Klebsiella oxytoca Complex: Update on Taxonomy, Antimicrobial Resistance, and Virulence

Author(s):  
Jing Yang ◽  
Haiyan Long ◽  
Ya Hu ◽  
Yu Feng ◽  
Alan McNally ◽  
...  

Klebsiella oxytoca is actually a complex of nine species— Klebsiella grimontii , Klebsiella huaxiensis , Klebsiella michiganensis , K. oxytoca , Klebsiella pasteurii , Klebsiella spallanzanii , and three unnamed novel species. Phenotypic tests can assign isolates to the complex, but precise species identification requires genome-based analysis.

2017 ◽  
Vol 84 (2) ◽  
Author(s):  
Roman Pantůček ◽  
Ivo Sedláček ◽  
Adéla Indráková ◽  
Veronika Vrbovská ◽  
Ivana Mašlaňová ◽  
...  

ABSTRACT Two Gram-stain-positive, coagulase-negative staphylococcal strains were isolated from abiotic sources comprising stone fragments and sandy soil in James Ross Island, Antarctica. Here, we describe properties of a novel species of the genus Staphylococcus that has a 16S rRNA gene sequence nearly identical to that of Staphylococcus saprophyticus. However, compared to S. saprophyticus and the next closest relatives, the new species demonstrates considerable phylogenetic distance at the whole-genome level, with an average nucleotide identity of <85% and inferred DNA-DNA hybridization of <30%. It forms a separate branch in the S. saprophyticus phylogenetic clade as confirmed by multilocus sequence analysis of six housekeeping genes, rpoB, hsp60, tuf, dnaJ, gap, and sod. Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) and key biochemical characteristics allowed these bacteria to be distinguished from their nearest phylogenetic neighbors. In contrast to S. saprophyticus subsp. saprophyticus, the novel strains are pyrrolidonyl arylamidase and β-glucuronidase positive and β-galactosidase negative, nitrate is reduced, and acid produced aerobically from d-mannose. Whole-genome sequencing of the 2.69-Mb large chromosome revealed the presence of a number of mobile genetic elements, including the 27-kb pseudo-staphylococcus cassette chromosome mec of strain P5085T (ψSCCmec P5085), harboring the mecC gene, two composite phage-inducible chromosomal islands probably essential to adaptation to extreme environments, and one complete and one defective prophage. Both strains are resistant to penicillin G, ampicillin, ceftazidime, methicillin, cefoxitin, and fosfomycin. We hypothesize that antibiotic resistance might represent an evolutionary advantage against beta-lactam producers, which are common in a polar environment. Based on these results, a novel species of the genus Staphylococcus is described and named Staphylococcus edaphicus sp. nov. The type strain is P5085T (= CCM 8730T = DSM 104441T). IMPORTANCE The description of Staphylococcus edaphicus sp. nov. enables the comparison of multidrug-resistant staphylococci from human and veterinary sources evolved in the globalized world to their geographically distant relative from the extreme Antarctic environment. Although this new species was not exposed to the pressure of antibiotic treatment in human or veterinary practice, mobile genetic elements carrying antimicrobial resistance genes were found in the genome. The genomic characteristics presented here elucidate the evolutionary relationships in the Staphylococcus genus with a special focus on antimicrobial resistance, pathogenicity, and survival traits. Genes encoded on mobile genetic elements were arranged in unique combinations but retained conserved locations for the integration of mobile genetic elements. These findings point to enormous plasticity of the staphylococcal pangenome, shaped by horizontal gene transfer. Thus, S. edaphicus can act not only as a reservoir of antibiotic resistance in a natural environment but also as a mediator for the spread and evolution of resistance genes.


2018 ◽  
Vol 56 (9) ◽  
Author(s):  
Valentina Donà ◽  
Joost H. Smid ◽  
Sara Kasraian ◽  
Dianne Egli-Gany ◽  
Ferah Dost ◽  
...  

