Search PubMed⌕ Search

Biomedical subjects

W J van Leeuwen

Publications and source records attributed to W J van Leeuwen.

At least 19 recordsLinked to original sources
PubMed2001

Quantitative tibial ultrasonometry versus radiographic phalangeal absorptiometry in a Caucasian pediatric population.

There is a need for a reliable bone assessment technique in children. In this study, we compare an existing technique used in children, radiographic absorptiometry (RA), with a relatively novel technique, quantitative tibial ultrasonometry (QUS). In a prospective cohort study, we enrolled 290 girls (mean age 12.7 years) and 273 boys (mean age 12.4 years). Radiographs of the left hand and the left index finger were taken with an aluminium reference wedge within the field of exposure. Radiographic absorptiometry on the second middle phalanx at the mid-level (BMD50%) and proximal quarter (BMD25%) was performed with interactive software. Tibial QUS was performed using the SoundScan Compact. Multiple regression analysis showed that SOS correlated significantly with BMD25% for both boys (r = 0.65, P < 0.001) and girls (r = 0.59, P < 0.001), taking into account age and gender. The same applied for the correlation between speed of sound (SOS) and BMD50% in boys (r = 0.62, P < 0.001) and girls (r = 0.67, P < 0.001). Cubic regression between calendar age and BMD25% showed the best fit for both boys (r2 = 0.60) and girls (r2 = 0.60). For BMD50% a difference in regression was found between boys and girls. Quadratic regression gave a satisfactory fit for boys (r2 = 0.61 ) whereas for girls, a cubic relation was best (r2 = 0.59). Overall, there was a significant correlation between BMD25% and BMD50% for boys r = 0.89 and for girls r = 0.91 (both P < 0.001). Our data show a significant correlation between two different bone assessment techniques. In addition, these data suggest that both tibial ultrasonometry and RA are useful techniques in children.

Absorptiometry, Photon↗
PubMed2001

Bone mineral density assessed by phalangeal radiographic absorptiometry before and during long-term growth hormone treatment in girls with Turner's syndrome participating in a randomized dose-response study.

To assess bone mineral density (BMD) in girls with Turner's syndrome before and during long-term treatment with GH, longitudinal measurements using phalangeal radiographic absorptiometry were performed in 68 girls with Turner's syndrome. These previously untreated girls, age 2-11 y, participating in a randomized, dose-response trial, were randomly assigned to one of three GH dosage groups: group A, 4 IU/m(2)/d ( approximately 0.045 mg/kg/d); group B, first year 4 IU/m(2)/d, thereafter 6 IU/m(2)/d ( approximately 0.0675 mg/kg/d); or group C, first year 4 IU/m(2)/d, second year 6 IU/m(2)/d, thereafter 8 IU/m(2)/d ( approximately 0.090 mg/kg/d). In the first 4 y of GH treatment, no estrogens for pubertal induction were prescribed to the girls. Thereafter, girls started with 17beta-estradiol (5 microg/kg body weight/d, orally) when they had reached the age of 12 y. BMD results were adjusted for bone age and sex, and expressed as SD scores using reference values of healthy Dutch girls. At baseline, almost every individual BMD value of bone consisting predominantly of cortical bone, as well as that of bone consisting predominantly of trabecular bone, was within the normal range of healthy girls and the SD scores were not significantly different from zero [mean (SE) 0.38 (0.22) and -0.04 (0.13)]. During 7 y of GH treatment, BMD SD scores showed a significant increase to values significantly higher than zero [mean (SE) 0.87 (0.15) and 0.95 (0.14)]. The increment in BMD SD score of bone consisting predominantly of cortical bone was significantly higher in group C compared with that of the other two GH dosage groups. The pretreatment bone age was significantly negatively related to the increment in BMD SD score. We found no significant influence of spontaneous puberty or the use of low-dose estrogens in the last 3 y of the study period on the increment in BMD SD score during 7 y of GH treatment. In conclusion, most untreated young girls with Turner's syndrome have a normal volumetric BMD. During 7 y of GH treatment with 4, 6, or 8 IU/m(2)/d, the BMD SD score increased significantly.

