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E Van Wijngaerden

Publications and source records attributed to E Van Wijngaerden.

At least 19 recordsLinked to original sources
PubMed2006

Simultaneous determination of 8 HIV protease inhibitors in human plasma by isocratic high-performance liquid chromatography with combined use of UV and fluorescence detection: amprenavir, indinavir, atazanavir, ritonavir, lopinavir, saquinavir, nelfinavir and M8-nelfinavir metabolite.

A simple, accurate and fast method was developed for determination of the commonly used HIV protease inhibitors (PIs) amprenavir, indinavir, atazanavir, ritonavir, lopinavir, nelfinavir, M8-nelfinavir metabolite and saquinavir in human plasma. Liquid-liquid extraction was used with hexane/ethylacetate from buffered plasma samples with a borate buffer pH 9.0. Isocratic chromatographic separation of all components was performed on an Allsphere hexyl HPLC column with combined UV and fluorescence detection. Calibration curves were constructed in the range of 0.025-10 mg/l. Accuracy and precision of the standards were all below 15% and the lowest limit of quantitation was 0.025 mg/l. Stability of quality control samples at different temperature conditions was found to be below 20% of nominal values. The advantages of this method are: (1) inclusion and determination of the newly approved atazanavir, (2) simultaneous isocratic HPLC separation of all compounds and (3) increased specificity and sensitivity for amprenavir by using fluorescence detection. This method can be used for therapeutic drug monitoring of all PIs currently commercialised and is now part of current clinical practice.

Atazanavir Sulfate↗
PubMed2005

Three cases of destructive native valve endocarditis caused by Staphylococcus lugdunensis.

Described here are three cases of acute native valve endocarditis due to the coagulase-negative pathogen Staphylococcus lugdunensis with serious complications. Two of the three patients died despite optimal antibiotic therapy and cardiovascular surgery. These cases demonstrate the aggressive nature of S. lugdunensis and emphasize the importance of identifying coagulase-negative staphylococci to the species level and not considering the isolation of S. lugdunensis from normally sterile body fluids as contamination. On the contrary, when this organism is found in patients with endocarditis, early surgery should be considered. The possibility that this organism could be misidentified as S. aureus because of "autocoagulation" and that commercial identification systems may misidentify it as S. haemolyticus, S. hominis or S. warneri should also be remembered.

Adult↗
PubMed2001

Evaluation of two commercial kits for the detection of genotypic drug resistance on a panel of HIV type 1 subtypes A through J.

We compared the two commercially available sequencing kits for HIV-1 drug resistance testing, the ViroSeq Genotyping System (Applied Biosystems, Foster City, CA, U.S.A.) and the TRUGENE HIV-1 Genotyping Kit (Visible Genetics, Inc., Toronto, Ontario, Canada), with our in-house genotyping system. Fifteen viral isolates from African patients (6 treated and 9 untreated) covering a panel of HIV-1 subtypes A through J and 7 plasma samples from Belgian and African patients (2 treated and 5 untreated) were tested. All the samples could be amplified and sequenced by the three systems; however, for all systems, alternative amplification/sequencing primers had to be used for some samples belonging to subtype B as well as to other subtypes. The consensus sequence was partially derived from only one strand for the in-house system and for the ViroSeq Genotyping System. The TRUGENE HIV-1 Genotyping Kit scored the highest number of ambiguities, followed by the ViroSeq Genotyping System and the in-house system. For 11 samples, these differences in reporting mixtures affected 14 resistance-related positions, which altered the interpretation toward protease inhibitors for 2 samples when using version 1.2 RetroGram software (Virology Networks, Utrecht, The Netherlands). All three systems were able to sequence diluted samples with a viral load down to 10 3 or 10 4 RNA copies/ml. Our data therefore suggest that the performance of amplification and sequencing primers must be improved to allow fast and reliable resistance testing for all HIV-1 subtypes.

Drug Industry↗
PubMed2001

Candidal vertebral osteomyelitis: report of 6 patients, and a review.

