Olga Valcina - Academia.edu (original) (raw)

Papers by Olga Valcina

publication.editionName, 2013

The prevention and control of legionellosis in water supply systems involves environmental compre... more The prevention and control of legionellosis in water supply systems involves environmental comprehensive sampling. Our aim was to investigate occurrence of Legionella spp. in water supply systems in different administrative districts of Riga, and to find out if there exists a correlation between Legionella spp. positive cases and water source, type of sample, sampling point and temperature of hot water, received at the point of consumption. A total 467 samples were collected from 94 apartment buildings in different administrative districts of Riga. Water samples n=302) were taken from heating units in apartment buildings, from taps and shower heads in private apartments and sediment samples were taken in private apartments (n=165). Water temperature was measured during sampling. L.pneumophila was found in 50 out of 94 apartment buildings (53%). From all Legionella spp. positive samples, 19% represented L.pneumophila serogroup 1 and 81% L.pneumophila serogroup 2.-14.(15.). L.pneumophila was found in 44% of hot water samples from heating units and in 52% of hot water samples from private apartments. Data analysis confirmed observation that temperature of hot water significantly affects the frequency of L.pneumophila positive cases (p<0,05). L.pneumophila was found in 5% of cold water samples from heating units and in 17% of cold water samples from private apartments. L.pneumophila was isolated from 4% of sediment samples. However, investigation of sediment samples did not show presence of Legionella spp. in 79% of cases when at least one water sample from the same location was L.pneumophila positive.

Clinical Mass Spectrometry, Apr 1, 2020

Rapid identification of methicillin-resistant Staphylococcus could ensure appropriate medical car... more Rapid identification of methicillin-resistant Staphylococcus could ensure appropriate medical care. A total of 409 Staphylococcus spp. strains were used to develop a reliable MALDI-TOF method for species identification. We tested twelve S. aureus strains to compare three different sample preparation methods and the reproducibility of the methicillin-resistant m/z 2414 ± 2 indicator peak with direct method in triplicate. A total of 65 Staphylococcus spp. strains (including 37 methicillin-resistant strains) from clinical and hospital environment isolates were used to confirm the presence of phenol-soluble modulin (PSM-mec) peptide. All 272 S. aureus strains from 409 samples were correctly identified at species level by MALDI-TOF. The samples prepared by three methods gave spectra with differences in the intensities and presence of certain peaks. The PSM-mec peak was not visible after the extraction method. The peak m/z 2414 ± 2 was only detected in 61% of the methicillin-resistant strains and in none of the methicillinsensitive strains. The peak reproducibility for the five analyzed S. aureus strains showing the peak at m/z 2414 ± 2 was 87%. The delta-toxin was observed in 49 out of 65 samples regardless of methicillin susceptibility, as well as in all the samples exhibiting the PSM-mec peak. The peak m/z 2414 ± 2 is specific to methicillin-resistant strains carrying the mecA gene, but the absence of peak m/z 2414 ± 2 does not exclude the possibility of resistance to methicillin. Thus, implementing MALDI-TOF analysis in routine laboratory work, especially with clinical samples, would in many cases provide rapid warning about the presence of methicillin-resistant strains.

publication.editionName, 2013

Legionellae are found in freshwater environments or wet soil, but the major reservoirs are man-ma... more Legionellae are found in freshwater environments or wet soil, but the major reservoirs are man-made aquatic environments, particularly warm water systems. Our aim was to study the occurrence of Legionella contamination in hot potable water supply systems in apartment and public buildings. Correlations between Legionella spp. positive cases and water source, sampling point and temperature of hot water at the point of consumption were studied. A total of 149 hot water samples were collected in 16 cities and districts of Latvia. Only Legionella pneumophila was isolated. L. pneumophila was found in 63 out of 149 (42%) hot water samples. From all Legionella spp. positive samples, 17% represented L. pneumophila serogroup 1 and 78% L. pneumophila serogroups 2-14 (15). In 5% of Legionella spp. positive samples, both serogroups 1 and 2-14(15) were isolated. Statistically significant differences were observed in the distribution of L. pneumophila serogroup 1 in samples from various water sources. L. pneumophila was found in 45% of samples from private apartments and in 27% of samples from public buildings. Data analysis confirmed that the temperature of hot water significantly affects the frequency of L. pneumophila positive cases (p < 0.05). Data showed that 85% of consumers received hot water at a temperature below 50 °C.

