PURPOSE: To determine the incidence and profile of bacterial colonisation of upper and respiratory tract (URT & LRT) in mechanically ventilated patients and to study the association between colonisation and development of ventilator associated pneumonia (VAP) pneumonia.
METHODS: Fifty critically ill patients (50.7±17.6years,20-84years;M/F:33/17) admitted to the Intensive Care Unit (ICU) were prospectively included within 24 hours of endotracheal intubation. Patients on mechanical ventilation prior to admission, those with community-acquired pneumonia or developing pneumonia within 48 hr of admission and those who either expired or were extubated within 3 days of admission were excluded. Throat swab, endotracheal aspirate (ETA), non bronchoscopic bronchoalveolar lavage (NBAL) were done on alternate days as long as patient received mechanical ventilation, till patient developed colonization or developed VAP based on ACCP criteria. Colonisation was defined as at least two consecutive isolates of pathogenic microorganisms in absence of the disease.
RESULTS: The incidence of colonisation of the URT was 26% (13 patients) and all isolates consisted of ESBL positive gram negative bacteria (GNB). In more than half patients (n=7), similar isolates were detected in the LRT out of which colonisation of URT preceded colonisation of LRT in four patients. On the other hand, incidence of colonisation of LRT was much higher (n=30, 60%) and all the isolates comprised of GNB. Average duration of mechanical ventilation for development of colonisation in URT and LRT was 3.5 days and 4 days respectively. Four patients (8%) developed VAP and in all the cases, it was preceded by LRT colonisation with the same organisms. However, URT colonisation preceded LRT colonization, and subsequently VAP, in only one patient.
CONCLUSION: Colonisation of URT and especially LRT with gram negative bacteria is common in ventilated patients. Although, progression of LRT colonization to VAP is not very common, VAP is likely to be preceded by LRT colonization.
CLINICAL IMPLICATIONS: Gram negative bacteria should be appropriately covered while choosing an empirical antibiotic regimen for VAP. In absence of LRT colonization, the risk of VAP is low.
DISCLOSURE: Gopi Khilnani, No Financial Disclosure Information; No Product/Research Disclosure Information