Typing of Salmonella enterica subsp. enterica serovar Mbandaka isolates.

Recently, Salmonella enterica subsp. enterica serovar Mbandaka (S. Mbandaka) has gained some importance in the epidemiology of salmonellosis in Poland. Since biotyping, resistance typing, and plasmid profiling were insufficient for strain differentiation, genome macrorestriction by means of pulse-field gel electrophoresis (PFGE) was applied and proved to be the method of choice in S. Mbandaka epidemiological studies. XbaI and BcuI macrorestriction produced 15 and 14 pulse-field profiles (PFP), respectively, but in the case of each enzyme one profile was prevalent. When macrorestriction profiles were combined, a total 24 patterns were found. Based on the similarity of the profiles, four clonal lineages were identified. One clonal lineage contained the majority of poultry, feed and human isolates. Poultry was concluded to be an important source of S. Mbandaka for humans in Poland. Complementary use of various typing techniques improved efficacy of epidemiological studies giving possibility to subdivide S. Mbandaka into 35 types and the index of discrimination reached 0.947.

Prevention of Salmonella typhimurium caecal colonisation by different preparations for competitive exclusion.

The number of Salmonella typhimurium per gram of caecal contents of chicks, given orally prior to infection with different preparations containing protective intestinal flora, was significantly lower than in the control group. The best results were obtained when the lyophilised caecal rinses were given orally to 1-day-old chicks. Less effective methods of protection of the alimentary tract proved to be oral application to chicks of fresh faeces or lyophilised faeces and administration of the lyophilised caecal rinses with drinking water. Oral application of undefined anaerobic caecal culture to chicks proved to be the least effective of the methods investigated of protecting them against Salmonella colonisation, although even these results differed statistically from those of the controls. The percentage of infected birds 7 days after challenge confirmed the efficacy of oral application of lyophilised caecal rinses--only 30% of individuals from the group treated in this way proved to be Salmonella positive. In contrast, the percentage of infected birds in other experimental groups ranged from 50% to 75% and was 100% in the controls.

Rapid detection and enumeration of Salmonella in chicken carcass rinses using filtration, enrichment and colony blot immunoassay.

A strategy was developed for 24-h detection and enumeration of Salmonella spp. on processed chicken carcasses. Carcasses were rinsed with saline and the rinses spiked with known numbers of serogroup B, C, D or E Salmonella. The total rinse volume was passed through two filter units of decreasing pore size. These removed most of the extraneous material while permitting rapid passage of more than 77% of the Salmonella. At least 100 ml of the filtrate was passed through a third filter unit containing a nitrocellulose capture membrane. Captured bacteria were selectively enriched by incubating the nitrocellulose membrane on filter pads soaked in Rappaport-Vassiliadis broth and then on pads soaked in brilliant green broth containing sulfadiazine and novobiocin. A colony blot immunoassay using two anti-Salmonella monoclonal antibodies was used to identify and enumerate the captured Salmonella. As few as five Salmonella colony forming units per carcass rinse could be detected. An evaluation of this system with 24 field samples indicated that the specificity was comparable to and the sensitivity higher than that of standard culture procedures.

Choice of the optimal method for the isolation of Salmonella from meat- and bone powder designed for industrial feed mixtures.

The purpose of this paper was (1) comparison of four multi-step methods used for Salmonella isolation from meat- and bone powder; (2) elaboration of a new sensitive method of Salmonella isolation from this product; (3) evaluation of a new solid selective medium (BxLH) described by the authors for Salmonella isolation in comparison to brilliant green agar (BGE) according to Edel and Kampelmacher. The study was carried out on 173 meat- and bone powder samples naturally contaminated with Salmonella oranienburg. The samples were examined for the Salmonella presence by means of four compared methods (Methods 1 to 4). The new method of isolation proposed by the authors (Method 3) proved to be the most effective among all compared for Salmonella recovery. It seems that the superiority of Method 3 in comparison to the other applied was a result of, (1) homogenization of the investigated samples in distilled water before preincubation followed by maintenance at room temperature for 2-4 h; (2) the use of a new selective BxLH agar; (3) the use of multiple plating after selective enrichment. The BxLH medium was shown to be more suitable for Salmonella isolation than BGE agar because of more efficient inhibition of other bacterial growth with simultaneously abundant growth of the Salmonella organisms. The additional advantage offered by BxLH agar was the fact that lactose-positive salmonellas grow as typical representatives of this genus. This enables their identification, in contrast to the situation when lactose containing media are used, where the colonies of such salmonellas are similar to the colonies of, for example, Escherichia coli.

Effect of copper and tri- and hexavalent chromium on the work of an activated sludge.

The effect of metals (Cu2+, Cr3+, Cr6+) on the work of an activated sludge grown in crude oil refining or synthetic wastes was examined. The activated sludge method was found to be applicable for the purification of wastes carrying up to 0.8 mgCu2+/1,15mgCr3+/1, or 20mgCr6+/1. Higher concentrations of these metals inhibited the work of the activated sludge which was evident in inferior purification and reduced intensity of respiration of the activated sludge microorganisms.