Quantitative tyramine analysis method for Apis mellifera larvae infected with Melissococcus plutonius, the causative agent of European foulbrood

Tyramine, a trace monoamine produced from tyrosine by decarboxylation and found naturally in foods, plants, and animals, is a suspected virulence factor of Melissococcus plutonius that causes European foulbrood in honey bee brood. In the present study, we developed a method for quantitative analysis of tyramine in culture medium and honey bee larvae with a limit of quantitation of 3 ng/mL and a recovery rate of >97% using Liquid Chromatography-Mass Spectrometry/Mass Spectrometry and deuterium-labeled tyramine, demonstrating for the first time that a highly virulent M. plutonius strain actually produces tyramine in infected larvae. This method will be an indispensable tool to elucidate the role of tyramine in European foulbrood pathogenesis in combination with exposure bioassays using artificially reared bee larvae.

Vagococcus salmoninarum II-qPCR, tropism and egg-associated transmission

Vagococcus salmoninarum was identified as the causative agent of a chronic epizootic in broodstock "coaster" brook trout (Salvelinus fontinalis) at the Iron River National Fish Hatchery. The epizootic spanned more than a year, was unresponsive to multiple florfenicol treatments, and resulted in >50% mortality of the affected fish. The decision was made to cull the remaining fish during spawning, which presented an opportunity to more thoroughly examine V. salmoninarum sampling methods, organ tropism and vertical transmission. A newly developed qPCR targeting the pheS gene was used in concert with bacterial culture to show that V. salmoninarum indeed disproportionately affects females and has a tropism for female reproductive tissues. The study demonstrates that some female reproductive tissues (e.g. ovarian fluid, unfertilized eggs) are also an effective option for non-lethal detection. Despite the widespread presence of V. salmoninarum in ovarian fluid and on egg surfaces, we found no evidence of intra-ova transmission.

Vagococcus salmoninarum I-A chronic coldwater streptococcosis in broodstock brook trout (Salvelinus fontinalis) in Wisconsin, USA

In 2018, Vagococcus salmoninarum was isolated from two lots of broodstock "coaster" brook trout (Salvelinus fontinalis) containing ~1,500 fish at the Iron River National Fish Hatchery, at which time it was identified as the causative agent of a chronic coldwater streptococcosis epizootic. Clinical signs included exophthalmia, lethargy, erratic swimming and loss of equilibrium. Female fish experienced disproportionately higher morbidity and mortality than male co-inhabitants, and routinely retained eggs following spawning. The most consistent gross clinical sign was heart pallor and turbid pericardial effusion. An attempted treatment using florfenicol was ineffective at halting the epizootic, which spanned more than a year and resulted in >50% mortality before remaining fish were culled. As there is no previous documentation of V. salmoninarum at this hatchery or in this species, it is still unclear what circumstances led to this epizootic. The inability to treat this chronic disease led to the loss of valuable broodstock, hampering ongoing fishery conservation efforts in the Great Lakes Basin.

High-throughput identification and quantification of Vagococcus salmoninarum by SYBR Green I-based real-time PCR combined with melting curve analysis

This work describes a primer pair and a high-throughput SYBR Green I-based real-time PCR protocol combined with melting curve analysis for identification and quantification of Vagococcus salmoninarum in bacterial cultures and infected fish tissues. The 16S rRNA gene was selected for the design of the primer pair (SalF and SalR). The sensitivity and specificity of this primer pair were compared with other previously designed for conventional PCR. Although both primer pairs showed 100% specificity using pure bacterial cultures or DNA extracted from bacteria or fish tissues, the primer pairs designed in this study showed the highest sensitivity with a detection limit of 0.034 × 10⁰ amplicon copies per assay (equivalent to 2 × 10^-11  ng/µl, C_q value of 30.49 ± 1.71). The developed qPCR protocol allowed the detection of V. salmoninarum in non-lethal and lethal fish samples with detection levels of 0.17 × 10⁰ gene copies in tissues artificially infected and 0.02 × 10⁰ in tissues of fish experimentally infected with V. salmoninarum. The high sensitivity of the developed method suggests that it could be considered as a useful tool for diagnosis of vagococcosis and the detection of V. salmoninarum in asymptomatic or carrier fish.

Click-conjugated photon-upconversion nanoparticles in an immunoassay for honeybee pathogen Melissococcus plutonius

European foulbrood (EFB) is an infectious disease affecting honeybee larvae caused by the bacterium Melissococcus plutonius. The enzyme-linked immunosorbent assay (ELISA) is the gold standard for antibody-based bacteria detection, however, its sensitivity is not high enough to reveal early-stage EFB infection. Photon-upconversion nanoparticles (UCNPs) are lanthanide-doped nanomaterials that emit light of shorter wavelength under near-infrared (NIR) excitation and thus avoid optical background interference. After conjugation with specific biorecognition molecules, UCNPs can be used as ultrasensitive labels in immunoassays. Here, we introduce a method for conjugation of UCNPs with streptavidin based on copper-free click chemistry, which involves surface modification of UCNPs with alkyne-modified bovine serum albumin (BSA) that prevents the non-specific binding and provides reactive groups for conjugation with streptavidin-azide. To develop a sandwich upconversion-linked immunosorbent assay (ULISA) for M. plutonius detection, we have prepared a rabbit polyclonal anti-Melissococcus antibody. The specific capture of the bacteria was followed by binding of biotinylated antibody and UCNP-BSA-streptavidin conjugate for a highly sensitive upconversion readout. The assay yielded an LOD of 340 CFU mL-1 with a wide working range up to 109 CFU mL-1, which is 400 times better than the LOD of the conventional ELISA. The practical applicability of the ULISA was successfully demonstrated by detecting M. plutonius in spiked real samples of bees, larvae and bottom hive debris. These results show a great potential of the assay for early diagnosis of EFB, which can prevent uncontrolled spreading of the infection and losses of honeybee colonies.

