Epidemiology of bacterial endocarditis in The Netherlands. I. Patient characteristics.

BACKGROUND: Studies of the epidemiology of bacterial endocarditis are usually based on a retrospective review of medical records from referral centers serving diverse patient populations. These studies are therefore likely to suffer from selection bias. We conducted a nationwide prospective epidemiologic study of endocarditis in the Netherlands. METHODS: During a 2-year period, all cases of consecutively hospitalized patients with suspected endocarditis in the Netherlands were reported to us. While hospitalized, patients were visited for an in-person interview and a review of the medical record. RESULTS: Of 559 episodes, 438 met the criteria for endocarditis; these included 89 episodes of prosthetic valve endocarditis and 349 episodes of native valve endocarditis. Adjusted for age- and sex-specific population figures, the incidence was 19 per million person-years. The incidence increased significantly with age, and men were more often affected than women (266 and 172 cases, respectively). Rheumatic and congenital cardiac lesions formed most of the underlying heart diseases. Mitral valve prolapse was present in only 29 patients with native valve endocarditis (8.3%). A history of intravenous drug abuse was present in 32 patients (7.3%). Viridans streptococci, staphylococci, and enterococci together constituted 86% of the isolated bacterial strains. Only 1.1% of the patients had culture-negative endocarditis. Overall case fatality was 19.7% and varied widely according to causative microorganism. CONCLUSION: The distribution of causal microorganisms, the case fatality rate, and the incidence rate of endocarditis are age related. Therefore, a meaningful comparison of data is only possible between population-based cohorts of patients with endocarditis.

Epidemiology of bacterial endocarditis in The Netherlands. II. Antecedent procedures and use of prophylaxis.

BACKGROUND: The reported frequency with which endocarditis is ascribed to an antecedent dental or medical procedure varies from 3% to 62%. METHODS: We performed a nationwide prospective study of the epidemiology of bacterial endocarditis in the Netherlands. During a 2-year period, all consecutively hospitalized patients suspected of having endocarditis were visited while still hospitalized for a review of the medical record and an in-person interview that focused on antecedent procedures and administered prophylaxis. All information was checked with pharmacists and dental and medical practitioners. RESULTS: Of 427 patients with late prosthetic or native valve endocarditis, 275 were eligible for antibiotic prophylaxis because of a previously known cardiac lesion (n = 197) or a prosthetic valve (n = 78). Of these 275 patients, 64 (23.3%) had undergone a procedure with an indication for prophylaxis within 180 days of onset; in 31 (11.3%) the procedures had been within 30 days of onset. Antibiotic prophylaxis had been administered to 17 (26.6%) of the 64 patients and to eight (25.8%) of the 31 patients. CONCLUSION: The results indicate that medical and dental procedures cause only a small fraction of endocarditis. The majority of patients develop the disease along other routes. For an incubation period of 180 days, full compliance with prophylaxis might have prevented endocarditis in 47 (17.1%) of 275 patients with late prosthetic or native valve endocarditis involving a previously known cardiac lesion who underwent a procedure with an indication for prophylaxis. For an incubation period of 30 days, prophylaxis might have prevented endocarditis in 23 (8.4%) of these 275 patients, or 5.3% of all patients with endocarditis (n = 427).

Prevalence and determinants of glucose intolerance in a Dutch caucasian population. The Hoorn Study.

OBJECTIVE: To study the prevalence and determinants of glucose intolerance in a general Caucasian population. RESEARCH DESIGN AND METHODS: A random sample of 50- to 74-year old Caucasians (n = 2,484) underwent oral glucose tolerance tests. Multiple regression analyses were performed to study the association of 2-h postload plasma glucose values with potential determinants. RESULTS: Prevalence of known and newly detected diabetes and impaired glucose tolerance was 3.6, 4.8, and 10.3%, respectively. In women, but not in men, the association of body mass index with 2-h glucose was fully accounted for by the waist-to-hip ratio. Maternal history of diabetes was twice as prevalent as paternal history, but paternal history only was associated with 2-h glucose. In addition, paternal history was a stronger determinant in men than in women. An independent positive association with 2-h plasma glucose was found for alcohol use of > 30 g/day in women and for intake of total protein, animal protein, and polyunsaturated fatty acids in men. An independent inverse association with 2-h plasma glucose was demonstrated for height (both sexes), alcohol use of < or = 30 g/day (both sexes), energy intake (in men), and, unexpectedly, current smoking (in men). CONCLUSIONS: The prevalence of diabetes in elderly Caucasians was 8.3%. In men, dietary habits may unfavorably influence glucose tolerance independent of obesity.

