Antibacterial Drugs are antimicrobial substances that are active against bacteria and are used to treat bacterial infections in humans.

Antibacterial drugs are the most commonly used antibacterial medicines in current medical practice. They are also the most common type of preventive medical drug for the prevention and treatment of infections. They can either inhibit or kill the growth of infectious bacteria. Antibacterial drugs come under three major classes include broad-spectrum, systemic, and special medication. Broad-spectrum antibiotics are considered to be the best type of antibacterial drugs as they are effective in fighting both good and bad bacteria in the body. Systemic antibiotics are prescribed by doctors for use in the entire body, to eliminate the whole organism, including the blood, urinary tract, skin, digestive tract, and some oral infections. The special medication class includes quinolones, which belong to the benzoyl peroxide family, and are prescribed against several diseases and health disorders. Common examples of quinolones include ciprofloxacin and trimethoprim/ethidium.

Antibacterial drugs act by killing microorganisms by preventing their reproduction. These drugs affect the DNA of the bacteria thereby preventing them from producing duplicate offspring. Some examples of DNA-binding inhibitors include trimethoprim/ethidium and flucytosine. The DNA-binding inhibitors are usually synthesized by exposing DNA to specific amino acids which initiate the formation of a complementary DNA sequence. Examples of DNA-binding inhibitors include trimethoprim, gentamycin, nalidixic, miconazole, ketoconazole, indomethacin, azithromycin, and sulfamethoxazole. Resistance to antibacterial drugs develops when the concentration of the drug in culture is lower than that required in therapeutic doses. This results in the development of antibiotic-resistant strains of bacteria. To counter this, drugs have been introduced into the culture system through mutation. Resistance mutations in the bacteria develop when they are exposed to certain antibiotics in high-throughput screening tests. Resistance mutations in some strains develop even when antibiotics are used after the introduction of resistance genetic markers.

Gram-negative bacteria are those that do not produce any sulfates (gas-producing compounds). The most common resistant strains are those that produce sulfated cystine or glycogen. The production of sulfates results in a shift of the microbial metabolism towards anaerobic glycolysis. Anaerobic glycolysis causes a high degree of glycolysis in nonbacterial cells. As a result of this, Gram-negative bacteria are prone to urinary tract infections and infections of the kidneys. Subsequently, the antibiotics are ineffective against these strains and Gram-negative bacteria have to be given oral medications. Other antibiotics like metronidazole and fluconazole have different metabolic pathways. Metronidazole produces hydrogen sulfide. This compound generates a gas that irritates the lining of the bladder. Metronidazoles also inhibits the formation of ergosterol. Ergosterol is produced by the ergosterol synthetase. This prevents the degradation of proteins and the release of amino acids.

The cytoplasmic membrane of bacteria is located between the plasma membranes of the bacteria and the cell wall. Drugs like chlorhexidine gluconate (Chloroquine) bind with the cytoplasmic membrane and stop the secretion of neurotransmitters like acetylcholine. The amine biphosphate pathway results in the breakdown of the cytoplasmic membrane. Amino-proteins and other molecules involved in protein synthesis are substrates of this pathway. Antibacterial drugs have found use in many health-related problems. Some of these drugs have been developed specifically for use against Gram-negative bacteria that produce sulfur compounds. Some of these drugs are in development for use against some of the environmental toxin-resistant species, including some of the clinical isolates of E. coli. There is still much research to be done on these new antibiotics and their antibacterial agents, but the scientists are all excited about the prospects for new medicines that will make our lives better and safer.