Carriage, Clinical Microbiology and Transmission of Staphylococcus aureus

2016 ◽  
pp. 1-19 ◽  
Author(s):  
Anna Aryee ◽  
Jonathan D. Edgeworth
Keyword(s):  
Staphylococcus Aureus ◽  
Clinical Microbiology

scholarly journals Reduced Production of Bacterial Membrane Vesicles Predicts Mortality in ST45/USA600 Methicillin-Resistant Staphylococcus aureus Bacteremia

Antibiotics ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 2 ◽  
Author(s):  
Somrita Dey ◽  
Smitha Gudipati ◽  
Christopher Giuliano ◽  
Marcus J. Zervos ◽  
Jonathan M. Monk ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Clinical Microbiology ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Membrane Vesicle ◽  
Membrane Vesicles ◽  
Bacterial Membrane ◽  
Staphylococcus Aureus Bacteremia ◽  
Immune Biomarkers ◽  
Microbial Biomarkers

Immune biomarkers can stratify mortality risk in staphylococcal bacteremia. Microbial biomarkers may provide more consistent signals during early infection. We demonstrate that in ST45/USA600 bacteremia, bacterial membrane vesicle production in vitro predicts clinical mortality (773 vs. 116 RFU, survivors vs. decedents, p < 0.0001). Using a threshold of 301 relative fluorescence units (RFU), the sensitivity and specificity of the membrane vesicles to predict mortality are 78% and 90%, respectively. This platform is facile, scalable and can be integrated into clinical microbiology lab workflows.

scholarly journals Evaluation of the antimicrobial susceptibility testing process in clinical microbiology laboratories at Niamey, Niger

2021 ◽  
Vol 22 (4) ◽  
pp. 448-456
Author(s):  
H. Idrissa ◽  
O. Abdoulaye ◽  
A. Yacouba ◽  
D. Alhousseini Maiga ◽  
H. Moumouni Sambo ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Risk Assessment ◽  
Staphylococcus Aureus ◽  
Antimicrobial Susceptibility ◽  
Clinical Microbiology ◽  
Susceptibility Testing ◽  
Antimicrobial Susceptibility Testing ◽  
Critical Control Points ◽  
Criticality Index ◽  
Reference Strains

Background: Risk assessment is the means of identifying and evaluating potential errors or problems that may occur in testing process. The aim of this study was to perform risk assessment of antimicrobial susceptibility testing (AST) process in clinical microbiology laboratories of Niamey, Niger Republic.Methodology: We conducted a descriptive cross-sectional study from October 1 to December 31, 2019, to evaluate AST performance in seven clinical microbiology laboratories at Niamey, the capital city of Niger republic. The evaluation focused on the determination of the criticality index (CI) of each critical point (frequency of occurrence of anomalies, severity of the process anomaly, and detectability of the anomaly during the process) in the AST process and the performance of the AST through an observation sheet using two reference strains; Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 29213.Results: The criticality index (CI) was greater than 6 for most of the critical points related to material, medium, equipment, method and labour for the AST process in all the laboratories. A range of 18-100% errors on the inhibition zone diameters of the reference strains were observed. Major and/or minor categorization (Sensitive S, Intermediate I and Resistance R) discrepancies were found at all the laboratories for either one or both reference strains. The antibiotics most affected by the S/I/R discrepancies were trimethoprim (100%), vancomycin (100%), amoxicillin (80%) and amoxicillin + clavulanic acid (70%).Conclusion: This study showed a deficiency in the control of critical control points that impacts the performance of the AST reported by the laboratories in Niger. Corrective actions are needed to improve the performance of AST in clinical microbiology laboratories in Niger.   French title: Evaluation du processus de réalisation de l’antibiogramme dans les laboratoires d’analyses de biologie médicale de la ville de Niamey, Niger Contexte: L'évaluation des risques est le moyen d'identifier et d'évaluer les erreurs ou les problèmes potentiels qui peuvent survenir dans le processus de test. L'objectif de cette étude était de réaliser une évaluation des risques du processus d'antibiogramme (ABG) dans les laboratoires de microbiologie clinique de Niamey, en République du Niger.Méthodologie: Nous avons mené une étude transversale descriptive du 1er octobre au 31 décembre 2019 pour évaluer la performance des ABG dans sept laboratoires de microbiologie clinique à Niamey, capitale de la république du Niger. L'évaluation a porté sur la détermination de l'indice de criticité (IC) de chaque point critique (fréquence d'apparition des anomalies, gravité de l'anomalie du processus et détectabilité de l'anomalie au cours du processus) dans le processus et la performance des AGB à travers une fiche d'observation en utilisant deux souches de référence; Escherichia coli ATCC 25922 et Staphylococcus aureus ATCC 29213.Résultats: L'indice de criticité était supérieur à 6 pour la plupart des points critiques liés au matériel, au milieu, à l'équipement, à la méthode et à la main-d'oeuvre pour le processus AST dans tous les laboratoires. Une fourchette d'erreurs de 18 à 100% sur les diamètres des zones d'inhibition des souches de référence a été observée. Des écarts de catégorisation majeurs et/ou mineurs (Sensible: S, Intermédiaire: I et Résistance: R) ont été constatés dans tous les laboratoires pour l'une ou les deux souches de référence. Les  antibiotiques les plus touchés par les écarts S/I/R étaient la triméthoprime (100%), la vancomycine (100%), l'amoxicilline (80%) et l'amoxicilline + acide clavulanique (70%).Conclusion: Cette étude a montré une déficience dans le contrôle des points de contrôle critiques qui a un impact sur la performance de l'antibiogramme rapportée par les laboratoires au Niger. Des actions correctives sont nécessaires pour améliorer la performance des ABG dans les laboratoires de microbiologie clinique au Niger.

