Myroides profundi sp. nov., isolated from deep-sea sediment of the southern Okinawa Trough

A Gram-negative, nonmotile, aerobic and oxidase- and catalase-positive bacterium, designated D25(T), was isolated from the deep-sea sediments of the southern Okinawa Trough area. Phylogenetic analyses of 16S rRNA gene sequences showed that strain D25(T) fell within the genus Myroides, with 99.2%, 96.0% and 93.4% sequence similarities to the only three recognized species of Myroides. However, the DNA-DNA similarity value between strain D25(T) and its nearest neighbour Myroides odoratimimus JCM 7460(T) was only 49.9% (<70%). Several phenotypic properties could be used to distinguish strain D25(T) from other Myroides species. The main cellular fatty acids of strain D25(T) were iso-C(15:0), iso-C(17:1)omega9c, iso-C(17:0)3-OH and Summed Feature 3 (comprising C(16:1)omega7c and/or iso-C(15:0)2-OH). The major respiratory quinone was MK-6. The DNA G+C content was 33.0 mol%. The results of the polyphasic taxonomy analysis suggested that strain D25(T) represents a novel species of the genus Myroides, for which the name Myroides profundi sp. nov. is proposed. The type strain is D25(T) (=CCTCC M 208030(T)=DSM 19823(T)).     

<Emphasis Type="Italic">Myroides injenensis</Emphasis> sp. nov., a new member isolated from human urine

A Gram-negative, yellow-pigmented, rod-shaped bacteria, designated M09-0166^Tand M09-1053 were isolated from human urine samples. 16S rRNA gene sequence analysis revealed that the isolates belong to the Myroides cluster and were closely related to Myroides phaeus DSM 23313^T (96.3 %), Myroides odoratimimus KCTC 23053^T (96.1 %), Myroides profundi KCTC 23066^T (96.0 %), Myroides odoratus KCTC 23054^T (95.4 %) and Myroides pelagicus KCTC 12661^T (95.2 %). The major mena quinone was identified as MK-6. The major polar lipids were identified as phosphatidylethanolamine, amino lipids, and several unknown lipids, and the major fatty acids as iso-C_15:0 and iso-C_17:0 3-OH. Phenotypic and chemotaxonomic data supported the affiliation of the isolates with the genus Myroides and clearly indicated that two isolates represent novel species, for which the name Myroides injenensis sp. nov. (type strain, M09-0166^T = KCTC 23367^T = JCM 17451^T) is proposed.     

香味菌临床分离株耐药谱分析

目的回顾性分析本院临床分离的香味菌的药物敏感情况,指导临床合理使用抗生素。方法收集本院2012年1月至2013年12月期间临床分离的香味菌,采用法国生物梅里埃公司的全自动微生物分析仪VITEK-2进行菌株鉴定,以及VITEK-2配套药敏试验复合板进行药敏检测,分析其耐药谱。结果共收集了8株香味菌,且均呈现多重耐药谱。对头孢菌素类抗生素的耐药率很高,特别是对头孢唑林、头孢他啶、头孢曲松的耐药率均为100%。对氨曲南和呋喃妥因的耐药率均为100%。对碳青霉烯类抗生素亚胺培南的非敏感率达到87.5%。而耐药率最低的左旋氧氟沙星为37.5%。结论本院分离的香味菌呈现多重耐药谱,需对其耐药机制进一步研究。     

Potency of extract contents from selected tropical chewing sticks against Staphylococcus aureus and Staphylococcus auricularis

Two strains of enteropathogenic Gram-positive bacteria (Staphylococcus auricularis, NIAH 11484 and Staphylococcus aureus, IFO 12732) were tested in vitro for their resistance to extracts from tropical chewing stick species, namely, Garcinia mannii Heck, Masularia accuminata (G. Don) Benth, Zanthoxylum gilletii (DeWild) Waterman, Terminalia glaucescens Plauch ex Benth, Azadiracta indica A. Juss, Anogeissus leiocarpus Guill & Perr and Pseudocedrela kotschyi (Schweinf.). The chewing sticks are normally used for oral hygiene and this is felt to be related to their ability to attack bioagents that could invade the mouth during normal nutrition. Results from our study showed that the antibiotic properties of test chewing stick species vary and are target-microbe-specific. Of the species examined, only T. glaucescens showed appreciable broad antibiotic effect against S. aureus and S. auricularis. Intense antibiotic activity against S. aureus occurred when using a 2.0 g/l extract concentration and a 30-h incubation. T. glaucescens also showed intense activity against S. auricularis at 2.0 g/l concentration, 30-h incubation when all other extracts had lost their potency. A. indica is, however, most effective against S. aureus, showing appreciable antibiotic activity at 0.4 g/l concentration, 30-h incubation. Z. gilletii has no antibiotic activity against any of the test bacteria. The antistaphylococcus compounds in T. glaucescens and A. indica are worthy of isolation and further analyses.     

