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At least 757 records · Page 42Linked to original sources
PubMed1969

Transferable drug resistance among Enterobacteriaceae isolated from cases of neonatal diarrhea in calves and piglets.

Fecal specimens were collected on 22 different Nebraska ranches and at the Department of Veterinary Science from young calves and pigs with neonatal diarrhea. Enterobacteriaceae isolated from these fecal specimens were screened for resistance to tetracycline, streptomycin, sulfamethizole, kanamycin, chloramphenicol, colistin, nitrofurantoin, and nalidixic acid. Of the 92 strains studied, 57 were resistant to one or more of these antimicrobial agents. Resistant strains were obtained from all herds involved in the study. The two most common resistance patterns were tetracycline streptomycin sulfamethizole (22 of 57) and tetracycline (13 of 57). None of the strains were resistant to chloramphenicol, colistin, nitrofurantoin, or nalidixic acid. The 57 resistant strains were studied to determine whether the resistance was transferable. Forty-three of the 57 resistant strains could transfer part or all of their resistance pattern to a drug-sensitive recipient. The 43 R(+) strains were obtained from 17 of the 23 herds studied. Considerable variation was observed between different R(+) strains in the frequency of transfer of resistance to a particular drug. In addition, variation in the frequency of transfer of different resistance determinants in individual R(+) strains was noted.

Animals↗
PubMed1970

Rapid detection of sublethally impaired cells of Enterobacteriaceae in dried foods.

Samples of dried foods, feeds, and drugs were examined for Enterobacteriaceae by using buffered glucose-Brilliant Green-bile broth as the final enrichment medium and deep tubes of violet-red-bile-glucose-agar for confirmation. The pre-enrichment treatments used for the resuscitation of sublethally impaired cells were overnight incubation in lactose broth versus incubation for 1 to 6 hr at room temperature in shallow layers of tryptone soya peptone broth. The latter restoration treatment appeared to be significantly more productive.

Animal Feed↗
PubMed1970

Identification of Enterobacteriaceae in the clinical microbiology laboratory.

A total of 5,137 enterobacterial clinical isolates were examined with three series of biochemical tests. The data were analyzed with respect to the use of economical and practical procedures for the accurate identification of lactose-fermenting and -nonfermenting Enterobacteriaceae within 24 hr after isolation.

Bacteriological Techniques↗
PubMed1971

R-B enteric differential system for identification of Enterobacteriaceae.

The R/B Enteric Differential System for identifying enteric bacteria has been evaluated with 451 "unknown" cultures from the stock culture collection of the Center for Disease Control. An average of 89.6% of these cultures were correctly identified by the R/B system, when used as recommended by the manufacturer but without the assistance of serology. This percentage ranged, however, from 47% for Klebsiella to 100% for Serratia and Providencia. Of 11 groups or genera of Enterobacteriaceae tested, only three (Enterobacter, Serratia, and Providencia) were identified with 95% or better accuracy. Four groups (Arizona, Citrobacter, Escherichia, and Salmonella) attained 90 to 95% accuracy of identification, and three groups (Edwardsiella, Proteus, and Shigella) scored between 85 and 90% accuracy. We recommend the R/B system as a screening device which is reasonably successful in grouping bacteria but not as a substitute for more exacting conventional procedures.

Bacteriological Techniques↗
PubMed1972

Evaluation of the Auxotab Enteric 1 System for identification of Enterobacteriaceae.

An evaluation of the accuracy and convenience of the Auxotab Enteric 1 System for identification of Enterobacteriaceae was performed with 160 bacteria. Identification at the species level was correct in 134 (83.8%) instances and at the generic level in 144 (90%) instances. Sixty strains failed to achieve the minimal concentration of organisms required to complete the identification process within 7 hr. The system was judged to be laborious and to present a potential hazard to those working with it.

Bacteriological Techniques↗
PubMed1972

Microfermentation series for identification of single colonies of Enterobacteriaceae.

Microfermentation tests for members of the family Enterobacteriaceae were devised by using agar solutions in disposable, multi-welled, plastic trays. The tests could be made directly from isolated colonies picked from agar plates and represented a considerable saving in time, labor, and materials over the conventional methods. Tests were formulated for determining carbohydrate fermentations, citrate utilization, motility, amino acid decarboxylation, and production of H(2)S, indole, urease, and acetyl-methyl-carbinol.

Agar↗
PubMed1973

Evaluation of the redesigned enterotube--a system for the identification of Enterobacteriaceae.

