**14. Rifampin**

Rifampin appears to be one of the most effective antibiotics against NVS although the data is limited. It was shown that Rifampin had a minimal bactericidal concentration of 2 μg/ml while that of penicillin was 1 μg/ml [60]. Combination of Vancomycin and Rifampin showed synergy in in vitro studies [74]. According to one review of 15 isolates of *Abiotrophia* and *Granulicatella* species, all isolates were found to be susceptible to Rifampin with MICs ≤0.012 μg/ml [64].

lack of large clinical studies and our knowledge about these organisms is based on relatively

Endocarditis Caused by *Abiotrophia* and *Granulicatella* Species

http://dx.doi.org/10.5772/intechopen.74252

53

Differences in pathogenicity and susceptibility to antimicrobials have been demonstrated among these heterogeneous group of bacteria. More studies are needed to determine if there are further species specific differences of these fascinating microorganisms which would help us improve our understanding, diagnosis and the treatment outcomes of infections caused

Department of Internal Medicine, Mercy Philadelphia Hospital, Drexel University College of

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[2] Ruoff KL. Nutritionally variant streptococci. Clinical Microbiology Reviews. 1991;**4**(2):

[3] Heather M, Rhodes DH, Lubna Shabnam DN. Williams and Glen T. Hansen, infective endocarditis due to *Abiotrophia* defectiva and *Granulicatella* spp. complicated by infectious intracranial cerebral aneurysms: A report of three cases and review of the litera-

[4] Roberts RB, Krieger AG, Schiller NL, Gross KC. Viridans streptococcal endocarditis: The role of various species, including Pyridoxal-dependent streptococci. Reviews of

[5] Okada Y et al. Endocardiac infectivity and binding to extracellular matrix proteins of oral *Abiotrophia* species. FEMS Immunology and Medical Microbiology. 2000;**27**(3):257-261 [6] Horstkotte MA et al. *Abiotrophia* defectiva endophthalmitis with retinal involvement and infiltrative keratitis: Case report and review of the literature. European Journal of

[7] da Silva Curiel JM et al. Nutritionally variant streptococci associated with corneal ulcers in horses: 35 cases (1982-1988). Journal of the American Veterinary Medical Association.

small number of reported cases.

Medicine, Philadelphia, PA, USA

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Gul Madison, Reshma Golamari and Priyanka Bhattacharya\*

\*Address all correspondence to: pbhattacharya@mercyhealth.org

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by NVS.

**Author details**

**References**
