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R J Courcol

Publications and source records attributed to R J Courcol.

At least 37 records · Page 2Linked to original sources
PubMed1995

Influence of iron depletion on growth kinetics, siderophore production, and protein expression of Staphylococcus aureus.

Growth rates, siderophore secretion, and bacterial proteins of two clinical isolates of Staphylococcus aureus were studied over 72 h of growth in iron-supplemented and iron-restricted chemically defined media. Under iron restriction the growth rates were decreased to different extents depending on the strain. Production of siderophore was detected in the mid-exponential and stationary phases of growth. The expression of iron-regulated proteins of 81, 23, and 17 kDa was time-dependent, associated with the same stage of growth, and might be involved in siderophore efficiency.

Bacterial Outer Membrane Proteins↗
PubMed1995

Bactericidal effect of beta-lactams and amikacin alone or in association against Klebsiella pneumoniae producing extended spectrum beta-lactamase.

Ten extended spectrum beta-lactamases producing strains of Klebsiella pneumoniae characterized by analytical isoelectric focusing and studied for their susceptibility to beta-lactam antibiotics, either alone or in combination with a beta-lactamase inhibitor (clavulanic acid and sulbactam) and in association with amikacin. The extended spectrum beta-lactamases were derived from either TEM (CTX-1 = TEM-3) or SHV (CAZ-4 = SHV-5). Killing curves were studied with antibiotics at clinical by achievable concentrations, at MIC and MIC x 4. At MIC, cefotetan, cefotaxime and ceftazidime lacked bactericidal activity. Imipenem was more rapidly bactericidal than meropenem or co-amoxiclav. At MIC x 4, cefotetan and cefotaxime exhibited bactericidal effect but this was less than for imipenem which gave a reduction of 4 log10 of the inoculum. Cefotaxime plus sulbactam gave no bactericidal effect compared with cefotaxime plus co-amoxiclav. A bactericidal effect with cefotaxime plus sulbactam was seen with the addition of amikacin. At clinical concentrations cefotaxime plus co-amoxiclav +/- amikacin was as efficient as imipenem +/- amikacin with a rapid bactericidal effect (5-6 log10 in 30-60 min). We proposed that cefotaxime+co-amoxiclav might be considered as an alternative to imipenem for the treatment of extended spectrum beta-lactamase associated K. pneumoniae injections.

Amikacin↗
PubMed1993

Bactericidal activity of selected antimicrobial agents against Bilophila wadsworthia and Bacteroides gracilis.

Bactericidal assays of Bacteroides gracilis (six strains) and Bilophila wadsworthia (12 strains) in brucella broth with appropriate supplements were performed by the time-kill kinetic method. Antimicrobial agents tested were ampicillin/sulbactam (final concentrations, 16/8 micrograms/mL), ticarcillin/clavulanate (128/2 micrograms/mL), imipenem (8 micrograms/mL), cefoxitin (32 micrograms/mL), chloramphenicol (16 micrograms/mL), clindamycin (4 micrograms/mL), and metronidazole (16 micrograms/mL). Although all antimicrobial agents tested inhibited growth of all Bilophila strains during the first 24 hours, bactericidal activity was variable; only metronidazole was uniformly bactericidal. Most strains of Bilophila showed 1-2 log increases in growth at 6 hours with clindamycin and chloramphenicol. With chloramphenicol, some Bilophila strains tested showed regrowth starting at 30 hours. B. gracilis strains were generally more susceptible to all agents tested. Metronidazole, ticarcillin/clavulanate, chloramphenicol, and imipenem were most active. Several strains of B. gracilis were not killed by ampicillin/sulbactam, clindamycin, or cefoxitin. Activity was variable among strains and antimicrobial agents.

Anti-Bacterial Agents↗
PubMed1993

Effectiveness of resins in removing antibiotics from blood cultures.

The present study evaluates the effectiveness of BACTEC NR-26A resin-containing medium in removing eight antibiotics from blood cultures. Peak concentrations achievable clinically were chosen. All antibiotics were prepared in fresh human blood samples. Blood samples were obtained prior to and at 15 min and 2, 24, 48, and 72 h after inoculation. Aztreonam, ceftriaxone, imipenem, teicoplanin, and ticarcillin were partially removed from blood cultures.

Anti-Bacterial Agents↗
PubMed1992

BioArgos: a fully automated blood culture system.

