Maria Luisa Ricci

Pneumonia associated with a dental unit waterline

Department of Infectious Parasitic and ImmuneMediated Diseases, Istituto Superiore di Sanita, Rome, Italy (M L Ricci BiolD, S Fontana PhD, F Pinci BiolD, M Scaturro PhD); Azienda Unita Sanitaria Locale, Forli, Italy (E Fiumana MD); Azienda Unita Sanitaria Locale, Cesena, Italy (M F Pedna BiolD); Agenzia Regionale Prevenzione e Ambiente, Bologna, Italy (M A Bucci Sabattini BiolD); and “G B Morgagni-Pierantoni” Hospital, Department of Emergency Anaesthesia and Intensive Care Unit, Forli, Italy (P Farolfi MD)

Persistence of the Same Strain of Legionella pneumophila in the Water System of an Italian Hospital for 15 Years

In 2004, an outbreak of legionnaires disease occurred in a hospital in northern Italy with a water system that had been disinfected multiple times since 1990 and equipped with a continuous disinfecting system. Molecular typing linked the outbreak to contamination of the hospital water system and demonstrated the persistence of a predominant strain of Legionella pneumophila for 15 years.

Determination of Legionella pneumophila susceptibility to Melaleuca alternifolia Cheel (tea tree) oil by an improved broth micro-dilution method under vapour controlled conditions

The aim of this study was to determine the in vitro activity of Melaleuca alternifolia Cheel (tea tree) oil (TTO) against 22 strains of Legionella pneumophila of different serogroup and source of isolation. Both a standard broth micro-dilution method, with slight modifications, and a micro-atmosphere diffusion method were used. Furthermore, we have established a simple sealing procedure in the micro-dilution method to determine the antibacterial activity of TTO against Legionella in aqueous phase. The results showed that L. pneumophila, quite irrespective of serogroup and source of isolation, is exquisitely sensitive to TTO, with minimal inhibitory concentration (MIC) ranging from 0.125 to 0.5% v/v, and a bactericidal activity at 0.5% v/v. In addition, we show here that TTO vapours exert critical activity, that must be controlled for reproducible MIC determinations. Overall, our data suggest that TTO could be active as anti-Legionella disinfectant, for control of water system contamination, especially in spas, in small waterlines or in particular respiratory medical devices.

Diphtheria Antibody Levels in the Italian Population

Abstract Immunity to diphtheria was assessed in serum samples obtained from 3111 healthy Italian males and females aged 0–84 years. Diphtheria antitoxin was tested using a double-antigen, time-resolved fluorescence immunoassay (DA-DELFIA). According to internationally accepted criteria, antitoxin concentrations <0.01 IU/ml indicate susceptibility to diphtheria, those ≥0.01–0.09 IU/ml provide basic or inadequate protection, and concentrations ≥0.1 IU/ml are protective. By these criteria, 9.9% (95% CI, 8.9 to 11.18) of the participants were susceptible to diphtheria, 30.2% (95% CI, 28.6 to 31.9) had basic protection, and 59.9% (95% CI, 58.1 to 61.6) were protected. The prevalence of unprotected individuals showed an age-related increase, up to the 45–49-year-old age group for females and the 50–54-year-old age group for males (34.9% and 31.3% of individuals, respectively). The prevalence of immunity did not significantly differ in relation to sex in any of the age groups. These results indicate that booster shots should be routinely provided to the adult population in order to maintain a protective level of diphtheria antibodies.

Lack of activity of transferring towards Streptococcus spp.

Clinically relevant Streptococcus spp. were tested for their susceptibility towards human serum transferrin (TR) and lactoferrin (LF). Neither clinical isolates or type strains were inhibited by transferrins (5 mg/ml). All species tested were shown to be able to grow under iron-limiting conditions (<0.1 μM) and this might account for the lack of TR or LF activity towards streptococci. Even if not sensitive to LF and TR, some species were shown to bind LF in the apo-form.

Protective activity of a murine monoclonal antibody against acute and chronic experimental infection with type IV group B streptococcus

A murine IgM monoclonal antibody (MAb H11) was developed against the type polysaccharide capsular antigen of group B streptococcus (GBS), serotype IV, after intraperitoneal immunisation of BALB/c mice with heat-killed bacteria. MAb H11 reacted in immunodiffusion with the purified polysaccharide in both its sialylated and desialylated form, giving a line of identity, and opsonised type IV GBS strains in an in vitro assay. When administered at the time of intraperitoneal lethal challenge with homologous GBS, or 4 h earlier, MAb H11 protected 90% of the mice. Protection was still observed when MAb H11 was given 4 h after the challenge. This MAb was strongly effective in preventing septic arthritis induced by type IV GBS.

