Ventilator-associated sinusitis: microbiological results of sinus aspirates in patients on antibiotics.

Background: The efficacy of systemic antibiotics on the treatment of ventilator-associated infectious maxillary sinusitis (VAIMS) is debated. The objective of this study was to determine the etiologic diagnosis of VAIMS in patients receiving antibiotics.
Methods: Patients mechanically ventilated for more than or equal to 72 h, who had persistent fever while on antibiotics for more than or equal to 48 h, underwent computed tomography scan followed by transnasal puncture of involved maxillary sinuses. VAIMS was defined as follows: fever greater than or equal to 38 degrees C, radiographic signs (air fluid level or opacification of maxillary sinuses on computed tomography scan), and a quantitative culture of sinus aspirate yielding more than or equal to 103 colony-forming units/ml.
Results: Twenty-four patients had radiographic signs of sinusitis. The mean +/- SD prior durations of mechanical ventilation and antibiotic exposure were 9.5 +/- 4.7 days and 6 +/- 4 days, respectively. Six unilateral and nine bilateral VAIMS were diagnosed in 15 patients. The median number of etiologic organisms per patient was two (range, one to four). The bacteriologic cultures yielded gram-positive bacteria (n = 21), gram-negative bacteria (n = 22), and yeasts (n = 5). Forty percent of causative agents were susceptible to the antibiotics prescribed. Seven patients with VAIMS developed 10 concomitant infections: ventilator-associated pneumonia (n = 5), urinary tract infection (n = 3), catheter infections (n = 2). In all cases of ventilator-associated pneumonia, the implicated agents were the causative agents of VAIMS.
Conclusion: In VAIMS patients on antibiotics, quantitative cultures of sinus aspirates may contribute to establish the diagnosis. The frequent recovery of microorganisms susceptible to the antimicrobial treatment administered suggests that therapy of VAIMS with systemic antibiotics may not be sufficient.