Flash-photometer for nephelometric determinations

A method of screening antibiotics to determine their efficacy against bacteria by testing respective antibiotics for growth inhibiting effect against said bacteria, said method comprising the steps of:

• preparing a series of samples in container of the same geometry, including the bacteria in question and, in the respective samples, different antibiotics;
• permitting said samples to incubate for predetermined periods before exposure to a high intensity light source;
• arranging said sample containers in a fixed predetermined relationship to each other and to said light source to permit all of said samples to receive substantially identical intensity of activating radiation in a first direction from said light source;
• arranging a photographic film to receive light radiated from all of said samples in a second direction substantially perpendicular to said first direction;
• actuating the light source to emit a short duration pulse of activating radiation in said first direction simultaneously into each of said samples;
• exposing said film simultaneously to light radiated in said second direction from said samples so as to provide on the film, when developed, a series of zones corresponding to the respective samples and of various degrees of exposure;
• comparing the optical density of said zones as an indication of the inhibition of said bacteria by the respective antibiotics;
• and
• selecting as the most appropriate antibiotic for combatting said bacteria the antibiotic in the sample which produces the highest degree of optical density in the positive image of the film, or conversely, the lowest degree of optical density in the negative image of the film.