-
Journal of Clinical Microbiology Nov 2021The Clinical and Laboratory Standards Institute (CLSI) Subcommittee on Antimicrobial Susceptibility Testing (AST) develops and publishes standards and guidelines for AST... (Review)
Review
The Clinical and Laboratory Standards Institute (CLSI) Subcommittee on Antimicrobial Susceptibility Testing (AST) develops and publishes standards and guidelines for AST methods and results interpretation in an annual update to the (M100). This minireview will discuss changes to M100 for the 31st edition, including new and revised breakpoints and testing recommendations. New MIC and disk diffusion breakpoints are described for azithromycin ( spp.), imipenem-relebactam (, Pseudomonas aeruginosa, and anaerobes), and lefamulin (Staphylococcus aureus, Haemophilus influenzae, and Streptococcus pneumoniae), and disk breakpoints are described for azithromycin and Neisseria gonorrhoeae. The rationale behind revised oxacillin MIC breakpoints for select staphylococci is discussed. Updates to test methods include a method for disk diffusion using positive blood culture broth and use of linezolid to predict tedizolid susceptibility. There is clarification on which drugs to suppress on bacteria isolated from the cerebrospinal fluid and clarification on the use of a caret symbol attached to the intermediate category ("I^") to indicate those antimicrobials that concentrate in the urine.
Topics: Anti-Bacterial Agents; Humans; Laboratories; Microbial Sensitivity Tests; Oxacillin; Pseudomonas aeruginosa
PubMed: 34550809
DOI: 10.1128/JCM.00213-21 -
BMC Microbiology Nov 2019Probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit on the host, are now accepted as suitable alternatives to...
BACKGROUND
Probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit on the host, are now accepted as suitable alternatives to antibiotics in the control of animal infections and improving animal production. Lactic acid bacteria (LAB) with remarkable functional properties have been evaluated in different studies as possible probiotic candidates. The purpose of this study was to isolate, characterize and assess the potentials of LAB from poultry gastrointestinal tract as potential poultry probiotics.
RESULTS
Potential LAB probiotics were isolated from broilers, characterized and evaluated for probiotic properties including antagonistic activity (against Escherichia coli, E. coli O157: H7, Enterococcus faecalis, Salmonella Typhimurium, S. Enteritidis and Listeria monocytogenes), survivability in simulated gastric juice, tolerance to phenol and bile salts, adhesion to ileum epithelial cells, auto and co-aggregation, hydrophobicity, α-glucosidase inhibitory activity, and antibiotic susceptibility tests. Most promising LAB strains with excellent probiotic potentials were identified by API 50 CHL and 16S rRNA sequencing as Lactobacillus reuteri I2, Pediococcus acidilactici I5, P. acidilactici I8, P. acidilactici c3, P. pentosaceus I13, and Enterococcus faecium c14. They inhibited all the pathogens tested with zones of inhibition ranging from 12.5 ± 0.71 to 20 ± 0 mm, and competitively excluded (P < 0.05) the pathogens examined while adhering to ileum epithelial cells with viable counts of 3.0 to 6.0 Log CFU/ml. The selected LAB strains also showed significant (P < 0.005) auto and co-aggregation abilities with α-glucosidase inhibitory activity ranging from 12.5 to 92.0%. The antibiotic susceptibility test showed 100.00% resistance of the LAB strains to oxacillin, with multiple antibiotic resistance indices above 0.5.
CONCLUSION
The selected LAB strains are ideal probiotic candidates which can be applied in the field for the improvement of poultry performance and control of pathogens in poultry, hence curtailing further transmission to humans.
Topics: Animals; Chickens; DNA, Ribosomal; Drug Resistance, Bacterial; Gastric Juice; Gastrointestinal Tract; Lactobacillales; Microbial Viability; Oxacillin; Poultry; Probiotics; RNA, Ribosomal, 16S; Sequence Analysis, DNA
PubMed: 31718570
DOI: 10.1186/s12866-019-1626-0 -
Journal of Clinical Microbiology Jan 2022Evaluation of penicillin and oxacillin susceptibility testing was conducted on 200 Staphylococcus lugdunensis isolates. Disc diffusion with penicillin 1 IU (P1, EUCAST)...
