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Biomedical subjects

H Lior

Publications and source records attributed to H Lior.

At least 109 records · Page 6Linked to original sources
PubMed1983

The epidemic spread of Salmonella typhimurium phage type 10 in Canada (1970-1979).

The frequency of Salmonella typhimurium phage type 10 across Canada was monitored during the period 1970-1979. Phage type 10 isolations increased from 1.2% in 1970 to 68.8% in 1979 among isolates from human sources and from 1.5 to 30.6% in isolates from nonhuman sources. Examination of food-poisoning outbreaks and a study of the animal-host associations of phage type 10 revealed that contaminated poultry products appear to be the most common sources of human infections. The majority (89.3%) of S. typhimurium phage type 10 strains were sensitive to antibiotics. Of the resistant strains, 73.3% were resistant to single antibiotics and 26.7% were multiresistant. Thirty-three different patterns of antibiotic resistance were observed. A number of the resistance determinants were transferable by conjugation and the R plasmids were found to belong to the incompatibility groups HI1, FII, N, I alpha, and C.

Animals↗
PubMed1982

Evaluation of two Salmonella typhimurium hybrids as challenge organisms in a system for the assay of typhoid vaccines.

A mouse-virulent Salmonella typhimurium hybrid (H42), which expresses the Salmonella typhi Vi antigen in addition to S. typhi O antigens 9 and 12, and a mouse-virulent S. typhimurium hybrid (H1), which expresses only the 9 and 12 antigens of S. typhi, were compared in their behavior as challenge organisms in a system developed to assay the protective capabilities of typhoid vaccines. Swiss-Webster white mice, vaccinated intraperitoneally with live Escherichia coli hybrids expressing the S. typhi O antigens 9 and 12, were significantly protected against death from intraperitoneal challenge with each of the S. typhimurium hybrid strains. Vaccination with an E. coli hybrid expressing the S. typhi Vi antigen in addition to O antigens 9 and 12 was seen to confer no advantage in protection against either S. typhimurium hybrid challenge organism over that obtained by vaccination with an E. coli hybrid expressing only the O antigens of S. typhi. However, a notable difference in the behavior of the two S. typhimurium hybrids was seen in mice vaccinated with the parent of the E. coli hybrid vaccinating strains, E. coli F464, which expresses no surface antigens common to either of these S. typhimurium hybrid challenge organisms. A nonspecific (with respect to the vaccinating strain) protective effect, believed to be associated with Vi antigen expression by the challenge organism, was seen against the challenge with S. typhimurium hybrid H42 after F464 vaccination, whereas no protection was conferred by F464 vaccination against the challenge with Vi-nonexpressing S. typhimurium hybrid H1. Inasmuch as neither S. typhimurium hybrid discriminates between the expression or nonexpression of the Vi antigen in a vaccinating strain, it is concluded that the Vi-nonexpressing S. typhimurium hybrid H1, which more clearly indicates the vaccine-specific protective role of the S. typhi O antigens and does not exhibit the nonspecific protection response of hybrid H42, is the better choice as challenge organism for this vaccine assay system.

Animals↗
PubMed1982

Serotyping of Campylobacter jejuni by slide agglutination based on heat-labile antigenic factors.

A serotyping scheme for Campylobacter jejuni was developed based on slide agglutination of live bacteria with whole cell antisera absorbed with homologous heated and heterologous unheated cross-reactive antigens. Among 815 isolates from human and nonhuman sources, 21 serogroups were recognized. Of the 615 isolates from human cases of gastroenteritis, 529 (86%) were typable; 455 strains agglutinated in 20 single antisera, whereas 74 isolates agglutinated in various pairs of antisera, allowing subdivision of some main serogroups into subserogroups. Of the 200 isolates of C. jejuni from nonhuman sources (chicken, swine, etc.), 166 (83%) were typable, 145 cultures agglutinated in various single antisera, and 21 strains agglutinated with different pairs of antisera. Among isolates from all sources, 8 serogroups (1, 2, 4, 5, 7, 8, 9, and 11) were encountered most frequently. Serogroups 1, 2, 4, 5, 7, 9, and 11 were most common among human isolates; the majority of the chicken and all of the swine isolates belonged to the same serogroups identified from human cases. Very good serological correlation was obtained in 20 family outbreaks and 4 community outbreaks.

Agglutination Tests↗
PubMed1982

The relationships of salmonellae from infected broiler flocks, transport crates or processing plants to contamination of eviscerated carcases.