Proceedings of the Latvian Academy of Sciences. Section B, Natural, Exact and Applied Sciences, Apr 1, 2021

Acinetobacter baumannii is an aerobic gram-negative opportunistic bacterial pathogen, an emerging... more Acinetobacter baumannii is an aerobic gram-negative opportunistic bacterial pathogen, an emerging cause of healthcare-associated infections, associated with increased morbidity, mortality and healthcare costs. It has been widely found in the hospital environment, exhibiting high resistance to antimicrobials, affecting the spread of healthcare-associated infections and preventing effective infection control. The role of virulence factors in the pathogenesis of A. baumannii related human infections remains unclear. Therefore, molecular testing of pathogenic bacteria is an important tool for improving infection control measures against A. baumannii with combined resistance. The aim of this study was to analyse A. baumannii infection cases, antimicrobial resistance profiles and to characterise the genetic heterogeneity of isolates. In general, outbreaks occurring in hospitals are presumed to be clonal, with patient-to-patient transmission of essentially identical strains. Treatment decisions are based on a combination of in vitro susceptibility assays and empirical results based on patient outcomes.

Proceedings of the Latvian Academy of Sciences. Section B, Natural, Exact and Applied Sciences, Aug 1, 2016

Contributed by Ludmila Vîksna Legionella pneumophila is an environmental pathogen of engineered w... more Contributed by Ludmila Vîksna Legionella pneumophila is an environmental pathogen of engineered water systems that can cause different forms of legionellosis-from mild fever to potentially lethal pneumonia. Low concentrations of legionellae in natural habitats can increase markedly in engineered hot water systems where water temperatures are below 55°C. In the current study, we aimed to investigate the influence of sampling season, hot water temperature and sampling protocol on occurrence of L. pneumophila. A total of 120 hot water samples from 20 apartment buildings were collected in two sampling periods-winter 2014 (n = 60) and summer 2015 (n = 60). Significantly higher occurrence of L. pneumophila was observed in summer 2015. Significant differences in temperature for negative and positive samples were not observed, which can be explained by low water temperatures at the point of water consumption. Temperature above 55°C was observed only once, for all other sampling events it ranged from 14°C to 53°C.

Proceedings of the Latvian Academy of Sciences. Section B, Natural, Exact and Applied Sciences, Aug 1, 2016

Ready-to-eat (RTE) foods are challenging for food business operators as they need to remain quali... more Ready-to-eat (RTE) foods are challenging for food business operators as they need to remain qualitative and safe for consumers. However, consumers tend to choose them more and more often because of fast and easy handling. The highest risk from RTE foods is microbiological contamination, particularly for vulnerable groups like children, elderly, and pregnant women. The aim of the research was to assess the microbiological quality of RTE meat and fish products to highlight possible risks for consumers. A total of 15 984 analyses performed on RTE meat and fish products were included in this study. It was found that RTE meat and fish product samples representative of the market in Latvia in the period 2012-2015 had high microbiological quality and only in rare cases was contamination with hygiene indicatororganisms (coliforms and Escherichia coli) and pathogens (Salmonella spp., Listeria monocytogenes, Staphylococcus aureus, and sulphite-reducing clostridia) detected. However, it is important to pay attention to customer habits of cooking and preparing RTE foods as well-thermal processing for products intended to be used cooked, use before expiration date and adequate storage rules for products, as these have important regarding microbiological risks for health.

Parasitology Research, Jul 5, 2018

Acanthamoeba are free-living amoebae found in various ecological environments, and they are major... more Acanthamoeba are free-living amoebae found in various ecological environments, and they are major microbial predators. Some Acanthamoeba species can cause keratitis, granulomatous amoebic encephalitis, and infections of the organs. This is the first study in Latvia describing Acanthamoeba detection by molecular techniques and genotyping using tap water from different sources. An 18S rRNA gene investigation of the 20 Acanthamoeba isolates suggested that 19 belonged to the hazardous T4 genotype and one sample was T12. The results indicate that tap water in Latvia may be a source of Acanthamoeba that is potentially pathogenic to humans. All obtained sequences were submitted to the GenBank database under the following accession numbers: MG386295-MG386314.

