不同部位感染的抗菌（Antibacterial activity of different parts of infection）1 antibiotics selection during respiratory infectionThe 1.1 upper respiratory tract infection of upper respiratory tract infection is a general term, including the common cold, acute sinusitis, pharyngitis, laryngitis, pharyngitis tonsils. The pathogens for more than 90% of a common virus, rhinovirus, adenovirus, influenza virus, parainfluenza virus. Bacteria account for only about 10%. Most of these patients are not high in blood and short in duration (usually 1 weeks). Treatment to rest, drinking water and symptomatic based, without the use of antibiotics. Antibiotics can be used if symptoms persist for 710 days without improvement, with fever, elevated white blood cells, or purulent or non purulent complications (rheumatism or glomerulonephritis). Antibiotics are the first choice of penicillins (penicillin, G, amoxicillin), and one or two generation cephalosporins and macrolides are also available. The course of general antibiotics is 57 days, accompanied by rheumatism and glomerulonephritis for 1014 days. If severe purulent complications occur, the course of antibiotics may be prolonged. 1.2 lower respiratory tract infections are the most common infectious disease. Including acute and chronic bronchitis, pulmonary infection and so on. The pathogens (bacteria are common gram positive cocci, such as Streptococcus pneumoniae, Staphylococcus aureus; gram negative bacteria, such as Klebsiella pneumoniae, Haemophilus influenzae, Pseudomonas aeruginosa, Escherichia coli, proteus; anaerobic bacteria such as Corynebacterium, Fusobacterium, etc.), viruses, fungi, protozoa mycoplasma, chlamydia, etc. The bacterial infection rate was 80% in adults and 70% in children. The proportion of fungal infections increased significantly in immunosuppressed, aged, large doses of antibiotics and antibiotics. At present, the medical community is generally accepted that lower respiratory tract infections are mainly gram positive cocci (mainly pneumococcus), followed by Gram negative bacilli (the most common is Klebsiella pneumoniae). Approximately 60% of hospital acquired infections were gram negative bacilli, most of which were Pseudomonas aeruginosa. In the past, the treatment of lower respiratory tract infection with penicillin was the first choice, but in recent years, the resistance of bacteria has changed greatly. For example, the resistance rate of pneumococcus to oxacillin and ampicillin was 50%, and the rate of resistance to erythromycin and clindamycin was 50% to 70%. The resistance rate of Staphylococcus aureus and Staphylococcus epidermidis to penicillin was over 97%, the resistance rate of erythromycin and clindamycin was about 70%, and vancomycin resistant grape bacteria were also reported abroad. But the resistance rate of sulfamethoxazole and quinolones is low, especially for the new generation quinolones. Therefore, the combination of sulfamethoxazole and quinolones can often achieve ideal curative effect. Ampicillin, amoxicillin or two generation cephalosporin is the first choice for the treatment of lower respiratory tract infection. Metronidazole or clindamycin can be added to anaerobes when combined with infection. According to the relationship between serum concentration and effect, the antibacterial effect increased with the increase of serum concentration, and the total effective time was increased by fractional administration. Beta lactam antibiotics are advocated for fractional administration. For mild to moderate infections, oral administration is possible. For patients with severe lower respiratory tract infection or other diseases, intravenous administration and combined use of antibiotics are recommended. Generally, two combinations can achieve satisfactory results.The role and mechanism of several antibiotics commonly used in respiratory system are briefly described:1.2.1 quinolones are important drugs in the treatment of lower respiratory tract infections in recent years. It has the characteristics of high tissue concentration and minimum inhibitory concentration. The drug was 2 times more concentrated in the bronchial mucosa than in the blood, 23 times higher in the alveolar epithelium than in the blood, and 915 times higher in alveolar macrophages than in the blood.1.2.2 beta lactam antibiotics are most widely used in the treatment of respiratory tract infections. They mainly include penicillins, cephalosporins and atypical beta lactam antibiotics. Beta lactam antibiotics, combined with beta lactamase inhibitors (clavulanic acid and Shubatan), significantly increased antimicrobial activity and reduced the production of resistant strains. Imipenem, Timentin, maxipime on Gram positive cocci, gram negative bacteria, anaerobic bacteria have potent bactericidal activity.1.2.3 is a macrolide antibiotic most commonly used in treatment of bacterial respiratory tract infection of gram positive cocci (Streptoc