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Clinical Microbiology and Infection :... Dec 2022The 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...
OBJECTIVES
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.
METHODS
Analysis was performed for categorical agreement for ertapenem, meropenem, and imipenem, and the proportion of isolates with MICs ≤8μg/mL and the MIC50/MIC90 for meropenem and imipenem, from a convenience sample of 82 deduplicated blood culture OXA-48-like K. pneumoniae isolates.
RESULTS
The proportion of isolates testing susceptible to ertapenem by Etest (19/82, 23.1%) differed from Sensititre/Vitek (0/82) and MicroScan (2/82, 2.4%) (p < 0.001 for all). For meropenem, the proportion of isolates susceptible by Etest (31/82, 37.8%) differed from Sensititre/Vitek (16/82, 19.5%) (p = 0.015). There was variation in the proportion of isolates that tested imipenem susceptible when comparing Sensititre (9/82, 11%) and Vitek (8/82, 9.8%) to MicroScan (27/82, 32.9%), p = 0.001 and p < 0.001, respectively, Sensititre and Vitek to Etest (45/82, 54.9%), p < 0.001 for both, and MicroScan to Etest, p = 0.007. The proportion of isolates with meropenem MICs ≤8μg/mL with Sensititre and Vitek differed significantly from Etest, 58.5% and 85.4%, respectively, p < 0.001. A 2-fold difference between the Sensititre and Vitek meropenem and imipenem MIC at which ≥50% of isolates were inhibited compared to the MicroScan, and a 4-fold difference compared to Etest, was present.
CONCLUSIONS
Substantial variability in carbapenem MICs for OXA-48-like carbapenemase-producing Enterobacterales isolates by the four methods was demonstrated. Performance characteristics verification of MIC methods in use for the predominant carbapenemase-producing Enterobacterales type is required by laboratories to optimize the accuracy of carbapenem reporting.
Topics: Humans; Klebsiella pneumoniae; Carbapenems; Disk Diffusion Antimicrobial Tests; Meropenem; Ertapenem; Oxacillin; Anti-Bacterial Agents; Microbial Sensitivity Tests; beta-Lactamases; Imipenem
PubMed: 35811020
DOI: 10.1016/j.cmi.2022.06.023 -
Molecules (Basel, Switzerland) Jan 2022To meet the demand for alternatives to commonly used antibiotics, this paper evaluates the antimicrobial potential of arene-ruthenium(II) complexes and their salts,...
To meet the demand for alternatives to commonly used antibiotics, this paper evaluates the antimicrobial potential of arene-ruthenium(II) complexes and their salts, which may be of value in antibacterial treatment. Their antimicrobial activity (MIC, MBC/MFC) was examined in vitro against , , , and and compared with classic antibiotics used as therapeutics. Selected arene-ruthenium(II) complexes were found to have synergistic effects with oxacillin and vancomycin against staphylococci. Their bactericidal effect was found to be associated with cell lysis and the ability to cut microbial DNA. To confirm the safety of the tested arene-ruthenium(II) complexes in vivo, their cytotoxicity was also investigated against normal human foreskin fibroblasts (HFF-1). In addition, the antioxidant and thus pro-health potential of the compounds, i.e., their nonenzymatic antioxidant capacity (NEAC), was determined by two different methods: ferric-TPTZ complex and DPPH assay.
Topics: Anti-Bacterial Agents; Antioxidants; Cell Survival; Cells, Cultured; Drug Resistance, Microbial; Drug Synergism; Fibroblasts; Foreskin; Free Radical Scavengers; Humans; Hydrocarbons, Aromatic; Male; Oxacillin; Pyrazoles; Ruthenium Compounds; Staphylococcus aureus; Staphylococcus epidermidis; Vancomycin
PubMed: 35056783
DOI: 10.3390/molecules27020468 -
Antimicrobial Agents and Chemotherapy 2014Since the discovery and use of penicillin, the increase of antibiotic resistance among bacterial pathogens has become a major health concern. The most prevalent...
