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 β-Lactam Antibiotics Targeting PBP1 Selectively Enhance Daptomycin Activity against Methicillin-Resistant Staphylococcus aureus

2013 ◽  
Vol 57 (10) ◽  
pp. 5005-5012 ◽  
Author(s):  
Andrew D. Berti ◽  
George Sakoulas ◽  
Victor Nizet ◽  
Ryan Tewhey ◽  
Warren E. Rose
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Division ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Binding Protein ◽  
Membrane Insertion ◽  
Penicillin Binding Protein ◽  
Compensatory Response ◽  
Binding Profile ◽  
Methicillin Resistant ◽  
Content Type

ABSTRACTThe activity of daptomycin (DAP) against methicillin-resistantStaphylococcus aureus(MRSA) is enhanced in the presence of subinhibitory concentrations of antistaphylococcal β-lactam antibiotics by an undefined mechanism. Given the variability in the penicillin-binding protein (PBP)-binding profiles of different β-lactam antibiotics, the purpose of this study was to examine the relative enhancement of DAP activity against MRSA by different β-lactam antibiotics to determine if a specific PBP-binding profile is associated with the ability to enhance the anti-MRSA activity of DAP. We determined that both broad- and narrow-spectrum β-lactam antibiotics known to exhibit PBP1 binding demonstrated potent enhancement of DAP anti-MRSA activity, whereas β-lactam antibiotics with minimal PBP1 binding (cefoxitin, ceftriaxone, cefaclor, and cefotaxime) were less effective. We suspect that PBP1 disruption by β-lactam antibiotics affects pathways of cell division inS. aureusthat may be a compensatory response to DAP membrane insertion, resulting in DAP hypersusceptibility.

scholarly journals Chlorhexidine and Mupirocin Susceptibility of Methicillin-Resistant Staphylococcus aureus Isolates in the REDUCE-MRSA Trial

2016 ◽  
Vol 54 (11) ◽  
pp. 2735-2742 ◽  
Author(s):  
Mary K. Hayden ◽  
Karen Lolans ◽  
Katherine Haffenreffer ◽  
Taliser R. Avery ◽  
Ken Kleinman ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Cluster Randomized Trial ◽  
Confidence Limits ◽  
Methicillin Resistant ◽  
Content Type ◽  
Mrsa Infection ◽  
Mupirocin Resistance ◽  
Cluster Randomized ◽  
High Level

Whether targeted or universal decolonization strategies for the control of methicillin-resistant Staphylococcus aureus (MRSA) select for resistance to decolonizing agents is unresolved. The REDUCE-MRSA trial (ClinicalTrials registration no. NCT00980980) provided an opportunity to investigate this question. REDUCE-MRSA was a 3-arm, cluster-randomized trial of either screening and isolation without decolonization, targeted decolonization with chlorhexidine and mupirocin, or universal decolonization without screening to prevent MRSA infection in intensive-care unit (ICU) patients. Isolates from the baseline and intervention periods were collected and tested for susceptibility to chlorhexidine gluconate (CHG) by microtiter dilution; mupirocin susceptibility was tested by Etest. The presence of the qacA or qacB gene was determined by PCR and DNA sequence analysis. A total of 3,173 isolates were analyzed; 2 were nonsusceptible to CHG (MICs, 8 μg/ml), and 5/814 (0.6%) carried qacA or qacB . At baseline, 7.1% of MRSA isolates expressed low-level mupirocin resistance, and 7.5% expressed high-level mupirocin resistance. In a mixed-effects generalized logistic regression model, the odds of mupirocin resistance among clinical MRSA isolates or MRSA isolates acquired in an ICU in intervention versus baseline periods did not differ across arms, although estimates were imprecise due to small numbers. Reduced susceptibility to chlorhexidine and carriage of qacA or qacB were rare among MRSA isolates in the REDUCE-MRSA trial. The odds of mupirocin resistance were no different in the intervention versus baseline periods across arms, but the confidence limits were broad, and the results should be interpreted with caution.

scholarly journals Full-Genome Sequencing Identifies in the Genetic Background Several Determinants That Modulate the Resistance Phenotype in Methicillin-Resistant Staphylococcus aureus Strains Carrying the Novel mecC Gene