Three flocks raised for broiler or roaster performance tests were studied to determine the incidence and sources of salmonellae during the growing period, transport and processing and to relate these to contamination of processed carcasses. Day old chicks in two of the tests, (tests IV and V), were treated with a culture of intestinal anaerobes derived from mature chickens. The incidence of salmonellae during the growing period was too low to permit any conclusions about the efficacy of this culture in preventing Salmonella infection, but it had no adverse effect on flock performance. Carcasses from all three flocks were contaminated with salmonellae. Although the test IV flock was raised free of salmonellae, 46% of the carcasses tested from this flock were contaminated. The apparent source was the transport crates, 99% of which yielded salmonellae before the flock was loaded. In test V, 92% of the carcasses tested yielded salmonellae. The apparent sources were: flock infection (apparently originating from the parent flock), contaminated crates, spread during transport, and plant contamination. The flock of test VI was infected with Salmonella albany, and 54% of the carcasses tested were contaminated with this serovar. Carcasses of chicks infected early in life were more likely to be contaminated than those of chickens which contacted salmonellae later in the growing period.

Abattoirs↗
PubMed1981

Antibiotic resistance and R-plasmids in food chain Salmonella: evidence of plasmid relatedness.

A large number of strains (1,783) belonging to 15 Salmonella serovars isolated, in Canada, from the three major links of the human food chain were screened for multiple antibiotic resistance and the presence of R-plasmids. Multiresistant strains occurred among animal feed, livestock, and human isolates at frequencies of 4, 22, and 14%, respectively. Conjugation analysis revealed that 58% of the isolates from feeds, 87% of those from livestock, and 89% of the human strains carried all or part of their resistance determinants extrachromosomally on R-plasmids. Conjugative plasmids representing nine different incompatibility groups were detected, with the Inc I alpha group being predominant. Within the limits of the parameters measured, certain of these plasmids show a degree of relatedness suggestive of a common ancestry.

Anti-Bacterial Agents↗
PubMed1981

Hemolysin and K antigens in relation to serotype and hemagglutination type of Escherichia coli isolated from extraintestinal infections.

Escherichia coli isolated from cases of bacteremia and from a variety of urinary tract infections were characterized according to serotype (O:H antigenicity), K type (possession of K1, K2, K3, K12, or K13), hemagglutination (HA) type, and production of beta-hemolysin. Results obtained with the bacteremia and urinary tract infection isolates were similar except for more hemolytic isolated from urine than from blood (42 versus 29%) and more K1+ isolates from blood than from urine (50 versus 29%). A close correlation was found between Ha type VI (production of fimbriae which mediate mannose-resistant HA of human and African green monkey erythrocytes) and the production of hemolysin or K1 capsular antigen or both. Most (95 of 98, or 95%) of the HA type VI+ blood isolates and most (146 of 164, or 89%) of the HA type VI+ urine isolates produced hemolysin or K1 or both, in contrast to 22 and 26%, respectively, of those belonging to HA types other than HA type VI. Also, 76% of all hemolytic and 70% of all K1+ isolates belonged to HA type VI. Remarkably few of the HA type VI+ isolates (13%) and even fewer of the HA type VI- isolates (3%) produced both K1 and hemolysin; these belonged mainly to serotypes O16:H6, O18:H7 and O2:H4. Other major serogroups were usually K1+/hemolysin- (O1, O7) or K1-/hemolysin+ (O2, O4, O6). At least 74% (262 of 351) and possibly as many as 83% (293 of 351) of those isolates which produced mannose-resistant HA of human erythrocytes were classified as HA type VI+; 31 isolates produced mannose-resistant HA with all erythrocytes tested. Taking serogroup and serotype into consideration, we conclude that the E. coli fimbrial hemagglutinin(s) responsible for the HA type VI phenotype will prove to be the same as the virulence-associated mannose-resistant adhesins of uropathogenic E. coli which other investigators have characterized as unique fimbrial antigens detectable by mannose-resistant HA of human erythrocytes.

Antigens, Bacterial↗
PubMed1981

Importation of salmonellae with aquarium species.

An examination of shipments of aquarium species arriving in Canada over a 2-year period revealed that one-third of the shipments of aquarium snails and aquarium frogs were contaminated with Salmonella. Salmonella were also isolated from a shipment of aquarium newts but were not recovered from goldfish. Included among these salmonellae were four of the serovars most commonly associated with human salmonellosis in Canada. Several unusual salmonellae were also isolated including a Salmonella florida that produced a delayed, weakly positive o-nitrophenyl-beta-D-galactosidase reaction, and a bacteriophage 14 lysogenized Salmonella mbandaka. The association of salmonellae with aquarium species is clearly adding to the pool of this human pathogen in Canada, and may contribute to human infections.