The incidence of deep-seated candidal infection is increasing, but candidal vertebral osteomyelitis is still rare. We describe 6 patients recently treated in our hospital. Conservative treatment failed in all. We reviewed the literature and identified 59 additional cases of candidal vertebral osteomyelitis. Candidemia was documented in 61.5% of them. The interval between the diagnosis of candidemia and the onset of symptoms of vertebral osteomyelitis varied widely, from days to >1 year. In patients without documented candidemia, there was a similar interval between the occurrence of risk factors for candidemia (present in 72% of the patients) and the onset of symptoms of vertebral osteomyelitis. Clinical, laboratory, and radiological findings are not specific for candidal spondylodiskitis. Final diagnosis is determined by means of culture of a biopsy specimen from the infected vertebra or disk. Treatment consisted of prolonged antifungal treatment, and it often included surgery. On the basis of our experience (for all 6 patients, initial conservative treatment with only antifungals failed), we recommend consideration of early surgical debridement in combination with prolonged antifungal therapy.

Adolescent↗
PubMed2001

Frequency of transient streptococcal bacteremia following urgent orotracheal intubation in critically ill patients.

OBJECTIVES: To examine whether urgent orotracheal intubation (OI) can induce bacteremia. To find predictive factors for post-intubation bacteremia. DESIGN: Prospective observational study. SETTING: Seventeen-bed medical intensive care unit in a university hospital. PATIENTS: Sixty-eight adult intensive care patients undergoing urgent OI. MEASUREMENTS AND RESULTS: Patients in need of OI could be included if no cardiopulmonary resuscitation was performed. A blood culture was taken immediately before, as soon as possible after, and 60 min after intubation. The indication for intubation, ease of intubation, and the antibiotics used before intubation were registered. Six patients (6/68 or 9%) had streptococcal bacteremia immediately (mean 10.8 min) after intubation. No patient (0/62) had streptococcal bacteremia 60 min after intubation (P = 0.01). Four of the six patients showing streptococcal bacteremia after intubation were intubated by a second doctor because of difficulties during intubation, whereas this was the case in only 9/62 in those without streptococcal bacteremia (P = 0.01). Four of the 13 patients (31%) who needed to be intubated by a second doctor showed transient streptococcal bacteremia. Of the 20 patients not receiving antibiotics at the time of intubation, four (20%) had streptococcal bacteremia compared with 2/47 (4.2%) patients receiving antibiotics (P = 0.06). CONCLUSIONS: Urgent intubation can cause transient bacteremia with streptococci in a significant proportion of intensive care patients. The observed frequency of bacteremia is higher than previously reported after elective intubation. The difficulty of intubation is probably a predisposing factor.

Bacteremia↗
PubMed2001

Polyclonal Staphylococcus epidermidis intravascular catheter-related infections.

During a 4-month period we prospectively investigated the frequency of polyclonal catheter infections with Staphylococcus epidermidis. Of each catheter with pure growth of S. epidermidis, six colonies were genotypically analyzed with pulsed-field gel electrophoresis. Two out of 12 patients with catheter infection had a polyclonal infection. Both clones of each catheter had a clearly different antibiotic susceptibility. This study shows that polyclonal catheter infections are not exceptional. Further studies are needed to define the clinical consequences of polyclonal catheter infection.

Adult↗
PubMed2001

Difference in time to positivity of hub-blood versus nonhub-blood cultures is not useful for the diagnosis of catheter-related bloodstream infection in critically ill patients.

OBJECTIVE: The differential time to positivity (DTTP), defined as the difference in time necessary for the blood cultures taken by a peripheral puncture and through the catheter to become positive has been suggested to be useful in differentiating between catheter-related bloodstream infection (CR-BSI) and other sources of bacteremia. A DTTP of >120 mins was found predominantly in CR-BSI. The objective of our study was to investigate whether DTTP is useful for the diagnosis of CR-BSI in a medical-surgical intensive care unit. DESIGN: Prospective clinical study. SETTING: A 60-bed medical-surgical intensive care unit of a university hospital. PATIENTS: One hundred consecutive adult patients from whom catheter(s) were to be removed for suspected CR-BSI were studied. INTERVENTION: A blood culture (using aerobic and anaerobic culture bottles) was first taken from a new puncture site. Next, a blood culture was taken through every intravascular catheter in place. MEASUREMENTS AND RESULTS: DTTP was calculated using the automated BacT/Alert blood culture system. Three patients had CR-BSI and nine patients had noncatheter-related bacteremia. Five patients had catheter-related sepsis without proven bacteremia. There was no significant difference in median DTTP between patients with CR-BSI and noncatheter-related bacteremia (2.1 hrs and 3.3 hrs, respectively; p =.6). Moreover, catheter-related sepsis in patients without bacteremia could not be detected using DTTP. CONCLUSION: DTTP seems not to be useful for the diagnosis of CR-BSI in a medical-surgical intensive care unit.