2017 ◽  
Vol 61 (3) ◽  
Author(s):  
Catarina Milheiriço ◽  
Hermínia de Lencastre ◽  
Alexander Tomasz
Keyword(s):  
Staphylococcus Aureus ◽  
Antibiotic Resistance ◽  
Genetic Background ◽  
Beta Lactam ◽  
Methicillin Resistant ◽  
Content Type ◽  
Resistance Phenotype ◽  
Beta Lactam Antibiotics ◽  
Oxacillin Resistance ◽  
Mrsa Strains

ABSTRACT Most methicillin-resistant Staphylococcus aureus (MRSA) strains are resistant to beta-lactam antibiotics due to the presence of the mecA gene, encoding an extra penicillin-binding protein (PBP2A) that has low affinity for virtually all beta-lactam antibiotics. Recently, a new resistance determinant—the mecC gene—was identified in S. aureus isolates recovered from humans and dairy cattle. Although having typically low MICs to beta-lactam antibiotics, MRSA strains with the mecC determinant are also capable of expressing high levels of oxacillin resistance when in an optimal genetic background. In order to test the impact of extensive beta-lactam selection on the emergence of mecC-carrying strains with high levels of antibiotic resistance, we exposed the prototype mecC-carrying MRSA strain, LGA251, to increasing concentrations of oxacillin. LGA251 was able to rapidly adapt to high concentrations of oxacillin in growth medium. In such laboratory mutants with increased levels of oxacillin resistance, we identified mutations in genes with no relationship to the mecC regulatory system, indicating that the genetic background plays an important role in the establishment of the levels of oxacillin resistance. Our data also indicate that the stringent stress response plays a critical role in the beta-lactam antibiotic resistance phenotype of MRSA strains carrying the mecC determinant.

scholarly journals Profile of antibiotic-resistant and presence of methicillin-resistant Staphylococcus aureus from nasal swab of dogs from several animal clinics in Surabaya, Indonesia

2020 ◽  
Vol 6 (1) ◽  
pp. 90-94
Author(s):  
Vega Decline ◽  
Mustofa Helmi Effendi ◽  
Reina Puspita Rahmaniar ◽  
Sheila Marty Yanestria ◽  
Nenny Harijani
Keyword(s):  
Staphylococcus Aureus ◽  
Antibiotic Resistance ◽  
Nasal Swab ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Antibiotic Sensitivity ◽  
Diffusion Method ◽  
Disk Diffusion Method ◽  
Antibiotic Resistant ◽  
Methicillin Resistant ◽  
Oxacillin Resistance

Aim: The research was to investigate the antibiotic resistance profile and to screen for methicillin-resistant Staphylococcus aureus (MRSA) from nasal mucosa swab of dogs. Materials and Methods: The samples were collected from three pet clinics, three K9 units, one veterinary teaching hospital, and one kennel in Surabaya. Of the 50 total samples, 24 confirmed S. aureus strains, which were used for antibiotic sensitivity tests using a disk diffusion method and screening of MRSA used oxacillin resistance screening for base (ORSAB). Results: This study showed that there were differences in antibiotic resistance patterns among different locations. Fourteen isolates were screened for MRSA by culture on ORSAB. Conclusion: MRSA carriage was found on nasal swab of dogs, and dogs can act as reservoir of MRSA for spreading to human health. Keywords: antibiotic-resistant, dogs, methicillin-resistant Staphylococcus aureus, Staphylococcus aureus.

scholarly journals Role of the Stringent Stress Response in the Antibiotic Resistance Phenotype of Methicillin-Resistant Staphylococcus aureus

2016 ◽  
Vol 60 (4) ◽  
pp. 2311-2317 ◽  
Author(s):  
Sandra Aedo ◽  
Alexander Tomasz
Keyword(s):  
Staphylococcus Aureus ◽  
Stress Response ◽  
Phenotypic Expression ◽  
Beta Lactam ◽  
Resistance Level ◽  
Methicillin Resistant ◽  
Content Type ◽  
Resistance Phenotype ◽  
Oxacillin Resistance ◽  
The Impact

