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Human tumors harbor a plethora of microbiota. It has been shown that the composition and diversity of intratumor microbiome are significantly associated with the survival of patients with pancreatic ductal adenocarcinoma (PDAC). However, the association in Chinese patients as well as the effect of different microorganisms on inhibiting tumor growth are unclear. In this study, we collected tumor samples resected from long-term and short-term PDAC survivors and performed 16S rRNA amplicon sequencing. We found that the microbiome in samples with different survival time were significantly different, and the differential bacterial composition was associated with the metabolic pathways in the tumor microenvironment. Furthermore, administration of Megasphaera , one of the differential bacteria, induced a better tumor growth inhibition effect when combined with the immune checkpoint inhibitor anti-programmed cell death-1 (anti-PD-1) treatment in mice bearing 4T1 tumor. These results indicate that specific intratumor microbiome can enhance the anti-tumor effect in the host, laying a foundation for further clarifying the underlying detailed mechanism., Competing Interests: Authors NZ, XZ, YHL, HL, XY, HJH, YT, HH, YL, and YY are employed by Xbiome Biotech Co. Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Huang, Zhu, Zheng, Liu, Lu, Yin, Hao, Tan, Wang, Hu, Liang, Li, Hu and Yin.)

The composition of the human vaginal microbiome has been extensively studied and is known to influence reproductive health. However, the functional roles of individual taxa and their contributions to negative health outcomes have yet to be well characterized. Here, we examine two vaginal bacterial taxa grouped within the genus Megasphaera that have been previously associated with bacterial vaginosis (BV) and pregnancy complications. Phylogenetic analyses support the classification of these taxa as two distinct species. These two phylotypes, Megasphaera phylotype 1 (MP1) and Megasphaera phylotype 2 (MP2), differ in genomic structure and metabolic potential, suggestive of differential roles within the vaginal environment. Further, these vaginal taxa show evidence of genome reduction and changes in DNA base composition, which may be common features of host dependence and/or adaptation to the vaginal environment. In a cohort of 3870 women, we observed that MP1 has a stronger positive association with bacterial vaginosis whereas MP2 was positively associated with trichomoniasis. MP1, in contrast to MP2 and other common BV-associated organisms, was not significantly excluded in pregnancy. In a cohort of 52 pregnant women, MP1 was both present and transcriptionally active in 75.4 % of vaginal samples. Conversely, MP2 was largely absent in the pregnant cohort. This study provides insight into the evolutionary history, genomic potential and predicted functional role of two clinically relevant vaginal microbial taxa.

Dysbiosis, or imbalance in the gut microbiome, has been implicated in auto-immune, inflammatory, neurological diseases as well as in cancers. More recently it has also been shown to be associated with ocular diseases. In the present study, the association of gut microbiome dysbiosis with bacterial Keratitis, an inflammatory eye disease which significantly contributes to corneal blindness, was investigated. Bacterial and fungal gut microbiomes were analysed using fecal samples of healthy controls (HC, n = 21) and bacterial Keratitis patients (BK, n = 19). An increase in abundance of several antiinflammatory organisms including Dialister, Megasphaera, Faecalibacterium, Lachnospira, Ruminococcus and Mitsuokella and members of Firmicutes, Veillonellaceae, Ruminococcaceae and Lachnospiraceae was observed in HC compared to BK patients in the bacterial microbiome. In the fungal microbiome, a decrease in the abundance of Mortierella, Rhizopus, Kluyveromyces, Embellisia and Haematonectria and an increase in the abundance of pathogenic fungi Aspergillus and Malassezia were observed in BK patients compared to HC. In addition, heatmaps, PCoA plots and inferred functional profiles also indicated significant variations between the HC and BK microbiomes, which strongly suggest dysbiosis in the gut microbiome of BK patients. This is the first study demonstrating the association of gut microbiome with the pathophysiology of BK and thus supports the gut-eye axis hypothesis. Considering that Keratitis affects about 1 million people annually across the globe, the data could be the basis for developing alternate strategies for treatment like use of probiotics or fecal transplantation to restore the healthy microbiome as a treatment protocol for Keratitis.