Impact of the particulate matter from wastewater discharge on the abundance of antibiotic resistance genes and facultative pathogenic bacteria in downstream river sediments

Wastewater treatment plants (WWTPs) are point sources for both, the release of antibiotic resistance genes (ARGs) and the discharge of antibiotics (ABs) into the environment. While it is well established that ARGs emission by WWTPs leads to an ARGs increase in receiving rivers, also the role of sub-inhibitory AB concentrations in this context is being discussed. However, the results obtained in this study suggest that, at environmental concentrations, ABs do not have an effect on resistance selection. Instead, we emphasize the significance of ARG transport and, in that respect, highlight the relevance of wastewater particles and associated microorganisms. We can show that ARGs (ermB, bla_TEM,tetM, qnrS) as well as facultative pathogenic bacteria (FPB) (enterococci, Pseudomonas aeruginosa, Acinetobacter baumannii) inside the particulate fraction of WWTP effluent are very likely to remain in the riverbed of the receiving water due to sedimentation. Moreover, ARG and FPB abundances measured in the particulate fraction strongly correlated with the delta ARG and FPB abundances measured in the receiving river sediment (downstream compared to upstream) (R² = 0.93, p < 0.05). Apparently, the sheer amount of settleable ARGs and FPB from WWTP effluent is sufficient, to increase abundances in the receiving riverbed by 0.5 to 2 log units.

Isolation of immune-regulatory Tetragenococcus halophilus from miso

Tetragenococcus halophilus is a halophilic lactic acid bacterium that exists in the traditional Japanese seasoning miso-a fermented soy paste. Considering the popularity of miso as a component of healthy diet, we attempted to evaluate the immunoregulatory functions of T. halophilus spices isolated from miso. We screened 56 strains that facilitated the upregulation of activation markers such as CD86 and CD69 on B cells and T cells in vitro. Of these, 7 strains (Nos. 1, 3, 13, 15, 19, 30, and 31) were found to preferentially induce the CD86 expression on B cells. Furthermore, DNA microarray analysis revealed that T. halophilus strain No. 1 significantly augmented the gene expressions of CD86, CD70, IL-10, INF-γ, and IL-22 in B cells. We confirmed these results at the protein level by flow cytometry. Mice feeding diet containing 1% T. halophilus No. 1 exhibited significantly greater IgA production in the serum. Furthermore, a diet containing 1% T. halophilus No. 1 augmented ovoalbumin (OVA)-specific IgG titer in mice upon OVA/alum immunization. Thus, we demonstrated that T. halophilus No. 1 is a strong immunomodulatory strain with potential as a probiotic.

Investigation of the viral and bacterial microbiota in intestinal samples from mink (Neovison vison) with pre-weaning diarrhea syndrome using next generation sequencing

Pre-weaning diarrhea (PWD) in mink kits is a common multifactorial syndrome on commercial mink farms. Several potential pathogens such as astroviruses, caliciviruses, Escherichia coli and Staphylococcus delphini have been studied, but the etiology of the syndrome seems complex. In pooled samples from 38 diarrheic and 42 non-diarrheic litters, each comprising of intestinal contents from 2-3 mink kits from the same litter, the bacterial populations were studied using Illumina Next Generation Sequencing technology and targeted 16S amplicon sequencing. In addition, we used deep sequencing to determine and compare the viral intestinal content in 31 healthy non-diarrheic and 30 diarrheic pooled samples (2-3 mink kits from the same litter per pool). The results showed high variations in composition of the bacterial species between the pools. Enterococci, staphylococci and streptococci dominated in both diarrheic and non-diarrheic pools. However, enterococci accounted for 70% of the reads in the diarrheic group compared to 50% in the non-diarrheic group and this increase was at the expense of staphylococci and streptococci which together accounted for 45% and 17% of the reads in the non-diarrheic and diarrheic group, respectively. Moreover, in the diarrheic pools there were more reads assigned to Clostridia, Escherichia-Shigella and Enterobacter compared to the non-diarrheic pools. The taxonomically categorized sequences from the virome showed that the most prevalent viruses in all pools were caliciviruses and mamastroviruses (almost exclusively type 10). However, the numbers of reads assigned to caliciviruses were almost 3 times higher in the diarrheic pools compared the non-diarrheic pools and Sapporo-like caliciviruses were more abundant than the Norwalk-like caliciviruses. The results from this study have contributed to the insight into the changes in the intestinal microbiota associated with the PWD syndrome of mink.

Culturable symbionts associated with the reproductive and digestive tissues of the Neotropical brown stinkbug Euschistus heros

Symbionts are widely distributed in eukaryotes, and potentially affect the physiology, ecology and evolution of their host. Most insects harbour free-living bacteria in their haemocoel and gut lumen, intracellular-living bacteria in a range of tissues or bacteria in host-derived specialized cells. Stinkbugs, as do many arthropods, harbour extracellular bacteria in the gut that may affect the fitness of their host. This study identified the culturable symbionts associated with the ovaries, spermatheca, seminal vesicle and posterior midgut region (V4) of males and females of Euschistus heros (F.) (Hemiptera: Pentatomidae). Several culture media were used to isolate the bacteria associated with these structures. The selected colonies (morphotypes) were cultured in liquid medium, subjected to genomic DNA extraction, 16S rRNA gene amplification, and restriction fragment length polymorphism (RFLP) analyses. Morphotypes with distinct RFLP patterns were purified and sequenced, and the sequences obtained were used for putative identification and phylogenetic analysis. Comparison of the sequences with those available in the EzTaxon-e database and the use of a matrix of paired distances grouped the isolates in phylotypes belonging to the Phylum Proteobacteria. Proteobacteria was represented by γ-Proteobacteria phylotypes belonging to Enterobacteriaceae, while Firmicutes had Bacilli phylotypes distributed in Enterococcaceae and Staphylococcaceae. Some of the phylotypes identified were associated exclusively with single structures, such as ovaries, spermatheca and the V4 midgut region of males and females. All culturable bacteria associated with the seminal vesicle were also associated with other tissues.

