scholarly journals Energy Conservation and the Promotion ofLegionella pneumophilaGrowth: The Probable Role of Heat Exchangers in a Nosocomial Outbreak

2016 ◽  
Vol 37 (12) ◽  
pp. 1475-1480 ◽  
Author(s):  
Emilie Bédard ◽  
Simon Lévesque ◽  
Philippe Martin ◽  
Linda Pinsonneault ◽  
Kiran Paranjape ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Water Samples ◽  
Heat Exchangers ◽  
Gel Electrophoresis ◽  
Water System ◽  
Pulsed Field Gel Electrophoresis ◽  
Hot Water ◽  
Nosocomial Outbreak ◽  
Hospital Acquired

OBJECTIVETo determine the source of aLegionella pneumophilaserogroup 5 nosocomial outbreak and the role of the heat exchanger installed on the hot water system within the previous year.SETTINGA 400-bed tertiary care university hospital in Sherbrooke, Canada.METHODSHot water samples were collected and cultured forL. pneumophilafrom 25 taps (baths and sinks) within wing A and 9 taps in wing B. Biofilm (5) and 2 L water samples (3) were collected within the heat exchangers forL. pneumophilaculture and detection of protists. Sequence-based typing was performed on strain DNA extracts and pulsed-field gel electrophoresis patterns were analyzed.RESULTSFollowing 2 cases of hospital-acquired legionellosis, the hot water system investigation revealed a large proportion ofL. pneumophilaserogroup 5 positive taps (22/25 in wing A and 5/9 in wing B). High positivity was also detected in the heat exchanger of wing A in water samples (3/3) and swabs from the heat exchanger (4/5). The outbreak genotyping investigation identified the hot water system as the source of infections. Genotyping results revealed that all isolated environmental strains harbored the same related pulsed-field gel electrophoresis pattern and sequence-based type.CONCLUSIONSTwo cases of hospital-acquired legionellosis occurred in the year following the installation of a heat exchanger to preheat hospital hot water. No cases were reported previously, although the sameL. pneumophilastrain was isolated from the hot water system in 1995. The heat exchanger promotedL. pneumophilagrowth and may have contributed to confirmed clinical cases.Infect. Control Hosp. Epidemiol.2016;1475–1480

scholarly journals Detection of Carbapenemase Genes in Aquatic Environments in Rio de Janeiro, Brazil

2016 ◽  
Vol 60 (7) ◽  
pp. 4380-4383 ◽  
Author(s):  
Carlos Felipe Machado de Araujo ◽  
Dalton Marcondes Silva ◽  
Marcos Tavares Carneiro ◽  
Sthefanie Ribeiro ◽  
Marcela Fontana-Maurell ◽  
...  
Keyword(s):  
Water Samples ◽  
Gel Electrophoresis ◽  
Multilocus Sequence Typing ◽  
Rio De Janeiro ◽  
Pulsed Field Gel Electrophoresis ◽  
Aquatic Environments ◽  
Gene Pools ◽  
Content Type ◽  
Pulsed Field

ABSTRACTThis study reveals the presence of different carbapenemase genes (blaKPC,blaNDM,blaGES, andblaOXA48-likegenes) detected directly from water samples and clonal dispersion (by pulsed-field gel electrophoresis [PFGE] and multilocus sequence typing [MLST]) of KPC-2-producingEnterobacteriaceaein two important urban aquatic matrixes from Rio de Janeiro, Brazil, highlighting the role of aquatic environments as gene pools and the possibility of community spreading.

Sporadic Legionnaires' disease: the role of domestic electric hot-water tanks

2011 ◽  
Vol 140 (1) ◽  
pp. 172-181 ◽  
Author(s):  
S. F. DUFRESNE ◽  
M. C. LOCAS ◽  
A. DUCHESNE ◽  
C. RESTIERI ◽  
J. ISMAÏL ◽  
...  
Keyword(s):  
Potable Water ◽  
Water System ◽  
Water Systems ◽  
Pulsed Field Gel Electrophoresis ◽  
Hot Water ◽  
Clinical Isolates ◽  
Domestic Hot Water ◽  
Legionnaires Disease ◽  
Water Tanks

SUMMARYSporadic community-acquired legionellosis (SCAL) can be acquired through contaminated aerosols from residential potable water. Electricity-dependent hot-water tanks are widely used in the province of Quebec (Canada) and have been shown to be frequently contaminated withLegionellaspp. We prospectively investigated the homes of culture-proven SCAL patients from Quebec in order to establish the proportion of patients whose domestic potable hot-water system was contaminated with the sameLegionellaisolate that caused their pneumonia. Water samples were collected in each patient's home. Environmental and clinical isolates were compared using pulsed-field gel electrophoresis. Thirty-six patients were enrolled into the study.Legionellawas recovered in 12/36 (33%) homes. The residential and clinical isolates were found to be microbiologically related in 5/36 (14%) patients. Contaminated electricity-heated domestic hot-water systems contribute to the acquisition of SCAL. The proportion is similar to previous reports, but may be underestimated.

