The colonization of Propionibacterium acnes in the pathogenesis of acne vulgaris is considered to be one of the important factors in the formation of the inflammatory response in acne, and therefore antibiotics occupy a more important position in acne treatment. With a clearer understanding of the role of Propionibacterium acnes in the pathogenesis of acne and an increasing number of clinical studies showing that the strategy of systemic antimicrobial therapy needs to be changed. 1. Advocate for a reduction in the daily dose of antimicrobial drugs Early studies concluded that live Propionibacterium acnes plays a more important role in inducing the formation of acne inflammation than dead bacteria, and that once Propionibacterium acnes develops drug resistance, it is easy to fail treatment. Therefore, in the past guideline development, the daily dose of doxycycline or minocycline was emphasized to be no less than 100 mg, and even 200 mg was required to effectively kill Propionibacterium acnes and prevent the occurrence of drug resistance when used at low doses. As research progressed, it was found that the inflammation triggered by Propionibacterium acnes is non-quantity-dependent, much less an infectious inflammation, but rather triggers an immune-mediated inflammatory response in the body through its bacterial components, especially the natural immune response induced appears to be more important in the development of acne. Therefore, in the treatment of acne, it is more important to emphasize the anti-inflammatory effect than the antibacterial effect. One study found that daily oral doxycycline 40 mg or minocycline 50 mg was similar in efficacy to a daily dose of 100 mg. Not only were adverse effects significantly reduced with lower doses of both drugs, but it was also difficult to induce bacterial resistance because no definite antibacterial effect was produced in the low-dose situation. Considering that the anti-inflammatory effect of tetracycline antibacterial drugs is better than macrolides, they should usually be preferred in the absence of clear contraindications. 2, advocate the need to shorten the course of antibacterial drugs Previously, it was believed that Propionibacterium acnes has a long reproductive cycle and is an inert anaerobic colonizing bacteria, in which case the antibacterial course of treatment needs to be 3 months, or even extended to 4 months if effective, to prevent drug resistance from arising. It is now considered unnecessary to completely kill Propionibacterium acnes colonized in the skin, and studies have confirmed that a shorter course of treatment is not a detriment to efficacy or to disease recurrence. For this reason, the international acne guidelines emphasize a shorter course of antimicrobial medication to about 1 month. Such a short course of antimicrobial therapy, especially in low doses, can effectively control the inflammatory response on the one hand, and on the other hand, avoid the adverse reactions and bacterial resistance generated by long-term unprincipled use. 3, avoid unreasonable antibacterial therapy The use of antimicrobial drugs should avoid the following unreasonable use: ① The choice of drugs is unreasonable, due to the emphasis on the anti-inflammatory effect of drugs and effective access to the hair follicle sebaceous gland site, it is reasonable to give priority to tetracyclines, while it is obviously unreasonable to give priority to macrolides, except for children under 12 years of age, pregnant women or patients who cannot tolerate tetracyclines. It is also not advocated to routinely select quinolones, and it is clear that this class of drugs, although safer than tetracyclines or macrolide antibiotics, have weaker anti-inflammatory effects, lower concentrations in the sebaceous glands, and are prone to resistance to multiple bacteria with frequent use, affecting the choice of antibacterial drugs in systemic infections. ② Long-term single topical antibacterial drugs; ③ Topical antibacterial drugs combined with oral antibacterial drugs; ④ Do not advocate the routine use of tetracyclines in combination with isotretinoin, the combination of the two has the risk of inducing benign intracranial pressure increase and liver damage; ⑤ Already exist or prone to dysbiosis such as Candida vaginitis and other patients, should not use broad-spectrum antibacterial drugs. 4, pay attention to the adverse reactions of antibacterial drugs There are a variety of adverse reactions to antibacterial drugs, use is should pay attention to. Common ones include gastrointestinal reactions, drug rash, liver damage, photosensitivity reactions, vestibular involvement (such as dizziness, vertigo) and benign intracranial pressure elevation disorder (such as headache, etc.). Rare adverse reactions include lupus-like syndrome, especially when applying minocycline. It should be used with caution or prohibited in patients with long-term alcohol consumption, hepatitis B, photosensitive dermatitis, etc. Tetracyclines should not be used in pregnant women, nursing mothers and children under 16 years of age. Macrolide antibiotics may be considered for children under 16 years of age. Dividing the daily dose of minocycline into oral doses or using an extended-release dosage form to be taken once a night may partially reduce adverse reactions. The drug should be discontinued promptly and treated symptomatically in case of serious adverse reactions or if the patient cannot tolerate it. Macrolides and tetracyclines are prone to drug interactions, combined with other systemic drug therapy to pay attention to drug interactions. 5. Non-antibacterial drugs can replace antibacterial drugs to control the inflammatory process. Propionibacterium acnes runs through all aspects of acne lesion formation, and the dense lesion condition is an important condition for bacterial reproduction. For example, oral administration of retinoids can improve the abnormal keratinization of hair follicle ducts, reduce oil secretion, and discourage bacterial growth. Since the anti-inflammatory effect is more important than the antibacterial effect, some drugs with anti-inflammatory effect such as isotretinoin and Chinese medicine can be chosen instead of necessarily antibacterial drugs. Some non-pharmacological treatments such as photodynamic therapy, red and blue light irradiation, and laser treatment can also achieve the purpose of killing bacteria and controlling inflammation. In conclusion, with the understanding of the pathogenesis of acne, the concept of traditional antibacterial therapy is changing.