Segregation of Tetragenococcus halophilus and Zygosaccharomyces rouxii using W1/O/W2 double emulsion for use in mixed culture fermentation

Antagonism in mixed culture fermentation can result in undesirable metabolic activity and negatively affect the fermentation process. Water-oil-water (W₁/O/W₂) double emulsions (DE) could be utilized in fermentation for segregating multiple species and controlling their release and activity. Zygosaccharomyces rouxii and Tetragenococcus halophilus, two predominant microbial species in soy sauce fermentation, were incorporated in the internal W₁ and external W₂ phase of a W₁/O/W₂, respectively. The suitability of DE for controlling T. halophilus and Z. rouxii in soy sauce fermentation was studied in relation to emulsion stability and microbial release profile. The effects of varying concentrations of Z. rouxii cells (5 and 7logCFU/mL) and glucose (0%, 6%, 12%, 30% w/v) in the W₂ phase were investigated. DE stability was determined by monitoring encapsulation stability (%), oil globule size, and microstructure with fluorescence and optical microscopy. Furthermore, the effect of DE on the interaction between T. halophilus and Z. rouxii was studied in Tryptic Soy Broth containing 10% w/v NaCl and 12% w/v glucose and physicochemical changes (glucose, ethanol, lactic acid, and acetic acid) were monitored. DE destabilization resulted in cell release which was proportional to the glucose concentration in W₂. Encapsulated Z. rouxii presented higher survival during storage (~3 log). The application of DE affected microbial cells growth and physiology, which led to the elimination of antagonism. These results demonstrate the potential use of DE as a delivery system of mixed starter cultures in food fermentation, where multiple species are required to act sequentially in a controlled manner.

Vagococcus martis sp. nov., isolated from the small intestine of a marten, Martes flavigula

A novel coccus-shaped, Gram-stain-positive, non-motile and facultative aerobic bacterium, designated strain D7T301T, was isolated from the small intestine of a marten, Martes flavigula, which was killed on the road in Pocheon-si, Gyeonggi-do, Republic of Korea. Grown on a tryptic soy yeast agar plate, colonies had a creamy colour and irregular form. The new isolate formed a monophyletic clade with Vagococcus penaei CD276T on a phylogenetic consensus tree based on the 16S rRNA gene sequence. The isolate grew optimally at 37 °C and pH 7 in the presence of 0.5 % (w/v) NaCl. The isolate was catalase- and oxidase-negative. The cell-wall peptidoglycan was type A4α l-Lys-d-Asp. The major cellular fatty acids were C16 : 0, C14 : 0, and C16 : 1ω9c. The predominant respiratory quinone was menaquinone MK-7 (85.1 %). The DNA G+C content based on genome sequencing was 33.8 mol%. The average nucleotide identity value obtained from comparative genomic analysis between strain D7T301T and V. penaei CIP 109914T was 72.6 %. On the basis of the phenotypic, phylogenetic, biochemical, chemotaxonomic, and genotypic analyses, Vagococcusmartis is proposed as a novel species of the genus Vagococcus. The type strain is D7T301T (=KCTC 21069T=JCM 31178T).

Vagococcus humatus sp. nov., isolated from soil beneath a decomposing pig carcass

A Gram-stain-positive, non-motile, coccus-shaped bacterium, designated strain C25T, was isolated from the soil beneath a decomposing pig carcass in Korea and was characterized using a polyphasic taxonomic approach. Comparative 16S rRNA gene sequence analysis showed that strain C25T belongs to the genus Vagococcus in the family Enterococcaceae of the Lactobacillales. 16S rRNA gene sequence analysis showed that strain C25T was closely related to Vagococcus lutrae CCUG 39187T (96.5 % similarity) and Enterococcus termitis LMG 8895T (95.8 %). The chemotaxonomic properties of strain C25T were consistent with those of the genus Vagococcus; the major cellular fatty acids consisted of C16 : 0, C16 : 1ω9c and C18 : 1ω9c, and the cell-wall peptidoglycan type was based on meso-diaminopimelic acid. The G+C content of the genomic DNA was 44 mol%. On the basis of phylogenetic inference, fatty acid profile, and chemotaxonomic and other phenotypic properties, strain C25T is clearly differentiated from closely related type strains of the genus Vagococcus and represents a novel species in this genus, for which the name Vagococcus humatus sp. nov. is proposed. The type strain is C25T (=KEMB 562-002T=JCM 31581T).

Next-Generation Sequencing Analyses of Bacterial Community Structures in Soybean Pastes Produced in Northeast China

Fermented soybean foods contain nutritional components including easily digestible peptides, cholesterol-free oils, minerals, and vitamins. Various fermented soybean foods have been developed and are consumed as flavoring condiments in Asian regions. While the quality of fermented soybean foods is largely affected by microorganisms that participate in the fermentation process, our knowledge about the microorganisms in soybean pastes manufactured in Northeast China is limited. The current study used a culture-independent barcoded pyrosequencing method targeting hypervariable V1/V2 regions of the 16S rRNA gene to evaluate Korean doenjang and soybean pastes prepared by the Hun Chinese (SPHC) and Korean minority (SPKM) populations in Northeast China. In total, 63399 high-quality sequences were derived from 16 soybean paste samples collected in Northeast China. Each bacterial species-level taxon of SPHC, SPKM, and Korean doenjang was clustered separately. Each paste contained representative bacterial species that could be distinguished from each other: Bacillus subtilis in SPKM, Tetragenococcus halophilus in SPHC, and Enterococcus durans in Korean doenjang. This is the 1st massive sequencing-based study analyzing microbial communities in soybean pastes manufactured in Northeast China, compared to Korean doenjang. Our results clearly showed that each soybean paste contained unique microbial communities that varied depending on the manufacturing process and location.