Since the discovery and use of penicillin, the increase of antibiotic resistance among bacterial pathogens has become a major health concern. The most prevalent resistance mechanism in Gram-negative bacteria is due to β-lactamase expression. Class D β-lactamases are of particular importance due to their presence in multidrug-resistant Acinetobacter baumannii and Pseudomonas aeruginosa. The class D enzymes were initially characterized by their ability to efficiently hydrolyze isoxazolyl-type β-lactams like oxacillin. Due to this substrate preference, these enzymes are traditionally referred to as oxacillinases or OXAs. However, this class is comprised of subfamilies characterized by diverse activities that include oxacillinase, carbapenemase, or cephalosporinase substrate specificity. OXA-1 represents one subtype of class D enzyme that efficiently hydrolyzes oxacillin, and OXA-24/40 represents another with weak oxacillinase, but increased carbapenemase, activity. To examine the structural basis for the substrate selectivity differences between OXA-1 and OXA-24/40, the X-ray crystal structures of deacylation-deficient mutants of these enzymes (Lys70Asp for OXA-1; Lys84Asp for OXA-24) in complexes with oxacillin were determined to 1.4 Å and 2.4 Å, respectively. In the OXA-24/40/oxacillin structure, the hydrophobic R1 side chain of oxacillin disrupts the bridge between Tyr112 and Met223 present in the apo OXA-24/40 structure, causing the main chain of the Met223-containing loop to adopt a completely different conformation. In contrast, in the OXA-1/oxacillin structure, a hydrophobic pocket consisting of Trp102, Met99, Phe217, Leu161, and Leu255 nicely complements oxacillin's nonpolar R1 side chain. Comparison of the OXA-1/oxacillin and OXA-24/40/oxacillin complexes provides novel insight on how substrate selectivity is achieved among subtypes of class D β-lactamases. By elucidating important active site interactions, these findings can also inform the design of novel antibiotics and inhibitors.
Topics: Bacterial Proteins; Catalytic Domain; Cephalosporinase; Crystallography, X-Ray; Oxacillin; Substrate Specificity; beta-Lactamases
PubMed: 24165180
DOI: 10.1128/AAC.01483-13 -
Scientific Reports May 2022The spread of multidrug-resistant bacteria, such as the skin commensal Staphylococcus aureus, is a worldwide health challenge; new methods to counteract opportunistic...
An animal derivative-free medium enhances Lactobacillus johnsonii LJO02 supernatant selective efficacy against the methicillin (oxacillin)-resistant Staphylococcus aureus virulence through key-metabolites.
The spread of multidrug-resistant bacteria, such as the skin commensal Staphylococcus aureus, is a worldwide health challenge; new methods to counteract opportunistic pathogen growth and virulence are urgent. We compared the activity of Lacticaseibacillus rhamnosus LR06 (DSM 21981) and Lactobacillus johnsonii LJO02 (DSM 33828) cell-free supernatants (CFSs) produced in the conventional animal derivative-based MRS medium and an innovative animal derivative-free broth (TIL) versus the MDR S. aureus (ATCC 43300). CFS influence was assessed towards the viability, metabolic activity, and ability to form biofilm of the MDR strain through optical density, alamarBlue assay, and crystal violet staining; their content in short-chain fatty acids, lactic acid, and proteins was analysed via high-resolution mass spectrometry and gas chromatography. All CFSs reduce viable and metabolically active S. aureus, being TIL more efficient compared to MRS in stimulating lactic acid bacteria metabolism and decreasing S. aureus biofilm formation. Particularly, the CFS from LJO02 grown in TIL has the best efficacy, revealing a high amount of lactic acid and 59 peculiar proteins; its effectiveness is partially maintained upon trypsin and proteinase K treatments, but not by pepsin and pH basification. Therefore, antagonistic CFSs may represent a strategic prevention approach, with bacteriotherapeutic and bio-repair potential.
