BACKGROUND: Dental Unit Water Line (DUWL) deliver water to different handpieces in a dental unit. The water in DUWL circulates in a closed system, where it is taken from a container. The quality of dental water is of considerable importance since patients and dental staff are regularly exposed to water and aerosols generated from dental equipment. Output water from DUWLs may be a potential source of infection for both dental health care personnel and patients.
OBJECTIVE: To assess the microbial contamination in the DUWL among dental clinics in Chennai.
METHODS: An in vitro study was conducted on 60 water samples from 20 dental clinics in Chennai in December 2019. Water samples were collected from three different sources of the Dental unit according to ADA guidelines. The collected samples were assessed for the presence of Aspergillus, Acinetobacter, Pseudomonas aeruginosa, and Legionella by agar plate method. The data were analysed using SPSS software version 20.
RESULTS: Legionella was the most prevalent microorganism with 70% prevalence in a three-way syringe and 50% in scaler and airotor, followed by Pseudomonas aeruginosa and Acinetobacter with 10% prevalence in scaler and airotor and Aspergillus with a prevalence of 10% in the three-way syringe.
CONCLUSIONS: Most of the dental units were contaminated with Aspergillus, Legionella, Pseudomonas aeruginosa and Acinetobacter which pose a serious threat to the patients as well as the dentists.

BACKGROUND: Cooling towers containing Legionella spp are a high-risk source of Legionnaires\' disease outbreaks. Manually locating cooling towers from aerial imagery during outbreak investigations requires expertise, is labour intensive, and can be prone to errors. We aimed to train a deep learning computer vision model to automatically detect cooling towers that are aerially visible.
METHODS: Between Jan 1 and 31, 2021, we extracted satellite view images of Philadelphia (PN, USA) and New York state (NY, USA) from Google Maps and annotated cooling towers to create training datasets. We augmented training data with synthetic data and model-assisted labelling of additional cities. Using 2051 images containing 7292 cooling towers, we trained a two-stage model using YOLOv5, a model that detects objects in images, and EfficientNet-b5, a model that classifies images. We assessed the primary outcomes of sensitivity and positive predictive value (PPV) of the model against manual labelling on test datasets of 548 images, including from two cities not seen in training (Boston [MA, USA] and Athens [GA, USA]). We compared the search speed of the model with that of manual searching by four epidemiologists.
RESULTS: The model identified visible cooling towers with 95·1% sensitivity (95% CI 94·0-96·1) and a PPV of 90·1% (95% CI 90·0-90·2) in New York City and Philadelphia. In Boston, sensitivity was 91·6% (89·2-93·7) and PPV was 80·8% (80·5-81·2). In Athens, sensitivity was 86·9% (75·8-94·2) and PPV was 85·5% (84·2-86·7). For an area of New York City encompassing 45 blocks (0·26 square miles), the model searched more than 600 times faster (7·6 s; 351 potential cooling towers identified) than did human investigators (mean 83·75 min [SD 29·5]; mean 310·8 cooling towers [42·2]).
CONCLUSIONS: The model could be used to accelerate investigation and source control during outbreaks of Legionnaires\' disease through the identification of cooling towers from aerial imagery, potentially preventing additional disease spread. The model has already been used by public health teams for outbreak investigations and to initialise cooling tower registries, which are considered best practice for preventing and responding to outbreaks of Legionnaires\' disease.
BACKGROUND: None.

