Molecular Features of Virulence and Resistance Mechanisms in Nosocomial and Community-Acquired Staphylococcus aureus

Gheorghe, Irina; Popa, Marcela; Măruţescu, Luminiţa

doi:10.5772/intechopen.75191

Cited by 7 publications

(10 citation statements)

References 84 publications

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“…The literature shows that combination of QAC with other antimicrobial agents results in improved antimicrobial activity of the drug [ 86 , 87 ]. Furthermore, the lipidic nature of the quatsomes could have enhanced the transport of the drug into the thick peptidoglycan layer of MRSA, thus avoiding ion trapping, which is the main resistance mechanism of MRSA to bare VCM [ 88 , 89 , 90 ], resulting in a lower MIC.…”

Section: Resultsmentioning

confidence: 99%

Formulation of pH-Responsive Quatsomes from Quaternary Bicephalic Surfactants and Cholesterol for Enhanced Delivery of Vancomycin against Methicillin Resistant Staphylococcus aureus

et al. 2020

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Globally, human beings continue to be at high risk of infectious diseases caused by methicillin-resistant Staphylococcus aureus (MRSA); and current treatments are being depleted due to antimicrobial resistance. Therefore, the synthesis and formulation of novel materials is essential for combating antimicrobial resistance. The study aimed to synthesize a quaternary bicephalic surfactant (StBAclm) and thereof to formulate pH-responsive vancomycin (VCM)-loaded quatsomes to enhance the activity of the antibiotic against MRSA. The surfactant structure was confirmed using 1H, 13C nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FT-IR), and high-resolution mass spectrometry (HRMS). The quatsomes were prepared using a sonication/dispersion method and were characterized using various in vitro, in vivo, and in silico techniques. The in vitro cell biocompatibility studies of the surfactant and pH-responsive vancomycin-loaded quatsomes (VCM-StBAclm-Qt1) revealed that they are biosafe. The prepared quatsomes had a mean hydrodynamic diameter (MHD), polydispersity index (PDI), and drug encapsulation efficiency (DEE) of 122.9 ± 3.78 nm, 0.169 ± 0.02 mV, and 52.22 ± 8.4%, respectively, with surface charge switching from negative to positive at pH 7.4 and pH 6.0, respectively. High-resolution transmission electron microscopy (HR-TEM) characterization of the quatsomes showed spherical vesicles with MHD similar to the one obtained from the zeta-sizer. The in vitro drug release of VCM from the quatsomes was faster at pH 6.0 compared to pH 7.4. The minimum inhibitory concentration (MIC) of the drug loaded quatsomes against MRSA was 32-fold and 8-fold lower at pH 6.0 and pH 7.4, respectively, compared to bare VCM, demonstrating the pH-responsiveness of the quatsomes and the enhanced activity of VCM at acidic pH. The drug-loaded quatsomes demonstrated higher electrical conductivity and a decrease in protein and deoxyribonucleic acid (DNA) concentrations as compared to the bare drug. This confirmed greater MRSA membrane damage, compared to treatment with bare VCM. The flow cytometry study showed that the drug-loaded quatsomes had a similar bactericidal killing effect on MRSA despite a lower (8-fold) VCM concentration when compared to the bare VCM. Fluorescence microscopy revealed the ability of the drug-loaded quatsomes to eradicate MRSA biofilms. The in vivo studies in a skin infection mice model showed that groups treated with VCM-loaded quatsomes had a 13-fold decrease in MRSA CFUs when compared to the bare VCM treated groups. This study confirmed the potential of pH-responsive VCM-StBAclm quatsomes as an effective delivery system for targeted delivery and for enhancing the activity of antibiotics.