Animals↗
PubMed1981

Cytotoxicity and suckling mouse reactivity of Aeromonas hydrophila isolated from human sources.

Human isolates of Aeromonas hydrophila and Plesiomonas shigelloides were tested for their ability to produce cytotoxins and (or) enterotoxins. The incidence of cytotoxin production by A. hydrophila was 81% for isolates from stool and 44% for extraintestinal isolates. Chinese hamster ovary (CHO) cells were more sensitive to A. hydrophila cytotoxin than either Vero or Y-1 mouse adrenal tumor cells (y-1). There was no evidence of cytotonic enterotoxin production by any of the isolates tested. Cytotoxin-containing filtrates from A. hydrophila were found to provoke a positive reaction in suckling mice. The response in mice was heat labile, and data supporting correlation of this activity with the cytotoxin produced by these organisms are presented. Following concentration, cytotoxin and material reactive in suckling mice were found to coelute from Sephadex G-25 and dose-response was demonstrated in mice. Antitoxin prepared to this material effectively neutralized cytotoxin, mouse reactivity, and rabbit ileal loop response. No evidence was obtained for either cytotoxin or enterotoxin production by P. shigelloides strains tested in this study.

Adrenal Gland Neoplasms↗
PubMed1980

Flock infection and transport as sources of salmonellae in broiler chickens and carcasses.

Cultural monitoring was used to determine the incidence and sources of salmonellae in a 4160-bird broiler flock raised on litter in 32 pens. Twenty-five of the pens remained apparently free of salmonellae during the 49-day growing period. Salmonella johannesburg, first detected in the meat meal component of the starter ration, was recovered from the litter of seven pens and from the intestines of dead or culled chicks from two pens. Salmonella alachua was also recovered from two of these pens. Culture of swabs collected from the plastic crates used to transport this flock for processing showed that 97/112 (86.6%) were contaminated with salmonellae (15 serovars) before the birds were loaded. The crate washer at the plant did not remove salmonellae from these crates: 97/132 (73.5%) crates sampled after washing yielded salmonellae. Eleven serovar were recovered, including S. johannesburg and S. alachua introduced by the infected flock. Twelve of 31 chickens (38.7%) collected when the birds were unloaded at the processing plant were intestinal carriers of S. johannesburg and/or S. alachua and 29 (93.5%) were external carriers. Salmonella johannesburg, S. alachua and four other serovars were isolated from the feathers of these birds. Eleven of 25 (44%) carcasses tested from this flock yielded salmonellae. Salmonella johannesburg or S. alachua, first isolated from the infected flock, were recovered from five carcasses and S. haardt and S. Typhimurium, first isolated from the transport crates were recovered from six carcasses.

Animals↗
PubMed1980

Distribution of phagovars of Salmonella typhimurium in Canada (1969-1976).

The distribution of Salmonella typhimurium phagovars in Canada during the period 1969-1976 is described. Of 9282 strains examined, 69.6% were of human origin and the remaining 30.4% were isolated from non-human sources. The typable strains of all sources, constituted 73.1% of all strains examined, and were representative of 107 different phagovars. There were only 15 phagovars accounting for more than 1% of the cases either from human or non-human sources. Phagovar 49 consistently showed the highest incidence in both groups (human 25.2% and non-human 19.9%). Although 26.6% of the strains from all sources were not typable, the use of experimental phages M 499 and 721 reduced the percentage of untypable strains to 9.9%. Yearly data on the incidence of phagovars from human sources showed a gradual decrease of phagovar 49 and an increase of phagovar 10. Examination of 358 human outbreaks of S. typhimurium revealed 47 different phagovars during the 8-year period.

Animals↗
PubMed1980

Sources of salmonellae in an uninfected commercially-processed broiler flock.

Cultural monitoring was used to study the incidence and sources of salmonellae in a 4160 bird broiler flock during the growing period, transport and processing in a commercial plant. No salmonellae were isolated from any of 132 litter samples of 189 chickens cultured during the seven-week growing period, even though nest litter samples from four of the eight parent flocks yielded salmonellae and Salmonella worthington was isolated from the meat meal component of the grower ration. On arrival at the plant, 2/23 birds sampled carried S. infantis on their feathers, although intestinal cultures failed to yield salmonellae. Three of 18 processed carcasses samples yielded salmonellae (S. infantis, S. heidelberg, S. typhimurium var copenhagen). The most likely source of these salmonellae was the plastic transport crates, since 15/107 sampled before the birds were loaded yielded salmonellae (S. infantis, S. typhimurium). The crate washer at the plant did not reduce the incidence of Salmonella-contaminated crates, since 16/116 sampled after washing yielded salmonellae (S. infantis, S. typhimurium, S. heidelberg, S. schwarzengrund, S. albany).

