In this case, many factors are taken into account: the absorption of the drug in the gastrointestinal tract, the state of the digestive system as a whole (in some diseases, the absorption rate decreases, and the effectiveness of treatment decreases). Some drugs can only be administered one way.
After performing a sensitivity analysis, the doctor has the opportunity to change the drug to a more effective one. Replacement of the drug can be made even in the absence of the effect of treatment for 3-5 days.
Etiotropic (erythromycin) prescription of antibiotics is more effective. In this case, it turns out what caused the disease - with the help of bacteriological research, the type of pathogen is established. Then the doctor selects a specific drug to which the microbe has no resistance (resistance).
Antibiotics erythromycin work only on bacteria and fungi! Unicellular microorganisms are considered bacteria. There are several thousand species of bacteria, some of which coexist quite normally with humans - more than 20 species of bacteria live in the large intestine.
Some bacteria are conditionally pathogenic - they become the cause of the disease only under certain conditions, for example, when they enter an atypical habitat for them. For example, very often prostatitis is caused by E. coli, which enters the ascending way into the prostate from the rectum.