Wyniki wyszukiwania - Biblioteka Nauki

1

Staphylococcus aureus as an infectious agent: overview of biochemistry and molecular genetics of its pathogenicity

100%

Plata K. , Rosato A. , Węgrzyn G.

Acta Biochimica Polonica

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2009

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tom 56

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nr 4

597-612

EN

Although it is estimated that 20-30% of the general human population are carriers of Staphylococcus aureus, this bacterium is one of the most important etiological agents responsible for healthcare-associated infections. The appearance of methicillin resistant S. aureus (MRSA) strains has created serious therapeutical problems. Detailed understanding of the mechanisms of S. aureus infections seems necessary to develop new effective therapies against this pathogen. In this article, we present an overview of the biochemical and genetic mechanisms of pathogenicity of S. aureus strains. Virulence factors, organization of the genome and regulation of expression of genes involved in virulence, and mechanisms leading to methicilin resistance are presented and briefly discussed.

2

Drug resistance profile and detection of genes responsible for methicillin resistance in Staphylococcus aureus isolated from municipal waste

100%

Wolny-Koładka K.

Journal of Water and Land Development

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2023

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tom no. 56

136--141

EN

Currently, we are facing the ever-increasing phenomenon of bacteria being resistant to antibiotics. It is the consequence of excessive and incorrect use of drugs. The phenomenon is a global problem affecting bacteria both in their hospital population and in the natural environment. Municipal waste is an environment conducive to the development of microorganisms, therefore it contains various groups of bacteria, including drug-resistant staphylococci. The aim of the study was to identify species of bacteria, determine their antibiotic resistance, and assess the occurrence of genes responsible for methicillin resistance in Staphylococcus aureus isolated from mixed municipal waste. Strains were isolated by Koch’s serial dilution method with the use of microbiological media. Species were identified using the MALDI TOF-MS technique, whereas the drug resistance profile was determined by disk diffusion and molecular PCR methods. 250 isolates of S. aureus were collected. The highest resistance found was to cefoxitin, erythromycin and tetracycline. Among the bacteria collected, resistance to 1, 2, 3 or 4 antibiotics at the same time was the most common, with a maximum of 10. Additionally, 45 (18%) MDR (multidrug-resistant) isolates were detected. Methicillin resistance was found by the disk diffusion test in 60 (24%) strains, while the mecA gene was detected in as many as 180 (72%) isolates.

3

Molecular docking and pharmacokinetic prediction of phytochemicals from Syzygium cumini in interaction with penicillin-binding protein 2a and erythromycin ribosomal methylase of Staphylococcus aureus

72%

Shidiki A. , Vyas A.

BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology

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2022

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tom 103

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nr 1

4

Evaluation of a rapid culture-based screening test for detection of methicillin resistant Staphylococcus aureus

72%

Fwity B. , Lobmann R. , Ambrosch A.

Polish Journal of Microbiology

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2011

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tom 60

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nr 3

EN

The performance of a culture based assay, BacLite™ Rapid MRSA for the rapid detection (5 hours) of methicillin resistant Staphylococcus aureus (MRSA) from specimens (n = 377) obtained from nares, throat, wounds and perineum was investigated. Compared to culture based reference methods (chromogenic MRSA ID (bioMerieux)), selective enrichment broth, PBP2’ latex agglutination (Oxoid) and VITEK 2 identification (bioMerieux), an overall sensitivity of 71% with a 82% specificity and a negative predictive value (NPV) of 95% was provided. The Baclite™ test is rapid and easy to use and has the advantage of a culture-based detection method for MRSA.

5

Lack of correlation between X region spa polymorphism and virulence of methicillin resistant and methicillin sensitive Staphylococcus aureus strains

72%

Kurlenda J. , Grinholc M. , Szweda P.

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tom 57

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nr 1

135-138

EN

Staphylococcus aureus is an etiological factor of severe infections in both hospital and ambulatory environments. As methicillin resistant Staphylococcus aureus strains spread quickly across healthcare centers resulting in life-threatening infections with increased mortality, they are considered more virulent than MSSA strains. Protein A, encoded by the spa gene, is one of the virulence factors involved in the staphylococcal pathogenesis. It has been suggested that the number of 24-bp tandem repeat units along the X region of the spa gene correlates with the virulence level of the strains. The current work analyzed the relationships between the virulence of MRSA and MSSA strains with region X polymorphism. No obvious correlation was observed.

6

Multiple-locus variable number of tandem repeats fingerprinting (MLVF) and virulence factor analysis of methicillin resistant Staphylococcus aureus SCCmec type III

72%

Emaneini M. , Jabalameli L. , Iman-Eini H. , Aligholi M. , Ghasemi A. , Nakhjavani F. A. , Taherikalani M. , Khoramian B. , Asadollahi P. , Jabalameli F.