scholarly journals Transient Silencing of Antibiotic Resistance by Mutation Represents a Significant Potential Source of Unanticipated Therapeutic Failure

mBio ◽  
2019 ◽  
Vol 10 (5) ◽  
Author(s):  
Louise Kime ◽  
Christopher P. Randall ◽  
Frank I. Banda ◽  
Francesc Coll ◽  
John Wright ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Antibiotic Resistance ◽  
Clinical Microbiology ◽  
Pathogenic Bacteria ◽  
Susceptibility Testing ◽  
Genetic Defect ◽  
Antibiotic Resistance Genes ◽  
Clinical Microbiology Laboratory ◽  
Potential Threat ◽  
Content Type

ABSTRACT Sporadic literature reports describe isolates of pathogenic bacteria that harbor an antibiotic resistance determinant but remain susceptible to the corresponding antibiotic as a consequence of a genetic defect. Such strains represent a source from which antibiotic resistance may reemerge to cause treatment failure in patients. Here, we report a systematic investigation into the prevalence and nature of this phenomenon, which we term silencing of antibiotic resistance by mutation (SARM). Instances of SARM were detected among 1,470 Staphylococcus aureus isolates through side-by-side comparison of antibiotic resistance genotype (as determined by whole-genome sequencing) versus phenotype (as assessed through susceptibility testing). Of the isolates analyzed, 152 (10.3%) harbored a silenced resistance gene, including 46 (3.1%) that exhibited SARM to currently deployed antistaphylococcal drugs. SARM resulted from diverse mutational events but most commonly through frameshift mutation of resistance determinants as a result of point deletion in poly(A) tracts. The majority (∼90%) of SARM strains reverted to antibiotic resistance at frequencies of ≥10−9; thus, while appearing antibiotic sensitive in the clinical microbiology laboratory, most S. aureus isolates exhibiting SARM will revert to antibiotic resistance at frequencies achievable in patients. In view of its prevalence in a major pathogen, SARM represents a major potential threat to the therapeutic efficacy of antibiotics. IMPORTANCE Antibiotic resistance hinders the treatment of bacterial infection. To guide effective therapy, clinical microbiology laboratories routinely perform susceptibility testing to determine the antibiotic sensitivity of an infecting pathogen. This approach relies on the assumption that it can reliably distinguish bacteria capable of expressing antibiotic resistance in patients, an idea challenged by the present study. We report that the important human pathogen Staphylococcus aureus frequently carries antibiotic resistance genes that have become inactivated (“silenced”) by mutation, leading strains to appear antibiotic sensitive. However, resistance can rapidly reemerge in most such cases, at frequencies readily achievable in infected patients. Silent antibiotic resistance is therefore prevalent, transient, and evades routine detection, rendering it a major potential threat to antibacterial chemotherapy.

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