Aerobic and anaerobic mixtures of human pathogens: a rapid 4-plate counting technique.

A reliable, cheap, labour-saving technique is presented for counting viable organisms in mixtures of aerobic and anaerobic human pathogenic bacteria. Series of 0.1-ml blood agar droplets containing antibiotics are used and only 4 Petri dishes are required. A system of controls makes recognition of any errors of technique particularly simple whilst allowing direct subculture of any unexpected colonies.