A Comparison of the Bacterial Culture Results of Maxillary Sinus Mucosa and Pus Collections for Chronic Maxillary Rhinosinusitis

Objective: Although maxillary antral taps are the standard for collecting pus for culture, they sometimes reveal no growth. Intraoperative mucosal cultures are another method to collect pathogen samples. This study compared aerobic bacterial cultures from mucosa and pus from chronic maxillary rhinosinusitis patients. Methods: A prospective study of 22 chronic maxillary rhinosinusitis patients was conducted. Antral pus and mucosa collected during endoscopic sinus surgery were immediately sent to a microbiological laboratory. The degree of concordance between maxillary sinus mucosa aerobic bacterial cultures and pus cultures was then analyzed. Results: Twenty-seven specimens were obtained for the cultures. The proportions of positive mucosal and pus cultures were 40.74% and 51.85%, respectively. The common aerobic pathogens from the two culture techniques were Pseudomonas aeruginosa and Staphylococcus aureus. A concordance between the pus and mucosal cultures was demonstrated by 19 out of 27 specimens (70.37%). Compared with the pus cultures, the mucosal cultures had a specificity of 84.62% (95% CI, 54.55%-98.08%), a sensitivity of 57.14% (95% CI, 28.86%-82.34%), a predictive value of a positive result of 80% (95% CI, 50.83%-93.93%), and a predictive value of a negative result of 64.71% (95% CI, 48.96%-77.80%). Conclusion: Similar pathogenic bacteria were recovered from the mucosa and pus. Given the high degree of similarity of the bacteria found, the good concordance rate, and the high specificity and positive predictive value of the mucosal cultures compared with the pus cultures, mucosal cultures should be a reference standard and an option when pus is unavailable, especially with immunocompromised patients

Identification of Uncommon Pathogenic Bacteria by MALDI-TOF Mass Spectrometry Using a Custom Library of Siriraj Hospital

Objective: Matrix Assisted Laser Desorption Ionization Time-Of-Flight mass spectrometry (MALDI-TOF MS) is a rapid and cost-effective technique that serves as an alternative method for bacterial identification in microbiology laboratories. This study aimed to determine the performance of MALDI-TOF MS for identifying uncommon and/ or fastidious bacteria comparing with automated identification method. Methods: We observed the performances of original and extended databases after adding of in-house MALDI-TOF MS database for a total of 54 isolates belonging to 16 genera of uncommon and/or fastidious bacteria. Results: The extended database improved identification of these bacteria significantly except for Listeria monocytogenes and Elizabethkingia meningoseptica. Conclusion: This study provides a possibility for identification of uncommon and/or fastidious bacteria by MALDI- TOF MS method