Endoscopically directed middle meatal cultures vs computed tomographic scans in the diagnosis of bacterial sinusitis in intensive care units

Abstract

Purpose: The objective of the study was to evaluate the accuracy of endoscopically directed middle meatal cultures in the diagnosis of bacterial sinusitis in intensive care unit (ICU) patients in comparison with computed tomographic (CT) scans.

Patients and methods: The study was conducted at Alexandria University Hospitals on 51 ICU patients with occult fever and clinical signs suggestive of sinusitis. Sinus CT scans were done for all patients, and Calgi swabs were obtained from the middle meatus bilaterally under endoscopic vision using sterile endoscopes with avoidance of any contamination of the swabs. The results of middle meatal cultures were compared with the results of CT scans.

Results: Radiologic signs of sinusitis were bilateral in 10 patients (19.6%), unilateral in 31 patients (60.8%), and negative in 10 patients (19.6%). Middle meatal swabs yielded positive cultures on both sides in 13 patients (25.5%) and on one side in 27 patients (52.9%). On the other hand, the cultures were negative in 11 patients (21.6%). Middle meatal cultures had a sensitivity of 92.8%, a specificity of 80.0%, and an accuracy of 90.2% in comparison with CT scans. Polymicrobial colonization was more frequent than monomicrobial colonization. The organisms isolated most frequently were coagulase-negative staphylococci, Staphylococcus aureus, and Pseudomonas aeurginosa. Of 47 patients with actual or previous intubation, 38 (80.9%) had positive cultures. In addition, 92.3% of patients with unilateral positive cultures acquired sinusitis on the same side of previous intubation.

Conclusions: The data of the present study indicated that endoscopically directed middle meatal cultures had high positive and negative predictive values and accurately diagnosed bacterial sinusitis and identified the causative bacteria with high sensitivity and specificity in comparison with the criterion standard CT scans. The procedure is simple, noninvasive, and can be easily performed at the bedside without discomfort or morbidity. Based on our data, the procedure can be considered as a trustworthy substitute to sinus CT scans in ICU patients especially when it is difficult to transport the patients for imaging. Computed tomographic scans can, therefore, be reserved for patients who do not respond to culture-specific antibiotherapy. A further advantage of this approach is avoidance of the cumulative effect of unnecessary radiation. The study also confirmed the role of nasogastric and nasotracheal intubation in the pathogenesis of ICU sinusitis.