A novel mesophilic, anaerobic, Gram-stain-negative bacterium was isolated from the cecum of a healthy white leghorn chicken, and designated AJH120 T . Cells were coccoid or diplococcoid with an average size of 0.8-1.8 µm and were non-motile with no evidence of spores. Phylogenetic analysis of 16S rRNA gene sequences revealed this organism to be a member of the genus Megasphaera, with the closest relatives being Megasphaera elsdenii (95 % sequence identity) and Megasphaera cerevisiae (95 % sequence identity). Growth was observed between 30 and 50 °C and between pH 5.0 and 9.0. AJH120 T utilized a variety of carbon sources, including succinate, gluconate, fructose, ribose and pyruvate, as well as many individual amino acids. The DNA G+C content for the genome sequence of AJH120 T was 52.1 mol%. Digital DNA-DNA hybridization (dDDH), average nucleotide identity (ANI) and average amino acid identity (AAI) between AJH120 T and close taxonomic relatives, indicated divergence consistent with the strain representing a novel species. The major fatty acid methyl esters of the organism were C12 : 0, C14 : 0 3-OH, C18 : 1ω9c, C16 : 0 and C16 : 1ω9c. AJH120 T was able to produce several short chain fatty acids, including butyrate, acetate, propionate and isovalerate. Together, these data indicate that AJH120 T represents a novel species within the genus Megasphaera. We propose the name Megasphaerastantonii sp. nov. for the species. The type strain of this species is AJH120 T (=DSM 106750 T =CCUG 71842 T ).

Strain MHT, a strictly anaerobic, Gram-stain-negative, non-spore-forming, spherical coccus or coccoid-shaped microorganism, was isolated from a cow rumen during a screen for hexanoic acid-producing bacteria. The microorganism grew at 30-40 °C and pH 5.5-7.5 and exhibited production of various short- and medium-chain carboxylic acids (acetic acid, butyric acid, pentanoic acid, isobutyric acid, isovaleric acid, hexanoic acid, heptanoic acid and octanoic acid), as well as H2 and CO2 as biogas. Phylogenetic analysis based on 16S rRNA gene sequencing demonstrated that MHT represents a member of the genus Megasphaera, with the closest relatives being Megapsphaera indica NMBHI-10T (94.1 % 16S rRNA sequence similarity), Megasphaera elsdenii DSM 20460T (93.8 %) and Megasphaera paucivorans DSM 16981T (93.8 %). The major cellular fatty acids produced by MHT included C12 : 0, C16 : 0, C18 : 1cis 9, and C18 : 0, and the DNA G+C content of the MHT genome is 51.8 mol%. Together, the distinctive phenotypic and phylogenetic characteristics of MHT indicate that this microorganism represents a novel species of the genus Megasphaera, for which the name Megasphaera hexanoica sp. nov. is herein proposed. The type strain of this species is MHT (=KCCM 43214T=JCM 31403T).

Much of the work in periodontal microbiology in recent years has focused on identifying and understanding periodontal pathogens. As the majority of oral microbes have not yet been isolated in pure form, it is essential to understand the phenotypic characteristics of microbes to decipher their role in oral environment. In this study, strain DISK18 was isolated from gingival sulcus and identified as a Megasphaera species. Although metagenomics studies revealed Megasphaera species as a major group within the oral habitat, they have never been isolated in cultivable form to date. Therefore, we have characterized the DISK18 strain to better understand its role in the periodontal ecosystem. Strain Megasphaera sp. DISK18 displayed the ability to adhere and self-aggregate, which are essential requisite features for inhabiting and persisting in oral cavity. It also coaggregated with other pioneer oral colonizers like Streptococcus and Lactobacillus species but not with Veillonella. This behaviour points towards its role in the ecologic succession of a multispecies biofilm as an early colonizer. The absence of virulence determining genes as observed in whole genome sequence analysis coupled with an inability to degrade collagen reveals that Megasphaera sp. strain DISK18 is likely not a pathogenic species and emphasizes its commensal lifestyle.