Evaluation of penicillin and oxacillin susceptibility testing was conducted on 200 Staphylococcus lugdunensis isolates. Disc diffusion with penicillin 1 IU (P1, EUCAST) and penicillin 10 IU (P10, CLSI) was compared with nitrocefin discs (Cefinase) and automated broth microdilution (Vitek 2). Oxacillin susceptibility was extrapolated from cefoxitin (FOX; 30 μg) disc diffusion and compared with Vitek 2 results. The reference methods were and PCR. Penicillin zone diameter and zone edge correlated with PCR results in all except two P10-susceptible isolates (very major error [VME]) and one P1-resistant isolate (major error [ME]). A total of 148 isolates were negative, of which 146 and 149 isolates were susceptible by P1 and P10, respectively. A total of 127 were penicillin susceptible by Vitek 2. Vitek 2 overcalled resistance in 21 -negative, 20 P1-susceptible, and 22 P10-susceptible isolates (Vitek 2 ME rate, 14.2%). Two -positive isolates were oxacillin resistant by FOX disc and Vitek 2 methods (categorical agreement). However, 18 FOX-susceptible -negative isolates tested resistant by Vitek 2. In conclusion, Vitek 2 overestimated penicillin and oxacillin resistance compared with disc diffusion and PCR results. In our study, disc diffusion with zone edge interpretation was more accurate and specific than automated broth microdilution for S. lugdunensis.
Topics: Anti-Bacterial Agents; Anti-Infective Agents; Bacterial Proteins; Humans; Microbial Sensitivity Tests; Oxacillin; Staphylococcal Infections; Staphylococcus lugdunensis
PubMed: 34705537
DOI: 10.1128/JCM.03202-20 -
Revista Argentina de Microbiologia 2022The aim of this study was to characterize phenotypically and genotypically 27 mecA positive Staphylococcus aureus strains with oxacillin MICs of ≤2μg/ml by Vitek 2,...
The aim of this study was to characterize phenotypically and genotypically 27 mecA positive Staphylococcus aureus strains with oxacillin MICs of ≤2μg/ml by Vitek 2, isolated in different regions of Uruguay. Susceptibility to oxacillin and cefoxitin was studied by gradient diffusion, disk diffusion to cefoxitin, and Phoenix and MicroScan systems. PBP2a was determined. SCCmec typing was performed and the isolates were compared by PFGE. Twenty-six isolates were susceptible to oxacillin; one strain was susceptible to cefoxitin by disk diffusion and 3 strains by gradient diffusion. Phoenix and MicroScan panels detected methicillin resistance in 25 and 27 strains, respectively. Twenty-six strains tested positive for PBP2a. Twenty-six strains carried SCCmec V and 24 belonged to pulsotype A. One strain carried SCCmec IV and did not belong to pulsotype A. Cefoxitin disk diffusion test and PBP2a detection correctly identified 26 of these 27 strains as MRSA. PFGE results suggest the dissemination of a cluster of MRSA carrying SCCmec V.
Topics: Humans; Oxacillin; Staphylococcus aureus; Cefoxitin; Uruguay; Anti-Bacterial Agents; Bacterial Proteins; Staphylococcal Infections; Microbial Sensitivity Tests; Methicillin-Resistant Staphylococcus aureus
PubMed: 35725665
DOI: 10.1016/j.ram.2022.05.004 -
The Journal of Antimicrobial... Nov 2022Anti-staphylococcal penicillins (ASPs) are among the most commonly prescribed antibiotics in children and are associated with a risk of drug-induced liver injury (DILI).... (Review)
Review
INTRODUCTION
Anti-staphylococcal penicillins (ASPs) are among the most commonly prescribed antibiotics in children and are associated with a risk of drug-induced liver injury (DILI). Despite the frequent use of ASPs in children, there is no consensus on whether liver function tests (LFTs) should be routinely monitored during treatment.
OBJECTIVES
To review the literature on the frequency of ASP-related DILI in children to determine the incidence, risk factors and outcomes of hepatotoxicity.
METHODS
PubMed, MEDLINE and Embase were searched in January 2022 for original studies of children who received cloxacillin, dicloxacillin, flucloxacillin, methicillin, nafcillin or oxacillin that included ≥10 children aged up to 18 years, and presented data on the incidence of DILI in children exposed to ASPs.
RESULTS
Overall, two studies of oral flucloxacillin, two of intravenous (IV) methicillin, three of IV nafcillin and four of IV oxacillin were included. The mean onset of DILI ranged between 7.0 and 19.0 days following commencement of antibiotic treatment and all episodes resolved between 14.2 and 16.0 days after drug discontinuation, with no specific treatment required. This review found that the incidence of DILI in children was 1 in 50 000 for oral flucloxacillin and ranged from 1 in 3 to 13 for IV oxacillin, methicillin and nafcillin.
