Abstract
Background: Lactobacillus are acid-producing bacteria associated with caries development. Some Lactobacillus have also anti-microbial properties. In patients treated for cancer in the head and neck region, a marked increase in Lactobacillus has previously been reported. The consequences of this ecological shift towards a Lactobacillus friendly environment are, however, still unknown. Little is known about the prevalence of different Lactobacillus species and their characteristics in these patients.
The aim of this study was therefore to identify Lactobacillus isolates from patients with head and neck cancer and to determine their acid-producing capacity and anti-microbial activity.
Methods: Lactobacillus isolates were collected from 21 patients pre-treatment, six and 12 months post treatment. For identification to species level, the isolates were subjected to DNA-extraction, amplification of 16S and restriction fragment length polymorphism analysis using the restriction enzymes Hpa II and Hae III. The acid-producing capacity was analyzed using a colorimetric fermentation test in microtiter plates. The anti-microbial activity of the isolates against Streptococcus mutans associated with caries, and the mucosal pathogens Staphylococcus aureus, Candida albicans and Enterococcus faecalis was determined by determining inhibitory zones on agar plates.
Results: The most frequent species were L. paracasei (n=21), L. casei/rhamnosus (n=17) and L. fermentum (n=10). The highest proportion showing acid-producing capacity using sugars and sugar-alcohols was found among L. paracasei and the lowest proportions were seen for L. fermentum. Seventy-one strains showed an anti-microbial activity against S. mutans, one strain against S. aureus and none against C. albicans or E. faecalis.
Conclusion: The most frequent species Lactobacillus species isolated from patients with head and neck cancer were L. paracasei, L. casei/rhamnosus and L. fermentum of which L. paracasei showed the best acid-producing capacity. A weak anti-microbial activity against S. mutans was frequently detected. Further studies are needed to increase the knowledge of the role and characteristics of oral Lactobacillus.
Explorative study on
Lactobacillus
species and their acid‐producing capacity and anti‐microbial activity in head and neck cancer patients
