First, the diagnosis of bacterial infection is indicated for the use
of antibiotics.
According to the patient’s symptoms, signs, laboratory tests and imaging results, a comprehensive judgment was made to determine whether it was bacterial infection. Symptoms such as fever, cough and sputum may be respiratory tract infections, but they may be caused by viruses, bacteria or other pathogens. Bacterial infection can be diagnosed if the inflammatory indicators such as white blood cell count, neutrophil and C-reactive protein are positive, and pathogenic bacteria are found in sputum culture or blood culture, and the use of antibiotics is reasonable at this time. If it is only a common cold, mostly caused by viruses, the use of antibiotics without bacterial infection is ineffective, but may increase the risk of adverse reactions and bacterial resistance.
2. Identify the pathogen of infection as soon as possible, and select antibiotics
according to the type of pathogen and the results of bacterial drug sensitivity test. Before
starting antimicrobial therapy, appropriate specimens should be taken for etiological examination, such as blood, sputum, urine, pus, etc. However, when the patient’s condition is critical, empirical antimicrobial therapy can be given after the specimen is sent for examination, and the medication can be adjusted after the etiological results come out. For example, for patients with severe community-acquired pneumonia, when the pathogen is not clear, antibiotics that may cover common pathogens can be selected according to the patient’s age, underlying disease, clinical signs and other factors, such as β-lactams combined with macrolides. When the sputum culture results show that Streptococcus pneumoniae is sensitive to penicillin, penicillin antibiotics can be used pertinently. If the drug sensitivity results show that the pathogenic bacteria are resistant to the antibiotics used, the effective antibiotics should be replaced in time to improve the therapeutic effect.
3. Select the drug
according to the characteristics of the antibacterial effect of the drug and the characteristics of the process in vivo
Different antibacterial drugs have different antibacterial spectrums. For example, penicillin mainly has strong antibacterial effect on Gram-positive bacteria such as Streptococcus and Staphylococcus, while aminoglycosides have good effect on Gram-negative bacilli such as Escherichia coli and Klebsiella. At the same time, the pharmacokinetic characteristics of the drug, such as absorption, distribution, metabolism and excretion, should be considered. For central nervous system infections, antibiotics that can penetrate the blood-brain barrier should be selected, such as chloramphenicol, ceftriaxone, etc. For urinary system infections, drugs that are mainly excreted by the kidney can be selected, such as nitrofurantoin, which has a higher concentration in the urine and is conducive to the removal of bacteria in the urinary tract.
4. The treatment plan of antibiotics should be formulated
according to the patient’s condition, the types of pathogens and the characteristics of antibiotics.
(I) Variety selection
Antibiotics were selected
according to the types of pathogens, drug sensitivity results, infection sites, severity of infection and physiological and pathological conditions of patients. For mild infections, oral antibiotics can be used, such as amoxicillin for mild staphylococcal infections of skin and soft tissue; for severe infections, intravenous antibiotics should be used, such as carbapenems such as imipenem for severe pneumonia. For patients with hepatic and renal insufficiency, antibiotics with greater damage to hepatic and renal function should be avoided. For example, when aminoglycosides are used in patients with renal insufficiency, the dosage should be adjusted or used with caution to avoid aggravating renal damage.
(II) Dosage
Administer
according to the therapeutic dosage range of various antibacterial drugs. For the treatment of severe infections and infections in areas where antibiotics are not easily accessible, the dosage should be larger, while for mild infections, smaller doses can be used. For example, in the treatment of infective endocarditis, the dosage of penicillin and other antibacterial drugs is often higher than conventional dosage in order to ensure that the effective antibacterial concentration is achieved in the vegetation. At the same time, adverse drug reactions should be considered to avoid toxic reactions caused by excessive dosage.
(III) Route
of administration
For mild and moderate infections, the drug can be administered orally; for patients with severe infections and systemic infections, the initial treatment should be administered intravenously to ensure efficacy. When the patient’s condition improves, oral administration can be used instead. For example, when patients with community-acquired pneumonia are in serious condition and have high fever, intravenous infusion of cefuroxime and other antibiotics should be given first, and oral cefuroxime axetil can be used to continue treatment after the body temperature is normal and the symptoms are relieved. Intravenous or other appropriate routes of administration should also be chosen for patients who cannot or cannot tolerate oral administration, such as comatose patients.
