Periodontal Status and Subgingival Biofilms in Cystic Fibrosis Adults

The role of oral health, including the level of dental hygiene, accumulation of dental bacterial plaque, and periodontal diseases in the pathogenesis of respiratory infections is usually ignored in the medical care of cystic fibrosis (CF) patients. The oral cavity is a reservoir of many microorganisms; to date, more than 700 oral bacterial species have been identified. Over 400 of them form dental bacterial plaque biofilm and can be isolated from gingival sulcus or gingival pocket. The remaining 300 inhabit other areas, such as the tongue, oral mucosa, carious lesions, and teeth with endodontic infection (Haffajee et al. 2008; Dewhirst et al. 2010). Most oral bacteria are saprophytes of the oral cavity; the species composition of the dental plaque micro-biome is characterized by stability (homeostasis) that may break down, and, under favorable environmental conditions, the plaque microflora may express their virulence (Haffajee et al. 2008). The oral cavity, especially in individuals with poor oral hygiene or periodontal diseases, can also harbor various important pathogenic microorganisms, including respiratory pathogens (Wise and Williams 2013; Souto et al. 2014; Caldas et al. 2015; Vilela et al. 2015).

Periodontitis is a chronic infection of tooth-supporting tissues. The pathogenesis involves a complex of an immuno-inflammatory reaction of the host to a microbial community in the dental plaque. The severity of the periodontal disease results from the interaction between the dental plaque microbiota and the host’s defense mechanisms (Haffajee et al. 2008; Dewhirst et al. 2010). Subgingival plaque bacteria form a specific biofilm complex in which microorganisms become more effectively protected against host defense mechanisms and efficiently use the nutrients (Socransky et al. 1998). The concept of a bacterial complex, introduced by (Socransky et al. 1998), is based on the specific plaque hypothesis that assumes that a specific microbiota is associated with gingivitis or chronic or aggressive periodontitis, and that the pathogenicity of the plaque depends on the presence or increase in the number of specific micro-organisms. Based on the bacterial correlations all of the biofilm’s periopathogens are divided into four groups (complexes). The most pathogenic for periodontal tissues and considered as a marker of periodontitis is the red complex, which includes Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola. The orange complex, directly related to the red one, includes Fusobacterium nucleatum, Prevotella intermedia, Peptostreptococcus micros, and Campylobacter rectus. The yellow complex comprises Streptococcus mitis, Streptococcus oralis, Streptococcus sanguis, and the green complex includes Capnocytophaga gingivalis, Campylobacter concisus, Eikenella corrodens, and Aggregatibacter actinomycetemcomitans serotype a. Also, there are separate periopathogens such as A. actinomycetemcomitans serotype b, Selenomonas noxia, and Actinomyces naeslundii genospecies, which are not related to other groups. Particular importance in the etiopathogenesis of periodontitis is attributed to (Haffajee et al. 2008) that is considered the dominant etiological factor in the initiation and early stage of periodontal disease. Species of individual complexes are closely related. In most cases, species of a particular group appear together, or they are all absent together. This interaction and cooperation between the bacteria of dental plaque biofilm lead to a form of stabilization in which all species exist in harmony and equilibrium with their environment. This biofilm stabilization is named the climax community (Socransky et al. 1998; Haffajee et al. 2008).

The periopathogens are not only responsible for pathological changes in periodontal tissues, but may also be associated with several systemic conditions, including respiratory diseases (Gomes-Filho et al. 2010; Messika et al. 2018). Oral bacteria may disseminate into the lower respiratory tract, increasing the risk of pulmonary infections (Gomes-Filho et al. 2010). Thereby, to reduce the risk of possible autoinfection especially in patients at risk of such infection, there is a need to control periodontal condition regularly.

The aim of this study was to assess the periodontal status of cystic fibrosis patients and to evaluate whether there is a correlation between the bacterial population of the subgingival biofilm and the health status of the periodontal tissues in this group of adults.

Mild dental plaque accumulation (PLI = 0.1–1.0) was detected in 36% of cystic fibrosis patients, moderate (PLI = 1.1–2.0) in 45%, and severe (PLI = 2.1–3.0) in 18%. There was no patient with PLI < 0.1, but this condition is observed only directly after tooth brushing in patients with good oral hygiene. In the vast majority of patients (68%) the GI index ranged between 0.1 and 1.0 indicative of mild inflammation. In 27% of patients, no gingivitis was present (GI < 0.1), and a moderate inflammation (GI = 1.0–2.0) was found in 45%. No patient showed severe gingivitis (GI ≥ 2.1). There was no patient in whom periodontal pocket was recorded (PPD > 4 mm). In 45% of patients, the PPD ranged between 3 and 4 mm, in 18% between 0.5 and 2 mm, and 36% between 3 and 4 mm. There was a very high positive correlation between the following: GI and PLI, GI and PPD, PPD and PLI (p < 0.0001). Quantitative microbial analysis of gingival sulcus revealed that the mean total bacteria count in gingival sulcus in CF patients was 1.3 × 10⁷ ± 3.8 × 10⁷ CFU/ml. There was a very high positive correlation (p < 0.0001) between the number of bacteria and the depth of gingival sulcus (PPD index).

Periopathogens were detected in 50% of CF patients. Based on these results, the patients examined were divided into two groups: 1. CF patients with periopathogens, that is, for whom PCR tests showed the presence of periopathogens, and 2. CF patients without periopathogens, that is, in whom periopathogens were not found in the materials examined (Table I). There was no significant difference in the total bacteria count between the two groups of patients (p > 0.05), but in patients with periopathogens, the GI, PLI, and PPD were significantly higher in comparison to patients without periopathogens (p > 0.05).

