PubMed · 11432081
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C Simpson, A M Pheley. 2001. Without sampling information, data lack impact.. https://pubmed.ncbi.nlm.nih.gov/11432081/
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Three major foodborne outbreaks of salmonellosis in 1998 and 1999 were linked to the consumption of raw alfalfa sprouts. In this report, an improved method is described for isolation of Salmonella from alfalfa seed lots, which had been implicated in these outbreaks. From each seed lot, eight samples each containing 25 g of seed were tested for the presence of Salmonella by the US FDA Bacteriological Analytical Manual (BAM) procedure and by a modified method applying two successive pre-enrichment steps. Depending on the seed lot, one to four out of eight samples tested positive for Salmonella by the standard procedure and two to seven out of eight samples tested positive by the modified method. Thus, the use of two consecutive pre-enrichment steps led to a higher detection rate than a single pre-enrichment step. This result indirectly suggested that Salmonella cells on contaminated seeds might be injured and failed to fully resuscitate in pre-enrichment broth containing seed components during the first 24 h of incubation. Responses of heat-injured Salmonella cells grown in buffered peptone water (BPW) and in three alfalfa seed homogenates were investigated. For preparation of seed homogenates, 25 g of seeds were homogenized in 200 ml of BPW using a laboratory Stomacher and subsequently held at 37 degrees C for 24 h prior to centrifugation and filtration. While untreated cells grew at about the same rate in BPW and in seed homogenates, heat-injured cells (52 degrees C, 10 min) required approximately 0.5 to 4.0 h longer to resuscitate in seed homogenates than in BPW. This result suggests that the alfalfa seed components or fermented metabolites from native bacteria hinder the repair and growth of heat-injured cells. This study also shows that an additional pre-enrichment step increases the frequency of isolation of Salmonella from naturally contaminated seeds, possibly by alleviating the toxic effect of seed homogenates on repair or growth of injured cells.
In the present study, gastric juice resistant tablet formulations of lactic acid bacteria (LAB) were developed, using hydroxypropylmethylcellulose acetate succinate (HPMCAS) as well as alginates, apple pectin and Metolose as matrix forming components. To optimize the formulation-using survival rate in acid medium, and disintegration time in intestinal fluid as test parameters-tablets were modified with respect to LAB content, amount of applied excipients per tablet, and compaction forces. A decrease of viable cells of not more than one log unit after 2h of incubation in acid medium was desired, as well as a disintegration time of 1h in phosphate buffer pH 6.8. It was found that the amount of HPMCAS in the tablet correlates with gastric juice resistance. As HPMCAS also leads to a decrease of disintegration time in intestinal fluid, slight amounts of this excipient were preferred. The best protective qualities against artificial gastric juice were observed when tablets were prepared from compaction mixtures of LAB, HPMCAS and sodium alginate.
BACKGROUND AND OBJECTIVES: To investigate the bactericidal effect of an 809 nm semiconductor laser alone, and in combination with NaOCl/H(2)O(2) irrigation in root canals in vitro. STUDY DESIGN/MATERIALS AND METHODS: A total of 72 human single-rooted teeth extracted for periodontal reasons were included. The crowns were removed, the roots shortened to a length of 12 mm, and the canals enlarged up to an apical size of #50 file. The specimens were autoclaved and incubated with a suspension of Streptococcus sanguinis (ATCC 10556). Laser irradiation was performed on a PC-controlled XY translation stage. A 200 micron optic fiber was used. Twelve specimens were irradiated at a power output of 1.5, 3.0, and 4.5 W in the cw-mode. The total irradiation time was 60 seconds per canal. Twelve specimens were rinsed with NaOCl and H(2)O(2) only, 12 were rinsed and laser treated, and 12 served as untreated controls. After laser treatment, the specimens were sonicated and the bacterial growth was examined by counting colony forming units on blood agar plates. Temperature changes at the outer root surface during irradiation were registered by means of thermocouples. Treated and control specimens were investigated by means of scanning electron microscopy. RESULTS: Mean bacterial reductions of 0.35 log steps at a power output of 1.5 W, 1.44 at 3.0 W, and 2.84 at 4.5 W were calculated. Bacterial reduction by the NaOCl/H(2)O(2) solution alone was 1.48 and comparable to that achieved by irradiation at 3.0 W. With a log kill 2.85, the combination of rinsing and laser irradiation at 3.0 W resulted in a further significant bacterial reduction as compared to rinsing alone (P = 0.004). Irradiation did not result in excessive heat generation at the root surface. Carbonization of the root canal wall was observed in single teeth at 3.0 and 4.5 W and no controlled sealing of the dentinal tubules could be achieved in the root canal. CONCLUSIONS: The application of the diode laser might be an adjunct to conventional endodontic treatment when used in combination with a NaOCl/H(2)O(2) solution.