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 rather than antibiotics. They are also not effective against fungi; drugs which inhibit growth of fungi are called antifungal drugs.
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.
The periplasm is a concentrated gel-like matrix in the space between the inner cytoplasmic membrane and the bacterial outer membrane called the periplasmic space in Gram-negative bacteria. Using cryo-electron microscopy it has been found that a much smaller periplasmic space is also present in Gram-positive bacteria, between cell wall and the plasma membrane. The periplasm may constitute up to 40% of the total cell volume of gram-negative bacteria, but is a much smaller percentage in gram-positive bacteria.
Aminoglycoside is a medicinal and bacteriologic category of traditional Gram-negative antibacterial medications that inhibit protein synthesis and contain as a portion of the molecule an amino-modified glycoside (sugar). The term can also refer more generally to any organic molecule that contains amino sugar substructures. Aminoglycoside antibiotics display bactericidal activity against Gram-negative aerobes and some anaerobic bacilli where resistance has not yet arisen but generally not against Gram-positive and anaerobic Gram-negative bacteria.
Tigecycline, sold under the brand name Tygacil, is a tetracycline antibiotic medication for a number of bacterial infections. It is a glycylcycline class drug that is administered intravenously. It was developed in response to the growing rate of antibiotic resistant bacteria such as Staphylococcus aureus, Acinetobacter baumannii, and E. coli. As a tetracycline derivative antibiotic, its structural modifications has expanded its therapeutic activity to include Gram-positive and Gram-negative organisms, including those of multi-drug resistance.
Carbapenems are a class of very effective antibiotic agents most commonly used for treatment of severe bacterial infections. This class of antibiotics is usually reserved for known or suspected multidrug-resistant (MDR) bacterial infections. Similar to penicillins and cephalosporins, carbapenems are members of the beta-lactam antibiotics drug class, which kill bacteria by binding to penicillin-binding proteins, thus inhibiting bacterial cell wall synthesis. However, these agents individually exhibit a broader spectrum of activity compared to most cephalosporins and penicillins. Furthermore, carbapenems are typically unaffected by emerging antibiotic resistance, even to other beta-lactams.
Imipenem is a synthetic β-lactam antibiotic belonging to the carbapenems chemical class. developed by Merck scientists Burton Christensen, William Leanza, and Kenneth Wildonger in the mid-1970s. Carbapenems are highly resistant to the β-lactamase enzymes produced by many multiple drug-resistant Gram-negative bacteria, thus playing a key role in the treatment of infections not readily treated with other antibiotics. It is usually administered through intravenous injection.
In microbiology, the minimum inhibitory concentration (MIC) is the lowest concentration of a chemical, usually a drug, which prevents visible in vitro growth of bacteria or fungi. MIC testing is performed in both diagnostic and drug discovery laboratories.
Cefotiam is a parenteral third-generation cephalosporin antibiotic. It has broad-spectrum activity against Gram-positive and Gram-negative bacteria. As a beta-lactam, its bactericidal activity results from the inhibition of cell wall synthesis via affinity for penicillin-binding proteins.
Beta-lactamases are a family of enzymes involved in bacterial resistance to beta-lactam antibiotics. In bacterial resistance to beta-lactam antibiotics, the bacteria have beta-lactamase which degrade the beta-lactam rings, rendering the antibiotic ineffective. However, with beta-lactamase inhibitors, these enzymes on the bacteria are inhibited, thus allowing the antibiotic to take effect. Strategies for combating this form of resistance have included the development of new beta-lactam antibiotics that are more resistant to cleavage and the development of the class of enzyme inhibitors called beta-lactamase inhibitors. Although β-lactamase inhibitors have little antibiotic activity of their own, they prevent bacterial degradation of beta-lactam antibiotics and thus extend the range of bacteria the drugs are effective against.
Arbekacin (INN) is a semisynthetic aminoglycoside antibiotic which was derived from kanamycin. It is primarily used for the treatment of infections caused by multi-resistant bacteria including methicillin-resistant Staphylococcus aureus (MRSA). Arbekacin was originally synthesized from dibekacin in 1973 by Hamao Umezawa and collaborators. It has been registered and marketed in Japan since 1990 under the trade name Habekacin. Arbekacin is no longer covered by patent and generic versions of the drug are also available under such trade names as Decontasin and Blubatosine.