Seven out of nine tested periopathogens were detected in examined patients (Table II). A. actinomy-cetemcomitans and E. nodatum were not found in any of them. The average percentage of tested periopathogens within the total bacterial count was 2.42% and ranged from 0.01 to 21.56%. C. gingivalis from the green complex was the most frequently detected. Red complex microorganisms (P. gingivalis, T. forsythia, T. denticola) were present in 9.09% of samples, orange complex (F. nucleatum, P. intermedia, P. micros) in 22.73%, and green (C. gingivalis) in 31.82% (Fig. 1). Moreover, in 9.09% of patients a significantly increased number of periopathogens (C. gingivalis, F. nucleatum, P. intermedia, and P. micros) was detected.

Fig. 1.

Among the many factors influencing the onset and progression of periodontal infection, periopathogens are of key importance, but their presence in the oral cavity is not always manifested. The clinical picture of periodontal disease depends on the balance of the interaction between microbial dental plaque biofilm and host immune response (Haffajee et al. 2008; Dewhirst et al. 2010). In the studied CF patients, there was a high positive correlation between the depth of the gingival sulcus (PPD) and the accumulation of dental plaque (PLI), also between the PPD and gingival bleeding (GI), and between PPD and total number of bacteria in gingival sulcus, confirming the pathomechanism of periodontitis and underscoring the importance of daily removal of dental bacterial plaque, by tooth brushing, as a preventive measure. The dental plaque accumulation index leads to conclusions not only about the current status, but also about the efficiency of hygienic procedures performed by the patient (daily mechano-chemical teeth brushing). However, it does not convey information about the host’s immune response to the bacterial infection or the severity of the inflammation. These factors can be analyzed by gingival indices describing the condition of the gums. The available literature regarding the periodontal status of cystic fibrosis patients shows that CF adult patients, compared to healthy individuals, have less gingival bleeding, with a similar bacterial plaque accumulation (Pawlaczyk-Kamieńska et al. 2018). In our study, despite the widespread presence of bacterial dental deposits in cystic fibrosis patients, none of them has clinical symptoms of periodontal disease. This can be explained by frequent and long-term antibiotic therapy, including via inhalation.

Microbiological analysis of bacterial subgingival plaque in CF patients was conducted by (Caldas et al. 2015). Their studies included 10 cystic fibrosis patients (five chronically colonized by Pseudomonas aeruginosa, and five not colonized) without clinical symptoms of gingivitis or periodontitis. The average age of the chronically colonized patients was 23.8 (17–34 years), and of the not colonized patients, it was age 16.6 (12–27 years). The qPCR PrioAnalyse assay was used for the analysis of bacterial plaque microbiological composition. This test identified nine periopathogens: A. actinomycetem-comitans, P. gingivalis, T. forsythia, and T. denticola from the red complex; F. nucleatum, P. intermedia, P. micros, and C. rectus from the orange complex; and E. corrodens from the green complex.

The analysis of samples revealed seven periopathogens in not colonized patients from the group, and five out of nine analyzed in the chronically colonized group. A. actinomycetemcomitans was not found in any patients. The most frequently detected was F. nucleatum (orange complex), and the second most frequent was E. corrodens (green complex). In our study, the PCR analysis showed seven out of nine the periopathogens tested. Similar to (Caldas et al. 2015), no A. actinomy-cetemcomitans were found. C. gingivalis (green complex) was the most common, followed by F. nucleatum (orange complex).

Reports published to date concerning the presence of oral periopathogens usually relate to generally healthy patients with varying degrees of periodontitis, diagnosed based on history, clinical, and radiological examination (Abiko et al. 2010; Kotslikov et al. 2015; Elamin et al. 2017). The cited studies exclude patients who had used antibiotics in the last three months or anti-inflammatory drugs in the last month. These results report a higher level of periopathogens in individuals with periodontitis compared to patients with healthy periodontium (Abiko et al. 2010). Furthermore, the authors found a positive correlation between the severity of periodontitis and the number of microorganisms, such as A. actinomycetemcomitans, P. gingivalis, P. intermedia, and T. forsythia (Abiko et al. 2010; Kotslikov et al. 2015; Elamin et al. 2017). Their numbers and the ratio to other microbes in the periodontal pockets determine the risk of onset and progression of periodontitis. A high titer of periopathogens does not guarantee disease development but informs of the risk (Abiko et al. 2010). The presented research included cystic fibrosis patients in whom the exclusion of systemic drugs application was not possible. Presumably, in those groups of patients, medications used may affect the microbiological oral condition, probably limiting the pathogenicity of the bacterial plaque biofilm. Unsatisfactory oral hygiene levels suggest that the periodontal risk cannot be ruled out.

Knowledge of the pathomechanisms of periodontitis and possible autoinfection by aspiration of oral microbiome should be taken into account in the medical care of CF patients. The dental biofilm cannot be eliminated, but it can be controlled by daily, regular chemo-mechanical oral hygiene practices performed by the patients. There is a necessity to improve the oral health condition in CF patients, and dentists should be a part of a multi-disciplinary cystic fibrosis team. There is also a need to implement effective strategies for care pathways directed toward maintaining oral health in this group of patients.

Despite the widespread presence of bacterial dental deposits in cystic fibrosis adult patients, none of them has clinical symptoms of periodontal disease, but the presence of periodontal pathogens in subgingival biofilm represents a possible risk factor of this disease in the future.

An unsatisfactory level of oral hygiene in any patient with cystic fibrosis indicates a need to focus on standards of dental care for such patients.