This report describes a case of septicemia and meningitis secondary to dog bites by two different dogs on two consecutive days. The case is noteworthy because of the unusual characteristics of the etiologic agent and the inability to place the etiologic agent into any currently defined genus or to identify it by the existing systems of classification. The organism is a small, thin, Gram-negative bacillus after 24 hours of incubation on blood agar; after prolonged incubation, it becomes filamentous. The organism is catalase- and oxidase-positive, hydrolyzes esculin, and forms acid in glucose, xylose, and maltose after 21 days' incubation. The organism does not manifest lysis on sheep blood agar, and does not grow on MacConkey, Salmonella-Shigella, Centrimide, nutrient, or Kligler iron agars. The tests for urea, nitrate reduction, and indol are negative. The unidentified Gram-negative bacillus showed susceptibility to all antimicrobials tested except gentamicin.

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A survey of the content and composition of lipids from isolated cell walls of Pseudomonas aeruginosa and Brucella abortus was made. The following results are average values from several experiments. The readily extractable lipids made up 15.7% and the firmly bound lipids 8.7% of the dry weight of the cell walls of P. aeruginosa. The readily extractable lipids of B. abortus cell walls accounted for 11.4% and the firmly bound lipids 6.4% of the dry weight of the walls.The readily extractable lipids were further separated into phospholipids, free fatty acids, and neutral lipids. These lipids of P. aeruginosa cell walls contained 44.9% phospholipids and 52.9% free fatty acids and neutral lipids. In B. abortus cell walls the phospholipids accounted for only 22.1% of the free lipids whereas the free fatty acids and neutral lipids made up 76.1%.The phospholipids of P. aeruginosa and B. abortus were shown by thin-layer chromatography to be composed of four and seven components respectively. The bulk of the phospholipids was phosphatidyl ethanolamine and diphosphatidyl glycerol of the cardiolipin type. Lysophosphatidyl ethanolamine was also present in both organisms. The presence of phosphatidyl choline could not be demonstrated conclusively since choline could not be detected in the hydrolytic products of the phospholipids; however, infrared spectra of the total lipids and of the phospholipids of both P. aeruginosa and B. abortus showed absorption bands at 970 cm−1 which are characteristic of phosphatidyl choline.Gas–liquid chromatography of the free fatty acids of P. aeruginosa showed the major portion of these acids to be C16 and C18 saturated and monounsaturated fatty acids. The bulk of the free fatty acids of B. abortus consisted of C18 saturated, monounsaturated, and polyunsaturated (C18:2) together with lesser amounts of C16 saturated and monounsaturated acids. Two components were tentatively identified as C19 cyclopropane and C19:0 fatty acids respectively. Small amounts of both C12 and C14 saturated fatty acids were found in both organisms. No hydroxy fatty acids could be identified in either P. aeruginosa or B. abortus.Calcium and magnesium, determined by atomic absorption spectrophotometry, were associated with all the phospholipid components in both organisms. However, the largest quantities of calcium and magnesium were found in the phospholipid components, phosphatidyl ethanolamine and diphosphatidyl glycerol. Trace amounts of zinc were present in all phospholipid components of the cell walls of both microorganisms. Manganese was not detected.

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, nine cases of Pseudomonas aeruginosa septicemia occurred in a high-risk nursery. The epidemiology of the outbreak was studied by pyocin production, pyocin sensitivity, serological typing, antibiotic susceptibility, and phenotypic properties such as colonial morphology, pigment, and hemolysis. Ten isolates of P. aeruginosa were recovered from 9 newborn infants and from 13 environmental sources. Twenty-one of the 23 isolates had identical pyocin production patterns against 60 different indicator strains and were of the same serotype. These 21 isolates were designated as the "outbreak strain"; the other 2 isolates had no epidemiological significance. The results of pyocin sensitivity, antibiotic susceptiblity tests, and phenotypic properties were dissimilar. They would yield incorrect epidemiological conclusions if used alone. The outbreak strain dissociated in vitro and these phenotypic changes accounted for the variable results by the latter three typing methods. Although the precise mode of introduction of the organism into the nursery could not be determined in retrospect, the epidemiological data strongly suggested that one infant contracted a P. aeruginosa infection, and this strain spread throughout the nursery by means of contaminated resuscitation equipment.