Sensitive immunoassay of Legionella using multivalent conjugates of engineered VHHs.

VHH antibodies or nanobodies, which are antigen-binding domains of heavy chain antibodies from camelid species, have several advantageous characteristics, including compact molecular size, high productibility in bacteria and easy engineering for functional improvement. Focusing on these advantages of VHHs, we attempted to establish an immunoassay system for detection of Legionella, the causative pathogen of Legionnaires' disease. A VHH phage display library was constructed using cDNA from B cells of alpacas immunized with Legionella pneumophila serogroup1 (LpSG1). Through biopanning, two specific VHH clones were isolated and used to construct a Legionella detection system based on the latex agglutination assay. After engineering the VHHs and improving the assay system, the sensitive detection system was successfully established for the LpSG1 antigen. The immunoassay developed in this study should be useful in easy and sensitive detection of Legionella, the causative agent of Legionnaires' disease, which is a potentially fatal pneumonia.

Evaluation of Serotyping of Environmental and Clinical Isolates of Legionella pneumophila using MALDI-TOF MS.

Legionella pneumophila (L. pneumophila) is responsible for most Legionnaire's disease cases diagnosed worldwide. The species includes 16 serogroups, but most Legionnaire's disease cases (85.7% in Europe, 87.0% in Japan) are caused by L. pneumophila serogroup 1. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) can be used to identify the L. pneumophila serogroup. In this study, we compared three sample preparation methods that are compatible with MALDI-TOF MS: the direct colony transfer method (DCTM), on-target extraction method (OTEM), and in-tube extraction method (ITEM). The aim was to improve the low identification rates for L. pneumophila, and establish and validate a simple, rapid and robust MALDI-TOF MS-based method for routine use in microbiological laboratories for assignment of L. pneumophila isolates to serogroups and identification of reliable peak biomarkers. Using ITEM, 100.0% (29/29) of hot spring water samples and clinical isolates were correctly identified at the species level. Augmented reference spectra correctly identified all 29 strains at the species level and 29 isolates at the serogroup level, displaying sensitivity, specificity and accuracy of 100.0% for serogroup assignment. MALDI-TOF MS is a relatively inexpensive method for assignment of L. pneumophila serogroups that can serve as a first-line tool for rapid prospective typing.

[Behavior of Staphylococcus aureus and Staphylococcal Enterotoxins A and Q in Scrambled Eggs].

Staphylococcal food poisoning (SFP) is caused by Staphylococcus aureus, and its typical symptom of vomiting is evoked by staphylococcal enterotoxins (SEs). SEs are classified as classical and new types. SEQ is a new-type enterotoxin predicted to have a high potential risk for SFP. To elucidate the correlation between the number of S. aureus cells and the production of SEs as well as classical and new-type enterotoxins in the food environment, the numbers of S. aureus strain cells carrying sea and seq genes and the production of SEA and SEQ protein were examined under 3 pHs values (pH 6.0, 7.0 and 8.0) and 2 NaCl concentrations (0.5 and 1.0%) conditions. The experiments were performed at 25℃, resembling the setting of scrambled eggs at room temperature after cooking. By 24 hr after incubation, the cell number in the scrambled egg was ≥107/10 g, reaching 109/10 g by 48 hr under all conditions. The productions of both SEA and SEQ were detected in the scrambled egg under all conditions by 48 h. SEQ was detected from 24 hr at all 3 pH values in the egg containing 1.0% NaCl, whereas in the egg containing 0.5% NaCl, it was detected from 24 hr at pH 6.0 and from 48 hr at other pHs. The SEQ production was consistently 100-1,000 times less than that of SEA. These results suggest that the new-type enterotoxin SEQ has the potential to evoke symptoms related to SFP following the consumption of egg products cooked under relative lower pH and water activity.

Development of a sandwich ELISA for the thrombin light chain identified by serum proteome analysis.