The redesigned Enterotube has been evaluated with 414 unknown Enterobacteriaceae cultures from the stock culture collection of the Center for Disease Control. When the Enterotube was used as recommended by the manufacturer, an average of 96.4% of these cultures were correctly identified. Only two groups (Salmonella and Edwardsiella) were identified with less than 90% accuracy (89.2 and 87.5%, respectively). The Enterotube now provides a convenient, rapid, and accurate test system for the identification of typically reacting enteric bacteria.

Bacteriological Techniques↗
PubMed1973

Urease activity of enterobacteriaceae: which medium to choose.

Detection and intensity of urease activity in enterobacteriaceae greatly varies as a function of the media or techniques used, or both. A comparative investigation on several solid and liquid media led us to the following conclusions. (i) Detection of Proteus spp. can be adequately performed with the highly selective solid medium described by Cook (1948), as well as with the different liquid media described (Stuart standard and rapid media; Elek medium). (ii) Detection of Klebsiella should be based upon urease production on solid media with low buffer capacity (Christensen, 1946). (iii) For the identification of Yersinia, either the solid Christensen urea agar or the rapid Elek technique give optimal results.

Bacteriological Techniques↗
PubMed1976

Formation of crystalline deposits by several genera of the family Enterobacteriaceae.

Several species of bacteria from the family Enterobacteriaceae formed crystalline materials containing calcium when grown in a defined culture medium. Enterobacter aerogenes, Proteus vulgaris, Citrobacter freundii, and C. intermedius produced calcium pyrophosphate crystals. Edwardsiella tarda and Escherichia coli formed calcite III crystals, whereas Proteus mirabilis, Klebsiella pneumoniae, Providencia stuartii, and Serratia marcescens produced hydroxyapatite crystals. Several of these bacteria have been isolated from the kidneys of patients with kidney stones, indicating that microorganisms may be involved in the enucleation process of kidney stone formation.

Calcium Carbonate↗
PubMed1984

Frequency of gene sequences necessary for pyelonephritis-associated pili expression among isolates of Enterobacteriaceae from human extraintestinal infections.

Bacteria representing eight genera of the Enterobacteriaceae were collected from human extraintestinal infections and examined to determine whether they contained gene sequences necessary for expression of a pili type often associated with bacteria causing human pyelonephritis. Escherichia coli isolated from most of the extraintestinal sites were frequently found to possess pap-related DNA sequences. Isolates which possessed these sequences were often found to exhibit D-mannose-resistant hemagglutination of human erythrocytes and to have surface antigens related to P pili.

Animals↗
PubMed1998

alpha-GlcNAc-1-->2-alpha-glc, the Salmonella homologue of a conserved lipopolysaccharide motif in the Enterobacteriaceae, elicits broadly cross-reactive antibodies.

To define cross-reactive epitopes in Salmonella lipopolysaccharide (LPS), antisera designated anti-S, anti-Ra, and anti-Re were generated against smooth (S), complete-core (Ra), and deep-core mutant (Re) strains, respectively, and characterized immunochemically. The reactivities of anti-Ra and anti-S with rough LPS (rLPS) chemotypes in enzyme-linked immunosorbent assays (ELISA) decreased progressively with increasing truncation of the complete-core oligosaccharide (e.g., Ra > Rb1 >.Re), while that of anti-Re increased (Ra < Rb1 <.Re). Anti-Ra was relatively more reactive with nonhomologous smooth LPS (sLPS) than anti-S, which in turn was more reactive than anti-Re. This order reflected the relative reactivities of these sera with outer-core rLPS but not those with inner-core rLPS, which suggests that the cross-reactivities of all three sera with sLPS were mediated by antibodies which bind outer-core determinants. Anti-Ra, but not anti-S or anti-Re, reacted with molecules substituted by O chains in immunoblots and revealed ladder-like patterns in sLPSs of various serospecificities. Anti-Ra, however, did not react with O-antigen-specific neoglycoconjugates in ELISA, thus demonstrating specificity for core epitopes. Ra and Rb1 but not other Salmonella core chemotypes inhibited the reactivity of anti-Ra with sLPS in ELISA, which showed that the terminal outer-core disaccharide, alpha-GlcNAc-1-->2-alpha-Glc (GlcNAc-->Glc), was the major epitope of cross-reactive antibodies in the serum. GlcNAc-->Glc represents the conserved motif alpha-hexose-1-->2-alpha-hexose in cores of the Enterobacteriaceae, other homologues of which should likewise be cross-reactive. These results demonstrate that S or Re strains do not elicit cross-reactive antibodies and indicate that immunization with Ra strains may represent a general strategy for eliciting cross-reactive antibodies against LPSs from enteric bacteria.