Proceedings of the Latvian Academy of Sciences, 2017

International Journal of Environmental Research and Public Health, Dec 22, 2015

Continuous environmental exposure of humans to Legionella may induce immune responses and generat... more Continuous environmental exposure of humans to Legionella may induce immune responses and generation of antibodies. The aim of this study was to investigate the seroprevalence of Legionella pneumophila serogroups (SG) 1-6 in the general healthy population and identify the associated host-related and environmental risk factors. L. pneumophila SG 1-6 seroprevalence among a total of 2007 blood samples collected from healthy donors was 4.8%. Seroprevalence was higher in women (5.9%) than men (3.3%) and in areas with a larger number of inhabitants, ranging from 3.5% in rural regions to 6.8% in the capital, Riga. Blood samples from inhabitants of apartment buildings tested positive for L. pneumophila in more cases (5.8%) compared to those from inhabitants of single-family homes (2.7%). Residents of buildings with a municipal hot water supply system were more likely to be seropositive for L. pneumophila (OR = 3.16, 95% CI 1.26-7.91). Previous episodes of fever were additionally identified as a risk factor (OR = 2.42, 95% CI 1.43-4.1). In conclusion, centralized hot water supply, female gender and previous episodes of fever were determined as the main factors associated with L. pneumophila seropositivity in our study population.

Medicina-lithuania, Aug 15, 2019

Background and Objectives: Legionella is one of the most important water-related pathogens. Insid... more Background and Objectives: Legionella is one of the most important water-related pathogens. Inside the water supply systems and the biofilms, Legionella interact with other bacteria and free-living amoeba (FLA). Several amoebas may serve as hosts for bacteria in aquatic systems. This study aimed to investigate the co-occurrence of Legionella spp. and FLA in drinking water supply systems. Materials and Methods: A total of 268 water samples were collected from apartment buildings, hotels, and public buildings. Detection of Legionella spp. was performed in accordance with ISO 11731:2017 standard. Three different polymerase chain reaction (PCR) protocols were used to identify FLA. Results: Occurrence of Legionella varied from an average of 12.5% in cold water samples with the most frequent occurrence observed in hot water, in areas receiving untreated groundwater, where 54.0% of the samples were Legionella positive. The occurrence of FLA was significantly higher. On average, 77.2% of samples contained at least one genus of FLA and, depending on the type of sample, the occurrence of FLA could reach 95%. In the samples collected during the study, Legionella was always isolated along with FLA, no samples containing Legionella in the absence of FLA were observed. Conclusions: The data obtained in our study can help to focus on the extensive distribution, close interaction, and long-term persistence of Legionella and FLA. Lack of Legionella risk management plans and control procedures may promote further spread of Legionella in water supply systems. In addition, the high incidence of Legionella-related FLA suggests that traditional monitoring methods may not be sufficient for Legionella control.

Pathogens

Legionella is an opportunistic pathogen with a biphasic life cycle that occasionally infects huma... more Legionella is an opportunistic pathogen with a biphasic life cycle that occasionally infects humans. The aim of the study was to assess the distribution of virulence genes and genetic diversity among L. pneumophila isolated from water supply systems of residential buildings in Latvia. In total, 492 water samples from 200 residential buildings were collected. Identification of Legionella spp. was performed according to ISO 11731, and 58 isolates were subjected to whole-genome sequencing. At least one Legionella-positive sample was found in 112 out of 200 apartment buildings (56.0%). The study revealed extensive sequence-type diversity, where 58 L. pneumophila isolates fell into 36 different sequence types. A total of 420 virulence genes were identified, of which 260 genes were found in all sequenced L. pneumophila isolates. The virulence genes enhC, htpB, omp28, and mip were detected in all isolates, suggesting that adhesion, attachment, and entry into host cells are enabled for all ...

Microorganisms

Legionella is one of the most important waterborne pathogens that can lead to both outbreaks and ... more Legionella is one of the most important waterborne pathogens that can lead to both outbreaks and sporadic cases. The majority of travel-associated Legionnaires’ disease (TALD) cases are contracted during hotel stays. The aim of this study was to evaluate the prevalence and genetic diversity of Legionella spp. in hotel water supply systems in Latvia. In total, 834 hot water samples were collected from the water systems of 80 hotels in Latvia. At least one Legionella spp. positive sample was detected in 47 out of 80 hotels (58.8%). Overall, 235 out of 834 samples (28.2%) were Legionella spp. positive. The average hot water temperature in Latvian hotels was 49.8 °C. The most predominant L. pneumophila serogroup (SG) was SG3 which was found in 113 (49.8%) positive samples from 27 hotels. For 79 sequenced L. pneumophila isolates, 21 different sequence types (ST) were obtained, including 3 new types—ST2582, ST2579, and ST2580. High Legionella contamination and high genetic diversity were ...

