Elizabethkingia meningoseptica | |
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Wet raised colonies with clear margin and characteristic smell after culturing on blood agar, bacteria plated in this way may not show yellow color. Vancomycin sensitivity (clearing around disk) and colistin resistance may lead to mistaking this organism as Gram-positive. | |
Scientific classification | |
Domain: | Bacteria |
Phylum: | Bacteroidota |
Class: | Flavobacteriia |
Order: | Flavobacteriales |
Family: | Weeksellaceae |
Genus: | Elizabethkingia |
Species: | E. meningoseptica |
Binomial name | |
Elizabethkingia meningoseptica (King, 1959) Kim et al., 2005 | |
Synonyms | |
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Elizabethkingia meningoseptica is a Gram-negative, rod-shaped bacterium widely distributed in nature (e.g. fresh water, salt water, or soil). It may be normally present in fish and frogs; it may be isolated from chronic infectious states, as in the sputum of cystic fibrosis patients. In 1959, American bacteriologist Elizabeth O. King (who isolated Kingella kingae in 1960) was studying unclassified bacteria associated with pediatric meningitis at the Centers for Disease Control and Prevention in Atlanta, when she isolated an organism (CDC group IIa) that she named Flavobacterium meningosepticum (Flavobacterium means "the yellow bacillus" in Latin; meningosepticum likewise means "associated with meningitis and sepsis"). [1] In 1994, it was reclassified in the genus Chryseobacterium and renamed Chryseobacterium meningosepticum [2] (chryseos = "golden" in Greek, so Chryseobacterium means a golden/yellow rod similar to Flavobacterium). In 2005, a 16S rRNA phylogenetic tree of Chryseobacteria showed that C. meningosepticum along with C. miricola (which was reported to have been isolated from Russian space station Mir in 2001 and placed in the genus Chryseobacterium in 2003 [3] ) were close to each other but outside the tree of the rest of the Chryseobacteria and were then placed in a new genus Elizabethkingia named after the original discoverer of F. meningosepticum. [4]
Two species of Elizabethkingia have recently been found to be abundant on the leaf and root surfaces of the tropical tree Gnetum gnemon in Malaysia. [5] Their role in the biology of the plant is unknown. Several other species of tropical trees studied did not have Elizabethkingia present on their leaves or roots, suggesting a host-specific relationship with Gnetum.[ citation needed ]
Under a microscope, E. meningoseptica appears as slender, slightly curved rods which are nonmotile and are negative by Gram stain. They do not form spores, and require oxygen to survive. E. meningoseptica is positive by the catalase test, the oxidase test, and the indole test. It is negative by the urease test. In general, it is negative by the nitrate reductase test, although some strains are positive. [6]
E. meningoseptica grows well on blood agar and chocolate agar. Colonies are very pale yellow and may not be easily evident at 24 hours. Strains growing better at 40 °C are mostly associated with invasive meningitis. [7] Often, a greyish discoloration is seen around the colonies on blood agar due to proteases and gelatinase. E. meningoseptica grows poorly on MacConkey agar and is considered a glucose oxidizer. [8] Most strains do not grow on colistin nalidixic acid agar because, although they are resistant to colistin, they are susceptible to quinolones such as nalidixic acid.[ citation needed ]
E. meningoseptica may show colistin-resistant and vancomycin-sensitive growth, which is paradoxic for a Gram-negative bacterium, but resembles Burkholderia cepacia , which is also a nonfermenter and does not grow well on MacConkey agar. These two can be distinguished by the indole test or the Pyr test, both of which should be clearly negative for B. cepacia and positive for E. meningoseptica. Automated bacterial identification system results should be observed with caution, especially when a patient with Gram-negative bacteremia does not improve with broad-spectrum antibiotic therapy, because several bacteria, including Aeromonas salmonicida (mistaken by ID32 GN [6] ) and Sphingobacterium spp. (mistaken by Vitek 2 [9] ), may be confused with this bacterium, especially the atypical ones. However, unlike many other Aeromonas species such as A. hydrophila and A. punctata, A. salmonicida is indole negative, which can help in distinguishing it in doubtful cases. An automated but so far relatively reliable Rapid NF plus system and API Zym systems use an array of biochemical tests for better identification of nonfermenters and other bacteria and can specifically identify E. meningoseptica.[ citation needed ]
