The research thrust of our laboratory involves three areas of interest. The first area concerns the delineation of the natural history of oral bacteria responsible for dental caries, including genetic and environmental events that influence the acquisition and transmission of bacteria indigenous to humans. More specifically, our present focus is in three areas: 1) windows of infectivity for acquisition of indigenous bacteria, 2) fidelity of genotypic transmission and 3) clonality of caries-associated strains of Streptococcus mutans. We are looking at what biological rules govern the opening and closing of this window in infants; infants who do not become infected with S. mutans during this window may remain free of these organisms and do not manifest disease, i.e., caries. The recent development of a DNA fingerprinting techniques allows us to study transmission /acquisition as well as describe polymorphic behavior inherent to indigenous bacteria that are vertically transmitted. The conservation of S. mutans within both racial and familial lines suggests a pattern of co-evolution between host and parasite. Because S. mutans is transmitted vertically, i.e., mother to child, clonal types are confined within racial and familial cohorts. If clonality proves to be true for all strains of S. mutans, then virulence factors can be traced based on commonality of certain clones among children with severe caries. It follows that diagnostic tools can then be developed capable of predicting risk before the initiation of caries.
Our second major interest is developing techniques for characterizing diversity of bacteria within plaque biofilms associated with dental caries. To do this, we have developed two systems of DNA profiling – one using gradient gels (DGGE) to separate distinct 16S rDNA moieties representing individual species of bacteria from biofilm and the second subtraction DNA hybridization of genetic fragments. Both approaches are culture-independent, hence we should be able to expand our knowledge of the cariogenic biota to include the non-cultivable, and majority portion of the dental biofilm. These studies give us clues as to why some strains are more virulent than others.
Our third area of research is in the population structure of Streptococcus mutans and its co-evolution with its human host. Comparing phylogenies of different strains with and without plasmids reveal separate evolutionary pathways between plasmid and chromosomal frames. As humans migrated out of Africa, they carried their intraoral commensal biota, including S. mutans. These migrations parallel S. mutans phylogeny.
Caufield PW, Saxena D, Fitch D, Li Y. 2007, Population structure of plasmid-containing strains of Streptococcus mutans, a member of the human indigenous biota. J Bacteriol. 189(4):1238-43.
Caufield PW, Li Y, Dasanayake A, Saxena D. 2007. Diversity of lactobacilli in the oral cavities of young women with dental caries. Caries Res.;41(1):2-8.
Li Y, Ge Y, Saxena D, Caufield PW. 2007. Genetic profiling of the oral microbiota associated with severe early-childhood caries. J Clin Microbiol. 45(1):81-7
Caufield, P W, Li, Y and Saxena, D. 2006. Diversity of lactobacilli in the oral cavities of young women with .
Li, Y, Caufield, PW, Dasanayake, AP, Wiener, HW and Vermund, S. 2005. Mode of delivery and other maternal factors influence the acquisition of Streptococcus mutans in infants. J Dent. Res. 84:806-811.
Saxena D, Y. Li, and PW Caufield. 2005. Identification of unique bacterial gene segments from Streptococcus mutans with potential relevance to dental caries by subtraction DNA. hybridization. J Clin Microbiol, 43: 3508–3511.
Caufield, P W. 2005. Dental caries: an infectious and transmissible disease: where have we been and where are we going? NY State Dent J. 71:23-27.
Caufield, PW, Li Y, Dasanayake AP. 2005. Dental caries: an infectious and transmissible disease. Compendium, 26:10-16 (supplement).
Li Y, Ku C, Xu J, Saxena D and Caufield PW. 2005. Survey of oral microbial diversity using PCR-based denaturing gel electrophoresis. J Dent Res 84:559-565.
Li Y, Dasanayake AP, Caufield PW, Elliott RR, Butts, JT. 2003. Characterization of maternal mutans streptococci transmission in an African-American population. Dent Clinics North Am. 47:87-101.
Li Y, Pan Y, Qi F, Caufield PW. 2003. Identification of Streptococcus sanguinis using a PCR-based species-specific DNA probe. J Clin Microbiol. 41:3481-6.
