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Enterococcus
From Wikipedia, the free encyclopedia
| Enterococcus | ||||||||||||
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 Enterococcus sp. infection in pulmonary tissue.
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E. avium |
Enterococcus is a genus of lactic acid bacteria of the phylum Firmicutes. Members of this genus were classified as Group D Streptococcus until 1984 when genomic DNA analysis indicated that a separate genus classification was appropriate.[1]
Enterococci are Gram-positive cocci which often occur in pairs (diplococci) and are difficult to distinguish from Streptococci on physical characteristics alone. Two species are common commensal organisms in the intestines of humans: E. faecalis (90-95%) and E. faecium (5-10%). Enterococci are facultative anaerobic organisms, i.e. they prefer the use of oxygen, but they can survive in the absence of oxygen.[2] They typically exhibit gamma-hemolysis on sheep's blood agar.
Important clinical infections caused by Enterococcus include urinary tract infections, bacteremia, bacterial endocarditis, diverticulitis, and meningitis.[3] Sensitive strains of these bacteria can be treated with ampicillin and vancomycin.[4]
From a medical standpoint, the most important feature of this genus is their high level of endemic antibiotic resistance. Some Enterococci are intrinsically resistant to β-lactam-based antibiotics (some penicillins and virtually all cephalosporins) as well as many aminoglycosides.[3] In the last two decades, particularly virulent strains of Enterococcus which are resistant to vancomycin (Vancomycin-Resistant Enterococcus, or VRE) have emerged in nosocomial infections of hospitalized patients especially in the US. Other developed countries such as the UK have been spared this epidemic, and in 2005, Singapore managed to halt an epidemic of VRE. VRE may be treated with Quinupristin/dalfopristin (Synercid) with response rates of approximately 70%.[5]
Enterococcal meningitis is a rare complication of neurosurgery. It often requires treatment with intravenous vancomycin; intrathecal vancomycin is often used and it is debatable whether this has any impact on outcome. The removal of any neurological devices is a crucial part of the management of these infections.[6]
In bodies of water, the acceptable level of contamination is very low, for example in the state of Hawaii, with among the strictest tolerances in the United States, the limit for water off its beaches is 7 colony forming units per 100 ml of water, above which the state may post warnings to stay out of the ocean.[7] In 2004, Enterococcus spp. took the place of fecal coliform as the new federal standard for water quality at public beaches. It is believed to provide a higher correlation than fecal coliform with many of the human pathogens often found in sewage.[8]
- ^ Schleifer KH; Kilpper-Balz R (1984). "Transfer of Streptococcus faecalis and Streptococcus faecium to the genus Enterococcus nom. rev. as Enterococcus faecalis comb. nov. and Enterococcus faecium comb. nov.". Int. J. Sys. Bacteriol. 34: 31–34.
- ^ Fischetti VA; Novick RP; Ferretti JJ; Portnoy DA; Rood JI (editors) (2000). Gram-Positive Pathogens. ASM Press. ISBN 1-55581-166-3.
- ^ a b Ryan KJ, Ray CG (editors) (2004). Sherris Medical Microbiology, 4th ed., McGraw Hill, 294–5. ISBN 0-8385-8529-9.
- ^ Pelletier LL Jr. (1996). Microbiology of the Circulatory System. in: Baron's Medical Microbiology (Baron S et al, eds.), 4th ed., Univ of Texas Medical Branch. ISBN 0-9631172-1-1.
- ^ Tünger A, Aydemir S, Uluer S, Cilli F (2004). "In vitro activity of linezolid & quinupristin/dalfopristin against Gram-positive cocci". Indian J Med Res 120 (6): 546-52. PMID 15654141.
- ^ Guardado R, Asensi V, Torres JM, et al (2006). "Post-surgical enterococcal meningitis: clinical and epidemiological study of 20 cases". Scand. J. Infect. Dis. 38 (8): 584-8. doi:10.1080/00365540600606416. PMID 16857599.
- ^ Clean Water Branch. Hawaii State Department of Health. Retrieved on 2007-02-08.
- ^ Jin G, Jeng HW, Bradford H, Englande AJ (2004). "Comparison of E. coli, enterococci, and fecal coliform as indicators for brackish water quality assessment". Water Environ. Res. 76 (3): 245-55. PMID 15338696.