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M H Nicolas-Chanoine

Publications and source records attributed to M H Nicolas-Chanoine.

17 recordsLinked to original sources
PubMed2006

Pasteurella multocida infection of a total knee arthroplasty after a "dog lick".

The patient we report here underwent a total knee arthroplasty (TKA) which got infected with P. multocida after her dog had licked a small wound at the third toe of the same foot. Despite a correct treatment comprising synovectomy and cleansing, and an active antibiotic treatment for 3 months, the patient was readmitted for persistent infection of the same knee 2 weeks after the end of the antibiotic treatment. Sampling during surgery allowed for the growth of a P. multocida isolate proven by a molecular method to be identical to the previously isolated strain. This recurrent P. multocida infection was treated by a two-step change of the TKA comprising a 2-month period of antibiotic treatment between the two surgical interventions.

Aged↗
PubMed2003

Clinical significance of tolerant strains of streptococci in adults with infective endocarditis.

OBJECTIVES: To compare the characteristics of patients with endocarditis due to tolerant and non-tolerant Streptococcus strains. PATIENTS AND METHODS: A retrospective nine-year study was conducted in a single tertiary-care hospital. The study included 24 cases of streptococcal endocarditis with known beta-lactam minimal inhibitory and bactericidal concentrations. RESULTS: Ten of the 24 patients concerned were infected with tolerant streptococcal strains, and 14 with non-tolerant strains. Bacterial tolerance was not associated with higher mortality or increased frequency of surgery. Fewer patients infected with tolerant than non-tolerant strains had serum bactericidal titers reaching success-predictive levels, and more of these experienced failure of initial antibiotic treatment and needed longer treatment. CONCLUSIONS: The results of this study strongly suggest that penicillin tolerance of the streptococci responsible for endocarditis has a clinical impact. Consequently, pending a larger prospective study addressing the problem of tolerance, it is clinically relevant to determine the minimal inhibitory and bactericidal penicillin concentrations for all streptococcal isolates causing endocarditis.

Adult↗
PubMed2002

Susceptibility of Enterobacteriaceae to beta-lactam agents and fluoroquinolones: a 3-year survey in France.

OBJECTIVE: To assess trends in the susceptibility to beta-lactam agents and to fluoroquinolones of clinically relevant Enterobacteriaceae isolated over a 3-year period in 14 French hospital laboratories. METHODS: During the second quarter of 1996, 1997 and 1998, 180 consecutive non-duplicate isolates of Enterobacteriaceae were collected in each center. Sixteen beta-lactams and four quinolones were tested by the disk diffusion method. In addition, the double-disk synergy test was used to screen for the production of extended-spectrum beta-lactamase (ESBL). RESULTS: Totals of 2507, 2312 and 2506 clinical isolates were obtained in each period, respectively. The distribution of Enterobacteriaceae species according to clinical specimens and wards was similar in each study period. No significant variation in the susceptibility rates to beta-lactams and fluoroquinolones was observed, except in Klebsiella pneumoniae and Enterobacter aerogenes. The prevalence of ESBL-producing isolates decreased from 18% to 9% in the former, while it increased from 32% to 54% in the latter. At the same time, the susceptibility to ofloxacin and pefloxacin increased for K. pneumoniae (P < 0.003) and cephalosporinase-producing species (P < 0.05), except Enterobacter spp. CONCLUSION: Over the 3-year study period beta-lactams and fluoroquinolones remained highly active against Enterobacteriaceae clinical isolates, with the exception of E. aerogenes, probably as a result of the dissemination of multiresistant clones in French hospitals.

Anti-Bacterial Agents↗
PubMed2001

Multicenter evaluation of an automated system using selected bacteria that harbor challenging and clinically relevant mechanisms of resistance to antibiotics.

A multicenter study was carried out to evaluate the performance of a new commercial automated system in comparison with that of the reference agar dilution method. Ten clinical microbiology laboratories tested a collection of 61 strains of gram-negative bacilli (49 Enterobacteriaceae and 12 Pseudomonas aeruginosa), and 6 other laboratories tested a collection of 55 strains of gram-positive cocci (10 enterococci and 45 staphylococci) against 10-20 antimicrobial agents. The strains were selected on the basis that they harbored challenging and characterized mechanisms of resistance. In comparison with the agar reference method, the automated system gave an overall essential agreement (+/-1 dilution) of 94.5%, 93.5%, and 97% for the gram-negative bacilli, enterococci, and staphylococci, respectively. According to the interpretive standards of the National Committee for Clinical Laboratory Standards, the category agreement ranged from 96 to 96.4% for the three sets of organisms. The accuracy of the automated system, as determined by the kappa test, ranged from 0.80 to 0.88, reflecting an almost perfect agreement with the reference technique. Very major, major, and minor errors obtained with the automated system were 0.3%, 2.9%, and 6.6% for gram-negative bacilli, 3.4%, 0%, and 5% for enterococci, and 1%, 1.6%, and 2.7% for staphylococci, respectively. The high rate of very major errors in enterococci was mostly due to a single strain of multidrug-resistant Enterococcus faecium, which was found susceptible to several antibiotics in a majority of participant laboratories. The use of a heavy inoculum and of a broth test medium by the automated system might account for a better expression of certain resistance mechanisms, including beta-lactamases, as compared to the agar dilution reference method. The interlaboratory reproducibility was acceptable, as shown by the narrow dispersion of MICs and by the results of quality control.

