Biomedical subjects

Antoine Andremont

Publications and source records attributed to Antoine Andremont.

25 records · Page 2Linked to original sources

PubMed2003

Emergence of resistance in normal human aerobic commensal flora during telithromycin and amoxicillin-clavulanic acid treatments.

Mean fecal global yeast counts increased similarly during 7 days of treatment with telithromycin (800 mg once daily) or amoxicillin-clavulanic acid (amoxiclav) (1 g of amoxicillin and 125 mg of clavulanic acid 3 times daily) in human volunteers and decreased slowly thereafter. On skin, coagulase-negative staphylococci of decreased susceptibility (DS) to telithromycin increased in the telithromycin group, whereas those with DS to methicillin increased in the amoxiclav group. A similar antibiotic-related shift towards homologous DS was observed for oral nongroupable streptococci (NGS), but in addition, the prevalence of NGS resistant to both classes of antibiotics was significantly greater in the amoxiclav group at days 8 (P < 0.01) and 45 (P < 0.015).

Adult↗

PubMed2003

Transcription of quorum-sensing system genes in clinical and environmental isolates of Pseudomonas aeruginosa.

Quorum sensing (QS)-based transcriptional responses in Pseudomonas aeruginosa have been defined on the basis of increases in transcript levels of QS-controlled genes such as lasB and aprA following the hierarchical transcriptional increases of central controllers such as the lasR gene. These increases occur at high bacterial concentrations such as early-stationary-phase growth in vitro. However, the extent to which the increases occur in a variety of clinical and environmental isolates has not been determined nor is there extensive information on allelic variation in lasR genes. An analysis of the sequences of the lasR gene among 66 clinical and environmental isolates showed that 81% have a sequence either identical to that of strain PAO1 or with a silent mutation, 15% have nucleotide changes resulting in amino acid changes, and 5% have an insertion sequence in the lasR gene. Using real-time PCR to quantify transcript levels of lasR, lasB, and aprA in the early log and early stationary phases among 35 isolates from bacteremia and pneumonia cases and the environment, we found most (33 of 35) strains had increases in lasR transcripts in early stationary phase but with a very wide range of final transcript levels per cell. There was a strong correlation (r(2) = 0.84) between early-log- and early-stationary-phase transcript levels in all strains, but this finding remained true only for the 50% of strains above the median level of lasR found in early log phase. There were significant (P < 0.05) but weak-to-modest correlations of lasR transcript levels with aprA (r(2) = 0.2) and lasB (r(2) = 0.5) transcript levels, but again this correlation occurred only in the 50% of P. aeruginosa strains with the highest levels of lasR transcripts in early stationary phase. There were no differences in distribution of lasR alleles among the bacteremia, pneumonia, or environmental isolates. Overall, only about 50% of P. aeruginosa strains from clinical and environmental sources show a lasR-dependent increase in the transcription of aprA and lasB genes, indicating that for about 50% of clinical isolates this regulatory system may not play a significant role in pathogenesis.

Bacterial Proteins↗

PubMed2002

Biodegradable microparticles for the mucosal delivery of antibacterial and dietary antigens.

Mucosal administration of antigen is known to be appropriate for vaccine purposes as well as tolerance induction. Biodegradable poly(DL-lactide-co-glycolide) (PLGA) microparticles were used to deliver both antibacterial phosphorylcholine (PC) and dietary antigen beta lactoglobulin (BLG) by mucosal route. In a first study, the protective immunity elicited by intragastric vaccination with PC encapsulated in microparticles was evaluated in a mouse model against intestinal infection by Salmonella typhimurium and pulmonary infection by Streptococcus pneumoniae. A significant rise in anti-PC immunoglobulin A (IgA) titers, as measured by an enzyme-linked immunosorbent assay, was observed in the intestinal secretions after oral immunization with PC-loaded microparticles compared with the titers of mice immunized with free PC-thyr or blank microparticles. This antibody response correlated with a highly significant resistance to oral challenge by S. typhimurium. IgA in pulmonary secretion were not able to protect against S. pneumoniae infection. BALB/c mice were, therefore, immunized intranasally (i.n.). Immunization was followed by a rise in anti-PC IgA and IgG titers in serum and in pulmonary secretions by both free and encapsulated PC-Thyr. The survival rates were 91 and 76% in the two groups of mice, respectively. In a second study and in order to prevent allergy against milk by inducing oral tolerance, one of the major allergenic milk protein, BLG was entrapped into microparticles. Oral administration of microparticles containing BLG reduced significantly (by 10000) the amount of protein necessary to decrease both specific anti BLG IgE and DTH response. These studies demonstrate the ability of microparticles to induce both mucosal immunity and oral tolerance.

Administration, Intranasal↗

PubMed2002

High frequency of mutator strains among human uropathogenic Escherichia coli isolates.

