Ulceraçöes aftosas recorrentes bucais: estudo microbiológico / Recurrent aphthous oral ulcers: a microbiologic study

Realizamos estudo microbiológico, coletando amostras de ulceraçöes aftosas recorrentes (UAR) bucais, em 30 pacientes, 18 mulheres e 12 homens, através de "swabs", buscando verificar a participaçäo de bactérias gram-negativas nessas lesöes. Outros 30 pacientes pareados por idade, sexo e estado de saúde bucal, mas com história negativa de UAR foram utilizados como populaçäo controle. Apenas três pacientes do grupo estudo mostraram culturas positivas para gram-negativos (Klebsiella e Enterobacter), enquanto seis pacientes do grupo controle abrigavam enterobactérias. Todas as amostras, tanto do grupo estudo quanto do controle apresentaram crescimento de estreptococos alfa-hemolíticos. Conclui-se que as bactérias gram-negativas näo desempenham papel relevante na expressäo das UAR, uma vez que näo foi possível estabelecer qualquer relaçäo entre as culturas positivas e as características clínicas dos pacientes ou das lesöes em particular. Os estudos devem se aprofundar quanto aos aspectos de identificaçäo, aderência e virulência dos estreptococos alfa-hemolíticos isolados

Carbapenem resistance in Enterobacter aerogenes is due to lipopolysaccharide alterations.

The extensive characterization of 2 clinical Enterobacter aerogenes isolates resistant to all beta-lactam antibiotics including imipenem revealed that imipenem resistance could not be attributed to overproduction of the chromosomal beta-lactamase; moreover, it was lost after subcultivation and can be thus considered as unstable. The comparison of sensitive and resistant clones revealed that the beta-lactamase in the resistant clones was less inducible in the resistant clones and moreover, there was an altered 2-keto-3-deoxyoctonate/carbohydrate ratio in the resistant clones as compared to the imipenem-sensitive clones, thus suggesting alterations in the lipopolysaccharide (LPS). Neither enzymatic degradation of both imipenem and meropenem nor alterations of the outer membrane proteins could be observed. These findings make it apparent that this type of resistance is likely due to an impaired uptake of the agents due to LPS alterations.

Immunochemical studies on levans from several strains of Actinomyces viscosus.

High molecular-weight levans elaborated by 8 separate strains of Actinomyces viscosus were purified: the inteactions of these levans with concanavalin A and anti-fructan myeloma immunoglobulins UPC-10 and J606 were examined by the quantitative precipitin method. Oligosaccharides released from the levans by partial acid hydrolysis were separated by partition chromatography on paper and characterized in situ by selective spray reagents. The liberated oligomers were compared with oligomers of known structure released from levans of Aerobacter levanicum and Leuconostoc mesenteriodes B512 as well as with plant inulin. The fragmentation analysis indicated a structure for Actinomyces levans comprising chains of beta (2----6)-linked fructofuranosyl units joined through multiple (1,2,6)-linked fructosyl branch units.

Isolation and characterization of agglomerins A, B, C and D.

New antibiotics, agglomerins A, B, C and D, were isolated from the culture broth of a bacterial strain identified as Enterobacter agglomerans. These antibiotics are acidic in nature and their sodium salts are obtained as colorless crystalline powders, soluble in lower alcohols. All the antibiotics shows characteristic UV maxima at 248 and 298 nm. Molecular formulas: A, C15H21O4Na; B, C17H23O4Na; C, C17H25O4Na and D, C19H27O4Na; were indicated by elemental analysis and MS. These antibiotics are active against a wide variety of anaerobic bacteria and weakly against aerobic Gram-positive bacteria in vitro.

Evaluation of numerical analysis of SDS-PAGE of protein patterns for typing Enterobacter cloacae.

Twenty cultures comprising 13 clinical isolates of Enterobacter cloacae from two hospitals, the type and another reference stain of E. cloacae and the type strains of four other Enterobacter sp. and of Escherichia coli, were characterized by one-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of whole-cell proteins. The protein patterns were highly reproducible and were used as the basis of a numerical analysis which divided the clinical isolates into nine clearly defined protein types. Comparison with established typing methods indicated that the discrimination of SDS-PAGE was similar to that achieved with conventional typing methods and all strain groups recognized by combined sero/phage typing were also found by SDS-PAGE. In addition, protein typing sub-divided a group of four serotype O3 isolates that were difficult to distinguish by phage typing. We conclude that high-resolution SDS-PAGE of proteins provides an effective method of typing isolates of E. cloacae.

[Bacterial and parasitological surveillance of untreated and treated sewage in the city of Tunis]. / Surveillance bactériologique et parasitologique des eaux usées brutes et traitées de la ville de Tunis.

The concentration of faecal contamination test-germs in wastewater has been determined at the entrance and the exit of three purification plants. Investigation for salmonella in the affluents and effluents of the three treatment plants proved that the systems of purification do not permit complete elimination of pathogenic bacteria from wastewaters. Helmith eggs has been observed in raw and treated wastewaters. Compared to the biological intensive systems, the lagoon treatment is susceptible to produce effluent with the best bacteriological and parasitical quality.

