Biomedical subjects

B Picard

Publications and source records attributed to B Picard.

At least 19 recordsLinked to original sources

PubMed1992

Esterase electrophoresis compared with biotyping for epidemiological typing of Acinetobacter baumannii strains.

Forty-nine Acinetobacter baumannii strains belonging to three biotypes and isolated from four hospitals were differentiated by electrophoretic typing of their esterases. Six main kinds of esterases were distinguished by their spectra of hydrolytic activity toward seven synthetic substrates. The electrophoretic variations of these enzymes were used to define ten zymotypes among the three biotypes. Esterase electrophoresis appeared to be more sensitive than biotyping, and could represent an additional marker for epidemiological analysis.

Acinetobacter↗

PubMed1992

Two variants of transferrable extended-spectrum TEM-beta-lactamase successively isolated from a clinical Escherichia coli isolate.

In a leukaemic patient presenting a septicaemia treated with ceftazidime and amikacin, two clinical Escherichia coli isolates distinguished by their level of resistance to oxyimino-beta-lactams were isolated at an interval of 24 h. The isolates were identified by biotyping and esterase electrophoretic typing and the two host strains were shown to be identical. However, each of these strains exhibited a different transferrable extended-spectrum beta-lactamase. These enzymes had different pI values (5.25 and 5.58), but were both blaTEM-1 mutants. The enzyme with pI 5.25 was identical to TEM-101 (TEM-12) (serine 162 substitution). The enzyme with pI 5.58 showed an additional amino acid substitution (lysine residue instead of an arginine at position 237) and was denominated TEM-23. These data indicate that point-mutations can be successively cumulated in vivo by blaTEM mutants, leading to expression of beta-lactamases with increased hydrolysis rates.

Bacterial Typing Techniques↗

PubMed1992

Molecular epidemiological analysis of Pseudomonas aeruginosa strains causing failure of antibiotic therapy in cystic fibrosis patients.

A combination of esterase electrophoretic typing and analysis of the restriction fragment length polymorphism of ribosomal DNA regions (ribotyping) was used to compare 27 Pseudomonas aeruginosa strains isolated before and after two-week courses of anti-pseudomonal treatment in seven cystic fibrosis patients. A total of 12 courses of therapy were studied in which ciprofloxacin, ceftazidime, azlocillin or imipenem were used alone or in combination with tobramycin. Isolates at a count of greater than or equal to 10(6) cfu/ml of sputum were collected when there was evidence of therapeutic failure on the basis of persistence of isolates whether or not they were resistant to the antibiotic used for therapy. Emergence of resistance was observed in ten cases and failure to eradicate sensitive strains in five cases. Among the 27 isolates, eight zymotypes and five ribotypes were identified. With this typing approach, resistant post-therapy isolates were found to be identical to pre-therapy isolates in all cases but one. However, in one case an additional resistant strain was isolated after therapy besides that initially present. In all five cases in which susceptibility was still observed after treatment, pre-therapy and post-therapy isolates were indistinguishable. Using this molecular typing approach, all the strains were typable. Thus combination of esterase typing and ribotyping should improve the analysis of therapeutic failure in cystic fibrosis patients.

Azlocillin↗

PubMed1992

Enzyme electrophoretic polymorphism differentiates invasive from non-invasive Chlamydia psittaci ruminant isolates.

A group of 24 Chlamydia psittaci strains isolated from ruminants, belonging to serotype 1 and previously classified as invasive in a mouse model of virulence, was compared to a group of 10 non-invasive strains belonging to serotype 2 by using determination of glucose-6-phosphate and L-malate dehydrogenase zymotypes resulting of the infection of cells by these strains. The serotype 1 or invasive isolates represent a homogeneous group by sharing a unique zymotype which was not observed in the non-invasive strains. On the contrary, the serotype 2 or non-invasive isolates constitute a heterogeneous group in generating 2 different zymotypes. Zymotyping clearly distinguishes the ruminant strains from an avian C. psittaci and two C. trachomatis isolates studied for comparison. Our results suggest the usefulness of the studied molecular approach for chlamydiae typing. Furthermore, it can be used as marker of virulence within the C. psittaci strains isolated from ruminants.

