Kamilla D. Lettinga

A large outbreak of Legionnaires' disease at a flower show, the Netherlands, 1999.

In 1999, an outbreak of Legionnaires’ disease affected many visitors to a flower show in the Netherlands. To identify the source of the outbreak, we performed an environmental investigation, as well as a case-control study among visitors and a serologic cohort study among exhibitors to measure exposure to possible sources. Of 77,061 visitors, 188 became ill (133 confirmed and 55 probable cases), for an attack rate of 0.23% for visitors and 0.61% for exhibitors. Two whirlpool spas in halls 3 and 4 of the exhibition and a sprinkler in hall 8 were culture positive for Legionella pneumophila. One of three genotypes found in both whirlpool spas was identical to the isolates from 28 of 29 culture-positive patients. Persons who paused at the whirlpool spa in hall 3 were at increased risk for becoming ill. This study illustrates that whirlpool spas may be an important health hazard if disinfection fails.

Legionnaires' Disease at a Dutch Flower Show: Prognostic Factors and Impact of Therapy

After a large outbreak of Legionnaires’ disease in the Netherlands, we determined risk factors for intensive care unit (ICU) admission and death and the impact of adequate therapy on ICU-free survival among 141 hospitalized patients. Overall mortality rate was 13%, and ICU mortality rate was 36%. Smoking, temperature >38.5°C, and bilateral infiltrates shown on chest x-ray were independent risk factors for ICU admission or death (all p<0.05). Starting adequate therapy within 24 hours after admission resulted in a higher ICU-free survival rate compared to therapy initiation after 24 hours: 78% versus 54%, respectively (p=0.005). However, delay in providing therapy to patients with urinary antigen tests with negative results did not influence outcome. These data suggest that by using the urinary antigen test on admission a more tailored approach to patients with community-acquired pneumonia may be applied.

Detection and quantitation of human cytomegalovirus DNA in faeces

The development and performance of a robust and sensitive PCR assay are described for the detection and quantitation of human cytomegalovirus DNA in human faecal specimens. In this assay, CMV DNA was purified by an optimised DNA extraction protocol together with internal control DNA that monitored both DNA extraction efficiency and PCR efficiency. The lower detection limit of the assay was reached at about 100 CMV particles per ml of (25-50%) faecal suspension. CMV DNA could be quantitated in the range of about 300-100000 molecules per ml of faecal suspension. CMV DNA loads obtained in clinical faeces specimens suggest that the assay can be used to monitor the efficacy of antiviral treatment. Reconstruction experiments that monitored the efficiency of DNA extraction of a preliminary DNA extraction protocol, showed low DNA yields for 9% of the specimens (n = 78). In all cases, low DNA extraction efficiency seemed to be due to a component present in faeces that prevented DNA binding to silica particles, presumably by competitive binding. Choosing the right ratio of silica particles to faeces specimen solved this problem. Similarly, reconstruction experiments showed that the strong PCR inhibition that was observed in 8% of the specimens could effectively be relieved by the inclusion of alpha-casein in the PCR mixtures.

Health-related quality of life and posttraumatic stress disorder among survivors of an outbreak of legionnaires disease

A follow-up study of 122 survivors of an outbreak of legionnaires disease (LD) in The Netherlands was conducted to determine persistence of symptoms, health-related quality of life (HRQL), and presence of posttraumatic stress disorder (PTSD). Seventeen months after diagnosis of LD, survivors completed a questionnaire assessing symptoms and HRQL and a questionnaire assessing PTSD. The most prevalent new symptoms were fatigue (in 75% of patients), neurologic symptoms (in 66%), and neuromuscular symptoms (in 63%). HRQL was impaired in 7 of the 8 dimensions assessed by the HRQL questionnaire, and 15% of patients experienced PTSD. Symptoms and impaired HRQL persisted for >1.5 years. As a result of the design of this study, it could not be inferred whether Legionella pneumophila infection, severe pneumonia in general, or the outbreak situation was responsible for impaired well-being. However, awareness of this problem by health care providers may improve the aftercare of patients.

High cathepsin B activity in arthroplasty interface membranes: A histochemical study of 9 loose cemented total hip prostheses

We studied biopsies of interface membranes of 9 aseptically loosened total hip prostheses. The morphologic resemblance of the cement-facing surface of the membranes to synovial tissue of arthritic joints, as noticed by others, was confirmed by histochemical techniques. High cathepsin B activity was found in the bone-facing surface of the membranes. Since this enzyme also plays an important role in tissue destruction of arthritic joints, further similarities in the mechanisms of tissue breakdown in arthritis and aseptic loosening of cemented hip prostheses may be conjectured.

Deficient mannose-binding lectin-mediated complement activation despite mannose-binding lectin–sufficient genotypes in an outbreak of Legionella pneumophila pneumonia

Polymorphisms leading to deficiency of mannose-binding lectin (MBL) are associated with predisposition to infection. However, MBL deficiency can be protective against intracellular pathogens that use MBL to enter host cells. The role of MBL genotype and activity in infection with the intracellular pathogen Legionella pneumophila was studied in a large outbreak of legionellosis at a Dutch flower show. A total of 141 patients, 65 exposed asymptomatic exhibition staff members and 670 unexposed blood bank donors were included for the study of MBL2 genotypes and MBL-mediated complement activation. Genotypic MBL deficiency was equally prevalent in patients and controls. Deficient MBL-mediated complement activation was more prevalent in patients. Even in patients with genotypes that confer MBL sufficiency, 20.6% lacked MBL-mediated complement activation. In most patients with MBL-sufficient genotypes who lacked MBL-mediated activation at the acute phase of disease, lectin pathway functionality was restored at convalescence. In conclusion, genotypic MBL deficiency was not a risk factor for legionellosis. However, patients with legionellosis displayed deficient MBL-mediated complement activation even with MBL-sufficient genotypes. Together, these genotypical and functional data suggest that the observed deficiency of lectin pathway activation is an effect of legionellosis rather than a risk factor for acquiring it.