Absorptiometry, Photon↗
PubMed2000

[Preliminary results of antibiotic resistance monitoring in the Netherlands].

Qualitative tests are used to monitor antimicrobial resistance in bacteria of animal origin in the Netherlands. Quantitative information on trends in resistance is thus not obtained. Moreover, in general a limited panel of antibiotics is tested. The present study describes resistance in zoonotic food-borne pathogens Salmonella, Campylobacter, and Escherichia coli O157 isolated from human clinical cases and from faeces of healthy food animals in 1998 and 1999, as determined with quantitative susceptibility tests. The resistance of the indicator organisms E. coli and Enterococcus faecium isolated from faecal samples of broilers and pigs randomly sampled at slaughterhouses was also determined. For this end, faecal samples from veal calves were sampled in 1996 and 1997 at the three main Dutch veal calf slaughterhouses. In 1998 only a limited number of faecal samples of veal calves were taken at farms. For E. coli and Salmonella the following antibiotics were tested: amoxicillin, amoxicillin-clavulanic acid, piperacillin, cefotaxime, ceftazidime, imipenem, gentamicin, doxycycline, trimethoprim, trimethoprim/sulphamethoxazole, ciprofloxacin, chloramphenicol, florfenicol, carbadox, and flumequine. For E. faecium the following antibiotics were tested: amoxicillin, amoxicillin-clavulanic acid, chloramphenicol, doxycycline, erythromycin, vancomycin, teicoplanin, streptomycin ('high level' > 2000 mg/ml), gentamicin ('high level' > 500 mg/ml), ciprofloxacin, bacitracin, flavofosfolipol, salinomycin, quinupristin-dalfopristin, virginiamycin, tilmicosin, avilamycin, and everninomycin. For Campylobacter the following antibiotics were tested: erythromycin, doxycycline, gentamicin, carbadox, flavofosfolipol, ciprofloxacin, trimethoprim/sulphamethoxazole, amoxicillin, and metronidazole.

Animals↗
PubMed2000

Radiographic absorptiometry of the middle phalanx (digit II) in a Caucasian pediatric population: normative data.

The availability of improved therapies for children with diseases affecting bone growth and/or metabolism has caused increased interest in bone mineral density (BMD) assessment. The purpose of this study was to determine normal values for phalangeal radiographic absorptiometry (RA) in a Caucasian pediatric population. Five hundred and seventy-two healthy Caucasian children and adolescents (aged 5-19 years) were enrolled in this study. For RA one posteroanterior exposure of the left hand and one lateral exposure of the left index finger were taken. All films were analyzed, yielding BMD (mg Al/mm3) values for two phalangeal sites: one at the proximal quarter of the phalangeal length (BMD25%) and the second at the midpoint of the phalangeal length (BMD50%). Also skeletal age (SA) was assessed, as data normalized for SA can be used in populations which show a dissociation between SA and calendar age. We found that the BMD25% was significantly higher in girls than in boys for the SA group 11-14 years. The BMD50% was significantly higher in girls than in boys for the SA group 11-15 years. Our data show that BMD25% remains fairly constant until the SA of 12.0 years in boys and 10.1 years in girls; after these skeletal ages BMD shows a sharp increase. The same applies to BMD50%, which remains fairly constant until the SA of 12.4 years in boys and 10.7 years in girls. In this paper we present normative data for RA in a pediatric population. These data normalized for skeletal age could be implemented in a clinical setting.

Adolescent↗
PubMed2000

Clonal dissemination of epidemic methicillin-resistant Staphylococcus aureus in Belgium and neighboring countries.

