The Effect of pH on the Sensitivity of Species of Lactobacillus to Chlorhexidine and the Antibiotics Minocycline and Spiramycin

Abstract

The purpose of this study was to determine the sensitivity of a range of Lactobacillus species to chlorhexidine, Minocycline, and Spiramycin, at a range of pH from 5.0 to 7.4. Strains of Streptococcus were also tested for their sensitivity to chlorhexidine, as a comparison between the genera. There were both inter- and intra-species variations in the sensitivity of these strains to chlorhexidine. The strains tested were sensitive at pH 6. 7 to the following levels of chlorhexidine (μg/mL) : L. casei (6 strains), 10-60; L. plantarum (4 strains), 40; L. fermentum (13 strains), 2-20; L. brevis (1 strain), 10; and L. acidophilus (3 strains), 10-60. The Streptococcus species were sensitive to 1-4 μ/mL (13 strains); 4-10 μg/mL (3 strains); and 10-20 μg/mL (2 strains). One strain was able to survive 20 μg/mL. Chlorhexidine was found to be less effective at lower pH levels. The following examples show sensitivity (μg/mL) at pH 6.5 followed by sensitivity at pH 5.0 : L. casei (ATCC 15008), 40,60 ; L. plantarum (CH 374), 40,100 ; L. fermentum (CH 324) 10,40 ; L. acidophilus (ATCC 4356), 10,40 ; and S. mutans (BM 52), 2,2.

All of the strains of Lactobacillus tested with Spiramycin were resistant at pH 5.0. Minocycline was less affected by changes in pH, but at pH 7.4 Lactobacillus strains were more resistant to Minocycline as compared with Spiramycin. Both of these antibiotics are bacteriostatic, and therefore may have a more limited effect than a bactericidal agent such as chlorhexidine.

The Lactobacillus strains tested required higher concentrations of chlorhexidine than did the strains of Streptococcus for a killing effect in vitro.

Get full access to this article

View all access options for this article.

References

Baker, P.J. ; Evans, R.T. ; Slots, J. ; and Genco, R.J. (1985): Antibiotic Sensitivity of Anaerobic Bacteria from the Human Oral Cavity, J Dent Res 64:1233-1244.

Balanyk, T.E. and Sandham, H.J. (1985): Development of Sustained-release Antimicrobial Dental Varnishes Effective against Streptococcus mutans in vitro, J Dent Res 64:1356-1360.

Bowden, G.H. ; Milnes, A.R. ; and Boyar, R.M. (1984): Streptococcus mutans and Caries: State of the Art. In: Cariology Today , B. Guggenheim , Ed., Basel: Karger, pp. 173-181.

Boyar, R.M. and Bowden, G.H. (1985): The Microflora Associated with the Progression of Incipient Carious Lesions in Teeth of Children Living in a Water Fluoridated Area, Caries Res 19 :289-297.

Burt, B.A. ; Loesche, W.J. ; and Eklund, S.A. (1985): Stability of Selected Plaque Species and their Relationship to Caries in a Child Population over Two Years, Caries Res 19:193-200.

Coykendall, A.L. and Gustafson, K.B. (1986): Taxonomy of Streptococcus mutans. In: Molecular Microbiology and Immunobiology of Streptococcus mutans, H. Hamada , S.M. Michalek , H. Konovo , L. Menaker , and J.R. McGhee , Eds., Amsterdam: Elsevier, pp. 21-28.

De Man, J.C. ; Rogosa, M. ; and Sharpe, M.E. ( 1960): A Medium for the Cultivation of Lactobacilli, J Appl Bact 233 :130-134.

Dirksen, T.R. ; Little, M.F. ; Bibby, B.G. ; and Crump, S.L. ( 1962): The pH of Carious Cavities. I. Effect of Glucose and Phosphate Buffer on Cavity pH, Arch Oral Biol 7:49-58.

Emilson, C.G. ( 1977): Susceptibility of Various Microorganisms to Chlorhexidine , Scand J Dent Res 85:255-265.

10.

Emilson, C.G. ( 1981): Effect of Chlorhexidine Gel Treatment on Streptococcus mutans Populations in Human Saliva and Dental Plaque, Scand J Dent Res 89:239-246.

11.