E. meningoseptica predominantly causes outbreaks of meningitis in premature newborns and infants in neonatal intensive care units of underdeveloped countries.[ citation needed ]
Some of the outbreaks have been linked to sources such as contaminated lipid stock bottles, contaminated venous catheter lines and nutritional solution, and tap water. The bacterium is also a rare cause of nosocomial pneumonia, endocarditis, postoperative bacteremia, and meningitis in immunocompromised adults. Only recently has it also been found to cause soft-tissue infection and sepsis in the immunocompetent [9] and in a case of a fatal necrotizing fasciitis in a diabetic patient. [10]
Some 48 cases of Elizabethkingia infection resulting in 17 fatalities were reported in Wisconsin over a 5-month period beginning in November 2015. [11]
This bacterium is usually multiresistant to antibiotics typically prescribed for treating Gram-negative bacterial infections, including extended-spectrum beta-lactam agents (due to production by most strains of two betalactamases: one ESBL and one class B carbapenem-hydrolyzing metallolactamase), aminoglycosides, tetracycline, and chloramphenicol. Though vancomycin has been used in the past, its high Minimum inhibitory concentration (16 μg/mL) has led to a search for alternatives, especially for meningitis. Presently, ciprofloxacin, minocycline, trimethoprim-sulfamethoxazole, rifampin, and novobiocin are considered good alternatives. Most of these are classic drugs for Gram-positive bacteria and not routinely tested on Gram-negative bacteria. [12]
Hypoalbuminemia, increased pulse rate at the onset of infection, and central venous line infection were associated with a poor outcome. [13]
At the 2006 meeting of the International Committee on Systematics of Prokaryotes, the organization's subcommittee on the taxonomy of Flavobacterium and Cytophaga-like bacteria named J.-F. Bernardet and B. Bruun as two key authorities on this bacterium. [14]
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.
Proteus mirabilis is a Gram-negative, facultatively anaerobic, rod-shaped bacterium. It shows swarming motility and urease activity. P. mirabilis causes 90% of all Proteus infections in humans. It is widely distributed in soil and water. Proteus mirabilis can migrate across the surface of solid media or devices using a type of cooperative group motility called swarming. Proteus mirabilis is most frequently associated with infections of the urinary tract, especially in complicated or catheter-associated urinary tract infections.
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.
Streptococcus bovis is a group of strains of Gram-positive bacteria, originally described as a species, that in humans is associated with urinary tract infections, endocarditis, sepsis, and colorectal cancer. S. bovis is commonly found in the alimentary tract of cattle, sheep, and other ruminants, and may cause ruminal acidosis. It is also associated with spontaneous bacterial peritonitis, a frequent complication occurring in patients affected by cirrhosis. Equivalence with Streptococcus equinus has been contested.
Capnocytophaga canimorsus is a fastidious, slow-growing, Gram-negative rod of the genus Capnocytophaga. It is a commensal bacterium in the normal gingival microbiota of canine and feline species, but can cause illness in humans. Transmission may occur through bites, licks, or even close proximity with animals. C. canimorsus generally has low virulence in healthy individuals, but has been observed to cause severe, even grave, illness in persons with pre-existing conditions. The pathogenesis of C. canimorsus is still largely unknown, but increased clinical diagnoses have fostered an interest in the bacillus. Treatment with antibiotics is effective in most cases, but the most important yet basic diagnostic tool available to clinicians remains the knowledge of recent exposure to canines or felines.
The class Flavobacteriia is composed of a single class of environmental bacteria. It contains the family Flavobacteriaceae, which is the largest family in the phylum Bacteroidota. This class is widely distributed in soil, fresh, and seawater habitats. The name is often spelt Flavobacteria, but was officially named Flavobacteriia in 2012.
