Risk factors for hospital-acquired Staphylococcus aureus bacteremia.

BACKGROUND: Staphylococcus aureus bacteremia (SAB) acquired in hospitals continues to be a frequent and serious complication to hospitalization, and no previous case-control studies dealing with risk factors of this severe disease are available. METHODS: Based on a 1-year prospective analysis, the data from all patients with hospital-acquired SAB admitted to 4 hospitals in Copenhagen County, Denmark, from May 1, 1994, through April 30, 1995, were evaluated. Eighty-five patients with hospital-acquired SAB were matched to 85 control patients with a similar primary diagnosis at admission (matched controls). Of these, 62 patients with hospital-acquired SAB were compared with 118 other patients with a similar time of admission, who were randomly selected with no clinical evidence of SAB (unmatched controls). RESULTS: The incidence of hospital-acquired SAB was 0.71 per 1000 hospital admissions. The presence of a central venous catheter (odds ratio, 6.9; 95% confidence interval [CI], 2.8-17.0), anemia (odds ratio, 3.3; 95% CI, 1.4-7.6), and hyponatremia (odds ratio, 3.3; 95% CI, 1.5-7.0) was significantly associated with hospital-acquired SAB in a conditional and a usual logistic regression analysis. Nasal carriage was not an independent risk factor, but nasal carriers among patients in surgery (odds ratio, 4.0; 95% CI, 1.3-13.0) had a significantly higher risk for hospital-acquired SAB compared with matched and unmatched controls. The presence of hospital-acquired SAB increased the mortality rate 2.4-fold (95% CI, 1.1-5.2). CONCLUSIONS: The presence of a central venous catheter is an important risk factor, and hyponatremia and anemia are associated with the development of hospital-acquired SAB. Furthermore, hospital-acquired SAB in itself increases mortality.

Patterns and trends in clinically recognized HIV seroconversions among all newly diagnosed HIV-infected homo-/bisexual men in Denmark, 1991-1994.

OBJECTIVE: To analyse patterns and trends in recently acquired HIV infections among newly diagnosed homo-/bisexual men. DESIGN AND METHODS: All newly diagnosed HIV-positive homo-/bisexual men reported to the mandatory national HIV reporting system in Denmark in 1991-1994. RESULTS: A total of 495 homo-/bisexual men were diagnosed with HIV infection for the first time; 45% had previously been tested HIV-negative, among whom 68% were known to have seroconverted 4 years or less prior to the positive diagnosis. Both proportions increased significantly from 1991 to 1994. Among men previously tested negative, the median interval between last negative and first positive HIV test was 902 days (range, 14-4459 days); 21.3% had seroconverted within 1 year and 55.1% within 3 years. Men previously tested negative were significantly younger than men never tested. Sex with a known HIV-positive partner was associated with having had a previous negative test and with being young. Half of the men had HIV-associated symptoms when diagnosed with HIV. Using a logistic regression model the following variables were associated with being a clinically recognized recent seroconverter: young age, no HIV-associated symptoms when diagnosed as HIV-infected, and ever having sex with an HIV-infected man. CONCLUSION: An increasing proportion of homo-/bisexual men diagnosed with HIV in Denmark in the early 1990s had had a negative HIV test 4 years or less before being diagnosed as HIV-positive. These men were younger and had HIV-associated symptoms less often than men not previously tested. The national HIV reporting system provides valuable information for planning primary HIV prevention programmes.

Evaluation of eight commercial kits for Helicobacter pylori IgG antibody detection.

