Introduction: Oral colonisation with potential respiratory pathogens (OCRP) is both a risk factor and a potential target for intervention for hospital acquired pneumonia (HAP). However, little is known about colonisation dynamics nor patient factors contributing to OCRP. We investigated OCRP in patients with lower limb fracture with novel real-time PCR assays and used generalised linear modelling to investigate associated patient factors.
Methods: Tongue/throat swabs were taken at Day 0–2, 3, 5, 7 and 14 from patients admitted with lower limb fracture. Demographic data, comorbidities, drug history, recent antibiotic use, number of teeth, presence of dentures, deprivation score and functional indices were recorded. Plaque was scored at Day 0–2, 7 and 14 using the modified Quigley Hein index. Novel multiplex real-time PCR assays were used to detect Streptococcus pneumoniae, Haemophilus influenzae, Eschericihia coli, Streptococcus aureus, MRSA, Pseudomonas aeruginosa and Acinetobacter baumannii. The relationship between OCRP and dental/demographic variables was investigated using generalised linear modelling (binomial). All analyses were undertaken in R (R: A language and environment for Statistical computing, Vienna, Austria).
Results: Samples were collected from 91 patients. Of 73 patients with positive samples, 17 had transient acquisition of a single pathogen and 56 had single (n = 26) or mixed pathogen colonisation (n = 30). Streptococcus pneumoniae was detected most frequently, followed by Haemophilus influenzae. Carriage began within 72 h of admission in the majority of cases, even with E. coli. Streptococcus pneumoniae carriage was highly significantly (**P < 0.01) associated with being ‘fit’ (increased tooth number**, decreased frailty* and comorbidity*) while H. influenzae was associated with increased deprivation**, denture wearing** and frailty**. Streptococcus aureus was associated with recent antibiotic use**, increased comorbidity** and increased dental plaque at admission*.
Conclusions: Interventions to prevent HAP by oral disinfection should commence within 72 h of hospital admission. The hospital environment may not be the source of these organisms.