The fluoroquinolones are a relatively new synthetic class of antibiotics with a broad spectrum of activity. Fluoroquinolones include ciprofloxacin (Cipro), which is the most widely used fluoroquinolone; gemifloxacin (Factive), levofloxacin (Levaquin), lomefloxacin (Maxaquin), moxifloxacin (Avelox), norfloxacin (Noroxin), and ofloxacin (Floxin, Ocuflox).
The fluoroquinolones enter the bacterial cell by passive diffusion through channels in the cell membrane. Once inside, they interfere with the action of DNA enzymes necessary for the growth and reproduction of the bacteria. This leads to cell death because the bacterial DNA is damaged and the cell cannot be maintained. The fluoroquinolones have the advantage of a unique way of disrupting bacterial activity. There is little cross-resistance with other forms of antibiotics. However, misuse of these drugs in the short time the class has been available has led to the existence of resistant strains of bacteria.
The fluoroquinolones are indicated for treating infections caused by susceptible strains of gram-negative bacteria, including E. coli, P. mirabilis, K. pneumoniae, Enterobacter cloacae, Proteus vulgaris, Proteus rettgeri, Morganella morganii, Moraxella catarrhalis, H. influenzae, H. parainfluenzae, P. aeruginosa, Citrobacter freundii, S. aureus, Staphylococcus epidermidis, some Neisseria gonorrhoeae, and group D streptococci. These infections frequently include urinary tract, respiratory tract, and skin infections. Ciprofloxacin is effective against a wide spectrum of gram-negative bacteria.
In 2001, it was approved for prevention of anthrax infection in areas that might be exposed to germ warfare. It is also effective against typhoid fever.
2001年，该药获准用于可能接触细菌战地区的炭疽感染预防。它还对伤寒症有效。
Pharmacokinetics药动学
The fluoroquinolones are absorbed from the GI tract, metabolized in the liver, and excreted in the urine and feces. These drugs are widely distributed in the body and cross the placenta and enter breast milk.
氟喹诺酮经胃肠道吸收、肝代谢、尿粪排出。药物广泛分布于身体，穿过屏障，进入乳汁。
Ciprofloxacin is available in injectable, oral, and topical forms. Gemifloxacin, lomefloxacin, and moxifloxacin are oral agents. Levofloxacin is available in oral and IV forms.
Because of its parenteral availability, it may be preferred for severe infections or for use when the patient cannot take oral drugs. Norfloxacin is only available in an oral form. Ofloxacin can be given IV or orally and is also available as an ophthalmic agent for the treatment of ocular infections caused by susceptible bacteria.
fluoroquinolones – n. 氟喹诺酮类药
ciprofloxacin – n. 环丙沙星 Cipro – n. 盐酸环丙沙星制剂
gemifloxacin – n. 吉米沙星 Factive – n. 吉速星
levofloxacin – n. 左氧氟沙星 Levaquin – n. 【奥】利氟肯
lomefloxacin – n. 洛美沙星 Maxaquin – n. 美西肯
moxifloxacin – n. 莫西沙星 Avelox – n. 拜复乐
norfloxacin – n. 诺氟沙星 Noroxin – n. 诺氟沙星片
ofloxacin – n. 氧氟沙星 Floxin – n. 【奥】氟洛星 Ocuflox – n. 氧氟沙星眼液 E. coli -- n. 大肠杆菌 P. mirabilis – n.奇异变形杆菌 K. pneumoniae – n. 肺炎克雷白菌 Enterobacter cloacae – n. 阴沟肠杆菌 Proteus vulgaris – n. 普通变形杆菌 Proteus rettgeri – n. 雷氏变形菌 Morganella morganii – n. 摩氏摩根菌 Moraxella catarrhalis – n. 粘膜炎莫拉菌 H. parainfluenzae – n. 副流感嗜血杆菌 P. aeruginosa – n. 铜绿假单胞菌 Citrobacter freundii – n. 弗氏柠檬细菌 S. aureus – n. 金黄色葡萄球菌 Staphylococcus epidermidis – n. 表皮葡萄球菌 Neisseria gonorrhoeae – n. 淋球菌淋病奈瑟球菌
Test 1. What is the minimum bactericidal concentration (MBC)?
A. The lowest concentration of an antibiotic needed to suppress bacterial growth completely
B. The lowest concentration of an antibiotic needed to reduce the number of bacterial colonies by 99.9%
C. The lowest concentration of an antibiotic needed to produce effects
D. The lowest dose of an antibiotic needed to eradicate bacteria
2. Which test is the most widely used method for assessing drug sensitivity?
A. Minimum inhibitory concentration (MIC)
B. Minimum bacterial concentration (MBC)
C. Broth dilution
D. Disk diffusion
本期ISPN Review答案： 1. B. The lowest concentration of an antibiotic needed to reduce the number of bacterial colonies by 99.9%
The MBC is the lowest concentration of drug that produces a 99.9% decline in the number of bacterial colonies (indicating bacterial kill). The lowest antibiotic concentration needed to suppress bacterial growth or to produce effects and the lowest antibiotic dose needed to eradicate bacteria are incorrect descriptions of MBC.
2. D. Disk diffusion
The most widely used method for assessing drug sensitivity is the disk diffusion test, also known as the Kirby-Bauer test. Through diffusion, an antibiotic-containing zone becomes established around each disk. As the bacteria proliferate, growth is inhibited around the disks that contain an antibiotic to which the bacteria are sensitive.
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