ABSTRACT Molecular methods are often used for Neisseria gonorrhoeae detection, but complete definition of antimicrobial resistance (AMR) patterns still requires phenotypic tests. We developed an assay that both identifies N. gonorrhoeae and detects AMR determinants in clinical specimens. We designed a mismatch amplification mutation assay (MAMA)-based SYBR green real-time PCR targeting one N. gonorrhoeae-specific region (opa); mosaic penA alleles (Asp345 deletion [Asp345del], Gly545Ser) associated with decreased susceptibility to cephalosporins; and alterations conferring resistance to ciprofloxacin (GyrA Ser91Phe), azithromycin (23S rRNA A2059G and C2611T), and spectinomycin (16S rRNA C1192T). We applied the real-time PCR to 489 clinical specimens, of which 94 had paired culture isolates, and evaluated its performance by comparison with the performance of commercial diagnostic molecular and phenotypic tests. Our assay exhibited a sensitivity/specificity of 93%/100%, 96%/85%, 90%/91%, 100%/100%, and 100%/90% for the detection of N. gonorrhoeae directly from urethral, rectal, pharyngeal, cervical, and vaginal samples, respectively. The MAMA strategy allowed the detection of AMR mutations by comparing cycle threshold values with the results of the reference opa reaction. The method accurately predicted the phenotype of resistance to four antibiotic classes, as determined by comparison with the MIC values obtained from 94 paired cultures (sensitivity/specificity for cephalosporins, azithromycin, ciprofloxacin, and spectinomycin resistance, 100%/95%, 100%/100%, 100%/100%, and not applicable [NA]/100%, respectively, in genital specimens and NA/72%, NA/98%, 100%/97%, and NA/96%, respectively, in extragenital specimens). False-positive results, particularly for the penA Asp345del reaction, were observed predominantly in pharyngeal specimens. Our real-time PCR assay is a promising rapid method to identify N. gonorrhoeae and predict AMR directly in genital specimens, but further optimization for extragenital specimens is needed.


2016 ◽  
Vol 54 (3) ◽  
pp. 687-698 ◽  
Author(s):  
Hossein Salimnia ◽  
Marilynn R. Fairfax ◽  
Paul R. Lephart ◽  
Paul Schreckenberger ◽  
Sharon M. DesJarlais ◽  
...  

Sepsis is a major cause of morbidity, mortality, and increased medical expense. Rapid diagnosis improves outcomes and reduces costs. The FilmArray blood culture identification panel (BioFire Diagnostics LLC, Salt Lake City, UT), a highly multiplexed PCR assay, can identify 24 etiologic agents of sepsis (8 Gram-positive, 11 Gram-negative, and 5 yeast species) and three antimicrobial resistance genes (mecA,vanA/B, andblaKPC) from positive blood culture bottles. It provides results in about 1 h with 2 min for assay setup. We present the results of an eight-center trial comparing the sensitivity and specificity of the panel with those of the laboratories' standard phenotypic identification techniques, as well as with molecular methods used to distinguishAcinetobacter baumanniifrom other members of theA. calcoaceticus-A. baumanniicomplex and to detect antimicrobial resistance genes. Testing included 2,207 positive aerobic blood culture samples, 1,568 clinical and 639 seeded. Samples were tested fresh or were frozen for later testing within 8 h after the bottles were flagged as positive by an automated blood culture system. At least one organism was detected by the panel in 1,382 (88.1%) of the positive clinical specimens. The others contained primarily off-panel organisms. The panel reported multiple organisms in 81 (5.86%) positive clinical specimens. The unresolved blood culture identification sensitivity for all target detections exceeded 96%, except forKlebsiella oxytoca(92.2%), which achieved 98.3% sensitivity after resolution of an unavoidable phenotypic error. The sensitivity and specificity forvanA/BandblaKPCwere 100%; those formecAwere 98.4 and 98.3%, respectively.


2013 ◽  
Vol 57 (7) ◽  
pp. 2981-2988 ◽  
Author(s):  
Wang-Huei Sheng ◽  
Robert E. Badal ◽  
Po-Ren Hsueh

ABSTRACTThe increasing trend of β-lactam resistance amongEnterobacteriaceaeis a worldwide threat.Enterobacteriaceaeisolates causing intra-abdominal infections (IAI) from the Study for Monitoring Antimicrobial Resistance Trends (SMART) collected in 2008 and 2009 from the Asia-Pacific region were investigated. Detection of extended-spectrum β-lactamases (ESBLs), AmpC β-lactamases, and carbapenemases was performed by multiplex PCR. A total of 699Enterobacteriaceaeisolates with positive genotypic results, includedEscherichia coli(n= 443),Klebsiella pneumoniae(n= 187),Enterobacter cloacae(n= 45),Klebsiella oxytoca(n= 9),Citrobacter freundii(n= 5),Proteus mirabilis(n= 3),Enterobacter aerogenes(n= 2),Morganella morganii(n= 2), and one each ofEnterobacter asburiae,Proteus vulgaris, andProvidencia rettgeriwere analyzed. Nearly 20% of these β-lactamase-producingEnterobacteriaceaeisolates were from community-associated IAI. CTX-M (588 isolates, including 428 [72.8%] with CTX-M-15) was the most common ESBL, followed by SHV (n= 59) and TEM (n= 4). CMY (n= 110, including 102 [92.7%] with CMY-2) was the most common AmpC β-lactamase, followed by DHA (n= 46) and ACT/MIR (n= 40). NDM (n= 65, including 62 [95.4%] with NDM-1) was the most common carbapenemase, followed by IMP (n= 7) and OXA (n= 7). Isolates from hospital-associated IAI had more complicated β-lactamase combinations than isolates from the community. Carbapenemases were all exclusively detected inEnterobacteriaceaeisolates from India, except that IMP β-lactamases were also detected in Philippines and Australia. CTX-M β-lactamases were the predominant ESBLs produced byEnterobacteriaceaecausing IAI in the Asia-Pacific region. Emergence of CTX-M-15-, CMY-2-, and NDM-1-producingEnterobacteriaceaeisolates is of major concern and highlights the need for further surveillance in this area.


