THE SUSCEPTIBILITY TO ANTIBIOTICS OF SOME
STREPTOCOCCUS CONSTELLATUS STRAINS ISOLATED FROM
ODONTOGENIC INFECTIONS
GABRIELA BĂNCESCU#, CARMEN DEFTA#, ADRIAN BĂNCESCU#*, MIRCEA HÎRJĂU#
“Carol Davila” University of Medicine and Pharmacy, Bucharest, Romania
*corresponding author: adrianbancescu@yahoo.com
#All authors have equal contribution
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Abstract:
The aim of the present study was the investigation of the antimicrobial susceptibility of 45 isolates of Streptococcus
constellatus from different odontogenic infections. The E-test was applied for testing their susceptibility against the following
antibiotics: penicillin G, ampicillin, cefotaxime, erythromycin, clindamycin, tetracycline, levofloxacin, linezolid and
vancomycin. In addition, the double disk diffusion method was used for determining the erythromycin resistance phenotype.
The results indicated that all the strains were susceptible to: beta-lactam antibiotics, levofloxacin, linezolid and vancomycin,
while only 56% of them were susceptible to tetracycline. Six of the tested strains were resistant to erythromycin, showing the
M phenotype, except for one isolate which manifested inducible clindamycin resistance. In conclusion, penicillin remains the
therapeutic choice when S. constellatus is involved in infections requiring antimicrobial treatment, but in case of allergy to
beta-lactam antibiotics, macrolides and clindamycin should be chosen as alternatives only, according to the in vitro
susceptibility results.

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