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Biomedical subjects

V Jarlier

Publications and source records attributed to V Jarlier.

At least 37 records · Page 2Linked to original sources
PubMed2004

Outbreak of Burkholderia cepacia bacteremia in a pediatric hospital due to contamination of lipid emulsion stoppers.

We describe a 7-month outbreak of nosocomial Burkholderia cepacia bacteremia involving eight children in a pediatric hospital and the results of epidemiological investigations. A B. cepacia strain genotypically identical to the blood isolates was recovered from the upper surface of capped rubber stoppers of bottles of a commercial lipid emulsion used for parenteral nutrition.

Bacteremia↗
PubMed2003

Growth on blood agar discriminates Mycobacterium avium and Mycobacterium intracellulare.

Mycobacterium intracellulare and Mycobacterium avium (MAC) require specialized culture and identification procedures. To simplify the diagnosis, we inoculated reference strains, and 85 M. avium and 12 M. intracellulare clinical isolates, on egg-based and sheep blood agar. After 5 days of culture, there were significantly more colonies on sheep blood than on egg-based agar for M. avium (ratio: 250.5 +/- 209) but not for M. intracellulare (ratio: 0.44 +/-0.11). Using a ratio > or = 20, the sensitivity of the identification of an MAC isolate as M. avium was 97.65%, the specificity was 100%, and the positive predictive value was 100%. Differential growth on egg-based and blood agar is an aid to the identification of MAC isolates.

Agar↗
PubMed2003

Multidrug-resistant tuberculosis: eight years of surveillance in France.

The aim of this study was to evaluate the annual prevalence of multidrug-resistant tuberculosis (MDRTB) and to describe the characteristics of the patients with MDRTB in France. Annual questionnaire surveys from 1992-1999 were mailed to all French microbiological laboratories performing mycobacterial cultures. A total of 264 distinct patients were reported to the National Reference Centre for Resistance of Mycobacteria to Antituberculosis Drugs during the 8-yr surveillance period resulting in a mean annual prevalence of MDRTB of 0.6%. A mean of 16% of the MDRTB patients were reported over several subsequent years. The majority of patients were male (69.7%), foreign-born (55.7%), with a previous history of treatment (65.9%), and pulmonary involvement (92.8%) with smear-positive results (59.1%). Human immunodeficiency virus (HIV) coinfection was present in 20.8% of the patients. Strains were resistant only to isoniazid and rifampin in 37.9% of the cases, and additional resistance to both streptomycin and ethambutol was present in 25.8%. HIV coinfection and female status were statistically associated with primary resistance, whereas smear-positive results were associated with secondary resistance. Foreign-birth and smear-positive results were associated with a chronic status. The prevalence of multidrug-resistant tuberculosis is low in France (<1%). However, a substantial proportion of patients remain positive for several years, suggesting nonoptimal management. Therefore, as recommended by the World Health Organization, a few reference teams, working in collaboration with national associations of physicians and microbiologists, should be established to improve the outcome of multidrug-resistant tuberculosis.

Adolescent↗
PubMed2002

[Evolution of susceptibility of aerobic gram-negative aerobic bacilli to quinolones and fluoroquinolones in a university hospital (1992-2000)].

Susceptibility to quinolones of aerobic gram-negative bacilli was assessed in a 2000-bed university hospital from 1992 to 2000. There was a significant downward trend in the rate of susceptibility to nalidixic acid (Nal) for Enterobacteriaceae as a whole from 1992 to 2000 (86% vs 82%), and E. coli (92% vs 84%), and an upward trend for K. pneumoniae (74% vs 82%), the latter being related to the control of the spread of epidemic ESBL producing strains. The overall susceptibility of Enterobacteriaceae to ciprofloxacin (Cip) paralleled the susceptibility to Nal: decreased susceptibility for Enterobacteriaceae as a whole (96% vs 89%) and E. coli (99% vs 91%). A clear decrease in the level of susceptibility to Cip occurred during the study period among the Nal-resistant strains as demonstrated by the decrease in the median zone diameter (D) observed among the Nal-resistant strains of E. coli (26 mm in 1992 vs 19 mm in 1998-2000). The zone diameter distribution pattern changed from an unimodal distribution in 1992 to a trimodal distribution in 2000 secondary to the occurrence of a population of resistant strains (D = 13 mm) and of a highly resistant population (D = 6 mm). Finally, the susceptibility to Cip of P. aeruginosa strains remained stable around 62% throughout the study period.

