Standardisation of quantitative direct gas liquid chromatography for early detection of bacteria in blood cultures.

Blood cultures with strains of aerobic, facultative and obligate anaerobic bacteria were studied by quantitative direct gas liquid chromatography for early diagnosis of bacteraemias. Small amounts of volatile and nonvolatile fatty acids were detected in uninoculated blood cultures. Bacteroides fragilis produced acetic (27.6 mumol/ml), propionic (1.0 mumol/ml), isovaleric, (0.6 mumol/ml), lactic (4.5 mumol/ml) and succinic (2.7 mumol/ml) acids after 48 h. Blood cultures inoculated with Clostridium perfringens and Fusobacterium nucleatum produced large amount of butyric acid (2.5 and 18.8 mumol/ml respectively) along with acetic, propionic, lactic and succinic acids on day 2 of incubation. Blood cultures with Escherichia coli, Salmonella typhi, Staphylococcus aureus, beta-haemolytic streptococci (group A) produced only acetic, lactic and succinic acids. Pseudomonas aeruginosa produced only small amounts of succinic (0.6 mumol/ml) and acetic acids (2.4 mumol/ml) on day 5 of incubation. Blood cultures inoculated with anaerobic bacteria produced multiple volatile fatty acids within 24 to 48 h of incubation. Since these acids could be detected earlier than the organism in cultures, they may be useful in the early diagnosis of anaerobic bacteraemias/septicaemias.