Objective: To study the bacteriological profile in a healing mastoid cavity.
Methods: This study was a single centre prospective study. Culture swabs from granulations in the mastoid cavity were sent in 40 consecutive patients with squamosal chronic otitis media undergoing mastoidectomy. Cultures were processed for both aerobic and anaerobic bacteria.
Results: Preoperatively: specimens from 26 out of 40 (60.5%) had growth on culture, with 22 (55%) showing only one organism while 4 showing multiple organisms. The commonest organism isolated was pseudomonas aeruginosa (n = 15).At 1 month after mastoidctomy, 11 patients had sterile culture while 29 had growth, of which 26 had aerobic growth and 3 had anaerobic growth. Pseudomonas was seen in 22 patients and staphylococcus aureus in 2 patients. The mean Merchant score was 2.At 3 months: 29 patients (72.5%) had sterile culture from mastoid cavity while 11 patients (27.5%) had growth on culture. All positive cultures were aerobic, including pseudomonas (n = 9) and proteus (n = 2). The mean Merchant score was 1.03. Of the 40 patients, 16 (40%) had a different organism cultured postoperatively compared to preoperative swabs.
Conclusion: Pseudomonas and proteus seem to be the most common organisms responsible for persistent otorrhea after mastoidectomy. Persistent sterile otorrhea was seen in 4 patients (10%) in this group at the end of 3 months. Sterile cultures of preoperative swab are more likely to remain sterile in the postoperative period.
Keywords: Bacteriology; CSOM; Culture; Healed cavity; Healing mastoid cavity.