BACKGROUND: Legionnaires\' disease is a type of severe pneumonia caused by Legionella bacteria. The case fatality rate in this disease is 5-10%. People with various comorbidities, smokers and the elderly are at greater risk of developing the disease.
OBJECTIVE: The aim of the work is to present the results of an epidemiological investigation into the outbreak of Legionnaires\' disease that occurred in the city of Rzeszów and the surrounding area in August and September 2023 and to present the threat related to the presence of Legionella bacteria in water supply installations and networks.
METHODS: The material for this publication was data from an epidemiological investigation conducted in the outbreak of Legionnaires disease in Rzeszów in 2023.
RESULTS: Epidemiological investigation revealed 165 cases of Legionnaires\' disease in the outbreak, including 152 confirmed cases and 13 probable cases. The case fatality rate in a legionellosis outbreak was 15%. Environmental tests were carried out in residential and public buildings and industrial installations during the investigation. As part of environmental tests, 187 water samples were collected, including 87 warm water samples.
CONCLUSIONS: The outbreak of Legionnaires\' disease in the city of Rzeszów draws attention to the potential threat from the Legionella bacteria to the health and life of especially elderly people suffering from chronic diseases. The environmental tests carried out confirmed the highest number of Legionella bacteria at medium and high levels in water samples taken in the private apartments of sick people. Despite the lack of strict legal regulations clearly specifying the obligations regarding periodic disinfection of internal hot water supply installations, cooperation with their owners should be undertaken to enforce plans and actions in this area.
UNASSIGNED: Choroba legionistów jest typem ciężkiego zapalenia płuc wywołanego przez bakterie Legionella. Śmiertelność w tej chorobie wynosi 5-10%. Na większe ryzyko zachorowania narażone są osoby z różnymi chorobami współistniejącymi, osoby palące i osoby w starszym wieku.
UNASSIGNED: Celem pracy jest przedstawienie wyników dochodzenia epidemiologicznego w ognisku choroby legionistów które wystąpiło na terenie miasta Rzeszowa i okolic w sierpniu i wrześniu 2023 roku oraz przedstawienie zagrożenia związanego z obecnością bakterii Legionella w instalacjach i sieciach wodociągowych.
UNASSIGNED: Materiałem do niniejszej publikacji były dane z dochodzenia epidemiologicznego prowadzonego w ognisku choroby legionistów w Rzeszowie w 2023 roku.
UNASSIGNED: Dochodzenie epidemiologiczne ujawniło 165 przypadków choroby legionistów w ognisku, w tym 152 przypadki potwierdzone oraz 13 przypadków prawdopodobnych. Śmiertelność w ognisku legionelozy wynosiła 15%. W toku prowadzonego dochodzenia prowadzono badania środowiskowe w budynkach mieszkalnych i użyteczności publicznej oraz instalacjach przemysłowych. W ramach badań środowiskowych pobrano 187 próbek wody, w tym 87 próbek wody ciepłej.
UNASSIGNED: Ognisko choroby legionistów na terenie miasta Rzeszowa zwraca uwagę na potencjalne zagrożenie z strony bakterii Legionella dla zdrowia i życia szczególnie osób starszych cierpiących na choroby przewlekłe. Przeprowadzone badania środowiskowe potwierdziły najwyższą liczbę bakterii Legionella na poziomie średnim i wysokim w próbkach wody pobranych w mieszkaniach prywatnych osób chorych. Pomimo braku ścisłych uregulowań prawnych wskazujących wprost na obowiązki dotyczące okresowej dezynfekcji wewnętrznych instalacji zaopatrzenia w wodę ciepłą, należy podjąć współpracę z ich właścicielami w celu wyegzekwowania planów i działań w tym zakresie.

The majority of antibiotics are natural products, with microorganism-generated molecules and their derivatives being the most prevalent source of drugs to treat infections. Thus, identifying natural products remains the most valuable resource for novel therapeutics. Here, we report the discovery of a series of dormant bacteria in honey that have bactericidal activity toward Legionella, a bacterial pathogen that causes respiratory disease in humans. We show that, in response to bacterial products secreted by Legionella, the honey bacteria release diffusible antimicrobial molecules. Remarkably, the honey bacteria only produce these molecules in response to Legionella spp., when compared to a panel of 24 bacterial pathogens from different genera. However, the molecules induced by Legionella have broad activity against several clinically important pathogens, including many high-priority pathogens. Thus, Legionella spp. are potent drivers of antimicrobial molecule production by uncharacterized bacteria isolated from honey, providing access to new antimicrobial products and an unprecedented strategy for discovering novel antibiotics.
OBJECTIVE: Natural products generated by microorganisms remain the most viable and abundant source of new antibiotics. However, their discovery depends on the ability to isolate and culture the producing organisms and to identify conditions that promote antibiotic production. Here, we identify a series of previously undescribed bacteria isolated from raw honey and specific culture conditions that induce the production of antimicrobial molecules that are active against a wide variety of pathogenic bacteria.