Determinants of bone mineral density and risk factors for osteoporosis in healthy elderly women.

Bone mineral density (BMD) and risk factors for osteoporosis were assessed in 348 apparently healthy women over 70 years of age (mean 82.3 years). BMD was measured at both hips and the dominant distal radius. With stepwise multiple regression the best determinants of BMD, selected from anthropometric measurements, age, and years since menopause, were body weight and years since menopause (R2 between 0.07 and 0.20, p < 0.001). Risk and protective factors for osteoporosis were analyzed as indicator variables by multiple regression and corrected for confounding by age, years since menopause, and body weight. Significantly lower BMD at the hip was found in participants with impaired mobility (-5%) and users of loop diuretics (-5%). Use of thiazide(like) diuretics did not influence BMD significantly at any site. Users of oral corticosteroids had a significantly lower BMD at the hip and the distal radius (range -9.1 to -24.3%). Participants with a history of Colles' fracture (n = 56) had a significantly lower BMD at the other radius (-12.9%). The mean calcium intake from dairy products was high (mean 921 mg/day), only 11% having an intake below 500 mg. A relation of calcium intake with BMD could not be detected at any measurement site. We conclude that BMD cannot be adequately predicted in elderly women. Risk factors for low BMD in the elderly are low body weight, high number of years since menopause, impaired mobility, and use of loop diuretics and oral corticosteroids. Calcium intake was not a risk factor in this study, but the number of individuals on a low calcium intake was small.

Serum gonadotropins and alpha-subunit decline in aging normal postmenopausal women.

In a group of 680 postmenopausal women participating in a population survey we investigated the relationships between serum gonadotropin, alpha-subunit and PRL concentrations and age, body mass index (BMI), and levels of sex hormone-binding globulin, estrogens, and androstenedione. Gonadotropin and alpha-subunit levels were negatively correlated with age, while PRL levels did not decrease with age. Regression means of serum concentrations in women aged 55 to 75 yr, respectively, decreased for LH from 47.1 to 32.4 IU/L, for FSH from 72.1 to 61.6 IU/L, and for alpha-subunit from 2.6 to 1.9 micrograms/L. The ratio of alpha-subunit to LH and FSH decreased with age. These changes may be caused by either a direct effect of aging on pituitary gonadotroph cells or an effect of aging on the hypothalamic regulation of these cells. Serum gonadotropin and alpha-subunit concentrations were negatively correlated with the BMI, but not with circulating estradiol levels. In addition, we found that estrone and estradiol levels were positively correlated with the BMI, while circulating levels of androstenedione and estrone were more important factors, determining estrone and estradiol levels, respectively. In conclusion, in contrast to what has been reported in normal aging men, serum LH, FSH, and alpha-subunit concentrations decrease with age in normal postmenopausal women.

Long-term effects of neonatal sodium restriction on blood pressure.

In 1980, a randomized trial was conducted among 476 Dutch newborn infants to study the effect of a low or normal sodium diet on blood pressure during the first 6 months of life. At the end of the trial, systolic blood pressure in the low sodium group (n = 231) was 2.1 mm Hg lower than in the control group (n = 245). To investigate whether contrasting levels of sodium intake in infancy are associated with blood pressure differences in adolescence, we measured blood pressure in 167 children from the original cohort (35%) after 15 years of follow-up. We assessed the differences in systolic and diastolic blood pressure levels between the diet groups using a multivariate regression model with adjustment for potential confounders. The adjusted systolic blood pressure at follow-up was 3.6 mm Hg lower (95% confidence interval, -6.6 to -0.5) and the diastolic pressure was 2.2 mm Hg lower (95% confidence interval, -4.5 to 0.2) in children who had been assigned to the low sodium group (n = 71) compared with the control group (n = 96). These findings suggest that sodium intake in infancy may be important in relation to blood pressure later in life.

Serum selenium, vitamin antioxidants, and cardiovascular mortality: a 9-year follow-up study in the Netherlands.

