gms | German Medical Science

Objectives: ESBL producing E.coli strains become a serious problem, as these strains often leave little therapeutic options especially in intensive care units. The therapeutic options seem further limited if the former EUCAST expert rule was used to convert sensitivity to beta lactams to intermediate and intermediate to beta lactams to resistant, if an ESBL was recorded for the respective strain. The change for 2010 is: “Cephalosporin breakpoints for Enterobacteriaceae will detect clinically important resistance mechanisms (including ESBL). Some strains that produce beta-lactamases are susceptible or intermediate to 3rd or 4th generation cephalosporins with these breakpoints and should be reported as found, i.e. the presence or absence of an ESBL does not in itself influence the categorization of susceptibility.”

We analysed isolates in order to see if the change in the EUCAST expert rule opens new therapeutic options.

Methods: The laboratory used the automated BD PHOENIX-systems measuring MICs. The BD EPICENTER Data-Management-System is used for the evaluation of the data in the laboratory and for the transfer of the data for joint analysis. For this study we analysed the MICs of ESBL producing E.coli isolates in a period from 2006 to 2010. The ESBL production was checked with the associated BD-expert system, as the Phoenix shows excellent performance as far as the ESBL detection is concerned [1].

Copy strains are excluded. Quality control assays are routinely performed.

Results: With the MICs of the ESBL producing strains to ceftazidime (CAZ), cefotaxime (CTX), cefepime (FMC), and Azthreonam (ATM) we calculated the sensitivity, using the new EUCAST breakpoints (Table 1 [Tab. 1], Table 2 [Tab. 2]).

Conclusion: There is no doubt, that the knowledge of the underlying mechanism is of great value for epidemiological and infection control reasons. However in the every day routine laboratory, and in favour of the patient the new breakpoins together with a reliable system for the detection of ESBLs is beneficial for the patient, as it opens treatment alternatives and at the same time gives a warning for the infection control.