be correlated to the development of VISA, DRSA, or LRSA phenotype. In conclusion, MRSA in persistent bacteremia was adapted to harsh host environment through multiple pathways involving both resistance-associated mutations and extensive gene loss.

Dataset Information

Association of mprF mutations with cross-resistance to daptomycin and vancomycin in methicillin-resistant Staphylococcus aureus (MRSA).

Publications

Association of mprF mutations with cross-resistance to daptomycin and vancomycin in methicillin-resistant Staphylococcus aureus (MRSA).

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