scholarly journals Rotating Magnetic Field Increases β-Lactam Antibiotic Susceptibility of Methicillin-Resistant Staphylococcus aureus Strains

2021 ◽  
Vol 22 (22) ◽  
pp. 12397
Author(s):  
Marta Woroszyło ◽  
Daria Ciecholewska-Juśko ◽  
Adam Junka ◽  
Radosław Drozd ◽  
Marcin Wardach ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Staphylococcus Aureus ◽  
Cell Walls ◽  
Intact Cell ◽  
Rotating Magnetic Field ◽  
Developmental Potential ◽  
Methicillin Resistant ◽  
Morphological Alterations ◽  
Minimal Inhibitory Concentrations ◽  
The Impact

Methicillin-resistant strains of Staphylococcus aureus (MRSA) have developed resistance to most β-lactam antibiotics and have become a global health issue. In this work, we analyzed the impact of a rotating magnetic field (RMF) of well-defined and strictly controlled characteristics coupled with β-lactam antibiotics against a total of 28 methicillin-resistant and sensitive S. aureus strains. The results indicate that the application of RMF combined with β-lactam antibiotics correlated with favorable changes in growth inhibition zones or in minimal inhibitory concentrations of the antibiotics compared to controls unexposed to RMF. Fluorescence microscopy indicated a drop in the relative number of cells with intact cell walls after exposure to RMF. These findings were additionally supported by the use of SEM and TEM microscopy, which revealed morphological alterations of RMF-exposed cells manifested by change of shape, drop in cell wall density and cytoplasm condensation. The obtained results indicate that the originally limited impact of β-lactam antibiotics in MRSA is boosted by the disturbances caused by RMF in the bacterial cell walls. Taking into account the high clinical need for new therapeutic options, effective against MRSA, the data presented in this study have high developmental potential and could serve as a basis for new treatment options for MRSA infections.

The Analysis of the Impact of a Mild, Low-iodine, Lotion Soap on the Reduction of Nosocomial Methicillin-Resistant Staphylococcus aureus: A New Opportunity for Surveillance by Objectives

1987 ◽  
Vol 8 (7) ◽  
pp. 284-288 ◽  
Author(s):  
Kim M. Onesko ◽  
Eugene C. Wienke
Keyword(s):  
Staphylococcus Aureus ◽  
Nosocomial Infections ◽  
Control Measures ◽  
Methicillin Resistant ◽  
Care Community ◽  
Infection Control Measures ◽  
Medical Division ◽  
Tract Infections ◽  
The Impact ◽  
Community Teaching

AbstractA significant unremitting increase in the incidence of nosocomial methicillin-resistant Staphylococcus aureus (MRSA) infections in a 500-bed acute care community teaching hospital prompted reevaluation of the efficacy of the infection control measures used. A well-accepted, low-iodine, antimicrobial soap was used to replace a liquid natural handsoap in two areas with the highest incidence of MRSA—the intensive care unit, and a medical division.Over a two-year period, an analysis was made of the effect of soap replacement on nosocomial infections and pathogens. Soap changeover occurred at the midpoint of the two-year period. From year to year, the nosocomial MRSA rate decreased 80% (t test, P=0.005). Other pathogens that demonstrated a dramatic decrease included methicillin-sensitive Staphylococcus aureus (MSSA), infections where no pathogens were isolated, and various gram-negative infections. Categories of nosocomial infections that decreased included surgical wound infections, primary bacteremias, and respiratory tract infections. The overall nosocomial infection rate of the two combined areas decreased 21.5%, representing a year-to-year savings of $109,500. As a result, the decision was made to install the low-iodine hand-soap permanently at all sinks within the hospital.

scholarly journals Linezolid Attenuates Lethal Lung Damage during Postinfluenza Methicillin-Resistant Staphylococcus aureus Pneumonia

2019 ◽  
Vol 87 (10) ◽  
Author(s):  
Atul K. Verma ◽  
Christopher Bauer ◽  
Vijaya Kumar Yajjala ◽  
Shruti Bansal ◽  
Keer Sun
Keyword(s):  
Staphylococcus Aureus ◽  
Therapeutic Effect ◽  
Critical Role ◽  
Lung Damage ◽  
Alpha Toxin ◽  
Methicillin Resistant ◽  
Content Type ◽  
Linezolid Therapy ◽  
Staphylococcus Aureus Pneumonia ◽  
The Impact