Safety assessment of Tetragenococcus halophilus isolates from doenjang, a Korean high-salt-fermented soybean paste

We assessed the safety of 49 Tetragenococcus halophilus strains isolated from doenjang in Korea. Minimum inhibitory concentration assays showed that all strains can be considered as susceptible to ampicillin, erythromycin, penicillin G, tetracycline, and vancomycin, but resistant to ciprofloxacin based on the Enterococcus breakpoint values provided by the European Committee on Antimicrobial Susceptibility testing in 2015. Ciprofloxacin resistance was sufficiently high to consider the potential for acquisition of transmissible determinants. Two strains exhibiting potentially acquired resistance to chloramphenicol and gentamicin, and chloramphenicol alone, were identified. None of the strains exhibited α-hemolytic activity or biofilm formation; two strains exhibited weak β-hemolytic activity. Doenjang isolates produced an average of 3338.6 ppm of tyramine in the laboratory, considerably higher than the levels produced by two reference strains. All of the test strains exhibited similar cadaverine, histamine, and putrescine production patterns. Most T. halophilus strains could grow at a NaCl concentration >18%, exhibited acid production at 15% NaCl, and expressed strain-specific protease and lipase activities. The potential acquisition of transmissible determinants for antibiotic resistance and tyramine production identified in this study necessitate the need for a thorough safety assessment of T. halophilus before it can be considered for use in food fermentation processes.

Bacterial communities associated with invasive populations of Bactrocera dorsalis (Diptera: Tephritidae) in China

The oriental fruit fly Bactrocera dorsalis (Hendel) is a destructive insect pest of a wide range of fruits and vegetables. This pest is an invasive species and is currently distributed in some provinces of China. To recover the symbiotic bacteria of B. dorsalis from different invasion regions in China, we researched the bacterial diversity of this fruit fly among one laboratory colony (Guangdong, China) and 15 wild populations (14 sites in China and one site in Thailand) using DNA-based approaches. The construction of 16S rRNA gene libraries allowed the identification of 24 operational taxonomic units of associated bacteria at the 3% distance level, and these were affiliated with 3 phyla, 5 families, and 13 genera. The higher bacterial diversity was recovered in wild populations compared with the laboratory colony and in samples from early term invasion regions compared with samples from late term invasion regions. Moreover, Klebsiella pneumoniae and Providencia sp. were two of the most frequently recovered bacteria, present in flies collected from three different regions in China where B. dorsalis is invasive. This study for the first time provides a systemic investigation of the symbiotic bacteria of B. dorsalis from different invasion regions in China.

Rainfall-induced release of microbes from manure: model development, parameter estimation, and uncertainty evaluation on small plots

A series of simulated rainfall-runoff experiments with applications of different manure types (cattle solid pats, poultry dry litter, swine slurry) was conducted across four seasons on a field containing 36 plots (0.75 × 2 m each), resulting in 144 rainfall-runoff events. Simulating time-varying release of Escherichia coli, enterococci, and fecal coliforms from manures applied at typical agronomic rates evaluated the efficacy of the Bradford-Schijven model modified by adding terms for release efficiency and transportation loss. Two complementary, parallel approaches were used to calibrate the model and estimate microbial release parameters. The first was a four-step sequential procedure using the inverse model PEST, which provides appropriate initial parameter values. The second utilized a PEST/bootstrap procedure to estimate average parameters across plots, manure age, and microbe, and to provide parameter distributions. The experiment determined that manure age, microbe, and season had no clear relationship to the release curve. Cattle solid pats released microbes at a different, slower rate than did poultry dry litter or swine slurry, which had very similar release patterns. These findings were consistent with other published results for both bench- and field-scale, suggesting the modified Bradford-Schijven model can be applied to microbial release from manure.

Fate and transport of enteric microbes from septic systems in a coastal watershed

Onsite wastewater treatment systems (OWTS) are commonly used in coastal areas to treat household wastewater. These systems represent potential sources of fecal pollution of groundwater and nearby surface water. OWTS are expected to reduce microbial concentrations in wastewater; however, system and environmental factors can affect treatment efficiency and impacts on ground and surface water. In the study of OWTS described in this article, the authors sampled septic tanks and groundwater at two households in coastal North Carolina between October 2009 and October 2011. Samples were tested for the fecal indicator microbes E. coli, enterococci, and Clostridium perfringens. Microbial source tracking was also performed in year two. Results showed that enteric microbe concentrations in groundwater significantly decreased with distance from the OWTS. Human markers of fecal contamination were also detected in the OWTS and downgradient groundwater, indicating that OWTS can impact the microbial quality of shallow groundwater.

Long-term monitoring of molecular markers can distinguish different seasonal patterns of fecal indicating bacteria sources

Elevated levels of fecal indicator bacteria (FIB) have been observed at Topanga Beach, CA, USA. To identify the FIB sources, a microbial source tracking study using a dog-, a gull- and two human-associated molecular markers was conducted at 10 sites over 21 months. Historical data suggest that episodic discharge from the lagoon at the mouth of Topanga Creek is the main source of bacteria to the beach. A decline in creek FIB/markers downstream from upper watershed development and a sharp increase in FIB/markers at the lagoon sites suggest sources are local to the lagoon. At the lagoon and beach, human markers are detected sporadically, dog marker peaks in abundance mid-winter, and gull marker is chronically elevated. Varied seasonal patterns of FIB and source markers were identified showing the importance of applying a suite of markers over long-term spatial and temporal sampling to identify a complex combination of sources of contamination.

Isolation and characterization of Vagococcus sp from midgut of Culex quinquefasciatus (Say) mosquito

BACKGROUND & OBJECTIVES

Mosquito gut is a rich source of microorganisms. These microorganisms exhibit close association and contribute various physiological processes taking place in mosquito gut. The present study is aimed to characterize two bacterial isolates M19 and GB11 recovered from the gut of Culex quinquefasciatus mosquito collected from Bhuj and Jamnagar districts of Gujarat, India.

METHODS

Both the strains were characterized using polyphasic approach including, phenotypic characterization, whole cell protein profiling and sequencing of 16S rRNA gene and groESL region.

