NaHCO3 modulates the bla operon and β-lactam susceptibility in borderline oxacillin-resistant Staphylococcus aureus (BORSA). Methicillin-resistant Staphylococcus aureus (MRSA) are resistant to nearly all β-lactam antibiotics under standard testing conditions. However, a novel phenotype exists wherein certain MRSA strains exhibit β-lactam susceptibility in the presence of bicarbonate (termed of NaHCO3 specifically on the bla operon via investigations of the impact of NaHCO3 on β-lactamase hyper-producing, mecA-negative, borderline oxacillin-resistant Staphylococcus aureus (BORSA) strains. Evaluate the effect of NaHCO3 on β-lactam susceptibility via minimum inhibitory concentrations (MIC) assay, expression of genes within the bla operon (blaZ, blaI, blaR1) via RT-qPCR, and β-lactamase (BlaZ
Antibacterial activity of menadione alone and in combination with oxacillin against methicillin-resistant Staphylococcus aureus and its impact on biofilms. Antibiotic resistance is a major threat to public health, particularly with methicillin-resistant (MRSA) being a leading cause of antimicrobial resistance. To combat this problem, drug repurposing offers a promising solution for the discovery of new antibacterial agents. Menadione exhibits antibacterial activity against methicillin-sensitive and methicillin-resistant strains, both alone and in combination with oxacillin. Its primary mechanism of action involves inducing oxidative stress. Sensitivity assays were performed using broth microdilution. The interaction between menadione, oxacillin, and antioxidants was assessed using
Failure of mecA/mecC PCR Testing to Accurately Predict Oxacillin Resistance in a Patient with Staphylococcus aureus Infective Endocarditis. Genotypic testing for / is heavily relied upon for rapid optimization of antimicrobial therapy in infections due to Staphylococcus aureus. Little is known regarding optimal reporting and/or therapy for patients demonstrating lack of genotypic evidence of or but phenotypic oxacillin resistance. We report a case of a 77-year-old patient with S. aureus bloodstream infection and infective endocarditis with discordance between genotypic results and phenotypic susceptibility testing.
Case Commentary: The hidden side of oxacillin resistance in Staphylococcus aureus. Acquisition of PBP2a (encoded by the gene) is the key resistance mechanism to β-lactams in . The gene can be easily detected by PCR assays; however, these tools will miss c-independent oxacillin resistance. This phenotype is mediated by mutations in cell wall metabolism genes that can be acquired during persistent infections under prolonged antibiotic exposure. The complex case presented by Hess et al. (Antimicrob Agents Chemother 67:e00437-23, 2023, https://doi.org/10.1128/aac.00437-23) highlights the diagnostic and therapeutic challenges in the management of c-independent oxacillin resistance.
Characterization of oxacillin-resistant Staphylococcus lugdunensis isolated from sterile body fluids in a medical center in Taiwan: A 12-year longitudinal epidemiological study. In this study, our objective was to characterize Staphylococcus lugdunensis isolated from sterile body fluids (SBFs) in a medical center in Taiwan between 2009 and 2020. We used MALDI-TOF MS, disk diffusion testing, agar dilution assay, SCCmec typing, and antibiotic resistance gene screening to identify and investigate the characteristics of oxacillin-resistant S. lugdunensis (ORSL). A total of 438 S. lugdunensis isolates were collected and 146 (33.3%) isolates were identified as ORSL. SCCmec type V was dominant (65.7%) in our ORSL isolates, followed by SCCmec type II (18.5%), and type IV (8.9%). After 2013, a slight
Accurate detection of oxacillin-resistant Staphylococcus lugdunensis by use of agar dilution. Staphylococcus lugdunensis is a Gram-positive coagulase-negative bacterium and is recognized as a critical pathogenic species recently. Here, we aimed to evaluate the cefoxitin disk diffusion (CDD), oxacillin agar dilution (OAD), and mecA PCR for detecting oxacillin-resistant S. lugdunensis (ORSL ) isolates. Multilocus sequence typing (MLST) analysis was performed to determine the clonality of 117 S. lugdunensis isolates isolated between May 2009 and Jul 2014. CDD, OAD, and mecA PCR were used to identify oxacillin-resistant S. lugdunensis (ORSL). MLST results showed that the most common sequence type (ST) of our S. lugdunensis isolates was ST6 (35.9%) followed by ST3 (28.2%), ST27 (17.9%), and ST4