International Journal of Food Microbiology

Frontiers in Microbiology

Coronary artery disease (CAD) is the most common cardiovascular disease (CVD) and the main leadin... more Coronary artery disease (CAD) is the most common cardiovascular disease (CVD) and the main leading cause of morbidity and mortality worldwide, posing a huge socio-economic burden to the society and health systems. Therefore, timely and precise identification of people at high risk of CAD is urgently required. Most current CAD risk prediction approaches are based on a small number of traditional risk factors (age, sex, diabetes, LDL and HDL cholesterol, smoking, systolic blood pressure) and are incompletely predictive across all patient groups, as CAD is a multi-factorial disease with complex etiology, considered to be driven by both genetic, as well as numerous environmental/lifestyle factors. Diet is one of the modifiable factors for improving lifestyle and disease prevention. However, the current rise in obesity, type 2 diabetes (T2D) and CVD/CAD indicates that the “one-size-fits-all” approach may not be efficient, due to significant variation in inter-individual responses. Recent...

The prevention and control of legionellosis in water supply systems involves environmental compre... more The prevention and control of legionellosis in water supply systems involves environmental comprehensive sampling. Our aim was to investigate occurrence of Legionella spp. in water supply systems in different administrative districts of Riga, and to find out if there exists a correlation between Legionella spp. positive cases and water source, type of sample, sampling point and temperature of hot water, received at the point of consumption. A total 467 samples were collected from 94 apartment buildings in different administrative districts of Riga. Water samples n=302) were taken from heating units in apartment buildings, from taps and shower heads in private apartments and sediment samples were taken in private apartments (n=165). Water temperature was measured during sampling. L.pneumophila was found in 50 out of 94 apartment buildings (53%). From all Legionella spp. positive samples, 19% represented L.pneumophila serogroup 1 and 81% L.pneumophila serogroup 2.-14.(15.). L.pneumoph...

Medicina, 2019

Background and Objectives: Legionella is one of the most important water-related pathogens. Insid... more Background and Objectives: Legionella is one of the most important water-related pathogens. Inside the water supply systems and the biofilms, Legionella interact with other bacteria and free-living amoeba (FLA). Several amoebas may serve as hosts for bacteria in aquatic systems. This study aimed to investigate the co-occurrence of Legionella spp. and FLA in drinking water supply systems. Materials and Methods: A total of 268 water samples were collected from apartment buildings, hotels, and public buildings. Detection of Legionella spp. was performed in accordance with ISO 11731:2017 standard. Three different polymerase chain reaction (PCR) protocols were used to identify FLA. Results: Occurrence of Legionella varied from an average of 12.5% in cold water samples with the most frequent occurrence observed in hot water, in areas receiving untreated groundwater, where 54.0% of the samples were Legionella positive. The occurrence of FLA was significantly higher. On average, 77.2% of sa...

Food Control, 2017

Spices and herbs can contain toxin-producing bacteria and moulds, which can cause health problems... more Spices and herbs can contain toxin-producing bacteria and moulds, which can cause health problems for consumers and contribute to food spoilage and shelf-life reduction. The aims of the present work were (i) to determine the occurence and levels of B. cereus and moulds; (ii) to charactize the incidence and diversity of B. cereus emetic toxin (ces, CER), and diarrhoeal toxin-encoding genes (entFM, nheA, hblC, cytK) and toxigenic potential of Hbl toxin-producing B. cereus strains. Black ground pepper samples showed the most contamination with the highest concentration of B. cereus 2.49 log 10 CFU/g. Moreover, cumin contained the most prominent mould concentration level of 3.6 log 10 CFU/g. The most common moulds were Aspergillus and Penicillium spp. Compared to packaging type, all products acquired from the local market, except curry for B. cereus, exchibited high concentrations of B. cereus and moulds. Four genes were identified e 96% of B. cereus strains contained entFM, 94% nheA, 56% hblC, 42% cytK. None of the samples contained emetic toxin-encoding genes (ces, CER). Toxigenic potential of Hbl toxin was found in 72% of B. cereus strains. Different temperature, moisture levels and hygiene practices were observed at places of sale in local markets thus facilitating contamination and development of moulds. Moreover, the presence of B. cereus and its ability to produce toxins in spices and herbs, may suggest the need to establish microbiological criteria for mould and spore-forming bacteria in spices and herbs.