Legionnaires\' disease is a potentially severe type of pneumonia most often caused by the organism Legionella pneumophila. Exposure to this bacterial pathogen typically happens in the community but may also occur in the hospital setting. This report describes the case of a patient who presented due to 10 days of fever, shortness of breath, and diarrhea, with initial imaging demonstrating multifocal pneumonia. The patient was appropriately started on empiric antibiotics for community-acquired pneumonia and admitted to the medicine floor. The patient showed no meaningful improvement in his initial hospital course on empiric antibiotics with continued oxygen requirements. Meanwhile, urine Legionella antigen testing returned positive on hospital day four, and after tailoring antibiotics accordingly, the patient\'s clinical status improved significantly. This case report highlights the efficacy of broad testing in the initial admission and the need for constant re-evaluation in the context of a patient not improving with appropriate therapy.

Legionella, one of the main pathogens that causes community-acquired pneumonia, can lead to Legionella pneumonia, a condition characterized predominantly by severe pneumonia. This disease, caused by the bacterium Legionella pneumophila, can quickly progress to critical pneumonia and is often associated with damage to multiple organs. As a result, it requires close attention in terms of clinical diagnosis and treatment. Omadacycline, a new type of tetracycline derivative belonging to the aminomethylcycline class of antibiotics, is a semi-synthetic compound derived from minocycline. Its key structural feature, the aminomethyl modification, allows omadacycline to overcome bacterial resistance and broadens its range of effectiveness against bacteria. Clinical studies have demonstrated that omadacycline is not metabolized in the body, and patients with hepatic and renal dysfunction do not need to adjust their dosage. This paper reports a case of successful treatment of Legionella pneumonia with omadacycline in a patient who initially did not respond to empirical treatment with moxifloxacin. The patient also experienced electrolyte disturbance, as well as dysfunction in the liver and kidneys, delirium, and other related psychiatric symptoms.

BACKGROUND: Infection by Legionella bacteria is a risk to elderly individuals in health care facilities and should be managed by preventing bacterial proliferation in internal water systems. Norwegian legislation calls for a mandatory Legionella-specific risk assessment with the subsequent introduction of an adapted water management programme. The present study investigates adherence to legislation and guidelines on Legionella control and prevention in Norwegian nursing homes.
METHODS: A cross-sectional survey was distributed to Norwegian municipalities to investigate the status of Legionella specific risk assessments of internal water distribution systems and the introduction of water management programmes in nursing homes.
RESULTS: A total of 55.1% (n = 228) of the participating nursing homes had performed Legionella-specific risk assessments, of which 55.3% (n = 126) stated that they had updated the risk assessment within the last year. 96.5% introduced a water management programme following a risk assessment, whereas 59.6% of the ones without a risk assessment did the same. Nursing homes with risk assessments were more likely to monitor Legionella levels than those without (61.2% vs 38.8%), to remove dead legs (44.7% vs 16.5%), and to select biocidal preventive treatment over hot water flushing (35.5% vs 4.6%).
CONCLUSIONS: This study presents novel insight into Legionella control in Norway, suggesting that adherence to mandatory risk assessment in nursing homes is moderate-low. Once performed, the risk assessment seems to be advantageous as an introduction to future Legionella prevention in terms of the scope and contents of the water management programme.

Legionella is an opportunistic waterborne pathogen that is difficult to eradicate in colonized drinking water pipes. Legionella control is further challenged by aging water infrastructure and lack of evidence-based guidance for building treatment. This study assessed multiple premise water remediation approaches designed to reduce Legionella pneumophila within a residential building located in an aging, urban drinking water system over a two-year period. Samples (n = 745) were collected from hot and cold-water lines and quantified via most probable number culture. Building-level treatment approaches included three single heat shocks, three single chemical shocks, and continuous low-level chemical disinfection in the potable water system. The building was highly colonized with L. pneumophila with 71 % L. pneumophila positivity. Single heat shocks had a statistically significant L. pneumophila reduction one day post treatment but no significant L. pneumophila reduction at one week, two weeks, and four weeks post treatment. The first two chemical shocks resulted in statistically significant L. pneumophila reduction at two days and four weeks post treatment, but there was a significant L. pneumophila increase at four weeks following the third chemical shock. Continuous low-level chemical disinfection resulted in statistically significant L. pneumophila reduction at ten weeks post treatment implementation. This demonstrates that in a building highly colonized with L. pneumophila, sustained remediation is best achieved using continuous low-level chemical treatment.