Recent studies showing clear differences in the airway microbiota between healthy and diseased individuals shed light on the importance of the airway microbiota in health. Here, we report the associations of host genetics and lifestyles such as smoking, alcohol consumption, and physical activity with the composition of the sputum microbiota using 16S rRNA gene sequence data generated from 257 sputum samples of Korean twin-family cohort. By estimating the heritability of each microbial taxon, we found that several taxa, including Providencia and Bacteroides, were significantly influenced by host genetic factors. Smoking had the strongest effect on the overall microbial community structure among the tested lifestyle factors. The abundances of Veillonella and Megasphaera were higher in current-smokers, and increased with the pack-year value and the Fagerstrom Test of Nicotine Dependence (FTND) score. In contrast, Haemophilus decreased with the pack-year of smoking and the FTND score. Co-occurrence network analysis showed that the taxa were clustered according to the direction of associations with smoking, and that the taxa influenced by host genetics were found together. These results demonstrate that the relationships among sputum microbial taxa are closely associated with not only smoking but also host genetics.

Electrospray ionization-tandem mass spectrometry (ESI-MS/MS) was used for characterizing intact plasmalogen phospholipid molecules in beer-spoilage bacteria. Identification of intact plasmalogens was carried out using collision-induced dissociation and the presence of suitable marker molecular species, both qualitative and quantitative, was determined in samples containing the anaerobic bacteria Megasphaera and Pectinatus. Using selected ion monitoring (SIM), this method had a limit of detection at 1 pg for the standard, i.e. 1-(1Z-octadecenyl)-2-oleoyl-sn-glycero-3-phosphoethanolamine and be linear in the range of four orders of magnitude from 2 pg to 20 ng. This technique was applied to intact plasmalogen extracts from the samples of contaminated and uncontaminated beer without derivatization and resulted in the identification of contamination of beer by Megasphaera and Pectinatus bacteria. The limit of detection was about 830 cells of anaerobic bacteria, i.e. bacteria containing natural cyclopropane plasmalogenes (c-p-19:0/15:0), which is the majority plasmalogen located in both Megasphaera and Pectinatus. The SIM ESI-MS method has been shown to be useful for the analysis of low concentration of plasmalogens in all biological samples, which were contaminated with anaerobic bacteria, e.g. juice, not only in beer. Significance and impact of the study: Electrospray ionization-tandem mass spectrometry (ESI-MS/MS) using collision-induced dissociation was used to characterize intact plasmalogen phospholipid molecules in beer-spoilage anaerobic bacteria Megasphaera and Pectinatus. Using selected ion monitoring (SIM), this method has a detection limit of 1 pg for the standard 1-(1Z-octadecenyl)-2-oleoyl-sn-glycero-3-phosphoethanolamine and is linear within four orders of magnitude (2 pg to 20 ng). The limit of detection was about 830 cells of bacteria containing natural cyclopropane plasmalogen (c-p-19:0/15:0). SIM ESI-MS method is useful for analyzing low concentrations of plasmalogens in biological samples contaminated with anaerobic bacteria, e.g. beer or juice., (© 2015 The Society for Applied Microbiology.)

Two coccoid, non-motile, obligately anaerobic, Gram-stain-negative bacteria, occurring singly or in pairs, or as short chains, with a mean size of 1.4-2.5 µm were isolated from the faeces of two healthy human volunteers, aged 26 and 56 years, and were designated NMBHI-10(T) and BLPYG-7, respectively. Both the strains were affiliated to the sub-branch Sporomusa of the class Clostridia as revealed by 16S rRNA gene sequence analysis. The isolates NMBHI-10(T) and BLPYG-7 showed 99.1 and 99.2% 16S rRNA gene sequence similarity, respectively, with Megasphaera elsdenii JCM 1772(T). DNA-DNA hybridization and phenotypic analysis showed that both the strains were distinct from their closest relative, M. elsdenii JCM 1772(T) (42 and 53% DNA-DNA relatedness with NMBHI-10(T) and BLPYG-7, respectively), but belong to the same species (DNA-DNA relatedness of 80.9 % between the isolates). According to DNA-DNA hybridization results, the coccoid strains belong to the same genospecies, and neither is related to any of the recognized species of the genus Megasphaera. Strains NMBHI-10(T) and BLPYG-7 grew in PYG broth at temperatures of between 15 and 40 °C (optimum 37 °C), but not at 45 °C. The strains utilized a range of carbohydrates as sources of carbon and energy including glucose, lactose, cellobiose, rhamnose, galactose and sucrose. Glucose fermentation resulted in the formation of volatile fatty acids, mainly caproic acid and organic acids such as succinic acid. Phylogenetic analysis, specific phenotypic characteristics and/or DNA G+C content also differentiated the strains from each other and from their closest relatives. The DNA G+C contents of strains NMBHI-10(T) and BLPYG-7 are 57.7 and 54.9 mol%, respectively. The major fatty acids were 12 : 0 FAME and 17 : 0 CYC FAME. On the basis of these data, we conclude that strains NMBHI-10(T) and BLPYG-7 should be classified as representing a novel species of the genus Megasphaera, for which the name Megsphaera indica sp. nov. is proposed. The type strain is NMBHI-10(T) ( = DSM 25563(T) = MCC 2481(T))., (© 2014 IUMS.)

