Oral Lactobacillus species in type 2 diabetic patients living in southern Thailand

Although lactobacilli are part of normal oral, gastrointestinal and genitourinary flora, they are an uncommon cause of infections in human. Lactobacillus-associated infections have generally occurred in patients with serious underlying conditions e.g. diabetes and cancer that might favour certain microorganisms. The aim of this study was to characterize species and genotypes of lactobacilli isolated from diabetic patients and non-diabetic subjects. One hundred and five type 2 diabetic patients and 103 non-diabetic subjects were recruited in this study. A total of 170 isolates of Lactobacillus were identified using 16S rRNA gene PCR-RFLP and genotyping were performed using AP-PCR by ERIC primers. It was found that type 2 diabetic patients had a significantly higher prevalence (p = 0.008) and level of lactobacilli than non-diabetic controls (p = 0.030). The most frequently isolated Lactobacillus spp. were L. casei/paracasei and L. fermentum in both the diabetic and non-diabetic groups. Strains of L. casei/paracasei and L. fermentum from between and within individuals were genotyped, and the genotyping of Lactobacillus strains showed diversity between individuals. One up to three genotypes of these two species could be found in the same subject. Interestingly, fewer genotypes were found in the diabetic patients than in the non-diabetic subjects.