Animals↗
PubMed2002

Functional comparison of serine protease autotransporters of enterobacteriaceae.

The plasmid-encoded toxin (Pet) of enteroaggregative Escherichia coli (EAEC) belongs to a family of high-molecular-weight serine protease autotransporters of Enterobacteriaceae (SPATEs) which also includes Pic from EAEC and Shigella flexneri, EspC from enteropathogenic E. coli, EspP from enterohemorrhagic E. coli, Sat from uropathogenic E. coli, Tsh from avian pathogenic E. coli, and SepA from S. flexneri. Phylogenetic analysis shows the SPATE proteins to represent a distinct subfamily of autotransporters with amino acid identities ranging from 35 to 55%, providing a powerful resource to direct structure-function studies. In this study, we show that these related proteins are proteases with divergent substrate specificities, suggesting different functions. The cleavage profile of oligopeptides was found to be unique for each SPATE protein. The SPATEs showed proteolytic activity for several substrates, namely mucin, pepsin, human coagulation factor V, and erythroid spectrin. The cleavage of spectrin has been hypothesized as the mechanism through which Pet induces cytopathic effects. However, whereas Pet, Sat, and EspC cleaved spectrin, only Pet and Sat elicited cytopathic effects; the remaining SPATEs did not cause any morphological changes to HEp-2 cell monolayers. EspC and Pet exhibited acid-dissociable binding to HEp-2 cells. However, Pet was more efficient at entering HEp-2 cells, suggesting a basis for the different abilities of these two proteases to damage cells. Our data suggest that, despite the homologies observed among these proteins, the SPATEs have different pathogenetic functions only partly dependent on their substrate specificities.

Bacterial Proteins↗
PubMed1973

Effect of colon flora and short-chain fatty acids on growth in vitro of Pseudomonas aeruginsoa and Enterobacteriaceae.

Heat-stable antibacterial activity in the following suspensions was demonstrated against Pseudomonas aeruginosa at pH 6.5, 6.0, and 5.5: (i) pooled colon contents of normal mice; (ii) an anaerobic, 48-h culture of normal mouse feces; and (iii) anaerobic, 48-h cultures of different bacteria from human colon flora (Escherichia coli, Bacteroides fragilis, Klebsiella pneumoniae, and Proteus mirabilis). The lower the pH of the medium, the greater was the antibacterial activity of these suspensions. The antibacterial activity of five fatty acids (propionic, butyric, isobutyric, acetic, and formic acids) was greater against P. aeruginosa than against three Enterobacteriaceae (E. coli, K. pneumoniae, and P. mirabilis) at all fatty acid concentrations (0.16 M to 0.005 M) and at the 3 pH values studied (5.5, 6.0, and 6.5). As the pH value increased, the antibacterial activity decreased. Antibacterial activity was greater at higher fatty acid concentrations, and at each pH value it was greatest for the fatty acids having high pK(a) values. Lactic acid, with the lowest pK(a), exhibited little or no antibacterial activity. Acetic and butyric acids, two of the three predominant volatile fatty acids determined by gas chromatography in the mouse colon contents and in the anaerobic culture of mouse feces, occurred in vivo in concentrations which inhibited growth of P. aeruginosa in vitro at the pH of the mouse cecum. These results suggest that undissociated short-chain fatty acids produced by the colon flora may be a mechanism of intestinal resistance to colonization by P. aeruginosa.

Acetates↗
PubMed1972

Enzyme evolution in the Enterobacteriaceae.

An immunological approach has been used for the study of alkaline phosphatase evolution in bacteria of the family Enterobacteriaceae. Antisera were prepared against alkaline phosphatase from Escherichia coli and Klebsiella aerogenes and tested against the unpurified alkaline phosphatases of 32 strains of enterobacteria by double diffusion and quantitative micro-complement fixation. The immunological relationships detected among the alkaline phosphatases of enterobacteria agree approximately with those reported for five other enzymes, as well as with the tryptic peptide pattern similarities found for two other enzymes, and with the relationships detected by interspecific deoxyribonucleic acid hybridization tests.

Alkaline Phosphatase↗