We previously identified novel biomarker candidates in biliary tract cancer (BTC) using serum proteome analysis. Among several candidates, we focused on thrombin light chain which is a 4204 Da peptide as the most promising biomarker for BTC. To move thrombin light chain toward potential diagnostic use, we developed an enzyme immunoassay that enables to measure serum thrombin light chain levels. Both one monoclonal antibody specific to the N-termini and one polyclonal antibody were used to develop a sandwich ELISA for thrombin light chain. The assay was evaluated by comparing the results with those obtained by the ClinProt™ system. Serum samples were obtained from 20 patients with BTC, 20 patients with BBTDs and 20 HVs using the ClinProt™ system and ELISA. The results of the established ELISA showed a positive correlation with the findings by ClinProt™ system (slope=0.3386, intercept=34.901, r2=0.9641). The performance of the ELISA was satisfactory in terms of recovery (97.9-102.5%) and within-run (1.5-4.8%) and between-day (1.9-6.7%) reproducibility. Serum thrombin light chain levels were significantly greater in BTC (176.5±47.2 ng/mL) than in BBTDs (128.6±17.4 ng/mL) and HVs (127.6±16.0 ng/mL) (p<0.001). The sandwich ELISA developed in this study will be useful for validation of the diagnostic significance of serum thrombin light chain levels in various cancers.

Rapid Discrimination between Methicillin-Sensitive and Methicillin-Resistant Staphylococcus aureus Using MALDI-TOF Mass Spectrometry.

　Methicillin-resistant Staphylococcus aureus (MRSA) is one of the major pathogens responsible for nosocomial infections. The presence of MRSA in a hospital is detrimental to patients and to hospital management. Thus, rapid identification of MRSA is needed. Here, we report on a prospective method to rapidly discriminate of MSSA from MRSA using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and support vector machine (SVM) analysis in 160 clinical isolates of S. aureus. The predictive model was tested using 100 S. aureus isolates (50 MSSA and 50 MRSA). The identification rates were 90.0% for MSSA and 87.5% for MRSA in a 10-fold cross-validation SVM. In blind test sets, 60 S. aureus isolates (30 MSSA and 30 MRSA) were correctly classified, with identification rates of 93.3% for MSSA and 86.7% for MRSA. The method proposed in this study using the predictive model enables detection of one colony in 5 minutes, and thus is useful at clinical sites at which rapid discrimination of MRSA from MSSA is required.

Isolation, Identification and Antibacterial Susceptibility of Staphylococcus spp. Associated with the Mobile Phones of University Students.

From May 2014 to February 2015, 319 university students (male, n=173; female n=146) of 18 to 24 years of age who carried mobile phones or computer tablets were selected as subjects. Staphylococcus spp. were detected in 101 of 319 samples (31.7%). In the present study, 11 strains of S. aureus were isolated and identified, not all of which were methicillin-resistant Staphylococcus aureus (MRSA). Overall, 14 species were identified, with 11 strains (10.9%) of S. xylosus being isolated at the highest frequency. Following this were eight strains (7.9%) of S. cohnii and seven strains (6.9%) each of S. capitis and S. haemolyticus. Staphylococcus spp. isolation was performed with bacterial samples obtained from the mobile phones of 22 specific subjects (males, n=12; females, n=10). Staphylococcus spp. isolation was performed on days -1, 7 and 30 of the experiment. Staphylococcus spp. were positively detected one or more times in 12 subjects (54.5%). In one subject (8.3%), all three tests were positive. Furthermore, two tests were positive in three (25.0%). In the eight remaining subjects (66.7%) Staphylococcus spp. were detected only once. For the three abovementioned tests, we investigated the pulsed-field gel electrophoresis (PFGE) patterns of the strains derived from the mobile phone and from the fingers of three subjects in whom the same bacterial species were isolated twice. From the cases with similarities between strains derived from the fingers and the mobile phones and cases, with consistency in the strains derived from the mobile phone at different times, commonality was observed in the strains derived from the fingers and mobile phones along with chronological uniformity in the strains derived from the mobile phones. A total of 101 Staphylococcus spp. strains were isolated from mobile phones. According to drug susceptibility tests, 99 strains (98.0%) were found to have some degree of resistance to drugs (excluding one strain each of S. aureus and S. haemolyticus). Among these, the strain that showed the highest level of drug resistance was one strain (1.0%) of Staphylococcus spp., which showed resistance to nine drugs. The strain that showed the second highest level of drug resistance was one strain (1.0%) of S. caprea, which showed resistance to seven drugs. In this manner, the drug-resistant tendencies of Staphylococcus spp. isolated from mobile phones were observed.