Polish Journal of Microbiology

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2011

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tom 60

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nr 4

EN

Methicillin resistant Staphylococcus aureus (MRSA), particularly strains with type III staphylococcal cassette chromosome mec (SCCmec), represent a serious human pathogen in Tehran, Iran. The disease-causing capability depends on their ability to produce a wide variety of virulent factors. The prevalence of exotoxin genes and multiple-locus variable number of tandem repeats fingerprinting (MLVF) profile among MRSA isolates, from patients in Tehran, was evaluated by PCR and Multiplex-PCR. The MLVF typing of 144 MRSA isolates with type III SCCmec produced 5 different MLVF types. Generally, 97.2% (140/144) of all the isolates were positive for at least one of the tested exotoxin genes. The most prevalent genes were hld, found in 87.5% (126/144) of the isolates followed by lukE-lukD and hla found in 72.9% (105/144) and 70.1% (101/144) of the isolates, respectively. The tst gene, belonging to MLVF types I, IV and V, was found among three of the isolates from blood and wound samples. The sea gene was detected in 58.3% (84/144) of the isolates and the sed and see genes were found in one isolate with MLVF type V. The coexistence of genes was observed in the 87.5% (126/144) of the isolates.The rate of coexistence of hld with lukE-lukD, hla with lukE-lukD and sea with lukE-lukD were 66.7% (96/144), 44.4% (64/144) and 44.4% (64/144), respectively. The present study demonstrated that MRSA strains with type III SCCmec show different MLVF patterns and exotoxin profiles.

7

Species-specific sensitivity of coagulase-negative staphylococci to single antibiotics and their combinations

72%

Szymanska G. , Szemraj M. , Szewczyk E. M.

Polish Journal of Microbiology

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2011

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tom 60

|

nr 2

EN

The activity of β-lactam antibiotics (oxacillin, cloxacillin, cephalotin), vancomycin, gentamicin and rifampicin applied in vitro individually and in combination against 37 nosocomial methicillin-resistant strains of coagulase-negative staphylococci (CNS) was assessed to demonstrate the heterogeneity of this group of bacteria and estimate the chance of the efficacy of such therapy. The strains belonged to four species: Staphylococcus epidermidis, Staphylococcus haemolyticus, Staphylococcus cohnii, Staphylococcus hominis. They originated from a hospital environment and from the skin of medical staff of the intensive care unit of a paediatric ward at a university hospital. All strains were methicillin-resistant, according to CLSI standards, but individual strains differed in MICOX values. Susceptibility to other tested antibiotics was also characteristic for the species. The increased susceptibility to antibiotics in combinations, tested by calculating the fractional inhibitory concentration (FIC) index, concerned 26 out of 37 investigated strains and it was a feature of a particular species. Combinations of vancomycin and cephalotin against S. epidermidis and oxacillin with vancomycin were significant, as well as cephalotin and rifampicin in growth inhibition of multiresistant S. haemolyticus strains.

8

Detection of methicillin resistance in hospital environmental strains of coagulase-negative staphylococci

72%

Nowak T. , Balcerczak E. , Mirowski M. , Szewczyk E. M.

Polish Journal of Microbiology

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2006

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tom 55

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nr 4

EN

The aim of this study was to evaluate methicillin resistance detection methods currently used when studying coagulase-negative staphylococci (CoNS). The resistance to oxacillin of 142 strains from seven species of CoNS isolated from the Intensive Care Unit environments was tested. The methods used were: disc diffusion test with cefoxitin (FOX₃₀) and oxacillin (OX₁), oxacillin agar screen test with 6 mg/l of oxacillin (MHOXA), latex test for PBP2a (LA) and detection of mecA via PCR. One hundred and one isolates were methicillin-resistant in at least one of methods used, but only 74 were mecA -positive. Of the 68 mecX-negative strains: two were positive by OX₁, the LA and MHOXA methods; three by the LA and MHOXA; and 22 only by OX₁, test. Most of these strains were from the novobiocin-resistant CoNS group. The results obtained for all tested strains using FOX₃₀ showed complete concordance with the presence of the mecA gene.

9

Photodynamic effect of protoporphyrin diarginate [PPArg2] on methicillin-resistant Staphylococcus aureus and human dermal fibroblasts

72%

Grinholc M. , Kawiak A. , Kurlenda J. , Graczyk A. , Bielawski K. P.

Acta Biochimica Polonica

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2008

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tom 55

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nr 1

EN

The worldwide rise in the antibiotic resistance of bacteria forces the development of alternative antimicrobial treatments. A potential approach is photodynamic inactivation (PDI). The aim of the present study was to determine the phototoxicity of protoporphyrin diarginate (PPArg2) against methicillin-resistant Staphylococcus aureus and human dermal fibroblasts. Different concentrations (0 to 20 µM) of PPArg2 and light dose of 6 J cm -2 were tested. Cell viability was evaluated using the methylthiazoletetrazolium (MTT) assay. Incubation with 10 µM followed by illumination yielded a 3.6 log10-unit reduction in the viable count for Staphylococcus aureus. At the same experimental conditions, only 22.5% of the fibroblasts were photoinactivated. Protoporphyrin diarginate at concentrations up to 20 µM demonstrated no toxicity towards S. aureus or fibroblasts when not irradiated. These results suggest that the protoporphyrin diarginate exerts a high bactericidal effect against methicillin-resistant S. aureus strain without harming eukaryotic cells.

10

Staphylococcus aureus as an infectious agent: overview of biochemistry and molecular genetics of its pathogenicity

58%

Plata K. , Rosato A. E. , Wegrzyn G.

Acta Biochimica Polonica

|

2009

|

tom 56

|

nr 4

597-612

EN

Although it is estimated that 20-30% of the general human population are carriers of Staphylococcus aureus, this bacterium is one of the most important etiological agents responsible for healthcare-associated infections. The appearance of methicillin resistant S. aureus (MRSA) strains has created serious therapeutical problems. Detailed understanding of the mechanisms of S. aureus infections seems necessary to develop new effective therapies against this pathogen. In this article, we present an overview of the biochemical and genetic mechanisms of pathogenicity of S. aureus strains. Virulence factors, organization of the genome and regulation of expression of genes involved in virulence, and mechanisms leading to methicilin resistance are presented and briefly discussed.