CONCLUSIONS
This review found that routine LFT monitoring is not required in children receiving low dose oral flucloxacillin in a primary care setting, although pharmacovigilance is critical. For IV preparations, the existing data support routine LFT monitoring in those receiving treatment for at least 7 days.
Topics: Child; Humans; Nafcillin; Methicillin; Penicillins; Floxacillin; Oxacillin; Cloxacillin; Anti-Bacterial Agents; Chemical and Drug Induced Liver Injury
PubMed: 36203386
DOI: 10.1093/jac/dkac325 -
International Journal of Molecular... Apr 2023Methicillin-resistant (MRSA) is responsible for skin and soft tissue infections with multi-resistance to many antibiotics. It is thus imperative to explore alternative...
Methicillin-resistant (MRSA) is responsible for skin and soft tissue infections with multi-resistance to many antibiotics. It is thus imperative to explore alternative antimicrobial treatments to ensure future treatment options. Nisin (NIS), an antibacterial peptide produced by , was selected to combine with Oxacillin (OX), to evaluate the antimicrobial effect and potential mechanism against MRSA. The synergistic antimicrobial effect of OX and NIS was verified by Minimal Inhibitory Concentration (MIC) assays, checkerboard analysis, time-kill curve, biofilm producing ability, and mice skin infection model in vivo. For the potential synergistic antimicrobial mechanism, the microstructure and integrity change of MRSA cells were determined by Scanning and Transmission Electron Microscope (SEM and TEM), intracellular alkaline phosphatase activity and propidium iodide staining were assayed; And transcription of , main gene of MRSA resistant to OX, were detected by qRT-PCR. The results showed NIS could restore the sensitivity of MRSA to OX and inhibit biofilm production; OX + NIS can make MRSA cell deform; NIS may recover OX sensitivity by inhibiting the transcription of . In vivo, mice skin infection models indicate that OX + NIS can substantially alleviate MRSA infections. As a safe commercially available biological compound, NIS and the combination of antibiotics are worth developing as new anti-MRSA biomaterials.
Topics: Animals; Mice; Oxacillin; Methicillin-Resistant Staphylococcus aureus; Nisin; Anti-Bacterial Agents; Anti-Infective Agents; Microbial Sensitivity Tests; Drug Synergism
PubMed: 37047670
DOI: 10.3390/ijms24076697 -
The Lancet. Planetary Health Apr 2023Antimicrobial resistance (AMR) is a pressing, holistic, and multisectoral challenge facing contemporary global health. In this study we assessed the associations between...
BACKGROUND
Antimicrobial resistance (AMR) is a pressing, holistic, and multisectoral challenge facing contemporary global health. In this study we assessed the associations between socioeconomic, anthropogenic, and environmental indicators and country-level rates of AMR in humans and food-producing animals.
METHODS
In this modelling study, we obtained data on Carbapenem-resistant Acinetobacter baumanii and Pseudomonas aeruginosa, third generation cephalosporins-resistant Escherichia coli and Klebsiella pneumoniae, oxacillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecium AMR in humans and food-producing animals from publicly available sources, including WHO, World Bank, and Center for Disease Dynamics Economics and Policy. AMR in food-producing animals presented a combined prevalence of AMR exposure in cattle, pigs, and chickens. We used multivariable β regression models to determine the adjusted association between human and food-producing animal AMR rates and an array of ecological country-level indicators. Human AMR rates were classified according to the WHO priority pathogens list and antibiotic-bacterium pairs.
FINDINGS
Significant associations were identified between animal antimicrobial consumption and AMR in food-producing animals (OR 1·05 [95% CI 1·01-1·10]; p=0·013), and between human antimicrobial consumption and AMR specifically in WHO critical priority (1·06 [1·00-1·12]; p=0·035) and high priority (1·22 [1·09-1·37]; p<0·0001) pathogens. Bidirectional associations were also found: animal antibiotic consumption was positively linked with resistance in critical priority human pathogens (1·07 [1·01-1·13]; p=0·020) and human antibiotic consumption was positively linked with animal AMR (1·05 [1·01-1·09]; p=0·010). Carbapenem-resistant Acinetobacter baumanii, third generation cephalosporins-resistant Escherichia coli, and oxacillin-resistant Staphylococcus aureus all had significant associations with animal antibiotic consumption. Analyses also suggested significant roles of socioeconomics, including governance on AMR rates in humans and animals.