Animals↗
PubMed1979

Mouse protective capabilities of Escherichia coli hybrids expressing Salmonella typhi antigens.

An Escherichia coli hybrid, F1061, expressing Salmonella typhi somatic antigens 9 and 12, and a derivative of this hybrid, E. coli hybrid WR3078, expressing the S. typhi Vi antigen in addition to somatic antigens 9 and 12, were compared with S. typhi Ty2 in experiments to test their ability, as live vaccines, to protect Swiss white mice against death from challenge with a mouse-virulent Salmonella typhimurium hybrid expressing the S. typhi antigens 9, 12, Vi, and d. When the live, vaccinating organisms were administered intraperitoneally, 87.5% of the mice immunized with S. typhi Ty2 survived challenge, as compared with 62.5% of those immunized with E. coli hybrid F1061 and 55% of those inoculated with E. coli hybrid WR3078. When live organisms were administered orally at a dose of 10(9), 67.5% of the mice immunized with S. typhi Ty2 survived challenge as compared with 47.5% of those immunized with E. coli hybrid F1061 and 40% of those administered E. coli hybrid WR3078. Thus, the protection conferred by E. coli hybrid F1061 expressing only the S. typhi somatic antigens, although significant in this system, was inferior to that conferred by S. typhi Ty2 and the addition of the S. typhi Vi antigen to this hybrid (creating E. coli hybrid WR3078) did not enhance that protection.

Administration, Oral↗
PubMed1978

Isolation of bacteriophage 14-lysogenized Salmonella from the freshwater aquarium snail Apullaria.

A naturally occurring Salmonella mikawasima serologically converted by phage 14 (6,7,14:y:e,n,z15) has been isolated for the first time. An S. tennessee variant seroconverted by phage 14 (6,7,14:z29:-) was also isolated. The source of these salmonellae was the common freshwater aquarium snail Ampullaria. Phage 14 prepared from these serovariants was lytic for S. bovis-morbificans (6,8:r:1,5) and for S. hadar (6,8:z10:e,n,x).

Animals↗
PubMed1978

Heat-stable enterotoxin from Escherichia coli: factors involved in growth and toxin production.

Six enterotoxigenic strains of Escherichia coli produced variable levels of heat-stable enterotoxin (ST) when grown under pH control at 8.5 in a simple synthetic medium containing neither amino acids nor vitamins. Bacterial growth and ST production were at levels as high as or higher than those observed in complex media. ST elaboration was detectable in the early logarithmic phase of growth and appeared to be related to disappearance of glucose in the growth medium. The results of this study did not suggest pH-dependent release of ST. Imposition of pH control in complex media resulted in increased growth rates, earlier detectable ST synthesis, and elevated levels of ST. In synthetic medium, attainment of the stationary growth phase was followed by a significant decrease in culture density and a concomitant increase in ST. Cellular autolysis experiments revealed that as much as 20% of the total ST activity was present in a cell-associated form.

Bacteriolysis↗
PubMed1978

Antibiotic resistance among predominant Salmonella serovars and phagovars in Canada.

The antibiotic susceptibility of 2609 Salmonella isolates, collected during the period 1975-1976, was tested and the relationships between antibiotic-resistance pattern, source of isolation, and serovar and phagovar were determined. Of 95 serovars examined, 40 were sensitive to all of the antibiotics tested. Salmonella typhimurium was the major contributor to multiple resistance from both human and non-human sources. Multiply resistant strains were not found from animal feed sources and, in addition, S. typhimurium, one of the most predominant serovars, was found in every source but animal feeds. 90% of phagovar 10 was sensitive to all antibiotics tested whereas over 80% of phagovars 3-aerogenic, 92, and 123 were multiply resistant.

Animals↗
PubMed1977

Small pet aquarium frogs as a source of Salmonella.

Salmonellae were isolated from 21% of the samples of freshwater aquarium frogs tested and from 25% of the samples of aquarium water containing these frogs. The salmonellae were Salmonella arizonae, S. bovis-morbificans, S. hadar, S. saint-paul, S. typhimurium, and S. worthington. These isolations were made over a period of 9 months and from three different cities. This association of salmonellae with frogs may contribute to cases of human salmonellosis since other aquarium species have already been shown to contribute to such cases.

Animals↗