4-Quinolones↗
PubMed2001

Crystal structures of the class D beta-lactamase OXA-13 in the native form and in complex with meropenem.

The therapeutic problems posed by class D beta-lactamases, a family of serine enzymes that hydrolyse beta-lactam antibiotics following an acylation-deacylation mechanism, are increased by the very low level of sensitivity of these enzymes to beta-lactamase inhibitors. To gain structural and mechanistic insights to aid the design of new inhibitors, we have determined the crystal structure of OXA-13 from Pseudomonas aeruginosa in the apo form and in complex with the carbapenem meropenem. The native form consisted of a dimer displaying an overall organisation similar to that found in the closely related enzyme OXA-10. In the acyl-enzyme complex, the positioning of the antibiotic appeared to be ensured mainly by (i) the covalent acyl bond and (ii) a strong salt-bridge involving the carboxylate moiety of the drug. Comparison of the structures of OXA-13 in the apo form and in complex with meropenem revealed an unsuspected flexibility in the region of the essential serine 115 residue, with possible consequences for the catalytic properties of the enzyme. In the apo form, the Ser115 side-chain is oriented outside the active site, whereas the general base Lys70 adopts a conformation that seems to be incompatible with the activation of the catalytic water molecule required for the deacylation step. In the OXA-13:meropenem complex, a 3.5 A movement of the backbone of the 114-116 loop towards the side-chain of Lys70 was observed, which seems to be driven by a displacement of the neighbouring 91-104 loop and which results in the repositioning of the side-chain hydroxyl group of Ser115 toward the catalytic centre. Concomitantly, the side-chain of Lys70 is forced to curve in the direction of the deacylating water molecule, which is then strongly bound and activated by this residue. However, a distance of ca 5 A separates the catalytic water molecule from the acyl carbonyl group of meropenem, a structural feature that accounts for the inhibition of OXA-13 by this drug. Finally, the low level of penicillinase activity revealed by the kinetic analysis of OXA-13 could be related to the specific presence in position 73 of a serine residue located close to the general base Lys70, which results in a decrease of the number of hydrogen-bonding interactions stabilising the catalytic water molecule.

Amino Acid Sequence↗
PubMed2001

Study of the structure-activity relationships for the pyrazinamidase (PncA) from Mycobacterium tuberculosis.

In an attempt to investigate the molecular basis of pyrazinamide hydrolysis by the PncA protein from Mycobacterium tuberculosis, we determined the pyrazinamidase activity of nine PncA mutants bearing a single amino acid substitution. Among them, three mutants (D8G, K96T and S104R) had virtually no activity (< or =0.004 unit/mg), five (F13S, T61P, P69L, Y103S and A146V) retained a low level of activity (0.06-0.25 unit/mg) and one (T167L) exhibited a wild-type activity (1.51 units/mg). The possible structural effects of these substitutions were assessed by analysing a three-dimensional model of the PncA protein constructed on the basis of the crystal structure of the N-carbamoylsarcosine amidohydrolase (CSHase) from Arthrobacter sp., an amidohydrolase which was found by hydrophobic cluster analysis to be closely related to PncA. In the PncA model, five of the mutated residues, Asp-8, Phe-13, Lys-96, Tyr-103 and Ser-104, were located within a 6 A sphere around the cysteine residue Cys-138, which could be the counterpart of the active cysteine residue Cys-177 found in the CSHase. Among the remaining mutated residues, Thr-61, Pro-69 and Ala-146 were found to be more distant from Cys-138 but were associated with structural elements contributing to the catalytic centre, whereas Thr-167 was situated in an alpha-helix located far from the putative active site. These data suggest that the decrease in pyrazinamidase activity observed in the PncA mutant proteins is well correlated with the structural modifications the mutations can cause in the environment of the putative active cysteine Cys-138.

