1. Fulvic acid or its salt as an active ingredient for use to inhibit the growth of bacteria that are resistant to many drugs, or to treat diseases caused by them, where bacteria resistant to many drugs are NDM-1 positive bacteria that produce carbapenemase, or resistant bacteria producing extended-spectrum β-lactamase (ESBL) .2. The fulvic acid or its salt according to claim 1, wherein the multidrug-resistant bacteria are gram-negative bacteria, including, but not limited to, Klebsiella pneumoniae or Escherichia coli. 3. A combination comprising sulfonic acid or its salt as an active ingredient and one or more antibiotics that belong to the class of carbapenems or polymyxin antibiotics for use in the treatment of infections caused by a multidrug-resistant bacterium. 4. The combination of claim 3, wherein the bacteria resistant to multiple drugs are NDM-1 positive bacteria producing carbapenemase. The combination of claim 4, wherein the NDM-1 positive carbapenemase producing bacteria are gram-negative bacteria, including but not limited to Klebsiella pneumoniae or Escherichia coli. 6. The combination of claim 3, wherein the carbapenem is selected from the group consisting of: meropenem, ertapenem, dorupenem, panipenem / betamipron and biapenem, and the polymyxin antibiotic is selected from the group consisting of: colistin sulfate and sodium colistimethate (including sodium colistin methanesulfonate, colistin) .7. Fulvic acid or its salt according to claim 1 or a combination according to claim 3, wherein fulvic acid or its salt is characterized by a pH in the range from acidic1. Фульвовая кислота или ее соль в качестве активного ингредиента для применения для подавления роста бактерий, резистентных к множеству лекарственных средств, или лечения заболеваний, вызванных ими, где бактериями, резистентными к множеству лекарственных средств, являются NDM-1 положительные бактерии, продуцирующие карбапенемазу, или резистентные бактерии, продуцирующие β-лактамазу расширенног
