ISPN Review Characteristics of Antimicrobial Drugs抗微生物药的特点 Terms and Concepts术语与概念
Several terms are used to describe these drugs. Anti-infective and antimicrobial include antibacterial, antiviral, and antifungal drugs; antibacterial and antibiotic refer to drugs used in bacterial infections and are often used interchangeably. Additional terms for antibacterial drugs include broad spectrum, for those effective against several groups of microorganisms, and narrow spectrum, for those effective against a few groups. The action of an antibacterial drug is usually described as bactericidal (kills the microorganism) or bacteriostatic (inhibits growth of the microorganism). Whether a drug is bactericidal or bacteriostatic often depends on its concentration at the infection site and the susceptibility of the microorganism to the drug.
Mechanisms of Action 作用机制
Most antimicrobial drugs act on a specific target in the infecting organism. Almost any structure unique to infecting organism, such as proteins or nucleic acids, can be a target for antibiotics. Specific mechanisms of action of antimicrobial drugs include the following:
■ Inhibition of bacterial cell wall synthesis or activation of enzymes that disrupt bacterial cell walls (e.g., penicillins, cephalosporins, vancomycin)
抑制细菌细胞壁合成或激活瓦解细菌细胞壁的酶(如,青霉素、先锋霉素、万古霉素)
■ Inhibition of protein synthesis by bacteria or production of abnormal bacterial proteins (e.g., aminoglycosides, clindamycin, macrolides, ketolides, tetracyclines). These drugs bind irreversibly to bacterial ribosomes, intracellular structures that synthesize proteins. When antimicrobial drugs are bound to the ribosomes, bacteria cannot synthesize the proteins necessary for cell walls and other structures.
■ Disruption of microbial cell membranes (e.g., antifungals)
瓦解微生物细腻膜(如抗真菌药)
■ Inhibition of organism reproduction by interfering with nucleic acid synthesis (e.g., fluoroquinolones, rifampin, anti–acquired immunodeficiency syndrome antivirals)
通过干扰核酸合成抑制生物繁殖(如,氟喹诺酮类,利福平,抗爱滋病病毒药)
■ Inhibition of cell metabolism and growth (e.g., sulfonamides, trimethoprim)
抑制细胞代谢和生长(如磺胺类药、甲氧苄啶)
Indications for Use 适应症
Antimicrobial drugs are used to treat and prevent infections. Because laboratory tests (except Gram’s stain and a rapid test for group A streptococci) to identify causative organisms usually take 24 hours or longer, empiric therapy against the most likely pathogens is often begun. After organisms are identified, more specific therapy is instituted. Prophylactic therapy is recommended to prevent the following:
■ Group A streptococcal infections and possibly rheumatic fever, rheumatic heart disease, and glomerulonephritis. Penicillin is commonly used.
A型链球菌感染和可能的风湿热、风湿性以及病及肾小球肾炎。建议使用青霉素。
■ Bacterial endocarditis in patients with cardiac valvular disease who are having dental, surgical, or other invasive procedures. Amoxicillin or ampicillin, with an aminoglycoside, is usually recommended for at-risk persons undergoing certain types of procedures.
■ Tuberculosis in patients with latent tuberculosis infection.
潜伏结核感染患者的结构病。
■ Perioperative infections in high-risk patients (e.g., those whose resistance to infection is lowered because of age, poor nutrition, disease, or drugs) and for high-risk surgical procedures (e.g., cardiac or GI surgery, certain orthopedic procedures, organ transplants)
■ Sexually transmitted diseases (e.g., gonorrhea, syphilis, chlamydial infections) after exposure has occurred
暴露无遗后出现的性传病(发淋病、梅毒、衣原体感染)
■ Recurrent urinary tract infections in premenopausal, sexually active women. A single dose of a fluoroquinolone or trimethoprim-sulfamethoxazole for two doses, taken after sexual intercourse, is often effective.
Vocabulary for Today
antimicrobial – a. n. 抗菌的,抗菌药
broad spectrum – 广谱
narrow spectrum – 窄谱
bactericidal – a. n. 杀菌的
bacteriostatic – a. n. 细菌抑制的,抑菌药
cephalosporin – n. 头孢菌素
vancomycin – n. 万古霉素
clindamycin – n. 克林霉素
macrolides – n. 大环内酯类
ketolides – n. 酮内酯
tetracycline – n. 四环素
ribosome – n. 核糖体
rifampin – n. 利福平
amoxicillin – n. 阿莫西林
ampicillin – n. 氨卞西林
Test 1. When an anti-infective agent is said to be no longer effective for a patient, the patient has developed:
A. Immunity
B. Tolerance
C. Non-responsiveness
D. Resistance 2. A middle-aged woman came to the ER and complains of ringing in the ears, paresthesias of the extremities, and erythema of the back. She also noticed that she had decreased urine output. What history of drug intake should the nurse ask?
A. Oral contraceptive pills (OCPs)
B. Antifungals
C. Vancomycin
D. Trimethoprim-sulfamethoxazole
本期ISPN Review答案: 1. D. Resistance. It occurs when the cells of the invading pathogens no longer respond to the drug. 2. C. Vancomycin. Its toxicity includes ototoxicity, renal failure, and red man syndrome characterized by erythema on the neck and back, paresthesia, chills, severe hypotension, and fever.