Animals↗

PubMed1992

Molecular epidemiology unravels the complexity of neonatal Escherichia coli acquisition in twins.

Combined analysis of restriction fragment length polymorphism of regions of genes coding for rRNA (ribotyping) and esterase electrophoretic typing was used to document neonatal acquisition of Escherichia coli in twins. Our study shows vertical mother-to-infant transmission of one strain of E. coli to one twin and the development of neonatal septicemia with a distinct nonvirulent carboxylesterase type B1 E. coli strain for the other twin.

Adult↗

PubMed1992

[Characterization of Alcaligenes species using analysis of esterase electrophoretic polymorphism and analysis of antibiotic resistance profiles].

The species of an Alcaligenes bacterial strain may be difficult to determine on the basis of conventional phenotype features. Esterase pattern analysis using acrylamide-agar gel electrophoresis and determination of the antimicrobial resistance profile (agar diffusion method) were performed for A. faecalis (34 strains). A. denitrificans subsp xylosoxydans (16 strains) and A. piechaudi (5 strains). The Cistat program (D2 Software) was used for statistical representation of results. The homogeneous, species-specific esterase patterns ensured correct assignment of each strain to one of the three species. Antimicrobial susceptibility was greatest for A. faecalis which was susceptible to both cephalosporins of all generations and aminoglycosides. A. xylosoxydans was the species with the greatest resistance to antimicrobials. A. piechaudii exhibited intermediate susceptibility.

Alcaligenes↗

PubMed1991

Characterization of highly virulent Escherichia coli strains by ribosomal DNA restriction fragment length polymorphism.

Patterns of ribosomal DNA polymorphism were examined to compare carboxylesterase B type B1 strains and B2 strains of Escherichia coli isolated from extra-intestinal infections. DNA from 14 type B2 strains showing the presence of alpha-haemolysin and mannose-resistant haemagglutinin and lethality to mice and 14 type B1 strains lacking these characteristics, was digested with HindIII, EcoRI, BamHI or BglII restriction enzymes and analysed by Southern blotting. The obtained ribotypes clearly differentiated the B2 strains from the B1 strains. These results indicate that genotypes of the highly virulent B2 strains are different from that of the less virulent B1 strains.

Blotting, Southern↗

PubMed1991

Clonal relationships among Escherichia coli serogroup 06 isolates from human and animal infections.

The clonal relationship of thirty E. coli strains of 0 antigen serotype 06 isolated from human, dog, pig or cow infections were investigated. Two main clones with serotypes 06 : H1 or 06 : H31, H- were identified. Isolates from humans, dogs, pigs and cows were found in both clones, indicating that animals are a possible source for human extraintestinal Escherichia coli strains. Two human ETEC (06 : H16) and two pig isolates (06 : H10) were not related to the 06 : H1 or 06 : H31, H- E. coli clones.

Animals↗

PubMed1991

Pseudomonas aeruginosa isolate typing by esterase electrophoresis.

Esterase electrophoretic typing was used to classify clinical isolates of Pseudomonas aeruginosa. One hundred and twenty-seven P. aeruginosa strains belonging to 16 serotypes (including 16 non-typeable strains) and isolated from diverse human infections in three hospitals, and the type strain ATCC 10 145, were tested. Four main kinds of esterase and 4 additional esterases were distinguished by their spectra of hydrolytic activity toward synthetic substrates and by their sensitivity or resistance to di-isopropyl fluorophosphate. The electrophoretic variations of these enzymes were used to define 42 zymotypes. Electrophoretic typing of esterase appeared to be more sensitive than serotyping and the results of the two methods did not correlate. When the two typing methods were used in parallel, 78 different combinations of serotype and zymotype were obtained.

Bacterial Typing Techniques↗

PubMed1991

Computer-assisted statistical analyses of enzyme and ribosomal DNA electrophoretic polymorphism in Yersinia.