mSystems ◽  
2020 ◽  
Vol 5 (4) ◽  
Author(s):  
Wenjing Wu ◽  
Yu Feng ◽  
Zhiyong Zong

ABSTRACT The genus Enterobacter comprises common pathogens and has a complicated taxonomy. Precise taxonomic assignation lays a foundation for microbiology. In this study, we updated the Enterobacter taxonomy based on robust genome analyses. We found that all Enterobacter subspecies assignments were incorrect. Enterobacter cloacae subsp. dissolvens and Enterobacter hormaechei subsp. hoffmannii are species (Enterobacter dissolvens and Enterobacter hoffmannii, respectively) rather than subspecies. Enterobacter xiangfangensis, Enterobacter hormaechei subsp. oharae, and Enterobacter hormaechei subsp. steigerwaltii are not Enterobacter hormaechei subspecies but belong to the same species (Enterobacter xiangfangensis). Enterobacter timonensis should be removed to Pseudenterobacter, a novel genus. We then reported two novel species, Enterobacter quasiroggenkampii and Enterobacter quasimori, by genome- and phenotype-based characterization. We also applied the updated taxonomy to curate 1,997 Enterobacter genomes in GenBank. Species identification was changed following our updated taxonomy for the majority of publicly available strains (1,542, 77.2%). The most common Enterobacter species was E. xiangfangensis. We identified 14 novel tentative Enterobacter genomospecies. This study highlights that updated and curated taxonomic assignments are the premise of correct identification. IMPORTANCE Enterobacter species are major human pathogens. Precise species identification lays a foundation for microbiology, but the taxonomy of Enterobacter is complicated and confusing. In this study, first, we significantly updated the taxonomy of Enterobacter by rigorous genome analyses and found that all subspecies assignments of Enterobacter were incorrect. Second, we characterized and reported two novel Enterobacter species with clinical significance. Third, we curated 1,997 Enterobacter genome sequences deposited in GenBank and found that the species identification of most Enterobacter strains needed to be corrected. Fourth, we found that the most common Enterobacter species seen in clinical samples is Enterobacter xiangfangensis rather than Enterobacter cloacae. Fifth, we identified 14 tentative novel Enterobacter and 18 tentative novel non-Enterobacter species. This study highlights that updated and curated taxonomic assignments are the premise of correct species identification. We recommend that future Enterobacter studies need to use the updated taxonomy to avoid misleading information.


2017 ◽  
Vol 61 (5) ◽  
Author(s):  
Clara Sinel ◽  
Margherita Cacaci ◽  
Pierrick Meignen ◽  
François Guérin ◽  
Bryan W. Davies ◽  
...  

ABSTRACT Enterococcus faecium has emerged as a major opportunistic pathogen for 2 decades with the spread of hospital-adapted multidrug-resistant clones. As members of the intestinal microbiota, they are subjected to numerous bacterial stresses, including antibiotics at subinhibitory concentrations (SICs). Since fluoroquinolones are extensively prescribed, SICs are very likely to occur in vivo, with potential effects on bacterial metabolism with subsequent modulation of opportunistic traits. The aim of this study was to evaluate globally the impact of SICs of ciprofloxacin on antimicrobial resistance and pathogenicity of E. faecium. Transcriptomic analysis was performed by RNA sequencing (RNA-seq) (HiSeq 2500; Illumina) using the vanB-positive reference strain E. faecium Aus0004 in the absence or presence of ciprofloxacin SIC (0.38 mg/liter, i.e., 1/8 of the MIC). Several genetic and phenotypic tests were used for validation. In the presence of ciprofloxacin SIC, 196 genes were significantly induced, whereas 286 genes were significantly repressed, meaning that 16.8% of the E. faecium genome was altered. Among upregulated genes, EFAU004_02294 (fold change, 14.3) encoded a protein (Qnr of E. faecium [EfmQnr]) homologue of Qnr proteins involved in quinolone resistance in Gram-negative bacilli. Its implication in intrinsic and adaptive fluoroquinolone (FQ) resistance in E. faecium was experimentally ascertained. Moreover, EFAU004_02292, coding for the collagen adhesin Acm, was also induced by the SIC of ciprofloxacin (fold change, 8.2), and higher adhesion capabilities were demonstrated phenotypically. Both EfmQnr and Acm determinants may play an important role in the transition from a commensal to a pathogenic state of E. faecium that resides in the gut of patients receiving fluoroquinolone therapy.


