Università degli studi di Modena e Reggio Emilia

Legionella colonization in hospital hot water distribution networks was evaluated following 36 months of continuous treatment with monochloramine and compared with chlorine dioxide. Nitrite, nitrate, chlorite, chlorate, bromide, trihalomethanes and haloacetic acids as well as the biocide concentration at sampled points were measured. Only 8/84 samples treated with monochloramine were found contaminated and after the first 8 months of treatment no Legionella was isolated. Chlorine dioxide was associated with a strong reduction in Legionella contamination compared to pretreatment, but differences according to the device were observed. Monochloramine between 2 and 3 mg l−1 and chlorine dioxide between 0.50 and 0.70 mg l−1 were needed to control Legionella colonization. Comparing no- and post-flush samples, a higher frequency of no-flush positive samples was noted using chlorine dioxide, suggesting an increased risk for patients when they open the tap. No increase in chlorite levels and no water nitrification occurred by using monochloramine. Chlorite at levels exceeding the limit requested for drinking water was measured when chlorine dioxide was applied. In conclusion, we highlight that continuous injection of monochloramine should be considered as an effective alternative to chlorine dioxide in controlling legionellae contamination inside hospital water distribution systems

We investigated two consecutive Serratia marcescens (S. marcescens) outbreaks which occurred in a neonatal intensive care unit (NICU) of a tertiary level hospital in North Italy in a period of 10 years (January 2003-December 2012). Risk factors associated with S. marcescens acquisition were evaluated by a retrospective case-control study. A total of 21,011 clinical samples was examined: S. marcescens occurred in 127 neonates: 43 developed infection and 3 died. Seven clusters were recorded due to 12 unrelated clones which persisted for years in the ward, although no environmental source was found. The main epidemic clone A sustaining the first cluster in 2003 reappeared in 2010 as an extended spectrum ?-lactamase (ESBL)-producing strain and supporting the second epidemic. Birth weight, gestational age, use of invasive devices and length of stay in the ward were significantly related to S. marcescens acquisition. The opening of a new ward for non-intensive care-requiring neonates, strict adherence to alcoholic hand disinfection, the timely identification and isolation of infected and colonized neonates assisted in containing the epidemics. Genotyping was effective in tracing the evolution and dynamics of the clones demonstrating their long-term persistence in the ward.

Introduction. Interferon Gamma Release Assays (IGRAs) are being largely used worldwide for the screening of tuberculosis infection among subjects likely to undergo multiple testing, such as health care workers (HCW). In theory, IGRAs should overcome the risk of false positive results due to the boosting effect, at difference with the in vivo tuberculin skin test. Evaluation of IGRA results in HCW in a non-experimental setting over several years may provide information on the real-life performance of these tests in daily practice. We reviewed the results of QuantiFERON-TB In-Tube (QTF-IT) tests performed on HCW over nearly five years, with particular focus on repeated tests. Methods: We extracted the anonymised electronic records of all consecutive QFT-IT performed on HCW between May 2006 and December 2010. All tests were done at the Laboratory of Microbiology and Virology of University Hospital of Modena (Italy). Results: A total of 1,531 tests were performed in 1,189 individuals (mean age ± SD: 37±10 years; 29% male). In 226 subjects (37±9 years; 31% male) QFT-IT was repeated at least once. Among subjects who underwent single testing (n=963, 81%), 85% were negative and 14% positive, as compared to the results at first test among subjects with repeated tests (69% negative, 27% positive; p<0.0001). In the majority of cases (84%) a second QFT-IT provided a concordant valid result. Reversion (from positive to negative) occurred more frequently than conversion (from negative to positive) (respectively, 10% vs. 4% of repeated tests). Rate of indeterminate results was extremely low, 0.4% in subjects with single testing and 1.8% at first test in subjects with multiple tests. At second testing, indeterminate QFT-IT results at first testing became negative in all but one case, which remained indeterminate. Conclusions: In this non-experimental routine setting of tuberculosis infection screening in HCW, subjects who underwent repeated tests were more likely to have a positive QFT-IT at first testing, as compared to subjects with single testing. However, a repeated QFT-IT confirmed previous results in almost all cases. Reversions occurred more often than conversions. Rate of indeterminate QFT-IT results was extremely low, thus indicating a very good technical performance of this test in HCW in a low TB prevalence area.