RESULTS

Sequences of 16S rRNA gene of M19 and GB11 were 99% similar to Vagococcus carniphilus and Vagococcus fluvialis. But phenotypic profile, whole cell protein profile and sequence of groESL region of both isolates were found to be similar to V. fluvialis.

CONCLUSION

Based on phenotypic, genotypic and protein profiling, both the strains were identified as V. fluvialis. So far this species was known from domestic animals and human sources only. This is the first report of V. fluvialis inhabiting midgut of Cx. quinquefasciatus mosquito collected from Arabian sea coastal of India.

Winter survival of microbial contaminants in soil: an in situ verification

The aim of the research was to evaluate, at site scale, the influence of freezing and freeze/thaw cycles on the survival of faecal coliforms and faecal enterococci in soil, in a climate change perspective. Before the winter period and during grazing, viable cells of faecal coliforms and faecal enterococci were detected only in the first 10 cm below ground, while, after the winter period and before the new seasonal grazing, a lower number of viable cells of both faecal indicators was detected only in some of the investigated soil profiles, and within the first 5 cm. Taking into consideration the results of specific investigations, we hypothesise that the non-uniform spatial distribution of grass roots within the studied soil can play an important role in influencing this phenomenon, while several abiotic factors do not play any significant role. Taking into account the local trend in the increase of air temperature, a different distribution of microbial pollution over time is expected in spring waters, in future climate scenarios. The progressive increase in air temperature will cause a progressive decrease in freeze/thaw cycles at higher altitudes, minimising cold shocks on microbial cells, and causing spring water pollution also during winter.

Molecular epidemiology and population structure of the honey bee brood pathogen Melissococcus plutonius

Melissococcus plutonius is the causative agent of European foulbrood (EFB), which is a serious brood disease of the European honey bee (Apis mellifera). EFB remains a threat because of a poor understanding of disease epidemiology. We used a recently published multi-locus sequence typing method to characterise 206 M. plutonius isolates recovered from outbreaks in England and Wales over the course of 2 years. We detected 15 different sequence types (STs), which were resolved by eBURST and phylogenetic analysis into three clonal complexes (CCs) 3, 12 and 13. Single and double locus variants within CC3 were the most abundant and widespread genotypes, accounting for 85% of the cases. In contrast, CCs 12 and 13 were rarer and predominantly found in geographical regions of high sampling intensity, consistent with a more recent introduction and localised spread. K-function analysis and interpoint distance tests revealed significant geographical clustering in five common STs, but pointed to different dispersal patterns between STs. We noted that CCs appeared to vary in pathogenicity and that infection caused by the more pathogenic variants is more likely to lead to honey bee colony destruction, as opposed to treatment. The importance of these findings for improving our understanding of disease aetiology and control are discussed.

The effect of experimental fusarium mycotoxicosis on microbiota diversity in porcine ascending colon contents

The objective of the study was to determine the effect of exposure of pigs to the Fusarium mycotoxins zearalenone (ZEN) and deoxynivalenol (DON), administered together and separately, on the colon microbiota. An experiment was conducted for 42 days on gilts, randomly assigned to four groups and administered either ZEN, DON, ZEN+DON, or a placebo. The number of aerobic mesophilic bacteria, yeasts, molds, anaerobic Clostridium perfringens, fecal streptococci, Enterobacteriaceae, Escherichia coli, and lactic acid bacteria (LAB) were determined in the contents of the ascending colon. The influence of mycotoxins on the functional diversity of the colonic microbiota was assessed using EcoPlate tests (Biolog). Analysis revealed the predominance of LAB in all groups of pigs. Zearalenone, administered separately and together with DON, was found to have an adverse effect on mesophilic aerobic bacteria, but only after long exposure to this mycotoxin. During the six weeks of the experiment, the concentration of C. perfringens, E. coli, and other bacteria in the family Enterobacteriaceae was most considerably reduced in the experimental groups exposed to zearalenone, both separately and together with DON. Mycotoxins also affected the functional biodiversity of microorganisms. Both Shannon’s diversity index and the number of catabolized substrates in Biolog plate (the R index) were much higher in the group subjected to mixed mycotoxicosis.

Recent molecular biology methods for foulbrood and nosemosis diagnosis

Honey-bee colony losses are an increasing problem in Western countries. There are many different causes, including infections due to various pathogens. Molecular biology techniques have been developed to reliably detect and identify honey-bee pathogens. The most sensitive, specific and reliable is the quantitative real-time polymerase chain reaction (qPCR) methodology. This review of the literature describes various studies where qPCR was used to detect, identify and quantify four major honey-bee pathogens: the bacteria Paenibacillus larvae and Melissococcus plutonius (the causative agents of American foulbrood and European foulbrood, respectively) and the microsporidia Nosema apis and N. ceranae (the causative agents of nosemosis). The application of qPCR to honey-bee pathogens is very recent, and techniques are expected to improve rapidly, leading to potential new prospects for diagnosis and control. Thus, qPCR techniques could shortly become a powerful tool for investigating pathogenic infections and increasing our understanding of colony losses.

Typing of Melissococcus plutonius isolated from European and Japanese honeybees suggests spread of sequence types across borders and between different Apis species

Melissococcus plutonius is an important pathogen of honeybee larvae and causes European foulbrood (EFB) not only in European honeybees (Apis mellifera) but also in other native honeybees. We recently confirmed the first EFB case in Japanese native honeybees (Apis cerana japonica) and isolated M. plutonius from this case. In this study, to obtain a better understanding of the ecology of M. plutonius and the epidemiology of EFB, we analyzed M. plutonius isolates that originated from European and Japanese honeybees in Japan using an existing multilocus sequence typing scheme. These analyzed Japanese isolates were resolved into six sequence types (STs), three of which were novel STs. Among these six STs, ST3 and ST12 were the two most common and found in isolates from both European and Japanese honeybees (or their environment). Moreover, these two STs were identified not only in Japan but also in other countries, suggesting the spread of some STs across borders and different honeybee species.