INTERPRETATION
Reduced rates of antibiotic consumption alone will not be sufficient to combat the rising worldwide prevalence of AMR. Control methods should focus on poverty reduction and aim to prevent AMR transmission across different One Health domains while accounting for domain-specific risk factors. The levelling up of livestock surveillance systems to better match those reporting on human AMR, and, strengthening all surveillance efforts, particularly in low-income and middle-income countries, are pressing priorities.
FUNDING
None.
Topics: Humans; Animals; Cattle; Swine; Methicillin-Resistant Staphylococcus aureus; Drug Resistance, Bacterial; Chickens; Anti-Bacterial Agents; Carbapenems; Escherichia coli; Cephalosporins; Oxacillin
PubMed: 37019570
DOI: 10.1016/S2542-5196(23)00026-8 -
Microbiology Spectrum Jun 2022The oxacillin- and cefoxitin-susceptible -positive Staphylococcus aureus is a novel "stealth" methicillin-resistant S. aureus (MRSA) type. Here, we sequenced the whole...
The oxacillin- and cefoxitin-susceptible -positive Staphylococcus aureus is a novel "stealth" methicillin-resistant S. aureus (MRSA) type. Here, we sequenced the whole genome of two oxacillin- and cefoxitin-susceptible -positive MRSA isolates from breast abscesses in a lactating woman and a nasal swab of a healthy student in Guangzhou for investigating the mechanism underlying its occurrence. The reversion of these isolates was selected by exposure to sub-MICs of cefoxitin with or without mupirocin. The expression of both parental strains and their revertants was determined, and the whole genome of the revertants was sequenced. Comparative whole-genome analyses performed for both strains revealed that of the clinical strain was mutated by a single-bp insertion at the 262nd position in the tandem repeat region of the gene, and this mutation that led to the formation of a premature stop codon. The colonizing strain was mutated by a novel G-to-A base substitution in the second promoter region (-35 bp) of . The expression level of strain 697 revertant was 37 times higher than that of the parental strain. Although the expression level was even higher for parental strain 199 compared with that for its revertant, its cDNA sequence contained a single-bp insertion. Collectively, both the missense and single substitution mutations of the second promoter of could render MRSA isolates as "stealth" MRSA, thereby emphasizing the importance of combining phenotype tests with or penicillin-binding protein 2a detection for the identification of MRSA. The oxacillin- and cefoxitin-susceptible -positive Staphylococcus aureus is a novel type of "stealth" methicillin-resistant S. aureus (MRSA), which is difficult to be detected using conventional methods. To investigate the genomic basis of their occurrence, we sequenced the whole genome of two previously recovered oxacillin- and cefoxitin-susceptible -positive MRSA isolates from breast abscesses in a lactating woman and a nasal swab of a healthy student in Guangzhou. Complete SCC structure was absent except for in clinical isolate 199. Additionally, a novel single-base pair insertion was observed in the clinical strain, which resulted in premature termination and a frameshift mutation. The colonizing isolate 697 had a Scc--type IVa, and the second promoter region (-35 bp) of was mutated by a novel G-to-A base substitution. The reversion of oxacillin- and cefoxitin-susceptible -positive S. aureus to resistant MRSA isolates was selected by exposure to subminimum inhibitory cefoxitin with or without mupirocin.
Topics: Abscess; Anti-Bacterial Agents; Bacterial Proteins; Cefoxitin; Female; Genomics; Humans; Lactation; Methicillin-Resistant Staphylococcus aureus; Microbial Sensitivity Tests; Mupirocin; Oxacillin; Penicillin-Binding Proteins; Staphylococcal Infections; Staphylococcus aureus
PubMed: 35608351
DOI: 10.1128/spectrum.00291-22 -
Journal of Applied Microbiology Aug 2022To investigate the priming effects of sub-inhibitory concentrations of biocides on antibiotic resistance in bacteria.
AIMS
To investigate the priming effects of sub-inhibitory concentrations of biocides on antibiotic resistance in bacteria.