OBJECTIVES: To determine the diversity of pulsed-field gel electrophoresis (PFGE) types among epidemic strains of methicillin-resistant Staphylococcus aureus (MRSA) recovered in Belgium, France, Germany and The Netherlands over the period 1981-94. METHODS: MRSA strains collected in a multicenter survey in Belgium (n = 171) and from reference laboratories in neighboring countries (n = 102) were characterized by PFGE analysis using the SmaI enzyme. RESULTS: In total, 32 PFGE types were found. Epidemic PFGE type 1, first recognized in 1984, accounted for 82% of Belgian strains (87% of hospitals) and 51% of European MRSA strains. Four other internationally epidemic PFGE types (types 8, 10, 11 and 12) were less widely disseminated and more recently detected (1991-94), each recovered from two or three countries. International spread of two PFGE types was linked to transfer of colonized patients to Dutch hospitals from another country where this type was frequently recovered. CONCLUSIONS: Genotypic analysis indicated widespread distribution of several outbreak-associated MRSA strains over large European regions, which was in some instances related to interhospital patient transfer. These findings underscore the need for standardized international surveillance and control of MRSA transmission between healthcare institutions across Europe.

Bacteriophage Typing↗
PubMed2000

Beta-haemolytic streptococci isolated from acute sore-throat patients: cause or coincidence? A case-control study in general practice.

As beta-haemolytic streptococci can be cultured in people with and in those without a sore throat, a case-control study was set up in 43 family practices in The Netherlands. The association was tested between the number of colony counts, specific T/M types and exotoxin genes and an acute sore throat. Duplicate throat swabs were taken from 663 sore-throat patients, selected by clinical criteria, and from 694 healthy controls. They were cultured for beta-haemolytic streptococci by combining several updated laboratory methods. Approximately 40% of the controls and 80% of the patients had beta-haemolytic streptococci-positive cultures. When focusing on cultures with high colony counts, not only group A (46%), but also non-group A streptococci (20%), predominated significantly in adult patients compared with controls. No T/M or exotoxin gene type was significantly more prevalent in patients than in controls. Thus, semiquantitative analysis, but not T/M and exotoxin gene typing, showed an association between beta-haemolytic streptococci and active disease. Groups A, C and G streptococci were found to be potentially pathogenic in adult sore-throat patients, and should be included in the discussion on the use of rapid antigen detection tests and penicillin treatment in primary care.

Acute Disease↗
PubMed2000

Invasive group A streptococcal disease in the Netherlands: evidence for a protective role of anti-exotoxin A antibodies.

As part of a nationwide surveillance in The Netherlands during 1994-1997, 53 patients with invasive group A streptococcal (GAS) infections were evaluated for medical history, symptoms, and outcome. Patients' isolates were tested for the production of pyrogenic exotoxins A (SPE-A) and B (SPE-B). Acute-phase sera from all patients and convalescent sera from 12 patients were investigated for the presence of antibodies against SPE-A and SPE-B. Twenty-three patients developed toxic shock-like syndrome and 16 died. Absence of antibodies against SPE-A and/or SPE-B was a risk factor for developing invasive streptococcal disease. Toxic shock and mortality were associated with a lack of anti-SPE-A antibodies (P<.025). Anti-SPE-A antibodies were found in convalescent sera from all patients infected by speA-positive isolates. Virtually all invasive speA-positive streptococci expressed SPE-A protein in vitro. Thus antibodies against SPE-A appeared vital for mediating the outcome of invasive GAS disease in this population.

Adolescent↗
PubMed1999

Isolation and characterization of verocytotoxin-producing Escherichia coli O157 from slaughter pigs and poultry.

Rectal contents and tonsils from Dutch slaughter pigs collected immediately after slaughter were examined for the presence of verocytotoxin (VT)-producing Escherichia coli (VTEC) of serogroup O157 (O157 VTEC). In addition, fresh fecal material from poultry layer flocks and turkey flocks collected on poultry farms was examined for the presence of O157 VTEC. E. coli O157 strains were isolated from two (1.4%) of 145 pigs. The strains were isolated from samples of rectal contents, all samples of tonsils being negative. While all 501 fecal samples from chicken flocks were found negative, E. coli O157 strains were isolated from six (1.3%) of 459 pooled fecal samples from turkey flocks. One of the porcine isolates and one of the turkey isolates contained the VT2 gene, the E. coli attaching-and-effacing gene, as well as the enterohemorrhagic E. coli hemolysin gene. Production of VT was confirmed by cytotoxicity tests on Vero cells. Based on these characteristics, the two stains were regarded as potentially pathogenic for humans. The porcine and the turkey isolate were further characterized as being of phage types 4 and 14, respectively. While biochemically typical of E. coli O157, the remaining six isolates were nonverocytotoxigenic and negative for both the E. coli attaching-and-effacing gene and the enterohemorrhagic E. coli hemolysin gene. All eight E. coli O157 isolates did not carry genes that encode E. coli heat-labile and heat-stable enterotoxins. It was concluded that pigs and poultry can be a source of O157 VTEC strains characteristic of those causing illness in man. The extent to which pigs and poultry play a role in the epidemiology of human O157 VTEC infection needs further research.

