Klebsiella pneumoniae as a spoilage organism in mozzarella cheese.

A high concentration of total and fecal coliforms (5 x 10(8) and 3 x 10(7) cfu/g, respectively) was observed in samples representative of two production lots of Mozzarella cheese from a local dairy. Contamination was manifested by the swelling of plastic pouches and the formation of gas holes in Mozzarella cheese. Aerobic and anaerobic sporeformers, heterofermentative lactic acid bacteria, propionibacteria, and yeasts were absent. Of the 41 isolates identified, there were 37 Klebsiella pneumoniae, 2 Klebsiella oxytoca, 1 Enterobacter aerogenes, and 1 Escherichia coli. Exposure at 63 degrees C for 15 min caused the death of all total and fecal coliforms.