[Optimization of incubation duration of culture media in microbiology]. / Optimisation des durées d'incubation des milieux de culture en microbiologie.

In order to perform biological analysis, clinical laboratories apply the instructions of reagent suppliers. For culture media these instructions are often incomplete and poorly adapted to the variety of clinical samples and micro-organisms. The REMIC can help to overcome these shortcomings. Required time of incubation for culture media are proposed based on the nature of the sample and the type of micro-organism suspected. Nevertheless, they are most often expressed in multiple of 24 hours and they are often considered as minimal by the laboratories. As the samples are inoculated "continuously", while the readings are most often done at a single definite time of the day, we propose a strategy to optimize incubation duration of cultures medium. A time of incubation in the day so-called "limit" is defined. From this, the incubations are stopped or prolonged according to the results of the culture and the direct examination. As the instructions of suppliers of culture media are not adapted, it appears necessary that these suppliers relies on the repositories of professional societies as this is the case for agars medias used for antibiotic susceptibility testing.

[Contribution and evolution of blood culture quality indicators]. / Apports et perspectives d'évolution des indicateurs qualité de l'hémoculture.

The monitoring of quality indicators, combined with a detailed risk analysis, validates the process of automated blood culture. Here we report the methodology of 5 years monitoring for 5 indicators at the Biology Department of Foch Hospital: volume sampled, proportion of contaminants, proportion of positive blood cultures in each instrument and drawer, epidemiological indicator and proportion of false-positive instrument signals. The results obtained were outside the expected target for the volume sampled and were acceptable for the other indicators. The analysis of these results leads us to discuss the evolution of quality indicators and more particularly the implementation of corrective measures, their periodicity, their relevance as well as the need to refine their results to carry out targeted actions.

Rapid identification of Escherichia coli colonies from clinical sample inoculated on CHROMagar Orientation media (Becton Dickinson).

CHROMmagar Orientation media (Becton Dickinson) was developed and validated for the culture of urinary samples. It allows a direct identification of E. coli colonies without additional tests. As CHROMmagar Orientation media is superior to non-chromogenic media for the distinction of enterobacterial colonies, it is used for the inoculation of a large variety of samples in clinical laboratories. Direct identification of E. coli colonies cultured from these samples is not validated by the manufacturer. The difference in microbial ecology and the nature of the sample may impact CHROMagar Orientation performances for this use. We evaluated these media for the direct identification of E. coli colonies from 410 samples (excluding urine). Its sensitivity of 99% allows a direct identification of E. coli colonies cultured from a wide variety of samples. On-site testing using a large number of representative samples, allows laboratories to assess agar media performance and adapt their uses. Suppliers who are aware of frequent and non-recommended use of their culture media should perform tests and if conclusive, adapt their technical instructions.

[Evaluation of the environmental contamination in microbiology Which strategy to adopt?] / Évaluation de la contamination environnementale en microbiologie Quelle stratégie adopter ?

The culture of micro-organisms exposes to the risk of microbiological contamination at all stages of the analysis: inoculation on culture media, incubation, and observation of cultures. During our accreditation renewal audit, a surveillance point was notified, regarding the lack of consideration of the risk of microbiological contamination. Its mastery mainly relies on cleaning/disinfection operations and their traceability. In addition, several strategies based on environmental sampling or indicators can be performed. We propose a risk analysis in order to present these strategies.