In 1928 the American Fleming by chance discovered that ordinary bread mold (penicillium notatum) inhibits the growth of bacteria. With that the first antibiotic, penicillin, was discovered and Fleming got the Nobel Prize in 1945. (By the way, even in ancient Egypt moldy bread was a remedy; but this is absolutely not recommended for imitation. There are also very toxic molds!)
Over time, more antibiotics were discovered and their success was gigantic. Previously fatal diseases such as tuberculosis, diphtheria, typhoid, cholera, meningitis or pneumonia were now curable. Amputations decreased dramatically because infected injuries could be healed by antibiotics.

Why are naturopathic doctors against the use of antibiotics?
A reputable doctor or therapist will never be totally against the use of antibiotics, but always against exaggerated and too careless use of them because antibiotics can also damage.
How can this wonder weapon against bacteria (and only against bacteria, never against viral diseases such as influenza) be harmful?
There are many reasons. Not all bacteria are harmful, many are important helpers in our organism, for example, in the intestine, where they can help us with the digestion of food and even produce vitamins. Because antibiotics are "blind" and cannot distinguish between good and harmful bacteria, even helpful bacteria are killed in the intestine. While taking antibiotics, diarrhea frequently occurs. A long-term consequence is a possible overgrowth of the intestines with harmful bacteria and fungi. Therefore, antibiotic therapy should be accompanied by intestinal protective agents and immediately afterwards followed by a gut renovation. There even exists a very dangerous bacterial overgrowth of the intestine, a clostridial infection.
Resistance means that antibiotics have become ineffective in the treatment against bacteria. Through careless use of antibiotics, these resistances are increasing dramatically worldwide.

The consequences: If you are suffering from a MRSA infection (Multiresistant Staph. aureus bacteria), some hospitals will treat you only in an emergency. In German nursing homes, the affected patient is isolated from all other residents; the disease has to be reported. Meanwhile, in Russia and America tuberculosis is spreading again, and antibiotics are no longer effective. As I said, these are homemade problems caused by an incorrect use of antibiotics.
Side effects of antibiotics can include heavy allergies, liver and kidney damage, sun intolerance (never be in direct sunlight for a long time when under antibiotic therapy!), diarrhea, tooth decay, etc.

Are there alternatives to antibiotics?
Yes and no! Certainly not for severe bacterial infections. However, there are some examples in natural medicine which show amazing results. Because why over millions of years only mushrooms should have developed a strategy against bacteria? Here are some examples from naturopathy:

A drug made from broccoli (sulforaphane) kills the pathogens that are responsible for stomach ulcers. The same applies to the licorice root, from which licorice is derived. But people who have high blood pressure need to be careful with licorice, it increases the blood pressure.
Tea tree oil is a natural antibiotic, which also may be useful in foot and nail fungal infections (foot bath with 10 drops of tea tree oil in 3-4 liters of water).
Grapefruit seed extract is effective against 800 different bacteria and, moreover, even against numerous fungi. It is effective and side effect-minimal against intestinal fungi (Candida).
St. John's wort also kills bacteria. Mouthwashes with tea but also wet compresses for skin infections are helpful. It even works against the dreaded MRSA infections.
Nasturtium and bearberry leaves are very effective in urinary tract infections. The ingredients of bearberry leaves also kill the intestinal fungus Candida.
An active ingredient of garlic, allicin, works antibacterial even in a dilution of 1: 250,000. During the world wars, the juice was often used for wound treatment.
Watercress unfolds for hours antibacterial properties along the entire route of the urinary tract. For this, it is enough to consume 20 grams of watercress.
Onions and garlic also act against bacteria. In folk medicine, onion bags have always been applied for otitis.
Thyme is a secret tip among natural antibiotics.

Man also produces antibiotic substances even by himself, these occur for example in sweat and in tears fluid.