Decreasing Pasteurization Treatment Efficiency against Amoeba-Grown Legionella pneumophila-Recognized Public Health Risk Factor.

Legionellae are gram-negative bacteria most commonly found in freshwater ecosystems and purpose-built water systems. In humans, the bacterium causes Legionnaires' disease (LD) or a Pontiac fever. In this study, the different waters (drinking water, pool water, cooling towers) in which Legionella pneumophila has been isolated were studied to assess the possible risk of bacterial spreading in the population. The influence of physical and chemical parameters, and interactions with Acanthamoeba castellanii on L. pneumophila, were analyzed by Heterotrophic Plate Count, the Colony-forming units (CFU) methods, transmission electron microscopy (TEM), and Sequence-Based Typing (SBT) analysis. During the study period (2013-2019), a total of 1932 water samples were analyzed, with the average annual rate of Legionella-positive water samples of 8.9%, showing an increasing trend. The largest proportion of Legionella-positive samples was found in cooling towers and rehabilitation centers (33.9% and 33.3%, respectively). Among the isolates, L. pneumophila SGs 2-14 was the most commonly identified strain (76%). The survival of Legionella was enhanced in the samples with higher pH values, while higher electrical conductivity, nitrate, and free residual chlorine concentration significantly reduced the survival of Legionella. Our results show that growth in amoeba does not affect the allelic profile, phenotype, and morphology of the bacterium but environmental L. pneumophila becomes more resistant to pasteurization treatment.

Is a Proactive Approach to Controlling Legionella in the Environment Justified?

RESEARCH BACKGROUND: Legionella are Gram-negative bacteria that are ubiquitous in the natural environment. Contaminated water in man-made water systems is a potential source of transmission of legionnaires' disease. The aim of this study is to explore the prevalence of Legionella pneumophila in the drinking water distribution system (DWDS) of Primorje-Gorski Kotar (PGK) County, Croatia, for the period 2013-2019, coupled with the incidence of legionnaires' disease. A number of L. pneumophila-positive samples (>100 CFU/L), serogroup distribution and the degree of contamination of specific facilities (health and aged care, tourism, and sports) were assessed. Based on the obtained results, the reasoning for the implementation of a mandatory Legionella environmental surveillance program was assessed. EXPERIMENTAL APPROACH: Sample testing for Legionella was carried out according to the standard method for enumeration of this bacterium. A heterotrophic plate count (HPC) and Pseudomonas aeruginosa number were analysed along with the basic physicochemical indicators of drinking water quality. The research period was divided into two parts, namely, the 2013-2018 period (before implementation of the prevention program, after the outbreak of legionnaires' disease), and the year 2019 (proactive approach, no disease cases recorded). RESULTS AND CONCLUSION: During the 7-year observation period in PGK County, an increase in the number of samples tested for Legionella was found. An increase in Legionella-positive samples (particularly pronounced during the warmer part of the year) was recorded, along with a growing trend in the number of reported legionnaires' disease cases. In addition to hot water systems, the risk of Legionella colonisation also applies to cold water systems. Health and aged care facilities appear to be at highest risk. In addition to the higher proportion of positive samples and a higher degree of microbiological load in these facilities, the highest proportion of L. pneumophila SGs 2-14 was identified. Due to the diagnostic limitations of the applied tests, the number of legionnaires' disease cases is underdiagnosed. NOVELTY AND SCIENTIFIC CONTRIBUTION: The introduction of a mandatory preventive approach to monitoring Legionella in DWDS water samples, along with the definition of national criteria for the interpretation of the results will create the preconditions for diagnosis and adequate treatment of larger numbers of legionnaires' disease cases.

Parental Knowledge and Awareness Linked to Antibiotic Use and Resistance: Comparison of Urban and Rural Population in Croatia.

Purpose: To investigate the differences in parental knowledge, attitudes, and practice about antibiotic use and resistance among the urban and rural populations in Croatia. Materials and Methods: A cross-sectional study based on a structured questionnaire was distributed to 1,000 parents of children attending 11 elementary schools of Primorsko-Goranska County in 2017. Results: The overall response rate was 65.1% (651/1,000)-50.6% (253/500) in urban and 79.6% (398/500) in rural population. Urban parents had a higher overall knowledge about antibiotics (p < 0.001), while urban and rural parents held mostly similar knowledge and attitudes related to antibiotic use when split into individual statements (p > 0.05). Age, education, income, work, and family member working in a health-related field were significantly related with the overall knowledge about antibiotics. In the previous year, 28.2% of children and 28.9% of parents reported using an antibiotic. Croatian parents had a high level of trust in doctors' antibiotic-prescribing practices (96.3% reported trusting the doctors' decision not to prescribe antibiotics, 93.5% to prescribe antibiotics) and high awareness of antimicrobial resistance (94.8%). The public's misconception regarding the terms "bacteria" and "virus" was found in 15.5% of parents. The source of information about antimicrobial resistance was television (60.4%), internet (57.1%), newspapers (44.2%), and medical professionals (30.9%). Conclusions: Although the knowledge about antibiotics was higher in urban parents, it was not reflected on the level of antibiotic consumption. There are indications that medical professionals should be more involved in communicating the problems of antibiotic use and resistance to patients.