BioArgos (Sanofi Diagnostics Pasteur, Marnes-la-Coquette, France) is a fully automated blood culture system that detects carbon dioxide production by infrared spectroscopy through a glass bottle. This hands-off system was compared with the BACTEC NR-660 system (Becton Dickinson Diagnostic Instrument Systems, Towson, Md.). A total of 336 microorganisms belonging to 74 taxa were tested in simulated blood cultures by both systems. Experimental data showed no significant differences between the two systems. The inclusive detection times (+/- the standard deviations) were 33.2 +/- 28.7 and 35.0 +/- 30.6 h with BioArgos and BACTEC, respectively. Anaerobes were detected earlier with BioArgos, whereas detection of some organisms that need oxygen to grow was slightly delayed. In conclusion, BioArgos is as reliable and accurate as BACTEC NR-660 and shows better practicability owing to noninvasive detection, reduction of vial manipulation, and absence of daily maintenance.

Aerobiosis↗
PubMed1991

Effects of iron depletion and sub-inhibitory concentrations of antibodies on siderophore production by Staphylococcus aureus.

The effect of various sub-MICs of oxacillin and amikacin, alone or in combination, on siderophore production by Staphylococcus aureus growing under iron-depleted conditions was evaluated. Siderophore production varied greatly from strain to strain, ranging from 3.0 to 383.4 microM of Desferal equivalents. Siderophore production by some S. aureus strains was reduced significantly (P less than 0.001) under some sets of conditions. However, siderophore excretion in cultures with amikacin was sometimes equal to or greater than control cultures. Thus, at some sub-MICs, the bacteria tested were able to increase siderophore production under metabolic stress. This phenomenon may be a secondary effect of the antibiotics upon intermediary metabolism as a consequence of inhibition of peptidoglycan or protein synthesis. Alternatively the antibiotics may decrease the cellular association of siderophore molecules.

Amikacin↗
PubMed1989

Influence of blood carbon dioxide pressure on growth index values in non-radiometric Bactec vials.

The influence of blood carbon dioxide pressure on growth index values yielded by the Bactec NR 660 system was evaluated. Growth index values of 1,175 Bactec blood culture vials collected from 293 patients were related to blood pCO2 and leukocyte concentrations. Thirty-three blood cultures were considered false-positive. These were significantly more frequently encountered in hypercapnia patients (5.4%) than in hypocapnia patients (1.7%) or normal patients (2.5%). There was no relationship between the growth index values and leukocyte concentrations.

Bacteria↗
PubMed1989

A seven year survey of antibiotic susceptibility and its relationship with usage.

Bacterial susceptibilities to 14 antibiotics of 7385 clinical isolates, belonging to six species of Gram-negative bacilli, were analysed during seven years (1980-86). The recovery of Serratia marcescens, Acinetobacter calcoaceticus and Pseudomonas aeruginosa increased while their sensitivity to antibiotics decreased significantly, especially to aminoglycosides and tetracycline. There were significant correlations between increase in antibiotic use and decrease in susceptibility. There was a striking relationship between third-generation cephalosporin use and increasing number of isolates of the species mentioned above.

Anti-Bacterial Agents↗
PubMed1988

Routine evaluation of BACTEC NR-16A and NR-17A media.

The purpose of this study was to determine whether the BACTEC NR-16A and NR-17A media were more effective than the BACTEC NR-6A and NR-7A media in recovering organisms from the blood of patients undergoing antimicrobial therapy. A total of 986 sets of four blood culture bottles were compared, giving 141, 174, 93, and 104 isolates with BACTEC NR-6A, NR-16A, NR-7A, and NR-17A, respectively. BACTEC NR-6A and NR-7A media recovered 234 isolates, whereas BACTEC NR-16A and NR-17A media recovered 278 isolates. The recovery rate of bacteria when aerobic resin media were used was better than that with conventional aerobic media (P less than 0.001). The mean detection times were 51.5 and 69.7 h with NR-16A and NR-6A, respectively (P less than 0.01), whereas they were 68.2 and 71.3 h with NR-17A and NR-7A, respectively (P greater than 0.05). The small number of anaerobes recovered precluded a statistical comparison of relative recovery for that group of organisms.

Aerobiosis↗
PubMed1987

Computerized colonization-surveillance based on antimicrobial susceptibility patterns.

In order to estimate the occurrence of hospital-acquired colonizations, a specific program based on antimicrobial susceptibility tests was developed for the early recognition of clusters of colonized patients. This program allowed: (a) estimation of the endemic level of nosocomial colonization every three days within an intensive care unit; (b) detection of outbreak of hospital-acquired infections; (c) distinction between primary and secondary infections according to the dates of admission and collection; (d) provision of the latest profiles of susceptibility to antimicrobials for the 5 pathogens studied (Staphylococcus aureus, S. epidermidis, Serratia spp., Pseudomonas spp., Acinetobacter spp.). This study reported the experience of a two-year trial in colonization surveillance.

Bacteriological Techniques↗