Evaluation of the new VITEK 2 system for determination of the susceptibility of clinical isolates of Streptococcus pneumoniae.
BACKGROUND
The VITEK 2 is a new version of the automated system for organism identification and susceptibility testing. One of the differences between this system and its predecessor, VITEK, is the ability to perform rapid susceptibility testing of Streptococcus pneumoniae. This study compares the results of susceptibility testing of S. pneumoniae using the VITEK 2 system and a commercial microbroth dilution method, Sensititre.


METHODS
A group of 214 clinical isolates of S. pneumoniae were selected to include isolates with previously documented penicillin resistance. The antimicrobial agents tested were benzylpenicillin, cefotaxime, erythromycin, trimethoprim/sulfamethoxazole, tetracycline, chloramphenicol, imipenem and vancomycin.


RESULTS
The best agreement was achieved with vancomycin (100%), erythromycin (95.8%) and tetracycline (95.8%). The lowest level of agreement was found with benzylpenicillin (88.6%) and cefotaxime (90.1%). We observed rates of 12.3 and 15.7% for minor errors with penicillin and cefotaxime, respectively, and 1 very major error for cefotaxime.


CONCLUSIONS
The VITEK 2 allows rapid determination of the antimicrobial susceptibility of S. pneumoniae and demonstrated a good degree of agreement with the Sensititre method for most of the antimicrobials tested.
Chávez
Mónica
M
Servicio de Microbiología Clínica, Hospital Universitario de Valme, Sevilla, Spain.
García López
Jose Luis
JL
Coronilla
Julian
J
Valverde
Anastasio
A
Serrano
M Carmen
MC
Claro
Rosa
R
Martín Mazuelos
Estrella
E
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002439:Cefotaxime / Q000494:pharmacology; D004917:Erythromycin / Q000494:pharmacology; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods*; D010403:Penicillin Resistance; D011008:Pneumococcal Infections / Q000382:microbiology; D013296:Streptococcus pneumoniae / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification*; D013753:Tetracycline Resistance; D020713:Vancomycin Resistance
D000900:Anti-Bacterial Agents; D004917:Erythromycin; D002439:Cefotaxime