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Section: Resultsmentioning

confidence: 99%

Formulation of pH-Responsive Quatsomes from Quaternary Bicephalic Surfactants and Cholesterol for Enhanced Delivery of Vancomycin against Methicillin Resistant Staphylococcus aureus

et al. 2020

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“…The majority of the staphylococcal strains produced lecithinase, a factor that contributes to the dissemination of infection, revealing the risk of a severe evolution of an otherwise localized infection. Moreover, the production of lipase translates into the ability to convert local host tissues into nutrients vital for bacterial development and also augments the possibility to penetrate and affect host tissues [ 40 ].…”

Section: Discussionmentioning

confidence: 99%

“…The types and severity of infections are influenced by the soluble factors produced by bacteria. For example, in some studies, the most virulent strains were isolated from blood cultures and peritoneal liquid, while in ocular infections were found bacteria with less virulent factors production [ 40 ].…”

Section: Discussionmentioning

confidence: 99%

Phenotypic and genotypic virulence features of staphylococcal strains isolated from difficult-to-treat skin and soft tissue infections

et al. 2021

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Chronic infections represent an important burden on the healthcare system and have a significant impact on the patients’ quality of life. While Staphylococcus spp. are commensal bacteria, they can become pathogenic, leading to various types of infections. In this study we aimed to characterize the virulence profiles of staphylococcal strains involved in difficult-to-treat skin and soft tissue infections, from both phenotypic and genotypic points of view. Phenotypic ability of the strains to secrete soluble virulence factors was assessed by a culturing dependent assay and their capacity to develop biofilms on inert substrate was screened by an adapted crystal violet microtiter method. We also tested the presence of several virulence genes by PCR. Most of the studied strains were isolated from purulent secretions of acne lesions and frequently secreted two or three soluble virulence factors. Most frequently secreted soluble virulence factors were caseinase (89%), lipase (71%) and lecithinase (67%). Almost half of the strains produced a well-represented biofilm. The molecular characterization showed the presence of the genes cna, hlg, clfA, and clfB. Staphylococcal strains that produce difficult-to-treat skin and soft tissue infections seem to be characterized by an enhanced ability to produce different soluble virulence factors and to develop biofilms in vitro. Further studies need to be developed in other Staphylococcus spp. infections in order to confirm this hypothesis.

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“…Other authors perform a qualitative analysis of apple juices [10,11]. Regarding the chemical composition of apples and their juices, the topic is well developed, for example, such data give [12,13,14,15,16,17,18,19,20,21,22,23,24,25,26] and others.…”

Section: Technological Parametersmentioning

confidence: 99%

Agro-ecological and Technological Quality of Some Apples

Sotirov¹,

Glavev²,

Sotirov³

et al. 2021

Wseas Transactions on Environment and Development

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The aim of the study is to investigate cloudy apple juices, produced from 83 apple varieties, grown by the Institute of Agriculture in town of Kyustendil, Bulgaria for their main ecological and technological parameters, in view of their safety for the population and the possibilities for their use as raw material in the food industry. The study found, that the apples are environmentally friendly for the studied parameters. Technologically, there are varieties with the highest juice yields (over 70%) - Defloga, Ginger Gold, Gold Rush, Granny Smith, and Melrose. The most tasty and colored juices of fresh fruit and fruit flour are separated from the Florina, Free Redstar, Ginger Gold, Gold Rush, Golden Delicious, and Granny Smith. Some practically do not give juice and material for fruit flour with the applied method 100% cold-pressed apple juice, but they produce puree with high quality as the Belgolden, Braeburn, Charden, and Red Delicious. There were observed very stable approximate ratios between Conductivity, Total Dissolved Solids, and Salt content in the juices as follows: Cond./TDS=1.5, TDS/Salt=1.3, Cond./Salt=2. Retio between Total Sugar Content and Total Acidity - Brix/pH = 3-5, as the most tasty and with good color juices have ratio Brix/pH=4.

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Molecular Features of Virulence and Resistance Mechanisms in Nosocomial and Community-Acquired Staphylococcus aureus

Cited by 7 publications

References 84 publications

Formulation of pH-Responsive Quatsomes from Quaternary Bicephalic Surfactants and Cholesterol for Enhanced Delivery of Vancomycin against Methicillin Resistant Staphylococcus aureus

Formulation of pH-Responsive Quatsomes from Quaternary Bicephalic Surfactants and Cholesterol for Enhanced Delivery of Vancomycin against Methicillin Resistant Staphylococcus aureus

Phenotypic and genotypic virulence features of staphylococcal strains isolated from difficult-to-treat skin and soft tissue infections

Agro-ecological and Technological Quality of Some Apples

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