Controlling Legionella and Pseudomonas aeruginosa re-growth in therapeutic spas: implementation of physical disinfection treatments, including UV/ultrafiltration, in a respiratory hydrotherapy system

GVPC Medium Manufactured without Oxygen Improves the Growth of Legionella spp. and Exhibits Enhanced Selectivity Properties

Glycine-vancomycin-polymyxin-cycloheximide agar (GVPC) is a recommended medium for the detection of Legionella spp. in water samples. However, its quality could be improved in terms of recovery of Legionella spp. and selectivity properties. Modifications were introduced in GVPC manufacture: autoclaving conditions (115°C, 15 min) and atmosphere during component-stirring (removal of oxygen and N₂ injection). The use of softer autoclaving conditions (115°C, 15 min) improved the growth of Legionella anisa by the spiral method and Legionella pneumophila after membrane filtration. The medium manufactured with O₂ removal and autoclaving for 15 min at 115°C allowed a faster growth of L. pneumophila (colonies visible at day 2) and a notable increase of L. anisa growth (colonies appearing at day 3, and statistically significant numbers of CFU at day 5). After 3 to 5 days of incubation, the improved media showed higher selectivity properties, particularly for Enterococcus faecalis ATCC 29212 and Pseudomonas aeruginosa ATCC 9027. A further improvement was achieved by the addition of N₂ during ingredient stirring, leading to a statistically significant faster growth of L. pneumophila at days 2 and 3 and L. anisa at day 3. Selectivity properties were also enhanced, resulting in the complete inhibition of both E. faecalis strains and Escherichia coli and complete-partial inhibition of P. aeruginosa. Oxygen removal during GVPC manufacture using a vacuum pump system promotes the growth of L. pneumophila and L. anisa, and markedly inhibits the growth of E. coli, P. aeruginosa, and E. faecalis. IMPORTANCE Currently, GVPC is a recommended medium for the detection of Legionella spp. in water samples. However, recovery of Legionella spp. and selectivity properties can be improved. GVPC medium manufactured without oxygen improved the growth of Legionella pneumophila and Legionella anisa. Oxygen removal during GVPC manufacture also improved selectivity properties. A further improvement was achieved by the addition of N₂ during ingredient stirring, leading to a faster growth of L. pneumophila at days 2 and 3 and L. anisa at day 3 and enhancement of selectivity properties. The introduction of the modified GVPC medium in routine practice can allow a better detection of Legionella spp. in water samples.

Disinfection of Therapeutic Spa Waters: Applicability of Sodium Hypochlorite and Hydrogen Peroxide-Based Disinfectants

The microbial water quality of therapeutic pools operating without disinfection is recurrently compromised, posing a risk to bathers’ health. The complex composition of such waters and the sensitivity of their therapeutic components hinder the use of traditional chlorine-based disinfectants. The present study aimed to investigate the applicability of a hydrogen peroxide-based disinfectant in therapeutic water in comparison with hypochlorite. Disinfection efficacy, byproduct formation, and the fate of therapeutic components were tested for both disinfectants under laboratory conditions, applying different doses and contact times. Disinfection efficacy was found to be matrix-dependent, especially that of hydrogen peroxide against Pseudomonas aeruginosa (a 10- to 1000-fold difference). Hypochlorite treatment presented a significant chemical risk through the generation of byproducts, mainly brominated and iodinated compounds and combined chlorine. Of the alleged therapeutic components, sulfide ions were eliminated (≥86% loss) by both disinfectants, and hypochlorite reacted with iodide ions as well (≥70% removal). Based on their composition, only 2% of Hungarian therapeutic waters can be treated by chlorination due to high concentrations of ammonia and/or organic compounds. Hydrogen peroxide is applicable to 82% of the waters, as the presence of sulfide ions is the only limiting factor. Due to the matrix effect, close control of residual disinfectant concentration is necessary to ensure microbial safety.

