Search

Objectives: We assessed the contamination with Legionella pneumophila (Lp) of the hot water network (HWN) of a hospital, mapped the risk of contamination, and evaluated the relatedness of isolates. We further validated phenotypically the biological features that could account for the contamination of the network., Methods: We collected 360 water samples from October 2017 to September 2018 in 36 sampling points of a HWN of a building from a hospital in France. Lp were quantified and identified with culture-based methods and serotyping. Lp concentrations were correlated with water temperature, date and location of isolation. Lp isolates were genotyped by pulsed-field gel electrophoresis and compared to a collection of isolates retrieved in the same HWN two years later, or in other HWN from the same hospital., Results: 207/360 (57.5%) samples were positive with Lp. In the hot water production system, Lp concentration was negatively associated with water temperature. In the distribution system, the risk of recovering Lp decreased when temperature was >55 °C (p < 10 -3 ), the proportion of samples with Lp increased with distance from the production network (p < 10 -3 ), and the risk of finding high loads of Lp increased 7.96 times in summer (p = 0.001). All Lp isolates (n = 135) were of serotype 3, and 134 (99.3%) shared the same pulsotype which is found two years later (Lp G). In vitro competition experiments showed that a 3-day culture of Lp G on agar inhibited the growth of a different pulsotype of Lp (Lp O) contaminating another HWN of the same hospital (p = 0.050). We also found that only Lp G survived to a 24h-incubation in water at 55 °C (p = 0.014)., Conclusion: We report here a persistent contamination with Lp of a hospital HWN. Lp concentrations were correlated with water temperature, season, and distance from the production system. Such persistent contamination could be due to biotic parameters such as intra-Legionella inhibition and tolerance to high temperature, but also to the non-optimal configuration of the HWN that prevented the maintenance of high temperature and optimal water circulation., Competing Interests: Declaration of competing interest None of the authors have anything to disclose., (Copyright © 2023 Elsevier GmbH. All rights reserved.)

Resistance Nodulation cell Division (RND) efflux pumps are known to contribute to the tolerance of Pseudomonas putida to aromatic hydrocarbons, but their role in antibiotic resistance has not been fully elucidated. In this study, two types of single-step multidrug-resistant (MDR) mutants were selected in vitro from reference strain KT2440. Mutants of the first type were more resistant to fluoroquinolones and β-lactams except imipenem, and overproduced the efflux system TtgABC as a result of mutations occurring in regulator TtgR. In addition to TtgABC, mutants of the second type such as HPG-5 were found to upregulate a novel RND pump, dubbed ParXY/TtgC, which accommodates cefepim, fluoroquinolones and aminoglycosides. As demonstrated by gene deletion experiments, TtgABC and ParXY/TtgC are both under the positive control of a two-component system, PpeRS. Whole-genome sequence analyses revealed that mutant HPG-5 harbours a mutation inactivating the gene (sucD) of succinyl-CoA synthetase, an enzyme of the tricarboxylic cycle. Disruption of sucD in strain KT2440 reproduced the resistance phenotype of HPG-5, and activated the glyoxylate shunt. Finally, identification of two MDR clinical strains of P. putida that jointly overexpress TtgABC and ParXY/TtgC, of which one is a sucD mutant, highlights the role of these efflux systems as determinants of antibiotic resistance., (© 2020 Society for Applied Microbiology and John Wiley & Sons Ltd.)

Aim: We aimed to evaluate the accuracy of the dosage of calprotectin in ascitic fluid (AF) using the Quantum Blue assay, for the prompt diagnosis of spontaneous bacterial peritonitis (SBP)., Methods: We prospectively collected 236 AF samples from 119 cirrhotic patients hospitalized in two French centers between May 2016 and May 2017. Bloody and chylous/cloudy AF, and secondary peritonitis were excluded. SBP was diagnosed if neutrophils in AF were >250/mm 3 using standard cytology. The Quantum Blue Reader selectively measured the calprotectin antigen (MRP8/14) in 12 min within the measurable range from 0.18 to 1.80 μg/mL; values outside this range were registered as 0.17 and 1.81 μg/mL., Results: A total of 36 AF were considered as SBP (15.2%). SBP had higher median levels of calprotectin than non-SBP (1.81 vs. 0.25 μg/mL, P < 0.001). Calprotectin levels were positively correlated with neutrophils in AF (r = 0.57, P < 0.001) and C-reactive protein (r = 0.43, P < 0.001), but not with the Child-Pugh and Model for End-Stage Liver Disease scores. The optimal threshold of calprotectin to diagnose SBP was set at 1.51 μg/mL (80th percentile of calprotectin), yielding sensitivity, specificity, and positive and negative predictive values of 86.1%, 92.0%, 65.9%, and 97.3%, respectively. Only one asymptomatic patient with SBP had a low calprotectin level, but a high serum C-reactive protein level that strongly suggested an ongoing infection. We also showed that intraclass correlation coefficients for inter- and intra-observer agreement were excellent, with 0.95 and 0.89, respectively., Conclusions: The dosage of calprotectin in AF using the Quantum Blue assay is a rapid and reliable method of ruling out SBP in hospitalized cirrhotic patients., (© 2018 The Japan Society of Hepatology.)