Warren, Edward

Two liquid blood culture media, Tryptic soy broth (TSB) and Thiol broth, containing sodium polyanetholsulfonate were compared in 8,654 cultures. Pseudomonas and Corynebacterium (including Propionibacterium ) were isolated significantly more frequently ( P < 0.001) from TSB than from Thiol. Escherichia coli, Haemophilus , and Bacteroidaceae were isolated more frequently in TSB; however, the differences were not statistically significant. In no instance was Thiol superior to TSB in detecting bacteremia. In an additional 2,977 cultures, aerobic and anaerobic Vacutainer culture tubes with supplemented peptone broth were inoculated in parallel with TSB and Thiol. Significantly greater rates of detection ( P < 0.01) in TSB or Thiol were noted with Pseudomonas, E. coli, Enterobacter , viridans, and group A streptococci, Bacteroidaceae, and staphylococci.

In a comparison of tryptic soy broth and Columbia broth, two blood culture media containing sodium polyanetholesulfonate, there were 589 positive cultures (excluding presumed contaminants). The two media were equivalent in performance except for lower detection rates for Staphylococcus aureus ( P < 0.01) and Pseudomonas aeruginosa ( P = 0.05) and a higher detection rate for Bacillus ( P < 0.01) in Columbia broth. No significant differences were noted in time intervals to detection of positivity. Routine subcultures on the 1st and 5th days of incubation provided the initial detection of 18.1% of the positive cultures.

McFarland barium sulfate standards prepared in 1952 were compared spectrophotometrically with freshly and identically prepared standards; the results were nearly identical.

Since the microbiological assay of the antibiotic content of serum generally requires 18 to 24 hr of incubation, results of such procedures may not become available in time to make appropriate adjustments in subsequent dosages of antibiotic. A 4-hr bioassay for determining concentrations of gentamicin in serum has been developed in which Staphylococcus aureus ATCC 6538P is used as the test organism. Poured plates have yielded satisfactory results after storage at 4 C for 5 days. Results of the 4-hr procedure agree closely with those of a conventional 18-hr disc-plate assay performed with the same test organism.