The association between oral bacteria, the cough reflex and pneumonia in patients with acute stroke and suspected dysphagia

OBJECTIVE: To establish how oral bacteria are related to cough sensitivity and pneumonia in a clinical stroke population. BACKGROUND: Stroke patients are at risk of colonisation by respiratory pathogens due, in part, to sudden discontinuation of effective oral hygiene. When combined with reduced cough reflex sensitivity, aspiration of contaminated oropharyngeal contents and can lead to pneumonia. Relationships between oral bacteria, cough sensitivity and pneumonia have not been established. MATERIALS AND METHODS: A total of 102 patients with acute stroke underwent saliva sampling and cough reflex testing at admission to hospital, discharge and one month. A qPCR assay compared levels of bacteria in saliva. Pneumonia events were recorded. RESULTS: Relative levels of bacteria were lowest at admission to hospital (6.04 x 10(-6) ). There was a slight (non-significant) increase in bacterial levels at discharge (1.69 x 10(-2) , P = .73). By one month, bacterial levels had significantly increased (9.17 x 10(-2) ) relative to admission [P < .001] and discharge [P < .001]. Pseudomonas aeruginosa, Klebsiella pneumoniae and Escherichia coli are not typically found in healthy mouths, yet were detected in 22% of patients during hospitalisation. Combined bacterial levels measured at one month was associated with pneumonia (P = .004) but there was no relationship to cough sensitivity. CONCLUSION: Acute stroke patients were at increased risk of colonisation from respiratory pathogens throughout their recovery. The presence of these pathogens in saliva at one month was associated with adverse respiratory events. Data support the development of protocols to explore risk factors and sequelae of microbiological changes in stroke.