Exploring the link between oral bacteria

Project Name

Exploring the link between oral bacteria and hospital acquired pneumonia in hip fracture patients using a novel screening assay




October 2008 - January 2013

Project Collaborators



MRC,  Supported by NIHR UKCRN study portfolio

Project Description



Is oral colonisation with opportunistic respiratory pathogens a risk factor for subsequent pneumonia in older people with lower limb fracture in hospital?


  • Develop a multiplex real time PCR assay which detects 8 major respiratory bacterial pathogens
  • Determine the incidence, prevalence and significance of oral colonisation with respiratory pathogens in older patients with lower limb fracture


Colonisation with a potentially pathogenic oral flora may be associated with hospital acquired pneumonia (HAP) in older people.  Few HAP studies have examined both clinical and microbiological variables in a prospective manner. Oral hygiene may be a modifiable risk factor for HAP in high risk older persons. A rapid assay such as polymerase chain reaction (PCR) would allow screening of high risk patients to be undertaken within existing microbiology laboratories in a time-efficient manner.


  • A 5-well real time multiplex PCR assay was designed for Pseudomonas aeruginosa, Staphylococcus aureus, MRSA, Haemophilus influenzae, Streptococcus pneumoniae, Escherichia coli, Klebsiella pneumoniae and Acinetobacter baumannii and tested against clinical isolates for sensitivity and specificity.
  • 93 patients with lower limb fracture and age>65 were recruited, and a series of 5 anonymised tongue and throat swabs were taken.  Demographic, dental (tooth count and a series of 3 plaque scores) and clinical details were recorded.  Complications including pneumonia were noted through weekly case notes review until discharge or death.  Patients were followed up to 3 months after discharge by two telephone calls to patients and GP.
  • DNA was extracted from the swabs and analysed using the assay described above.
  • Results are being analysed using mathematical modelling