Lactobacillus species associated with active caries lesions.

Lactobacilli that are most frequently associated with active caries lesions in dentine were isolated and identified as part of a research project which aims to determine the role of the predominant species of these organisms in the carious process. Samples of carious dentine were collected from 12 patients with open caries lesions (Group A) and stimulated saliva samples were collected from 12 patients with a DMFT = 0 and confirmed presence of lactobacilli in the oral cavity (Group B). After serial dilutions samples were plated on Rogosa agar and incubated anaerobically at 37 degrees C for 48 hours. Representative colonies were isolated from each sample, using Harrison's disc and species were identified by classical taxonomy. A total of 153 isolates were identified. The redefinition and description of lactobacilli species in recent systematic literature resulted in a new and different species composition of oral lactobacilli as shown in this study, namely: homofermentative species (Group A = 82 per cent; Group B = 90 per cent) were predominantly Lactobacillus paracasei (Group A = 39 per cent; Group B = 30 percent) and Lactobacillus rhamnosus (Group A = 31 per cent; Group B = 41 per cent). Heterofermentative species (Group A = 18 per cent; Group B = 10 per cent) were predominantly Lactobacillus fermentum (Group A = 68 per cent; Group B = 100 percent).

Oral yeast flora of a Kalahari population.

During an epidemiological survey of 181 individuals working or residing in the Kalahari National Gemsbok Park, swabs were taken from the dorsal surfaces of their tongues to determine a possible association between oral yeasts and clinically observed oral lesions as well as other underlying conditions detectable by serum chemistry. Identification of yeasts was performed with a commercially available identification system, namely the ATB 32C (Montalieu, Vercieu). Yeasts were isolated from 30.4 per cent (n = 55) of individuals, of whom 43.6 per cent (n = 24) had only Candida albicans, 3.6 per cent (n = 2) had C. albicans together with other yeasts and 52.7 per cent (n = 29) had other yeasts. Many of these yeasts were not the commonly encountered clinical isolates. The results revealed a significant association (p < 0.02) between yeasts (n = 55) and low serum iron concentrations (n = 50). A highly significant (p < 0.001) association was also found between smoking (n = 112) and the presence of clinically detectable oral lesions, notably leukoplakia (n = 21) and mucosal atrophy. The findings of this study reveal that a significant association exists between the oral yeast flora and serum iron and glucose, as well as between smoking and oral mucosal lesions.

Anaerobic bacteria in orofacial abscesses.

Obligate anaerobic bacteria were cultured from 15 orofacial abscesses. Bacteroides species constituted 43 per cent, Clostridium 21 per cent, Fusobacterium 14 per cent, Peptostreptococci 11 per cent, peptococci 7 per cent and Veillonella 4 per cent of the isolates. This study confirms the polymicrobial nature of orofacial infections. Sensitivity to antibiotics was unpredictable. Clostridium difficile, Clostridium tetani, Peptostreptococcus productus and Veillonella parvula showed resistance to some of the most frequently used antibiotics. Ampicillin and tetracycline were the most effective antibiotics and the highest resistance was shown against erythromycin.