The tetracyclines were developed as semisynthetic antibiotics based on the structure of a common soil mold. They are composed of four rings, which is how they got their name. Researchers have developed newer tetracyclines to increase absorption and tissue penetration. Widespread resistance to the tetracyclines has limited their use in recent years.
The tetracyclines work by inhibiting protein synthesis in a wide range of bacteria, leading to the inability of the bacteria to multiply. Because the affected protein is similar to a protein found in human cells, these drugs can be toxic to humans at high concentrations.
Tetracyclines are indicated for treatment of infections caused by Rickettsiae, M. pneumoniae, Borrelia recurrentis, H. influenzae, Haemophilus ducreyi, Pasteurella pestis, Pasteurella tularensis, Bartonella bacilliformis, Bacteroides species, Vibrio comma, Vibrio fetus, Brucella species, E. coli, E. aerogenes, Shigella species, Acinetobacter calcoaceticus, Klebsiella species, Diplococcus pneumoniae, and S. aureus; against agents that cause psittacosis, ornithosis, lymphogran-uloma venereum, and granuloma inguinale; when penicillin is contraindicated in susceptible infections; and for treatment of acne and uncomplicated GU infections caused by C. trachomatis. Some of the tetracyclines are also used as adjuncts in the treatment of certain protozoal infections.
The major adverse effects of tetracycline therapy involve direct irritation of the GI tract and include nausea, vomiting, diarrhea, abdominal pain, glossitis, and dysphagia. Fatal hepatotoxicity related to the drug’s irritating effect on the liver has also been reported. Skeletal effects involve damage to the teeth and bones. Because tetracyclines have an affinity for teeth and bones, they accumulate there, weakening the structure and causing staining and pitting of teeth and bones. Dermatological effects include photosensitivity and rash. Superinfections, including yeast infections, occur when bacteria of the normal flora are destroyed. Local effects, such as pain and stinging with topical or ocular application, are fairly common. Hematological effects are less frequent, such as hemolytic anemia and bone marrow depression secondary to the effects on bone marrow cells that turn over rapidly. Hypersensitivity reactions reportedly range from urticaria to anaphylaxis and also include intracranial hypertension.
tetracycline – n. 四环素类抗生素
semisynthetic – a. 半合成的 Sumycin – n. 【奥】苏霉素 Panmycin – n. 盘霉素
demeclocycline – n. 去甲金霉素 Declomycin – n. 地美环素
doxycycline – n. 多西环素 Doryx – n. 福多力 Periostat – n. 多西环素水合物
minocycline – n. 米诺霉素 Minocin – n. 美满霉素 Rickettsiae – n. 立克次体族 M. pneumoniae – n. 肺炎支原体 Borrelia recurrentis – n. 回归热(疏)螺旋体 Haemophilus ducreyi – n. 杜克雷嗜血杆菌 Bartonella bacilliformis – n. 杆菌状巴尔通体 Bacteroides species – n. 类杆菌属,拟杆菌属 Vibrio comma – n. 逗号弧菌 Brucella species – n. 布鲁氏杆菌属 Shigella species – n. 志贺氏菌属 Acinetobacter calcoaceticus -- n. 乙酸钙不动杆菌 Klebsiella species – n. 克雷伯氏菌属 Diplococcus pneumoniae – n. 肺炎双球菌
psittacosis – n. 鹦鹉热
ornithosis – n. 鸟疫
lymphogran-uloma venereum –性病淋巴肉芽肿
granuloma inguinale --腹股沟肉芽肿 C. trachomatis – 沙眼衣原体
1. Which instruction should a nurse include in the discharge teaching for a patient who is to start taking tetracycline (Sumycin)?
A. "You may stop taking the pills when you begin to feel better."
B. "Use sunscreen and protective clothing when outdoors."
C. "You'll have to come back to the clinic for weekly blood work."
D. "Take the medication with yogurt or milk so you won't have nausea."
2. A nurse assessing a patient who is 12 years old should associate which complication with the patient's receiving tetracycline (Sumycin) as a younger child?
A. Delay in long bone growth
B. Early onset of puberty
C. Severe face and body acne
D. Discoloration of the teeth
本期ISPN Review答案： 1. B. "Use sunscreen and protective clothing when outdoors."
Tetracyclines are bacteriostatic antibiotics; photosensitivity and severe sunburn are common adverse effects. A full course of antibiotics must always be taken. Blood studies are not necessary for therapeutic levels. Absorption decreases after ingestion of chelates, such as calcium and magnesium, so doses should be given 2 hours before or 2 hours after ingestion of milk products.
2. D. Discoloration of the teeth
Tetracycline is contraindicated in children younger than 8 years of age, because it binds to calcium in developing teeth, resulting in permanent discoloration of the teeth. Delay in long bone growth, early onset of puberty, and severe face and body acne are not adverse effects associated with tetracyclines.
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