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.
Enterobacter is a genus of common Gram-negative, facultatively anaerobic, rod-shaped, non-spore-forming bacteria of the family Enterobacteriaceae. Cultures are found in soil, water, sewage, feces and gut environments. It is the type genus of the order Enterobacterales. Several strains of these bacteria are pathogenic and cause opportunistic infections in immunocompromised hosts and in those who are on mechanical ventilation. The urinary and respiratory tracts are the most common sites of infection. The genus Enterobacter is a member of the coliform group of bacteria. It does not belong to the fecal coliforms group of bacteria, unlike Escherichia coli, because it is incapable of growth at 44.5 °C in the presence of bile salts. Some of them show quorum sensing properties.
Staphylococcus haemolyticus is a member of the coagulase-negative staphylococci (CoNS). It is part of the skin flora of humans, and its largest populations are usually found at the axillae, perineum, and inguinal areas. S. haemolyticus also colonizes primates and domestic animals. It is a well-known opportunistic pathogen, and is the second-most frequently isolated CoNS. Infections can be localized or systemic, and are often associated with the insertion of medical devices. The highly antibiotic-resistant phenotype and ability to form biofilms make S. haemolyticus a difficult pathogen to treat. Its most closely related species is Staphylococcus borealis.
Staphylococcus saprophyticus is a Gram-positive coccus belonging to the genus Staphylococcus. S. saprophyticus is a common cause of community-acquired urinary tract infections.
Aeromonas veronii is a Gram-negative, rod-shaped bacterium found in fresh water and in association with animals. It can be a pathogen of humans and a beneficial symbiont of leeches. In humans A. veronii can cause diseases ranging from wound infections and diarrhea to sepsis in immunocompromised patients. Humans treated with medicinal leeches after vascular surgery can be at risk for infection from A. veronii and are commonly placed on prophylactic antibiotics. Most commonly ciprofloxacin is used but there have been reports of resistant strains leading to infection. In leeches, this bacterium is thought to function in the digestion of blood, provision of nutrients, or preventing other bacteria from growing.
Klebsiella aerogenes, previously known as Enterobacter aerogenes, is a Gram-negative, oxidase-negative, catalase-positive, citrate-positive, indole-negative, rod-shaped bacterium. Capable of motility via peritrichous flagella, the bacterium is approximately 1–3 microns in length.
Cronobacter is a genus of Gram-negative, facultatively anaerobic, oxidase-negative, catalase-positive, rod-shaped bacteria of the family Enterobacteriaceae. Several Cronobacter species are desiccation resistant and persistent in dry products such as powdered infant formula. They are generally motile, reduce nitrate, use citrate, hydrolyze esculin and arginine, and are positive for L-ornithine decarboxylation. Acid is produced from D-glucose, D-sucrose, D-raffinose, D-melibiose, D-cellobiose, D-mannitol, D-mannose, L-rhamnose, L-arabinose, D-trehalose, galacturonate and D-maltose. Cronobacter spp. are also generally positive for acetoin production and negative for the methyl red test, indicating 2,3-butanediol rather than mixed acid fermentation. The type species of the genus Cronobacter is Cronobacter sakazakii comb. nov.
Morganella morganii is a species of Gram-negative bacteria. It has a commensal relationship within the intestinal tracts of humans, mammals, and reptiles as normal flora. Although M. morganii has a wide distribution, it is considered an uncommon cause of community-acquired infection, and it is most often encountered in postoperative and other nosocomial infections, such as urinary tract infections.
Proteus penneri is a Gram-negative, facultatively anaerobic, rod-shaped bacterium. It is an invasive pathogen and a cause of nosocomial infections of the urinary tract or open wounds. Pathogens have been isolated mainly from the urine of patients with abnormalities in the urinary tract, and from stool. P. penneri strains are naturally resistant to numerous antibiotics, including penicillin G, amoxicillin, cephalosporins, oxacillin, and most macrolides, but are naturally sensitive to aminoglycosides, carbapenems, aztreonam, quinolones, sulphamethoxazole, and co-trimoxazole. Isolates of P. penneri have been found to be multiple drug-resistant (MDR) with resistance to six to eight drugs. β-lactamase production has also been identified in some isolates.