Anti-Bacterial Agents↗
PubMed2000

Antibiotic susceptibility and mechanisms of beta-lactam resistance in 1310 strains of pseudomonas aeruginosa: a French multicentre study (1996).

A total of 1310 consecutive strains of Pseudomonas aeruginosa were collected in 11 French hospitals in 1996. The percentages of susceptible isolates measured by the agar dilution method were: ticarcillin (53%), piperacillin (69%) (MIC 16 mg/L), ceftazidime (77%), cefepime (55%), cefpirome (40%), aztreonam (57.5%), imipenem (81.5%) (MIC 4 mg/L), amikacin (64.5%) (MIC 8 mg/L) and ciprofloxacin (58%) (MIC 1 mg/L). Resistance to beta-lactams was linked to the production of transferable beta-lactamases (30%), overproduction of cephalosporinase (29%) and to non-enzymic mechanisms (38%).

Anti-Bacterial Agents↗
PubMed1999

Emergence and spread in French hospitals of methicillin-resistant Staphylococcus aureus with increasing susceptibility to gentamicin and other antibiotics.

Oxacillin (methicillin) resistance in methicillin-resistant Staphylococcus aureus (MRSA) is associated with an increased incidence of resistance to other antibiotics, which has increased since it was first reported in 1969. In 1992 a new phenotype of MRSA arose in France; this was characterized by a heterogeneous expression of resistance to oxacillin and susceptibility to various antibiotics, including gentamicin but also tetracycline, minocycline, lincomycin, pristinamycin, co-trimoxazole, rifampin, and fusidic acid. In French hospitals a longitudinal nationwide surveillance of antibiotic resistance in S. aureus has allowed for the detection of changes in antibiotic susceptibility profiles. Seven French clinical laboratories (six from the mainland and one from the West Indies) reported the results of susceptibility testing of 57,347 S. aureus strains isolated in their institutes between 1992 and 1998. Over a 7-year period the incidence of isolation of gentamicin-susceptible MRSA (GS-MRSA) strains has steadily increased to represent, in 1998, 46.8 to 94.4% of the MRSA strains, irrespective of the overall incidence of MRSA. Two predominant types recognized by pulsed-field gel electrophoresis (PFGE) accounted for the majority of the GS-MRSA in different mainland hospitals, both differing from the predominant type observed in the French West Indies. Some GS-MRSA and gentamicin-resistant MRSA (GR-MRSA) strains had closely related PFGE profiles, and hybridization studies confirmed the lack in GS-MRSA of the aac6'-aph2" gene, which confers resistance to all aminoglycosides, with conservation of the ant4' gene, which confers resistance to kanamycin, tobramycin, and amikacin. Thus, it is likely that certain GS-MRSA strains could have emerged from GR-MRSA strains by excision or deletion of the aac6'-aph2" gene.

Cross Infection↗
PubMed1998

X-ray analysis of the NMC-A beta-lactamase at 1.64-A resolution, a class A carbapenemase with broad substrate specificity.

The treatment of infectious diseases by penicillin and cephalosporin antibiotics is continuously challenged by the emergence and the dissemination of the numerous TEM and SHV mutant beta-lactamases with extended substrate profiles. These class A beta-lactamases nevertheless remain inefficient against carbapenems, the most effective antibiotics against clinically relevant pathogens. A new member of this enzyme class, NMC-A, was recently reported to hydrolyze at high rates, and hence destroy, all known beta-lactam antibiotics, including carbapenems and cephamycins. The crystal structure of NMC-A was solved to 1.64-A resolution, and reveals modifications in the topology of the substrate-binding site. While preserving the geometry of the essential catalytic residues, the active site of the enzyme presents a disulfide bridge between residues 69 and 238, and certain other structural differences compared with the other beta-lactamases. These unusual features in class A beta-lactamases involve amino acids that participate in enzyme-substrate interactions, which suggested that these structural factors should be related to the very broad substrate specificity of this enzyme. The comparison of the NMC-A structure with those of other class A enzymes and enzyme-ligand complexes, indicated that the position of Asn-132 in NMC-A provides critical additional space in the region of the protein where the poorer substrates for class A beta-lactamases, such as cephamycins and carbapenems, need to be accommodated.

Amino Acid Sequence↗
PubMed1998

Discriminatory detection of inhibitor-resistant beta-lactamases in Escherichia coli by single-strand conformation polymorphism-PCR.