Eight commercial kits and an in-house ELISA for detection of IgG antibodies against Helicobacter pylori were evaluated for their use in diagnosis of H. pylori infection and in epidemiological research: Helico-GTM (Porton-Cambridge), G. A. P. test (Bio-Rad), H. pylori antibodies ELISA (Biometra), Anti-H. pylori IgG EIA (Roche), 2nd generation H. pylori EIA (Roche), Anti-H. pylori MTP-assay (Roche), Pylori stat test kit (Whittaker), Pyloriset latex agglutination kit (Orion), and the in-house ELISA based on heat-stable antigens. Fifty-four patients with dyspepsia (31 H. pylori positive by culture or microscopy) and 68 asymptomatic persons were tested. Sensitivities for the eight kits were 71%, 77%, 90%, 84%, 87%, 94%, 90%, 87%, and 87%, specificities were 74%, 65%, 74%, 74%, 83%, 83%, 70%, 65%, and 65%, respectively. For epidemiological use the estimated seroprevalence varied within approximately 15% in all age groups. Sensitivities and specificities obtained in different studies reveal as great differences in the results with the same kit as between results obtained with different kits in the same study. Kits with the highest sensitivities tend to be the same in all studies. It is therefore more important to test a kit in the population to which it is to be applied than to choose a specific kit.

Immunity from diphtheria, tetanus, poliomyelitis, measles, mumps and rubella among adults in Lithuania.

Health authorities have estimated a low immunity level against diphtheria, tetanus, poliomyelitis, measles, mumps and rubella among adults in Lithuania due to less than optimal vaccine quality. The aim of this study was to evaluate the level of immunity by blood sampling 100 young women, 50 young men and 50 middle-aged men and from the immunization history by questionnaire. Lack of protection against diphtheria was found in 0%, 2% and 46% of the young women, young men and middle-aged men respectively. The corresponding data for tetanus were 0%, 0% and 10%. It was found that 85% of the women had antibodies to all 3 types of polioviruses vs. 80% of the young men and 56% of the middle-aged men. A sub-protective antibody level against measles was found in 12% of the women, 22% of the young men, but in none of the middle-aged men. A protective titre of rubella antibodies was found among 94% of the young, pregnant women. It can be concluded that the level of immunity in Lithuania is comparable to that in Western Europe for the same age groups and that the launching of adult vaccination programs in Eastern Europe should be preceded by sero-epidemiological studies.

Comparison of four second generation kits for detection of IgG antibodies against Helicobacter pylori in adults.

Four serological kits for detection of IgG antibodies against H. pylori were tested on 132 adult patients with dyspeptic symptoms. Presence of H. pylori infection was established when either culture or microscopy of gastric biopsies were positive. The prevalence of H. pylori infection was 55% in the test population. With Anti-H. pylori MTP-assay (Roche), Pylori stat test kit (Whittaker), HM-CAP (Enteric Products Inc.) and Pyloriset EIA-G (Orion) the sensitivities were 97%, 95%, 81% and 68% respectively, the specificities were 53%, 56%, 71% and 69% respectively, the positive predictive values 72%, 74%, 79% and 74% respectively and the negative predictive values were 94%, 92%, 79% and 64% respectively.

Estimation of measles reproduction ratios and prospects for elimination of measles by vaccination in some Western European countries.

The objective of this study is to estimate the measles reproduction ratio for eight Western European vaccination programmes. Because many plausible age-structured transmission patterns result in a similar description of the observations, it is not possible to estimate a unique value of the reproduction ratio. A method is developed to estimate bounds and confidence intervals for plausible values of the reproduction ratios using maximum likelihood methods. Lower and upper bounds for plausible values of the basic reproduction ratio are estimated to be 7.17 (95% CI 7.14-7.20) and 45.41 (95% CI 9.77-49.57), corresponding to lower and upper bounds on critical vaccine coverage of 86.6% and 98.1%. Of the eight evaluated vaccination programmes, four have vaccine coverage below the lower bound and allow measles to persist, and four have vaccine coverage at the upper bound and may eventually eliminate measles.

Proliferative responses to purified and fractionated Bordetella pertussis antigens in mice immunized with whole-cell pertussis vaccine.

