Use of a specific bacteriophage treatment to reduce Salmonella in poultry products.

Bacteriophages represent a group of viruses that specifically infect and replicate in bacteria and could potentially be used to reduce recovery of Salmonella from poultry carcasses. Bacteriophages were isolated from municipal wastewater in the presence of Salmonella enteritidis phage type 13A (SE). In the first 2 experiments, commercially processed broiler carcass rinse water was pooled and divided. The addition of 10(10) pfu/mL of a single bacteriophage (PHL 4) with selected concentrations of SE reduced (P < 0.05) frequency of SE recovered as compared with the control rinse water sample. In experiments 3 and 4, broiler carcasses were intentionally inoculated with SE, sprayed with selected concentrations of PHL 4, and rinsed for SE enrichment and isolation. Application of 5.5 mL of 10(8) or 10(10) pfu/mL of PHL 4 reduced (P < 0.05) the frequency of SE recovery as compared with controls. In experiments 5 and 6, commercially processed turkeys were rinsed with water containing 72 wild-type bacteriophages isolated against SE, which were amplified in SE, or the Salmonella isolated antemortem from drag swabs from the flock selected for in-plant treatment, or a combination of bacteriophages amplified by each bacterial host. All bacteriophage treatments reduced (P < 0.05) frequency of Salmonella recovery as compared with controls. Sufficient concentrations of an appropriate bacteriophage, or a bacteriophage mixture, can significantly reduce recoverable Salmonella from carcass rinses.

Immunophenotyping of acute leukemia by flow cytometric analysis. Use of CD45 and right-angle light scatter to gate on leukemic blasts in three-color analysis.

This article describes a procedure for performing routine three-color flow cytometric analysis for acute leukemia on lysed whole bone marrow preparations. This technique uses the combination of CD45 intensity and right-angle light scatter (RALS) to distinguish leukemic cells from normal lymphocytes, monocytes, neutrophils, eosinophils, and nucleated red blood cells. On this display, leukemic cells occupy a unique blast region characterized by intermediate CD45 density and low RALS, which, in normal marrows, contains less than 5% of the total cells. This approach was applied to 39 cases of acute leukemia and 8 cases of myelodysplasia or myeloproliferative disorders. The estimate of blasts by flow cytometric analysis was correlated highly with morphologic leukemic cell counts over a wide range. Moreover, the pattern seen on the CD45-RALS display was different for different French-American-British subtypes of leukemia, suggesting that this pattern might be useful for categorization. When CD45-peridin chlorophyll alpha protein was combined with other pairs of fluorescein isothiocyanate- and phycoerythrin-conjugated reagents, it was possible to set an analysis window on the leukemic blasts and display dual-parameter (ie, green vs. red fluorescence) data regarding expression of two additional markers on the leukemic population. This gating strategy was superior to traditional forward-angle versus RALS displays in that it did a better job of isolating the leukemic cells analytically.

Evaluation of the B-D urine culture kit.

Split samples of urine transported to the laboratory at 5 degrees C and in a boric acid-glycerol-sodium formate preservative (B-D Urine Culture Kit; Becton, Dickinson & Co.) were cultured immediately and, in the case of preserved urine, after 24 and 48 h of storage at 25 degrees C. Agreement between the results for cultures of specimens originally yielding greater than 10(5) colony-forming units (CFU) per ml and the results for urine preserved for 24 and 48 h was 85 and 71%, respectively. One-third of the specimens originally yielding 10(4) to 10(5) CFU per ml yielded less than 10(4) CFU per ml after 24 h of storage in preservative. Provided greater than 10(4) CFU per ml in specimens preserved for up to 24 h is regarded as equivalent to greater than 10(5) CFU per ml in original urine specimens, agreement of results was greater than 90%.

Contamination of cultures processed with the isolator lysis-centrifugation blood culture tube.

Overall contamination (on- plus off-streak) of the Isolator (Du Pont Co.) blood culture tube (23%) was greater than that of a conventional broth blood culture bottle (0.6%) or that of a biphasic blood culture bottle (1.3%). To determine the source of this contamination, Isolator cultures of blood from 59 healthy volunteers and of sterile broth from 60 vials were made. A total of 37% of the blood cultures and 22% of the broth cultures were contaminated (P = 0.06). Staphylococcus epidermidis-contaminated cultures represented 31 and 10% of the blood and broth cultures, respectively (P = 0.06). Contamination of plates processed on a bench top, in front of horizontal laminar flow, and in a biological safety cabinet with vertical laminar flow were compared. Processing plates in a biological safety cabinet resulted in a significant reduction in the number of contaminated plates (P less than 0.05). The contamination rate for 7,874 Isolator blood cultures processed in the biological safety cabinet was significantly decreased to 6.7% on-streak (9.3% on- plus off-streak). Contamination of Isolator-processed blood cultures originated from the laboratory and the patient. The former can be reduced by inoculating plates in a vertical laminar flow biological safety cabinet and by maintaining adequate quality control of media. The latter may be unavoidable.