Plasmid-mediated mechanisms, comprising TEM hyperproduction, TEM derivative production, and OXA production, lead to amoxicillin-clavulanic acid resistance in enterobacteria. The ability of the single-strand conformation polymorphism (SSCP)-PCR method to differentiate the genes encoding inhibitor-resistant beta-lactamases was evaluated with three bla(TEM) primer pairs. The bla(TEM) genes, which were known to be different on the basis of their nucleotide sequences (bla[TEM-1A], bla[TEM-1B], bla[TEM-2], bla[TEM-30], bla[TEM-32], and bla[TEM-35]), were identified as different by their electrophoretic mobilities. The bla(TEM-33), bla(TEM-34), bla(TEM-36), bla(TEM-37), bla(TEM-38), and bla(TEM-39) genes, whose sequence differences have been established by oligotyping, displayed different SSCP profiles for different fragments, suggesting genetic differences in addition to those defined by oligotyping. Confirmed by sequencing, these additional genetic events concerned silent mutations at certain positions and, notably, a G-->T transversion at position 1 of the -10 consensus sequence in bla(TEM-34), bla(TEM-36), bla(TEM-37), and bla(TEM-39). Applied to eight clinical isolates of Escherichia coli resistant to amoxicillin-clavulanic acid, the SSCP method detected TEM-1 in three strains and TEM-30, TEM-32, and TEM-35 in three other strains, respectively. A novel TEM derivative (TEM-58) was detected in another strain, and the deduced amino acid sequence showed two substitutions: Arg244Ser, which is known to confer amoxicillin-clavulanic acid resistance in TEM-30, and Val261Ile, which has not been described previously. The eighth strain produced an OXA beta-lactamase. Given the discriminatory power and the applicability of SSCP-PCR, this method can be proposed as a means of following the evolution of the frequencies of the different inhibitor-resistant beta-lactamases.

Amoxicillin-Potassium Clavulanate Combination↗
PubMed1997

Typing of Clostridium perfringens strains by use of Random Amplified Polymorphic DNA (RAPD) system in comparison with zymotyping.

The definition of strain clonality postulates that strains showed identical phenotypic and genetic traits are likely to descend from a common ancestor even if they were isolated from different sources and locations. Regarding this definition, non-epidemiologically linked strains might be clonal strains. To overcome this ambiguity, the discriminatory capability of RAPD typing was assessed firstly on eight Clostridium perfringens strains proven to be chromosomally different with one being the mutant of another one. Thirteen primers were tested but only two were able to differentiate seven of the eight strains. With none of the used primers it was possible to differentiate the parental strain and its mutant harboring an insertion of 180 kb. The four most discriminant primers were retained to determine the RAPD fingerprints of a further 20 previously zymotyped strains from which seventeen were unrelated. To compare the two typing systems, the zymotype of the eight chromosomally different strains was determined. Thus, the discriminatory index was calculated on the basis of 25 unrelated C. perfringens strains. This was 0.97 with RAPD typing and 0.99 with zymotyping. From these results we conclude that the RAPD typing which is less fastidious than zymotyping can be used as an epidemiological marker for C. perfringens.

Journal Article↗
PubMed1997

Mixed Candida glabrata and Candida albicans disseminated candidiasis in a heroin addict.

The case of a white-heroin addict who developed disseminated candidiasis following coinfection by Candida glabrata and Candida albicans is reported. Genomic random amplified polymorphic DNA typing suggested that the Candida glabrata blood isolates originated in the oral cavity of the patient. This case strengthens the evidence that Candida species other than Candida albicans can be involved in the pathogenesis of disseminated candidiasis in heroin addicts.

AIDS-Related Opportunistic Infections↗
PubMed1997

Reduced susceptibility to co-amoxiclav in Escherichia coli, Salmonella typhimurium and Klebsiella pneumoniae isolated in Romania between 1985 and 1993.

By determining the beta-lactam susceptibility of Enterobacteriaceae isolated in Eastern Romania from 1985 to 1993, three Escherichia coli, three Salmonella typhimurium and one Klebsiella pneumoniae isolates with reduced susceptibility to co-amoxiclav were found. The antibiotic susceptibility of the isolates and their E. coli derivatives, and kinetic values suggested the following resistance mechanisms: hyperproduction of TEM in S. typhimurium, limited antibiotic uptake in K. pneumoniae and OXA production in one strain of E. coli. Despite a normal beta-lactamase activity, the two remaining E. coli strains and their derivatives were less susceptible to co-amoxiclav.

Amoxicillin↗
PubMed1996

A kinetic study of NMC-A beta-lactamase, an Ambler class A carbapenemase also hydrolyzing cephamycins.

In order to analyze its kinetic parameters, an Ambler class A carbapenemase NMC-A was purified. NMC-A demonstrated unusually strong hydrolytic activity towards imipenem and meropenem. Moreover, it hydrolyzed cephamycins with kcat values uncommonly high for this class of beta-lactamases. Clavulanic acid and tazobactam had comparable inhibitory activity against NMC-A, whereas sulbactam was the least active inhibitor. Noticeably, NMC-A was more readily inhibited by brobactam. All these catalytic properties suggest that NMC-A possesses an original structure of its active site allowing hydrolysis of beta-lactams usually stable to the hydrolytic activity of class A beta-lactamases.

Bacterial Proteins↗