Ritchie D J, Hopefl A W, Milligan T W, Byrne J E, Maddux M S
St. Louis College of Pharmacy, Missouri.
Clin Ther. 1993 Jan-Feb;15(1):107-13.
Macrolide and beta-lactam antimicrobial agents are frequently used for the treatment of upper and lower respiratory tract infections and skin or skin structure infections. To evaluate the relative in vitro activity of these antimicrobial drugs against organisms commonly involved in these infections, we tested clarithromycin, erythromycin, cefprozil, cefuroxime, cefaclor, cephalexin, amoxicillin, amoxicillin/clavulanate, and doxycycline against 174 gram-positive and gram-negative clinical isolates, including Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, group A beta-hemolytic streptococci, alpha-hemolytic streptococci, Escherichia coli, and Klebsiella pneumoniae. Manual broth microdilution susceptibility testing was used with a standard inoculum of 5 x 10(4) colony-forming units/well at pH of 7.2. Clarithromycin was the most active agent against streptococci. Methicillin-susceptible S aureus exhibited resistance to both clarithromycin and erythromycin, but was susceptible to cefprozil, cefuroxime, amoxicillin/clavulanate, and doxycycline. Cefprozil was at least as active as cefuroxime, cefaclor, and cephalexin against all organisms tested, but was fourfold less active than doxycycline against E coli and 16-fold less active than clarithromycin versus S pneumoniae. The gram-negative isolates tested showed resistance to clarithromycin and erythromycin; however, cefprozil was as active as amoxicillin/clavulanate against K pneumoniae and E coli. These results demonstrate that clarithromycin provides superior in vitro activity against common streptococci, while cefprozil, cefuroxime, amoxicillin/clavulanate, and doxycycline provide greater activity against methicillin-susceptible S aureus, K pneumoniae, and E coli. Prospective clinical trials are needed to determine the clinical significance of these findings.
大环内酯类和β-内酰胺类抗菌药物常用于治疗上、下呼吸道感染以及皮肤或皮肤结构感染。为评估这些抗菌药物对这些感染中常见病原体的相对体外活性，我们测试了克拉霉素、红霉素、头孢丙烯、头孢呋辛、头孢克洛、头孢氨苄、阿莫西林、阿莫西林/克拉维酸和多西环素对174株革兰氏阳性和革兰氏阴性临床分离株的活性，这些分离株包括金黄色葡萄球菌、表皮葡萄球菌、肺炎链球菌、A组β溶血性链球菌、α溶血性链球菌、大肠杆菌和肺炎克雷伯菌。采用手工肉汤微量稀释法进行药敏试验，接种标准菌量为5×10⁴菌落形成单位/孔，pH值为7.2。克拉霉素对链球菌的活性最强。甲氧西林敏感的金黄色葡萄球菌对克拉霉素和红霉素均耐药，但对头孢丙烯、头孢呋辛、阿莫西林/克拉维酸和多西环素敏感。头孢丙烯对所有测试菌株的活性至少与头孢呋辛、头孢克洛和头孢氨苄相当，但对大肠杆菌的活性比对多西环素低四倍，对肺炎链球菌的活性比对克拉霉素低16倍。测试的革兰氏阴性分离株对克拉霉素和红霉素耐药；然而，头孢丙烯对肺炎克雷伯菌和大肠杆菌的活性与阿莫西林/克拉维酸相当。这些结果表明，克拉霉素对常见链球菌具有卓越的体外活性，而头孢丙烯、头孢呋辛、阿莫西林/克拉维酸和多西环素对甲氧西林敏感的金黄色葡萄球菌、肺炎克雷伯菌和大肠杆菌具有更强的活性。需要进行前瞻性临床试验以确定这些发现的临床意义。