Disinfection of therapeutic water - balancing risks against benefits: case study of Hungarian therapeutic baths on the effects of technological steps and disinfection on therapeutic waters

Thermal therapeutic pools in most countries are operated in a manner similar to swimming pools: with water circulation, filtration and disinfection. However, in some countries, including Hungary, therapeutic pools are traditionally not treated this way, in order to preserve the therapeutic qualities of the water. However, dilution and frequent water replacement applied in these pools are often insufficient to ensure adequate microbial water quality, posing a risk of infection to the bathers. In the present case study, the impact of water treatment (including chemical disinfection by hypochlorite or hydrogen peroxide) was investigated on the therapeutic components of the water in seven Hungarian spas of various water composition. Microbial quality was improved by both disinfectants, but hypochlorite reduced the concentration of the therapeutic components sulfide, bromide, and iodide ions by 40-99%, and high levels of disinfection by-products were observed. Hydrogen peroxide only affected sulfide ion (91% reduction). Other technological steps (e.g., transport or cooling by dilution) were found to have significant impact on composition, often outweighing the effect of disinfection. The current case study demonstrated that thermal waters may be treated and disinfected with minimal loss of the therapeutic compounds, if an adequate treatment procedure is selected based on the water composition.

Causes, Factors, and Control Measures of Opportunistic Premise Plumbing Pathogens—A Critical Review

This review critically analyses the chemical and physical parameters that influence the occurrence of opportunistic pathogens in the drinking water distribution system, specifically in premise plumbing. A comprehensive literature review reveals significant impacts of water age, disinfectant residual (type and concentration), temperature, pH, and pipe materials. Evidence suggests that there is substantial interplay between these parameters; however, the dynamics of such relationships is yet to be elucidated. There is a correlation between premise plumbing system characteristics, including those featuring water and energy conservation measures, and increased water quality issues and public health concerns. Other interconnected issues exacerbated by high water age, such as disinfectant decay and reduced corrosion control efficiency, deserve closer attention. Some common features and trends in the occurrence of opportunistic pathogens have been identified through a thorough analysis of the available literature. It is proposed that the efforts to reduce or eliminate their incidence might best focus on these common features.

Opportunistic Premise Plumbing Pathogens. A Potential Health Risk in Water Mist Systems Used as a Cooling Intervention

Water mist systems (WMS) are used for evaporative cooling in public areas. The health risks associated with their colonization by opportunistic premise plumbing pathogens (OPPPs) is not well understood. To advance the understanding of the potential health risk of OPPPs in WMS, biofilm, water and bioaerosol samples (n = 90) from ten (10) WMS in Australia were collected and analyzed by culture and polymerase chain reaction (PCR) methods to detect the occurrence of five representative OPPPs: Legionella pneumophila, Pseudomonas aeruginosa, Mycobacterium avium, Naegleria fowleri and Acanthamoeba. P. aeruginosa (44%, n = 90) occurred more frequently in samples, followed by L. pneumophila serogroup (Sg) 2–14 (18%, n = 90) and L. pneumophila Sg 1 (6%, n = 90). A negative correlation between OPPP occurrence and residual free chlorine was observed except with Acanthamoeba, rs (30) = 0.067, p > 0.05. All detected OPPPs were positively correlated with total dissolved solids (TDS) except with Acanthamoeba. Biofilms contained higher concentrations of L. pneumophila Sg 2–14 (1000–3000 CFU/mL) than water samples (0–100 CFU/mL). This study suggests that WMS can be colonized by OPPPs and are a potential health risk if OPPP contaminated aerosols get released into ambient atmospheres.

Legionellosis in Japan: A Self-inflicted Wound?

Legionellosis is a serious bacterial infection characterized by atypical pneumonia primarily due to infection with Legionella pneumophila, and bathing can be a potential cause of this infection. Legionellosis was first identified in 1977, and it is caused by Gram-negative bacteria belonging to the genus Legionella. Legionellosis remains an important public health threat, particularly in Japan, where the population is rapidly aging, thereby becoming more at risk of developing severe disease and accompanying life-threatening pneumonia. The bacteria are most commonly transmitted via the inhalation of contaminated aerosols produced and broadcast via water sprays, jets or mists. Infection can also occur via the aspiration of contaminated water or ice, or through inhalation of contaminated dust. Because the signs and symptoms of Legionnaires' disease (LD), as well as radiographic imaging are similar to pneumonia caused by other pathogens, a specific diagnostic test is required, such as a urine antigen detection test. Six clinical and laboratory parameters, a high body temperature, a non-productive cough, low serum sodium and platelet counts, and high lactate dehydrogenase (LDH) and c-reactive protein concentrations can be used to reliably predict the likelihood of LD. The first choices for chemotherapy are fluoroquinolone and macrolide antibiotic drugs. The main goals of LD prevention measures are 1) the prevention of microbial growth and biofilm formation, 2) the removal of all biofilm formed on equipment and in facilities, 3) minimizing aerosol splash and spread, and 4) minimizing bacterial contamination from external sources. It is apparent that, in Japan, where hot spring (onsen) bathing is common among aged people, strict regulations need to be in place - and enforced - to ensure that all Japanese onsens and spas provide a safe environment and undertake regular, effective infection control practices.