publication.editionName, 2013

The prevention and control of legionellosis in water supply systems involves environmental compre... more The prevention and control of legionellosis in water supply systems involves environmental comprehensive sampling. Our aim was to investigate occurrence of Legionella spp. in water supply systems in different administrative districts of Riga, and to find out if there exists a correlation between Legionella spp. positive cases and water source, type of sample, sampling point and temperature of hot water, received at the point of consumption. A total 467 samples were collected from 94 apartment buildings in different administrative districts of Riga. Water samples n=302) were taken from heating units in apartment buildings, from taps and shower heads in private apartments and sediment samples were taken in private apartments (n=165). Water temperature was measured during sampling. L.pneumophila was found in 50 out of 94 apartment buildings (53%). From all Legionella spp. positive samples, 19% represented L.pneumophila serogroup 1 and 81% L.pneumophila serogroup 2.-14.(15.). L.pneumophila was found in 44% of hot water samples from heating units and in 52% of hot water samples from private apartments. Data analysis confirmed observation that temperature of hot water significantly affects the frequency of L.pneumophila positive cases (p<0,05). L.pneumophila was found in 5% of cold water samples from heating units and in 17% of cold water samples from private apartments. L.pneumophila was isolated from 4% of sediment samples. However, investigation of sediment samples did not show presence of Legionella spp. in 79% of cases when at least one water sample from the same location was L.pneumophila positive.

Clinical Mass Spectrometry, Apr 1, 2020

Rapid identification of methicillin-resistant Staphylococcus could ensure appropriate medical car... more Rapid identification of methicillin-resistant Staphylococcus could ensure appropriate medical care. A total of 409 Staphylococcus spp. strains were used to develop a reliable MALDI-TOF method for species identification. We tested twelve S. aureus strains to compare three different sample preparation methods and the reproducibility of the methicillin-resistant m/z 2414 ± 2 indicator peak with direct method in triplicate. A total of 65 Staphylococcus spp. strains (including 37 methicillin-resistant strains) from clinical and hospital environment isolates were used to confirm the presence of phenol-soluble modulin (PSM-mec) peptide. All 272 S. aureus strains from 409 samples were correctly identified at species level by MALDI-TOF. The samples prepared by three methods gave spectra with differences in the intensities and presence of certain peaks. The PSM-mec peak was not visible after the extraction method. The peak m/z 2414 ± 2 was only detected in 61% of the methicillin-resistant strains and in none of the methicillinsensitive strains. The peak reproducibility for the five analyzed S. aureus strains showing the peak at m/z 2414 ± 2 was 87%. The delta-toxin was observed in 49 out of 65 samples regardless of methicillin susceptibility, as well as in all the samples exhibiting the PSM-mec peak. The peak m/z 2414 ± 2 is specific to methicillin-resistant strains carrying the mecA gene, but the absence of peak m/z 2414 ± 2 does not exclude the possibility of resistance to methicillin. Thus, implementing MALDI-TOF analysis in routine laboratory work, especially with clinical samples, would in many cases provide rapid warning about the presence of methicillin-resistant strains.

publication.editionName, 2013

Legionellae are found in freshwater environments or wet soil, but the major reservoirs are man-ma... more Legionellae are found in freshwater environments or wet soil, but the major reservoirs are man-made aquatic environments, particularly warm water systems. Our aim was to study the occurrence of Legionella contamination in hot potable water supply systems in apartment and public buildings. Correlations between Legionella spp. positive cases and water source, sampling point and temperature of hot water at the point of consumption were studied. A total of 149 hot water samples were collected in 16 cities and districts of Latvia. Only Legionella pneumophila was isolated. L. pneumophila was found in 63 out of 149 (42%) hot water samples. From all Legionella spp. positive samples, 17% represented L. pneumophila serogroup 1 and 78% L. pneumophila serogroups 2-14 (15). In 5% of Legionella spp. positive samples, both serogroups 1 and 2-14(15) were isolated. Statistically significant differences were observed in the distribution of L. pneumophila serogroup 1 in samples from various water sources. L. pneumophila was found in 45% of samples from private apartments and in 27% of samples from public buildings. Data analysis confirmed that the temperature of hot water significantly affects the frequency of L. pneumophila positive cases (p < 0.05). Data showed that 85% of consumers received hot water at a temperature below 50 °C.