Abattoirs↗
PubMed1999

[Cold tap water as a source of fatal nosocomial pneumonia due to Legionella pneumophila in a rehabilitation center].

OBJECTIVE: Report of the technical, microbiological and epidemiological investigation following 2 cases of fatal Legionella pneumonia. DESIGN: Descriptive. METHOD: Faced with 2 nosocomial cases in a rehabilitation centre in the South of Limburg, the Netherlands, the water supply was investigated. Water temperatures from different taps were measured. Legionella cultures were made from respiratory patients' specimens, water samples and smears from all mixing taps (used in showers), samples from hot and cold water taps from the infected ward and from the five other wards. The strains were typed by serotyping and polymerase chain reaction. RESULTS: The circulating cold water sometimes warmed up to 40 degrees C (within the Legionella growth range). From the sputum of the 2 male patients with rheumatoid arthritis who died of Legionella pneumonia the same Legionella pneumophila (serotype I) was cultured as from the water supply. Of the showers on the contaminated ward 19% (12/63) were positive for Legionella as were 59% (35/59) of the cold water taps. Cultures from the hot water supply were negative just like control cultures from five other wards and swabs from showerheads and hoses. The cold water tubes ran next to the hot water tubes and the central heating system in the same shaft. On the infected ward patients were absent during the weekends. As one of the subsequent measures, the cold water pipes were relocated to another shaft. CONCLUSION: The combination of an elevated cold water temperature caused by heating along a distance by nearby hot water and heating piping and the regular stasis of water during the weekends when the ward was closed, most probably stimulated the multiplication of Legionella in the water supply. In order to minimize contamination of cold water its temperature must be kept below 20 degrees C. Surveillance of intramural water systems is necessary to prevent nosocomial infections.

Cold Temperature↗
PubMed1999

[Secondary infection with methacillin resistant Staphylococcus aureus in Dutch hospitals (July 1997-June 1996].

OBJECTIVE: To study the spread of methicillin-resistant Staphylococcus aureus (MRSA) in hospitals, especially secondary MRSA infections in relation to the origin of the MRSA strain and the measures taken regarding contact isolation. DESIGN: Secondary data analysis. METHODS: As part of the national MRSA surveillance of the National Institute of Public Health and the Environment, data were collected using questionnaires. The analysis covered the period July 1994-June 1996 and was performed for index cases of secondary infections versus sporadic cases. Possible risk factors were determined. RESULTS: In the study period 30 index cases of (clusters of) secondary infections and 191 sporadic cases were found. The size of the clusters was limited. Strict contact isolation as described in the guidelines of the Dutch Working Group on Infection Prevention prevented secondary infections in most cases. Patients for whom no relation could be found between the MRSA infection and a stay abroad were found to have caused more secondary infections, even when the data were corrected for contact isolation measures.

Cross Infection↗
PubMed1999

A Streptococcus pyogenes outbreak caused by an unusual serotype of low virulence: the value of typing techniques in outbreak investigations.

OBJECTIVES: To investigate and stop the spread of an outbreak of Streptococcus pyogenes infection in a district general hospital, involving 19 patients and two nurses over a 20-day period. METHODS: All suspected persons were investigated using conventional bacteriological techniques, followed by M, T and exotoxin gene-typing of the isolates in a national reference laboratory. RESULTS: 11 patients and both nurses were associated with the acute surgical ward on one floor of the hospital. They were infected with serotype M 9/T B3264, a strain with apparently low virulence, which has not been previously associated with outbreaks. Two other patients on the same floor each had different types and there were two clusters of another S. pyogenes serotype on other floors, each involving two patients. Two (unrelated) patients yielded other types of S. pyogenes. The patients were not seriously ill but had some delay in wound healing. CONCLUSIONS: The value of typing the isolates of S. pyogenes in this outbreak was in defining which patients were involved. No added value could be ascribed to the exotoxin gene-typing results.

