Wednesday March 11, 2009
Glucose in bronchial secretions and MRSA

Interesting paper by Philips et al inThorax reports a possible association between a positive culture for MRSA from bronchial aspirates from patients in ICU and abnormally high levels of glucose in the bronchial aspirates (ranging from 2.7 to 4.4 mmol/l = 50-80 mg/dl).

Background: The risk of nosocomial infection is increased in critically ill patients by stress hyperglycaemia. Glucose is not normally detectable in airway secretions but appears as blood glucose levels exceed. We hypothesise that the presence of glucose in airway secretions in these patients predisposes to respiratory infection.
Methods: An association between glucose in bronchial aspirates and nosocomial respiratory infection was examined in 98 critically ill patients. Patients were included if they were expected to require ventilation for more than 48 hours. Bronchial aspirates were analysed for glucose and sent twice weekly for microbiological analysis and whenever an infection was suspected.

Results: Glucose was detected in bronchial aspirates of 58 of the 98 patients.

• These patients were more likely to have pathogenic bacteria than patients without glucose detected in bronchial aspirates (relative risk 2.4 (95% CI 1.5 to 3.8)).
  
• Patients with glucose were much more likely to have methicillin resistant Staphylococcus aureus (MRSA) than those without glucose in bronchial aspirates (relative risk 2.1 (95% CI 1.2 to 3.8)).
  
• Patients who became colonised or infected with MRSA had more infiltrates on their chest radiograph, an increased C reactive protein level, and a longer stay in the intensive care unit.

Conclusion: The results imply a relationship between the presence of glucose in the airway and a risk of colonisation or infection with pathogenic bacteria including MRSA.



References:

Glucose in bronchial aspirates increases the risk of respiratory MRSA in intubated patients - Thorax 2005;60:761-764;