Proceedings of the Latvian Academy of Sciences. Section B, Natural, Exact and Applied Sciences, Apr 1, 2021

Acinetobacter baumannii is an aerobic gram-negative opportunistic bacterial pathogen, an emerging... more Acinetobacter baumannii is an aerobic gram-negative opportunistic bacterial pathogen, an emerging cause of healthcare-associated infections, associated with increased morbidity, mortality and healthcare costs. It has been widely found in the hospital environment, exhibiting high resistance to antimicrobials, affecting the spread of healthcare-associated infections and preventing effective infection control. The role of virulence factors in the pathogenesis of A. baumannii related human infections remains unclear. Therefore, molecular testing of pathogenic bacteria is an important tool for improving infection control measures against A. baumannii with combined resistance. The aim of this study was to analyse A. baumannii infection cases, antimicrobial resistance profiles and to characterise the genetic heterogeneity of isolates. In general, outbreaks occurring in hospitals are presumed to be clonal, with patient-to-patient transmission of essentially identical strains. Treatment decisions are based on a combination of in vitro susceptibility assays and empirical results based on patient outcomes.

Proceedings of the Latvian Academy of Sciences. Section B, Natural, Exact and Applied Sciences, Aug 1, 2016

Contributed by Ludmila Vîksna Legionella pneumophila is an environmental pathogen of engineered w... more Contributed by Ludmila Vîksna Legionella pneumophila is an environmental pathogen of engineered water systems that can cause different forms of legionellosis-from mild fever to potentially lethal pneumonia. Low concentrations of legionellae in natural habitats can increase markedly in engineered hot water systems where water temperatures are below 55°C. In the current study, we aimed to investigate the influence of sampling season, hot water temperature and sampling protocol on occurrence of L. pneumophila. A total of 120 hot water samples from 20 apartment buildings were collected in two sampling periods-winter 2014 (n = 60) and summer 2015 (n = 60). Significantly higher occurrence of L. pneumophila was observed in summer 2015. Significant differences in temperature for negative and positive samples were not observed, which can be explained by low water temperatures at the point of water consumption. Temperature above 55°C was observed only once, for all other sampling events it ranged from 14°C to 53°C.

Proceedings of the Latvian Academy of Sciences. Section B, Natural, Exact and Applied Sciences, Aug 1, 2016

Ready-to-eat (RTE) foods are challenging for food business operators as they need to remain quali... more Ready-to-eat (RTE) foods are challenging for food business operators as they need to remain qualitative and safe for consumers. However, consumers tend to choose them more and more often because of fast and easy handling. The highest risk from RTE foods is microbiological contamination, particularly for vulnerable groups like children, elderly, and pregnant women. The aim of the research was to assess the microbiological quality of RTE meat and fish products to highlight possible risks for consumers. A total of 15 984 analyses performed on RTE meat and fish products were included in this study. It was found that RTE meat and fish product samples representative of the market in Latvia in the period 2012-2015 had high microbiological quality and only in rare cases was contamination with hygiene indicatororganisms (coliforms and Escherichia coli) and pathogens (Salmonella spp., Listeria monocytogenes, Staphylococcus aureus, and sulphite-reducing clostridia) detected. However, it is important to pay attention to customer habits of cooking and preparing RTE foods as well-thermal processing for products intended to be used cooked, use before expiration date and adequate storage rules for products, as these have important regarding microbiological risks for health.

Parasitology Research, Jul 5, 2018

Acanthamoeba are free-living amoebae found in various ecological environments, and they are major... more Acanthamoeba are free-living amoebae found in various ecological environments, and they are major microbial predators. Some Acanthamoeba species can cause keratitis, granulomatous amoebic encephalitis, and infections of the organs. This is the first study in Latvia describing Acanthamoeba detection by molecular techniques and genotyping using tap water from different sources. An 18S rRNA gene investigation of the 20 Acanthamoeba isolates suggested that 19 belonged to the hazardous T4 genotype and one sample was T12. The results indicate that tap water in Latvia may be a source of Acanthamoeba that is potentially pathogenic to humans. All obtained sequences were submitted to the GenBank database under the following accession numbers: MG386295-MG386314.

