A simplified method has been devised for typing Pseudomonas aeruginosa by pyocin production. Pyocins are produced as strains grow overnight in Trypticase soy broth (without glucose) plus 1% potassium nitrate. Because P. aeruginosa can use nitrate instead of oxygen as a terminal electron acceptor, mechanical shaking is not necessary, nor is induction by mitomycin C. Pyocins can now be produced in screw-cap tubes in a water bath or incubator. A total of 250 strains were tested as possible pyocin indicators, which included 60 strains already used in pyocin-typing systems. The final set contained 18 indicators which were chosen because (i) they had clear positive or clear negative reactions, thus eliminating reactions difficult to read, (ii) they had few zones due to bacteriophage lysis, and (iii) they were most sensitive in differentiating clinical isolates of P. aeruginosa. The final typing method was tested in several studies and the results were clear; thus definitive epidemiological conclusions could be made. Because it is simple to perform and easily automated, the new method should have application in many hospitals; however, it should be used only in carefully planned epidemiological studies. The method and its application are described in detail, and some pitfalls are discussed. Nosocomial infections caused by Pseudomonas aeruginosa continue to be a problem in many hospitals (3, 5, 8, 12, 16, 23). Within any institution there can be hundreds of different strains because it is often found in the human gut, and because it can survive and multiply in moist environments of the hospital. In any epidemiological study, a sensitive technique is required to compare these numerous strains. A number of methods have been used to differentiate P. aeruginosa in epidemiological studies. These epidemiological markers include

We present a case of disseminated atypical mycobacterial (Mycobacterium intracellularis) infection of the urinary tract. The patient had anhydrous ectodermal dysplasia and an unrelated defect in cell-mediated immunity. The infection resulted in a lengthy ureteral stricture with resultant hydronephrosis and diminished kidney function. A review of the literature revealed only 13 previous cases of atypical mycobacterial infection of the urinary tract. It is important to distinguish between simple colonization by these organisms and actual infection. Differentiation between atypical mycobacterial infection and urinary tuberculosis is important in determining the therapeutic regimen.

Good yields of pyocin are obtained when Pseudomonas aeruginosa is grown in Trypticase soy broth (without glucose) (BBL) plus 1% potassium nitrate. As a result, pyocin production for routine epidemiological typing can be done in screw-cap tubes, without mechanical agitation or mitomycin C induction.

No abstract

A simplified method has been devised for typing Pseudomonas aeruginosa by pyocin production. Pyocins are produced as strains grow overnight in Trypticase soy broth (without glucose) plus 1% potassium nitrate. Because P. aeruginosa can use nitrate instead of oxygen as a terminal electron acceptor, mechanical shaking is not necessary, nor is induction by mitomycin C. Pyocins can now be produced in screw-cap tubes in a water bath or incubator. A total of 250 strains were tested as possible pyocin indicators, which included 60 strains already used in pyocin-typing systems. The final set contained 18 indicators which were chosen because (i) they had clear positive or clear negative reactions, thus eliminating reactions difficult to read, (ii) they had few zones due to bacteriophage lysis, and (iii) they were most sensitive in differentiating clinical isolates of P. aeruginosa . The final typing method was tested in several studies and the results were clear; thus definitive epidemiological conclusions could be made. Because it is simple to perform and easily automated, the new method should have application in many hospitals; however, it should be used only in carefully planned epidemiological studies. The method and its application are described in detail, and some pitfalls are discussed.