The sinuses provide a good place for any bacteria to grow. Recent studies have identified both aerobic and anaerobic organisms and fungi growing within the sinuses. This makes the choice of picking an antibiotic difficult, and you may find that your physician wants to put you on more than one antibiotic during a single course of treatment. Although complicated, this is a correct choice if your doctor believes that your infection is being caused by multiple types of bacteria. The most common bacteria that cause sinusitis are Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. Others include Staphylococcus aureus and Pseudomonas aeruginosa, which often cause the more aggressive infections.
There has been a concern in recent years that there is an increased resistance in H. influenzae strains (54 percent resistant to Ampicillin), and M. catarrhalis (74 percent resistant to Ampicillin). It also appears that there is increasing resistance of Streptococcus pneumoniae to various antibiotics. Methicillin-resistant Staphylococcus aureus and P. aeruginosa tend to cause more aggressive infections and are harder to resolve.
Often, the first choices for treating CAID symptoms are amoxicillin, trimethoprim-sulfamethoxazole, and erythromycin. As bacteria become more resistant to certain antibiotics, physicians are tending to choose newer versions over old standbys. The circulating bacteria usually have not had time to develop resistance to these newer antibiotics, so they may be more effective. However, the older antibiotics may still be effective, and in many cases are less expensive than the newer antibiotics. The following sections discuss the types of antibiotics used to treat CAID.