The intra- and inter-species differentiation of 90 strains of Yersinia belonging to six species were studied independently by computer-assisted statistical analysis of data from enzyme electrophoretic polymorphism and ribosomal DNA (rDNA) restriction fragment length polymorphism. Two correspondence analyses (CA) demonstrated the concordance between the bacterial classification obtained from enzymatic and genomic data. This concordance was reinforced by an algorithm of the correspondence established between the two dendrograms drawn from previous computations. Comparison of CA with similarity analysis (also called "numerical taxonomy") indicated that the intra- and inter-species differentiation obtained by the two methods are similar. The advantage of CA is that it gives a synthetic geometrical representation of the results (factorial planes), displaying both the main features of the clusters of strains (location and dispersion) and their essential character (i.e.: enzyme electrophoretic variant, rDNA fragment size).

Algorithms↗

PubMed1991

Comparison of molecular epidemiological tools for Branhamella catarrhalis typing.

Twenty-one Branhamella catarrhalis strains selected for their diversity by esterase electrophoretic polymorphism, and belonging to 20 distinct zymotypes, were studied by restriction fragment length polymorphism (RFLP) of total DNA after ethidium bromide staining and of ribosomal DNA regions (ribotyping). The former analysis allowed the distinction of 20 patterns and the latter the delineation of 19 ribotypes. The three methods were correlated and showed a clonal diversity of the species. Esterase electrophoresis and Hinfl RFLP patterns after ethidium bromide staining appeared to be simple tools for use in B. catarrhalis epidemiology.

Bacterial Typing Techniques↗

PubMed1991

Complexity of Pseudomonas aeruginosa infection in cystic fibrosis: combined results from esterase electrophoresis and rDNA restriction fragment length polymorphism analysis.

Esterase electrophoretic typing and restriction fragment length polymorphism of ribosomal DNA regions (ribotyping) were used to differentiate 102 Pseudomonas aeruginosa clinical isolates obtained from chronic lung infection in 23 patients with cystic fibrosis (CF) and two reference strains (including the type strain ATCC 10145). Twenty-five zymotypes were obtained with the former method and 16 ribotypes with the latter. Combination of the two typing systems led to the finding of 30 different types. Our data highlights the physiopathological complexity of P. aeruginosa infection in CF as, in six individual cases, several types were found among isolates from a given patient. On the other hand, two unique types were found in two and three patients respectively, raising the possibility of cross-infections.

Cystic Fibrosis↗

PubMed1991

Association of carboxylesterase B electrophoretic pattern with presence and expression of urovirulence factor determinants and antimicrobial resistance among strains of Escherichia coli that cause urosepsis.

We determined the carboxylesterase B electrophoretic profiles of 74 blood isolates of Escherichia coli from patients with urosepsis. Most strains (64%) exhibited the B2 electrophoretic pattern. P fimbrial and hemolysin genetic determinants were present and expressed significantly more often among strains with the B2 than with the B1 electrophoretic pattern. In contrast, aerobactin determinants were significantly more prevalent and more commonly expressed among the B1 strains; this difference was attributable to the presence of plasmid-encoded aerobactin in one-third of the B1 strains (P = 0.02, B1 versus B2). The prevalence and extent of antimicrobial resistance was significantly greater among the B1 strains, and the B1 electrophoretic pattern was more often found in isolates from patients with urinary tract abnormalities. We conclude that the carboxylesterase B electrophoretic pattern differentiates two groups of E. coli isolates from patients with urosepsis: strains with the B1 electrophoretic pattern are associated with urologically impaired hosts, characteristically lack P fimbrial and hemolysin determinants, and often carry a plasmid-encoded aerobactin system (possibly on multiple antimicrobial resistance plasmids), whereas B2 strains more commonly invade noncompromised hosts, express P fimbriae and hemolysin, carry chromosomal aerobactin determinants, and lack antimicrobial resistance.

Carboxylesterase↗

PubMed1990

Electrophoresis of gliadins in long acrylamide gels: method and nomenclature.