Legionella thermalis sp. nov., isolated from hot spring water in Tokyo, Japan.

Strain L-47(T) of a novel bacterial species belonging to the genus Legionella was isolated from a sample of hot spring water from Tokyo, Japan. The 16S rRNA gene sequences (1477 bp) of this strain (accession number AB899895) had less than 95.0% identity with other Legionella species. The dominant fatty acids of strain L-47(T) were a15:0 (29.6%) and the major ubiquinone was Q-12 (71.1%). It had a guanine-plus-cytosine content of 41.5 mol%. The taxonomic description of Legionella thermalis sp. nov. is proposed to be type strain L-47(T) (JCM 30970(T) = KCTC 42799(T)).

Investigation of Legionella Contamination in Bath Water Samples by Culture, Amoebic Co-Culture, and Real-Time Quantitative PCR Methods.

We investigated Legionella contamination in bath water samples, collected from 68 bathing facilities in Japan, by culture, culture with amoebic co-culture, real-time quantitative PCR (qPCR), and real-time qPCR with amoebic co-culture. Using the conventional culture method, Legionella pneumophila was detected in 11 samples (11/68, 16.2%). Contrary to our expectation, the culture method with the amoebic co-culture technique did not increase the detection rate of Legionella (4/68, 5.9%). In contrast, a combination of the amoebic co-culture technique followed by qPCR successfully increased the detection rate (57/68, 83.8%) compared with real-time qPCR alone (46/68, 67.6%). Using real-time qPCR after culture with amoebic co-culture, more than 10-fold higher bacterial numbers were observed in 30 samples (30/68, 44.1%) compared with the same samples without co-culture. On the other hand, higher bacterial numbers were not observed after propagation by amoebae in 32 samples (32/68, 47.1%). Legionella was not detected in the remaining six samples (6/68, 8.8%), irrespective of the method. These results suggest that application of the amoebic co-culture technique prior to real-time qPCR may be useful for the sensitive detection of Legionella from bath water samples. Furthermore, a combination of amoebic co-culture and real-time qPCR might be useful to detect viable and virulent Legionella because their ability to invade and multiply within free-living amoebae is considered to correlate with their pathogenicity for humans. This is the first report evaluating the efficacy of the amoebic co-culture technique for detecting Legionella in bath water samples.

Bacterial contamination in cold water samples obtained from water dispensers.

We carried out a basic study in order to evaluate the bacterial contamination in water dispensers. Water samples were obtained from water dispensers from October 2012 to November 2013, and standard plate counts (at 36˚C, 24 h) of the samples, as well as heterotrophic plate counts (at 25˚C, 7 d), were estimated with the standard methods for the examination of drinking water in Japan. Standard plate counts exceeding the water-quality standard (1.0×10(2) CFU/ml) were observed in 42 of the 140 samples (30.0%), with a maximum detected bacterial count of 2.1×10(5) CFU/ml. The rate of the standard plate counts exceeding the water quality standard tended to be higher when using a one-way type method or water dispensers with natural water. Ralstonia spp. was most commonly isolated, and Pseudomonas aeruginosa was isolated in a few cases. Some opportunistic pathogens were also isolated, suggesting that we should be more concerned about bacterial contamination in cold water supplied from water dispensers.

Antibacterial susceptibility of enterobacteriaceae isolated from raw horsemeat isolated for human consumption (basashi).