By using a panel of 603 commensal and pathogenic Escherichia coli and Shigella isolates, we showed that mutation rates of strains vary considerably among different ecotypes. Uropathogenic strains had the highest frequency of mutators, while strains from patients with bacteremia had the lowest mutation rates. No correlation between the mutation rates and antibiotic resistance was observed among the studied strains.

Anti-Bacterial Agents↗

PubMed1998

Use of molecular typing to investigate bacterial translocation from the intestinal tract in malnourished children with Gram-negative bacteremia.

OBJECTIVE: To investigate whether translocation of intestinal Enterobacteriaceae was a likely source of bacteremia in children of 2 years or less hospitalized for fever and moderate malnutrition. METHODS: Blood and fecal cultures were obtained from 198 such children admitted in the Princess Basma Hospital (Irbid, Jordan). Enterobacteriaceae isolated from blood cultures were compared with those present in fecal cultures by genomic typing using pulsed-field gel electrophoresis. The characteristics of children whose blood and fecal strain typing patterns were not distinguishable, i.e. with documented translocation, were compared to those of children without documented translocation. RESULTS: Bacterial translocation was documented in 12 of 19 children (63%) with Enterobacteriaceae bacteremia for whom paired blood and fecal strains were available for genomic typing, and was thus the major source of these bacteremias. The clinical or biological signs of malnutrition were not significantly more pronounced in the bacteremic children with documented translocation than in those without. CONCLUSIONS: We demonstrated that bacterial translocation from the intestinal tract was the most common source of Gram-negative bacteremia in the population studied.

Journal Article↗

PubMed1996

Surveillance of intestinal colonization and of infection by vancomycin-resistant enterococci in hospitalized cancer patients.

OBJECTIVE: To study epidemiologic features of and risk factors for intestinal colonization and infection by vancomycin-resistant enterococci (VRE) in cancer patients. METHODS: During a 41-month period, over 7600 fecal samples and all samples from sterile sites from hospitalized cancer patients were screened for VRE. Species were identified and isolates analyzed by pulsed-field gel electrophoresis (PFGE) of SmaI DNA restriction fragments. Antibiotic resistance was characterized by MIC determinations, and polymerase chain reaction for vanA, vanB, and vanC1 genes. Plasmid contents were analyzed before and after PstI and HindIII restriction, and by Southern hybridization with a vanA probe. Two case-control studies were performed to identify risk factors for colonization or infection by VRE, respectively. RESULTS: Eighty-two isolates were recovered from 81 patients. Most (72%) isolates were Enterococcus faecium VanA/vanA, with 37 different PFGE types, each of which was found in only one to four patients, except for type P1, which was found in 20 patients hospitalized over a 3-month period in the pediatric wards. Plasmid analysis suggested that only two types of plasmid were carrying gene vanA, as part of a transposon related to transposon Tn 1546 from reference strain E. faecium BM4147. Seventy-seven patients were colonized during the study period. Six of them became infected. Four patients were infected but not colonized. Only one patient died during the course of infection, but intestinal colonization persisted for months in the survivors. Case-control analysis revealed that cephalosporin treatment was a significant risk factor for colonization. No significant risk factor for infection was found in colonized patients. CONCLUSION: Colonization by VRE was mostly endemic and the colonized patients were not often infected. However, when clustered cases of colonization occurred, they were then associated with an increased rate of infection.

Journal Article↗

PubMed1996

Secular trends in mortality associated with bloodstream infections in 4268 patients hospitalized in a cancer referral center between 1975 and 1989.

OBJECTIVE: To study the trends in mortality over 15 years in hospitalized cancer patients with bloodstream infection. METHODS: The yearly incidence rates and risk of death, by type of microorganism, were calculated for 4268 cancer patients hospitalized between 1975 and 1989 in a French cancer referral center. The relative risk of death (RR) associated with each type of microorganism was estimated using the proportional hazards model, taking into account age, hospital ward, underlying disease, geographical origin and year of the first positive blood culture. RESULTS: The incidence of these infections was five-fold higher in 1989 than in 1975. The largest increases were for coagulase-negative staphylococci (CNS), yeasts and Staphylococcus aureus. For the 3756 patients who had a single-microorganism bloodstream infection, the risk of death compared with that of patients with CNS infection was significantly increased in those with Pseudomonadaceae (RR=5.0), yeasts (RR=3.4), Enterobacteriaceae (RR=3.2), S. aureus (RR=2.8) and streptococci (RR=2.1). The risk of death was not significantly different between patients with a single or several positive blood cultures nor between those with nosocomial or non-nosocomial infections. When the study period was divided in two time periods (1975 to 1982 vs 1983 to 1989), a significant variation (p=0.001) in risk of death associated with the different microorganisms was observed. Most risks were lower from 1983 to 1986 than before 1982. This decrease reached 60% for both S. aureus and Pseudomonadaceae. CONCLUSIONS: These data support of continuing use of aggressive empirical antimicrobial therapy for cancer patients with fever.

Journal Article↗