Excretion of ␣-keto acids by clinical isolates and laboratory strains of Salmonella typhimurium was determined by high-performance liquid chromatography analysis of culture supernatants. The levels of excretion increased markedly with increasing iron stress imposed by the presence of ␣,␣-dipyridyl or conalbumin in the medium. The major product was pyruvic acid, but significant concentrations of ␣-ketoglutaric acid, ␣-ketoisovaleric acid, and ␣-ketoisocaproic acid were also observed. Maximal excretion occurred at iron stress levels that initially inhibited bacterial growth; the concentration of ␣,␣-dipyridyl at which this was observed differed between strains depending on their ability to secrete and utilize siderophores, suggesting that the intracellular iron status was important in determining ␣-keto acid excretion. However, prolonged incubation of the siderophore-deficient S. typhimurium strain enb-7 under conditions of high iron stress resulted in significant delayed bacterial growth, promoted by tonB-dependent uptake of iron complexed with the high accumulated levels of pyruvic acid and other ␣-keto acids. Strain RB181, a fur derivative of enb-7, excreted massive amounts of ␣-keto acids into the culture medium even in the absence of any iron chelators (the concentration of pyruvic acid, for example, was >25 mM). Moreover, RB181 was able to grow and excrete ␣-keto acids in the presence of ␣,␣-dipyridyl at concentrations threefold greater than that which inhibited the growth of enb-7.

The monosaccharide composition of the LPS from 5 Campylobacter jejuni strains and 7 Campylobacter coli strains has been studied. All LPS's contained KDO, heptose, glucosamine, glucose, and (with one exception) galactose. All C. jejuni and 3 C. coli LPS's contained greater than 1% galactosamine. 3-Amino-3.6-dideoxyglucose was present in all but one C. coli LPS and in only one C. jejuni LPS.

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SUMMARYEighty-nine Salmonella enteritidis phage type 25/17 strains isolated from a localized outbreak in the German state Nordrhein-Westfalen (outbreak NWI) could not be further differentiated by biochemotyping and plasmid pattern analysis. They were submitted to a complex typing system consisting of modern physico-chemical analytical procedures. In lipopolysaccharide pattern analysis the strains proved to be homogeneous. In multilocus enzyme electrophoresis, outer membrane and whole cell protein pattern (WCPP) analysis, and Fouriertransform infrared (FT-IR) spectroscopy (increasing extent of differentiation in the given order) strains deviating from each basal pattern were found. The extent of correspondence in these deviations was satisfactory.Forty-six strains of the same sero-and phage type, however, obtained from different outbreaks, were additionally typed. The results obtained with them indicate that the data of the first group were not restricted to strains from outbreak NWI, but of general validity.It was found that both WCPP and FT-IR represent valuable methods for the sub-grouping of bacteria.