Potency of extract contents from selected tropical chewing sticks against Staphylococcus aureus and Staphylococcus auricularis

Two strains of enteropathogenic Gram-positive bacteria (Staphylococcus auricularis, NIAH 11484 and Staphylococcus aureus, IFO 12732) were tested in vitro for their resistance to extracts from tropical chewing stick species, namely, Garcinia mannii Heck, Masularia accuminata (G. Don) Benth, Zanthoxylum gilletii (DeWild) Waterman, Terminalia glaucescens Plauch ex Benth, Azadiracta indica A. Juss, Anogeissus leiocarpus Guill & Perr and Pseudocedrela kotschyi (Schweinf.). The chewing sticks are normally used for oral hygiene and this is felt to be related to their ability to attack bioagents that could invade the mouth during normal nutrition. Results from our study showed that the antibiotic properties of test chewing stick species vary and are target-microbe-specific. Of the species examined, only T. glaucescens showed appreciable broad antibiotic effect against S. aureus and S. auricularis. Intense antibiotic activity against S. aureus occurred when using a 2.0 g/l extract concentration and a 30-h incubation. T. glaucescens also showed intense activity against S. auricularis at 2.0 g/l concentration, 30-h incubation when all other extracts had lost their potency. A. indica is, however, most effective against S. aureus, showing appreciable antibiotic activity at 0.4 g/l concentration, 30-h incubation. Z. gilletii has no antibiotic activity against any of the test bacteria. The antistaphylococcus compounds in T. glaucescens and A. indica are worthy of isolation and further analyses.     

Multiple antibiotic resistance indexing of coliforms to identify high risk contamination sites in aquatic environment

Bacteriological analysis of the water samples collected from upstream, midstream and downstream points along the bank of the river revealed high populations of Escherichia coli, Citrobacter freundii, Citrobacter diversus, Enterobacter aerogens and Klebsiella species. All these isolates were screened against eight antibiotics to determine the prevalence of multiple antibiotic resistance among isolates at different sites of the river. The study revealed that multiple antibiotic resistance was prominently seen in coliforms at downstream sites (Average multiple antibiotic resistance index, MAR Index = 0.43) while it was low in coliforms at upstream sites (MAR Index = 0.15). These differences in MAR indices provide a method for distinguishing high risk contamination sites in aquatic environment.     

Pseudomonas aeruginosa tssC1 links type VI secretion and biofilm-specific antibiotic resistance

Biofilm-specific antibiotic resistance is influenced by multiple factors. We demonstrated that Pseudomonas aeruginosa tssC1, a gene implicated in type VI secretion (T6S), is important for resistance of biofilms to a subset of antibiotics. We showed that tssC1 expression is induced in biofilms and confirmed that tssC1 is required for T6S.     

Relationship between plasmid occurrence and antibiotic resistance in Myroides odoratimimus SKS05-GRD isolated from raw chicken meat

