An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention of such infections. They may either kill or inhibit the growth of bacteria. A limited number of antibiotics also possess antiprotozoal activity. Antibiotics are not effective against viruses such as the ones which cause the common cold or influenza. Drugs which inhibit growth of viruses are termed antiviral drugs or antivirals. Antibiotics are also not effective against fungi. Drugs which inhibit growth of fungi are called antifungal drugs.
Chloramphenicol is an antibiotic useful for the treatment of a number of bacterial infections. This includes use as an eye ointment to treat conjunctivitis. By mouth or by injection into a vein, it is used to treat meningitis, plague, cholera, and typhoid fever. Its use by mouth or by injection is only recommended when safer antibiotics cannot be used. Monitoring both blood levels of the medication and blood cell levels every two days is recommended during treatment.
Gram-negative bacteria are bacteria that, unlike gram-positive bacteria, do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is their cell envelope, which consists of a thin peptidoglycan cell wall sandwiched between an inner (cytoplasmic) membrane and an outer membrane. These bacteria are found in all environments that support life on Earth.
Macrolides are a class of mostly natural products with a large macrocyclic lactone ring to which one or more deoxy sugars, usually cladinose and desosamine, may be attached. The lactone rings are usually 14-, 15-, or 16-membered. Macrolides belong to the polyketide class of natural products. Some macrolides have antibiotic or antifungal activity and are used as pharmaceutical drugs. Rapamycin is also a macrolide and was originally developed as an antifungal, but has since been used as an immunosuppressant drug and is being investigated as a potential longevity therapeutic.
A bacteriostatic agent or bacteriostat, abbreviated Bstatic, is a biological or chemical agent that stops bacteria from reproducing, while not necessarily killing them otherwise. Depending on their application, bacteriostatic antibiotics, disinfectants, antiseptics and preservatives can be distinguished. When bacteriostatic antimicrobials are used, the duration of therapy must be sufficient to allow host defense mechanisms to eradicate the bacteria. Upon removal of the bacteriostat, the bacteria usually start to grow rapidly. This is in contrast to bactericides, which kill bacteria.
Drug resistance is the reduction in effectiveness of a medication such as an antimicrobial or an antineoplastic in treating a disease or condition. The term is used in the context of resistance that pathogens or cancers have "acquired", that is, resistance has evolved. Antimicrobial resistance and antineoplastic resistance challenge clinical care and drive research. When an organism is resistant to more than one drug, it is said to be multidrug-resistant.
This is the timeline of modern antimicrobial (anti-infective) therapy. The years show when a given drug was released onto the pharmaceutical market. This is not a timeline of the development of the antibiotics themselves.
The Actinomycetota are a diverse phylum of Gram-positive bacteria with high GC content. They can be terrestrial or aquatic. They are of great importance to land flora because of their contributions to soil systems. In soil they help to decompose the organic matter of dead organisms so the molecules can be taken up anew by plants. While this role is also played by fungi, Actinomycetota are much smaller and likely do not occupy the same ecological niche. In this role the colonies often grow extensive mycelia, as fungi do, and the name of an important order of the phylum, Actinomycetales, reflects that they were long believed to be fungi. Some soil actinomycetota live symbiotically with the plants whose roots pervade the soil, fixing nitrogen for the plants in exchange for access to some of the plant's saccharides. Other species, such as many members of the genus Mycobacterium, are important pathogens.
A broad-spectrum antibiotic is an antibiotic that acts on the two major bacterial groups, Gram-positive and Gram-negative, or any antibiotic that acts against a wide range of disease-causing bacteria. These medications are used when a bacterial infection is suspected but the group of bacteria is unknown or when infection with multiple groups of bacteria is suspected. This is in contrast to a narrow-spectrum antibiotic, which is effective against only a specific group of bacteria. Although powerful, broad-spectrum antibiotics pose specific risks, particularly the disruption of native, normal bacteria and the development of antimicrobial resistance. An example of a commonly used broad-spectrum antibiotic is ampicillin.
Clindamycin is a lincosamide antibiotic medication used for the treatment of a number of bacterial infections, including osteomyelitis (bone) or joint infections, pelvic inflammatory disease, strep throat, pneumonia, acute otitis media, and endocarditis. It can also be used to treat acne, and some cases of methicillin-resistant Staphylococcus aureus (MRSA). In combination with quinine, it can be used to treat malaria. It is available by mouth, by injection into a vein, and as a cream or a gel to be applied to the skin or in the vagina.
