[Bacterial strains isolated from systemic infections and reported for evaluation and antibiotic resistance surveillance by the "Dr. Victor Babeş" Clinical Hospital for Infectious and Tropical Diseases, Bucharest]

Abstract

Aim: Testing antibiotic resistance of bacterial strains (compulsor, reported for EARSS surveillance) isolated from patients hospitalised for systemic infection in the "Dr. V. Babe" Hospital for Infectious and Tropical Diseases during 01.01.2005-11.11.2009, for a dynamic evaluation and for the surveillance of resistance emergence for certain classes of antibiotics.

Material and methods: Bacterial isolation: BacT/ALERT system; strain identification in classic and automated system (ATB Expression. VITEK 2C): antibioresistance: disk-difussion method (NCCLS 2005--CLSI 2009), MIC (E-Test, ATB/ Expression, VITEK 2C). Screening of ESBL-producing strains performed with double disk-difussion method (DDD). Reference strains used: S. aureus ATCC 25923, S. pneumoniae ATCC 49619, E. coli A TCC 25922, Enterococcus fiecalis ATCC 29212.

Results: During the studied period, 245 bacterial strains have been isolated, identified and tested (Staphylococcus aureus / 70, Streptococcus pneumoniae / 61, Enterococcus faecalis / 18, Enterococcus faecium / 5, Neisseria meningitidis / 18, E. coli / 73). out of 166 hemocultures and 79 cerebrospinal fluids / CSF. The average incidence of MRSA strains in systemic infections was 34.28%. 44.28% of the S. aureus strains were resistant to erythromycin, 17.14% to cyprofloxacyne, 15.71% to rifampicine, 14.49% to gentamycine. No strain resistant to vancomycine and linezolide. Streptococcus pneumoniae presented an average high resistance to penicillin G of 11.47%. and a 1.63% resistance to third generation cephalosporines. 0% resistance to vancomycine and rifampicine. 7/ 18 Enterococcus faecalis strains and 4/5 Enterococcus faecium strains presented high level resistance to gentamycine (CN 120 microg/disk) and no strain was resistant to vancomycine, teicoplanin or linezolid. The 18 Neisseria meningitidis strains were all sensitive to beta-lactams, macrolides, fluoroquinolones and cloramphenicol. For the 73 Escherichia coli strains, the average incidence of ESBL-producing isolates was 10.95%, the average resistance to ampicillin was 58.90%, to gentamycine--13.88% and to cyprofloxacin--20.83%. No strain resistant to carbapenemes and amikacine.

Conclusions: For the systematic surveillance of antibiotic resistance there is a need for a harmonised protocol of data gathering and strain selection and the rigurous implementation of correct evaluating methods for antibiotic resistance in the microbiology laboratory. Carbapenemes. glycopeptides and oxazolidinones still present a major effectiveness in the first intention treatment of systemic infections.