Rapid Methods for Biochemical Testing of Anaerobic Bacteria

Rapid biochemical tests for nitrate, indole, gelatin, starch, esculin, and o-nitrophenyl-beta-D-galactopyranoside were performed on 112 strains of anaerobic bacteria. All tests were incubated under aerobic conditions, and results were recorded within 4 h. The tests for nitrate, indole, and starch showed a 95% or greater correlation when compared to the standard biochemical tests. Tests for esculin and gelatin showed an agreement of 86 and 77%, respectively. PathoTec test strips for nitrate, indole, esculin, o-nitrophenyl-beta-D-galactopyranoside, Voges-Proskauer, and urease were also tested and showed encouraging results.     

Epidemiological Tracing of Pseudomonas aeruginosa: Antibiogram and Serotyping

The spread of a particular strain of Pseudomonas aeruginosa through a pediatric burn unit was monitored using serological typing and antibiotic susceptibility data.     

Comparison of Macroscopic Examination, Routine Gram Stains, and Routine Subcultures in the Initial Detection of Positive Blood Cultures

Blood was cultured in two vaccum bottles containing Columbia broth with sodium polyanethol sulfonate and CO₂. Filtered air was admitted to one bottle, and the bottles were incubated at 35 C until growth was detected or for a maximum of 7 days. Bottles were examined daily for macroscopic growth. Gram stains were made routinely on the 1st, 4th, and 7th days, and samples were routinely subcultured to sheep blood agar (incubated in GasPak jar) and chocolate agar (incubated in CO₂) on the 1st and 4th days of incubation. Of 1,127 positive blood cultures, 65% were first detected by macroscopic examination, 23% were first detected by Gram stain, and 12% were first detected only by subculture.     

Steady-state and limit cycle activity of mass of neurons forming simple feedback loops (I): lumped circuit model

The neurons in the mammalian olfactory bulb sustain two types of synaptic feedback. The periglomerular cells excite each other and form a positive feedback loop. The mitral-tufted cells are excited by periglomerular neurons, and they excite granule cells and are inhibited by them. The last two neural populations form a negative feedback loop. This work contains mathematical proofs for the existence of steady state unvarying activity in periglomerular neurons, and of steady state oscillatory activity of mitral-tufted and granule cells, which is manifested in the EEG. The following predictions are made. 1) The level of mean ongoing pulse activity of the periglomerular population is determined by peripheral sensory and centrifugal input. 2) The interaction of mitral and granule populations determines a limit cycle detectable in the EEG. 3) The frequency of the limit cycle is determined by periglomerular and centrifugal input. 4) The steady and oscillatory pulse rates are stable, and if they are perturbed, they return to the levels preceding perturbation.     

Evaluation of a New Incubation-Type Indole Strip Test

A total of 189 of Enterobacteriaceae and three strains of Clostridium perfringens were tested with a new incubation-type indole paper strip. This 4-hr incubation test gave the same results as a standard 48-hr indole test, except with some strains of Proteus rettgeri. Results with P. rettgeri varied somewhat according to the medium upon which the organisms had been grown.