The association between low serum selenium, vitamin A, and vitamin E levels and mortality from cardiovascular disease (CVD) was investigated in a case-control study nested in a 9-yr prospective study in the Netherlands. For 10,532 persons aged greater than or equal to 5 yr who participated in a 1975-1978 medical survey, serum was stored at -20 degrees C. For the 84 of 106 subjects aged 37-87 yr who died of CVD after the baseline exam, 168 cohort members alive at the end of 1983 and matched for age and gender were selected as controls. No significant associations between serum selenium. vitamin A, vitamin E, and CVD mortality were observed before and after multivariate analyses. The adjusted risk of death from CVD for subjects in the lowest selenium quintile (less than 105.0 micrograms/L) was 1.6 (95% CI, 0.8-3.2). For coronary and stroke death risk, estimates were 1.1 (95% CI, 0.5-2.6) and 3.2 (95% CI, 0.8-12.1). Our findings do not show a clear CVD risk from low selenium and vitamin levels. Although some of the risk estimates were strong, larger studies are required for definitive conclusions.

Characteristics and determinants of sumatriptan-associated chest pain.

BACKGROUND: Serious cardiac adverse reactions, including myocardial infarction, have been attributed to the antimigraine drug sumatriptan succinate. Chest pain is considered to be a relatively common adverse reaction to sumatriptan. DESIGN: Postmarketing study. PATIENTS AND METHODS: The study was a part of a national cohort study on adverse reactions to sumatriptan, which was performed with the assistance of drug-dispensing general practitioners in the Netherlands. After data were collected on observed adverse reactions, the patients received a second questionnaire, with specific questions regarding the adverse event, and questions regarding medical history, other health complaints, and smoking habits. Furthermore, they had a physical examination and a blood cholesterol measurement. RESULTS: A total of 137 patients with chest pain associated with intake of sumatriptan were identified and compared with 229 consumers of sumatriptan without this adverse reaction. After multivariate analysis, young age, hypertension, general complaints of abdominal pain, and a family history of myocardial infarction were associated with an increased risk of chest pain attributed to sumatriptan. Hypertension in particular was a risk factor for sumatriptan-induced chest pain in men (relative risk, 8.0; 95% confidence interval, 1.8-40) compared with hypertension as a risk factor in women (relative risk, 1.63; 95% confidence interval, 0.9-3.1). CONCLUSIONS: Young age, hypertension, general complaints of abdominal pain, and a family history of myocardial infarction are associated with an increased risk of chest pain attributed to sumatriptan. Sex is an effective modifier of risk factors of sumatriptan-induced chest pain. In particular, hypertension is a strong risk factor in men.

Sodium restriction and potassium supplementation in young people with mildly elevated blood pressure.

Forty young subjects, aged 18 to 28 years, with mildly elevated blood pressure participated in a double-blind randomized three-period crossover study of the effect of sodium restriction with and without potassium supplementation on blood pressure. Dietary sodium intake was restricted for 18 weeks in which the patients received in random sequence 'slow-sodium' (90 mmol/day), 'slow-potassium' (72 mmol/day), and placebo tablets, each for 6 weeks. Mean urinary sodium excretion was 129 mmol/24 h in the slow-sodium period, 57 mmol/24 h during placebo, and 69 mmol/24 h during slow-potassium. Mean supine systolic blood pressure in the sixth week of the slow-potassium period was 3.3 mmHg lower than that at the end of the slow-sodium period (P less than 0.05). There was no significant difference in systolic or diastolic blood pressure between the placebo and the slow-sodium periods. The fall in systolic blood pressure in the low sodium/high potassium period was accompanied by a fall in cardiac index of 0.4 l/min per m2 body surface area (BSA) (P = 0.03). Our observations suggest a small hypotensive effect of moderate sodium restriction combined with high potassium intake in young hypertensive subjects. Sodium restriction alone has little effect on blood pressure in this group. The combination of a low sodium/high potassium diet may lower blood pressure by affecting cardiac output. Reducing the dietary sodium:potassium ratio may therefore be useful in the management of early primary hypertension.

The lifetime cumulative incidence of acute anterior uveitis in a normal population and its relation to ankylosing spondylitis and histocompatibility antigen HLA-B27.

