Serratia marcescens in a neonatal intensive care unit: two long-term multiclone outbreaks in a 10-year observational study

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

Hospital-acquired Legionella infections: an update on the procedures for controlling environmental contamination

The waterborne healthcare-associated infections are mainly sustained by Legionella and Pseudomonas spp. Various water factors and plumbing characteristics, and the interaction with other water microorganisms are considered to be predictive of Legionella contamination. It is therefore mandatory to organize plans of surveillance, prevention and control in order to avoid disease appearance in immunosuppressed patients, with higher risk of death. Guidelines for the prevention of Legionnaires' disease have been published, benefiting those who face this problem, but definitive standardized solutions do not exist yet. Here we describe fifteen years of activity, during which our study group gathered interesting data on the control of Legionella contamination. Water disinfection is not generally sufficient to control the risk of infection, but a complex water safety plan should be developed, including system maintenance, training of staff and implementation of a clinical surveillance system aimed at early detection of cases. Concerning the control measures, we evaluated the effectiveness of different treatments suggested to reduce Legionella spp contamination, comparing our results with the current literature data. The performance ranking was highest for the filter, followed by boilers at high temperature, monochloramine and, at a lower level, chlorine dioxide; the effectiveness of hyperchlorination was limited, and thermal shock was even more ineffective

Monochloramine and chlorine dioxide for controlling Legionella pneumophila contamination: biocide levels and disinfection by-products (DBPs) formation in hospital water networks.

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 system

A Culture-Proven Case of Community-Acquired Legionella Pneumonia Apparently Classified as Nosocomial: Diagnostic and Public Health Implications

We report a case of Legionella pneumonia in a 78-year-old patient affected by cerebellar haemangioblastoma continuously hospitalised for 24 days prior to the onset of overt symptoms. According to the established case definition, this woman should have been definitely classified as a nosocomial case (patient spending all of the ten days in hospital before onset of symptoms). Water samples from the oncology ward were negative, notably the patient’s room and the oxygen bubbler, and the revision of the case history induced us to verify possible contamination in water samples collected at home. We found that the clinical strain had identical rep-PCR fingerprint of L. pneumophila serogroup 1 isolated at home. The description of this culture-proven case of Legionnaires’ disease has major clinical, legal, and public health consequences as the complexity of hospitalised patients poses limitations to the rule-of-thumb surveillance definition of nosocomial pneumonia based on 2–10-day incubation period

Quantiferon-TB Gold In-Tube Tests In Hospital Health Care Workers: A Five Years Experience

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

Routine hospital use of a new commercial whole blood interferon-gamma assay for the diagnosis of tuberculosis infection

Rationale: Interferon (IFN)-? blood tests may improve the current level of diagnostic accuracy for tuberculosis infection. The QuantiFERON-TB Gold (QFT-Gold) has been used in selected populations and shows higher specificity than the tuberculin skin test (TST). Objective: To evaluate the QFT-Gold test in unselected patients and assess the level of agreement with the TST. Methods: The test has been routinely performed on whole blood samples in our microbiology laboratory for 8 months. Demographic, clinical, and microbiological data have been collected and correlated to the QFT-Gold results. Measurements and Main Results: Of 318 patients tested, 68 (21.4%) gave an indeterminate (low positive mitogen control) QFT-Gold result. Indeterminate results were significantly overrepresented in patients with a negative TST (28.9% vs. 6.6% in TST-positive patients; p &lt; 0.0001, ?2 test) and were more frequent in patients receiving immunosuppressive therapies than in those who were not receiving such treatments (odds ratio, 3.35; 95% confidence interval, 1.84–6.08; p &lt; 0.0001). After excluding indeterminate results, the concordance between QFT-Gold and TST was significantly lower in Bacille Calmette-Guérin–vaccinated individuals (41.5%) than in nonvaccinated individuals (80.3%) (p &lt; 0.0001). In 11 patients with active tuberculosis (5 culture-confirmed), QFT-Gold provided more positive results than the TST (66.7% vs. 33.3%; p = 0.165). Conclusions: The QFT-Gold test is feasible in routine hospital use for the diagnosis of tuberculosis infection. As with the TST, immunosuppression may negatively affect the test's performance, with a significant rate of indeterminate results in the most vulnerable population