Introduction: A significant portion of the bacteria taking part of the microbiome associated with apical periodontitis still remain to be cultivated and phenotypically characterized. This molecular study evaluated the prevalence of selected as-yet-uncultivated and difficult-to-culture bacterial taxa in infected root canals and their susceptibility to chemomechanical procedures., Methods: Root canals of single-rooted teeth with apical periodontitis were prepared using rotary nickel-titanium instruments and 2.5% sodium hypochlorite as the irrigant. DNA extracts from samples taken before (S1) and after (S2) chemomechanical preparation were surveyed for the presence of 7 as-yet-uncultivated phylotypes and 1 difficult-to-culture species using end-point polymerase chain reaction. Samples were also subjected to quantitative analysis of total bacteria and levels of the 2 most prevalent taxa., Results: Bacteroidaceae sp. HOT-272 (24%) and Fretibacterium fastidiosum (20%) were the most prevalent taxa in S1. Their mean counts in S1 were 8.25 × 10(3) and 2.13 × 10(3) rRNA gene copies, corresponding to 0.18% and 0.55% of the total bacteria. Chemomechanical debridement promoted a highly statistically significant reduction in total bacterial counts (P < .001), but 64% of the canals were still positive for bacterial presence. Of the target taxa, only Bacteroidaceae sp. HOT-272 and F. fastidiosum were detected in S2 (each one in 1 sample). The reduction in counts of both taxa was also highly significant (P < .001)., Conclusions: Findings confirmed that several as-yet-uncultivated and difficult-to-grow bacterial taxa can participate in the microbiome associated with apical periodontitis. Two of them were found in relatively high prevalence but rarely as a dominant species. Chemomechanical procedures were highly effective in completely eliminating these taxa or at least substantially reducing their numbers., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

With increasing number of novel bacteria being isolated from the human gut ecosystem, there is a greater need to study their role in the gut ecosystem and their effect on the host health. In the present study, we carried out in silico genome-wide analysis of two novel Megasphaera sp. isolates NM10 (DSM25563) and BL7 (DSM25562), isolated from feces of two healthy individuals and validated the key features by in vitro studies. The analysis revealed the general metabolic potential, adaptive features and the potential effects of these isolates on the host. The comparative genome analysis of the two human gut isolates NM10 and BL7 with ruminal isolate Megasphaera elsdenii (DSM20460) highlighted the differential adaptive features for their survival in human gut. The key findings include features like bile resistance, presence of various sensory and regulatory systems, stress response systems, membrane transporters and resistance to antibiotics. Comparison of the "glycobiome" based on the genomes of the ruminal isolate with the human gut isolates NM10 and BL revealed the presence of diverse and unique sets of Carbohydrate-Active enzymes (CAZymes) amongst these isolates, with a higher collection of CAZymes in the human gut isolates. This could be attributed to the difference in host diet and thereby the environment, consequently suggesting host specific adaptation in these isolates. In silico analysis of metabolic potential predicted the ability of these isolates to produce important metabolites like short chain fatty acids (butyrate, acetate, formate, and caproate), vitamins and essential amino acids, which was further validated by in vitro experiments. The ability of these isolates to produce important metabolites advocates for a potential healthy influence on the host. Further in vivo studies including transcriptomic and proteomic analysis will be required for better understanding the role and impact of these Megasphaera sp. isolates NM10 and BL7 on the human host.

