The Persistence of <i>Streptococcus mutans</i> in Nasopharyngeal Carcinoma Patients after Radiotherapy

Abstract

The aim of the study was to examine the persistence of oral Streptococcus mutans in nasopharyngeal carcinoma patients after radiotherapy. Ten subjects, ranging in age from 20 to 67 years, participated. DMFT/DMFS, salivary level of mutans streptococci and oral health status were recorded. Pooled plaque samples were obtained from the cervical margins and the interproximal regions of all the teeth and the occlusal surfaces of the molars prior to, immediately after, 3 and 6 months after the completion of radiotherapy. At least 10 colonies of S. mutans were isolated from each subject and totally 645 isolates were genotyped by restriction endonuclease analysis. The results showed that the salivary level of S. mutans increased significantly with the reduction of salivary flow rate after radiotherapy. Each subject had at least 1 genotype of S. mutans isolated throughout the follow-up period. In 3 subjects who initially carried 2 or more genotypes, 1 or 2 genotypes of S. mutans could not be detected 3 months after treatment. Moreover, the genotypes that became undetectable were predominant bacteria in the first sampling. The result indicated that most S. mutans genotypes were persistent after radiotherapy but some genotypes that might not adapt to the alteration of oral environment became undetectable.

Hyperbaric oxygen treatment for the management of radiation‐induced xerostomia

“…The consequence to reduced saliva is plaque formation and disruption to the normal oral bioflora species. Cariogenic species such as Streptococcus mutans and Lactobacillus proliferate with consequential need for tooth extraction and the resultant risk of failure to heal and possible ORN …”

Does hyperbaric oxygen therapy have the potential to improve salivary gland function in irradiated head and neck cancer patients?

“…Following radiotherapy, patients have been shown to prefer soft and carbohydrate-rich foods [20]. With decreased salivary flow rate, oral clearance of sugar is prolonged, which can amplify the rapid progression of radiation caries [15].…”

“…These bacteria metabolize sugars to produce acids capable of dissolving tooth enamel, which eventually becomes cavitated. S. mutans is thought to be a stable colonizer in the oral cavity, but when the oral cavity undergoes major physiologic changes such as xerostomia, changes to the oral microbial flora can often be found [20]. Lactobacillus , in addition to S. mutans , is a recognized etiologic agent of dental caries.…”

Oral microbiota and mucositis in patients with head and neck cancer undergoing radiotherapy: literature review

“…The result of pronounced and sometimes persistent xerostomia is the change of oral microbiota, producing a significant increase of oral acidogenic cocci in supragingival biofilm, and a significant elevation in salivary levels of cariogenic cocci, particularly Streptococcus mutans [28][29][30] . This phenomenon is cumulative, usually established after 2000 cGy of radiation, accompanying the severity and persistence of xerostomia 17 .…”