ABSTRACT Postinfluenza methicillin-resistant Staphylococcus aureus (MRSA) infection can quickly develop into severe, necrotizing pneumonia, causing over 50% mortality despite antibiotic treatments. In this study, we investigated the efficacy of antibiotic therapies and the impact of S. aureus alpha-toxin in a model of lethal influenza virus and MRSA coinfection. We demonstrate that antibiotics primarily attenuate alpha-toxin-induced acute lethality, even though both alpha-toxin-dependent and -independent mechanisms significantly contribute to animal mortality after coinfection. Furthermore, we found that the protein synthesis-suppressing antibiotic linezolid has an advantageous therapeutic effect on alpha-toxin-induced lung damage, as measured by protein leak and lactate dehydrogenase (LDH) activity. Importantly, using a Panton-Valentine leucocidin (PVL)-negative MRSA isolate from patient sputum, we show that linezolid therapy significantly improves animal survival from postinfluenza MRSA pneumonia compared with vancomycin treatment. Rather than improved viral or bacterial control, this advantageous therapeutic effect is associated with a significantly attenuated proinflammatory cytokine response and acute lung damage in linezolid-treated mice. Together, our findings not only establish a critical role of alpha-toxin in the extreme mortality of secondary MRSA pneumonia after influenza but also provide support for the possibility that linezolid could be a more effective treatment than vancomycin to improve disease outcomes.

Risk Factors for Methicillin-Resistant Staphylococcus aureus (MRSA) Acquisition in Roommate Contacts of Patients Colonized or Infected With MRSA in an Acute-Care Hospital

2008 ◽  
Vol 29 (7) ◽  
pp. 600-606 ◽  
Author(s):  
Christine Moore ◽  
Jastej Dhaliwal ◽  
Agnes Tong ◽  
Sarah Eden ◽  
Cindi Wigston ◽  
...  
Keyword(s):  
Risk Factors ◽  
Staphylococcus Aureus ◽  
Acute Care ◽  
Significant Risk ◽  
Acute Care Hospital ◽  
Skin Lesions ◽  
Care Hospital ◽  
Methicillin Resistant ◽  
The Impact

Objective.To identify risk factors for acquisition of methicillin-resistant Staphylococcus aureus (MRSA) in patients exposed to an MRSA-colonized roommate.Design.Retrospective cohort study.Setting.A 472-bed acute-care teaching hospital in Toronto, Canada.Patients.Inpatients who shared a room between 1996 and 2004 with a patient who had unrecognized MRSA colonization.Methods.Exposed roommates were identified from infection-control logs and from results of screening for MRSA in the microbiology database. Completed follow-up was defined as completion of at least 2 sets of screening cultures (swab samples from the nares, the rectum, and skin lesions), with at least 1 set of samples obtained 7–10 days after the last exposure. Chart reviews were performed to compare those who did and did not become colonized with MRSA.Results.Of 326 roommates, 198 (61.7%) had completed follow-up, and 25 (12.6%) acquired MRSA by day 7–10 after exposure was recognized, all with strains indistinguishable by pulsed-field gel electrophoresis from those of their roommate. Two (2%) of 101 patients were not colonized at day 7–10 but, with subsequent testing, were identified as being colonized with the same strain as their roommate (one at day 16 and one at day 18 after exposure). A history of alcohol abuse (odds ratio [OR], 9.8 [95% confidence limits {CLs}, 1.8, 53]), exposure to a patient with nosocomially acquired MRSA (OR, 20 [95% CLs, 2.4,171]), increasing care dependency (OR per activity of daily living, 1.7 [95% CLs, 1.1, 2.7]), and having received levofloxacin (OR, 3.6 [95% CLs, 1.1,12]) were associated with MRSA acquisition.Conclusions.Roommates of patients with MRSA are at significant risk for becoming colonized. Further study is needed of the impact of hospital antimicrobial formulary decisions on the risk of acquisition of MRSA.

scholarly journals Introduction of the mec Element (Methicillin Resistance) into Staphylococcus aureus Alters In Vitro Functional Activities of Fibrinogen and Fibronectin Adhesins

1998 ◽  
Vol 42 (3) ◽  
pp. 564-570 ◽  
Author(s):  
Pierre E. Vaudaux ◽  
Vincenza Monzillo ◽  
Patrice Francois ◽  
Daniel P. Lew ◽  
Tim J. Foster ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistance ◽  
Bacterial Colonization ◽  
Protein A ◽  
Methicillin Resistant ◽  
Functional Activities ◽  
Extracellular Matrix Components ◽  
Resistant Strains ◽  
The Impact

