Abiotrophia defectiva: Difference between revisions

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==Cell and colony structure==
==Cell and colony structure==


Known as a type of [http://pathology5.pathology.jhmi.edu/micro/v15n41.htm “nutritionally variant streptococci,”] ''A. defectiva'', when grown on blood agar, can grow in either non-hemolytic or alpha-hemolytic satelliting colonies and is usually supported by many gram-positive and gram-negative bacteria. Varying from typical gram-positive streptococci to gram-variable enlarged pleomorphic coccobacilli, the microscopic morphology of the organisms is medium dependent. <sup>1</sup>  
Known as a type of [http://pathology5.pathology.jhmi.edu/micro/v15n41.htm “nutritionally variant streptococci,”] ''A. defectiva'', when grown on blood agar, can grow in either [http://en.wikipedia.org/wiki/Hemolysis_(microbiology) non-hemolytic] or alpha-hemolytic satelliting colonies and is usually supported by many gram-positive and gram-negative bacteria. Varying from typical gram-positive streptococci to gram-variable enlarged pleomorphic coccobacilli, the microscopic morphology of the organisms is medium dependent. <sup>1</sup>  




==Metabolism==
==Metabolism==


''A. defectiva'' is classified as a Gram-positive, facultative aerobe. <sup>3</sup> ''A. defectiva'' is a fastidious organism that requires a complex media enriched with L-cysteine or vitamin B6 as well as other unique nutritional requirements that are essential for growth. <sup>4</sup> Since it grows slower than other streptococci, cultivation and identification can be difficult; thus, phenotypic identification can result in a misidentification of the pathogen. <sup>5</sup>
''A. defectiva'' is classified as a Gram-positive, facultative aerobe. <sup>3</sup> ''A. defectiva'' is a [http://www.biology-online.org/dictionary/Fastidious_organism fastidious] organism that requires a complex media enriched with L-cysteine or vitamin B6 as well as other unique nutritional requirements that are essential for growth. <sup>4</sup> Since it grows slower than other streptococci, cultivation and identification can be difficult; thus, phenotypic identification can result in a misidentification of the pathogen. <sup>5</sup>




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==Pathology==
==Pathology==


Because ''A. defectiva'' has been frequently found in dental plaque <sup>6</sup>, the oral cavity is often the portal of entry. <sup>5</sup> Although it is rare for ''A. defectiva'' to cause endocarditis, some studies estimate that it is responsible for 5-6% of all cases of inflammatory endocarditis and has a greater morbidity and mortality than endocarditis caused by other streptococci due to its poor response to many antibiotics. However, it is susceptible to and commonly treated with vancomycin. Complications such as congestive heart failure, embolization and an increased rate of surgical interventions often occur in conjunction with endocarditis caused by ''A. defectiva''. The production of exopolysaccharide is one of the factors that contributes to the increased virulence of ''Abiotrophia'' species due to its long generation time which can have an impact on ''in vivo'' tolerance; the development of cell-wall deficient bacteria results in persistence which is often promoted by treatment with β-lactam antibiotics. <sup>5</sup>
Because ''A. defectiva'' has been frequently found in dental plaque <sup>6</sup>, the oral cavity is often the portal of entry. <sup>5</sup> Although it is rare for ''A. defectiva'' to cause endocarditis, some studies estimate that it is responsible for 5-6% of all cases of inflammatory endocarditis and has a greater morbidity and mortality than endocarditis caused by other streptococci due to its poor response to many antibiotics. However, it is susceptible to and commonly treated with vancomycin. Complications such as congestive heart failure, embolization and an increased rate of surgical interventions often occur in conjunction with endocarditis caused by ''A. defectiva''. The production of exopolysaccharide is one of the factors that contributes to the increased virulence of ''Abiotrophia'' species due to its long generation time which can have an impact on ''in vivo'' tolerance; the development of cell-wall deficient bacteria results in persistence, which is often promoted by treatment with β-lactam antibiotics. <sup>5</sup>


==References==
==References==
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[http://www.ncbi.nlm.nih.gov/pubmed/15599782 (4)] Beljerd M, Bouvet A, Le Coustumier A, Loubinoux J, Sire S, Wilhelm N. First case of multiple discitis and sacroiliitis due to Abiotrophia defectiva. Eur J Clin Microbiol Infect Dis. 2005; 24: 76–78. [doi: 10.1007/s10096-004-1265-7].
[http://www.ncbi.nlm.nih.gov/pubmed/15599782 (4)] Beljerd M, Bouvet A, Le Coustumier A, Loubinoux J, Sire S, Wilhelm N. First case of multiple discitis and sacroiliitis due to Abiotrophia defectiva. Eur J Clin Microbiol Infect Dis. 2005; 24: 76–78. [doi: 10.1007/s10096-004-1265-7].