Topics: Animals; Anti-Bacterial Agents; Biofilms; Lactic Acid; Lactobacillus johnsonii; Methicillin; Methicillin-Resistant Staphylococcus aureus; Microbial Sensitivity Tests; Oxacillin; Staphylococcus aureus; Virulence
PubMed: 35606510
DOI: 10.1038/s41598-022-12718-z -
The Journal of Antimicrobial... Dec 2021The cyclic anionic lipopeptide daptomycin is used in the treatment of severe infections caused by Gram-positive pathogens, including MRSA. Daptomycin resistance,...
BACKGROUND
The cyclic anionic lipopeptide daptomycin is used in the treatment of severe infections caused by Gram-positive pathogens, including MRSA. Daptomycin resistance, although rare, often results in treatment failure. Paradoxically, in MRSA, daptomycin resistance is usually accompanied by a concomitant decrease in β-lactam resistance in what is known as the 'see-saw effect'. This resensitization is extensively used for the treatment of MRSA infections, by combining daptomycin and a β-lactam antibiotic, such as oxacillin.
OBJECTIVES
We aimed: (i) to investigate the combined effects of daptomycin and oxacillin on the lipid composition of the cellular membrane of both daptomycin-resistant and -susceptible MRSA strains; and (ii) to assess the involvement of the post-translocational protein PrsA, which plays an important role in oxacillin resistance in MRSA, in membrane lipid composition and remodelling during daptomycin resistance/β-lactam sensitization.
RESULTS
The combination of microbiological and biochemical studies, with fluorescence microscopy using lipid probes, showed that the lipid composition and surface charge of the daptomycin-resistant cells exposed to daptomycin/oxacillin were dependent on antibiotic concentration and directly associated with PrsA, which influenced cardiolipin remodelling/relocation.
CONCLUSIONS
Our findings show that PrsA, in addition to its post-transcriptional role in the maturation of PBP 2a, is a key mediator of cell membrane remodelling connected to the see-saw effect and may have a key role in the resensitization of daptomycin-resistant strains to β-lactams, such as oxacillin.
Topics: Anti-Bacterial Agents; Bacterial Proteins; Daptomycin; Lipoproteins; Membrane Lipids; Membrane Proteins; Methicillin-Resistant Staphylococcus aureus; Microbial Sensitivity Tests; Oxacillin; beta-Lactams
PubMed: 34618036
DOI: 10.1093/jac/dkab356 -
Scientific Reports Feb 2018Infective endocarditis (IE) is associated with high morbidity and mortality rates. The predominant bacteria causing IE is Staphylococcus aureus (S. aureus), which can...
Infective endocarditis (IE) is associated with high morbidity and mortality rates. The predominant bacteria causing IE is Staphylococcus aureus (S. aureus), which can bind to existing thrombi on heart valves and generate vegetations (biofilms). In this in vitro flow study, we evaluated sonobactericide as a novel strategy to treat IE, using ultrasound and an ultrasound contrast agent with or without other therapeutics. We developed a model of IE biofilm using human whole-blood clots infected with patient-derived S. aureus (infected clots). Histology and live-cell imaging revealed a biofilm layer of fibrin-embedded living Staphylococci around a dense erythrocyte core. Infected clots were treated under flow for 30 minutes and degradation was assessed by time-lapse microscopy imaging. Treatments consisted of either continuous plasma flow alone or with different combinations of therapeutics: oxacillin (antibiotic), recombinant tissue plasminogen activator (rt-PA; thrombolytic), intermittent continuous-wave low-frequency ultrasound (120-kHz, 0.44 MPa peak-to-peak pressure), and an ultrasound contrast agent (Definity). Infected clots exposed to the combination of oxacillin, rt-PA, ultrasound, and Definity achieved 99.3 ± 1.7% loss, which was greater than the other treatment arms. Effluent size measurements suggested low likelihood of emboli formation. These results support the continued investigation of sonobactericide as a therapeutic strategy for IE.