Legionellosis Associated with Recreational Waters: A Systematic Review of Cases and Outbreaks in Swimming Pools, Spa Pools, and Similar Environments

Legionella spp. is widespread in many natural and artificial water systems, such as hot water distribution networks, cooling towers, and spas. A particular risk factor has been identified in the use of whirlpools and hot tubs in spa facilities and public baths. However, there has been no systematic synthesis of the published literature reporting legionellosis cases or outbreaks related to swimming/spa pools or similar environments used for recreational purposes (hot springs, hot tubs, whirlpools, natural spas). This study presents the results of a systematic review of the literature on cases and outbreaks associated with these environments. Data were extracted from 47 articles, including 42 events (17 sporadic cases and 25 outbreaks) and 1079 cases, 57.5% of which were diagnosed as Pontiac fever, without any deaths, and 42.5% were of Legionnaires' disease, with a fatality rate of 6.3%. The results are presented in relation to the distribution of Legionella species involved in the events, clinical manifestations and diagnosis, predisposing conditions in the patients, favourable environmental factors, and quality of the epidemiological investigation, as well as in relation to the different types of recreational water sources involved. Based on the epidemiological and microbiological criteria, the strength of evidence linking a case/outbreak of legionellosis with a recreational water system was classified as strong, probable, and possible; in more than half of the events the resulting association was strong.

Assessing natural mineral water microbiology quality in the absence of cultivable pathogen bacteria

Italian Directives recommend the good quality of natural mineral waters but literature data assert a potential risk from microorganisms colonizing wellsprings and mineral water bottling plants. We evaluated the presence of microorganisms in spring waters (SW) and bottled mineral waters (BMW) samples. Routine microbiological indicators, additional microorganisms like Legionella spp., Nontuberculous mycobacteria (NTM) and amoebae (FLA) were assessed in 24 SW and 10 BMW samples performing cultural and molecular methods. In 33 out of 34 samples, no cultivable bacteria ≥10 CFU/L was found. Cultivable FLA were detected in 50% of water samples. qPCR showed the presence of Legionella qPCR units in 24% of samples (from 1.1 × 10² to 5.8 × 10² qPCR units/L) and NTM qPCR units in 18% of samples (from 1 × 10² to 1 × 10⁵ qPCR units/L). Vermamoeba vermiformis and Acanthamoeba polyphaga were recovered respectively in 70% of BMW samples (counts from 1.3 × 10³ to 1.2 × 10⁵ qPCR units/L) and 42% of SW samples (from 1.1 × 10³ to 1.3 × 10⁴ qPCR units/L). Vahlkampfia spp. was detected in 42% of SW and 70% of BMW samples (from 1.2 × 10³ to 1.2 × 10⁵ qPCR units/L). Considering the presence of FLA, we underline the importance of a wider microbiological risk assessment in natural mineral waters despite the absence of cultivable bacteria.

The presence of biofilm forming microorganisms on hydrotherapy equipment and facilities

Hydrotherapy equipment provides a perfect environment for the formation and growth of microbial biofilms. Biofilms may reduce the microbiological cleanliness of hydrotherapy equipment and harbour opportunistic pathogens and pathogenic bacteria. The aims of this study were to investigate the ability of microorganisms that colonize hydrotherapy equipment to form biofilms, and to assess the influence of temperature and nutrients on the rate of biofilm formation. Surface swab samples were collected from the whirlpool baths, inhalation equipment and submerged surfaces of a brine pool at the spa center in Ciechocinek, Poland. We isolated and identified microorganisms from the swab samples and measured their ability to form biofilms. Biofilm formation was observed at a range of temperatures, in both nutrient-deficient and nutrient-rich environments. We isolated and identified microorganisms which are known to form biofilms on medical devices (e.g. Stenotrophomonas maltophilia). All isolates were classified as opportunistic pathogens, which can cause infections in humans with weakened immunity systems. All isolates showed the ability to form biofilms in the laboratory conditions. The potential for biofilm formation was higher in the presence of added nutrients. In addition, the hydrolytic activity of the biofilm was connected with the presence of nutrients.