Oral Biol Res.  2020 Mar;44(1):1-7. 10.21851/obr.44.01.202003.1.

Effects of antibiotics at sub-minimal inhibitory concentrations on the morphology of Streptococcus mutans and Lactobacillus acidophilus

• Kwon YW
• Lee SY

• KMID: 2504269
• DOI: http://doi.org/10.21851/obr.44.01.202003.1

Abstract

Sub-minimal inhibitory concentrations (sub-MICs) of antibiotics may have significant impact on the morphology and biochemical characteristics of target bacteria. This study aimed to examine the morphological changes to sub-MICs of antibiotics observed in bacterial cells from Gram-positive oral species, Streptococcus mutans and Lactobacillus acidophilus. The MICs for both amoxicillin and doxycycline were determined by broth dilution method. Individual cells of S. mutans increased in length after incubation with sub-MIC of amoxicillin, whereas its chain length increased in response to a sub-MIC of doxycycline. The lengths of individual bacterial cells of L. acidophilus decreased after incubation with sub-MICs of either amoxicillin or doxycycline. These results of suggest that subMICs of amoxicillin and doxycycline induce morphological changes in both S. mutans and L. acidophilus. Further studies are required to determine the significance of these findings for host–pathogen interactions and development of dental diseases.

Keyword

Lactobacillus acidophilus; Morphology; Streptococcus mutans; Sub-minimal inhibitory concentration