Fifteen flavobacterium strains were isolated from raw chicken meat, raw goat meat and poultry soil in Coimbatore, Tamil Nadu. Most of the isolates developed yellow pigmented colonies with mucoid-spreading edges on food flavobacterium medium. The flavobacteria were Gram-negative rods and failed to produce indole and were non-fermentative. Moreover, they produced a rich array of enzymes such as amylase, lipase, catalase, urease, gelatinase, DNase, and oxidase. Phylogenetic analyses of the strain SKS05-GRD based on 16S rRNA gene sequences revealed the bacterium as Myroides odoratimimus (nucleotide sequence accession number JQ178355). Antimicrobial susceptibility test for M. odoratimimus SKS05-GRD and other strains were assessed by disc diffusion method. M. odoratimimus SKS05-GRD showed wide resistance to the antibiotics such as amikacin, ampicillin, cefadroxil, cefoperazone, ceftazidine, ceftriaxone, netillin and gentamicin. M. odoratimimus was subjected to plasmid isolation and plasmid curing to seek the relationship between plasmid and antibiotic resistance. Plasmid curing was done by using ethidium bromide and was found to be effective at 300 and 500 μg/ml. Assessment of antibiotic sensitivity of M. odoratimimus SKS05-GRD showed sensitivity to amikacin, gentamicin and kanamycin confirming that resistance to these three antibiotics is plasmid mediated and other antibiotic resistance are chromosomal mediated.     

Aeromonas tecta sp. nov., isolated from clinical and environmental sources

Five Aeromonas strains, isolated from both clinical and environmental sources and characterized by a polyphasic approach, including phylogenetic analysis derived from gyrB, rpoD, and 16S rRNA gene sequencing, as well as DNA-DNA hybridization, extensive biochemical and antibiotic susceptibility tests, were recognized as members of an unknown, or undescribed, Aeromonas species. These "Aeromonas eucrenophila-like" strains were closely related to the species A. eucrenophila and Aeromonas encheleia, but they were negative for indole and acid from glycerol tests. Therefore, based on the results of the phylogenetic analyses and DNA-DNA pairing data of these strains, a novel species of the genus Aeromonas is described, for which the name Aeromonas tecta is proposed with isolate F518(T) (CECT7082(T), DSM17300(T), MDC91(T)) as the type strain.     

Variations in antibiotic resistance profile in Enterobacteriaceae isolated from wild Australian mammals

We carried out a retrospective analysis of 946 strains of Enterobacteriaceae isolated from wild Australian mammals between 1993 and 1997. The prevalence of resistance to fixed concentrations of 32 antimicrobial agents was determined, and the respective roles that taxonomic family of the host, state of origin and bacterial species play in defining prevalence and range of resistance were investigated. Our results demonstrated a low but widespread prevalence of antimicrobial resistance in wild isolates. Only amikacin, ciprofloxacin, meropenem and gentamicin inhibited growth in all 946 samples. There was extensive variation in the combination of antibiotics to which isolates were resistant, and multiple antibiotic resistance was common. Geographical location and host group significantly influenced the antibiotic resistance profile of an isolate, whereas bacterial species influenced both the resistance profile of an isolate and the number of antibiotics it was resistant to. The role of these factors in determining observed antibiotic resistance profiles suggests that any study measuring resistance in wild isolates should include the broadest possible range of bacterial species, host species and sampling locations. As such, this study provides an important new baseline for future measurements of antibiotic resistance in the Australian environment.     

The incidence of Weeksella- and Bergeyella-like bacteria in the food environment

Eighty-five catalase- and oxidase-positive Gram-negative rods and cocci susceptible to penicillin G were isolated from a variety of food sources. The phenotypic relationships of these isolates with reference cultures of Bergeyella -like, Chryseobacterium, Empedobacter, Myroides , Moraxella , Sphingobacterium and Weeksella -like strains were examined by numerical taxonomy. Seventy-three isolates were recovered in five groups; 80% of the isolates clustered in groups 1, 2 and 3 and produced indole, bearing a strong resemblance to Weeksella and Bergeyella . They could not, however, be regarded as belonging to the known species of W. virosa and B. zoohelcum . It is suggested that three species may be necessary to accommodate the environmental Weeksella - or Bergeyella -like bacteria. The isolates in groups 4 and 5 had white colonies and were unable to produce indole, in this way resembling the Moraxella genus.     