Staphylococcus hyicus is a Gram-positive, facultatively anaerobic bacterium in the genus Staphylococcus. It consists of clustered cocci and forms white circular colonies when grown on blood agar. S. hyicus is a known animal pathogen. It causes disease in poultry, cattle, horses, and pigs. Most notably, it is the agent that causes porcine exudative epidermitis, also known as greasy pig disease, in piglets. S. hyicus is generally considered to not be zoonotic, however it has been shown to be able to cause bacteremia and sepsis in humans.
Aeromonas schubertii is a Gram-negative, rod-shaped bacterium. Its type strain is ATCC 43700. It is differentiated from other species by not metabolising D-mannitol. It is resistant to ampicillin and carbenicillin and susceptible to most other agents. It causes infection in several species, including humans and Channa argus.
Enterobacter taylorae is a Gram-negative bacteria formerly known as Enteric Group 19, and also known as Enterobacter cancerogenus. Strains of E. taylorae are positive for: Voges-Proskauer, citrate utilization, arginine dihydrolase and malonate utilization. They ferment D-glucose and also ferment D-mannitol, L-rhamnose and cellobiose. They are negative for indole production, urea hydrolysis, lysine decarboxylase and fermentation of adonitol, D-sorbitol and raffinose. It occurs in human clinical specimens, being isolated from blood and from spinal fluid. It is known to cause infections and is not susceptible to penicillins nor cephalosporins.
Vibrio furnissii is a Gram-negative, rod-shaped bacterium. Its type strain is ATCC 35016. V. furnissii is aerogenic (gas-producing), and uses L-rhamnose, L-arginine, L-arabinose, maltose, and D-mannitol, but not L-lysine, L-ornithine, or lactose. It has been isolated from patients with gastroenteritis, bacteremia, skin lesions, and sepsis.
Bartonella elizabethae, formerly known as Rochalimaea elizabethae, is a bacterium. As with other Bartonella species, it can cause disease in animals.
Staphylococcus schleiferi is a Gram-positive, cocci-shaped bacterium of the family Staphylococcaceae. It is facultatively anaerobic, coagulase-variable, and can be readily cultured on blood agar where the bacterium tends to form opaque, non-pigmented colonies and beta (β) hemolysis. There exists two subspecies under the species S. schleiferi: Staphylococcus schleiferi subsp. schleiferi and Staphylococcus schleiferi subsp. coagulans.
Staphylococcus pseudintermedius is a gram positive coccus bacteria of the genus Staphylococcus found worldwide. It is primarily a pathogen for domestic animals, but has been known to affect humans as well. S. pseudintermedius is an opportunistic pathogen that secretes immune modulating virulence factors, has many adhesion factors, and the potential to create biofilms, all of which help to determine the pathogenicity of the bacterium. Diagnoses of Staphylococcus pseudintermedius have traditionally been made using cytology, plating, and biochemical tests. More recently, molecular technologies like MALDI-TOF, DNA hybridization and PCR have become preferred over biochemical tests for their more rapid and accurate identifications. This includes the identification and diagnosis of antibiotic resistant strains.
Citrobacter sedlakii is a species of Gram-negative bacteria. It has been described as causing human disease, but is generally found as a non-pathogenic organism in human stools.
Escherichia hermannii is a Gram-negative, rod-shaped species of bacterium. Strains of this species were originally isolated from human wounds, sputum, and stool. The species is named for American microbiologists George J. Hermann and Lloyd G. Herman.
Corynebacterium xerosis is a Gram-positive, rod-shaped bacterium in the genus Corynebacterium. Although it is frequently a harmless commensal organism living on the skin and mucus membranes, C. xerosis is also a clinically-relevant opportunistic pathogen that has been attributed to a number of different infections in animals and humans. However, its actual prominence in human medicine is up for debate due to early difficulties distinguishing it from other Corynebacterium species in clinical isolates.
Corynebacterium striatum is a bacterium that is a member of the Corynebacterium genus. It is classified as non-diphtheritic. The bacterium is a gram-positive prokaryote that assumes a 'club-like' morphology, more formally known as a corynebacteria structure. It is non-lipophilic and undergoes aerobic respiration and is also a facultative anaerobe it is catalase negative and oxidase positive glucose and sucrose fermenter.
