Hakanen A, Kotilainen P, Jalava J, Siitonen A, Huovinen P
Antimicrobial Research Laboratory, National Public Health Institute, Turku University, Turku, Finland.
J Clin Microbiol. 1999 Nov;37(11):3572-7. doi: 10.1128/JCM.37.11.3572-3577.1999.
We evaluated 1,010 Salmonella isolates classified as fluoroquinolone susceptible according to the National Committee for Clinical Laboratory Standards guidelines for susceptibility to nalidixic acid and three fluoroquinolones. These isolates were divided into two distinct subpopulations, with the great majority (n = 960) being fully ciprofloxacin susceptible and a minority (n = 50) exhibiting reduced ciprofloxacin susceptibility (MICs ranging between 0.125 and 0.5 microg/ml). The less ciprofloxacin-susceptible isolates were uniformly resistant to nalidixic acid, while only 12 (1.3%) of the fully susceptible isolates were nalidixic acid resistant. A similar association was observed between resistance to nalidixic acid and decreased susceptibility to ofloxacin or norfloxacin. A mutation of the gyrA gene could be demonstrated in all isolates for which the ciprofloxacin MICs were >/= 0.125 microg/ml and in 94% of the nalidixic acid-resistant isolates but in none of the nalidixic acid-susceptible isolates analyzed. Identification of nalidixic acid resistance by the disk diffusion method provided a sensitivity of 100% and a specificity of 87.3% as tools to screen for isolates for which the MICs of ciprofloxacin were >/= 0.125 microg/ml. We regard it as important that microbiology laboratories endeavor to recognize these less susceptible Salmonella strains, in order to reveal their clinical importance and to survey their epidemic spread.
我们根据美国国家临床实验室标准委员会关于萘啶酸和三种氟喹诺酮类药物敏感性的指南，对1010株被分类为对氟喹诺酮敏感的沙门氏菌分离株进行了评估。这些分离株被分为两个不同的亚群，绝大多数（n = 960）对环丙沙星完全敏感，少数（n = 50）对环丙沙星的敏感性降低（MIC范围在0.125至0.5微克/毫升之间）。对环丙沙星敏感性较低的分离株对萘啶酸均耐药，而完全敏感的分离株中只有12株（1.3%）对萘啶酸耐药。在对萘啶酸耐药和对氧氟沙星或诺氟沙星敏感性降低之间也观察到了类似的关联。在所有环丙沙星MIC≥0.125微克/毫升的分离株以及94%对萘啶酸耐药的分离株中都能检测到gyrA基因突变，但在所分析的对萘啶酸敏感的分离株中均未检测到。通过纸片扩散法鉴定萘啶酸耐药性，作为筛选环丙沙星MIC≥0.125微克/毫升分离株的工具，其敏感性为100%，特异性为87.3%。我们认为微生物实验室努力识别这些敏感性较低的沙门氏菌菌株很重要，以便揭示它们的临床重要性并调查其流行传播情况。
