BOSTON By the time most patients have symptoms of sinusitis, the physician is dealing with an "already sick sinus," said Jack M. Gwaltney Jr., MD.
Sinusitis usually follows a viral cold or flu-like illness. By that point, the material in the sinus is thick and tenacious. "The point I want to make is that when the secondary bacterial infection does occur, the sinus is already sick, and this is going to affect the treatment," explained Gwaltney, who is professor of internal medicine, epidemiology and virology at the University of Virginia, Charlottesville.
"The management of this disease continues to be a problem," he said.
About 2% of rhinoviruses are complicated by secondary acute bacterial sinusitis. "The question that arises for the clinician, and it is a tough one because we still don't have good laboratory tests to distinguish [the answer] is: is this viral or is this viral and bacterial, which is the case in most of the infections," he said. "Most start as a cold."
Medical students learn that patients with sinusitis present with classic symptoms: purulent nasal discharge, fever, erytheme, pain, tenderness and maxillary toothache. "The problem," said Gwaltney, "is that most people with acute bacterial sinusitis do not have these findings. Either they are not sensitive or they are not specific."
Clinicians should consider sinusitis in a patient who suffers a cold or flu-like illness that does not improve after seven to 10 days. "And that's as good as you can get in making the diagnosis of acute bacterial sinusitis, unless you do a sinus puncture, which of course is not appropriate for routine clinical practice," he said.
Once a clinician diagnoses a bacterial infection, he or she must determine which organism is causing it. Sinus puncture studies have provided enough published information to enable physicians to make an educated guess as to what is causing the problem.
Streptococcus pneumoniae and Haemophilus influenzae cause 50% to 70% of the cases of acute community-acquired sinusitis. Moraxella catarrhalis is also a frequent cause especially in children. Anaerobic bacteria cause about 10% of cases. Other organisms implicated in sinusitis include Streptococcus pyogenes other streptococcal species and Staphylococcus aureus.
Some physicians and parents question the need to treat acute bacterial sinusitis because it is a self-limited disease. Concerns about growing antibiotic resistance have supported the idea that treatment should be withheld. However, sinusitis is not a trivial illness and should be treated, Gwaltney said, explaining how the disease affects the sinuses.
During the first two days of a sinus infection, there is a modest decrease in the ciliary function. Soon after, however, there is marked destruction of the ciliary epithelia cells. "This starts a little earlier with the pneumococcus, which is a little more destructive than the H. influenzae," Gwaltney said, "so that by day four most of the cells that line the sinus cavity have been destroyed.
"The problem is not just to open up the ostea and let the sinus drain, it is a very sick sinus by this point, and it takes a long time for the epithelia to regenerate. So, I think there is good evidence to say that we should treat this infection and treat it effectively."
Still, resistance must be a consideration when treating sinusitis, Gwaltney said. When S. auerus became resistant to penicillin, it did not mean much for sinusitis treatment because it did not cause much sinus disease. When H. influenzae and M. catarrhalis became resistant to ampicillin, it was a concern, but the concern was more economic than medical because there were still treatment options they just cost more, Gwaltney said.
"Now things have really changed. And with the emergence of resistance of the pneumococcus to penicillin and other antibiotics, we are faced with a more serious problem." There is no antibiotic that can be used for all patients with resistant sinusitis.
It is important for a clinician to know the level of resistance in the community in which he or she practices. For instance, 50% of the strains in Gwaltney's community of Charlottesville have either intermediate or high levels of resistance, he said.
"There is no sense looking at highly resistant strains because the oral antibiotics that we have are just not effective against these strains. If your patient has one of those, you just have to be alert and pick that up hopefully before they develop complications. If they do develop a complication, you have to start them on the proper treatment until you get culture sensitivities," he said.
Gwaltney would choose an agent that covers ß-lactamese-producing strains of H. influenzae and M. catarrhalis and would be effective against low to moderate levels of resistant pneumococci. "And with chronic sinus disease, the strategy that makes the most sense and that is not to say that we know for sure that this actually works is to give persistent long-term antimicrobial treatment," he said.
Antibiotic concentrations in the sinus fluid do not correlate to plasma levels, which means that one cannot extrapolate from plasma levels how much of an antibiotic is going to clear the infection in the sinuses.
"An antibiotic that is effective against the four organisms that cause bacterial sinusitis, when given in the proper dose, will give you high bacteriologic cure rates. However, in times that we have not given enough of the antibiotic, we did not get bacteriologic cures until we gave doses that were effective. So there is good evidence that shows that bacteriologic cure does depend on the right antibiotic in the right dose and the right length of treatment," he explained.
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