ABSTRACT Some methicillin-resistant strains of Staphylococcus aureus are defective in the production of major surface components such as protein A, clumping factor, or other important adhesins to extracellular matrix components which may play a role in bacterial colonization and infection. To evaluate the impact of methicillin resistance (mec) determinants on bacterial adhesion mediated by fibrinogen or fibronectin adhesins, we compared the in vitro attachment of two genetically distinct susceptible strains (NCTC8325 and Newman) to protein-coated surfaces with that of isogenic methicillin-resistant derivatives. All strains containing an intactmec element in their chromosomes were found to be defective in adhesion to fibrinogen and fibronectin immobilized on polymethylmethacrylate coverslips, regardless of the presence or absence of additional mutations in the femA,femB, or femC gene, known to decrease expression of methicillin resistance in S. aureus. Western ligand affinity blotting or immunoblotting of cell wall-associated adhesins revealed similar contents of fibrinogen- or fibronectin-binding proteins in methicillin-resistant strains compared to those of their methicillin-susceptible counterparts. In contrast to methicillin-resistant strains carrying a mec element in their genomes, methicillin-resistant strains constructed in vitro, by introducing the mecA gene on a plasmid, retained their adhesion phenotypes. In conclusion, the chromosomal insertion of themec element into genetically defined strains of S. aureus impairs the in vitro functional activities of fibrinogen or fibronectin adhesins without altering their production. This effect is unrelated to the activity of the mecA gene.

Colonization With Methicillin-Resistant Staphylococcus aureus in ICU Patients Morbidity, Mortality, and Glycopeptide Use

2001 ◽  
Vol 22 (11) ◽  
pp. 687-692 ◽  
Author(s):  
Maité Garrouste-Orgeas ◽  
Jean-Francois Timsit ◽  
Hatem Kallel ◽  
Adel Ben Ali ◽  
Marie Francoise Dumay ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Tertiary Care ◽  
Icu Mortality ◽  
Icu Patients ◽  
Methicillin Resistant ◽  
Saps Ii ◽  
Icu Stay ◽  
Mrsa Infection ◽  
The Impact ◽  
Mrsa Colonization

Abstract Objective: To determine the impact of methicillin-resis-tant Staphylococcus aureus (MRSA) colonization on the occurrence of S aureus infections (methicillin-resistant and methicillin-suscep-tible), the use of glycopeptides, and outcome among intensive care unit (ICU) patients. Design: Prospective observational cohort survey. Setting: A medical-surgical ICU with 10 single-bed rooms in a 460-bed, tertiary-care, university-affiliated hospital. Patients: A total of 1,044 ICU patients were followed for the detection of MRSA colonization from July 1, 1995, to July, 1 1998. Methods: MRSA colonization was detected using nasal samples in all patients plus wound samples in surgical patients within 48 hours of admission or within the first 48 hours of ICU stay and weekly thereafter. MRSA infections were defined using Centers for Disease Control and Prevention standard definitions, except for ventilator-associated pneumonia and catheter-related infections, which were defined by quantitative distal culture samples. Results: One thousand forty-four patients (70% medical patients) were included in the analysis. Mean age was 61±18 years; mean Simplified Acute Physiologic Score (SAPS) II was 36.4±20; and median ICU stay was 4 (range, 1-193) days. Two hundred thirty-one patients (22%) died in the ICU. Fifty-four patients (5.1%) were colonized with MRSA on admission, and 52 (4.9%) of 1,044 acquired MRSA colonization in the ICU. Thirty-five patients developed a total of 42 S aureus infections (32 MRSA, 10 methi-cillin-susceptible). After factors associated with the development of an S aureus infection were adjusted for in a multivariate Cox model (SAPS II >36: hazard ratio [HR], 1.64; P=.09; male gender: HR, 2.2; P=.05), MRSA colonization increased the risk of S aureus infection (HR, 3.84; P=.0003). MRSA colonization did not influence ICU mortality (HR, 1.01; P=.94). Glycopeptides were used in 11.4% of the patients (119/1,044) for a median duration of 5 days. For patients with no colonization, MRSA colonization on admission, and ICU-acquired MRSA colonization, respectively, glycopeptide use per 1,000 hospital days was 37.7, 235.2, and 118.3 days. MRSA colonization per se increased by 3.3-fold the use of glycopeptides in MRSA-colonized patients, even when an MRSA infection was not demonstrated, compared to non-colonized patients. Conclusions: In our unit, MRSA colonization greatly increased the risk of S aureus infection and of glycopeptide use in colonized and non-colonized patients, without influencing ICU mortality. MRSA colonization influenced glycopeptide use even if an MRSA infection was not demonstrated; thus, an MRSA control program is warranted to decrease vancomycin use and to limit glycopeptide resistance in gram-positive cocci.