Structure of the O-specific polysaccharide from Enterobacter cloacae strain N.C.T.C. 11579 (serogroup O10).

The O-specific polysaccharide from the reference strain (N.C.T.C. 11579) for Enterobacter cloacae serogroup O10 has been isolated and characterised. By means of n.m.r. spectroscopy and methylation analysis, and by studies of the products obtained by Smith degradation or by N-deacetylation-deamination, the repeating unit of the polysaccharide could be allocated the structure shown. The polysaccharides from two cross-reacting serogroups (O9 and O11) have the same monosaccharide composition. (Formula: see text)

Comparison of multidimensional scaling and principal component analysis of interspecific variation in bacteria.

Multidimensional scaling (MDS) and principal component analysis (PCA) were applied to bacterial taxonomy. The biochemical profiles of 42 isolates consisting of four species of Enterobacteriaceae were used. Both MDS and PCA use proximity measures such as the correlation coefficient or Euclidean distance to generate a spatial configuration (map) of points in multidimensional space where distances between points reflect the similarity among isolates. Multidimensional scaling and principal component analysis were able to discriminate organisms in two dimensions. The test components of the MDS and PCA factors (derived variables composed of linear combination of biochemical tests) were different for a two-dimensional solution.

[Bacteria reducing chromium in nature and in effluents of industrial plants]. / Bakterii, vosstanavlivaiushchie khrom v prirode i v stokakh proizvodstvennykh predpriiatii.

Bacteria capable of hexavalent chromium (Cr6+) reduction can be found in Cr6+-containing sewage and sediments of purification tanks of industrial plants. They cannot be detected in water and soil samples containing no chromium compounds. Bacteria reducing chromium belong to the genera Aeromonas, Escherichia, Pseudomonas and Enterobacter. Their activity of Cr6+ reduction correlates with the high resistance to the elevated content of this ion in the medium. The fine cell structure of these bacteria is described.

High-performance liquid chromatographic analysis of demethylmenaquinone and menaquinone mixtures from bacteria.

Demethylmenaquinone and menaquinone mixtures from some species of enterobacteria were analysed by reverse-phase partition high-performance liquid chromatography. This method allowed clear separation and quantitative determination of these quinone components.

Emergence of resistance to ceftazidime during therapy for Enterobacter cloacae infections.

The mechanism of resistance to ceftazidime in two clinical isolates of Enterobacter cloacae that emerged during therapy with broad-spectrum beta-lactam antibiotics was studied. Both isolates acquired broad resistance to advanced-spectrum beta-lactam drugs other than imipenem. Biotyping confirmed strain identity in both cases, and no new plasmids were detected in the resistant isolates. Both resistant isolates produced beta-lactamase constitutively. Slow but definite hydrolysis of ceftazidime was demonstrated by using purified beta-lactamase in a spectrophotometric assay. Further evidence that beta-lactamase is responsible for resistance in these organisms was provided by the demonstration that cefoxitin, a potent inducer of beta-lactamase, antagonized the activity of ceftazidime against these isolates. This antagonism could be prevented by inhibition of derepression of beta-lactamase with clindamycin. Clindamycin also prevented regrowth of ceftazidime-treated cells in time-kill studies and markedly reduced production of beta-lactamase in induced cultures at concentrations as low as 2 micrograms/ml.

Interspecific reconstitution of maltose transport and chemotaxis in Escherichia coli with maltose-binding protein from various enteric bacteria.

In Escherichia coli, the periplasmic maltose-binding protein (MBP), the product of the malE gene, is the primary recognition component of the transport system for maltose and maltodextrins. It is also the maltose chemoreceptor, in which capacity it interacts with the signal transducer Tar (taxis to aspartate and some repellents). In studies of the maltose system in other members of the family Enterobacteriaceae, we found that MBP is produced by Salmonella typhimurium, Klebsiella pneumoniae, Enterobacter aerogenes, and Serratia marcescens. MBP from all of these species cross-reacted with antibody against the E. coli protein and had a similar molecular weight (about 40,000). The Shigella flexneri and Proteus mirabilis strains we examined did not synthesize MBP. The isoelectric points of MBP from different species varied from the acid extreme of E. coli (4.8) to the basic extreme of E. aerogenes (8.9). All species with MBP transported maltose with high affinity, although the Vmax for K. pneumoniae was severalfold lower than that for the other species. Maltose chemotaxis was observed only in E. coli and E. aerogenes. In S. typhimurium LT2, Tar was completely inactive in maltose taxis, although it signaled normally in response to aspartate. MBP isolated from all five species could be used to reconstitute maltose transport and taxis in a delta malE strain of E. coli after permeabilization of the outer membrane with calcium.

Cross-resistance to nalidixic acid, trimethoprim, and chloramphenicol associated with alterations in outer membrane proteins of Klebsiella, Enterobacter, and Serratia.

