Prevalence of anti-legionella antibodies among Italian hospital workers

This study evaluated the prevalence of anti-legionella antibodies in workers at hospitals with a long-term history of legionella contamination. The hospitals are located in Milan and Turin, northern Italy, and in Naples and Bari, southern Italy. Antibody prevalence and titres of healthcare workers, medical and dental students and blood donors were assessed. In total 28.5% of subjects were antibody positive, most frequently to L. pneumophila serogroups 7-14. Major differences were observed in seroprevalence and type of legionella antibody in persons from different geographic areas. Healthcare workers had a significantly higher frequency of antibodies compared with blood donors in Milan (35.4 vs 15.9%, P<0.001), whereas in Naples both groups exhibited high antibody frequency (48.8 vs 44.0%) and had a higher proportion of antibodies to legionella serogroups 1-6. Dental workers had a higher seroprevalence than office staff in Bari, but not in Turin, where daily disinfecting procedures had been adopted to avoid contamination of dental unit water. No association was found between the presence of antibodies and the presence of risk factors for legionellosis, nor with the occurrence of pneumonia and/or flu-like symptoms. In conclusion, the presence of legionella antibodies may be associated with occupational exposure in the hospital environment, but there was no evidence of any association with disease.

Clinical and environmental distribution of Legionella pneumophila in a university hospital in Italy: efficacy of ultraviolet disinfection

The molecular epidemiology of Legionella pneumophila in the 'V. Monaldi' University Hospital was studied. Seven cases of nosocomial Legionnaires' disease were diagnosed between 1999 and 2003. Two clinical legionella strains obtained from two patients in the adult cardiac surgery unit (CSU) and 30 environmental legionella strains from the paediatric and adult CSUs, neonatal intensive care unit (NICU) and the cardiorespiratory intensive care unit (CR-ICU) were serotyped and genotyped. L. pneumophila serogroup 1/Philadelphia with an identical pulsed-field gel electrophoresis (PFGE) profile A was isolated from two patients in the adult CSU, and from three and one water samples taken in the adult CSU and the paediatric CSU, respectively, from 2001 to 2002. Furthermore, L. pneumophila serogroup 3 with an identical PFGE profile B was identified in 20 environmental strains from all wards, L. pneumophila serogroup 3 with PFGE profile C was identified in a single environmental strain from the CR-ICU, and non-pneumophila Legionella with identical PFGE profile D was identified in five environmental strains from the adult CSU, paediatric CSU and NICU. Ultraviolet irradiation was effective in disinfection of the hospital water supplies in the adult and paediatric CSUs contaminated by L. pneumophila clone associated with nosocomial Legionnaires' disease. In conclusion, these data demonstrate that two cases of nosocomial legionellosis were caused by the persistence of a single clone of L. pneumophila serogroup 1/Philadelphia in the hospital environment, and that disinfection by ultraviolet irradiation may represent an effective measure to prevent nosocomial Legionnaires' disease.

[The discharge form: advantages and limits legionellosis cases individuation]

Despite legionellosis surveillance is active in Italy since many years, the disease notification appears still undervalued. A multicentric survey was carried out among 5 big Italian hospitals. It examined 11,435 discharge forms (1999-2001), reporting pneumonia diagnosis. Legionellosis (II class of notify system for infectious disease) was studied among pneumonia diagnosis by discharge forms. According to the ICD9-CM, there's no specific code for legionellosis (this disease is included among "others gram-negative pneumonia"). So the presumed pneumonia imputable to Legionella spp were the 2.7% of the whole number of analyzed discharge forms. Besides, the data regarding the other pneumonia showed that the etiological agent was specified only in the 11.2% of the case. This situation could be rectified both introducing adequate discharge forms codes and promoting the etiological diagnosis during the hospital stay.

[Environmental diffusion of Legionella spp and legionellosis frequency among patients with pneumonia: preliminary results of a multicentric Italian survey]

A multicentric Italian investigation on legionnaires' disease is in course to clarify host factors as well as pathogen associated characteristics involved in the infection/disease. The main goal of the research plan is to account for some critical aspects concerning identification and prevention of legionellosis. To improve knowledge on factors associated with Legionella spp colonisation in hot waters, to detect cases and to characterize risk factors in subjects which develop pneumonia are specific objectives of the research programme. Preliminary results show that hot waters of houses and hotels are frequently contaminated (22.6% and 54.6%, respectively), mainly by L. pneumophila. Microbial concentrations were low in domestic waters (<1.000 ufc/l), but higher in samples from the hotels (geom. mean 1.85 x 10(3) ufc/l). Warming system, age of the plant, type of building were risk factors significantly associated with Legionella spp positivity. The active surveillance on patients affected by pneumonia with search for Legionella urinary antigen allowed the identification of 34 cases, 3 of which of nosocomial origin, corresponding to 4.2% of the screened pneumonia. After informed consent, 26 subjects were recruited for a case-control-study to clarify risk factors for the disease.