ABSTRACTResistance to beta-lactam antibiotics in methicillin-resistantStaphylococcus aureus(MRSA) requires the presence of an acquired genetic determinant,mecAormecC, which encode penicillin-binding protein PBP2A or PBP2A′, respectively. Although all MRSA strains share a mechanism of resistance, the phenotypic expression of beta-lactam resistance shows considerable strain-to-strain variation. The stringent stress response, a stress response that results from nutrient limitation, was shown to play a key role in determining the resistance level of an MRSA strain. In the present study, we validated the impact of the stringent stress response on transcription and translation ofmecAin the MRSA clinical isolate strain N315, which also carries known regulatory genes (mecI/mecR1/mecR2andblaI/blaR1) formecAtranscription. We showed that the impact of the stringent stress response on the resistance level may be restricted to beta-lactam resistance based on a “foreign” determinant such asmecA, as opposed to resistance based on mutations in the nativeS. aureusdeterminantpbpB(encoding PBP2). Our observations demonstrate that high-level resistance mediated by the stringent stress response follows the current model of beta-lactam resistance in which the native PBP2 protein is also essential for expression of the resistance phenotype. We also show that theStaphylococcus sciuri pbpDgene (also calledmecAI), the putative evolutionary precursor ofmecA, confers oxacillin resistance in anS. aureusstrain, generating a heterogeneous phenotype that can be converted to high and homogenous resistance by induction of the stringent stress response in the bacteria.

scholarly journals PBP2a Mutations Causing High-Level Ceftaroline Resistance in Clinical Methicillin-Resistant Staphylococcus aureus Isolates

2014 ◽  
Vol 58 (11) ◽  
pp. 6668-6674 ◽  
Author(s):  
S. Wesley Long ◽  
Randall J. Olsen ◽  
Shrenik C. Mehta ◽  
Timothy Palzkill ◽  
Patricia L. Cernoch ◽  
...  
Keyword(s):  
United States ◽  
Staphylococcus Aureus ◽  
Binding Pocket ◽  
The United States ◽  
Penicillin Binding Protein ◽  
Methicillin Resistant ◽  
Content Type ◽  
Mrsa Strains ◽  
Biochemical Analyses ◽  
High Level

ABSTRACTCeftaroline is the first member of a novel class of cephalosporins approved for use in the United States. Although prior studies have identified eight ceftaroline-resistant methicillin-resistantStaphylococcus aureus(MRSA) isolates in Europe and Asia with MICs ranging from 4 to 8 mg/liter, high-level resistance to ceftaroline (>32 mg/liter) has not been described in MRSA strains isolated in the United States. We isolated a ceftaroline-resistant (MIC > 32 mg/liter) MRSA strain from the blood of a cystic fibrosis patient and five MRSA strains from the respiratory tract of this patient. Whole-genome sequencing identified two amino acid-altering mutations uniquely present in the ceftaroline-binding pocket of the transpeptidase region of penicillin-binding protein 2a (PBP2a) in ceftaroline-resistant isolates. Biochemical analyses and the study of isogenic mutant strains confirmed that these changes caused ceftaroline resistance. Thus, we identified the molecular mechanism of ceftaroline resistance in the first MRSA strain with high-level ceftaroline resistance isolated in the United States.

scholarly journals Ceftobiprole- and Ceftaroline-Resistant Methicillin-Resistant Staphylococcus aureus

2015 ◽  
Vol 59 (5) ◽  
pp. 2960-2963 ◽  
Author(s):  
Liana C. Chan ◽  
Li Basuino ◽  
Binh Diep ◽  
Stephanie Hamilton ◽  
Som S. Chatterjee ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Methicillin Resistant ◽  
Content Type ◽  
Low Level ◽  
Mrsa Strains ◽  
High Level ◽  
Level Resistance