Regulation of bla system in ST59-related oxacillin-susceptible mecA-positive Staphylococcus aureus. Oxacillin-susceptible mecA-positive Staphylococcus aureus (OS-MRSA) is clinically significant and isolated globally but the mechanism of its occurrence remains indistinct. We sought to assess the mechanism of regulating oxacillin susceptibility in OS-MRSA isolates by evaluating the evolutionary dynamics of OS-MRSA and the discrepancies of mecA-regulating genes in OS-MRSA and oxacillin-resistant MRSA (OR-MRSA). Nine OS-MRSA isolates and 77 OR-MRSA isolates were sequenced using next-generation sequencing (NGS) platforms. Two representative OS-MRSA isolates (ET-13, ET-16) were induced to be oxacillin resistant and sequenced also. OS-MRSA ET-16 and its counterpart isolate with induced oxacillin
In Vitro Antibacterial Experiments of Qixingjian Decoction and Its Synergistic Interaction with Oxacillin against Clinical Isolates of Methicillin-Resistant Staphylococcus aureus. With the widespread use and abuse of antimicrobial drugs, the problem of bacterial resistance is becoming increasingly prominent. The clinical detection rate of drug-resistant bacteria is increasing year by year, so of QXJT and explored its synergistic interaction with oxacillin (OX) and the mechanism of its antimicrobial activity. The antimicrobial activity of QXJT against methicillin-resistant (MRSA) was determined by the microdilution method, the broth macrodilution method, and the time-kill curve method. The main compounds in QXJT were analyzed by ultra-performance liquid chromatography. The synergistic
Treatment of Persistent Methicillin-Susceptible Staphylococcus aureus Bacteremia and Presumed Osteomyelitis with Oxacillin and Ertapenem in a Premature Neonate. Neonatal sepsis remains a high cause of morbidity and mortality in preterm neonates. Methicillin-susceptible Staphylococcus aureus (MSSA) can cause persistent bloodstream infections and invasive disease in neonates. We report the first published case of persistent MSSA bacteremia in a preterm neonate successfully treated with oxacillin and ertapenem combination therapy.
Comparison of carbapenem minimum inhibitory concentrations of Oxacillin-48-like Klebsiella pneumoniae by Sensititre, Vitek 2, MicroScan, and Etest. The aim of this laboratory-based study was to compare carbapenem MICs yielded by Sensititre, Vitek 2, MicroScan WalkAway plus and Etest for Oxacillin (OXA)-48-like Klebsiella pneumoniae isolates. Analysis was performed for categorical agreement
Current status of oxacillin-susceptible mecA-positive Staphylococcus aureus infection in Shanghai, China: A multicenter study. Oxacillin-susceptible mecA-positive Staphylococcus aureus (OS-MRSA) represents an important issue, as its oxacillin susceptibility has contributed to misidentification by conventional susceptibility tests and consequently potential therapeutic failure, but limited data mutations within mecA promoter. OS-MRSA had inducible oxacillin resistance and significantly lower MDR (Multi-Drug Resistant) rate. We observed that the VITEK 2 system exhibited some deficiency in OS-MRSA detection, whereas cefoxitin disk diffusion was shown to be a reliable and cost-saving alternative and should be supplemented in detecting S. aureus with borderline oxacillin susceptible MICs. This study
Oxacillin An official website of the United States government Here's how you know Log inAccess keysNCBI HomepageMyNCBI HomepageMain ContentMain NavigationBookshelfSearch databaseBooksAll DatabasesAssemblyBiocollectionsBioProjectBioSampleBooksClinVarConserved DomainsdbGaPdbVarGeneGenomeGEO DataSetsGEO ProfilesGTRHomoloGeneIdentical Protein GroupsMedGenMeSHNLM and EffectsSummary of Use during LactationLimited information indicates that oxacillin produces low levels in milk that are not expected to cause adverse effects in breastfed infants. Occasionally disruption of the infant's gastrointestinal flora, resulting in diarrhea or thrush have been reported with penicillins, but these effects have not been adequately evaluated. Oxacillin is acceptable in nursing
Disproportionality Analysis of Safety with Nafcillin and Oxacillin with the FDA Adverse Event Reporting System (FAERS). Antistaphylococcal penicillins such as nafcillin and oxacillin are among the first choices of treatment for severe invasive methicillin-susceptible (MSSA) infections, although there has been limited safety evaluations between individual agents. Using the FDA Adverse Event Reports System (FAERS), oxacillin was observed to have a lower proportion of reports of acute renal failure (reporting odds ratio [ROR], 5.3 [95% confidence interval {CI}, 3.1 to 9.3] versus 21.3 [95% CI, 15.8 to 28.6], respectively) and hypokalemia (ROR, 0.7 [95% CI, 0.1 to 4.8] versus 11.4 [95% CI, 7.1 to 18.3], respectively) than nafcillin.