scholarly journals A Nosocomial Outbreak of Community-Associated Methicillin-ResistantStaphylococcus aureusamong Healthy Newborns and Postpartum Mothers

2007 ◽  
Vol 18 (2) ◽  
pp. 128-132 ◽  
Author(s):  
Andrea Saunders ◽  
Linda Panaro ◽  
Allison McGeer ◽  
Alana Rosenthal ◽  
Diane White ◽  
...  
Keyword(s):  
Gel Electrophoresis ◽  
Hospital Setting ◽  
Pulsed Field Gel Electrophoresis ◽  
Effective Control ◽  
Nosocomial Outbreak ◽  
Pulsed Field ◽  
Outbreak Period ◽  
Microbiological Testing ◽  
Unique Strain ◽  
Postpartum Mothers

BACKGROUND: Community-associated methicillin-resistantStaphylococcus aureus(CA-MRSA) has increasingly been isolated from individuals with no predisposing risk factors; however, such strains have rarely been linked to outbreaks in the hospital setting. The present study describes the investigation of an outbreak of CA-MRSA that occurred in the maternal-newborn unit of a large community teaching hospital in Toronto, Ontario.METHODS: Screening and clinical specimens collected from mothers and newborns delivered during the outbreak period, as well as from staff on the affected unit, were submitted for microbiological testing. Computerized delivery logs and nursing notes were reviewed, and a case control study was conducted.RESULTS: Analysis by pulsed-field gel electrophoresis revealed 38 babies and seven mothers with MRSA colonization and/or infection by the same unique strain (Canadian MRSA-10-related) from September to December 2004. Isolates were characterized as having the staphylococcal chromosome cassettemectype IVa and were positive for the Panton-Valentine leukocidin gene. No one health care worker was associated with all cases; however, mothers and newborns exposed to one particular nurse (Nurse A) were almost 23 times (odds ratio 22.7, 95% CI 3.3 to 195.9) more likely to acquire MRSA than those with no such contact. MRSA was successfully isolated from Nurse A and from an environmental swab of a telephone recently used by Nurse A; both isolates matched the pulsed-field gel electrophoresis pattern of the outbreak strain.CONCLUSION: The first nosocomial outbreak of CA-MRSA among healthy newborns and postpartum mothers in Canada is described. Effective control of sustained MRSA transmission within an institution may require prompt identification, treatment and monitoring of colonized and/or infected staff.

scholarly journals Sources of Listeria monocytogenes Contamination in a Cold-Smoked Rainbow Trout Processing Plant Detected by Pulsed-Field Gel Electrophoresis Typing

1999 ◽  
Vol 65 (1) ◽  
pp. 150-155 ◽  
Author(s):  
Tiina Autio ◽  
Sebastian Hielm ◽  
Maria Miettinen ◽  
Anna-Maija Sjöberg ◽  
Kaarina Aarnisalo ◽  
...  
Keyword(s):  
Rainbow Trout ◽  
Listeria Monocytogenes ◽  
Gel Electrophoresis ◽  
Pulsed Field Gel Electrophoresis ◽  
Hot Water ◽  
Processing Plant ◽  
Pulsed Field ◽  
Eradication Program ◽  
Fish Samples ◽  
Raw Fish

ABSTRACT Sites of Listeria monocytogenes contamination in a cold-smoked rainbow trout (Oncorhynchus mykiss) processing plant were detected by sampling the production line, environment, and fish at different production stages. Two lots were monitored. The frequency of raw fish samples containing L. monocytogenes was low. During processing, the frequency of fish contaminated with L. monocytogenes clearly rose after brining, and the most contaminated sites of the processing plant were the brining and postbrining areas. A total of 303 isolates from the raw fish, product, and the environment were characterized by pulsed-field gel electrophoresis (PFGE). PFGE yielded nine pulsotypes, which formed four clusters. The predominating L. monocytogenespulsotypes of the final product were associated with brining and slicing, whereas contaminants of raw fish were not detected in the final product. Air-mediated contamination in the plant could not be proved. In accordance with these results, an L. monocytogenes eradication program was planned. The use of hot steam, hot air, and hot water seemed to be useful in eliminatingL. monocytogenes. None of the control samples taken in the 5 months after the eradication program was implemented containedL. monocytogenes.

scholarly journals Simulation of the effectiveness of longitudinal rectangular fins on the efficiency of the double pipe heat exchanger

2019 ◽  
Vol 21 (4) ◽  
pp. 48-57
Author(s):  
N. F. Timerbaev ◽  
A. K. Ali ◽  
Omar Abdulhadi Mustafa Almohamed ◽  
A. R. Koryakin
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Cold Water ◽  
Tube Diameter ◽  
Hot Water ◽  
Outer Tube ◽  
Design Parameters ◽  
Double Pipe ◽  
Central Pipe ◽  
Pipe Heat