Multi-laboratory evaluations of the performance of Catellicoccus marimammalium PCR assays developed to target gull fecal sources

Here we report results from a multi-laboratory (n = 11) evaluation of four different PCR methods targeting the 16S rRNA gene of Catellicoccus marimammalium originally developed to detect gull fecal contamination in coastal environments. The methods included a conventional end-point PCR method, a SYBR(®) Green qPCR method, and two TaqMan(®) qPCR methods. Different techniques for data normalization and analysis were tested. Data analysis methods had a pronounced impact on assay sensitivity and specificity calculations. Across-laboratory standardization of metrics including the lower limit of quantification (LLOQ), target detected but not quantifiable (DNQ), and target not detected (ND) significantly improved results compared to results submitted by individual laboratories prior to definition standardization. The unit of measure used for data normalization also had a pronounced effect on measured assay performance. Data normalization to DNA mass improved quantitative method performance as compared to enterococcus normalization. The MST methods tested here were originally designed for gulls but were found in this study to also detect feces from other birds, particularly feces composited from pigeons. Sequencing efforts showed that some pigeon feces from California contained sequences similar to C. marimammalium found in gull feces. These data suggest that the prevalence, geographic scope, and ecology of C. marimammalium in host birds other than gulls require further investigation. This study represents an important first step in the multi-laboratory assessment of these methods and highlights the need to broaden and standardize additional evaluations, including environmentally relevant target concentrations in ambient waters from diverse geographic regions.

A typing scheme for the honeybee pathogen Melissococcus plutonius allows detection of disease transmission events and a study of the distribution of variants

Melissococcus plutonius is the bacterial pathogen that causes European Foulbrood of honeybees, a globally important honeybee brood disease. We have used next-generation sequencing to identify highly polymorphic regions in an otherwise genetically homogenous organism, and used these loci to create a modified MLST scheme. This synthesis of a proven typing scheme format with next-generation sequencing combines reliability and low costs with insights only available from high-throughput sequencing technologies. Using this scheme we show that the global distribution of M.plutonius variants is not uniform. We use the scheme in epidemiological studies to trace movements of infective material around England, insights that would have been impossible to confirm without the typing scheme. We also demonstrate the persistence of local variants over time.

Development and application of a quantitative PCR assay targeting Catellicoccus marimammalium for assessing gull-associated fecal contamination at Lake Erie beaches

Gulls represent one of the major fecal contamination sources responsible for the degradation of water quality at Lake Erie beaches. For assessing gull-associated fecal contamination, a real-time quantitative PCR assay (qPCR) targeting 16S rRNA gene sequences from Catellicoccus marimammalium, which are abundant in gull feces, was developed and evaluated by comparing assay results with beach survey data that included gull counting, and quantifying densities of Escherichia coli and human-associated fecal markers at two Lake Erie beaches. In evaluating the specificity and sensitivity of the qPCR assay with animal and wastewater samples, C. marimammalium was detected in most gull fecal samples (80.7%), some chicken fecal samples (24.1%), but was not readily detected from other fecal samples of animals and humans, and wastewater. Among 66 Lake Erie water samples collected in 2010, C. marimammalium was frequently detected from Villa Angela (36.4%) and Headlands beaches (57.6%). C. marimammalium densities were not associated with E. coli densities or sanitary survey data. E. coli counts were likely driven by other sources, such as human, rather than gulls at the study sites. The presumption that human contamination influenced E. coli counts was supported by more frequent detection of the human-specific Bacteroides gyrB marker (gyrB) at Villa Angela (33.3%) than Headlands (6.1%). Since E. coli may not be an effective indicator for assessing gull-related fecal contamination at these beaches, where contamination sources are mixed, our novel qPCR assay can be useful for understanding fecal source contributions from gulls not explained by gull abundance or E. coli densities.

Water quality assessment of a Central European River - does the Directive 2000/60/EC cover all the needs for a comprehensive classification?

Over the last decades, European rivers have mostly shared the same fate. Until the mid 1980s many of them were in rather bad shape. Nobody would have thought about using the waters for recreation. However, continuous efforts over the last three decades have achieved success and today's water quality has changed to the better. This obvious change in water quality, which was proved by investigations done on the basis of the European Directive 2000/60/EC framework for Community action in the field of water policy, made people consider using the rivers for recreation or irrigation. In the present study a Central European River was investigated from hygienic perspectives (faecal indicators), and its toxicological status was examined - both of which are parameters which are not included in the Directive 2000/60/EC. The pivotal question was whether these parameters provide essential and additional information about the river's status and its quality. In general, the monthly values for all sampling points from the toxicological tests correlated with the determined physical and chemical statuses according to the national water management plan. Once, however, the toxicological values did increase significantly. This detection of a single toxicological burst within a year of observation underlines the applicability of the tests as screening methods for the detection of toxic substances. Moreover, our microbiological investigations show high numbers of faecal indicators and Salmonellae. These results are not consistent with the apparently good quality of the river. Therefore faecal indicators, which are directly related to the discharge of waste water, should be an integral part of the procedure of water classification.

[In vitro activity of linezolid and dalbavancin against vancomycin-resistant enterococci]