We studied in vitro mutants of Klebsiella, Enterobacter, and Serratia cross-resistant to nalidixic acid, trimethoprim, and chloramphenicol that were similar to mutants found in vivo. The sole mechanism for this type of resistance appeared to be a reduction in permeability of the cell envelope. The mutants had significantly lower rates of uptake of glucose and chloramphenicol, but binding of chloramphenicol to ribosomes was normal. In addition, the amounts of dihydrofolate reductase were similar in both wild-type and cross-resistant mutants of Klebsiella. Examination of the bacterial outer membrane revealed that the amount of at least one major protein, with a molecular size of approximately 40 kilodaltons, was decreased in the mutants. Therefore the resistance seemed likely to be due to the reduction in quantity of these outer membrane proteins, possibly porins, in the mutant bacteria.

Composition of O-antigenic lipopolysaccharides from Enterobacter cloacae.

Analyses have been carried out on lipopolysaccharides (LPS) from 14 strains of Enterobacter cloacae representing different O serotypes. All of the products appeared to have a composition and architecture typical of enterobacterial LPS, but points of interest include the absence of phosphate residues from the core oligosaccharide, the presence of both L-glycero-D-mannoheptose and D-glycero-D-mannoheptose (ratio usually about 4:1), and the presence in lipid A of small amounts of fatty acids with odd numbers of carbon atoms (mainly C13) in addition to tetradecanoic acid and 3-hydroxytetradecanoic acid. Monosaccharides identified as components of polymeric fractions from the LPS were glucose, galactose, mannose, rhamnose, glucosamine, galactosamine, fucosamine, and galacturonic acid. Most polymeric fractions also probably contained an O-acetyl substituent. Closely similar chemotypes found for the polymeric fractions from the LPS of cross-reacting serotypes support the view that these fractions contain the O-antigenic determinants and represent the side chains of the LPS.

[Heterogeneity of the fatty acid composition of bacteria in the genera Klebsiella, Enterobacter, Hafnia and Serratia]. / Geterogennost' zhirnokislotnogo sostava bakterii rodov Klebsiella, Enterobacter, Hafnia i Serratia.

The analysis of the chromatograms of methyl esters of fatty acids in bacterial strains of the tribe Klebsielleae showed the heterogeneity of the fatty acid composition of bacteria belonging to the genera Klebsiella, Enterobacter, Hafnia and Serratia. The bacteria of this tribe could be subdivided into 5 provisory groups in accordance with the composition and profile of their fatty acids. Group I comprised K. pneumoniae K1, K. ozaenae and K. rhinoscleromatis strains forming a separate group characterized by the absence of cyclopropane fatty acids; group II comprised K. pneumoniae strains of other capsular serovars (K2, K8, K11, K13, K41, K47), as well as K. aerogenes and K. oxytoca strains. The fatty acid composition of the strains of group III, comprising E. aerogenes and E. cloacae, was similar to that of E. coli O1; only among the fatty acids of these bacteria acid C20:0 could be detected. H. alvei strains were included into group IV; their fatty acid profiles were similar to those of the genus Enterobacter, but had a higher content of acids C15:0 and C18:0. S. marcescens strains were similar to the strains of group II in their fatty acid composition, but considerably differed from the latter by a higher content of hexadecanoate (C16:0) and a lower level of C18:1; for this reason they were regarded as provisory group V.

Bacteriocin typing of clinical isolates of Enterobacter cloacae.

A total of 16 selected bacteriocins of Enterobacter cloacae were characterized presumptively. They proved to be noninfectious, sedimentable (105,000 X g), resistant against chloroform and trypsin, and nonfilterable. The host ranges were essentially species specific. Based on susceptibility to one or more of these 16 bacteriocins, 242 of 308 (78.6%) clinical E. cloacae isolates were typed and assigned to 52 provisional bacteriocin types. Several outbreaks of nosocomial cross-infection were discerned retrospectively. Thus, bacteriocin typing of E. cloacae isolates may prove useful for controlling hospital infection.

Direct comparison of two mechanized systems for identification of gram-negative bacilli. Autobac ID system versus the auto microbic system (with EBC plus).

The Auto Microbic System (AMS) is an almost completely automated system, capable of identifying Enterobacteriaceae after 8 hours, and some glucose nonfermenters after 13 hours of incubation. The Autobac ID system is a mechanized, computer-assisted system capable of identifying Enterobacteriaceae and many nonfermentative gram-negative bacilli within 3-6 hours. The present report combines the results of two independent studies, both of which evaluated the AMS and the Autobac ID system compared with standard reference tests. Among the 1,510 isolates that were tested, both systems reported equivocal identifications (low confidence values) with 5-6% of the strains. AMS produced fewer erroneous identifications (3.8% vs. 4.9%) but more equivocal test results (5.7% vs. 4.9%). Reproducibility of the two systems was compared by triplicate testing of 88 selected strains in both laboratories. AMS was somewhat more reproducible than the Autobac ID system. The AMS was capable of identifying more species with greater accuracy and reproducibility, but the Autobac ID system was more rapid. Both systems demonstrated excellent accuracy and reproducibility and both could be used efficiently in the clinical laboratory.