Original Video
Clinical Beginner Series: Rational Use of Antibiotics_哔哩哔哩_bilibili
Do You Need to Use Antibiotics
- Surgery: Preoperative prevention/treatment of infection,
- For Class I surgeries, antibiotics should not be used preventively before surgery, such as elective hernia repair, varicocele, small breast mass removal, lipoma, etc. Even if used, medication should be stopped within 24 hours, with a maximum duration not exceeding 48 hours.
- Class II surgeries routinely use preventive antibiotics, including gastrointestinal, biliary tract, urinary tract, cranial, thoracic surgeries, etc. Generally, second- or third-generation cephalosporins are preferred. If there is an existing infection, use the antibiotics planned for preoperative prophylaxis; if infection indicators are normal, stop promptly. Judging this is the most difficult—using antibiotics continuously until discharge is the safest but least reasonable approach.
- Class III surgeries with confirmed infection can upgrade antibiotics postoperatively when necessary.
- The most important treatment for infection in surgery is “drainage”: no drainage means pain and infection, including sputum, urine, postoperative abdominal cavity effusion, subcutaneous wound effusion, etc.
- Internal Medicine: The situation is more complex, unlike surgery where the source of infection is more obvious; often the situation is unclear.
- Before empirical medication, consider whether there is a bacterial infection to justify antibiotic use; fever does not always mean infection. Rheumatic autoimmune diseases (systemic lupus erythematosus, rheumatoid arthritis, gout), hematological diseases (lymphoma), etc., can all cause fever.
- The most important part of infection treatment in internal medicine is “find the cause”: locate the infection source, identify the pathogen, e.g., what bacteria caused pneumonia, antibiotic sensitivity results; for fever of unknown origin: tick? typhoid? tuberculosis? hemorrhagic fever? dengue?
- Not all infections require the “big three”: vancomycin + linezolid + imipenem. The strongest is not always the most appropriate.
Which Antibiotics to Choose
Common drug-resistant bacteria:
- Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Acinetobacter baumannii, Pseudomonas aeruginosa
- Specifically: methicillin-resistant Staphylococcus aureus (MRSA), extended-spectrum beta-lactamase producing Enterobacteriaceae (ESBLs), vancomycin-resistant Enterococci (VRE), carbapenem-resistant Enterobacteriaceae (CRE), multidrug-resistant Pseudomonas aeruginosa (MDR-PA), multidrug-resistant Acinetobacter baumannii (MDR-AB)
Empirical treatment approach:
① At least judge whether the infecting bacteria are Gram-positive or Gram-negative
② Metabolism of antibiotics: {via liver (blood), biliary tract, urinary tract}, meaning where the antibiotic achieves the highest concentration
③ Sensitivity of antibiotics to particular bacteria types
④ Distribution of local drug-resistant bacteria; hospital infection control should have relevant data
G+ cocci: hemolytic streptococci, viridans streptococci, pneumococcus, Staphylococcus aureus;
G+ bacilli: Clostridium tetani, Bacillus anthracis, Corynebacterium diphtheriae, Clostridium perfringens, Lactobacillus;
G- cocci: Neisseria meningitidis, Neisseria gonorrhoeae, Moraxella catarrhalis;
G- bacilli: Escherichia coli, Proteus, Shigella, Salmonella, Pseudomonas aeruginosa, Haemophilus influenzae, Klebsiella pneumoniae, Acinetobacter baumannii.
Antibiotic Classification
[[Antibiotics]]
- β-lactam antibiotics: penicillins, cephalosporins (broad-spectrum, different types have different effects)
- Macrolides: roxithromycin, azithromycin (Mycoplasma, Chlamydia)
- Lincosamides: clindamycin, lincomycin (anaerobes and Staphylococcus aureus causing osteomyelitis)
- Polypeptides: vancomycin, desmethylvancomycin, teicoplanin (G+ bacteria)
- Aminoglycosides: streptomycin, gentamicin, amikacin (G- bacilli)
- Tetracyclines: doxycycline, tetracycline, minocycline (broad-spectrum, for special infections)
- Quinolones: norfloxacin, ofloxacin, levofloxacin, moxifloxacin (broad-spectrum)
- Chloramphenicol: chloramphenicol (rickettsia, second-line for typhoid)
- Sulfonamides; sulfamethoxazole (Bactrim), recurrent Bactrim: Bactrim + methenamine; sulfasalazine (SASP)
- Carbapenems: meropenem, ertapenem, imipenem, etc. (broad-spectrum)
- Nitroimidazoles: metronidazole, tinidazole (anaerobes)
- Antifungals: amphotericin B
How to Use
Due to insurance issues, intravenous antibiotics are often chosen, but oral antibiotics can also achieve good effects, just requiring time (usually 2-3 days orally to reach peak blood concentration). Intravenous administration reaches effective concentrations faster.
Most penicillins and cephalosporins are better used as 1g q8h than 2g bid, as this maintains steadier blood levels and better antimicrobial effect.
Whether to dilute with glucose or saline, and whether to use 100 ml or 250 ml depends on the instructions.
Clinical Experience
Often there are drug shortages, and in each hospital, typically only 2-3 antibiotics per category are available. Review the package inserts of commonly used antibiotics in your hospital; each manufacturer varies. Make a table based on your hospital’s situation.
Example below
| Drug | Target Bacteria | Target Site | Dosage and Administration |
|---|---|---|---|
| Piperacillin/Tazobactam | Most G+, G- sensitive Anaerobes insensitive |
Lung, urinary tract, skin infections, general peritonitis | 3.375g q6h + 250ml NS |
When to Upgrade/Downgrade/Stop Antibiotics
For all infections, obtain cultures based on infection site: sputum, urine, blood, secretions. This guides medication modification; delaying culture until infection worsens is too late.
- Upgrade antibiotics: no improvement after 3 days of treatment, infection continues worsening including blood counts/inflammation markers despite medication
- Change antibiotics: no improvement after 3 days of treatment (based on sensitivity results)
- Downgrade antibiotics: infection improves (and high-level antibiotics have been used for more than 3 days, generally carbapenems downgrade to second- or third-generation cephalosporins or penicillins), and switch to oral medication if appropriate
- Stop antibiotics: infection basically resolved (second- or third-generation cephalosporins or penicillins can usually be stopped directly)
Infection indicators are monitored by routine blood tests (procalcitonin, C-reactive protein)