The class Clostridia in the phylum Firmicutes (formerly low-G+C Gram-positive bacteria) includes diverse bacteria of medical, environmental and biotechnological importance. The Selenomonas-Megasphaera-Sporomusa branch, which unifies members of the Firmicutes with Gram-negative-type cell envelopes, was recently moved from Clostridia to a separate class Negativicutes. However, draft genome sequences of the spore-forming members of the Negativicutes revealed typically clostridial sets of sporulation genes. To address this and other questions in clostridial phylogeny, we have compared a phylogenetic tree for a concatenated set of 50 widespread ribosomal proteins with the trees for beta subunits of the RNA polymerase (RpoB) and DNA gyrase (GyrB) and with the 16S rRNA-based phylogeny. The results obtained by these methods showed remarkable consistency, suggesting that they reflect the true evolutionary history of these bacteria. These data put the Selenomonas-Megasphaera-Sporomusa group back within the Clostridia. They also support placement of Clostridium difficile and its close relatives within the family Peptostreptococcaceae; we suggest resolving the long-standing naming conundrum by renaming it Peptoclostridium difficile. These data also indicate the existence of a group of cellulolytic clostridia that belong to the family Ruminococcaceae. As a tentative solution to resolve the current taxonomical problems, we propose assigning 78 validly described Clostridium species that clearly fall outside the family Clostridiaceae to six new genera: Peptoclostridium, Lachnoclostridium, Ruminiclostridium, Erysipelatoclostridium, Gottschalkia and Tyzzerella. This work reaffirms that 16S rRNA and ribosomal protein sequences are better indicators of evolutionary proximity than phenotypic traits, even such key ones as the structure of the cell envelope and Gram-staining pattern., (Published 2013. This article is a U.S. Government work and is in the public domain in the USA.)

Background: Bacterial vaginosis frequently persists after treatment. The role of newly defined bacterial vaginosis-associated bacteria (BVAB), which have a specificity for this condition of 97% or greater, has not been assessed., Objective: To define risks for bacterial vaginosis persistence, including pretreatment detection of specific vaginal bacteria, among women reporting sex with women., Design: Observational cohort study., Setting: University-based research clinic., Patients: 335 women age 16 to 29 years reporting sex with at least 1 woman in the past year. Participants were recruited through advertisements and provider referral., Intervention: Bacterial vaginosis was treated with intravaginal metronidazole gel (0.75%), 37.5 mg nightly for 5 nights., Measurements: Species-specific 16S recombinant DNA polymerase chain reaction assays targeting 17 bacterial species were applied to vaginal fluid obtained at baseline. Test of cure by clinical criteria and Gram stain analysis and repeated polymerase chain reaction assays of vaginal fluid were performed 1 month after treatment, and interim behaviors were assessed by using computer-assisted self-interview., Results: Of 335 women, 24% of whom also reported sex with men within 3 months before enrollment, 131 (39%) had bacterial vaginosis. In the 120 (92%) women who returned for follow-up, the incidence of persistent bacterial vaginosis was 26% and was statistically significantly higher in women with baseline detection of 3 Clostridiales bacteria, designated as BVAB1 (risk ratio, 2.0 [95% CI, 1.1 to 4.0]), BVAB2 (risk ratio, 8.7 [CI, 2.5 to infinity]), or BVAB3 (risk ratio, 3.1 [CI, 1.7 to 5.8]); Peptoniphilus lacrimalis (risk ratio, 3.5 [CI, 1.6 to 15.5]); and Megasphaera phylotype 2 (risk ratio, 3.4 [CI, 1.4 to 5.5]). Persistence was lower with treatment adherence (risk ratio, 0.4 [0.2 to 0.9]). Detection of these bacteria at the test-of-cure visit was associated with persistence, whereas posttreatment sexual activity was not., Limitations: Findings may not be generalizable to women who have sex only with men, or to women whose bacterial vaginosis is treated with oral antibiotics. The study may be too small and may involve a population that is too highly selected to draw definitive conclusions about associations of persistent infection with posttreatment sexual behaviors., Conclusion: Persistent bacterial vaginosis is associated with several bacteria in the Clostridiales order, Megasphaera phylotype 2, and P. lacrimalis, suggesting that vaginal microbiology at diagnosis may determine risk for antibiotic failure.

Cultivation-independent analysis of 16S rRNA gene sequences in vaginal samples revealed two previously unrecognized, uncultivated Megasphaera-like phylotypes. Phylogenetic analysis and environmental distribution suggest that these Megasphaera types may be unique to the vaginal environment. Quantitative PCR suggests that both phylotypes are present in higher concentrations in women with bacterial vaginosis.