The specificity of the cell-mediated immune response to Bordetella pertussis following immunization of C57B1 mice with a whole-cell pertussis vaccine was assessed in a proliferation assay. A proliferative response of lymph node lymphocytes to the filamentous haemagglutinin, the 69 kDa outer membrane protein and the agglutinogens 2 and 3 was demonstrated. The proliferative cells were T cells of the CD4+ phenotype. In addition, several as yet uncharacterized antigens expressed by B. pertussis were shown to induce a proliferative response, also mediated by T cells of the CD4+ phenotype. Although a range of different immunization schedules and preparations of pertussis toxin were used, no specific proliferative responses to pertussis toxin, which is regarded as a protective antigen of major importance from B. pertussis, were found.

Survival of patients with surgical wound infection: a case-control study of common surgical interventions.

A cohort of 4515 surgical patients was selected from ten different surgical intervention groups, and 291 of 317 with a postoperative wound infection were matched 1:1 with controls with regard to intervention, sex and age. The mortality rate was investigated from the time of operation, with a follow-up period from 4 years 4 months to 8 years 4 months. Eighty-seven patients with a deep infection had a significantly increased mortality rate, with a risk ratio of 1.7. Without a distinction between superficial and deep infection the former might mask the higher mortality rate associated with the latter.

Molecular epidemiology of tuberculosis in Denmark in 1992.

The incidence of tuberculosis (TB) is increasing all over the world, including in countries with a high standard of living and good social security. Denmark represents such a region. Furthermore, it is a small country (5 million inhabitants) with a long tradition in TB control, including a centralization of the bacteriological diagnostic facility. The present study was intended to analyze the transmission of Mycobacterium tuberculosis in a country in which TB has low endemicity by a combination of conventional epidemiological approaches and DNA fingerprinting techniques, whereby individual bacterial strains can be traced. M. tuberculosis isolates from 92% of all new cases of bacteriologically verified TB in Denmark during 1992 were subjected to IS6110 DNA fingerprinting to visualize the DNA restriction fragment length polymorphism (RFLP) patterns of the isolated strains. The data obtained from the RFLP analyses were interpreted by using demographic data, such as age, sex, ethnicity, and residence, for the patients. The risk factors among the patients for being part of an active chain of transmission, as opposed to demonstrating reactivation of a previously acquired latent infection, were estimated by statistical analyses. The magnitude of TB transmission in 1992 in Denmark was determined, and transmitted infections were shown to comprise at least one quarter of the total number of cases. Almost half of the TB cases involved patients of foreign origin. However, most of these isolates showed unique DNA fingerprint patterns and were rarely part of an active chain of transmission. The major chains of recent transmission were localized to distinct geographical regions in the country. TB is frequent among immigrants, especially from Asia and Africa, but it is apparently readily suspected, diagnosed, and treated by the health care system. Danish patients with pulmonary symptoms are not primarily suspected to have TB and, therefore, play an important role in recent TB transmission in Denmark.

Immune response to diphtheria booster vaccine in the Baltic states.

A study was done to measure baseline levels of immunity to diphtheria and antibody responses to different doses of diphtheria vaccine in study participants in the three Baltic states. Diphtheria booster vaccines containing either 3 (Estonia and Lithuania), 6 (Latvia), or 12 (Latvia) limit of flocculation units of diphtheria toxoid were administered to 2315 adults. Diphtheria antibody levels were tested before and 1-2 months after vaccination. Before vaccination, 40% of the participants in Estonia, 32% in Lithuania, and 38% in Latvia had antibody levels <0.01 IU/mL, the level for minimum protection. After vaccination, 79% of the participants in Estonia, 83% in Lithuania, and 81% in Latvia had antibody levels >0. 1 IU/mL, the minimum level for full protection. However, in each of the countries, about one-third of the 40- to 49-year-old participants would have benefited from additional doses of vaccine. There was not a significantly different antibody response among persons receiving the three different doses. Age and the level of prevaccination immunity had a modifying effect on the response to vaccination; however, sex did not.