The lifetime cumulative incidence of acute anterior uveitis (AAU) was determined in a sample of a large population (n = 10,500). Nine hundred seventeen subjects, who answered the question "Have you ever had a red eye" in the affirmative in 1977, were asked to participate in a follow-up study 10 years later. From the 917 respondents, 539 were studied completely. A questionnaire was used to collect historic data, and confirmation of these data was obtained from the treating ophthalmologists and physicians. From these data, subjects were selected for an ophthalmologic examination. The respondents also underwent a rheumatologic examination. The results revealed that the lifetime cumulative incidence of definite AAU is approximately 0.2% in the general population and 1% in the histocompatibility antigen HLA-B27-positive population. In one third of the definite AAU patients, the cause of the disease was known. The lifetime cumulative incidence of definite AAU of unknown cause was 0.15% in the general population. When possible and probable AAU are included, the lifetime cumulative incidence of AAU in the general population is about 0.4%. The observed frequency of the concurrence of AAU and ankylosing spondylitis (AS) was 0.4% in the HLA-B27-positive population and 0.02% in the HLA-B27-negative population. Comparison with the expected frequency of the concurrence of AAU and AS revealed that AAU and AS probably are related diseases irrespective of the association of both diseases with HLA-B27.

Low vitamin B6 status in patients with acute myocardial infarction.

The vitamin B6 status of 84 patients with acute myocardial infarction was compared with that of 84 control subjects. Pyridoxal and pyridoxal 5'-phosphate (PLP) in plasma and erythrocytes, as well as the basal and total potential activity of the PLP-dependent enzyme aspartate aminotransferase in erythrocytes, were measured for a comprehensive assessment of vitamin B6 status. The mean levels of all vitamin B6 indexes (except pyridoxal) were lower in the patients than in the control subjects. The differences were statistically significant, except for erythrocyte PLP and total potential enzyme activity. The adjusted relative odds of a myocardial infarction for subjects in the lowest quartile of plasma PLP was about 5 times higher when compared with those in the highest quartile (relative odds = 5.2, 95% confidence interval = 1.4 to 18.9). Similar findings were found with the other vitamin B6 indexes. No significant association between infarct size, as estimated by creatine kinase level, and the vitamin B6 indexes was observed.

Epidemiological and clinical aspects relating to the variability of rheumatoid arthritis.

OBJECTIVE: To review epidemiological studies dealing with the temporal and geographic variability in the occurrence of rheumatoid arthritis (RA) and clinical studies that address the variability of severity and manifestations among populations. METHODS: An extensive search of the literature, including a Medline search, was completed. Studies addressing the origin, history, and trends in the occurrence of RA were reviewed first. Next, studies of the prevalence and incidence of RA in different populations were reviewed, and occurrence rates compared. Standardization was attempted by tabulating adult prevalence rates of studies using equivalent sets of criteria. Studies comparing RA patients from two populations were sought next. Finally, studies dealing with explanations of the presumed variability were reviewed. RESULTS: Temporal variability is indicated by paleopathological evidence that RA has existed in the New World since 4000 BC, whereas there is no evidence that it occurred in Europe before the 17th century, or in Africa before the 20th century. Epidemiological studies show a possible trend of decreasing incidence of RA in the United States and Western Europe, whereas reports from Africa note a rising incidence. In white populations of Europe and America, prevalence is approximately 1%, and incidence is 0.03%. Significantly higher rates are found in some North American Indians, and significantly lower rates in some Asian and African populations, even when the different population structures are taken into account. In the latter populations, different patterns of occurrence from those observed in whites emerge, such as greater female preponderance and a much younger peak age at onset. Direct standardized comparisons of two diverse populations of RA patients showed some differences in expression, severity, or manifestations of RA between populations. CONCLUSION: The occurrence and manifestations of RA are temporally and geographically variable.

Genetic heterogeneity of rheumatoid arthritis.

In a population survey in The Netherlands we investigated 6584 individuals for the presence of rheumatoid diseases and their determinants. We observed no overall association of rheumatoid arthritis (RA) with HLA-DR4 or GM. This result is in contrast to the marked association of HLA-DR4 with RA found in studies based mainly on hospital rheumatology clinics. The findings thus suggest a genetic basis for the disease heterogeneity. A study of 16 multicase RA families showed a co-segregation of RA with the DR4 carrying haplotype from the unaffected parent, whereas the non-DR4 haplotype was preferentially segregating to the healthy siblings (p = 0.001). These data suggest that HLA-DR4 is associated with disease susceptibility rather than with a disease modifying factor. In a further attempt to define a genetic basis for disease heterogeneity we compared five well-defined clinical groups of patients with RA. Although the frequency of HLA-DR4 was significantly elevated in all patient groups as compared to healthy controls, we observed a preferential association of HLA-DR4 with severe extra-articular manifestations as compared to patients without extra-articular manifestations (p = 0.002). These results provide an immunogenetical basis for the disease heterogeneity observed in RA and further extend the immunological analogy between RA and leprosy.