Temporin/VesCP (T/V)-like antibiotic peptides, derived from frogs and wasps, induce migration of human monocytes and neutrophils

Summary  Several naturally occurring antimicrobial peptides, from mammals and insects, have previously been shown to be chemotactic for human inflammatory cells. Based on this evidence, ten synthetic analogs of naturally occurring antibiotic peptides from the skin secretions of three species of Ranid frogs and the venom of one species of Vespid wasp (i.e., T/V-like peptides) were tested for their abilities to induce migration of human neutrophils and monocytes. These included temporin A (TA fromRana temporaria), temporin 1P (T1P fromR. pipens), ranateurin 6 (Rana-6 fromR. catesbeiana)], three TA analogs [all D-amino acids (D-TA), reversed sequence (Rev-TA), and Pro3→Gly (G3-TA)], two frog skin-related T/V-like peptide consensus sequences (I4S10-Con and I4G10-Con), VesCP-M (VCP-M fromVespa mandarinia), and a hybrid peptide composed of portions of the insect antibiotic peptide, cecropin A (CA), and TA (CATA). TA, T1P, Rana-6, VCP-M, G3-TA, I4S10-Con, I4G10-Con, and CATA all induced cell migration at micromolar concentrations. D-TA and Rev-TA did not induce cell migration, suggesting that this process involves a chiral interaction, such as receptor binding, and also depends on the order of amino acids within TA. The results demonstrate, for the first time, that certain T/V-like antibiotic peptides are capable of inducing chemotaxis of human phagocytes and suggest that these peptides are multifunctional molecules with antimicrobial, hemolytic, and chemotactic capabilities.     

Temporin/VesCP (T/V)-like antibiotic peptides,derived from frogs and wasps,induce migration of human monocytes and neutrophils

Summary Several naturally occurring antimicrobial peptides, from mammals and insects, have previously been shown to be chemotactic for human inflammatory cells. Based on this evidence, ten synthetic analogs of naturally occurring antibiotic peptides from the skin secretions of three species of Ranid frogs and the venom of one species of Vespid wasp (i.e., T/V-like peptides) were tested for their abilities to induce migration of human neutrophils and monocytes. These included temporin A (TA fromRana temporaria), temporin 1P (T1P fromR. pipens), ranateurin 6 (Rana-6 fromR. catesbeiana)], three TA analogs [all D-amino acids (D-TA), reversed sequence (Rev-TA), and Pro3→Gly (G3-TA)], two frog skin-related T/V-like peptide consensus sequences (I4S10-Con and I4G10-Con), VesCP-M (VCP-M fromVespa mandarinia), and a hybrid peptide composed of portions of the insect antibiotic peptide, cecropin A (CA), and TA (CATA). TA, T1P, Rana-6, VCP-M, G3-TA, I4S10-Con, I4G10-Con, and CATA all induced cell migration at micromolar concentrations. D-TA and Rev-TA did not induce cell migration, suggesting that this process involves a chiral interaction, such as receptor binding, and also depends on the order of amino acids within TA. The results demonstrate, for the first time, that certain T/V-like antibiotic peptides are capable of inducing chemotaxis of human phagocytes and suggest that these peptides are multifunctional molecules with antimicrobial, hemolytic, and chemotactic capabilities.     

The use of ribotyping and antibiotic resistance patterns for identification of host sources of Escherichia coli strains

AIMS: To compare antibiotic resistance and ribotyping patterns ability to identify triplicate isolates sent from a group of 40 Escherichia coli taken from seven host sources. METHODS AND RESULTS: Of the 120 isolates, 22 isolates were resistant to ampicillin, streptomycin, tetracycline and trimethoprim and 98 isolates were susceptible. Antibiotic patterns identified 33 of the triplicates and three of the six groups had isolates from multiple hosts. Ribotyping divided the isolates into 27 ribotype groups with all triplicates grouped into the same ribotype group with one host per group. CONCLUSIONS: Antibiotic susceptibility pattern placed 98 of the isolates in a single group with 50% of the antibiotic susceptibility pattern groups containing multiple host species. Ribotyping groups were host specific with each host having one to seven ribotype groups. SIGNIFICANCE AND IMPACT OF THE STUDY: Antibiotic susceptibility pattern groups have been used for environmental source identification and faecal pollution tracking, however these groups do not always distinguish between host species. Stability of the markers is a potential concern and this system can only be used if antibiotic resistance levels are high in the isolates studied. All isolates have a ribotype group which was stable and like other molecular methods has advantages over antibiotic susceptibility pattern groups which uses a phenotypic method.     