ABSTRACTThe role ofmecAmutations in conferring resistance to ceftobiprole and ceftaroline, cephalosporins with anti-methicillin-resistantStaphylococcus aureus(MRSA) activity, was determined with MRSA strains COL and SF8300. The SF8300 ceftaroline-passaged mutant carried a singlemecAmutation, E447K (E-to-K change at position 447), and expressed low-level resistance. This mutation in COL conferred high-level resistance to ceftobiprole but only low-level resistance to ceftaroline. The COL ceftaroline-passaged mutant, which expressed high-level resistance to ceftobiprole and ceftaroline, had mutations inpbp2,pbp4, andgdpPbut notmecA.

scholarly journals Microtiter Plate-Based Assay for Inhibitors of Penicillin-Binding Protein 2a from Methicillin-Resistant Staphylococcus aureus

2011 ◽  
Vol 55 (6) ◽  
pp. 2783-2787 ◽  
Author(s):  
Sudheer Bobba ◽  
V. K. Chaithanya Ponnaluri ◽  
Mridul Mukherji ◽  
William G. Gutheil
Keyword(s):  
Staphylococcus Aureus ◽  
Binding Protein ◽  
Binding Constants ◽  
Public Health Problem ◽  
Microtiter Plate ◽  
Penicillin Binding Protein ◽  
Methicillin Resistant ◽  
Content Type ◽  
High Level

ABSTRACTPenicillin-binding protein 2a (PBP2a), the molecular determinant for high-level β-lactam resistance in methicillin-resistantStaphylococcus aureus(MRSA), is intrinsically resistant to most β-lactam antibiotics. The development and characterization of new inhibitors targeting PBP2a would benefit from an effective and convenient assay for inhibitor binding. This study was directed toward the development of a fluorescently detected β-lactam binding assay for PBP2a from MRSA. Biotinylated ampicillin and biotinylated cephalexin were tested as tagging reagents for fluorescence detection by using a streptavidin-horseradish peroxidase conjugate. Both bound surprisingly well to PBP2a, with binding constants of 1.6 ± 0.4 μM and 13.6 ± 0.8 μM, respectively. Two forms of the assay were developed, a one-step direct competition form of the assay and a two-step indirect competition form of the assay, and both forms of the assay gave comparable results. This assay was then used to characterize PBP2a binding to ceftobiprole, which gave results consistent with previous studies of ceftobiprole-PBP2a binding. This assay was also demonstrated for screening for PBP2a inhibitors by screening a set of 13 randomly selected β-lactams for PBP2a inhibition at 750 μM. Meropenem was observed to give substantial inhibition in this screen, and a follow-up titration experiment determined its apparentKito be 480 ± 70 μM. The availability of convenient and sensitive microtiter-plate based assays for the screening and characterization of PBP2a inhibitors is expected to facilitate the discovery and development of new PBP2a inhibitors for use in combating the serious public health problem posed by MRSA.

scholarly journals PBP 4 Mediates High-Level Resistance to New-Generation Cephalosporins in Staphylococcus aureus

2016 ◽  
Vol 60 (7) ◽  
pp. 3934-3941 ◽  
Author(s):  
Liana C. Chan ◽  
Aubre Gilbert ◽  
Li Basuino ◽  
Thaina M. da Costa ◽  
Stephanie M. Hamilton ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Core Genome ◽  
Binding Protein ◽  
Penicillin Binding Protein ◽  
Methicillin Resistant ◽  
Content Type ◽  
Resistant Strains ◽  
High Level ◽  
New Generation ◽  
Level Resistance

ABSTRACTStaphylococcus aureusis an important cause of both hospital- and community-associated methicillin-resistantS. aureus(MRSA) infections worldwide. β-Lactam antibiotics are the drugs of choice to treatS. aureusinfections, but resistance to these and other antibiotics make treatment problematic. High-level β-lactam resistance ofS. aureushas always been attributed to the horizontally acquired penicillin binding protein 2a (PBP 2a) encoded by themecAgene. Here, we show thatS. aureuscan also express high-level resistance to β-lactams, including new-generation broad-spectrum cephalosporins that are active against methicillin-resistant strains, through an uncanonical core genome-encoded penicillin binding protein, PBP 4, a nonessential enzyme previously considered not to be important for staphylococcal β-lactam resistance. Our results show that PBP 4 can mediate high-level resistance to β-lactams.

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