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.
Chryseobacterium is a genus of Gram-negative bacteria. Chryseobacterium species are chemoorganotrophic, rod shape gram-negative bacteria. Chryseobacterium form typical yellow-orange color colonies due to flexirubin-type pigment. The genus contains more than 100 described species from diverse habitats, including freshwater sources, soil, marine fish, and human hosts.
Achromobacter xylosoxidans is a Gram-negative, aerobic, oxidase and catalase-positive, motile bacterium with peritrichous flagella, from the genus Achromobacter. It is generally found in wet environments. Achromobacter xylosoxidans can cause infections such as bacteremia, especially in patients with cystic fibrosis. In 2013, the complete genome of an A. xylosoxidans strain from a patient with cystic fibrosis was sequenced.
Chryseobacterium soli is a bacterium. It is aerobic, Gram-negative, non-motile, yellow-pigmented and straight rod-shaped. Its type strain is JS6-6(T).
Elizabethkingia anophelis is a yellow-pigmented, rod-shaped, gram-negative bacterium in the Flavobacteriaceae family. E. anophelis was first isolated from the midgut of Anopheles gambiae mosquitoes. It is one of several potentially pathogenic species in the genus Elizabethkingia and has been identified in the 2016 United States Elizabethkingia outbreak.
Elizabeth Osborne King was an American microbiologist who discovered and described bacteria of medical importance at the United States Centers for Disease Control and Prevention from the late 1940s through the early 1960s. A 1984 CDC manual dedication referred to King as "internationally known as an authority on a variety of unusual bacteria." The genera Kingella and Elizabethkingia and several species of bacteria are named to honor her for her pioneering work. King died of cancer on April 8, 1966, in Atlanta, where she is interred in Oakland Cemetery.
Elizabethkingia miricola is a species of bacterium isolated from condensation water in Space Station Mir, related to Elizabethkingia anophelis, the cause of the 2016 outbreak of Elizabethkingia anophelis human infections in Wisconsin that began in early November 2015. The genus name Elizabethkingia honors former United States Centers for Disease Control (CDC) microbiologist Elizabeth O. King, and the specific epithet is derived from combining the Russian name of the space station from which the bacterium was isolated, "Mir" meaning "peace," and the Latin "incola" meaning "inhabitant," yielding miricola, "inhabitant of the Mir space station."
Elizabethkingia is a genus of bacterium in the order of Flavobacteriales. It was established in 2005 from a branch in of the genus Chryseobacterium, and named after Elizabeth O. King, the discoverer of the type species. Elizabethkingia has been found in soil, rivers, and reservoirs worldwide. The genus contains several pathogenic species, such as E. meningoseptica and E. anophelis.
Chryseobacterium bernardetii is a bacterium from the genus Chryseobacterium.
Chryseobacterium contaminans is a Gram-negative and rod-shaped bacteria from the genus Chryseobacterium which has been isolated from a rhizosphere contamination from an agar plate in Alabama in the United States.
Chryseobacterium lactis is a Gram-negative bacteria from the genus Chryseobacterium.
Chryseobacterium taklimakanense is a Gram-negative and rod-shaped bacteria from the genus Chryseobacterium.
Chryseobacterium scophthalmum is a Gram-negative and rod-shaped bacteria from the genus Chryseobacterium which has been isolated from the gills of a turbot in Scotland. Chryseobacterium scophthalmum produces flexirubin.
Christensenella hongkongensis is a species of clinically relevant gram-positive coccobacilli, first isolated from patients in Hong Kong and Canada in 2006. Although the species remains relatively rare, it has a high mortality rate of up to 50%. Christensenella is thought to be broadly distributed globally, as it has been isolated from patient blood cultures around the world including Hong Kong, South Korea, New Zealand, Canada, Sweden, France and Italy. Fewer than 15 cases of C. hongkongensis have been observed worldwide.