Flow Control during Solidification of AlSi-Alloys by Means of Tailored AC Magnetic Fields and the Impact on the Mechanical Properties

2014 ◽  
Vol 790-791 ◽  
pp. 384-389
Author(s):  
Dirk Räbiger ◽  
Bernd Willers ◽  
Sven Eckert
Keyword(s):  
Magnetic Field ◽  
Mechanical Properties ◽  
Grain Size ◽  
Magnetic Fields ◽  
Flow Field ◽  
Phase Distribution ◽  
Solidification Process ◽  
Quantitative Information ◽  
Rotating Magnetic Field ◽  
The Impact

This paper presents an experimental study which in a first stage is focused on obtaining quantitative information about the isothermal flow field exposed to various magnetic field configurations. Melt stirring has been realized by utilizing a rotating magnetic field. In a second step directional solidification of AlSi7 alloys from a water-cooled copper chill was carried out to verifythe effect of a certain flow field on the solidification process and on the resulting mechanical properties. The solidified structure was reviewed in comparison to an unaffected solidified ingot. Measurements of the phase distribution, the grain size, the hardness and the tensile strength were realized. Our results demonstrate the potential of magnetic fields to control the grain size, the formation of segregation freckles and the mechanical properties. In particular, time–modulated rotating fields show their capability to homogenize both the grain size distribution and the corresponding mechanical properties.

scholarly journals Modulation of Fibronectin Adhesins and Other Virulence Factors in a Teicoplanin-Resistant Derivative of Methicillin-Resistant Staphylococcus aureus

2004 ◽  
Vol 48 (8) ◽  
pp. 2958-2965 ◽  
Author(s):  
Adriana Renzoni ◽  
Patrice Francois ◽  
Dongmei Li ◽  
William L. Kelley ◽  
Daniel P. Lew ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Steady State ◽  
Resistant Strain ◽  
Mrna Levels ◽  
Glycopeptide Resistance ◽  
Methicillin Resistant ◽  
Qrt Pcr ◽  
Sigma B ◽  
Steady State Levels ◽  
The Impact

ABSTRACT The impact of glycopeptide resistance on the molecular regulation of Staphylococcus aureus virulence and attachment to host tissues is poorly documented. We compared stable teicoplanin-resistant methicillin-resistant S. aureus (MRSA) strain 14-4 with its teicoplanin-susceptible MRSA parent, strain MRGR3, which exhibits a high degree of virulence in a rat model of chronic foreign body MRSA infection. The levels of fibronectin-mediated adhesion and surface display of fibronectin-binding proteins were higher in teicoplanin-resistant strain 14-4 than in its teicoplanin-susceptible parent or a teicoplanin-susceptible revertant (strain 14-4rev) that spontaneously emerged during tissue cage infection. Quantitative reverse transcription-PCR (qRT-PCR) showed four- and twofold higher steady-state levels of fnbA and fnbB transcripts, respectively, in strain 14-4 than in its teicoplanin-susceptible counterparts. Analysis of global regulatory activities by qRT-PCR revealed a strong reduction in the steady-state levels of RNAIII and RNAII in the teicoplanin-resistant strain compared to in its teicoplanin-susceptible counterparts. In contrast, sarA mRNA levels were more than fivefold higher in strain 14-4 than in MRGR3 and 14-4rev. Furthermore, the alternative transcription factor sigma B had a higher level of functional activity in the teicoplanin-resistant strain than in its teicoplanin-susceptible counterparts, as evidenced by significant increases in both the sigma B-dependent asp23 mRNA levels and the sarA P3 promoter-derived transcript levels, as assayed by qRT-PCR and Northern blotting, respectively. These data provide further evidence that the emergence of glycopeptide resistance is linked by still poorly understood molecular pathways with significant pleiotropic changes in the expression and regulation of some major virulence genes. These molecular and phenotypic changes may have a profound impact on the bacterial adhesion and colonization properties of such multiresistant organisms.

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