Proceedings of the Latvian Academy of Sciences, 2017

International Journal of Environmental Research and Public Health, Dec 22, 2015

Continuous environmental exposure of humans to Legionella may induce immune responses and generat... more Continuous environmental exposure of humans to Legionella may induce immune responses and generation of antibodies. The aim of this study was to investigate the seroprevalence of Legionella pneumophila serogroups (SG) 1-6 in the general healthy population and identify the associated host-related and environmental risk factors. L. pneumophila SG 1-6 seroprevalence among a total of 2007 blood samples collected from healthy donors was 4.8%. Seroprevalence was higher in women (5.9%) than men (3.3%) and in areas with a larger number of inhabitants, ranging from 3.5% in rural regions to 6.8% in the capital, Riga. Blood samples from inhabitants of apartment buildings tested positive for L. pneumophila in more cases (5.8%) compared to those from inhabitants of single-family homes (2.7%). Residents of buildings with a municipal hot water supply system were more likely to be seropositive for L. pneumophila (OR = 3.16, 95% CI 1.26-7.91). Previous episodes of fever were additionally identified as a risk factor (OR = 2.42, 95% CI 1.43-4.1). In conclusion, centralized hot water supply, female gender and previous episodes of fever were determined as the main factors associated with L. pneumophila seropositivity in our study population.

Medicina-lithuania, Aug 15, 2019

Background and Objectives: Legionella is one of the most important water-related pathogens. Insid... more Background and Objectives: Legionella is one of the most important water-related pathogens. Inside the water supply systems and the biofilms, Legionella interact with other bacteria and free-living amoeba (FLA). Several amoebas may serve as hosts for bacteria in aquatic systems. This study aimed to investigate the co-occurrence of Legionella spp. and FLA in drinking water supply systems. Materials and Methods: A total of 268 water samples were collected from apartment buildings, hotels, and public buildings. Detection of Legionella spp. was performed in accordance with ISO 11731:2017 standard. Three different polymerase chain reaction (PCR) protocols were used to identify FLA. Results: Occurrence of Legionella varied from an average of 12.5% in cold water samples with the most frequent occurrence observed in hot water, in areas receiving untreated groundwater, where 54.0% of the samples were Legionella positive. The occurrence of FLA was significantly higher. On average, 77.2% of samples contained at least one genus of FLA and, depending on the type of sample, the occurrence of FLA could reach 95%. In the samples collected during the study, Legionella was always isolated along with FLA, no samples containing Legionella in the absence of FLA were observed. Conclusions: The data obtained in our study can help to focus on the extensive distribution, close interaction, and long-term persistence of Legionella and FLA. Lack of Legionella risk management plans and control procedures may promote further spread of Legionella in water supply systems. In addition, the high incidence of Legionella-related FLA suggests that traditional monitoring methods may not be sufficient for Legionella control.

Pathogens

Legionella is an opportunistic pathogen with a biphasic life cycle that occasionally infects huma... more Legionella is an opportunistic pathogen with a biphasic life cycle that occasionally infects humans. The aim of the study was to assess the distribution of virulence genes and genetic diversity among L. pneumophila isolated from water supply systems of residential buildings in Latvia. In total, 492 water samples from 200 residential buildings were collected. Identification of Legionella spp. was performed according to ISO 11731, and 58 isolates were subjected to whole-genome sequencing. At least one Legionella-positive sample was found in 112 out of 200 apartment buildings (56.0%). The study revealed extensive sequence-type diversity, where 58 L. pneumophila isolates fell into 36 different sequence types. A total of 420 virulence genes were identified, of which 260 genes were found in all sequenced L. pneumophila isolates. The virulence genes enhC, htpB, omp28, and mip were detected in all isolates, suggesting that adhesion, attachment, and entry into host cells are enabled for all ...

Microorganisms

Legionella is one of the most important waterborne pathogens that can lead to both outbreaks and ... more Legionella is one of the most important waterborne pathogens that can lead to both outbreaks and sporadic cases. The majority of travel-associated Legionnaires’ disease (TALD) cases are contracted during hotel stays. The aim of this study was to evaluate the prevalence and genetic diversity of Legionella spp. in hotel water supply systems in Latvia. In total, 834 hot water samples were collected from the water systems of 80 hotels in Latvia. At least one Legionella spp. positive sample was detected in 47 out of 80 hotels (58.8%). Overall, 235 out of 834 samples (28.2%) were Legionella spp. positive. The average hot water temperature in Latvian hotels was 49.8 °C. The most predominant L. pneumophila serogroup (SG) was SG3 which was found in 113 (49.8%) positive samples from 27 hotels. For 79 sequenced L. pneumophila isolates, 21 different sequence types (ST) were obtained, including 3 new types—ST2582, ST2579, and ST2580. High Legionella contamination and high genetic diversity were ...