[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3078235/?tool=pubmed (5)] Asma A, Mohammed A, Mushira E. Endocarditis caused by Abiotrophia defectiva. Libyan J Med. 2007; 2(1): 43–45. [doi: 10.4176/061223].
[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3078235/?tool=pubmed (5)] Asma A, Mohammed A, Mushira E. Endocarditis caused by ''Abiotrophia defectiva''. Libyan J Med. 2007; 2(1): 43–45. [doi: 10.4176/061223].




Edited by Kim Derby of Dr. Lisa R. Moore, University of Southern Maine, Department of Biological Sciences, http://www.usm.maine.edu/bio
Edited by Kim Derby of Dr. Lisa R. Moore, University of Southern Maine, Department of Biological Sciences, http://www.usm.maine.edu/bio

Revision as of 02:49, 4 May 2012

This student page has not been curated.

A Microbial Biorealm page on the genus Abiotrophia defectiva

Hemoculture of Abiotrophia defectiva [[1]]

Classification

Higher order taxa

Bacteria; Firmicutes; Bacilli; Lactobacillales; Aerococcaceae; Abiotrophia

Species

Abiotrophia defectiva

NCBI: Taxonomy


Description and significance

Gram-positive culture of Abiotrophia defectiva [[2]]

Most often growing in small, satellite colonies around colonies of associated bacterial species, Abiotrophia defectiva has been shown to reside in the oral and upper respiratory flora as well as in the intestinal mucosa; it can cause bacterial, infectious endocarditis, bacteremia, and some cases of culture-negative endocarditis. 1

Genome structure

NCBI: Genome

According to the NCBI database, A. defectiva is shown to have 3291 protein sequences encoded in a 3.4792 Mbp genome with a GC content of 37.0% 2.


Cell and colony structure

Known as a type of “nutritionally variant streptococci,” A. defectiva, when grown on blood agar, can grow in either non-hemolytic or alpha-hemolytic satelliting colonies and is usually supported by many gram-positive and gram-negative bacteria. Varying from typical gram-positive streptococci to gram-variable enlarged pleomorphic coccobacilli, the microscopic morphology of the organisms is medium dependent. 1


Metabolism

A. defectiva is classified as a Gram-positive, facultative aerobe. 3 A. defectiva is a fastidious organism that requires a complex media enriched with L-cysteine or vitamin B6 as well as other unique nutritional requirements that are essential for growth. 4 Since it grows slower than other streptococci, cultivation and identification can be difficult; thus, phenotypic identification can result in a misidentification of the pathogen. 5


Ecology

PCR amplification is often used to identify A. defectiva by analyzing the 16S rDNA genes and comparing the sequence to the NCBI data bank 1.

Pathology

Because A. defectiva has been frequently found in dental plaque 6, the oral cavity is often the portal of entry. 5 Although it is rare for A. defectiva to cause endocarditis, some studies estimate that it is responsible for 5-6% of all cases of inflammatory endocarditis and has a greater morbidity and mortality than endocarditis caused by other streptococci due to its poor response to many antibiotics. However, it is susceptible to and commonly treated with vancomycin. Complications such as congestive heart failure, embolization and an increased rate of surgical interventions often occur in conjunction with endocarditis caused by A. defectiva. The production of exopolysaccharide is one of the factors that contributes to the increased virulence of Abiotrophia species due to its long generation time which can have an impact on in vivo tolerance; the development of cell-wall deficient bacteria results in persistence, which is often promoted by treatment with β-lactam antibiotics. 5

References

(1)Hughs J, Jackson B, Kintner K, Namdari H, Namdari S, Peairs R, Savage D. Abiotrophia Species as a Cause of Endophthalmitis Following Cataract Extraction. J Clin Microbiol. 1999 May; 37(5): 1564–1566.

(2) http://www.ncbi.nlm.nih.gov/genome/?term=abiotrophia%20defectiva

(3) Embil J. and Vinh D (2006). Treatment of Native Valve Endocarditis: General Principles and Therapy for Specific Organisms. In K Chan & J Embil (Eds). Endocarditis: Diagnosis and Management (pp. 121-183) [doi: 10.1007/978-1-84628-453-3_9].

(4) Beljerd M, Bouvet A, Le Coustumier A, Loubinoux J, Sire S, Wilhelm N. First case of multiple discitis and sacroiliitis due to Abiotrophia defectiva. Eur J Clin Microbiol Infect Dis. 2005; 24: 76–78. [doi: 10.1007/s10096-004-1265-7].

(5) Asma A, Mohammed A, Mushira E. Endocarditis caused by Abiotrophia defectiva. Libyan J Med. 2007; 2(1): 43–45. [doi: 10.4176/061223].


Edited by Kim Derby of Dr. Lisa R. Moore, University of Southern Maine, Department of Biological Sciences, http://www.usm.maine.edu/bio