Aldous W K, Jensen R, Sieck B M
Department of Clinical Investigation, Madigan Army Medical Center, Tacoma, Washington 98431, USA.
Ear Nose Throat J. 1998 Jul;77(7):554-7.
Topical anesthetics are commonly used in the evaluation of nasal pathology. The anesthetics routinely used, 4% lidocaine with phenylephrine, or 4% cocaine, have been demonstrated to have varying inhibitory effects on bacterial cultures. The present study examined the antimicrobial activity of these topical anesthetics used in nasal procedures. The pathogens used were Branhamella catarrhalis, Enterobacter sp., Haemophilus influenzae, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus and Streptococcus pneumoniae. Organisms were against two-fold serial dilutions of stock preparations of 4% lidocaine with 0.25% phenylephrine, 0.25% phenylephrine, 0.1% methylparaben, 250 mg/ml ampicillin, and 4% cocaine. The minimum inhibitory concentration and minimum bactericidal concentration for each of the solutions were obtained. The bacteria studied varied gently in their susceptibility to lidocaine with phenylephrine versus cocaine: Cocaine consistently exhibited greater antimicrobial activity than lidocaine. Phenylephrine and methylparaben showed slight antimicrobial activity. These topical anesthetics have slight bactericidal activity against nasal pathogens, which can sometimes lead to false-negative results. Otolaryngologists should recognize the possible antimicrobial effects of topical anesthetics when culturing specimens. This is especially important when the specimen will be used for guidance of antimicrobial therapy, as in the case of the critically ill patient who requires aspiration for organism-specific therapy. Further studies, specifically in vivo experiments, are needed to determine if use of the drugs produces a significant change in the ability to culture organisms from these sites. This type of study would, however, be difficult to perform, since most patients requiring aspiration are already on high-dose antibiotics that would inhibit the growth of most microorganisms. A modified aspiration technique using a less concentrated topical anesthetic will likely be required to increase the chances of obtaining positive cultures.
局部麻醉剂常用于鼻腔疾病的评估。常用的麻醉剂，4%利多卡因加去氧肾上腺素，或4%可卡因，已被证明对细菌培养有不同的抑制作用。本研究检测了这些用于鼻腔手术的局部麻醉剂的抗菌活性。所用病原体为卡他莫拉菌、肠杆菌属、流感嗜血杆菌、肺炎克雷伯菌、铜绿假单胞菌、金黄色葡萄球菌和肺炎链球菌。将这些微生物分别置于4%利多卡因加0.25%去氧肾上腺素、0.25%去氧肾上腺素、0.1%对羟基苯甲酸甲酯、250mg/ml氨苄西林和4%可卡因储备液的两倍系列稀释液中。获得了每种溶液的最低抑菌浓度和最低杀菌浓度。所研究的细菌对利多卡因加去氧肾上腺素和可卡因的敏感性略有不同：可卡因始终表现出比利多卡因更强的抗菌活性。去氧肾上腺素和对羟基苯甲酸甲酯显示出轻微的抗菌活性。这些局部麻醉剂对鼻腔病原体有轻微的杀菌活性，这有时会导致假阴性结果。耳鼻喉科医生在培养标本时应认识到局部麻醉剂可能的抗菌作用。当标本将用于指导抗菌治疗时，这一点尤为重要，例如对于需要抽吸进行针对特定病原体治疗的重症患者。需要进一步的研究，特别是体内实验，以确定使用这些药物是否会显著改变从这些部位培养微生物的能力。然而，这类研究很难进行，因为大多数需要抽吸的患者已经在使用高剂量抗生素，这会抑制大多数微生物的生长。可能需要采用一种使用浓度较低的局部麻醉剂的改良抽吸技术，以增加获得阳性培养结果的机会。
