Dataset Information

Increased drug resistance of meticillin-resistant Staphylococcus aureus biofilms formed on a mouse dermal chip model.

ABSTRACT:

Purpose

Meticillin-resistant Staphylococcus aureus (MRSA) biofilm formation in humans is of serious clinical concern. Previous in vitro studies have been performed with biofilms grown only on inorganic substrates; therefore, we investigated the vancomycin (VCM) resistance of MRSA biofilms grown on skin tissue.

Methodology

We established a novel tissue substrate model, namely MRSA grown on segments of mouse skin tissue (dermal chips, DCs), and compared its resistance capacity against VCM with that of MRSA biofilms grown on plastic chips (PCs).Results/Key findings. For one MRSA isolate, we found that the VCM MIC was identical (1.56?µg ml-1) for planktonic cultures and for biofilms-formed on PCs (PC-BF), although the minimum bactericidal concentration (MBC) increased to 6.25?µg ml-1 in PC-BF. On the contrary, the MIC and MBC for biofilms formed on DCs (DC-BF) significantly increased (25 and 50?µg ml-1, respectively). Furthermore, the minimum biofilm-eradicating concentration was higher for DC-BF (100?µg ml-1) than for PC-BF (25?µg ml-1). Using six MRSA strains, we found that in PC-BF, the c.f.u. number decreased with increasing VCM concentration, whereas in DC-BF, it greatly increased until the MIC was reached, accompanied by the formation of large colonies, thicker bacterial walls and the presence of many mitotic cells.

Conclusion

Our results indicate that the VCM resistance of MRSA was greater in DC-BF. We conclude that DCs may provide a specific environment for MRSA that enhances bacterial growth under cytotoxic VCM concentrations, and might be useful for the study of skin wound infections and the effects of antimicrobial drugs.

SUBMITTER: Jimi S

PROVIDER: S-EPMC5817199 | biostudies-literature | 2017 Apr

REPOSITORIES: biostudies-literature

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Publications

Increased drug resistance of meticillin-resistant Staphylococcus aureus biofilms formed on a mouse dermal chip model.

Jimi Shiro S Miyazaki Motoyasu M Takata Tohru T Ohjimi Hiroyuki H Akita Sadanori S Hara Shuuji S

Journal of medical microbiology 20170401 4

<h4>Purpose</h4>Meticillin-resistant Staphylococcus aureus (MRSA) biofilm formation in humans is of serious clinical concern. Previous in vitro studies have been performed with biofilms grown only on inorganic substrates; therefore, we investigated the vancomycin (VCM) resistance of MRSA biofilms grown on skin tissue.<h4>Methodology</h4>We established a novel tissue substrate model, namely MRSA grown on segments of mouse skin tissue (dermal chips, DCs), and compared its resistance capacity again ...[more]

PMID: 28463660

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Project description:BackgroundMethicillin-resistant Staphylococcus aureus (MRSA), a leading cause of chronic infections, forms prolific biofilms which afford an escape route from antibiotic treatment and host immunity. However, MRSA clones are genetically diverse, and mechanisms underlying biofilm formation remain under-studied. Such studies form the basis for developing targeted therapeutics. Here, we studied the temporal changes in the biofilm transcriptome of three pandemic MRSA clones: USA300, HEMRSA-15, and ST239.MethodsBiofilm formation was assessed using a static model with one representative strain per clone. Total RNA was extracted from biofilm and planktonic cultures after 24, 48, and 72 h of growth, followed by rRNA depletion and sequencing (Illumina Inc., San Diego, CA, United States, NextSeq500, v2, 1 × 75 bp). Differentially expressed gene (DEG) analysis between phenotypes and among early (24 h), intermediate (48 h), and late (72 h) stages of biofilms was performed together with in silico co-expression network construction and compared between clones. To understand the influence of SCCmec and ACME on biofilm formation, isogenic mutants containing deletions of the entire elements or of single genes therein were constructed in USA300.ResultsGenes involved in primarily core genome-encoded KEGG pathways (transporters and others) were upregulated in 24-h biofilm culture compared to 24-h planktonic culture. However, the number of affected pathways in the ST239 24 h biofilm (n = 11) was remarkably lower than that in USA300/EMRSA-15 biofilms (USA300: n = 27, HEMRSA-15: n = 58). The clfA gene, which encodes clumping factor A, was the single common DEG identified across the three clones in 24-h biofilm culture (2.2- to 2.66-fold). In intermediate (48 h) and late (72 h) stages of biofilms, decreased expression of central metabolic and fermentative pathways (glycolysis/gluconeogenesis, fatty acid biosynthesis), indicating a shift to anaerobic conditions, was already evident in USA300 and HEMRSA-15 in 48-h biofilm cultures; ST239 showed a similar profile at 72 h. Last, SCCmec+ACME deletion and opp3D disruption negatively affected USA300 biofilm formation.ConclusionOur data show striking differences in gene expression during biofilm formation by three of the most important pandemic MRSA clones, USA300, HEMRSA-15, and ST239. The clfA gene was the only significantly upregulated gene across all three strains in 24-h biofilm cultures and exemplifies an important target to disrupt early biofilms. Furthermore, our data indicate a critical role for arginine catabolism pathways in early biofilm formation.

Project description:The role of general practitioners (GPs) as reservoir and potential source for Staphylococcus aureus (SA) transmission is unknown. Our primary objective was to evaluate the prevalence of SA and community-acquired methicillin resistant SA (CA-MRSA) carrier status (including spa typing) among GPs and their patients in Belgium. The secondary objective was to determine the association between SA/CA-MRSA carriage in patients and their characteristics, SA carriage in GPs, GP and practice characteristics.The Belgian GPs, who swabbed their patients in the APRES study (which assessed the prevalence of SA nasal carriage in nine European countries; November 2010 -June 2011), were asked to swab themselves as well (May-June 2011). GPs and their patients had to complete a questionnaire on factors related to SA carriage and transmission. SA isolation including CA-MRSA and spa typing was performed on the swabs.In eighteen practices 34 GPs swabbed patients of which 25 GPs provided personal swabs. The analysis was performed on 3008 patient records. Among GPs SA carriage (28%) was more prevalent than among their patients (19.2%), but CA-MRSA carriage was not present. SA was more prevalent among younger patients and those living with cattle. Spa typing SA and MRSA strains did not suggest correlation within practices or between patients and GPs, but chronic skin conditions of GPs and always handshaking patients by SA positive GPs were associated with more SA among patients, and hand washing after every patient contact with less SA among patients in practices with high antibiotic prescribing rates.No MRSA was found among GPs, although their SA carriership was higher compared to their patients'. Spa types did not cluster within practices, possibly due to difference in timing of swabbing. To minimise SA transmission to their patients GPs should consider taking appropriate care of their chronic skin diseases, antibiotic prescribing behaviour, handshaking and hand washing habits.

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.

Dataset Information

Increased drug resistance of meticillin-resistant Staphylococcus aureus biofilms formed on a mouse dermal chip model.

Purpose

Methodology

Conclusion

Publications

Increased drug resistance of meticillin-resistant Staphylococcus aureus biofilms formed on a mouse dermal chip model.

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