Legionella is an opportunistic waterborne pathogen that causes Legionnaires\' disease. It poses a significant public health risk, especially to vulnerable populations in health care facilities. It is ubiquitous in manufactured water systems and is transmitted via inhalation or aspiration of aerosols/water droplets generated from water fixtures (e.g., showers and hand basins). As such, the effective management of premise plumbing systems (building water systems) in health care facilities is essential for reducing the risk of Legionnaires\' disease. Chemical disinfection is a commonly used control method and chlorine-based disinfectants, including chlorine, chloramine, and chlorine dioxide, have been used for over a century. However, the effectiveness of these disinfectants in premise plumbing systems is affected by various interconnected factors that can make it challenging to maintain effective disinfection. This systematic literature review identifies all studies that have examined the factors impacting the efficacy and decay of chlorine-based disinfectant within premise plumbing systems. A total of 117 field and laboratory-based studies were identified and included in this review. A total of 20 studies directly compared the effectiveness of the different chlorine-based disinfectants. The findings from these studies ranked the typical effectiveness as follows: chloramine > chlorine dioxide > chlorine. A total of 26 factors were identified across 117 studies as influencing the efficacy and decay of disinfectants in premise plumbing systems. These factors were sorted into categories of operational factors that are changed by the operation of water devices and fixtures (such as stagnation, temperature, water velocity), evolving factors which are changed in-directly (such as disinfectant concentration, Legionella disinfectant resistance, Legionella growth, season, biofilm and microbe, protozoa, nitrification, total organic carbon(TOC), pH, dissolved oxygen(DO), hardness, ammonia, and sediment and pipe deposit) and stable factors that are not often changed(such as disinfectant type, pipe material, pipe size, pipe age, water recirculating, softener, corrosion inhibitor, automatic sensor tap, building floor, and construction activity). A factor-effect map of each of these factors and whether they have a positive or negative association with disinfection efficacy against Legionella in premise plumbing systems is presented. It was also found that evaluating the effectiveness of chlorine disinfection as a water risk management strategy is further complicated by varying disinfection resistance of Legionella species and the form of Legionella (culturable/viable but non culturable, free living/biofilm associated, intracellular replication within amoeba hosts). Future research is needed that utilises sensors and other approaches to measure these key factors (such as pH, temperature, stagnation, water age and disinfection residual) in real time throughout premise plumbing systems. This information will support the development of improved models to predict disinfection within premise plumbing systems. The findings from this study will inform the use of chlorine-based disinfection within premise plumbing systems to reduce the risk of Legionnaires disease.

Secondary disinfection aims to prevent microbial regrowth during distribution by maintaining disinfectant residuals in water systems. However, multi-factorial interactions contribute to free chlorine decay in distribution systems, and even more so in building plumbing. Assembling 1737 samples from nine large institutional buildings, a meta-analysis was conducted to determine whether building managers can actively rely on incoming free chlorine residuals to prevent in-building microbial amplification. Findings showed that free chlorine concentrations in first draws met the 0.2 mg/L common guide level in respectively 26 %, 6 % and 2 % of cold, tepid and hot water samples, whereas flushing for 2-60 min only significantly increased this ratio in cold water (83 %), without reaching background levels found in service lines. Free chlorine was significantly but weakly (R≤ 0.2) correlated to adenosine triphosphate, heterotrophic plate count and total and intact cell counts, thus evidencing that residuals contributed to decreased culturable and viable biomass. Detection of culturable Legionella pneumophila spanning over a 4-log distribution solely occurred when free chlorine levels were below 0.2 mg/L, but no such trend could be distinguished clearly for culturable Pseudomonas aeruginosa. Water temperatures below 20 °C and >60 °C also completely prevented L. pneumophila detection. Overall, the majority of elevated microbial counts were measured in distal sites and in tepid and hot water, where free chlorine is less likely to be present due to stagnation and increased temperature. Therefore, building managers cannot solely rely on this chemical barrier to mitigate bacterial growth in bulk water.