Amidohydrolases↗
PubMed2001

Surveillance of antimicrobial resistance--what, how and whither?

OBJECTIVE: To express the views of a working party held to consider antibiotic resistance surveillance systems, their strengths and weaknesses, and their current and future applications. METHODS: The participants, all of whom were experienced in this field, discussed the development of surveillance systems in relation to the increasing prevalence of resistance to antibacterial agents and the current interest in surveillance systems shown by many official bodies, in both the human and veterinary fields. The problems inherent in surveillance systems were considered together with the applications of different systems. RESULTS: The properties of good antibiotic resistance surveillance systems were defined. Surveillance systems vary widely from those with a narrow base, focusing on few organisms in one disease area, to those covering many diseases, many organisms (including normal flora) and many compounds. Whatever their design, they should be able to detect significant differences and shifts in susceptibility to various antibacterial agents, and the information derived from them should reach as many interested parties as possible in a timely manner. In using this information to decide strategies, criteria for action need to be determined by pragmatic consensus. Funding remains a major problem, with few large studies being supported by official bodies in spite of their professed enthusiasm for surveillance. In consequence, many current systems are funded by the pharmaceutical industry and are of necessity restricted in their focus. CONCLUSIONS: Antibiotic resistance surveillance studies should and can be well planned and well executed. Many current systems suffer from well-recognized but uncorrected biases. Consortium funding will be necessary for large schemes to be successful. There is no "ideal" surveillance system.

Animals↗
PubMed2001

Trends in quinolone susceptibility of Enterobacteriaceae among inpatients of a large university hospital: 1992-98.

OBJECTIVES: To assess trends in quinolone susceptibility of Enterobacteriaceae isolated in a large university hospital. METHODS: Between 1992 and 1998, bacterial isolates were collected each year during a 3-month period to evaluate annual changes in susceptibility. In addition, the activities of fluoroquinolones (pefloxacin, norfloxacin, ofloxacin, ciprofloxacin) against nalidixic acid-resistant strains were determined by disk diffusion and MIC methodologies during the first and last year of the study. RESULTS: The susceptibility of Enterobacteriaceae to nalidixic acid was unchanged between 1992 and 1998 (86% versus 85%). However, at the species level, the susceptibility rates to nalidixic acid decreased for Escherichia coli from 92% to 89%, and for Enterobacter cloacae from 87% to 82%. In contrast, there was a 10% increase in the nalidixic acid susceptibility rates for Klebsiella pneumoniae (74% versus 83%), which was thought to be due to the control of the spread of epidemic extended-spectrum beta-lactamase (ESBL)-producing strains. The overall susceptibility of the Enterobacteriaceae to the fluoroquinolones remained high during the study period, greater than 90% in the case of ciprofloxacin. However, nalidixic acid-resistant Escherichia coli showed decreased susceptibility to ciprofloxacin between 1992 and 1998, as reflected by a decrease in median zone diameter (26 mm to 19 mm), an increase in MIC(50) (0.25 mg/L to 1 mg/L) and a shift in MIC distribution (unimodal in 1992 to bimodal in 1998). This has resulted in the reduced susceptibility of Escherichia coli to fluoroquinolones between 1992 and 1998 (pefloxacin, 95-90%; ciprofloxacin, 99-95%). CONCLUSIONS: The susceptibility of Escherichia coli to quinolones has decreased, and the level of susceptibility of the resistant strains has increased over the 7-year study period.

Anti-Infective Agents↗
PubMed2001

Activities of new macrolides and fluoroquinolones against Mycobacterium ulcerans infection in mice.