The incidence of infections caused by multidrug resistant gram-positive bacteria is increasing worlwide. In addition, emergence and dissemination of glycopeptide resistance in enterococci has accelerated the need for the development of new antimicrobial agents for treatment. Linezolid which is an oxazolidinone and dalbavancin which is a second-generation, semi-synthetic lipoglycopeptid are important therapeutic options for infections caused by antimicrobial-resistant gram-positive pathogens. The aim of this study was to investigate the in-vitro antimicrobial activity of linezolid and dalbavancin against vancomycin- resistant enterococci (VRE). A total of 100 VRE strains, isolated from rectal swabs of patients hospitalized in Istanbul University Faculty of Istanbul Medicine between 2006-2007 were included in the study. All strains were identified as Enterococcus spp. by conventional methods and had minimum inhibitory concentrations (MICs) of ≥ 32 µg/ml for vancomycin. Vancomycin, linezolid and dalbavancin susceptibility testing was performed by broth microdilution method. For the quality control of the tests, S.aureus ATCC 29213 and E.faecalis ATCC 29212 were included in each run. Molecular identification of linezolid-resistant strains (n= 2) were done by 16S rRNA sequencing and resistance mechanisms were tested by 23S rRNA sequencing. Against VRE strains, MIC50, MIC90 and MIC ranges of linezolid and dalbavancin were found as 4, 4, 1-16 µg/ml and 32, 64, 0.25-128 µg/ml, respectively. Linezolid susceptibility, intermediate susceptibility and resistance rates were found as 32%, 66% and 2% in the same order. Linezolid-resistant two strains were identified as E.faecium, and this data was confirmed by Pasteur Institute. Both of those isolates had G2576T mutations in 23S rRNA genes. Because susceptibility breakpoint for dalbavancin has not been established by Clinical and Laboratory Standards Institute (CLSI) yet, susceptibility and resistance rates for dalbavancin were not indicated. According to the MIC results, linezolid was found to be the most effective antibiotic against VRE strains, and dalbavancin was found more effective than vancomycin. Additionally, our results showed that routine susceptibility testing of VRE strains isolated from hospitalized patients to linezolid was required.

[Intestine microbiocenosis in mechanical jaundice caused by obturation of biliary ducts]

AIM

Study the composition of bile and feces microflora in patients with mechanical jaundice of various geneses.

MATERIALS AND METHODS

66 feces and 25 bile samples during nasobiliary decompression were studied bacteriologically.

RESULTS

In all patients disorders of normal intestine microflora were detected. Patient bile in 84% of cases was infected by bacteria among which enterococci and urease positive enterobacteria predominated. In 30% of cases in patients identical species of bacteria were simultaneously detected in bile samples and in high titers (6.0 - 6.5 lg CFU/ml) in feces.

CONCLUSION

In mechanical jaundice caused by biliary duct obturation in all the patients dysbiotic events of digestive tract are registered, that defines the necessity to improve bacteriological examination of patients with mechanical jaundice and reasonability of disrupted normal intestine microflora correction.

Diversity of Melissococcus plutonius from honeybee larvae in Japan and experimental reproduction of European foulbrood with cultured atypical isolates

European foulbrood (EFB) is an important infectious disease of honeybee larvae, but its pathogenic mechanisms are still poorly understood. The causative agent, Melissococcus plutonius, is a fastidious organism, and microaerophilic to anaerobic conditions and the addition of potassium phosphate to culture media are required for growth. Although M. plutonius is believed to be remarkably homologous, in addition to M. plutonius isolates with typical cultural characteristics, M. plutonius-like organisms, with characteristics seemingly different from those of typical M. plutonius, have often been isolated from diseased larvae with clinical signs of EFB in Japan. Cultural and biochemical characterization of 14 M. plutonius and 19 M. plutonius-like strain/isolates revealed that, unlike typical M. plutonius strain/isolates, M. plutonius-like isolates were not fastidious, and the addition of potassium phosphate was not required for normal growth. Moreover, only M. plutonius-like isolates, but not typical M. plutonius strain/isolates, grew anaerobically on sodium phosphate-supplemented medium and aerobically on some potassium salt-supplemented media, were positive for β-glucosidase activity, hydrolyzed esculin, and produced acid from L-arabinose, D-cellobiose, and salicin. Despite the phenotypic differences, 16S rRNA gene sequence analysis and DNA-DNA hybridization demonstrated that M. plutonius-like organisms were taxonomically identical to M. plutonius. However, by pulsed-field gel electrophoresis analysis, these typical and atypical (M. plutonius-like) isolates were separately grouped into two genetically distinct clusters. Although M. plutonius is known to lose virulence quickly when cultured artificially, experimental infection of representative isolates showed that atypical M. plutonius maintained the ability to cause EFB in honeybee larvae even after cultured in vitro in laboratory media. Because the rapid decrease of virulence in cultured M. plutonius was a major impediment to elucidation of the pathogenesis of EFB, atypical M. plutonius discovered in this study will be a breakthrough in EFB research.

Occurrence, molecular characterization and antibiogram of water quality indicator bacteria in river water serving a water treatment plant

Water pollution by microorganisms of fecal origin is a current world-wide public health concern. Total coliforms, fecal coliforms (Escherichia coli) and enterococci are indicators commonly used to assess the microbiological safety of water resources. In this study, influent water samples and treated water were collected seasonally from a water treatment plant and two major water wells in a Black Belt county of Alabama and evaluated for water quality indicator bacteria. Influent river water samples serving the treatment plant were positive for total coliforms, fecal coliforms (E. coli), and enterococci. The highest number of total coliform most probable number (MPN) was observed in the winter (847.5 MPN/100 mL) and the lowest number in the summer (385.6 MPN/100 mL). Similarly E. coli MPN was substantially higher in the winter (62.25 MPN/100 mL). Seasonal variation of E. coli MPN in influent river water samples was strongly correlated with color (R(2)=0.998) and turbidity (R(2)=0.992). Neither E. coli nor other coliform type bacteria were detected in effluent potable water from the treatment plant. The MPN of enterococci was the highest in the fall and the lowest in the winter. Approximately 99.7 and 51.5 enterococci MPN/100 mL were recorded in fall and winter seasons respectively. One-way ANOVA tests revealed significant differences in seasonal variation of total coliforms (P<0.05), fecal coliforms (P<0.01) and enterococci (P<0.01). Treated effluent river water samples and well water samples revealed no enterococci contamination. Representative coliform bacteria selected by differential screening on Coliscan Easygel were identified by 16S ribosomal RNA gene sequence analysis. E. coli isolates were sensitive to gentamicin, trimethoprim/sulfamethazole, ciprofloxacin, vancomycin, tetracycline, ampicillin, cefixime, and nitrofurantoin. Nonetheless, isolate BO-54 displayed decreased sensitivity compared to other E. coli isolates. Antibiotic sensitivity pattern can be employed in microbial source tracking.