Drug susceptibility testing was carried out using 14 antibiotics in order to identify trends in the antibiotic tolerance of 142 strains of Enterobacteriaceae isolated from horsemeat commercially available for raw consumption (basashi). A comparison of the sensitivity to the 14 antibiotics using the 90% MIC (minimum inhibitory concentration) values (MIC90) showed the strongest tolerance to ampicillin (ABPC) at a concentration of > 128 µg/mL, followed by that to fosfomycin (FOM) at a concentration of 128 µg/mL. When the sensitivity to these antibiotics was examined for each individual genus of tested bacteria, Hafnia spp. exhibited relative tolerance to ceftazidime (CAZ) and ceftriaxone (CTRX) at a concentration of 4 µg/mL and 2 µg/mL, respectively, which was high in comparison to that observed for the other strains. Furthermore, Raoultella spp. and Serratia spp. were found to be highly resistant to tetracycline (TC) at a concentration of 128 µg/mL and 64 µg/mL, respectively. Of the 142 strains of test bacteria, 140 (98.6%) demonstrated resistance to ABPC, with the exception of Hafnia alvei and Klebsiella pneumonia. In addition, a total of eight strains (5.6%), seven Serratia marcescens strains and one Raoultella terrigena strain, were found to be resistant to TC. Furthermore, one strain of Citrobacter freundii exhibited resistance to nalidixic acid (NA), while another displayed resistance to ofloxacin (OFLX) (0.7% each), and one strain (0.7%) each of Enterobacter cloacae, Serratia marcescens and Citrobacter youngae demonstrated resistance to fosfomycin (FOM), streptomycin (SM) and kanamycin (KM), respectively. A single strain of C. freundii was found to be resistant to three antibiotics, ABPC, NA and OFLX. Resistance to two antibiotics was confirmed in 11 strains, including seven strains of S. marcescens and one strain of R. terrigena (a total of eight strains) resistant to ABPC and TC, and one strain each of C. youngae, S. marcescens and E. cloacae resistant to ABPC and KM, ABPC and SM, and ABPC and FOM, respectively. In addition, 128 strains were resistant to the single antibiotic of ABPC alone. Of the 140 strains demonstrating antibiotic resistance, 137 (97.9%) retained the conjugative R-plasmid transfer factor, excluding three strains of S. marcescens. All transfer factors were ABPC and retained by a high proportion of the bacterial groups, with one strain (100%) being resistant to three antibiotics, nine (81.8%) of the 11 strains being resistant to two antibiotics, and 127 (99.2%) of the 128 strains being resistant to a single antibiotic. In addition, we examined ESBL productivity in the 140 strains of bacteria demonstrating drug tolerance; however, no strains exhibited this characteristic. Therefore, further observation is required to ascertain trends in antibiotic-tolerant bacteria.

Pulsed-Field Gel Electrophoresis (PFGE) pattern analysis and chlorine-resistance of Legionella pneumophila isolated from hot spring water samples.

For a microbial ecological analysis, 20 strains of Legionella pneumophila isolated from both unchlorinated Noyu (unattended natural hot spring) samples and chlorinated hot spring bath water samples collected throughout Japan were subjected to a clustering analysis on the basis of a Pulsed-Field Gel Electrophoresis (PFGE) pattern analysis. The PFGE patterns obtained from 19 strains of L. pneumophila after digestion with SfiI were used to divide the strains into two groups (Groups A and B), although the similarity level was very low among the groups. Group A consisted of 8 strains, and all of these strains were isolated from hot spring bath water samples. Group B consisted of 11 strains, and all but two of these strains were isolated from Noyu samples. The chlorine resistance (99.9% CT values) of these isolates was experimentally confirmed, and we attempted to define the relationship between chlorine resistance and the geno-cluster. The average CT value of group A (8 strains from hot spring bath water) was 0.49 mgï½¥min/l and the average of group B (9 strains from Noyu samples) was 0.29 mgï½¥min/l. No remarkable differences in the CT values for the groups were found. A chlorine-sensitive Noyu strain (0.14 mgï½¥min/l) and a chlorine-resistant strain (0.62 mgï½¥min/l) from hot spring bath water were then compared to identify any differences in their lipid composition. There was no notable difference in the ratio of saturated to unsaturated fatty acids between the chlorine-sensitive and chlorine-resistant bacteria. However, the chlorine-sensitive and chlorine-resistant bacteria demonstrated differences in the relative percentages of cell wall and cell membrane fatty acids.