International Journal of Food Microbiology

Frontiers in Microbiology

Coronary artery disease (CAD) is the most common cardiovascular disease (CVD) and the main leadin... more Coronary artery disease (CAD) is the most common cardiovascular disease (CVD) and the main leading cause of morbidity and mortality worldwide, posing a huge socio-economic burden to the society and health systems. Therefore, timely and precise identification of people at high risk of CAD is urgently required. Most current CAD risk prediction approaches are based on a small number of traditional risk factors (age, sex, diabetes, LDL and HDL cholesterol, smoking, systolic blood pressure) and are incompletely predictive across all patient groups, as CAD is a multi-factorial disease with complex etiology, considered to be driven by both genetic, as well as numerous environmental/lifestyle factors. Diet is one of the modifiable factors for improving lifestyle and disease prevention. However, the current rise in obesity, type 2 diabetes (T2D) and CVD/CAD indicates that the “one-size-fits-all” approach may not be efficient, due to significant variation in inter-individual responses. Recent...

The prevention and control of legionellosis in water supply systems involves environmental compre... more The prevention and control of legionellosis in water supply systems involves environmental comprehensive sampling. Our aim was to investigate occurrence of Legionella spp. in water supply systems in different administrative districts of Riga, and to find out if there exists a correlation between Legionella spp. positive cases and water source, type of sample, sampling point and temperature of hot water, received at the point of consumption. A total 467 samples were collected from 94 apartment buildings in different administrative districts of Riga. Water samples n=302) were taken from heating units in apartment buildings, from taps and shower heads in private apartments and sediment samples were taken in private apartments (n=165). Water temperature was measured during sampling. L.pneumophila was found in 50 out of 94 apartment buildings (53%). From all Legionella spp. positive samples, 19% represented L.pneumophila serogroup 1 and 81% L.pneumophila serogroup 2.-14.(15.). L.pneumoph...

Medicina, 2019

Background and Objectives: Legionella is one of the most important water-related pathogens. Insid... more Background and Objectives: Legionella is one of the most important water-related pathogens. Inside the water supply systems and the biofilms, Legionella interact with other bacteria and free-living amoeba (FLA). Several amoebas may serve as hosts for bacteria in aquatic systems. This study aimed to investigate the co-occurrence of Legionella spp. and FLA in drinking water supply systems. Materials and Methods: A total of 268 water samples were collected from apartment buildings, hotels, and public buildings. Detection of Legionella spp. was performed in accordance with ISO 11731:2017 standard. Three different polymerase chain reaction (PCR) protocols were used to identify FLA. Results: Occurrence of Legionella varied from an average of 12.5% in cold water samples with the most frequent occurrence observed in hot water, in areas receiving untreated groundwater, where 54.0% of the samples were Legionella positive. The occurrence of FLA was significantly higher. On average, 77.2% of sa...

Food Control, 2017

Spices and herbs can contain toxin-producing bacteria and moulds, which can cause health problems... more Spices and herbs can contain toxin-producing bacteria and moulds, which can cause health problems for consumers and contribute to food spoilage and shelf-life reduction. The aims of the present work were (i) to determine the occurence and levels of B. cereus and moulds; (ii) to charactize the incidence and diversity of B. cereus emetic toxin (ces, CER), and diarrhoeal toxin-encoding genes (entFM, nheA, hblC, cytK) and toxigenic potential of Hbl toxin-producing B. cereus strains. Black ground pepper samples showed the most contamination with the highest concentration of B. cereus 2.49 log 10 CFU/g. Moreover, cumin contained the most prominent mould concentration level of 3.6 log 10 CFU/g. The most common moulds were Aspergillus and Penicillium spp. Compared to packaging type, all products acquired from the local market, except curry for B. cereus, exchibited high concentrations of B. cereus and moulds. Four genes were identified e 96% of B. cereus strains contained entFM, 94% nheA, 56% hblC, 42% cytK. None of the samples contained emetic toxin-encoding genes (ces, CER). Toxigenic potential of Hbl toxin was found in 72% of B. cereus strains. Different temperature, moisture levels and hygiene practices were observed at places of sale in local markets thus facilitating contamination and development of moulds. Moreover, the presence of B. cereus and its ability to produce toxins in spices and herbs, may suggest the need to establish microbiological criteria for mould and spore-forming bacteria in spices and herbs.