A multicenter study of viable PCR using propidium monoazide to detect Legionella in water samples

Legionella quantification in environmental samples is overestimated by qPCR. Combination with a viable dye, such as Propidium monoazide (PMA), could make qPCR (named then vPCR) very reliable. In this multicentre study 717 artificial water samples, spiked with fixed concentrations of Legionella and interfering bacterial flora, were analysed by qPCR, vPCR and culture and data were compared by statistical analysis. A heat-treatment at 55 °C for 10 minutes was also performed to obtain viable and not-viable bacteria. When data of vPCR were compared with those of culture and qPCR, statistical analysis showed significant differences (P < 0.001). However, although the heat-treatment caused an abatement of CFU/mL ≤1 to 1 log10 unit, the comparison between untreated and heat-treated samples analysed by vPCR highlighted non-significant differences (P > 0.05). Overall this study provided a good experimental reproducibility of vPCR but also highlighted limits of PMA in the discriminating capability of dead and live bacteria, making vPCR not completely reliable.

Legionella pneumophila serogroup 5 infection in the presence of multiple environmental contamination. The importance of a bacteriological diagnosis

Legionella pneumophila is a pathogen that causes severe pneumonia in humans; L. pneumophila serogroup 1 accounts for at least 90% of infections. This is not linked to an environmental predominance of Legionella pneumophila 1, but may be due to a greater virulence of the strain. L. pneumophila sg 5 has also been reported, albeit less frequently, to be a cause of the disease. We report a case of L. pneumophila sg 5 occurring in a large hospital in southern Italy (Apulia region), where both L. pneumophila sg 1 and sg 5 were detected in the water supply; the nosocomial origin was demonstrated by molecular subtyping (PFGE). An environmental investigation, performed immediately after diagnosis of the case of legionellosis, identified a ow L. pneumophila sg 5 contamination level. Our experience highlights that in hospital, risk assessment, in rder to institute control measures for Legionella, should be carried out not only in response to a case of the disease and/or in risk wards only, as described in the Italian Guidelines, but periodically in every ward. The present study confirms that, although in the community L. pneumophila sg 1 is the most frequent strain isolated in both outbreaks and isolated cases, in hospital other serogroups and species may often cause infection because of the high susceptibility of the hosts.

Legionnaires' Disease Pseudoepidemic Due to Falsely Positive Urine Antigen Test Results

Maria Cristina Rota, Stefano Fontana, Carmen Montaño-Remacha, Maria Scaturro, Maria Grazia Caporali, Vincenzo Vullo, Laura Scorzolini, Andreina Ercole, Maria Luisa Ricci National Centre for Epidemiology, Surveillance and Health Promotion, National Institute of Health, Rome, Italy; Infectious, Parasitic and Immune-Mediated Diseases Department, National Institute of Health, Rome, Italy; Public Health and Infectious Diseases Department, Sapienza University of Rome, Rome, Italy; Public Health Prevention Department, Local Health Unit Rome A, Rome, Italy

Characterization of a spontaneous avirulent mutant of Legionella pneumophila Serogroup 6: Evidence of DotA and flagellin involvement in the loss of virulence

The pathogenesis of Legionella pneumophila mainly resides in its ability to inhibit the phagosome-lysosome fusion, which normally prevents the killing of the host cells. In order to characterize the molecular alterations that occurred in a spontaneous avirulent mutant of Legionella pneumophila serogroup 6, named Vir-, we investigated the ability of the mutant to adhere to and multiply in the WI26VA4 alveolar epithelial cell line and in human macrophages, when compared to its parental strain, Vir+. We also determined the colocalization of bacteria with LAMP-1 to gain an insight into the phagosome-lysosome fusion process. Additionally, we determined the flagellin expression and dotA nucleotide sequencing. We observed a lack of expression of flagellin and an in-frame mutation in the dotA. gene. The data obtained strongly suggest the loss of virulence of the mutant could probably be due to the absence of flagellin and the dysfunctional type IV secretion System, resulting from the DotA protein being severely compromised.