New application of indirect fluorescent antibody (IFA) technique using latex particles coupled with verotoxin 2 from Escherichia coli O157:H7 in order to determine colostral antibody titers in immunized dairy cows.

A simple and novel assay method for determining colostral and serum against soluble verotxin 2 (VT2) titers by indirect fluorescent antibody (IFA) assay using latex sensitized with VT2 was devised. The latex particles did not auto-fluoresce, and non specific reactions disappeared after washing with phosphate buffered saline containing 3 M Nacl. The highest titer measured by neutralizing test was observed at 1 day after delivery. The highest titer for each immunoglobulin class measured by enzyme-linked immunosorbent assay (ELISA) or IFA using latex sensitized with VT2 was also observed at 1 day after delivery. The changes in titer measured by each method showed similar patterns. Furthermore, the titers for IgG antibody were higher than those for IgM or IgA antibodies. Thus, the titers of bovine immune colostral antibody and each immunoglobulin class could be measured by IFA using latex sensitized with VT2.

Isolation and identification of Enterobacteriaceae from raw horsemeat intended for human consumption (Basashi).

The status of Enterobacteriaceae contamination was investigated in a total of 131 samples of raw horsemeat (Basashi) intended for human consumption purchased from a general meat shop or by mail-order from October 2012 to December 2013. The bacteria were isolated from 105 of the 112 samples (93.8%). Prominent differences in the isolation rate due to the place of manufacture/sale or by the cut of the meat were not observed. Moreover, in a comparison between domestic (92.6%) and imported (100%) samples, the isolation rate was slightly higher in the imported samples. When Enterobacteriaceae isolated from raw horsemeat was identified, it was highly diverse, with 14 species identified in total. From among these species, Hafnia alvei was the most common, with 33 strains (19.8%),followed by 27 strains (16.2%) of Klebsiella pneumoniae and 26 strains (15.6%) of Enterobacter cloacae, indicating that these three species were dominant. A trend was observed, with the dominant strain differing depending on the place of manufacture/sale or the cut of the meat. H. alvei was isolated at an especially high frequency from imported samples. An investigation was carried out regarding raw horsemeat intended for human consumption from Yamanashi Prefecture and Canada, regularly purchased from one store in Kanagawa Prefecture. Enterobacteriaceae were isolated during five of nine (55.6%） trials, in which the isolated bacteria were H. alvei, K. pneumoniae, etc. Moreover, they were isolated at a very high isolation rate of seven among 10 trials for the Canadian meat, and H. alvei was the most commonly isolated bacteria. Accordingly, when an investigation was carried out regarding the differences in the strain level in the six isolates of H. alvei periodically isolated from raw horsemeat from Canada by the pulsed-field gel electrophoresis (PFGE) pattern using a restriction enzyme, SfiI, there was a possibility that these were the same H-38 strain (November 2013) and H-64 strain (April 2014) as well as the same H-104 strain (July 2014) and H-131 strain (December 2014). As mentioned above, it has been demonstrated that a variety of Enterobacteriaceae were isolated from raw horsemeat (Basashi) intended for human consumption, and at a high frequency. Moreover, based on the fact that the same species or strain was chronologically isolated, the possibility of contamination by the same contamination source at different times was suggested.

Roseomonas tokyonensis sp. nov. isolated from a biofilm sample obtained from a cooling tower in Tokyo, Japan.