Bacterial resistance evolution by recruitment of super-integron gene cassettes

The capture and spread of antibiotic resistance determinants by integrons underlies the rapid evolution of multiple antibiotic resistance among diverse Gram-negative clinical isolates. The association of multiple resistance integrons (MRIs) with mobile DNA elements facilitates their transit across phylogenetic boundaries and augments the potential impact of integrons on bacterial evolution. Recently, ancestral chromosomal versions, the super-integrons (SIs), were found to be genuine components of the genomes of diverse bacterial species. SIs possess evolutionary characteristics and stockpiles of adaptive functions, including cassettes related to antibiotic resistance determinants previously characterized in clinical isolates, which suggest that MRIs and their resistance genes were originally recruited from SIs and their pool of amassed genes. However, the recombination activity of integrons has never been demonstrated in a bacterium other than Escherichia coli. We introduced a naturally occurring MRI (TpR, SulR) on a conjugative plasmid into Vibrio cholerae, a species known to harbour a SI. We show that MRIs can randomly recruit genes directly from the cache of SI cassettes. By applying a selective constraint for the development of antibiotic resistance, we demonstrate bacterial resistance evolution through the recruitment a novel, but phenotypically silent, chloramphenicol acetyltransferase gene from the V. cholerae SI and its precise insertion into the MRI. The resulting resistance profile (CmR, TpR, SulR) could then be disseminated by conjugation to other clinically relevant pathogens at high frequency. These results demonstrate that otherwise phenotypically sensitive strains may still be a genetic source for the evolution of resistance to clinically relevant antibiotics through integron-mediated recombination events.     

The horizontal flow of the plasmid resistome: clues from inter‐generic similarity networks

By integrating sequence similarity data of plasmid‐encoded antibiotic resistance determinants with those coming from a less transferred molecular marker, we constructed a network in which all the sequences that most likely underwent horizontal gene transfer (HGT) were linked together. The analysis of this network revealed that either geographical barriers or taxonomical distance can often be overcome since phylogenetically unrelated bacteria, and/or those inhabiting distinct environments, were found to share common antibiotic resistance determinants, probably as a result of (one or multiple) HGT event(s). Data obtained also revealed that bacteria viable through multiple environments (ubiquitous) are likely to give a crucial contribution to the spreading of bacterial resistance towards antimicrobial compounds. These analyses represent a first attempt to give an almost global picture of the horizontal flow of antibiotic resistance determinants at the whole bacterial community level, also underlining the power of HGT among bacteria and how this ‘horizontal flow’ is poorly affected by both taxonomy and physical distance. Finally, data presented may be useful in the infections control procedures, suggesting which bacterial species are more likely acting as vectors of antibiotic resistance determinants.     

Isolation and identification of methylobacterium species from the tap water in hospitals in Japan and their antibiotic susceptibility

Contamination of tap water by Methylobacterium species has become a serious concern in hospitals. This study was planned to examine the distribution of Methylobacterium species inhabiting tap water used in Japanese hospitals and antibiotic sensitivity of the isolates in 2004. Species identification of 58 isolates was performed based on the homology of a partial sequence of 16S rDNA. The dominant Methylobacterium species in hospital water were M. aquaticum and M. fujisawaense. To examine the biochemical properties of these isolates, a carbon source utilization was tested using an API50CH kit. The phenotypic character varied widely, and was not necessarily consistent with the results of phylogenic analysis based on the partial 16S rDNA sequence, suggesting that the biochemical properties are not suitable for identification of Methylobacterium species. The isolates were also subjected to antibiotic sensitivity tests. They were resistant to 8 antibiotics, but highly sensitive to imipenem (MIC90 = 1 microg/ml) and tetracycline (MIC90 = 8 microg/ml). These findings concerning the isolates revealed the presence of Methylobacterium species with resistance to multiple antibiotics in hospital tap water.     

水环境中耐药菌污染与危害研究进展

细菌在抗菌药选择性压力下产生耐药性并可传代,通过质粒和整合子等可移动基因元件将耐药基因在相同或不同种属中广泛传播,导致细菌多重耐药,并可通过多种途径进入水体,水环境日益成为庞大的耐药基因库,为致病菌及条件致病菌提供获得大量耐药基因的机会,若多重耐药菌再次侵入人体,可能引发严重的公共卫生问题。