Bacteria from solid tumours

Bacteria were grown from 63 (69%) of 91 specimens from necrotic tumours in 63 patients. Of the tumours, 14 were abdominal, 5 pelvic, 23 of the head and neck, 4 of the lungs, 4 mediastinal, 2 lymphatic, 3 of the breast, and 8 were miscellaneous. Aerobic or facultatively anaerobic bacteria only were present in 12 (19%) specimens, anaerobes only in 10 (16%), and mixed aerobic and anaerobic bacteria in 41 (65%). A total of 83 anaerobic and 47 aerobic and facultatively anaerobic bacteria were isolated. The predominant anaerobic bacteria were Bacteroides spp. (36 isolates), and anaerobic cocci (21) and Propionibacterium acnes (22). The aerobic and facultatively anaerobic bacteria most frequently isolated were Staphylococcus aureus, alpha-haemolytic streptococci, Escherichia coli (seven isolates each), S. epidermidis, Klebsiella pneumoniae and Pseudomonas aeruginosa (five isolates each). These data demonstrate that infection of tumours is usually polymicrobial.