Topics: Biofilms; Contrast Media; Endocarditis; Humans; Oxacillin; Staphylococcus aureus; Thrombosis; Tissue Plasminogen Activator; Ultrasonography
PubMed: 29467474
DOI: 10.1038/s41598-018-21648-8 -
Annals of Clinical Microbiology and... Jun 2011There is no clear relationship between in vitro bactericidal activity tests and clinical outcome. We studied bactericidal activity of oxacillin, vancomycin and...
Bactericidal activity of oxacillin and glycopeptides against Staphylococcus aureus in patients with endocarditis: looking for a relationship between tolerance and outcome.
BACKGROUND
There is no clear relationship between in vitro bactericidal activity tests and clinical outcome. We studied bactericidal activity of oxacillin, vancomycin and teicoplanin against Staphylococcus aureus isolates in patients with endocarditis and then we sought to determine if there was a relationship between in vitro bactericidal activity and clinical outcome.
METHODS
Minimal bacteriostatic and minimal bactericidal concentrations were determined for Staphylococcus aureus strains isolated from patients with endocarditis following standardized methods. Medical records were reviewed retrospectively to collect data on antimicrobial susceptibility at admission, antimicrobial therapy, need for surgery, embolic events and outcome.
RESULTS AND DISCUSSION
Sixty-two Staphylococcus aureus strains were studied in 62 patients with endocarditis. Overall, 91.9% definite, 21% methicillin resistant and 72.6% cured. Surgery was performed in 32.3% and embolic events were documented in 64.5%. Tolerance to oxacillin and teicoplanin was more common than vancomycin tolerance among methicillin susceptible Staphylococcus aureus. Among methicillin resistant Staphylococcus aureus teicoplanin was shown to have a higher rate of tolerance than vancomycin. No statistically significant differences on clinical outcome between oxacillin tolerant and oxacillin non tolerant Staphylococcus aureus infections were observed. Tolerance to oxacillin did not adversely affect clinical outcomes of patients with methicillin susceptible Staphylococcus aureus endocarditis treated with a combination of antimicrobials including oxacillin. The cure rate was significantly lower among patients with methicillin resistant Staphylococcus aureus endocarditis.
CONCLUSIONS
In vitro bactericidal test results were not valid predictors of clinical outcome. Physicians need to use additional parameters when treating patients with staphylococcal endocarditis.
Topics: Adult; Anti-Bacterial Agents; Drug Resistance, Bacterial; Drug Therapy, Combination; Endocarditis, Bacterial; Female; Glycopeptides; Humans; Male; Oxacillin; Retrospective Studies; Serum Bactericidal Test; Staphylococcal Infections; Staphylococcus aureus; Treatment Outcome
PubMed: 21658248
DOI: 10.1186/1476-0711-10-26 -
Journal of Global Antimicrobial... Sep 2020Recently, mecA-negative Staphylococcus aureus strains with decreased susceptibility to oxacillin have been sporadically reported worldwide. They have been called...
OBJECTIVES
Recently, mecA-negative Staphylococcus aureus strains with decreased susceptibility to oxacillin have been sporadically reported worldwide. They have been called borderline oxacillin-resistant S. aureus (BORSA). S. aureus β-lactamase (BlaZ), which is encoded by the blaZ gene, is categorized as a class A β-lactamase (penicillinase); hence, its hydrolytic activity against oxacillin, cephems, and carbapenems is low. The aim of this study was to clarify the mechanism of oxacillin resistance in BORSA.
METHODS
Clinical BORSA (MIC=1μg/mL) and methicillin-susceptible S. aureus (MSSA; MIC=0.25μg/mL) isolates carrying blaZ were used. Amino acid sequencing, oxacillin susceptibility testing and evaluation of oxacillin hydrolysis activity were conducted.
