Uncle Shen is 65 years old this year. He is not too old, but has many problems. 11 years ago, nasopharyngeal carcinoma metastasized to the lymph nodes, and he was cured after radiotherapy and chemotherapy. He has a history of hypertension, cerebral infarction, and carotid artery occlusion stent placement. Two years ago, he was found to have lymph node metastasis of lung squamous cell carcinoma. After chemotherapy, his condition was controlled and stabilized, but this year, intrapulmonary metastases have appeared. Over the past month, Mr. Shen has had repeated fever, sometimes low fever, sometimes high fever, irregular, taking a lot of antibiotics, and going to the clinic for fluid infusion, but still no improvement, he had to be hospitalized for further examination and treatment, after repeated sputum culture, sputum smear. , No pathogenic bacteria were found in blood culture, tuberculosis was ruled out, and finally, bronchoscopy and NGS testing of bronchoalveolar lavage fluid were performed, and finally the “culprit” – methicillin-resistant Staphylococcus was found. This name may not be known to many people, but as long as you remember one thing, this is the notorious “superbug”.
Penicillin saved countless wounded in World War II, and the invention of penicillin has a lot to do with Staphylococcus. Fleming found some cocci in his Staphylococcus aureus petri dish. was killed, and penicillin was discovered. However, with the widespread use of penicillin for decades, some Staphylococcus aureus can produce penicillinase, which can hydrolyze the β-lactam ring, thus showing resistance to penicillin. As a result, scientists have developed a semi-synthetic penicillin that is resistant to penicillinase, namely methicillin. However, bacteria are constantly evolving. In 1961, British scientist Jevom first discovered methicillin-resistant Staphylococcus aureus, or MRSA for short. MRSA is one of the clinical “super bacteria” and is an important cause of nosocomial and community infections. pathogenic bacteria.
How difficult is MRSA?
Methicillin-resistant Staphylococcus is called a superbug mainly because of its broad-spectrum drug resistance. Except for methicillin resistance, it is resistant to all methicillin-related Both β-lactam and cephalosporin antibiotics with the same structure are resistant. MRSA can also change the target site of antibiotics, produce modified enzymes, reduce membrane permeability, and produce a large amount of p-aminobenzoic acid, p-aminoglycosides, macrocyclic intracellular Esters, tetracyclines, fluoroquinolones, sulfonamides, and rifampicin have different degrees of resistance.
This broad-spectrum drug-resistant bacteria is highly pathogenic and can cause skin and soft tissue infections, blood infections, and infections of various organs in the body, causing sepsis, infective endocarditis , osteomyelitis, arthritis, pneumonia, empyema, lung abscess, meningitis and other serious diseases.
Is there any drug treatment for the superbug of MRSA?
For methicillin-resistant Staphylococcus aureus, you can choose vancomycin, norvancomycin, teicoplanin, linezolid, etc., as well as the new drug daptomycin. MASA generally prefers vancomycin, but if there is renal insufficiency, or the elderly have hearing problems, vancomycin should be avoided and teicoplanin can be used instead. Teicoplanin has a weaker effect than vancomycin, but it is relatively safe for the kidneys. The disadvantage is that it cannot penetrate the blood-brain barrier, so the central nervous system infection cannot be used. instead. Linezolid can cross the blood-brain barrier and the concentration in the lungs is relatively high, so linezolid can be considered for central nervous system infections and pulmonary infections. However, in MASA-induced lung infections, the use of daptomycin has no effect, because the active substance in the alveoli can hydrolyze daptomycin.
Bacteria are constantly evolving just like viruses are constantly mutating. Bacteria are resistant to a variety of antibiotics. One of the reasons is the widespread clinical use of antibiotics, and the abuse of antibiotics is accelerating bacterial resistance. process. Worldwide, antibiotic resistance is rising to dangerous levels. In the past 10 years, the country has taken a series of powerful measures to strictly control the use of antibiotics, the purpose of which is to prevent us from facing a situation of no drugs available in the future.