Mice infected in the left hind footpad with 5 log(10) acid-fast bacilli of Mycobacterium ulcerans were divided into an untreated control group and 17 treatment groups that received one of the following regimens for 4 weeks (all doses in milligrams per kilogram): 100 mg of azithromycin (AZM), 100 mg of clarithromycin (CLR), or 50 mg of AZM for a duration of 5 days a week (daily), three times a week, or once weekly. In addition, the following regimens were administered daily: 100 mg of telithromycin (TLM), sparfloxacin (SPX), or moxifloxacin (MOX); 200 mg of levofloxacin (LVX); 100 mg of streptomycin (STR) or amikacin (AMK); 10 mg of rifampin (RIF); and the combination of 10 mg of RIF and 100 mg of AMK (RIF+AMK). After completion of treatment, mice were observed for 30 weeks. The effectiveness of treatment regimens was assessed in terms of the delay in median time to footpad swelling in treated mice compared with that in the untreated controls. Clear-cut bactericidal activity, i.e., an observed delay in footpad swelling that exceeded the period of treatment, was observed in the STR-, AMK-, and RIF+AMK-treated mice. However, all mice treated with either AMK or STR alone had swollen footpads before the end of the 30-week observation period, suggesting regrowth of M. ulcerans. In contrast, 50% of the mice treated with the RIF+AMK combination exhibited no lesion even after 30 weeks, suggesting cure. The remaining regimens could be assigned to one of three groups: (i) no activity (50 mg of AZM, 100 mg of AZM thrice weekly, TLM, and LVX); (ii) bacteriostatic activity, i.e., a delay in footpad swelling shorter than the 4-week treatment duration (100 mg of AZM daily or once weekly, CLR thrice or once weekly, and MOX); or (iii) weak bactericidal activity (CLR daily and SPX). The RIF+AMK combination and possibly RIF+STR warrant further study for the treatment of M. ulcerans infection in humans.

Animals↗
PubMed2001

In vitro activities of ertapenem (MK-0826) against recent clinical bacteria collected in Europe and Australia.

Ertapenem (MK-0826, L-749,345) is a 1-beta-methyl carbapenem with a long serum half-life. Its in vitro activity was determined by broth microdilution against 3,478 bacteria from 12 centers in Europe and Australia, with imipenem, cefepime, ceftriaxone, and piperacillin-tazobactam used as comparators. Ertapenem was the most active agent tested against members of the family Enterobacteriaceae, with MICs at which 90% of isolates are inhibited (MIC(90)s) of < or =1 microg/ml for all species. Ertapenem also was more active than imipenem against fastidious gram-negative bacteria and Moraxella spp.; on the other hand, ertapenem was slightly less active than imipenem against streptococci, methicillin-susceptible staphylococci, and anaerobes, but its MIC(90)s for these groups remained < or =0.5 microg/ml. Acinetobacter spp. and Pseudomonas aeruginosa were also much less susceptible to ertapenem than imipenem, and most Enterococcus faecalis strains were resistant. Ertapenem resistance, based on a provisional NCCLS MIC breakpoint of > or =16 microg/ml, was seen in only 3 of 1,611 strains of the family Enterobacteriaceae tested, all of them Enterobacter aerogenes. Resistance was also seen in 2 of 135 anaerobes, comprising 1 Bacteroides fragilis strain and 1 Clostridium difficile strain. Ertapenem breakpoints for streptococci have not been established, but an unofficial susceptibility breakpoint of < or =2 microg/ml was adopted for clinical trials to generate corresponding clinical response data for isolates for which MICs were as high as 2 microg/ml. Of 234 Streptococcus pneumoniae strains tested, 2 required ertapenem MICs of 2 microg/ml and one required an MIC of 4 microg/ml, among 67 non-Streptococcus pyogenes, non-Streptococcus pneumoniae streptococci, single isolates required ertapenem MICs of 2 and 16 microg/ml. These streptococci also had diminished susceptibilities to other beta-lactams, including imipenem as well as ertapenem. The Etest and disk diffusion gave susceptibility test results in good agreement with those of the broth microdilution method for ertapenem.

Anti-Bacterial Agents↗
PubMed2001

Novel class A beta-lactamase Sed-1 from Citrobacter sedlakii: genetic diversity of beta-lactamases within the Citrobacter genus.