RESULTS
The S. aureus RN4220 strain carrying blaZ derived from BORSA was found to have decreased susceptibility to oxacillin compared with a strain carrying blaZ from an MSSA strain. The BlaZ (BORSA) differentiated six amino acids (M10I, E112A, K193E, N196K, F203L and N207S) compared with BlaZ (MSSA). Based on the amino acid sequences, BlaZ (BORSA) and BlaZ (MSSA) were classified into different serological types A and C, respectively. The recombinant BlaZ (BORSA) was found to hydrolyse oxacillin faster than BlaZ (MSSA). Additionally, site-directed mutagenesis showed that an alanine at position 112 of the amino acid sequence of BlaZ (BORSA) plays an important role in the hydrolysis of oxacillin.
CONCLUSION
Our findings strongly suggest that type A staphylococcal β-lactamase acts as an extended-spectrum β-lactamase and contributes to borderline resistance to oxacillin in S. aureus.
Topics: Anti-Bacterial Agents; Methicillin-Resistant Staphylococcus aureus; Oxacillin; Staphylococcus aureus; beta-Lactamases
PubMed: 32200127
DOI: 10.1016/j.jgar.2020.03.002 -
BMC Complementary and Alternative... Sep 2017The emergence of multidrug-resistant bacteria is a worldwide concern and in order to find an alternative to this problem, the occurrence of antimicrobial compounds in...
BACKGROUND
The emergence of multidrug-resistant bacteria is a worldwide concern and in order to find an alternative to this problem, the occurrence of antimicrobial compounds in Plectranthus amboinicus essential oil was investigated. Thus, this study aims to determine susceptibility of Staphylococcus aureus isolated from food to antibiotics, P. amboinicus essential oil (PAEO) and carvacrol.
METHODS
Leaves and stem of P. amboinicus were used for extraction of essential oil (PAEO) by hydrodistillation technique and EO chemical analysis was performed by gas chromatography coupled to a mass spectrometer. S. aureus strains (n = 35) isolated from food and S. aureus ATCC 6538 were used to evaluate the antimicrobial and antibiofilm activity of PAEO and carvacrol. All strains (n = 35) were submitted to antimicrobial susceptibility profile by disk diffusion method. Determination of MIC and MBC was performed by microdilution technique and antibiofilm activity was determined by microtiter-plate technique with crystal violet assay and counting viable cells in Colony Forming Units (CFU).
RESULTS
Carvacrol (88.17%) was the major component in the PAEO. Antibiotic resistance was detected in 28 S. aureus strains (80%) and 12 strains (34.3%) were oxacillin and vancomycin-resistant (OVRSA). From the 28 resistant strains, 7 (25%) showed resistance plasmid of 12,000 bp. All strains (n = 35) were sensitive to PAEO and carvacrol, with inhibition zones ranging from 16 to 38 mm and 23 to 42 mm, respectively. The lowest MIC (0.25 mg mL) and MBC (0.5 mg mL) values were observed when carvacrol was used against OVRSA. When a 0.5 mg mL concentration of PAEO and carvacrol was used, no viable cells were found on S. aureus biofilm.
CONCLUSION
The antibacterial effect of carvacrol and PAEO proves to be a possible alternative against planktonic forms and staphylococcal biofilm.
Topics: Anti-Bacterial Agents; Biofilms; Cymenes; Drug Resistance, Bacterial; Humans; Monoterpenes; Oils, Volatile; Oxacillin; Plant Extracts; Plant Leaves; Plectranthus; Staphylococcal Infections; Staphylococcus aureus; Vancomycin
PubMed: 28915875
DOI: 10.1186/s12906-017-1968-9 -
Acta Haematologica 1979
Topics: Agranulocytosis; Humans; Oxacillin
PubMed: 105544
DOI: 10.1159/000207629