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Biomedical subjects

G K Morris

Publications and source records attributed to G K Morris.

85 records · Page 5Linked to original sources
PubMed1971

New method of isolating Salmonellae from milk.

The use of a cotton gauze swab and subsequent culture of the swab was found to be a more sensitive method for isolating Salmonella from liquid milk than the revised procedure of North. The swab method was found to be as sensitive as the North procedure for recovering Salmonella when incubated at 37 C but more sensitive when incubated at 43 C. Incubation of the swab cultures at the elevated temperature of 43 C gave good results when Salmonella was present at levels as low as one per liter. Swabs exposed to milk contaminated with 100 Salmonella per liter remained positive even when subsequently washed for 2 hr in noncontaminated milk. Bismuth sulfite agar and Brilliant Green sulfadiazine agar were equally effective for isolating Salmonella from broth cultures; use of both media resulted in maximal isolations.

Agar↗
PubMed1970

Salmonellae in fish meal plants: relative amounts of contamination at various stages of processing and a method of control.

Previous studies have shown that Menhaden fish meal, a common ingredient of animal feeds, is frequently contaminated with salmonellae. Animals that eat contaminated feed may become infected. If they, in turn, are eaten by humans, they may be a means by which salmonellae are introduced into the human population. Epidemiological studies of the fish-meal industry were carried out to determine the sources of salmonellae in fish meal and the factors affecting the persistence and survival of salmonellae during the processing of fish meal. Examination of 190 fish immediately after they came from the Gulf of Mexico revealed no salmonellae, but salmonellae were frequently isolated from samples of fish taken from the boats when they arrived at the plants. Salmonellae were also frequently isolated from dockside water at each of the plants. Approximately 50% of the samples taken in the raw fish processing areas were contaminated with salmonellae. The percentage of samples yielding salmonellae decreased progressively through the various sequences of processing, but more than 15% of the samples taken from the finished products were also positive. Salmonellae were isolated from the raw area of the plant most frequently while the plant was operating and less frequently when the plant was idle, whereas in the processing area of the plant the reverse was true. Salmonellae appeared to survive and multiply in the processing area of the plant while the plant was idle, which resulted in contamination of the first portion of each day's production. Salmonellae in the processed fish meal were reduced to nondetectable levels by reprocessing the first 45 min of each day's production.

Animal Feed↗
PubMed1970

Comparison of media for direct isolation and transport of Shigellae from Fecal specimens.

Xylose-lysine-deoxycholate (XLD) agar, SS agar, and MacConkey agar for isolating shigellae from fecal specimens were compared. XLD agar was superior to both SS agar and MacConkey agar for isolating Shigella sonnei, and both XLD and SS agar were superior to MacConkey agar for isolating S. flexneri. Direct plating of the fecal specimens in the field resulted in a greater yield of shigellae as compared to transporting specimens to the laboratory either in holding media or enrichment broth. Buffered glycerol saline was superior to other transport media evaluated, yielding 83% of shigella isolates when plated within 48 hr as compared to direct plating. The combination of XLD agar and SS agar is recommended for direct isolation of shigellae, and, whenever possible, these solid media should be taken to the bedside and inoculated directly.

Agar↗
PubMed1970

Salmonella contamination in a poultry-processing plant.

Bacteriological examination of 1,427 samples from a poultry-processing plant over a 2-year period yielded 202 (14.2%) cultures positive for salmonellae. The results indicate that contamination is reduced by washing procedures within the plant but that recontamination of the carcasses occurred in at least two different stages of processing, i.e., during evisceration and chilling. There was evidence of spread of salmonellae from flock to flock during the serial processing of flocks, but the spread was usually not extensive. The serotypes of salmonellae isolated in this study were similar to those of chicken origin reported from other areas of the country.

Agar↗
PubMed1970

Influence of incubation temperature and sodium heptadecyl sulfate (Tergitol No. 7) on the isolation of salmonellae from pork sausage.

Cultures of 68 samples of fresh pork sausage purchased locally were incubated at 37 and 43 C, with and without Tergitol No. 7 (sodium heptadecyl sulfate) added to the tetrathionate-Brilliant Green enrichment broth. The results indicated an advantage in incubating the tetrathionate broth at 43 C rather than 37 C in attempting to isolate salmonellae from pork sausage. Without Tergitol, more samples were positive at 43 C than at 37 C, but with Tergitol there was no difference. The higher temperature suppressed the competing gram-negative bacteria and permitted Salmonella to grow in relatively pure culture, thus providing an advantage for isolating and identifying the organisms. Tergitol dispersed and emulsified the fat which improved the isolation of Salmonella when the cultures were incubated at 37 C but not at 43 C. Brilliant Green-sulfadiazine agar was superior to bismuth sulfite agar for isolating salmonellae from tetrathionate broth cultures of fresh pork sausage.

Agar↗
PubMed1965

Inhibition of Growth of Lactobacillus bulgaricus by Purine Deoxyribonucleotides.

Morris, George K. (University of Georgia, Athens), and William L. Williams. Inhibition of growth of Lactobacillus bulgaricus by purine deoxyribonucleotides. J. Bacteriol. 90:715-719. 1965.-An inhibition of growth of Lactobacillus bulgaricus GS was observed with deoxyadenylic acid and deoxyguanylic acid. Deoxynucleotides of cytosine, thymine, and uracil, and the deoxynucleosides of adenine, guanine, cytosine, and thymine were inactive as inhibitors. The inhibition was reversed by liver extract (a crude source of two unidentified growth factors for this organism). With suboptimal concentrations of liver extract, the inhibition was reversed by nucleotides of adenine, guanine, uracil, cytosine, and thymine. When the medium contained partially purified sources of the two growth factors rather than crude liver extract, fewer compounds reversed the inhibition. Adenylic acid and guanylic acid reversed the action of either inhibitor. Inosinic acid reversed inhibition caused by deoxyguanylic acid, but not that caused by deoxyadenylic acid. Thymidylic acid reversed inhibition caused by deoxyadenylic acid better than that caused by deoxyguanylic acid. Uridylic acid and cytidylic acid were no longer effective in reversing the inhibitions. This organism preferentially responded to monophosphorylated compounds as inhibitors and as reversers of inhibitions. Studies on the acid-soluble nucleotide pool revealed an accumulation of adenosine triphosphate, guanosine triphosphate, and an unidentified compound which resembled a nucleotide in its physical properties. These data cannot be explained by known metabolic pathways of nucleic acid biosynthesis. This organism responds differently from other related organisms to nucleic acid derivatives; therefore, it may be a new useful tool for studying nucleic acid metabolism and biosynthesis.

Journal Article↗
PubMedDate not supplied

Mycobacterium sp. as a possible cause of hypersensitivity pneumonitis in machine workers.

Hypersensitivity pneumonitis (HP) in workers exposed to metal removal fluids (MRFs) is increasing. This study supports the hypothesis that aerosolized mycobacteria colonizing the MRFs likely cause the disease. Three case studies of HP outbreaks among metal workers showed potentially high exposures to a rare and newly proposed Mycobacterium species. Retrospective review of samples submitted to our laboratory showed an association between presence of mycobacteria and HP.

Alveolitis, Extrinsic Allergic↗