Citrobacter sedlakii 2596, a clinical strain resistant to aminopenicillins, carboxypenicillins, and early cephalosporins such as cephalothin, but remaining susceptible to acylureidopenicillins, carbapenems, and later cephalosporins such as cefotaxime, was isolated from the bile of a patient treated with beta-lactam and quinolone antibiotics. The isolate produced an inducible class A beta-lactamase of pI 8.6, named Sed-1, which was purified. Characterized by a molecular mass of 30 kDa, Sed-1 preferentially hydrolyzed benzylpenicillin, cephalothin, and cloxacillin. The corresponding gene, bla(Sed-1), was cloned and sequenced. Its deduced amino acid sequence shared more than 60% identity with the chromosome-encoded beta-lactamases from Citrobacter koseri (formerly C. diversus) (84%), Klebsiella oxytoca (74%), Serratia fonticola (67%), and Proteus vulgaris (63%) and 71% identity with the plasmid-mediated enzyme MEN-1. A gene coding for a LysR transcriptional regulator was found upstream from bla(Sed-1). This regulator, named SedR, displayed 90% identity with the AmpR sequence of the chromosomal beta-lactamase from C. koseri and 63 and 50% identity with the AmpR sequences of P. vulgaris and Enterobacter cloacae, respectively. By using DNA-DNA hybridization, a bla(Sed-1)-like gene was identified in two reference strains, C. sedlakii (CIP-105037) and Citrobacter rodentium (CIP-104675), but not in the 18 strains of C. koseri studied. Two DNA fragments were amplified and sequenced from the reference strains of C. sedlakii CIP-105037 and C. rodentium CIP-104675 using two primers specific for bla(Sed-1). They shared 98 and 80% identity with bla(Sed-1), respectively, confirming the diversity of the chromosomally encoded class A beta-lactamases found in Citrobacter.

Amino Acid Sequence↗
PubMed2000

Mycobacterial growth indicator tube versus the proportion method on Löwenstein-Jensen medium for antibiotic susceptibility testing of Mycobacterium tuberculosis.

The Mycobacterial Growth Indicator Tube, a reliable system for detection of mycobacterial growth, was compared with the reference proportion method on Löwenstein-Jensen medium for antibiotic susceptibility testing of Mycobacterium tuberculosis. A total of 62 clinical strains and four reference strains of Mycobacterium tuberculosis were tested for susceptibility to streptomycin, isoniazid, rifampicin and ethambutol. Of these, 36 were susceptible to all four antibiotics and 30 were resistant to at least one of them. Tests were repeated in cases of discrepant results. When each drug/strain combination was considered separately, the overall agreement between the two methods was 96.5% (98.4% for streptomycin, 95.3% for isoniazid, 96.9% for rifampicin and 95.3% for ethambutol) with regard to the initial testing and 98.8% (100, 98.5, 98.5 and 98.4%, respectively) after repeated testing. When the results were considered strain by strain, the agreement was 86% after the initial testing and 95% after repeated testing. The results were obtained after a mean time of 9.5 days. These results suggest that the Mycobacterial Growth Indicator Tube is a reliable method for testing susceptibility of mycobacterial strains to first-line antituberculous drugs.

Antitubercular Agents↗
PubMed2000

Antibiotic susceptibility pattern of Mycobacterium marinum.

In vitro activities of 17 antibiotics against 53 clinical strains of Mycobacterium marinum, an atypical mycobacterium responsible for cutaneous infections, were determined using the reference agar dilution method. Rifampin and rifabutin were the most active drugs (MICs at which 90% of the isolates tested were inhibited [MIC(90)s], 0.5 and 0.6 microgram/ml, respectively). MICs of minocycline (MIC(90), 4 microgram/ml), doxycycline (MIC(90), 16 microgram/ml), clarithromycin (MIC(90), 4 microgram/ml), sparfloxacin (MIC(90), 2 microgram/ml), moxifloxacin (MIC(90), 1 microgram/ml), imipenem (MIC(90), 8 microgram/ml), sulfamethoxazole (MIC(90), 8 microgram/ml) and amikacin (MIC(90), 4 microgram/ml) were close to the susceptibility breakpoints. MICs of isoniazid, ethambutol, trimethoprim, azithromycin, ciprofloxacin, ofloxacin, and levofloxacin were above the concentrations usually obtained in vivo. For each drug, the MIC(50), geometric mean MIC, and modal MIC were very close, showing that all the strains had a similar susceptibility pattern. Percent agreement (within +/-1 log(2) dilution) between MICs yielded by the Etest method and by the agar dilution method used as reference were 83, 59, 43, and 24% for minocycline, rifampin, clarithromycin, and sparfloxacin, respectively. Reproducibility with the Etest was low, in contrast to that with the agar dilution method. In conclusion, M. marinum is a naturally multidrug-resistant species for which the agar dilution method is more accurate than the Etest for antibiotic susceptibility testing.

