Preliminary study on detecting corynebacteria in pus of granulomatous mastitis patients

Objective To explore the detection method of corynebacteria in pus samples from granulomatous mastitis patients. Methods The 37 pus samples from 37 patients who were diagnosed with granulomatous mastitis in the Breast Disease Center, Guangdong Women and Children’s Hospital from June 2016 to February 2017 were prospectively analyzed. The common blood plate and high-fat blood plate were used for bacterial culture and PCR to detect the bacteria in pus. The positive rate of corynebacteria and the consistency of different detection methods were analyzed. Rates were compared using the paired χ2 test (McNemar) and the Kappa consistency test. Results In 37 pus samples that were simultaneously subjected to high-fat blood plate culture and PCR, the positive rate of corynebacteria was 35.1% (13/37) in high-fat blood plate culture, and 48.6% (18/37) in PCR, indicating no significant difference (P=0.063). The two methods presented a high consistency (Kappa =0.728, P<0.001). In 24 pus samples that were simultaneously subjected to common blood plate culture, high-fat blood plate culture and PCR, the positive rate of corynebacteria in high-fat blood plate culture was 50.0% (12/24), significantly higher than 16.7% (4/24) in common blood plate culture (P=0.008). The positive rate of corynebacteria was 66.6% (16/24) in PCR, indicating no significant difference compared with the rate in high-fat blood plate culture (P=0.125). The two methods presented a high consistency (Kappa =0.667, P=0.001). The diagnostic competence between common blood plate culture and PCR was significantly different (P<0.001). Conclusions It is easier to culture corynebacteria in high-fat blood plate, which can be easily prepared. This new culture method is worthy of clinical application. Key words: Granuloma; Mastitis; Corynebacterium; Bacteriology