Beta-lactamases (β-lactamases) are enzymes produced by bacteria that provide multi-resistance to beta-lactam antibiotics such as penicillins, cephalosporins, cephamycins, monobactams and carbapenems (ertapenem), although carbapenems are relatively resistant to beta-lactamase. Beta-lactamase provides antibiotic resistance by breaking the antibiotics' structure. These antibiotics all have a common element in their molecular structure: a four-atom ring known as a beta-lactam (β-lactam) ring. Through hydrolysis, the enzyme lactamase breaks the β-lactam ring open, deactivating the molecule's antibacterial properties.
Severe acute respiratory syndrome–related coronavirus is a species of virus consisting of many known strains phylogenetically related to severe acute respiratory syndrome coronavirus 1 (SARS-CoV-1) that have been shown to possess the capability to infect humans, bats, and certain other mammals. These enveloped, positive-sense single-stranded RNA viruses enter host cells by binding to the angiotensin-converting enzyme 2 (ACE2) receptor. The SARSr-CoV species is a member of the genus Betacoronavirus and of the subgenus Sarbecovirus.
Pseudomonas is a genus of Gram-negative bacteria belonging to the family Pseudomonadaceae in the class Gammaproteobacteria. The 313 members of the genus demonstrate a great deal of metabolic diversity and consequently are able to colonize a wide range of niches. Their ease of culture in vitro and availability of an increasing number of Pseudomonas strain genome sequences has made the genus an excellent focus for scientific research; the best studied species include P. aeruginosa in its role as an opportunistic human pathogen, the plant pathogen P. syringae, the soil bacterium P. putida, and the plant growth-promoting P. fluorescens, P. lini, P. migulae, and P. graminis.
Acinetobacter is a genus of Gram-negative bacteria belonging to the wider class of Gammaproteobacteria. Acinetobacter species are oxidase-negative, exhibit twitching motility, and occur in pairs under magnification.
Colistin, also known as polymyxin E, is an antibiotic medication used as a last-resort treatment for multidrug-resistant Gram-negative infections including pneumonia. These may involve bacteria such as Pseudomonas aeruginosa, Klebsiella pneumoniae, or Acinetobacter. It comes in two forms: colistimethate sodium can be injected into a vein, injected into a muscle, or inhaled, and colistin sulfate is mainly applied to the skin or taken by mouth. Colistimethate sodium is a prodrug; it is produced by the reaction of colistin with formaldehyde and sodium bisulfite, which leads to the addition of a sulfomethyl group to the primary amines of colistin. Colistimethate sodium is less toxic than colistin when administered parenterally. In aqueous solutions it undergoes hydrolysis to form a complex mixture of partially sulfomethylated derivatives, as well as colistin. Resistance to colistin began to appear as of 2015.
The bacterial capsule is a large structure common to many bacteria. It is a polysaccharide layer that lies outside the cell envelope, and is thus deemed part of the outer envelope of a bacterial cell. It is a well-organized layer, not easily washed off, and it can be the cause of various diseases.
Cystovirus is a genus of double-stranded RNA viruses which infects bacteria. It is the only genus in the family Cystoviridae. The name of the group cysto derives from Greek kystis which means bladder or sack. There are seven species in this genus.
Lipid A is a lipid component of an endotoxin held responsible for the toxicity of gram-negative bacteria. It is the innermost of the three regions of the lipopolysaccharide (LPS), also called endotoxin molecule, and its hydrophobic nature allows it to anchor the LPS to the outer membrane. While its toxic effects can be damaging, the sensing of lipid A by the immune system may also be critical for the onset of immune responses to gram-negative infection, and for the subsequent successful fight against the infection.
Carbapenems are a class of very effective antibiotic agents most commonly used for the 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.
Acinetobacter calcoaceticus is a bacterial species of the genus Acinetobacter. It is a nonmotile, Gram-negative coccobacillus. It grows under aerobic conditions, is catalase positive and oxidase negative. A. calcoaceticus is a part of the A. calcoaceticus-A. baumannii complex together with Acinetobacter baumannii, Acinetobacter nosocomialis, Acinetobacter pitti and Acinetobacter seifertii.
Acinetobacter baumannii is a typically short, almost round, rod-shaped (coccobacillus) Gram-negative bacterium. It is named after the bacteriologist Paul Baumann. It can be an opportunistic pathogen in humans, affecting people with compromised immune systems, and is becoming increasingly important as a hospital-derived (nosocomial) infection. While other species of the genus Acinetobacter are often found in soil samples, it is almost exclusively isolated from hospital environments. Although occasionally it has been found in environmental soil and water samples, its natural habitat is still not known.
Acinetobacter venetianus is a species of bacteria notable for degrading n-alkanes. It harbours plasmids carrying sequences similar to the Pseudomonas oleovorans alkane hydroxylase gene alkBFGH. Its potential for bioremediation is an active research topic, particularly its role in the production of the bioemulsifier emulsan. Its type strain is RAG-1T(=ATCC 31012T=CCUG 45561T=LMG 19082T=LUH 3904T=NIPH 1925T).
Acinetobacter haemolyticus is a species of bacterium. Its type strain is ATCC 17906. It is potentially pathogenic.
Acinetobacter junii is a species of bacteria. Its type strain is ATCC 17908. It can be pathogenic. This bacterium has been linked to nosocomial infections including catheter-related blood stream infections and cellulitis.
Acinetobacter ursingii is a species of potentially pathogenic bacteria. Its type strain is LUH 3792T.
Acinetobacter schindleri is a species of bacteria. It is potentially pathogenic. Its type strain is LUH 5832T.
Lactobacillus iners is a species in the genus Lactobacillus. It is a Gram-positive, catalase-negative, facultatively anaerobic rod-shaped bacterium with type strain CCUG 28746T. Lactobacillus iners is a normal inhabitant of the lower reproductive tract in healthy women.
Acinetobacter nosocomialis is a gram-negative, strictly aerobic bacterium from the genus Acinetobacter isolated from a patient at MetroHealth in Cleveland, Ohio. Acinetobacter nosocomialis belongs to the Acinetobacter calcoaceticus-baumannii complex.
Acinetobacter soli is a Gram-negative, catalase-positive, oxidase-negative, strictly aerobic rod-shaped, nonmotile bacterium from the genus Acinetobacter isolated from forest soil at Mt. Baekwoon in the Republic of Korea. . Acinetobacter soli can cause bloodstream infection in neonates.
Acinetobacter baylyi is a bacterial species of the genus Acinetobacter, which was discovered in activated sludge in Victoria, Australia alongside six other new Acinetobacter species. A. baylyi is named after Ronald Bayly, an Australian microbiologist. As with other species of Acinetobacter it is a nonmotile, gram negative coccobacillus. It grows under aerobic conditions, is catalase positive and oxidase negative. The species is natural competent, meaning that it can take up exogenous DNA from its surroundings and incorporate the DNA into its own chromosomal DNA by transformation (genetics).