In this article, a mathematical simulation of a double pipe heat exchanger is carried out, having the longitudinal rectangular fins with the dimension of (2*3*1000) mm, mounted on the outer surface of the inner tube of the heat exchanger. In this paper, the advantage of using of that type of fins and its effect on the effectiveness of the heat exchanger are studied with the help of the computer program. The carried out research allowsmaking the calculation to find the optimum design parameters of heat exchangers. The outer tube diameter is (34.1mm) while the inner tube diameter is (16.05mm). The tubes wall thickness is (1.5mm) and the model length was (1 m). The hot water is flowing through the inner tube in parallel with the cold water that passing the outer tube. The hot and cold water temperature at the inlet is (75°C & 30°C) respectively. The mass flow rate inside the central pipe is (0.1 kg/s) while the annular pipe carrying (0.3 kg/s). In the present work, the program ANSYS Workbench 15.0 was used to find out the results of heat transfer as well as the behavior of liquids inside the heat exchangers.

scholarly journals Performance Analysis and Design Optimization of Shell and Tube Heat Exchangers

2021 ◽  
Author(s):  
praveen math
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Pressure Loss ◽  
Fluid Flows ◽  
Hot Water ◽  
Flow Conditions ◽  
Shell Side ◽  
Shell And Tube ◽  
Side Flow

Abstract Shell and Tube heat exchangers are having special importance in boilers, oil coolers, condensers, pre-heaters. They are also widely used in process applications as well as the refrigeration and air conditioning industry. The robustness and medium weighted shape of Shell and Tube heat exchangers make them well suited for high pressure operations. The aim of this study is to experiment, validate and to provide design suggestion to optimize the shell and tube heat exchanger (STHE). The heat exchanger is made of acrylic material with 2 baffles and 7 tubes made of stainless steel. Hot fluid flows inside the tube and cold fluid flows over the tube in the shell. 4 K-type thermocouples were used to read the hot and cold fluids inlet and outlet temperatures. Experiments were carried out for various combinations of hot and cold water flow rates with different hot water inlet temperatures. The flow conditions are limited to the lab size model of the experimental setup. A commercial CFD code was used to study the thermal and hydraulic flow field inside the shell and tubes. CFD methodology is developed to appropriately represent the flow physics and the procedure is validated with the experimental results. Turbulent flow in tube side is observed for all flow conditions, while the shell side has laminar flow except for extreme hot water temperatures. Hence transition k-kl-omega model was used to predict the flow better for transition cases. Realizable k- epsilon model with non-equilibrium wall function was used for turbulent cases. Temperature and velocity profiles are examined in detail and observed that the flow remains almost uniform to the tubes thus limiting heat transfer. Approximately 2/3 rd of the shell side flow does not surround the tubes due to biased flow contributing to reduced overall heat transfer and increased pressure loss. On the basis of these findings an attempt has been made to enhance the heat transfer by inducing turbulence in the shel l side flow. The two baffles were rotated in opposite direction to each other to achieve more circulation in the shell side flow and provide more contact with tube surface. Various positions of the baffles were simulated and studied using CFD analysis and th e results are summarized with respect to heat transfer and pressure loss.

scholarly journals Optimization of Pulsed-Field Gel Electrophoresis for Legionella pneumophila Subtyping

2010 ◽  
Vol 76 (5) ◽  
pp. 1334-1340 ◽  
Author(s):  
Haijian Zhou ◽  
Hongyu Ren ◽  
Bingqing Zhu ◽  
Biao Kan ◽  
Jianguo Xu ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Gel Electrophoresis ◽  
Water System ◽  
Epidemiological Data ◽  
Pulsed Field Gel Electrophoresis ◽  
Discriminatory Power ◽  
Similarity Coefficients ◽  
Pulsed Field ◽  
Software Analysis ◽  
High Degree

ABSTRACT A total of 32 strains of Legionella pneumophila were used to optimize pulsed-field gel electrophoresis (PFGE) for subtyping of L. pneumophila. Twenty-six isolates of L. pneumophila with various origins and 11 isolates from five different water systems were used as the panels. For optimization of electrophoretic parameters (EPs) of SfiI PFGE, 26 isolates were analyzed with SfiI digestion, using four EPs yielding the same D value. The EP of a switch time of 5 to 50 s for 21 h had the smallest similarity coefficients and was declared the optimal EP for SfiI PFGE of L. pneumophila. By software analysis and pilot study, AscI was chosen as another PFGE enzyme. AscI PFGE could cluster the isolates from each water system into the same or very similar patterns and had a high degree of typing concordance with other molecular methods. In evaluating the discriminatory power of AscI with the panel of 26 isolates, AscI PFGE gave one single pattern and a D value of 100%. AscI PFGE had a high discriminatory power and a high degree of consistency with epidemiological data and other molecular typing methods for L. pneumophila subtyping, and hence, AscI could be used as a restriction enzyme in PFGE subtyping of L. pneumophila.

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