OBJECTIVETo explore the characteristics of bacteria isolated from patients with chronic sinusitis (CR) and antibiotic-resistance.

METHODSThe purulent discharges taken from the maxillary sinus and posterior ethmoid sinus of 76 patients during endoscopic sinus surgery were cultured for both bacteria and fungi, then the antimicrobial susceptibility test and beta-lactamase-producing bacteria (beta-LPB) were detected. In the control group, the discharges from the nasal cavity from 10 healthy adults were also cultured for bacteria.

RESULTSTwenty species, including Staphylococcus epidermidis, Escherichia coli, Staphylococcus aureus, alpha-Hemolytic streptococcus and Streptococcus pneumoniae, were cultured from the testing group. The total positive rate of bacteria was 81.8%. The detectable rates of aerobe, anaerobe, gram-positive bacteria and gram-negative bacteria were 83.4%, 16.6%, 56.3% and 43.7%, respectively. The fungi was only detected in 1.4% patients. The antimicrobial susceptibility test demonstrated that Imipenem, Cefotaxime and Amoxicillin-clavulanate were good in vitro activity to aerobic pathogens and Metronidazole, Imipenem and Chloramphenicol was good to anaerobic pathogens. The beta-LPB was detected in 37.7% strains in which Staphylococcus epidermidis, Staphylococcus aureus, alpha-Hemolytic streptococcus and Branhamella catarrhalis were more frequent. Five species including Staphylococcus epidermidis and Escherichia coli etc were cultured from the control group. There was no significant difference of distribution of the same bacteria between the control group and the testing group (P > 0.05).

CONCLUSIONSThe pathogenic bacteria of CR mostly involve aerobes. The antibiotics-resistance of these pathogen is serious. The bacterial infection plays no leading role in CR, so the need of antibiotics should not be excessively emphasized. Before treatment by antibiotics, the antimicrobial susceptibility test should be performed. The broad-spectrum antibiotics containing beta-lactamase inhibitor such as Cefotaxime and Amoxicillin-clavulanate is recommended in condition that the test can not be finished.