Adult↗
PubMed1999

Phages for methicillin-resistant Staphylococcus aureus: an international trial.

An internationally agreed and validated set of phages is used worldwide for the typing of strains of Staphylococcus aureus of human origin. However, because of the sometimes reduced susceptibility of methicillin-resistant strains (MRSA) to these phages, some of the national typing centres use locally isolated and characterized sets of experimental phages. In this trial, 42 such phages were distributed to 6 centres and tested against 744 isolates of MRSA with the intention of defining a phage set to augment the international set. The use of these experimental phages increased the percentage typability from 75% with the international set to 93% and the number of identifiable lytic patterns from 192 to 424. A subset of 10 experimental phages was selected. When this subset was compared with the experimental panel, the typability rate was 91% and 370 distinct patterns were obtained. This subset of phages has been distributed for international trial.

Bacteriophage Typing↗
PubMed1998

Resistance of staphylococci in The Netherlands: surveillance by an electronic network during 1989-1995.

An electronic surveillance network for monitoring antibiotic resistance in The Netherlands has been in operation since 1989. Seven public health laboratories participate and the system covers about 25% of all bacteriological determinations in The Netherlands. This paper reports the results of staphylococci isolated in the period 1989-1995. About 0.3% of the Staphylococcus aureus isolates in the study period were resistant to methicillin. This low percentage may be due to the restrictive use of antibiotics and to strict isolation measures aimed at eradicating methicillin-resistant S. aureus. Low frequencies of resistance among methicillin-resistant S. aureus were found for vancomycin (0%), chloramphenicol (11%), cotrimoxazole (11%), mupirocin (3% low-level resistance) and fusidic acid (7%). Twenty-one percent of the coagulase-negative staphylococci were resistant to methicillin. Low frequencies of resistance among these methicillin-resistant coagulase-negative staphylococci were those to vancomycin (0.4%), nitrofurantoin (2%), doxycycline (20%) and amikacin (20%). Coagulase-negative staphylococci from cerebrospinal fluid, blood and skin were less often resistant to quinolones than isolates from respiratory tract, faeces and urine. A significant increase in resistance of coagulase-negative staphylococci to methicillin, erythromycin, gentamicin and ciprofloxacin was observed in the investigated period but the resistance to doxycycline and co-trimoxazole decreased in the last few years. To confirm the determination of methicillin resistance and coagulase production, a PCR method was developed which detects both the mecA and the coagulase gene. The results of the PCR method correlated well with the methicillin MIC as determined by an agar-dilution method.

Anti-Bacterial Agents↗
PubMed1997

Toxic shock syndrome without rash in a young child: link with syndrome of hemorrhagic shock and encephalopathy?

A diffuse macular erythroderma and subsequent desquamation after 1 to 2 weeks are two of the five major diagnostic criteria of toxic shock syndrome (TSS). We present the case of a 15-month-old girl with TSS, but without erythroderma or desquamation. She was admitted with high fever, shock, and multiorgan involvement. Minimal or no cutaneous signs were present. Initially the diagnosis of the syndrome of hemorrhagic shock and encephalopathy was made. After 7 days, a TSS toxin 1-producing strain of Staphylococcus aureus was cultured from an inguinal lymph node, where inflammation had already been noticed on admission. Moreover, the girl had no antibodies against this toxin. The serum cytokine profile during the acute phase of her illness showed high levels of tumor necrosis factor-alpha, interleukin-6 and interferon-gamma, as is seen during activation of the immune system by TSS toxin 1. Other possible causes for the patient's illness were excluded. We conclude that the patient had TSS without rash. Without the evidence implicating a TSS toxin 1-producing strain of S. aureus as the cause of her disease, a diagnosis of syndrome of hemorrhagic shock and encephalopathy would have been made. It is possible that some cases of syndrome of hemorrhagic shock and encephalopathy represent a variant of TSS in small children.

Bacterial Toxins↗