Stealth MRSA: Emergence of resistance in oxacillin-susceptible MRSA due to mecA sequence instability. strains that possess a gene but are phenotypically susceptible to oxacillin and cefoxitin (OS-MRSA) have been recognized for over a decade and are a challenge for diagnostic laboratories. The mechanisms underlying the discrepancy vary from isolate to isolate. We characterized seven OS -MRSA clinical isolates of six different types from six different states by whole-genome sequencing to identify the nucleotide sequence changes leading to the OS-MRSA phenotype. The results demonstrated that oxacillin susceptibility was associated with mutations in regions of nucleotide repeats within Subinhibitory antibiotic exposure selected for secondary mutations that restored oxacillin
Identification of small molecules exhibiting oxacillin synergy through a novel assay for inhibition of vraTSR expression in methicillin resistant Staphylococcus aureus. Methicillin-resistant (MRSA) strains that are resistant to all forms of penicillin have become an increasingly common and urgent problem threatening human health. They are responsible for a wide variety of infectious diseases ranging from minor skin abscesses to life-threatening severe infections. The operon that is conserved among strains encodes a three-component signal transduction system () that is responsible for sensing and responding to cell wall stress. We developed a novel and multifaceted assay to identify compounds that potentiate the activity of oxacillin, essentially restoring efficacy
Characterization of a novel, type II staphylococcal cassette chromosome mec element from an endemic oxacillin-resistant Staphylococcus lugdunensis clone in a hospital setting. Staphylococcus lugdunensis is a significant pathogen that causes community-acquired and nosocomial infections. The high prevalence of oxacillin-resistant S. lugdunensis (ORSL) is of major concern. Resistance to β-lactams
EUCAST disc diffusion criteria for the detection of mecA-Mediated β-lactam resistance in Staphylococcus pseudintermedius: oxacillin versus cefoxitin. Until recently, the European Committee on Antimicrobial Susceptibility Testing (EUCAST) recommended the cefoxitin disc to screen for mecA-mediated β-lactam resistance in Staphylococcus pseudintermedius. A recent study indicated that cefoxitin was inferior to oxacillin in this respect. We have re-evaluated cefoxitin and oxacillin discs for screening for methicillin resistance in S. pseudintermedius. We included 224 animal and human S. pseudintermedius isolates from Europe (n = 108) and North America (n = 116), of which 109 were mecA-positive. Disc diffusion was performed per EUCAST recommendations using 30-μg cefoxitin and 1-μg oxacillin discs
The role of ArlRS in regulating oxacillin susceptibility in methicillin-resistant Staphylococcus aureus indicates it is a potential target for antimicrobial resistance breakers. Methicillin-resistant Staphylococcus aureus (MRSA), also known as oxacillin-resistant S. aureus, is a leading cause of community and hospital associated infections globally. In this work, we found that deletion of the arlRS two-component system genes in the USA300 and USA500 strains resulted in increased susceptibilities to oxacillin (8-16-fold decrease in minimal inhibitory concentrations). In USA300ΔarlRS, transcriptional levels of mecA or blaZ showed no obvious change, while mRNA levels of spx showed a 4-fold decrease at 4 h and a 6.3-fold decrease at 10 h. Overexpression of spx in ΔarlRS restored oxacillin
Evaluation of Oxacillin and Cefoxitin Disk Diffusion and MIC Breakpoints Established by the Clinical and Laboratory Standards Institute for Detection of mecA-Mediated Oxacillin Resistance in Staphylococcus schleiferi is a beta-hemolytic, coagulase-variable colonizer of small animals that can cause opportunistic infections in humans. In veterinary isolates, the rate of -mediated oxacillin resistance is significant, with reported resistance rates of >39%. The goal of this study was to evaluate oxacillin and cefoxitin disk diffusion (DD) and MIC breakpoints for detection of -mediated oxacillin resistance in 52 human and 38 veterinary isolates of Isolates were tested on multiple brands of commercial media and according to Clinical and Laboratory Standards Institute (CLSI) methods. Zone
Genetic diversity among S. aureus isolates showing oxacillin and/or cefoxitin resistance not linked to the presence of mec genes. Methicillin-resistant isolates lacking genes ( = 32), collected from Belgian hospitals, were characterized for their β-lactamase production and the presence of mutations in genes, the promoter, and genes involved in penicillin-binding protein 4