Adult↗
PubMed2000

Presence of 2',5'-Bis-O-(tert-butyldimethylsilyl)-3'-spiro-5"-(4"-amino-1",2"-oxath iole-2",2"-dioxide) (TSAO)-resistant virus strains in TSAO-inexperienced HIV patients.

HIV-1 samples from six patients undergoing diverse anti-HIV therapies possessed the E138A mutation in their reverse transcriptase (RT) genome. Patients were receiving the following therapies: TIBO monotherapy (one patient); zidovudine plus didanosine combination therapy (one); zidovudine monotherapy (one); sequential therapy with zidovudine, then stavudine and finally zalcitabine plus didanosine (one); and two were drug naive. E138K, not E138A, is a known TSAO-specific resistance mutation, emerging under selective pressure in vitro. Our phenotypic data on the patient isolates, confirmed by data on an E138A mutant acquired through in vitro mutagenesis, indicated that an alanine substitution for glutamate at codon 138 of the HIV-1 RT renders the virus TSAO resistant, confirming the importance of this amino acid residue in the activity of TSAO derivatives. In addition, we have demonstrated through phenotypic analysis of the E138A and A98S mutants (after in vitro mutagenesis) that the mutation A98S, found in one of these patients, could be partially responsible for the phenotypic reversal of TSAO resistance. This reversal could be explained by the restoration of a hydrogen bond between 98S and the main-chain residue L349, which compensates for the loss of the E138-G99 main-chain hydrogen bond. As TSAO derivatives have not been used in the clinical setting, the presence of the E138A mutation at a frequency of 6.7% in our study of 90 TSAO-inexperienced HIV-seropositive individuals implies that 138A of the RT must be a natural variant and that the mutant virus is replication competent. Our observations suggest that the E138A mutation may likely arise in patients under the selective pressure of TSAO or related compounds that show a decreased antiviral potency toward the E138A variant.

Anti-HIV Agents↗
PubMed2000

Baseline HIV type 1 genotypic resistance to a newly added nucleoside analog is predictive of virologic failure of the new therapy.

We evaluated the predictive value of baseline HIV-1 genotypic resistance mutations for failure of a nucleoside reverse transcriptase inhibitor (NRTI) containing therapy. The change in therapy of 88 HIV-1-infected patients was analyzed retrospectively, relating the genotypic resistance profile at baseline to the evolution of viral load and CD4+ T cell counts. Genotypic resistance at baseline and at 6 months was evaluated with the LiPA HIV-1 RT, which detects mutations at codons 41, 69, 70, 74, 184, and 215. At 1 to 3 months after change in therapy, patients without preexisting resistance mutations to the new drug (group S) had a significantly better evolution in viral load (reduction of 0.37 log(10)) compared with patients with known preexisting resistance mutation(s) (group R) (increase of 0.08 log(10)). This difference was particularly striking for patients with the baseline M184V mutation and whose treatment was modified by the addition of lamivudine. After 6 months the median difference in viral load evolution between the two groups increased to 0.61 log(10): the viral load of patients of group S was still 0.18 log(10) below baseline while patients of group R had an increase of 0.43 log(10) in viral load above baseline. Changes in CD4+ T cell counts were not significantly different. The evolution in viral load in HIV-1-infected patients with and without baseline resistance mutation(s) toward a newly added NRTI is significantly different at 1-3 months and at 6 months after changing or adding one NRTI.