Strain K-20(T), a Gram-negative, nonmotile, nonspore-forming and strictly aerobic coccobacillus, which produces a pale pink pigment (R2A agar medium, 30℃, seven days) was isolated from a sample of biofilm obtained from a cooling tower in Tokyo, Japan. A phylogenetic analysis of the 16S rRNA partial gene sequences (1,439 bp) showed that the strain (accession number: AB297501) was related to Roseomonas frigidaquae CW67(T) and Roseomonas stagni HS-69(T) with 97.4% and 96.9% sequence similarity, respectively. Strain K-20(T) formed a distinct cluster with Roseomonas frigidaquae CW67(T) in the phylogenetic tree at a high bootstrap value (93%); however, distance was recognized between the strains. In addition, the DNA-DNA hybridization level between strain K-20(T) and Roseomonas frigidaquae JCM 15073(T) was 33%. The taxonomic data indicate that K-20(T) (=JCM 14634(T) =KCTC 32152(T)) should be classified in the genus Roseomonas as the type strain of a novel species, Roseomonas tokyonensis sp. nov.

Isolation of Legionella species from Noyu (unattended natural hot springs in mountains and fields) samples in Japan.

In order to understand the habitation conditions of the bacteria of the genus Legionella in Noyu (unattended natural hot springs in mountains and fields) in Japan, isolation of Legionella spp. was attempted in the Noyu samples from 11 prefectures nationwide between May and September 2012, and the following results were obtained. Overall, Legionella spp. was isolated from 16 of 43 samples (37.2%). The species was isolated from the Hokkaido region to the Chugoku region but not from the Shikoku region to the Kyushu region. The number of bacteria detected was usually small, less than 5.0 × 10(1) CFU/100 ml, as found in 11 samples (68.8%), while counts of 10(2) or more to 10(3) or less CFU/100 ml were found in two samples (12.5%). Legionella pneumophila was the most commonly found strain, with 19 strains (90.5%) found, and was the dominant species. Regarding the serogrouping, four strains (21.1%) fell under group 1, the most common grouping, followed by three strains (15.8%) in group 3, two strains (10.5%) in group 5, etc. Moreover, the detected bacterial strains other than L. pneumophila included two strains (9.5%) of L. londiniensis. The temperature of the Noyu from which Legionella spp. was isolated was between 33.1°C and 41.5°C with a pH ranging from 5.2 to 8.1. The present report is the first report to clarify the habitation conditions of strains of Legionella spp. isolated from Noyu in Japan.

Characteristics of an orange-pigmented bacterium isolated from a hot spring in Kagoshima, Japan.

In May 2012, strain HNN-6 (=JCM 18566) , a Gram-negative, non-spore-forming, motile and strictly aerobic rod, which produces a pale orange pigment, was isolated from a hot spring water sample obtained in Kagoshima, Japan, by a plating method using R2A medium at 30°C for 7 d. The 16S rRNA gene sequences (1,437bp) of this strain (accession number: AB731137) had a close similarity (99.1%) to Hydrotalea sandarakina AF-51T (JF739858) . Growth occurred at 25-45°C and pH 5.0-8.0, with optimal growth at 40°C and pH 6.0-7.0. Growth did not occur in the presence of ≧2% NaCl. The API 20NE identification system gave positive results for nitrate, aesculin, gelatin, 4-nitrophenyl-ß-D-galactopyranoside, D-glucose, D-mannose, maltose and oxidase (API code number 1472204) . The dominant cellular fatty acids of strain HNN-6 were iso-C15:0 (32.6%) , iso-C17:0 3-OH (24.2%) and iso-C16:0 (8.4%) . The guanine-plus-cytosine (G+C) content of DNA was 36.2 mol%. This article is the first report to describe the characteristics of an orange-pigmented bacterium isolated from a hot spring water sample in Japan.

[Isolation of Legionella species from hot springs used for foot-soaking].

