scholarly journals Selection of high-level oxacillin resistance in heteroresistant Staphylococcus aureus by fluoroquinolone exposure

2001 ◽  
Vol 48 (3) ◽  
pp. 375-381 ◽  
Author(s):  
R. A. Venezia
Keyword(s):  
Staphylococcus Aureus ◽  
Oxacillin Resistance ◽  
High Level ◽  
Selection Of

scholarly journals Penicillin-Binding Protein 2 Is Essential for Expression of High-Level Vancomycin Resistance and Cell Wall Synthesis in Vancomycin- Resistant Staphylococcus aureus Carrying the Enterococcal vanA Gene Complex

2004 ◽  
Vol 48 (12) ◽  
pp. 4566-4573 ◽  
Author(s):  
Anatoly Severin ◽  
Shang Wei Wu ◽  
Keiko Tabei ◽  
Alexander Tomasz
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Wall ◽  
Binding Protein ◽  
Inducible Promoter ◽  
Protein Product ◽  
Vancomycin Resistance ◽  
Penicillin Binding Protein ◽  
Oxacillin Resistance ◽  
Vancomycin Resistant ◽  
High Level

ABSTRACT A combination of biochemical and genetic experiments were performed in order to better understand the mechanism of expression of high-level vancomycin resistance in Staphylococcus aureus. The transcription of pbp2 of the highly vancomycin- and oxacillin-resistant strain COLVA200 and its mutant derivative with inactivated mecA were put under the control of an inducible promoter, and the dependence of oxacillin and vancomycin resistance and cell wall composition on the concentration of the isopropyl-β-d-thiogalactopyranoside inducer was determined. The results indicate that mecA—the genetic determinant of oxacillin resistance—while essential for oxacillin resistance, is not involved with the expression of vancomycin resistance. Penicillin binding protein 2A, the protein product of mecA, appears to be unable to utilize the depsipeptide cell wall precursor produced in the vancomycin-resistant cells for transpeptidation. The key penicillin binding protein essential for vancomycin resistance and for the synthesis of the abnormally structured cell walls characteristic of vancomycin-resistant S. aureus (A. Severin, K. Tabei, F. Tenover, M. Chung, N. Clarke, and A. Tomasz, J. Biol. Chem. 279:3398-3407, 2004) is penicillin binding protein 2.

scholarly journals β-Lactams Increase the Antibacterial Activity of Daptomycin against Clinical Methicillin-Resistant Staphylococcus aureus Strains and Prevent Selection of Daptomycin-Resistant Derivatives

2012 ◽  
Vol 56 (12) ◽  
pp. 6192-6200 ◽  
Author(s):  
Shrenik Mehta ◽  
Christopher Singh ◽  
Konrad B. Plata ◽  
Palas K. Chanda ◽  
Arundhati Paul ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Mutant Selection ◽  
Methicillin Resistant ◽  
Content Type ◽  
Oxacillin Resistance ◽  
Worm Model ◽  
Mrsa Strains ◽  
Selection Of

ABSTRACTMethicillin-resistantStaphylococcus aureus(MRSA) has emerged to be one of the most important pathogens both in health care and in community-onset infections. Daptomycin (DAP) is a cyclic anionic lipopeptide recommended for treatment of skin infections, bacteremia, and right-sided endocarditis caused by MRSA. Resistance to DAP (DAPr) has been reported in MRSA and is mostly accompanied by a parallel decrease in oxacillin resistance, a process known as the “seesaw effect.” Our study provides evidence that the seesaw effect applies to other β-lactams and carbapenems of clinical use, including nafcillin (NAF), cefotaxime (CTX), amoxicillin-clavulanic (AMC), and imipenem (IMP), in heterogeneous DAPrMRSA strains but not in MRSA strains expressing homogeneous β-lactam resistance. The antibacterial efficacy of DAP in combination with β-lactams was evaluated in isogenic DAP-susceptible (DAPs)/DaprMRSA strains originally obtained from patients that failed DAP monotherapy. Bothin vitro(MIC, synergy-kill curve) andin vivo(wax worm model) approaches were used. In these models, DAP and a β-lactam proved to be highly synergistic against both heterogeneous and homogeneous clinical DAPrMRSA strains. Mechanistically, β-lactams induced a reduction in the cell net positive surface charge, reverting the increased repulsion provoked by DAP alone, an effect that may favor the binding of DAP to the cell surface. The ease ofin vitromutant selection was observed when DAPsMRSA strains were exposed to DAP. Importantly, the combination of DAP and a β-lactam prevented the selection of DAPrvariants. In summary, our data show that the DAP–β-lactam combination may significantly enhance both thein vitroandin vivoefficacy of anti-MRSA therapeutic options against DAPrMRSA infections and represent an option in preventing DAPrselection in persistent or refractory MRSA infections.