Metacarpal bone loss in middle-aged women: "horse racing" in a 9-year population based follow-up study.

Differences in the rate of metacarpal bone loss were evaluated in a 9 year population based follow-up study among 799 women initially aged 45-64 years, using initial and follow-up radiographs of the hands. Metacarpal bone loss started around the age of 50 years and was present in more than 95% of the women. The average annual rate of loss was approximately 1% of the initial value. The prevalence of osteopenia increased from 5% for women aged 45-49 years, up to 68% for women aged 70-76. The rate of bone loss was not similar for each individual. Regression analyses of rate of change-in-RCA on initial level of RCA indicated the presence of a consistent subgroup of fast bone losers. However, osteopenia at follow-up was more accurately predicted from initial bone density than from differences in the rate of loss.

Differences in perceived and presented adverse drug reactions in general practice.

BACKGROUND: Postmarketing surveillance (PMS) studies are frequently based on data from general practitioners (GPs). Patients, however, do not always report to their GP suspected adverse drug reactions. SETTING: A postmarketing cohort study on adverse reactions to sumatriptan, performed with assistance of drug dispensing GPs in The Netherlands. METHODS: Questionnaires were sent to all drug-dispensing GPs in The Netherlands, as well as to their patients on sumatriptan. To avoid bias, no specific adverse reactions were mentioned in the questionnaires. RESULTS: Of the GPs, 589 (86%) responded; of the patients, 1202 (70%) responded. The most frequently reported suspected adverse reactions to sumatriptan reported by the GPs were dizziness (1.7%), nausea or vomiting (1.5%), drowsiness or sedation (1.4%), and chest pain (1.3%). The most frequently reported suspected adverse reactions by the patients were paraesthesia (11.7%), dizziness (8.1%), feeling of heaviness (8.0%), and chest pain (7.9%). Neither the GPs nor the patients reported serious adverse reactions. CONCLUSIONS: First, patients experience significantly more suspected adverse reactions than are registered by their GP. In view of this higher frequency of reporting of suspected adverse reactions, postmarketing studies with data from GPs only, may underestimate the cumulative incidence of adverse reactions. Second, we conclude that it is possible to obtain useful additional information about adverse drug reactions from patients by sending them questionnaires via their GP.

The natural history of blood pressure in childhood.

To find out whether there is a relationship between the level of blood pressure in childhood and later on in life, and whether future hypertensives can be identified early in life, we selected a random sample of 596 Dutch children. At the first examination they were 5-19 years of age. In 386 of them (65%) at least five consecutive annual blood pressure measurements were made between 1975 and 1982. The stability of a child's position in the blood pressure distribution ('tracking') was studied by linear regression of follow-up blood pressure on initial blood pressure. 'Tracking' coefficients were 0.4 to 0.6 mmHg/mmHg for systolic pressure, and 0.2 to 0.5 mmHg/mmHg for diastolic pressure after four years of follow-up. Twenty-seven per cent of the boys and 44% of the girls who were in the upper 10% of the systolic blood pressure distribution at the first examination were still there after four years. For diastolic pressure these figures were 25% and 22%, respectively. These observations indicate that there is a moderate degree of blood pressure 'tracking' in childhood. They further imply that it is impossible to detect future hypertensives early in life by measurement of blood pressure only.

Are maternal fertility problems related to childhood leukaemia?

