Mutant Prevention Concentration of Polymyxin B for the Clinical Isolates of Pseudomonas aeruginosa

국문 초록 (Abstract)

배 경 : 최근 항생제에 다제내성을 갖는 Pseudomonas나 Acinetobacter와 같은 그람 음성균들의 빈도가 증가하고 있다. 이로 인해 신장독성 등으로 인해 사용이 제한되었던 polymyxin이 이런 균주의 감염 치료를 위해 다시 사용되고 있다. 이에 본 저자들은 임상적으로 검출되는 Pseudomonas aeruginosa의 polymyxin B에 대한 Mutant prevention concentration (MPC), 돌연변이체빈도(mutant frequency)를 측정하고자 하였다.
재료 및 방법 : 2000년도에 단국대학병원과 서울대학병원에서 검출된 29개의 P. aeruginosa에 대하여 항균제감수성시험, 최저억제농도(MIC) 및 ciprofloxacin과 polymyxin B에 대한 MPC와 돌연변이체빈도를 구하였다.
결 과 : P. aeruginosa의 polymyxin B에 대한 MIC50과 MIC90은 각각 2 ug/mL, 2 ug/mL였고 ciprofloxacin은 0.5 ug/mL, 4 ug/mL이었다. 29개의 균주 중에서 13개가 내성을 보였고 polymyxin B에 대한 MPC50과 MPC90은 각각 32 ug/mL, 64 ug/mL였고, Ciprofloxacin에 대해서는 4 ug/mL, 64 ug/mL였다. 돌연변이체빈도는 polymyxin B에 대해서는 2×10-9에서 2×10-7였고, ciprofloxain에 대해서는 4×10-10 에서 5×10-였다.
결 론 : 이 연구에서 polymyxin B와 ciprofloxacin에 대한 P. aeruginosa의 돌연변이체빈도는 비슷하였다. 따라서 이 균주에 대해 광범위한 polymycin B를 사용하는 것은 상당한 정도의 내성균주의 출현을 야기할 것이다.

다국어 초록 (Multilingual Abstract)

Backgroud : Infection caused by multi-drug resistant (MDR) Gram-negative organisms such as Pseudomonas and Acinetobacter species is one of emerging important problems in modern hospitals. To treat multi-drug resistant non-fermenting Gram-negatives, polymyxins which were used in 1960s, but abandoned because of grave toxicities such as renal toxicity are reused. The objective of this study was to estimate the probability of resistance development of the clinical isolates of Pseudomonas aeruginosa to polymyxins.
Methods and Materials : Twenty-nine multidrug-resistant P. aeruginosa isolates were collected from Dankook University Hospital and Seoul National University Hospital in 2000 and tested for antimicrobial susceptibility test, minimal inhibitory concentration (MIC), mutant prevention concentration (MPC) and mutant frequency to ciprofloxacin and polymyxin B.
Results : The MIC50 and MIC90 of polymyxin B for the isolates were 2 and 2 g/mL, and those of ciprofloxacin were 0.5 and 4 g/mL, respectively. Thirteen of 29 isolates developed polymyxin B-resistant mutants but all 29 isolates, ciprofloxacin-resistant mutants. The MPC50 and MPC90 of polymyxin B were 32 and 64 g/mL, and those values of ciprofloxacin were 4 and 64 g/mL. Mutation frequencies of polymyxin B ranged from 2×10-9 to 2×10-7, and those of ciprofloxacin from 4×10-10 to 5×10-7.
Conclusions : Mutation frequencies of polymyxin B were similar to those of ciprofloxacin, suggesting appreciable development of resistant mutants with wide usage of polymyxins.

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