scholarly journals Antibiotic Resistance as a Stress Response: Recovery of High-Level Oxacillin Resistance in Methicillin-Resistant Staphylococcus aureus “Auxiliary” (fem) Mutants by Induction of the Stringent Stress Response

2017 ◽  
Vol 61 (8) ◽  
Author(s):  
Choon Keun Kim ◽  
Catarina Milheiriço ◽  
Hermínia de Lencastre ◽  
Alexander Tomasz
Keyword(s):  
Staphylococcus Aureus ◽  
Antibiotic Resistance ◽  
Stress Response ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Penicillin Binding Protein ◽  
Methicillin Resistant ◽  
Content Type ◽  
Oxacillin Resistance ◽  
Response Recovery ◽  
High Level

ABSTRACT Studies with methicillin-resistant Staphylococcus aureus (MRSA) strain COL have shown that the optimal resistance phenotype requires not only mecA but also a large number of “auxiliary genes” identified by Tn551 mutagenesis. The majority of auxiliary mutants showed greatly increased levels of oxacillin resistance when grown in the presence of sub-MICs of mupirocin, suggesting that the mechanism of reduced resistance in the auxiliary mutants involved the interruption of a stringent stress response, causing reduced production of penicillin-binding protein 2A (PBP 2A).

scholarly journals In Vitro Selection of High-Level Beta-Lactam Resistance in Methicillin-Susceptible Staphylococcus aureus

Antibiotics ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 637
Author(s):  
Vladimir Gostev ◽  
Olga Kalinogorskaya ◽  
Ksenia Ivanova ◽  
Ekaterina Kalisnikova ◽  
Irina Lazareva ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
In Vitro Selection ◽  
Beta Lactam ◽  
Beta Lactams ◽  
Disk Diffusion Test ◽  
Amoxicillin Clavulanate ◽  
High Level ◽  
Derivatives Of ◽  
Selection Of

Selective pressure of beta-lactams is thought to be responsible for mutation selection in methicillin-susceptible Staphylococcus aureus (MSSA). We used next-generation sequencing to compare the genomes of beta-lactamase-positive (SA0707) and -negative (SA0937) MSSA isolates with their derivatives obtained after selection with oxacillin, ceftaroline, or meropenem. Selection with oxacillin and ceftaroline caused a rapid and significant (6–8 times) increase in the minimum inhibitory concentration (MICs) of oxacillin, penicillin, amoxicillin/clavulanate, and ceftaroline against the derivatives of both isolates, associated with growth impairment. Selection with meropenem caused a limited increase in the MICs of all beta-lactams against both isolates. During the initial stages of selection (after 5–15 passages), mutations were detected only in some reads, which indicated the heterogeneity of the population; however, during the later stages, either the population reversed to the wild type or fixation of the mutation was observed in the entire population. Selection with different beta-lactams caused diverse mutational events, but common mutations were detected in gdpP, all penicillin-binding proteins, cell wall regulators (vraST, graR), and deletions in the promoter region of pbp4. Therefore, the disk diffusion test with cefoxitin does not reveal resistance associated with these mechanisms in some cases, which can lead to the failure of beta-lactam therapy.

The Study of Bacillus Subtils Antimicrobial Activity on Some of the Pathological Isolates

2019 ◽  
Vol 9 (02) ◽  
Author(s):  
Hussein A Kadhum ◽  
Thualfakar H Hasan2
Keyword(s):  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Antimicrobial Activity ◽  
Bacillus Subtilis ◽  
Bacterial Growth ◽  
Broad Spectrum ◽  
Inhibitory Activity ◽  
Bacterial Pathogens ◽  
Inhibitory Ability ◽  
Selection Of

The study involved the selection of two isolates from Bacillus subtilis to investigate their inhibitory activity against some bacterial pathogens. B sub-bacteria were found to have a broad spectrum against test bacteria such as Staphylococcus aureus and Pseudomonas aeruginosa. They were about 23-30 mm and less against Klebsiella sp. The sensitivity of some antibodies was tested on the test samples. The results showed that the inhibitory ability of bacterial growth in the test samples using B. subtilis extract was more effective than the antibiotics used.

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