Avaliaçäo do sistema semi-automatizado microscan para identificaçäo de testes de sensibilidade de amostras de enterococos / Evaluation of the microscan semi-automated system for species identification and susceptibility testing of enterococci

O objetivo deste estudo foi avaliar a acurácia de um sistema semi-automatizados, os painéis convencionais MicroScan Positive Breakpoint Combo Type 6 (Dade MicroScan Inc., West Sacramento, CA), para identificaçäo de espécie, avaliaçäo da sensibilidade à vancomicina e à ampicilina e detecçäo de alto grau de resistência à gentamicina (HLRGN) e à estreptomicina (HLRST). Esse método foi comparado com a identificaçäo bioquímica convencional e com o método de diluiçäo em ágar (DA) para avaliaçäo de sensibilidade a antimicrobianos. Dentre as 211 amostras testadas (184 E.faecalis, 21 E.faecium e 6 näo-faecalis-näo-faecium), 95 por cento dos E.faecalis e 67 por cento dos E.faecium foram idetificados corretamente pelo MicroScan. O microScan apresentou 99,5 por cento de concordância com o método de DA para testes de sensibilidade à vancomicina e o HLRGN e o HLRST foi detectado em 92 por cento (33/36) e 84 por cento (31/37) das amostras, respectivamente. Os resultados do presente estudo mostram que este método semi-automatizado apresenta dificuldades na identificaçäo de espécies diferentes de E.faecalis, além de elevadas taxas de erros muito graves para ampicilina (11 por cento), gentamicina (8 por cento) e estreptomicina (16 por cento)

In vitro antimicrobial activity against enterococci isolated in a university hospital in Säo Paulo, Brazil

The prevalence of multiresistant enterococci (MRE) is rapidly increasing and becoming an important problem in several countries. Säo Paulo Hospital is a 600-bed tertiary hospital located in Säo Paulo, Brazil. The use of vancomycin is very high in the hospital due to the high prevalence of multi-resistant S. aureus (around 70 percent). We susceptibillity tested 250 isolates were of Enterococci consecutively collected between March, 1994 and june, 1995. Isolates were susceptibility tested using agar dilution disc diffusion BHI screen plating, and E. test. In addition to vancomycin and teicoplanin, the isolates were tested against amplicillin, gentamicin, streptomycin and RP 59-500. Methods used for susceptibility testing were compared. None of the isolates showed high-level resistence to vancomycin or teicoplanin. The MIC9Os for teicoplanin were menor igual que 1µg/mL for E. faecalis (EF,n-216), E. faecium (EFM,n=23) and for the non-faecalis-non-faecium (NFNF,n=11) species. The MIC90s for vancomycin were 2µg/mL, 4µg/mL and 4µg/mL for EF, EFM and NFNF respectively. Eight isolates (3.2 percent), 5 E. faecalis, 2 E. caseliflavus and 1 E. gallinarum presented intermediate MICs for vancomycin (6 - 12µg/mL), but they were highly susceptible to teicoplanin (MIC0.19 - 1µg/mL). The percentage of resistence to amplicillin and high-level resistence to gentamicin and streptomycin were, respectively: 4.8 percent, 26.4 percent, and 24.8 percent. In spite of the high usage of vancomycin in our hospital, the prevalence of glycopeptide resistence among enterococci seems to be low. Teicoplanin appears to be more potent than vancomycin, RP59-500, gentamicin, streptomycin and amplicillin against this genus, especially EFM and NFNF species.