CD4 Lymphocyte Count↗
PubMed2000

Prevalence and characteristics of multinucleoside-resistant human immunodeficiency virus type 1 among European patients receiving combinations of nucleoside analogues.

The prevalence and the genotypic and phenotypic characteristics of multinucleoside-resistant (MNR) human immunodeficiency virus type 1 (HIV-1) variants in Europe were investigated in a multicenter study that involved centers in nine European countries. Study samples (n = 363) collected between 1991 and 1997 from patients exposed to two or more nucleoside analogue reverse transcriptase inhibitors (NRTIs) and 274 control samples from patients exposed to no or one NRTI were screened for two marker mutations of multinucleoside resistance (the Q151M mutation and a mutation with a 2-amino-acid insertion at codon 69, T69S-XX). Q151M was identified in six of the study samples (1. 6%), and T69S-XX was identified in two of the study samples (0.5%; both of them T69S-SS), but both patterns were absent among control samples. Non-NRTI (NNRTI)-related changes were observed in viral strains from two patients, which displayed the Q151M resistance pattern, although the patients were NNRTI naive. The patients whose isolates displayed multinucleoside resistance had received treatment with zidovudine and either didanosine, zalcitabine, or stavudine. Both resistance patterns conferred broad cross-resistance to NRTIs in vitro and a poor response to treatment in vivo. MNR HIV-1 is found only among multinucleoside-experienced patients. Its prevalence is low in Europe, but it should be closely monitored since it seriously limits treatment options.

Amino Acid Substitution↗
PubMed1999

Phenotypic assays and sequencing are less sensitive than point mutation assays for detection of resistance in mixed HIV-1 genotypic populations.

The sensitivity and discriminatory power of the 151 and 215 amplification refractory mutation system (ARMS) were evaluated, and their performance for the detection of drug resistance in mixed genotypic populations of the reverse transcription (RT) gene of HIV-1 were compared with T7 sequencing, cycle sequencing, the line probe assay (LiPA) HIV-1 RT test, and the recombinant virus assay (RVA). ARMS and the LiPA HIV-1 RT test were shown to be able to detect minor variants that in particular cases comprised only 1%. T7 sequencing on an ALF semiautomated sequencer could correctly score mixtures only when variants were present at 50%. Cycle sequencing on an ABI PRISM 310 improved the sensitivity for mixtures to about 25%. Using RVA, it was shown that at least 50% of the virus population needed to carry the resistance mutation at codon 184 to afford phenotypic resistance against lamivudine. The two point mutation assays therefore proved to be more sensitive methods than sequencing and RVA to reliably determine a gradual shift in HIV-1 drug resistance mutations in follow-up of patients infected with HIV-1. In 4 of 5 treated patients who were followed by ARMS, a gradual shift in resistant genotypic populations was observed during a period of 6 to 19 months. For 1 patient, a shift from wild to mutant type at position 151 occurred within 2 months, without mixed genotypic intermediate type's being detected.

DNA Mutational Analysis↗
PubMed1999

Long-term stability of human immunodeficiency virus viral load and infectivity in whole blood.

BACKGROUND: We intended to evaluate the stability of human immunodeficiency virus (HIV) type 1 virions in whole blood and in culture medium. MATERIALS AND METHOD: EDTA whole-blood samples taken from 12 patients were left at room temperature for up to 7 days, and aliquots of a laboratory virus stock spiked in EDTA, in heparinized or in citrated whole blood, with or without the addition of Triton X-100, or spiked in culture medium were left at room temperature for up to 120 days before plasma was separated and frozen at -80 degrees C. Viral load was measured for all frozen plasma samples using different viral load assays. p24 antigen and infectivity were also measured in the spiked samples. RESULTS: The patient whole-blood samples did not show any decrease in viral load during this 7-day period. The spiked samples decayed by not more than 1 log after 120 days (about 4 months), with the fastest decay in medium. Virus infectivity decayed very slowly from 20,000 units mL-1 to undetectable amounts after 56 days. CONCLUSIONS: These results indicate that HIV-1 virions in whole blood possess a long-term stability in terms of viral load, p24 antigen level and infectivity, which is not sufficiently recognized by laboratory and health care workers.

Freezing↗