Use of Tetragenococcus halophilus as a starter culture for flavor improvement in fish sauce fermentation

The potential of Tetragenococcus halophilus as a starter culture for flavor improvement in fish sauce fermentation was elucidated. Four strains of T. halophilus isolated from fish sauce mashes were inoculated to anchovy mixed with 25% NaCl with an approximate cell count of 10(6) CFU/mL. The α-amino content of 6-month-old fish sauce samples inoculated with T. halophilus was 780-784 mM. The addition of T. halophilus MRC10-1-3 and T. halophilus MCD10-5-10 resulted in a reduction of histamine (P < 0.05). Fish sauce inoculated with T. halophilus showed high contents of total amino acids with predominantly high glutamic acid. Major volatile compounds in fish sauce were 2-methylpropanal, 2-methylbutanal, 3-methylbutanal, and benzaldehyde. T. halophilus-inoculated fish sauce samples demonstrated the ability to reduce dimethyl disulfide, a compound contributing to a fecal note. The use of T. halophilus for fish sauce fermentation improves amino acid profiles and volatile compounds as well as reduces biogenic amine content of a fish sauce product.

[Colonization of the teat skin and the teat canal of lactating dairy cattle by mastitis pathogens]

OBJECTIVE

The teat canal of lactating dairy cattle is the first barrier against mastitis pathogens invading the teat cistern and the udder lumen. However, in several studies it could be shown that the teat skin and the teat canal epithelium are colonized by mainly staphylococci as well as by other pathogenic or facultative pathogenic micro-organisms. The aim of the study was to evaluate the pathogen pressure on the bovine mammary gland and to establish data on the prevalence of relevant micro-organisms.

MATERIAL AND METHODS

In 32 randomly selected German dairy farms the colonization of the teat skin and the teat canal by S.aureus (Baird Parker agar), Sc.uberis (modified Rambach agar according to Watts et al. [1993]), enterococci (kanamycin esculin azide agar) and coliforms (ChromoCult Coliform agar) was investigated by the wet/dry swab technique DIN10113-1:1997-07.

RESULTS

In total 84.5% of all 1358 investigated teat canals of clinically healthy cattle were colonized by at least one of the four pathogen groups. S.aureus was isolated from 72.2% of the teat canals. For S.aureus , Sc.uberis and E.coli maximum bacterial counts of >10(6) cfu/swab and for other coliform bacteria>10(7) cfu/swab were detected. Correlations could be found between the bacterial counts on the teat skin and in the teat canal within the pathogen groups S.aureus, Sc.uberis, E.coli and other coliforms (Spearman's rank correlation coefficient r≥0.30, p<0.001) as well as between the environmental udder pathogens Sc.uberis and coliforms (r≥0.25, p<0.01).

CONCLUSION AND CLINICAL RELEVANCE

The variation of the bacterial counts on teat epithelia could be an indicator that the microflora of the teat canal epithelium can be affected by management practices in dairy farms. The results of this study point out that under field conditions the efficiency of hygienic practices (husbandry, milking) can be assessed by sampling of the bovine teat canal by the wet/dry swab technique.

Comparison of PCR-DGGE and PCR-SSCP analysis for bacterial flora of Japanese traditional fermented fish products, aji-narezushi and iwashi-nukazuke

BACKGROUND

The bacterial flora of two Japanese traditional fermented fish products, aji-narezushi (salted and long-fermented horse mackerel (Trachurus japonicas) with rice) and iwashi-nukazuke (salted and long-fermented sardine (Sardinops melanostica) with rice bran), was analysed using non-culture-based polymerase chain reaction (PCR) denaturing gradient gel electrophoresis (DGGE) and culture-based PCR single-strand conformation polymorphism (SSCP) methods.

RESULTS

Viable plate counts in aji-narezushi and iwashi-nukazuke were about 6.3-6.6 and 5.7-6.9 log colony-forming units g(-1) respectively. In the PCR-DGGE analysis, Lactobacillus acidipiscis was detected as the predominant bacterium in two of three aji-narezushi samples, while Lactobacillus versmoldensis was predominant in the third sample. By the PCR-SSCP method, Lb. acidipiscis and Lactobacillus plantarum were isolated as the predominant bacteria, while Lb. versmoldensis was not detected. The predominant bacterium in two of three iwashi-nukazuke samples was Tetragenococcus muriaticus, while Tetragenococcus halophilus was predominant in the third sample.

CONCLUSION

The results suggest that the detection of some predominant lactic acid bacteria species in fermented fish by cultivation methods is difficult.

Rapid dead-end ultrafiltration concentration and biosensor detection of enterococci from beach waters of Southern California

Same-day microbial water quality assessments are not possible with standard methods, which increases the possibility of public exposure to fecal pathogens. This study examined the efficacy of high-volume hollow fibre ultrafiltration coupled to biosensor detection for enterococci in marine waters to allow same-day public notification of poor water quality. Fifty-six 1001 ultrafiltered samples and 100 ml grab samples were collected weekly from May to July 2007. Post-ultrafiltration processing included sonication and micron sieve passage to remove interfering particulates, followed by centrifugation for secondary concentration. Levels of enterococci in grab and ultrafiltration samples were determined by a standard method (EPA method 1600) for calculation of recovery efficiencies and concentration factors. Each final retentate was analysed with the RAPTOR evanescent wave biosensor. Enterococci levels increased over 26,000-fold in final retentates. Enterococci were detected when ambient concentrations exceeded the regulatory standard for a single sample (> or = 105 CFU/100 ml), and detection was highly correlated with breaches of the single-sample regulatory limit. The combined procedure required 2.5 h for detection compared with 24h for EPA method 1600. This field study achieved rapid detection of enterococci by ultrafiltration, secondary concentration and biosensor analysis, and demonstrates its potential usefulness for water quality monitoring.