Acinetobacter is the most common pathogen associated with late-onset and recurrent ventilator-associated pneumonia in an adult intensive care unit in Saudi Arabia.

Background: The guidelines for initial empiric antimicrobial therapy for ventilator-associated pneumonia (VAP) are highly dependent on the type of causative pathogen and the time of diagnosis. The objective of this study was to examine the microbial causes of VAP and describe any variability by the timing of VAP onset and over time.

Methods: A prospective surveillance study was conducted in the adult general intensive care unit of a tertiary care hospital in Riyadh, Saudi Arabia. Microbial isolates obtained from blood and different respiratory specimens of patients diagnosed with VAP (using the US Centers for Disease Control and Prevention definition) between August 2003 and June 2009 were included.

Results: A total of 457 pathogens were identified during the study; 380 (83.2%) were associated with primary VAP and 77 (16.8%) were associated with recurrent VAP. Of primary VAP pathogens, 159 (41.8%) were associated with early-onset (<5 days) and 221 (58.2%) were associated with late-onset (≥5 days) VAP. The most common pathogen identified was Acinetobacter spp (26.5%), followed by Pseudomonas aeruginosa (21.7%), Staphylococcus aureus including methicillin-resistant S. aureus (MRSA) (15.3%), Klebsiella spp (6.8%), Haemophilus spp (6.1%), and Enterobacter spp (5.0%). Acinetobacter spp and MRSA were significantly associated with late-onset VAP while Haemophilus spp and Streptococcus pneumoniae were significantly associated with early-onset VAP. Acinetobacter spp was the only pathogen associated with recurrent VAP and its incidence showed a significant increasing trend during the study period. Acinetobacter spp was significantly associated with prolonged ventilation, sedation, and nasogastric intubation.

Conclusions: Acinetobacter baumannii is the most common and increasingly important pathogen associated with VAP in our patients, especially late-onset and recurrent VAP.