Gliadins, defined as wheat kernel storage proteins soluble in 70% ethanol, possess an electrophoretic diversity permitting us to identify different varieties. Because of genetic proximity, however, it sometimes proves impossible to distinguish between different varieties using standard methods. An electrophoresis method, utilizing a discontinuous buffer system with aluminum lactate and potassium lactate in the gel and sodium lactate in the electrode vessels, is described for two types of gels 18 cm and 32 cm in length. The number of bands is higher than with standard methods, and is significantly increased with long gels, facilitating the distinction between varieties. A nomenclature for the new bands is presented for several widely different cultivars.

Buffers↗

PubMed1990

An analysis of molecular polymorphism of esterase M produced by motile Aeromonas strains.

The high levels of electrophoretic polymorphism of esterase M detected in eight distinct hybridization groups of motile Aeromonas raise questions of genetic homogeneity of the electromorphs. The 40 electromorphs detected fall in four Mr classes--75, 80, 90, and 110 kD--and one typical variant belonging to each of these classes was purified. The four purified esterases exhibited the same resistance to heat, to pH and to diisopropyl fluorophosphate, the same Km values for 1-naphthyl acetate and 1-naphthyl propionate (1 mM), and immunological cross-reactions. Within each class, the electromorphs appeared to be related in term of single amino acid substitutions as estimated from their comparative titration patterns. The titration curves of the four purified esterases were strictly parallel suggesting close structural similarities. Thus, despite considerable variation in their pI, MF, and Mr values, it seems likely that the variants of esterase M are the products of closely related loci originating from a common ancestral gene.

Aeromonas↗

PubMed1990

Nosocomial Serratia marcescens individualized by five typing methods in a regional hospital.

The relationships between 69 isolates obtained from 26 patients who were affected by two Serratia marcescens hospital outbreaks occurring in the urology and postnatal wards, were examined by five typing methods for epidemiological purposes. Serotyping, antibiotic resistance profile and electrophoretic analysis of enzymes identified three groups of isolates, while biotyping and bacteriocin typing identified only two. These surveys allowed us to demonstrate the existence of independent episodes of cross-infection among patients of each ward.

Bacterial Typing Techniques↗

PubMed1990

Epidemiological typing of Acinetobacter strains by esterase electrophoresis.

Fifty-three strains of Acinetobacter, belonging to the species A baumannii, A. haemolyticus and A. johnsonii, were differentiated by electrophoretic typing of their esterases, on the basis of both the enzyme specific activity profiles and their electrophoretic mobilities. Each esterase was defined by its spectrum of hydrolytic activity toward five synthetic substrates and its sensitivity to di-isopropyl fluorophosphate. Since each enzyme was not detected in all strains of a given species, several zymotypes could be defined by the patterns of combinations of esterases. Thus, 24 zymotypes were defined in the 32 A. baumannii strains, 4 were defined in the 10 A. haemolyticus strains and 6 were defined in the 11 A. johnsonii strains. When the electrophoretic mobilities of the various esterases were included, each of the 53 strains of Acinetobacter (with the exception of three A. haemolyticus strains) showed a distinct electrotype.

Acinetobacter↗

PubMed1990

Characterization of enterobacteria by esterase specific-activity profiles.

The spectrum of specific activities and the electrophoretic mobilities of esterases produced by 550 strains of Enterobacteriaceae belonging to 36 species and subclassified into six groups (group 1, Escherichia coli, Shigella and Escherichia hermanii; group 2, genus Salmonella and genus Citrobacter; group 3, genus Klebsiella and genus Enterobacter; group 4, genus Serratia and Serratia fonticola; group 5, genus Proteus, genus Providencia and genus Morganella; and group 6, genus Yersinia) were analysed by acrylamide/agarose gel electrophoresis using standardized methods for staining and mobility comparisons. Nineteen types of esterase were defined by their respective esterase specific-activity profile (ESAP). A multiple correspondence analysis (MCA) of the ESAP data enabled 82% of the strains in the 36 species to be correctly classified. In each group, the species were clearly delineated after MCA on both ESAP and electrophoretic mobility data. In addition, the smallest number of characters providing species identification of Yersinia strains by esterase polymorphism was identified by means of a binary segmentation tree technique.

Enterobacteriaceae↗