Microbiology of chronic sinusitis.

Much controversy still exists about the role of viruses, bacteria and fungi in sinusitis. Until recently, it was not really known that the sinuses take part in the infectious process of a common cold (viral rhinitis). Indeed, CT scans show that in the vast majority of otherwise healthy volunteers with a common cold, and without a previous history of recurrent or chronic sinusitis, the sinuses are involved too. A viral rhinitis alone, however, does not seem to be able to elicit a "clinical" acute sinusitis. Bacteria determine the clinical picture and outcome of sinusitis. There is not much controversy about the role of bacteria in acute sinusitis, S. pneumoniae, H. influenzae and M. catarrhalis being the most frequently involved bacteria. Much more conflicting reports are published about the normal flora of the sinuses, the role of anaerobes and the microbiology of chronic sinusitis. In this chapter the defense and pathophysiologic mechanisms of viral, bacterial and fungal infection of the nasal and sinusal mucosa are described. It is postulated that, although bacteria are very important in acute sinusitis, their role in chronic sinusitis is minimal, the bacteria being opportunistic colonisers.