Microbiology

The Microbiology department has sophisticated instruments for the automatic recognition of bacterial species, and management software which is continuously updated on the basis of ongoing taxonomic discoveries and reclassifications in the microbiological field and the modern, reasoned use of antibiotic treatment. The antibiogram is a complex test that enables us to determine the profile of sensitivity to the molecules tested, by exposing an isolated bacterium to varying concentrations of different antibiotics. The method used by MyLav is automated broth microdilution using fully automated instruments that minimise operator error. This method makes it possible to obtain the minimal inhibitory concentration (MIC) for the various molecules tested. This is the lowest concentration of the drug that will inhibit in vitro growth of the micro-organism tested. The MICs are then compared with threshold values (breakpoints) set by a number of scientific institutions for the various microorganism-antibiotic combinations. The results obtained in vitro make it possible to place the bacteria identified in relation to the molecules tested into 3 categories or classes of sensitivity: S, R, and I, where S is predictive of drug efficacy, R indicates unlikely efficacy and advises against its use in therapy, while I expresses a low sensitivity, which assumes that the drug may be effective in vivo provided it can reach adequate concentrations at the site of infection. If the antibiogram is correctly performed according to international guidelines, it also helps microbiologists (and the automated expert system) to correctly identify the bacterial phenotype by recognising so-called ‘impossible susceptibility profiles’, which therefore rules out certain operator choices. It also enables us to effectively combat bacterial resistance by differentiating constitutional resistance factors from acquired ones and by identifying wild strains and so-called epidemiological cut-offs. The appropriate use of the antibiotic molecules tested in different antibiogram galleries also helps make the correct therapeutic choice according to the principle of equivalent molecules.
In the case of its own antibiograms, MyLav has adopted the guidelines dictated by EUCAST (European Committee on Antimicrobial Susceptibility Testing) and CLSI (Clinical and Laboratory Standard Institute)

Equipment currently used
N. 1 BIOMERIEUX VITEK 2 XL 120 microbiology system;
N. 1 Biomerieux VITEK – MS mass spectrometer with MALDI-TOF method
N. 1 Biohazardcat laminar flow hood. One type A EUROCLONE.
N. 1 37 °C thermostat
N. 1 30-40 °C thermostat
N. 2 anaerobic jars;
N. 2 jars for microaerophilia;
N. 1 NIKON 80i ECLIPSE Microscope.