Anti-Bacterial Agents↗
PubMed2000

Activities of several antimicrobials against Mycobacterium ulcerans infection in mice.

Mycobacterium ulcerans inoculated into the footpads of mice at 6 x 10(3) CFU was shown to have a generation time of 6.5 days when estimated from weekly changes in microscopic counts of acid-fast bacilli (AFB) and 7.5 days when calculated from actual CFU enumerated on Lowenstein-Jensen egg medium incubated at 32 degrees C. Footpads became swollen at week 10 (W10) after infection, and all infected control mice were dead at W15 after infection. Daily (5 days/week) treatment with 100 mg of clarithromycin (CLR)/kg of body weight beginning the day after infection prevented swelling of footpads at W10. When initiation of treatment was delayed until obvious footpad swelling was observed, there was a reduction in both the increase in AFB counts and deterioration of swollen footpads and also a prolonged survival of the mice to W18. Mice infected in the hind footpads with 5 x 10(5) CFU of M. ulcerans were divided into an untreated control group and six treatment groups that received one of the following therapies for 8 weeks: 100 mg of CLR/kg, 25 mg of minocycline (MIN)/kg, 50 mg of sparfloxacin (SPX)/kg, 10 mg of rifampin (RIF)/kg, 10 mg of rifabutin (RBT)/kg, or 100 mg of amikacin (AMK)/kg. After completion of therapy, treated animals were observed for an additional 17 weeks. All control mice and mice treated with CLR, MIN, or SPX exhibited swollen footpads during the observation period. In contrast, of those animals treated with RIF, RBT, or AMK, none had footpad swelling and all inoculated cultures done after the W17 observation remained negative. These results suggest that RIF, RBT, and AMK may be effective in the treatment of human infection with M. ulcerans.

Animals↗
PubMed2000

Twenty-five years of tuberculosis in a French university hospital: a laboratory perspective.

OBJECTIVE: To determine the impact of recent changes in the epidemiology of tuberculosis in France and other industrialised countries on the primary trends of tuberculosis case rates in a French university hospital. DESIGN: Descriptive study of all 4549 culture-positive tuberculosis cases hospitalised at Pitié-Salpêtrière Hospital between 1972 and 1996. RESULTS: From 1972, there was a decline of 5% per year in the tuberculosis case rate, which levelled off in 1983. The proportion of tuberculosis patients who were human immunodeficiency virus (HIV) positive increased from 2% in 1983 to 28% in 1990, and thereafter remained stable. The proportion of foreign-born tuberculosis patients also increased, from 40% in 1972 to 55% in 1985. These two changes affected drug resistance patterns. Drug resistance was more common among foreign-born than among French-born patients, whether previously treated or not. Resistance to rifampicin and multidrug resistance among previously untreated patients was highly related to HIV co-infection. Extrapulmonary sites of tuberculosis were more often smear-positive in HIV-positive than in non-HIV-positive patients (22.8% vs 12.6%), and bacteraemia was diagnosed almost exclusively in HIV-positive patients. CONCLUSION: The changes in clinical and bacteriological tuberculosis patterns at the hospital level over the last 25 years have paralleled those observed at national and international level in industrialised countries, including a slowing in the decrease in the case rate, due in part to the HIV epidemic, a higher proportion of foreign-born patients and an increase in drug resistance.

AIDS-Related Opportunistic Infections↗