Seven unidentified strictly anaerobic, Gram-negative, non-spore-forming bacteria from spoiled beer or the brewery environment were characterized. Based on 16S rRNA gene sequence analyses, all strains were affiliated to the Sporomusa sub-branch of the class 'Clostridia'. Three of the strains were non-motile cocci, on average 1.5 x 1.2 microm or 1.2 x 1.0 microm, occurring mainly singly or in pairs. They shared nearly identical (>99 %) 16S rRNA gene sequences, being most closely related to the species of the Megasphaera-Anaeroglobus group (< or =93.9 % similarity). According to DNA-DNA hybridization results, the coccoid strains represented two genospecies, neither of which was related to any of the recognized Megasphaera species. Several phenotypic characteristics and/or DNA G+C content also differentiated the strains from each other and from their closest relatives. The other four novel strains were motile, slightly curved to helical rods, 0.6-0.8 x 3-50 microm or more in size. They shared identical 16S rRNA gene sequences and ribofragment patterns. The highest 16S rRNA gene similarity was found between these isolates and Pectinatus cerevisiiphilus ATCC 29359T (95.6 %) and Pectinatus frisingensis ATCC 33332T (93.6 %). The novel strains also differed from recognized Pectinatus species in their sugar utilization, proteolytic activity, catalase activity, antibiotic resistance and temperature tolerance. The results suggest that the bacteria belong to three novel species, for which the names Megasphaera paucivorans sp. nov. (type strain VTT E-032341T = DSM 16981T), Megasphaera sueciensis sp. nov. (type strain VTT E-97791T = DSM 17042T) and Pectinatus haikarae sp. nov. (type strain VTT E-88329T = DSM 16980T) are proposed.

The purpose of the present study was to use terminal restriction fragment length polymorphism analysis and the 16S rRNA gene clone library to investigate the diversity of the microbiota associated with asymptomatic and symptomatic endodontic infections and to compare the bacterial community structure in these two clinical conditions. Samples were taken from asymptomatic endodontic infections associated with chronic periradicular lesions and from symptomatic infections clinically diagnosed as acute abscesses. 16S rRNA genes from DNA isolated from clinical samples were used to construct clone libraries or were subjected to terminal restriction fragment length polymorphism analysis. Sequence analysis of 186 clones revealed 42 taxa; 23 (55%) were uncultivated phylotypes, of which seven were unique to endodontic infections. Clone sequencing and terminal restriction fragment length polymorphism analysis revealed that the most commonly detected taxa were Fusobacterium nucleatum (including terminal restriction fragment types 1 and 2), Peptostreptococcus micros/Peptostreptococcus sp. oral clone AJ062/BS044/FG014, Prevotella species, Dialister species, Mogibacterium species, Lachnospiraceae oral clone 55A-34, Filifactor alocis, Megasphaera sp. oral clone CS025/BS073, and Veillonella sp. oral clone BP1-85/Veillonella dispar/V. parvula. Bacteroides-like sp. oral clone X083/Bacteroidales oral clone MCE7&#95;20 and Dialister sp. oral clone BS016/MCE7&#95;134 were detected only in asymptomatic teeth. On the other hand, F. nucleatum terminal restriction fragment type 2, Prevotella intermedia, Dialister pneumosintes, and some phylotypes were exclusively detected in symptomatic samples. Bacterial profiles of symptomatic endodontic infections generated by terminal restriction fragment length polymorphism analysis were clearly different from those of asymptomatic infections. Overall, the average number of terminal restriction fragments in symptomatic samples was significantly larger than in asymptomatic samples. Molecular analysis of the microbiota associated with symptomatic or asymptomatic endodontic infections indicates that the endodontic bacterial diversity is greater than previously described by culture methods and that the structure of the microbiota differ significantly between asymptomatic and symptomatic infections.

Levels of phenotypic and genotypic diversity among seven Megasphaera elsdenii strains recovered from rumen contents of cattle, sheep and lambs were determined by a combination of antibiotic-resistance analysis and PCR fingerprint techniques targeted both to the ribosomal RNA operon (ARDRA, RISA) and the whole genome (ERIC-PCR, RAPD-PCR). Despite exhibiting different antibiotic resistance profiles, the tested strains represent genetically nearly identical isolates. Close genetic relatedness was found among M. elsdenii isolates that originated from vastly different habitats worldwide, as revealed by the comparison of 16S rDNA sequences.