Rickettsia rickettsii is a Gram-negative, intracellular, cocco-bacillus bacterium that was first discovered in 1902. Having a reduced genome, the bacterium harvests nutrients from its host cell to carry out respiration, making it an organo-heterotroph. Maintenance of its genome is carried out through vertical gene transfer where specialization of the bacterium allows it to shuttle host sugars directly into its TCA cycle.
Chloramphenicol acetyltransferase is a bacterial enzyme that detoxifies the antibiotic chloramphenicol and is responsible for chloramphenicol resistance in bacteria. This enzyme covalently attaches an acetyl group from acetyl-CoA to chloramphenicol, which prevents chloramphenicol from binding to ribosomes. A histidine residue, located in the C-terminal section of the enzyme, plays a central role in its catalytic mechanism.
Gray baby syndrome is a rare but serious, even fatal, side effect that occurs in newborn infants following the accumulation of the antibiotic chloramphenicol. Chloramphenicol is a broad-spectrum antibiotic that has been used to treat a variety of bacteria infections like Streptococcus pneumoniae as well as typhoid fever, meningococcal sepsis, cholera, and eye infections. Chloramphenicol works by binding to ribosomal subunits which blocks transfer ribonucleic acid (RNA) and prevents the synthesis of bacterial proteins. Chloramphenicol has also been used to treat neonates born before 37 weeks of the gestational period for prophylactic purposes. In 1958, newborns born prematurely due to rupture of the amniotic sac were given chloramphenicol to prevent possible infections, and it was noticed that these newborns had a higher mortality rate compared with those who were not treated with the antibiotic. Over the years, chloramphenicol has been used less in clinical practice due to the risks of toxicity not only to neonates, but also to adults due to the risk of aplastic anemia. Chloramphenicol is now reserved to treat certain severe bacteria infections that were not successfully treated with other antibiotic medications.
Aeromonas hydrophila is a heterotrophic, Gram-negative, rod-shaped bacterium mainly found in areas with a warm climate. This bacterium can be found in fresh or brackish water. It can survive in aerobic and anaerobic environments, and can digest materials such as gelatin and hemoglobin. A. hydrophila was isolated from humans and animals in the 1950s. It is the best known of the species of Aeromonas. It is resistant to most common antibiotics and cold temperatures and is oxidase- and indole-positive. Aeromonas hydrophila also has a symbiotic relationship as gut flora inside of certain leeches, such as Hirudo medicinalis.
Florfenicol is a fluorinated synthetic analog of thiamphenicol, mainly used as a antibiotic in veterinary medicine.
Pathogenic bacteria are bacteria that can cause disease. This article focuses on the bacteria that are pathogenic to humans. Most species of bacteria are harmless and are often beneficial but others can cause infectious diseases. The number of these pathogenic species in humans is estimated to be fewer than a hundred. By contrast, several thousand species are part of the gut flora present in the digestive tract.
Azidamfenicol is an amphenicol antibiotic, which has similar profile to chloramphenicol. It is used only topically, as eye drops and ointment for treatment of susceptible bacterial infections.
A protein synthesis inhibitor is a compound that stops or slows the growth or proliferation of cells by disrupting the processes that lead directly to the generation of new proteins.
Antimicrobials destroy bacteria, viruses, fungi, algae, and other microbes. The cells of bacteria (prokaryotes), such as salmonella, differ from those of higher-level organisms (eukaryotes), such as fish. Antibiotics are chemicals designed to either kill or inhibit the growth of pathogenic bacteria while exploiting the differences between prokaryotes and eukaryotes in order to make them relatively harmless in higher-level organisms. Antibiotics are constructed to act in one of three ways: by disrupting cell membranes of bacteria, by impeding DNA or protein synthesis, or by hampering the activity of certain enzymes unique to bacteria.
Bicyclomycin (Bicozamycin) is a broad spectrum antibiotic active against Gram-negative bacteria and the Gram-positive bacterium, Micrococcus luteus that was isolated from Streptomyces sapporonesis and Streptomyces aizumenses in 1972. It belongs to a class of naturally occurring 2,5-diketopiperazines, that are among the most numerous of all the naturally occurring peptide antibiotics. This clinically useful antibiotic is rapidly absorbed in humans when given intramuscularly, has low toxicity and has been used to treat diarrhea in humans and bacterial diarrhea in calves and pigs.
