A study of purified pyorubrin produced by local Pseudomonas aeruginosa.

A study of more than one thousand strains of local P. aeruginosa was performed. These include the strains production of various pigments, methods of extraction and purification, the pigments activity and characteristics. Lately, we have reported a comprehensive study about the purified blue pyocyanine pigment. This paper displays a parallel study of a number of physical and chemical properties of the purified pink pigment, the pyorubrin, that is produced by our local collection of P. aeruginosa strains. This characteristics is useful for production of an active pigment purpose and is necessary in the pigment use as antibiotic, in addition of importance in developing the methods of strains identification. Such studies are important due to the biological significance of pyorubrin activity against other bacteria and in comparison with some known antibiotics; stability tests and MIC (minimum inhibitory concentration) measurements indicate that found isolates were of animal and food origin mainly.

A study of purified pyocyanine produced by Pseudomonas aeruginosa: properties and grouping.

A study of more than one thousand strains of Pseudomonas aeruginosa was performed. These were collected from different sources, i.e. humans, animals, environment and food. Cumulative results revealed the existence of three different groups of pyocyanine. The biological importance of grouping this pigment is due to its activity against other bacteria in comparison with other antibiotics such as cyanomycin produced by Streptomyces cyanoflavus. No such grouping or any other classification was found in the literature. Stability test and MIC (minimum inhibitory concentration) measurements revealed the priority of group (I); also isolates of animal origin were found preferable. This may be due to the resistance of strains isolated from animals to antibiotics especially to carbenicillin and gentamycine. Observations indicate differences in optical properties of the blue pigment, i.e. absorption centres in the UV region. Some differences in their physical properties were also noted.

Kinetics of haemolytic activity in Proteus strains.

Proteus species produces toxins and constitutes a causative agent of some chronic and recurrent infections. For the study of haemolytic activity and the production and inhibition kinetics, a total of 140 local isolates were diagnosed and examined by the general biochemical methods, and their ability of haemolysis were tested by both direct and indirect methods utilizing the enrichment procedure for all strains. Two antibiotics, erythromycin and keflex (cephalexin), were tested for the study of haemolysis inhibition and its kinetisc. Rof further study, examples of Proteus species were selected; the new approach was based on mixing procedure between P. aeruginosa (also pyocyanine) and Proteus species for inhibition of haemolytic activity. Spectrophotometric analysis were used parallel to these studies to support quantitatively the observed results as all samples show an absorption centre at 542 +/- 1 nm. Results of such analysis of haemolytic activity and inhibition kinetics are presented.

Pyocyanin preparation from Pseudomonas aeruginosa isolated from heterogeneous clinical materials.

Pure pyocyanin was prepared from 120 strains of Pseudomonas aeruginosa isolated from different clinical specimens. The modified method used increased the purification 425-fold. The spectra of pyocyanin of all strains were found to be identical with a single major peak at 363 nm. The only difference between these spectra appeared to be the level value absorbance. Strains recovered from different clinical specimens differ in their ability for pigment production. The strains isolated from urine produced higher amounts of pyocyanin than other isolates.

In vitro pyocin activity of Pseudomonas aeruginosa strains pretreated with antibiotics.

Fifty-six selected strains of Pseudomonas aeruginosa belonging to 8 different pyocin types (H, I, 15, 6, PTI-1, PTI-2, PTI-3, PTI-4) were treated with subinhibitory concentrations (MIC/2) of either gentamicin or carbenicillin. Both treatments induced changes in pyocin patterns for all types but at different levels. The percentage of strains that retained their pyocin pattern were more or less equal in both treatments. In treated and untreated producers, the growth inhibition ability for 5 different strains of Enterobacteriaceae (Escherichia coli K12, E. coli EB, Proteus vulgaris, Salmonella typhi, Shigella flexneri) was also investigated. In all pyocin patterns the number of producers that inhibit the growth of these strains was lower after treatment with gentamicin or with carbenicillin, a smaller decrease was detected in the latter treatment. It appeared that the subinhibitory concentrations of these antibiotics are capable of protecting the Enterobacteriaceae strains from the action of the pyocins.