Oral condition of critical patients and its correlation with ventilator-associated pneumonia: a pilot study

Is the oral microbiome a source to enhance mucosal immunity against infectious diseases?

Mucosal tissues act as a barrier throughout the oral, nasopharyngeal, lung, and intestinal systems, offering first-line protection against potential pathogens. Conventionally, vaccines are applied parenterally to induce serotype-dependent humoral response but fail to drive adequate mucosal immune protection for viral infections such as influenza, HIV, and coronaviruses. Oral mucosa, however, provides a vast immune repertoire against specific microbial pathogens and yet is shaped by an ever-present microbiome community that has co-evolved with the host over thousands of years. Adjuvants targeting mucosal T-cells abundant in oral tissues can promote soluble-IgA (sIgA)-specific protection to confer increased vaccine efficacy. Th17 cells, for example, are at the center of cell-mediated immunity and evidence demonstrates that protection against heterologous pathogen serotypes is achieved with components from the oral microbiome. At the point of entry where pathogens are first encountered, typically the oral or nasal cavity, the mucosal surfaces are layered with bacterial cohabitants that continually shape the host immune profile. Constituents of the oral microbiome including their lipids, outer membrane vesicles, and specific proteins, have been found to modulate the Th17 response in the oral mucosa, playing important roles in vaccine and adjuvant designs. Currently, there are no approved adjuvants for the induction of Th17 protection, and it is critical that this research is included in the preparedness for the current and future pandemics. Here, we discuss the potential of oral commensals, and molecules derived thereof, to induce Th17 activity and provide safer and more predictable options in adjuvant engineering to prevent emerging infectious diseases.

Periodontopathogenic bacteria in subglottic samples from patients undergoing elective intubation for general anesthesia: A pilot study

BACKGROUND

Translocation of periodontal pathogens into the respiratory tract could either cause pneumonia or disrupt local defense mechanisms, predisposing the host to infection by respiratory pathogens. The objective of this pilot study was to evaluate the levels of periodontopathogenic bacteria in subglottic samples of intubated and mechanically ventilated patients and the impact of oral decontamination with chlorhexidine (CHX) on subglottic levels of these microorganisms.

METHODS

Patients scheduled to undergo elective surgical procedures requiring endotracheal intubation and mechanical ventilation for at least 3 hours were included. Following full-mouth periodontal examination, patients were randomly assigned to groups that rinsed preoperatively with 0.12% CHX or 0.9% saline (control). After 3 hours of orotracheal intubation, subglottic contents were collected. Quantification of Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans), Porphyromonas gingivalis (P. gingivalis), and Tannerella forsythia (T. forsythia) in subglottic samples was determined using quantitative real-time polymerase chain reaction. Data were analyzed by Fisher Exact Probability, unpaired Student's t and Mann-Whitney tests.

RESULTS

Of the 69 patients included, 43 completed study participation. There were no differences between control and CHX groups in subglottic detection rates and abundance levels of P. gingivalis (P = 0.59), T. forsythia (P = 0.83) and A. actinomycetemcomitans (P = 0.07). Moreover, our data indicate that periodontal health has no impact on subglottic levels of P. gingivalis, T. forsythia, and A. actinomycetemcomitans.

CONCLUSIONS

Periodontal pathogens were detected in subglottic samples of intubated and mechanically ventilated patients. Moreover, a single CHX rinse prior to endotracheal intubation may have no effect on subglottic contamination by P. gingivalis, T. forsythia, and A. actinomycetemcomitans.