METHODS AND RESULTS
Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus were exposed to sub-inhibitory concentrations of biocides via a gradient plate method. Minimum inhibitory concentration (MIC) and antibiotic susceptibility were determined, and efflux pump inhibitors (thioridazine and chlorpromazine) were used to investigate antibiotic resistance mechanism(s). Escherichia coli displayed a twofold increase in MIC (32-64 mg l ) to H O which was stable after 15 passages, but lost after 6 weeks, and P. aeruginosa displayed a twofold increase in MIC (64-128 mg l ) to BZK which was also stable for 15 passages. There were no other tolerances observed to biocides in E. coli, P. aeruginosa or S. aureus; however, stable cross-resistance to antibiotics was observed in the absence of a stable increased tolerance to biocides. Sixfold increases in MIC to cephalothin and fourfold to ceftriaxone and ampicillin were observed in hydrogen peroxide primed E. coli. Chlorhexidine primed S. aureus showed a fourfold increase in MIC to oxacillin, and glutaraldehyde-primed P. aeruginosa showed fourfold (sulphatriad) and eightfold (ciprofloxacin) increases in MIC. Thioridazine increased the susceptibility of E. coli to cephalothin and cefoxitin by fourfold and twofold, respectively, and both thioridazine and chlorpromazine increased the susceptibility S. aureus to oxacillin by eightfold and fourfold, respectively.
CONCLUSIONS
These findings demonstrate that sub-inhibitory concentrations of biocides can prime bacteria to become resistant to antibiotics even in the absence of stable biocide tolerance and suggests activation of efflux mechanisms may be a contributory factor.
SIGNIFICANCE AND IMPACT OF THE STUDY
This study demonstrates the effects of low-level exposure of biocides (priming) on antibiotic resistance even in the absence of obvious increased biocidal tolerance.
Topics: Anti-Bacterial Agents; Cephalothin; Chlorpromazine; Disinfectants; Drug Resistance, Bacterial; Escherichia coli; Microbial Sensitivity Tests; Oxacillin; Pseudomonas aeruginosa; Staphylococcus aureus; Thioridazine
PubMed: 35384175
DOI: 10.1111/jam.15564 -
Journal of Clinical Microbiology Dec 2019Methicillin (β-lactam) resistance in is mediated by the gene, with resistance reported to be as high as 90%. The goal of this study was to evaluate oxacillin and...
Evaluation of Oxacillin and Cefoxitin Disk Diffusion and Microbroth Dilution Methods for Detecting -Mediated β-Lactam Resistance in Contemporary Staphylococcus epidermidis Isolates.
Methicillin (β-lactam) resistance in is mediated by the gene, with resistance reported to be as high as 90%. The goal of this study was to evaluate oxacillin and cefoxitin disk diffusion (DD) and broth microdilution (BMD) methods for the detection of -mediated β-lactam resistance in 100 human isolates of (48 -positive isolates and 52 negative isolates). Oxacillin DD tests using the Clinical and Laboratory Standards Institute (CLSI) M100-S28 breakpoints for / accurately differentiated -positive and -negative isolates, with categorical agreement (CA) of 100% and no very major errors (VMEs) or major errors (MEs) identified. Likewise, oxacillin BMD and cefoxitin DD tests using the coagulase-negative species (CoNS) breakpoints were highly reliable for detecting -mediated β-lactam resistance in isolates. For cefoxitin DD and BMD results interpreted using / breakpoints, the CA was 97.6% and 96.2%, respectively. There were 4.9% VMEs for cefoxitin DD with 0% MEs, and 3.6% VMEs and 3.9% MEs for cefoxitin BMD. Oxacillin BMD using / breakpoints yielded the highest VMEs at 17.4% and 90% CA. Our findings demonstrate that oxacillin DD tests using the CLSI M100-S28 breakpoints for / and oxacillin BMD and cefoxitin DD tests using the CoNS breakpoints reliably identified -mediated β-lactam resistance in Using PCR as the gold standard, the PBP2a SA culture colony test (Abbott Diagnostics) exhibited 100% sensitivity and specificity whereas 2 false negatives were identified using the PBP2' latex agglutination test kit (Thermo Fisher Scientific) with sensitivity and specificity of 95.8% and 100%, respectively.
Topics: Anti-Bacterial Agents; Bacterial Proteins; Cefoxitin; Humans; Microbial Sensitivity Tests; Oxacillin; Polymerase Chain Reaction; Sensitivity and Specificity; Staphylococcal Infections; Staphylococcus epidermidis; beta-Lactam Resistance
PubMed: 31462553
DOI: 10.1128/JCM.00961-19