Calderwood S A, Wennersten C, Moellering R C, Kunz L J, Krogstad D J
Antimicrob Agents Chemother. 1977 Sep;12(3):401-5. doi: 10.1128/AAC.12.3.401.
Two hundred and three recent clinical isolates of enterococci were tested for susceptibility to streptomycin, kanamycin, amikacin, gentamicin, sisomicin, and tobramycin. Depending upon the source of the isolate, 36 to 54% of the enterococci demonstrated high-level resistance (minimal inhibitory concentration, >2,000 mug/ml) to streptomycin, 16 to 49% to kanamycin, and 0 to 14% to amikacin. None of the strains was highly resistant to gentamicin, sisomicin, or tobramycin. A comparison with isolates of enterococci obtained in 1968 revealed that there has been a decrease in prevalence of high-level resistance among organisms isolated from wound cultures in 1976. However, no decrease in resistance to streptomycin or kanamycin was demonstrated among blood or urine isolates. Penicillin, combined with gentamicin, sisomicin, or tobramycin, was synergistic against all 10 strains of Streptococcus faecalis subjected to formal testing. For streptomycin and kanamycin, the presence or absence of synergism with penicillin correlated with the absence or presence of high-level aminoglycoside resistance. High-level resistance to amikacin was seen in only 1 of the 10 strains. Nonetheless, combinations of penicillin plus amikacin failed to produce synergistic killing against 6 of the 10 strains. Indeed, the combination was synergistic only against those four strains that were susceptible to high levels of kanamycin.
对203株近期分离的肠球菌进行了链霉素、卡那霉素、阿米卡星、庆大霉素、西索米星和妥布霉素的药敏试验。根据分离菌株的来源，36%至54%的肠球菌对链霉素表现出高水平耐药（最低抑菌浓度，>2000μg/ml），16%至49%对卡那霉素耐药，0至14%对阿米卡星耐药。没有菌株对庆大霉素、西索米星或妥布霉素高度耐药。与1968年获得的肠球菌分离株相比，结果显示1976年从伤口培养物中分离出的菌株中高水平耐药的流行率有所下降。然而，血液或尿液分离株对链霉素或卡那霉素的耐药性没有下降。青霉素与庆大霉素、西索米星或妥布霉素联合使用时，对所有10株接受正式试验的粪链球菌均具有协同作用。对于链霉素和卡那霉素，与青霉素的协同作用与否与高水平氨基糖苷类耐药性的有无相关。10株菌株中只有1株对阿米卡星表现出高水平耐药。尽管如此，青霉素加阿米卡星的组合对10株菌株中的6株未能产生协同杀菌作用。事实上，该组合仅对那些对高水平卡那霉素敏感的4株菌株具有协同作用。
