Effect of acetylation on arthropathic activity of group A streptococcal peptidoglycan-polysaccharide fragments.

Purified group A streptococcal peptidoglycan-polysaccharide (PG-PS) fragments were either de-O-acylated, or acetylated and then de-O-acylated to yield N-acetylated PG-PS. Native PG-PS was poorly degraded, N-acetylated PG-PS was extensively degraded, and de-O-acylated PG-PS was only slightly degraded by hen egg white lysozyme. N-acetylated PG-PS was also extensively degraded by human lysozyme and partially degraded by rat serum or rat liver extract. After a single intraperitoneal injection of rats with a sterile, aqueous suspension, all PG-PS preparations induced acute arthritis. The acute arthritis induced by N-acetylated PG-PS was significantly more severe than that induced by native PG-PS; that induced by de-O-acylated PG-PS was of intermediate severity. After the acute reaction, rats injected with native PG-PS developed chronic relapsing erosive synovitis which remained severe for the duration of the experiment (83 days). In contrast, joint inflammation induced by N-acetylated PG-PS resolved within 6 weeks with little evidence of recurrent disease. Chronic arthritis induced by de-O-acylated PG-PS was of intermediate severity. In another assay of arthropathic activity, the arthritis in all rat ankle joints, which had been injected directly with native PG-PS, could be reactivated 3 weeks later by the intravenous injection of a small dose of PG. In contrast, only 50% of the joints initially injected with de-O-acylated PG-PS and none of the joints injected with N-acetylated PG-PS could be reactivated. These studies support the concepts that the resistance of PG-PS to muralytic digestion is crucial for chronic arthropathic activity and that the nature and degree of PG acetylation are important molecular determinants of the phlogistic activities of PG-PS polymers.

Substrate degradation and pressure tolerance of free-living and attached bacterial populations in the intestines of shallow-water fish.

Bacterial populations attached to intestinal linings of shallow-water fish were compared to those free in the lumen for response to hydrostatic pressure and ability to degrade a variety of substrates. Results suggested that, unlike reports on gut-associated deep-sea bacteria, the two shallow-water populations were not significantly different in their pressure or substrate responsiveness.

Distribution of Vibrio vulnificus and other lactose-fermenting vibrios in the marine environment.

During the summer of 1981, 3,887 sucrose-negative vibrios were isolated from seawater, sediment, plankton, and animal samples taken from 80 sites from Miami, Fla., to Portland, Maine. Of these, 4.2% were able to ferment lactose. The lactose-positive strains isolated from the various samples correlated positively with pH and turbidity of the water, vibrios in the sediment and oysters, and total bacterial counts in oysters. Negative correlations were obtained for water salinity. Numerical taxonomy was performed on 95 of the lactose-fermenting environmental isolates and 23 reference strains. Five clusters resulted, with the major cluster containing 33 of the environmental isolates and all of the Vibrio vulnificus reference strains. The 33 isolates, which produced an acid reaction in lactose broth within hours of initial inoculation, represented 20% of all lactose-fermenting vibrios studied. These isolates were nearly identical phenotypically to clinical strains of V. vulnificus studied by the Centers for Disease Control, Atlanta, Ga., and by our laboratory, and their identification was confirmed by DNA-DNA hybridization studies. V. vulnificus was isolated from all sample types and from Miami to Cape Cod, Mass., and comparison of the environmental parameters of the eight subsites yielding this species with those of all 80 subsites revealed no significant differences. The majority of the isolates were obtained from animals, with clams providing most (84%) of these. On injection into mice, 82% of the V. vulnificus isolates resulted in death. Members of the remaining four clusters contained strains which differed from V. vulnificus in such phenotypic traits as luminescence and in urease or H(2)S production. None of the other reference cultures, including nine other Vibrio species, were contained in the remaining clusters, and these isolates could not be identified. Most of these were also lethal for mice. Phenotypic differences, potential pathogenicity, and geographic distribution of the five clusters were examined. It is concluded that V. vulnificus is a ubiquitous organism, both geographically and in a variety of environmental sources, although it occurs in relatively low numbers. The public health significance of this organism and of the other unidentified lactose-fermenting Vibrio species is discussed.

Distribution and ecology of Vibrio vulnificus and other lactose-fermenting marine vibrios in coastal waters of the southeastern United States.

Water, sediment, plankton, and animal samples from five coastal sites from North Carolina to Georgia were sampled for their lactose-fermenting vibrio populations. Over 20% of all vibrios tested were sucrose negative and o-nitrophenyl-beta-D-galactopyranoside (ONPG) positive, suggesting identification as the human pathogen Vibrio vulnificus. These vibrios were isolated from all sample sites and sources (water, sediment, plankton, and animals). Correlations with several of 19 environmental parameters monitored at each site were found for total vibrios. The presence of ONPG-positive, sucrose-negative vibrios was correlated with hydrocarbon levels in the water and, in the case of plankton samples, with salinity. A total of 279 sucrose-negative, ONPG-positive isolates were subjected to numerical taxonomic analysis, which resulted in three major clusters. Cluster I corresponded to and included 11 reference strains of V. vulnificus. Cluster II contained the largest number (133) of isolates, of which the great majority were bioluminescent. Although having a resemblance to V. harveyi, the isolates were ONPG positive and many were H2S positive. Cluster III consisted of strains similar to the group F vibrios (V. fluvialis). Of all of the isolates, 55% were luminescent, of which over 20% were lethal when injected into mice. Problems involved in detecting lactose fermentation among marine vibrios and the potential pathogenicity of these organisms are discussed.