(IV) Administration times
The number of doses was determined
based on pharmacokinetic and pharmacodynamic principles. Time-dependent antimicrobial agents, such as β-lactams, should be administered multiple times a day to maintain the effective concentration of the drug in the body; concentration-dependent antimicrobial agents, such as aminoglycosides and fluoroquinolones, can be administered once a day to achieve a higher peak concentration to enhance the bactericidal effect.
(V) Course of treatment
The course of
antimicrobial therapy varies depending on the infection. Generally, it should be used until 72-96 hours after the body temperature is normal and the symptoms subside. Special cases, such as septicemia, infective endocarditis, osteomyelitis, tuberculosis, etc., require a longer course of treatment. For example, the course of treatment for acute cystitis is generally 3-7 days, while for acute pyelonephritis, the course is usually 10-14 days; for Mycobacterium tuberculosis infection, the course may be as long as 6-9 months or even longer. Early discontinuation of the drug may lead to recurrence of infection, while prolonged treatment increases the risk of adverse reactions and bacterial resistance. 5. There should be clear indications
for the combined use of antibiotics.
(1) Serious infections whose pathogenic bacteria have not yet been identified, including serious infections in immunocompromised persons, can be combined with drugs to expand the antimicrobial spectrum and cover possible pathogenic bacteria. For example, for patients with agranulocytosis and fever, antibiotics against Gram-negative bacteria and Gram-positive bacteria, such as ceftazidime and vancomycin, can be used in combination, and the medication can be adjusted after the etiological results are clear.
(2) Mixed infections of aerobic and anaerobic bacteria that cannot be controlled by a single antibiotic, such as peritonitis caused by abdominal organ perforation, are mostly mixed infections of aerobic and anaerobic bacteria in the gastrointestinal tract, which can be combined with anti-anaerobic drugs such as metronidazole and cephalosporins.
(3) Severe infections such as infective endocarditis or septicemia that cannot be effectively controlled by a single antibiotic. For infective endocarditis, especially caused by drug-resistant bacteria such as Staphylococcus aureus, β-lactams and aminoglycosides are often used in combination to enhance the bactericidal effect and improve the survival rates.
(4) For infections that require a long course of treatment but are susceptible to resistance to certain antibiotics, such as tuberculosis, the combined use of isoniazid, rifampicin, pyrazinamide, ethambutol and other anti-tuberculosis drugs can reduce the production of drug-resistant bacteria and improve the therapeutic effect.
(5) Drugs with synergistic or additive antibacterial effects should be used in combination to avoid the use of drugs with antagonistic antibacterial effects. For example, antagonistic effects may occur when bactericides (e.g., beta-lactams) and bacteriostats (e.g., macrolides) are used in combination, but in some specific situations (e.g., when treating community-acquired pneumonia), the combination may be beneficial and needs to be evaluated with caution. At the same time, the variety of drug combination should not be too much, generally two kinds are appropriate, too much combination may increase the incidence of adverse reactions.
6. Pay attention to the use
of antibiotics in special groups.
(1) The physiological function of the elderly decreases, the function of liver and kidney decreases, and the tolerance to drugs decreases. When using antibiotics, the dosage should be adjusted according to the renal function, and the drugs with great damage to liver and kidney function should be avoided. At the same time, the clinical signs of infection in the elderly may not be typical, so we should be more cautious in diagnosis and closely observe the adverse reactions in the course of treatment. (2) The physiological characteristics of children are different from those of adults, such as the imperfect development of liver and kidney functions, and the weak ability of drug metabolism and excretion. Aminoglycosides may cause hearing damage in children and should be used with caution; quinolones may affect the development of cartilage in children and should not be used in general. When choosing antibiotics, the dosage should be calculated according to children’s weight, age and other factors, and appropriate dosage forms should be selected, such as granules, syrups and other convenient dosage forms for children.
(3) Pregnant and lactating women should consider the effects of antibiotics on the fetus when using antibiotics during pregnancy. For example, tetracyclines can affect the development of fetal teeth and bones and should not be used during pregnancy; aminoglycosides may damage fetal hearing and should also be avoided. When lactating women use antibiotics, they should pay attention to whether the drugs will affect the baby through milk secretion, such as chloramphenicol can be secreted through milk, which may cause adverse reactions to the baby, and should be used with caution or suspended lactation. In a word, the use of antibiotics should strictly follow the above principles to improve the therapeutic effect, reduce the occurrence of adverse reactions and bacterial resistance, and ensure the safety and health of patients.