Solithromycin is a ketolide antibiotic undergoing clinical development for the treatment of community-acquired pneumonia and other infections.
In molecular biology, UDP-3-O-N-acetylglucosamine deacetylase, EC 3.5.1.-, is a bacterial enzyme involved in lipid A biosynthesis.
UDP-3-O-acyl-N-acetylglucosamine deacetylase, also known as LpxC, is a zinc-dependent enzyme involved in bacterial lipid A biosynthesis, catalyzing the removal of the acetyl group from UDP-3-O-acyl-N-acetylglucosamine, a key step in the production of lipopolysaccharides in the outer membrane of Gram-negative bacteria.
Avibactam is a non-β-lactam β-lactamase inhibitor developed by Actavis jointly with AstraZeneca. A new drug application for avibactam in combination with ceftazidime was approved by the FDA on February 25, 2015, for treating complicated urinary tract (cUTI) and complicated intra-abdominal infections (cIAI) caused by antibiotic resistant-pathogens, including those caused by multi-drug resistant Gram-negative bacterial pathogens.
Ceftolozane/tazobactam, sold under the brand name Zerbaxa, is a fixed-dose combination antibiotic medication used for the treatment of complicated urinary tract infections and complicated intra-abdominal infections in adults. Ceftolozane is a cephalosporin antibiotic, developed for the treatment of infections with gram-negative bacteria that are resistant to conventional antibiotics. It was studied for urinary tract infections, intra-abdominal infections and ventilator-associated bacterial pneumonia.
Antivirulence is the concept of blocking virulence factors. In regards to bacteria, the idea is to design agents that block virulence rather than kill bacteria en masse, as the current regime results in much more selective pressure.
ESKAPE is an acronym comprising the scientific names of six highly virulent and antibiotic resistant bacterial pathogens including: Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp. The acronym is sometimes extended to ESKAPEE to include Escherichia coli. This group of Gram-positive and Gram-negative bacteria can evade or 'escape' commonly used antibiotics due to their increasing multi-drug resistance (MDR). As a result, throughout the world, they are the major cause of life-threatening nosocomial or hospital-acquired infections in immunocompromised and critically ill patients who are most at risk. P. aeruginosa and S. aureus are some of the most ubiquitous pathogens in biofilms found in healthcare. P. aeruginosa is a Gram-negative, rod-shaped bacterium, commonly found in the gut flora, soil, and water that can be spread directly or indirectly to patients in healthcare settings. The pathogen can also be spread in other locations through contamination, including surfaces, equipment, and hands. The opportunistic pathogen can cause hospitalized patients to have infections in the lungs, blood, urinary tract, and in other body regions after surgery. S. aureus is a Gram-positive, cocci-shaped bacterium, residing in the environment and on the skin and nose of many healthy individuals. The bacterium can cause skin and bone infections, pneumonia, and other types of potentially serious infections if it enters the body. S. aureus has also gained resistance to many antibiotic treatments, making healing difficult. Because of natural and unnatural selective pressures and factors, antibiotic resistance in bacteria usually emerges through genetic mutation or acquires antibiotic-resistant genes (ARGs) through horizontal gene transfer - a genetic exchange process by which antibiotic resistance can spread.
Murepavadin also known as POL7080 is a Pseudomonas specific peptidomimetic antibiotic. It is a synthetic cyclic beta hairpin peptidomimetic based on the cationic antimicrobial peptide protegrin I (PG-1) and the first example of an outer membrane protein-targeting antibiotic class with a novel, nonlytic mechanism of action, highly active and selective against the protein transporter LptD of Pseudomonas aeruginosa. In preclinical studies the compound was highly active on a broad panel of clinical isolates including multi-drug resistant Pseudomonas bacteria with outstanding in vivo efficacy in sepsis, lung, and thigh infection models. Intravenous murepavadin is in development for the treatment of bacterial hospital-acquired pneumonia and bacterial ventilator-associated pneumonia due to Pseudomonas aeruginosa.
Cefiderocol, sold under the brand name Fetroja among others, is an antibiotic used to treat complicated urinary tract infections when no other options are available. It is indicated for the treatment of multi-drug-resistant Gram-negative bacteria including Pseudomonas aeruginosa. It is given by injection into a vein.