Ruby JD, Li Y, Luo Y, Caufield PW. 2003. Genetic diversity of Actinomyces naeslundii genospecies 2 in mother-child pairs. Arch. Oral Biol. 48: 851-5.
Dasanayake AP, Wiener HW, Li Y, Vermund SV, Caufield, P.W. 2002. Lack of effect of chlorhexidine varnish on Streptococcus mutans transmission and caries in mothers and children. Caries Res 36 (4): 288-293.
Ruby J. D., Li, Y., Luo Y, Caufield, P.W. 2002. Genetic characterization of the oral Actinomyces. Arch. Oral Biol. 47 (6): 457-463.
Chen, P., F. Qi, J. Novak, R. E. Krull, and P. W. Caufield. 2001. Effect of amino acid substitutions in conserved residues in the leader peptide on biosynthesis of the lantibiotic mutacin II. FEMS Microbiol Lett 195:139-44.
Qi, F., P. Chen, and P. W. Caufield. 2001. The group I strain of Streptococcus mutans, UA140, produces both the lantibiotic mutacin I and a nonlantibiotic bacteriocin, mutacin IV. Appl Environ Microbiol 67:15-21.
Caufield, P. W., A. P. Dasanayake, and Y. Li. 2001. The antimicrobial approach to caries management. J Dent Educ 65:1091-5.
Mattos-Graner, R. O., Y. Li, P. W. Caufield, M. Duncan, and D. J. Smith. 2001. Genotypic diversity of mutans streptococci in Brazilian nursery children suggests horizontal transmission. J Clin Microbiol 39:2313-6.
Pan, Y. P., Y. Li, and P. W. Caufield. 2001. Phenotypic and genotypic diversity of Streptococcus sanguis in infants. Oral Microbiol Immunol 16:235-42.
Zhou, X., P. W. Caufield, Y. Li, and F. Qi. 2001. Complete nucleotide sequence and characterization of pUA140, a cryptic plasmid from Streptococcus mutans. Plasmid. 46:77-85.
Caufield, P. W., and A. L. Griffen. 2000. Dental caries. An infectious and transmissible disease. Pediatr Clin North Am 47:1001-19, v.
Caufield, P. W., A. P. Dasanayake, Y. Li, Y. Pan, J. Hsu, and J. M. Hardin. 2000. Natural history of Streptococcus sanguinis in the oral cavity of infants: evidence for a discrete window of infectivity. Infect Immun 68:4018-23.
Krull, R. E., P. Chen, J. Novak, M. Kirk, S. Barnes, J. Baker, N. R. Krishna, and P. W. Caufield. 2000. Biochemical structural analysis of the lantibiotic mutacin II. J Biol Chem 275:15845-50.
Li, Y., W. Wang, and P. W. Caufield. 2000. The fidelity of mutans streptococci transmission and caries status correlate with breast-feeding experience among Chinese families. Caries Res 34:123-32.
Qi, F., P. Chen, and P. W. Caufield. 2000. Purification and biochemical characterization of mutacin I from the group I strain of Streptococcus mutans, CH43, and genetic analysis of mutacin I biosynthesis genes. Appl Environ Microbiol 66:3221-9.
Acton, R. T., A. P. Dasanayake, R. A. Harrison, Y. Li, J. M. Roseman, R. C. Go, H. Wiener, and P. W. Caufield. 1999. Associations of MHC genes with levels of caries-inducing organisms and caries severity in African-American women. Hum Immunol 60:984-9.
Chen, P., F. Qi, J. Novak, and P. W. Caufield. 1999. The specific genes for lantibiotic mutacin II biosynthesis in Streptococcus mutans T8 are clustered and can be transferred en bloc. Appl Environ Microbiol 65:1356-60.
Qi, F., P. Chen, and P. W. Caufield. 1999. Purification of mutacin III from group III Streptococcus mutans UA787 and genetic analyses of mutacin III biosynthesis genes. Appl Environ Microbiol 65:3880-7.
Qi, F., P. Chen, and P. W. Caufield. 1999. Functional analyses of the promoters in the lantibiotic mutacin II biosynthetic locus in Streptococcus mutans. Appl Environ Microbiol 65:652-8.
