Dartmouth-Hitchcock Medical Center, Lebanon.
Geisel School of Medicine at Dartmouth, Hanover, New Hampshire.
Otol Neurotol. 2021 Aug 1;42(7):e887-e893. doi: 10.1097/MAO.0000000000003113.
Ciprofloxacin-resistant pathogens are inhibited by high concentrations of ciprofloxacin found in commercially-available ototopical solutions.
Ciprofloxacin-resistant pathogens in otitis media are currently treated with ototopical ciprofloxacin suspensions. This is done irrespective of laboratory-reported ciprofloxacin susceptibility, under the assumption that the high concentration of ciprofloxacin applied topically is sufficient to overcome antimicrobial resistance.
We evaluated 34 ciprofloxacin-resistant isolates consisting of Staphylococcus aureus, Pseudomonas aeruginosa, Corynebacterium spp., and Turicella otitidis. Ciprofloxacin minimum inhibitory concentration (MIC) assays and clinical ototopical solution minimum bactericidal concentration (CMBC) assays were performed.
Amongst the ciprofloxacin-resistant isolates, ciprofloxacin MICs ranged from 8 to 256 mcg/ml (mean: 87.1 mcg/ml) and CMBCs ranged from 23.4 to 1500 mcg/ml (mean: 237.0 mcg/ml). There were no significant differences with respect to MIC in comparing P. aeruginosa versus Corynebacterium spp. (mean: 53.3 versus 55.2, p = 0.86), S. aureus versus P. aeruginosa (mean: 128.0 versus 53.3, p = 0.34), and S. aureus versus Corynebacterium spp. (mean: 128.0 versus 55.2, p = 0.09). The correlation between ciprofloxacin MIC and CMBC was poor (Pearson's r = -0.08, p = 0.75).
Ciprofloxacin-resistant pathogens commonly recovered from otitis media exhibit highly variable ciprofloxacin MIC and CMBC levels. Ciprofloxacin was able to inhibit growth in all isolates tested at MIC levels less than or equal to 256 mcg/ml; however, CMBC's up to 1500 mcg/ml were observed within that same group. The clinical relevance of these in vitro MICs is unclear due in part to higher bactericidal concentrations (CMBC) in several strains. Our results suggest that treatment failures may be due to a combination of factors rather than high-level resistance alone.
市售的滴耳液中的高浓度环丙沙星可抑制对环丙沙星耐药的病原体。
目前，耐环丙沙星的中耳炎病原体采用滴耳液中的环丙沙星混悬液治疗。这是在不考虑实验室报告的环丙沙星药敏性的情况下进行的，因为人们认为局部应用的高浓度环丙沙星足以克服抗菌耐药性。
我们评估了 34 株耐环丙沙星的分离株，包括金黄色葡萄球菌、铜绿假单胞菌、棒状杆菌属和耳炎螺旋体。进行了环丙沙星最小抑菌浓度（MIC）检测和临床滴耳液最小杀菌浓度（CMBC）检测。
在耐环丙沙星的分离株中，环丙沙星 MIC 范围为 8 至 256 mcg/ml（平均值：87.1 mcg/ml），CMBC 范围为 23.4 至 1500 mcg/ml（平均值：237.0 mcg/ml）。铜绿假单胞菌与棒状杆菌属（平均值：53.3 与 55.2，p=0.86）、金黄色葡萄球菌与铜绿假单胞菌（平均值：128.0 与 53.3，p=0.34）和金黄色葡萄球菌与棒状杆菌属（平均值：128.0 与 55.2，p=0.09）之间的 MIC 无显著差异。环丙沙星 MIC 与 CMBC 之间的相关性较差（Pearson r=-0.08，p=0.75）。
从中耳炎中常分离到的耐环丙沙星病原体表现出高度可变的环丙沙星 MIC 和 CMBC 水平。在 MIC 水平低于或等于 256 mcg/ml 的情况下，所有测试的分离株均能抑制生长；然而，在同一组中观察到 CMBC 高达 1500 mcg/ml。由于某些菌株的杀菌浓度（CMBC）较高，这些体外 MIC 的临床相关性尚不清楚。我们的结果表明，治疗失败可能是多种因素的组合所致，而不仅仅是高水平耐药性。