Emilson, C.G. ; Lindquist, B. ; and Wennerholm, K. (1987): Recolonization of Human Tooth Surfaces by Streptococcus mutans after Suppression by Chlorhexidine Treatments, J Dent Res 66 :1503-1508.

12.

Gusberti, F.A. ; Sampathkumar, P. ; Siegrist, B.E. ; and Lang, N.P. (1988): Microbiological and Clinical Effects of Chlorhexidine Digluconate and Hydrogen Peroxide Mouthrinses on Developing Plaque and Gingivitis , J Clin Periodontol 15 :60-67.

13.

Hamada, S. and Slade, H.D. (1980): Biology, Immunology and Cariogenicity of Streptococcus mutans, Microbiol Rev 44 :331-384.

14.

Hardie, J.M. ; Thomson, P.L. ; South, R.J. ; Marsh, P.D. ; Bowden, G.H. ; McKee, A.S. ; Fillery, E.D. ; and Slack, G.L. ( 1977): A Longitudinal Epidemiological Study on Dental Plaque and the Development of Dental Caries: Interim Results after Two Years, J Dent Res 56:90C-98C.

15.

Kristofferson, K. and Bratthall, D. ( 1982): Transient Reduction of Streptococcus mutans Interdentally by Chlorhexidine Gel, Scand J Dent Res 90:417-422.

16.

Lennette, E.H. ; Ballows, A. ; Hausler, W.J. ; and Truant, J.P. ( 1980): Manual of Clinical Microbiology, 3rd ed., Washington, D.C.: American Society for Microbiology, pp. 446-474.

17.

Löe, H. ; Schiøtt, C.R. ; Glavind, L. ; and Karring, T. ( 1976): Two Years Oral Use of Chlorhexidine in Man. 1. General Design and Clinical Effects, J Periodont Res 11:135-144.

18.

Loesche, W.J. ( 1976): Chemotherapy of Dental Plaque Infections, Oral Sci Rev 9:65-107.

19.

Loesche, W.J. and Straffon, L.H. ( 1979): Longitudinal Investigation of the Role of Streptococcus mutans in Human Fissure Decay, Infect Immun 26:498-507.

20.

Lundstrom, F. and Krasse, B. ( 1987): Streptococcus mutans and Lactobacilli Frequency in Orthodontic Patients; the Effect of Chlorhexidine Treatments, EurJ Orthod 9:109-116.

21.

Maltz-Turkienicz, M. ; Krasse, B. ; and Emilson, C.G. (1980): Effects of Chlorhexidine and Iodine on in vitro Plaques of Streptococcus mutans and Streptococcus sanguis, Scand J Dent Res 88:28-33.

22.

Milnes, A.R. and Bowden, G.H. ( 1985): The Microflora Associated with Developing Lesions of Nursing Caries, Caries Res 19:289-297.

23.

Ripa, L.W. ( 1978): Nursing Habits and Dental Decay in Infants: "Nursing Bottle Caries", J Dent Child 45:274-275.

24.

Schaeken, M.J.M. ; de Jong, M.H. ; Franken, H.C.M. ; and van der Hoeven, J.S. (1984): Effect of Chlorhexidine and Iodine on the Composition of the Human Dental Plaque Flora, Caries Res 18:401-407.

25.

Schaeken, M.J.M. ; de Jong, M.H. ; Franken, H.C.M. ; and van der Hoeven, J.S. (1986): Effects of Highly Concentrated Stannous Fluoride and Chlorhexidine Regimes on Human Dental Plaque Flora, J Dent Res 65:57-61.

26.

Stalons, D.R. and Thornsberry, C. ( 1975): Broth Dilution for Determining the Antibiotic Sensitivity of Anaerobic Bacteria, Antimicrob Agents Chemother 7:15-21.

27.

Steers, E. ; Foltz, E.L. ; Graves, B.S. ; and Riden, J. ( 1959): An Inocula Replicating Apparatus for Routine Testing of Bacterial Susceptibility to Antibiotics, Antibiot Chemother 9:307-311.

28.

Zickert, I. ; Emilson, C.G. ; and Krasse, B. ( 1982): Effect of Caries Preventative Measures in Children Highly Infected with the Bacterium Streptococcus mutans, Arch Oral Biol 27:861-868.