There are three types of antibiotic resistance. The first is innate (natural) antibiotic resistance as a characteristic of a particular strain, species or whole family of bacteria that are naturally insensitive to the effects of an antibiotic. The second type is acquired antibiotic resistance. This occurs as a result of excessive or too frequent use of an antibiotic, resulting in changes to the bacterial genome. These can be down to mutations in the aforementioned genome or can result from the acquisition of a resistance gene, which happens most frequently. The third type of antibiotic resistance is cross-resistance. This is a case where bacterial resistance to one antibiotic or group of antibiotics implies resistance to other antibiotics in that group or with a similar mechanism of action. (Source: E-biotechnologia.pl)
