Impacto económico de los métodos de diagnóstico rápido en Microbiología Clínica: precio de la prueba o impacto clínico global

Fluorescent optotracers for bacterial and biofilm detection and diagnostics

Effective treatment of bacterial infections requires methods that accurately and quickly identify which antibiotic should be prescribed. This review describes recent research on the development of optotracing methodologies for bacterial and biofilm detection and diagnostics. Optotracers are small, chemically well-defined, anionic fluorescent tracer molecules that detect peptide- and carbohydrate-based biopolymers. This class of organic molecules (luminescent conjugated oligothiophenes) show unique electronic, electrochemical and optical properties originating from the conjugated structure of the compounds. The photophysical properties are further improved as donor-acceptor-donor (D-A-D)-type motifs are incorporated in the conjugated backbone. Optotracers bind their biopolymeric target molecules via electrostatic interactions. Binding alters the optical properties of these tracer molecules, shown as altered absorption and emission spectra, as well as ON-like switch of fluorescence. As the optotracer provides a defined spectral signature for each binding partner, a fingerprint is generated that can be used for identification of the target biopolymer. Alongside their use for in situ experimentation, optotracers have demonstrated excellent use in studies of a number of clinically relevant microbial pathogens. These methods will find widespread use across a variety of communities engaged in reducing the effect of antibiotic resistance. This includes basic researchers studying molecular resistance mechanisms, academia and pharma developing new antimicrobials targeting biofilm infections and tests to diagnose biofilm infections, as well as those developing antibiotic susceptibility tests for biofilm infections (biofilm-AST). By iterating between the microbial world and that of plants, development of the optotracing technology has become a prime example of successful cross-feeding across the boundaries of disciplines. As optotracers offers a capacity to redefine the way we work with polysaccharides in the microbial world as well as with plant biomass, the technology is providing novel outputs desperately needed for global impact of the threat of antimicrobial resistance as well as our strive for a circular bioeconomy.

Real Life Clinical Impact of Antimicrobial Stewardship Actions on the Blood Culture Workflow from a Microbiology Laboratory

BACKGROUND

Accelerating the diagnosis of bacteremia is one of the biggest challenges in clinical microbiology departments. The fast establishment of a correct treatment is determinant on bacteremic patients' outcomes. Our objective was to evaluate the impact of antimicrobial therapy and clinical outcomes of a rapid blood culture workflow protocol in positive blood cultures with Gram-negative bacilli (GNB).

METHODS

A quasi-experimental before-after study was performed with two groups: (i) control group (conventional work-protocol) and (ii) intervention group (rapid workflow-protocol: rapid identification by Matrix-Assisted Laser Desorption/Ionization-Time-Of-Flight (MALDI-TOF) and antimicrobial susceptibility testing (AST) from bacterial pellet without overnight incubation). Patients were divided into different categories according to the type of intervention over treatment. Outcomes were compared between both groups.

RESULTS

A total of 313 patients with GNB-bacteremia were included: 125 patients in the control group and 188 in the intervention. The time from positive blood culture to intervention on antibiotic treatment decreased from 2.0 days in the control group to 1.0 in the intervention group (p < 0.001). On the maintenance of correct empirical treatment, the control group reported 2.0 median days until the clinical decision, while in the intervention group was 1.0 (p < 0.001). In the case of treatment de-escalation, a significant difference between both groups (4.0 vs. 2.0, p < 0.001) was found. A decreasing trend on the change from inappropriate treatments to appropriate ones was observed: 3.5 vs. 1.5; p = 0.12. No significant differences were found between both groups on 7-days mortality or on readmissions in the first 30-days.

CONCLUSIONS

Routine implementation of a rapid workflow protocol anticipates the report of antimicrobial susceptibility testing results in patients with GNB-bacteremia, decreasing the time to effective and optimal antibiotic therapy.

Impact of Sepsis Flow Chip, a novelty fast microbiology method, in the treatment of bacteremia caused by Gram-negative bacilli

Objective

The aim of this study was to assess the impact of the information provided by the new Sepsis Chip Flow system (SFC) and other fast microbiological techniques on the selection of the appropriate antimicrobial treatment by the clinical researchers of an antimicrobial stewardship team.

Methods

Two experienced clinical researchers performed the theoretical exercise of independently selecting the treatment for patients diagnosed by bacteremia due to bacilli gram negative (BGN). At first, the clinicians had only available the clinical characteristics of 74 real patients. Sequentially, information regarding the Gram stain, MALDI-TOF, and SFC from Vitro were provided. Initially, the researchers prescribed an antimicrobial therapy based on the clinical data, later these data were complementing with information from microbiological techniques, and the clinicians made their decisions again.

Results

The data provided by the Gram stain reduced the number of patients prescribed with combined treatments (for clinician 1, from 23 to 7, and for clinician 2, from 28 to 12), but the use of carbapenems remained constant. In line with this, the data obtained by the MALDI-TOF also decreased the combined treatment, and the use of carbapenems remained unchanged. By contrast, the data on antimicrobial resistance provided by the SFC reduced the carbapenems treatment.

Conclusions

From the theoretical model the Gram stain and the MALDI-TOF results achieved a reduction in the combined treatment. However, the new system tested (SFC), due to the resistance mechanism data provided, not only reduced the combined treatment, it also decreased the prescription of the carbapenems.

Fundamentals and implementation of Microbiological Diagnostic Stewardship Programs

Microbiological diagnostic stewardship programs promote coordinated measures aimed at optimizing the use of diagnostic techniques, thus favouring the adoption of adequate and cost-effective therapeutic, clinical and preventive decisions. The implementation of microbiological diagnostic stewardship relies upon the creation of multidisciplinary committees led by clinical microbiologists for the design of diagnostic algorithms, the adequacy of the laboratory computer system to monitor the relevance of the requested diagnostic tests, the implementation of a quality control system, the design and performance of studies of cost-effectiveness, the training of the petitioner and the technical and nursing staff and the continuous evaluation of the program. The incorporation of microbiological diagnostic stewardship in routine care reports tangible benefits for the patient while strengthening the pivotal role of the clinical microbiologist in the management of infectious diseases.