An explorative case-control study was conducted in The Netherlands. The cases were obtained from a complete nationwide register of childhood leukaemia (1973-1980). Controls were matched with the cases for year of birth, sex and place of residence. Information about exposures of the mother to potential risk factors in the year before pregnancy and during pregnancy was collected via mailed questionnaires. The analyses concerned data on 519 patients with acute lymphocytic leukaemia and 507 controls. An association between maternal subfertility and childhood leukaemia might be suggested by several findings. A history of two or more miscarriages (OR 1.6; 95% Cl 1.0-2.7) and fertility problems (OR 6.0; 95% Cl 0.9-38.2) were more frequently reported among mothers of cases. The use of oral contraceptives (OC) was significantly higher (OR 1.3; 95% Cl 1.0-1.8) and the duration between discontinuation of OC and the relevant pregnancy was significantly longer. The OR for threatened abortion during the relevant pregnancy was 1.6 (95% Cl 1.0-2.6) and the related use of 'drugs to maintain pregnancy' was 1.9; 95% Cl 1.0-3.5. Among known risk factors, an increased OR for diagnostic irradiation was confirmed (OR 2.2; 95% Cl 1.2-3.8). No association between childhood leukaemia and prenatal viral infections, smoking and alcohol was found.

Selenium status and chronic disease mortality: Dutch epidemiological findings.

This paper summarizes Dutch epidemiological findings on the impact of a low selenium (Se) status on mortality from cardiovascular disease (CVD) and cancer. Se status parameters of Dutch subjects are compared to those from Finland and the USA, and the concept of a threshold effect for Se on disease risk is discussed. Case-control analyses of prospective data suggest that low serum Se (below 105 micrograms/l) is not clearly associated with an excess risk of CVD death (relative risk RR = 1.6, 90% confidence interval Cl = 0.9-2.9). Se cancer findings indicate a possible gender difference in risk (in males RR = 2.7, 90% Cl = 1.2-6.2; in females RR = 1.5, 90% Cl = 0.5-4.5). Larger studies, monitoring a combination of Se status parameters are recommended.

Lipo-oligosaccharide immunotyping of Neisseria meningitidis by a whole-cell ELISA with monoclonal antibodies.

To assess the applicability of a whole-cell ELISA (WCE) with monoclonal antibodies (MAbs) for lipo-oligosaccharide (LOS) immunotyping of Neisseria meningitidis, 675 meningococcal isolates obtained in 1989 and 1990 in the Netherlands and 57 isolates collected in 1974, of which the immunotype had been determined previously by microprecipitation, were analysed. Despite the lack of specific MAbs for L2 and L4, an algorithm was developed for the assignment of immunotypes on the basis of the reaction patterns of the reference strains and these isolates to a combination of 14 MAbs. The immunotypes found by WCE were in accordance with those obtained by microprecipitation and the results from WCE were reproducible. The distribution of immunotypes among isolates of the various serogroups in the Netherlands in 1989-1990 is presented. Based on the reaction patterns of the isolates, two main categories of related immunotypes could be distinguished among isolates of serogroups B and C: L2/L4 and L3/L1/L8. Some isolates of the latter category were of one immunotype, but many isolates expressed one or two additional immunotypes, either strongly or weakly, indicating that the differences in this category are quantitative rather than qualitative. The results of this study have demonstrated that the WCE method for LOS immunotyping is easily applicable and provides better definition of test strains for in-vitro bactericidal assays and research into pathogenesis.

Faecal carriage of aerobic gram-negative bacilli and drug resistance of Escherichia coli in different age-groups in Dutch urban communities.

Faecal carriage rates for aerobic gram-negative bacilli and for antibiotic-resistant Escherichia coli were determined in samples of the Dutch urban population. Of the 741 people studied, 64 were under 1 year old (infants), 53 were 1-5 years old, and there were approximately 200 in each of the age-ranges 6-17 years, 18-49 years and 50-80 years. Carriage rates of E. coli were similar (87-93%) in all age groups, but Klebsiella and Enterobacter species were found more often in specimens from infants and young children than in those from older people. E. coli strains resistant to tetracycline, ampicillin, or sulphamethoxazole or to any one or more of them were detected in 42%, 26%, 46% and 66% respectively of the specimens found to contain E. coli. The corresponding figures for the finding of E. coli populations that were predominantly resistant to tetracycline, ampicillin or sulphamethoxazole were 12%, 6% and 20%. The frequency of resistance to any of these drugs was not related to age or sex of the subjects. All E. coli isolates were sensitive to gentamicin. Among the 577 subjects aged 6-80 years from whose samples E. coli was isolated were 19 who had taken antibacterial drugs in the previous 30 days and 11 who were involved in cattle farming; carriage rates for tetracycline-resistant and sulphonamide-resistant E. coli were significantly higher among these 30 than in the other 547.