OBJECTIVES: We aimed to investigate the presence of Legionella species in hot-spring baths for feet, which have been rapidly increasing in number in Japan in recent years. METHODS: The investigations were conducted between March 2009 and November 2011, and hot springs throughout the country were sampled. Legionella isolates were confirmed on the basis of the method described in the "Manual for the countermeasure to legionellosis, 3rd Edition." In this method, the samples were concentrated and smeared on GVPCalpha agar medium after acid treatment and cultured for 7 days at 36 degrees C. Gram-negative rods that required L-cysteine were determined to be Legionella species. After the first identification using Duopath Legionella (Merck Ltd. Japan), isolates were identified on the basis of agglutination reaction of an immune serum or genetic examination. RESULTS: Legionella was isolated from 56 of the 196 samples (28.6%) and was confirmed to widely inhabit hot-spring baths from Hokkaido to Kyushu. The isolation rates were the highest (40.9%) in facilities installed around railway stations, including those on platforms. The average microbial density of Legionella species per 100 ml of hot spring water was 1.0 x 10(1) CFU, with a maximum value of 1.0 x 10(4) CFU, although the microbial density in most of the samples (34 samples; 60.7%) was less than 10(2) CFU. Legionella pneumophila was the dominant strain, and 16 strains (23.9%) of serogroup 1 were isolated. In addition, 7 strains (10.4%) of Legionella londiniensis and 4 strains (6.0%) of Legionella rubrilucens were isolated. CONCLUSION: Legionella species inhabit approximately 30% of all hot springs for foot-soaking in the country. Although the number of viable organisms is small, the dominant presence of Legionella pneumophila, a major pathogen responsible for legionnaire's disease, raises the possibility of legionnaire's disease in users of these hot springs. Therefore, each institute should understand the present distribution of Legionella species in these hot springs and undertake appropriate sanitary measures.

Identification of Legionella rubrilucens isolated from a hot spring for foot-soaking in Niigata, Japan.

In May 2011, strain HYNE-20 (=JCM 17837) was isolated from a sample of hot spring water from a foot spa in Niigata, Japan, by a plating method using glycine vancomycin polymyxin B cycloheximide α-ketoglutarate (GVPCα) medium at 36°C for 7 d. The 16S rDNA sequences (1,469bp) of this strain (accession number: AB638719) had high (99.7%) similarity to Legionella rubrilucens, and we identified that this strain was indeed Legionella rubrilucens. When this strain was cultured on buffered charcoal yeast extract α-ketoglutarate (BCYEα) agar at 36°C for 7 d, it exhibited red autofluorescence under UV light (365 nm) . The dominant cellular fatty acids of the strain HYNE-20 were 16:1ω7c (29.9%) , and the guanine-plus-cytosine (G+C) content of DNA was 49.0 mol%. This is the first report that Legionella rubrilucens was isolated from a hot spring for foot soaking.

Distribution of monoclonal antibody subgroups and sequence-based types among Legionella pneumophila serogroup 1 isolates derived from cooling tower water, bathwater, and soil in Japan.

Legionella pneumophila serogroup (SG) 1 is the most frequent cause of legionellosis. This study analyzed environmental isolates of L. pneumophila SG 1 in Japan using monoclonal antibody (MAb) typing and sequence-based typing (SBT). Samples were analyzed from bathwater (BW; n = 50), cooling tower water (CT; n = 50), and soil (SO; n = 35). The distribution of MAb types varied by source, with the most prevalent types being Bellingham (42%), Oxford (72%), and OLDA (51%) in BW, CT, and SO, respectively. The ratios of MAb 3/1 positive isolates were 26, 2, and 14% from BW, CT, and SO, respectively. The environmental isolates from BW, CT, and SO were divided into 34 sequence types (STs; index of discrimination [IOD] = 0.973), 8 STs (IOD = 0.448), and 11 STs (IOD = 0.879), respectively. Genetic variation among CT isolates was smaller than seen in BW and SO. ST1 accounted for 74% of the CT isolates. The only common STs between (i) BW and CT, (ii) BW and SO, and (iii) CT and SO were ST1, ST129, and ST48, respectively, suggesting that each environment constitutes an independent habitat.