2020 ◽  
Vol 70 (5) ◽  
pp. 3278-3286 ◽  
Author(s):  
Sukriti Gujarati ◽  
Diptaraj Chaudhari ◽  
Ashwini Hagir ◽  
Mitesh Khairnar ◽  
Yogesh Shouche ◽  
...  

A novel bacterial strain, designated TOUT106T, was isolated from the surface of a tomato. The cells were rod-shaped, Gram-negative, encapsulated and non-motile. Strain TOUT106T grows best at 28 °C and pH 7.0 and can tolerate up to 2 % (w/v) NaCl. Based on 16S rRNA gene phylogeny, strain TOUT106T was placed close to the Salmonella clade, with close similarity to Salmonella enterica subsp. arizonae strain NCTC 8297T (98.42 %). Results of genome-based phylogenetic analysis revealed that strain TOUT106T is placed well in the Klebsiella–Raoultella clade, by forming a distinct branch with Klebsiella michiganensis DSM25444T, Klebsiella oxytoca NCTC132727T, Klebsiella grimontii 06D021T and Klebsiella pasteurii SB6412T. The genomic DNA G+C content of strain TOUT106T is 53.53 mol%. The average nucleotide identity values of TOUT106T were less than 86.5 % with closely related members of the family Enterobacteriaceae . The major fatty acids of strain TOUT106T were C16 : 0, C17:0 cyclo, C14:0 3OH/C16:1 iso, C14 : 0, C19:0 cyclo ω8c, C18:1 ω6c/C18:1 ω7c, C12 : 0 and C16:1 ω7c/C16:1 ω6c. Strain TOUT106T showed differences in physiological, phenotypic and protein profiles by MALDI-TOF MS compared to its closest relatives. Based on the results of phenotypic, chemotaxonomic and phylogenetic analyses, strain TOUT106T could be distinguished from the recognized species of the genus Klebsiella . It is suggested to represent a novel species of this genus, for which the name Klebsiella indica sp. nov. is proposed. The type strain is TOUT106T (=MCC 2901T=KACC 21384T=JCM 33718T).


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Adam Goodwin ◽  
Sanket Padmanabhan ◽  
Sanchit Hira ◽  
Margaret Glancey ◽  
Monet Slinowsky ◽  
...  

AbstractWith over 3500 mosquito species described, accurate species identification of the few implicated in disease transmission is critical to mosquito borne disease mitigation. Yet this task is hindered by limited global taxonomic expertise and specimen damage consistent across common capture methods. Convolutional neural networks (CNNs) are promising with limited sets of species, but image database requirements restrict practical implementation. Using an image database of 2696 specimens from 67 mosquito species, we address the practical open-set problem with a detection algorithm for novel species. Closed-set classification of 16 known species achieved 97.04 ± 0.87% accuracy independently, and 89.07 ± 5.58% when cascaded with novelty detection. Closed-set classification of 39 species produces a macro F1-score of 86.07 ± 1.81%. This demonstrates an accurate, scalable, and practical computer vision solution to identify wild-caught mosquitoes for implementation in biosurveillance and targeted vector control programs, without the need for extensive image database development for each new target region.


2013 ◽  
Vol 63 (Pt_2) ◽  
pp. 458-463 ◽  
Author(s):  
Sonia R. Vartoukian ◽  
Julia Downes ◽  
Richard M. Palmer ◽  
William G. Wade

SGP1T, a strain belonging to a lineage of the phylum Synergistetes with no previously cultivated representatives was subjected to a comprehensive range of phenotypic and genotypic tests. For good growth the strain was dependent on co-culture with, or extracts from, selected other oral bacteria. Cells of strain SGP1T were asaccharolytic and major amounts of acetic acid and moderate amounts of propionic acid were produced as end products of metabolism in peptone-yeast extract-glucose broth supplemented with a filtered cell sonicate of Fusobacterium nucleatum subsp. nucleatum ATCC 25586T (25 %, v/v). Hydrogen sulphide was produced and gelatin was weakly hydrolysed. The major cellular fatty acids were C14 : 0, C18 : 0 and C16 : 0. The DNA G+C content of strain SGP1T was 63 mol%. Phylogenetic analysis of the full-length 16S rRNA gene showed that strain SGP1T represented a novel group within the phylum Synergistetes . A novel species in a new genus, Fretibacterium fastidiosum gen. nov., sp. nov., is proposed. The type strain of Fretibacterium fastidiosum is SGP1T ( = DSM 25557T = JCM 16858T).


2017 ◽  
Vol 61 (6) ◽  
Author(s):  
Julia V. Bugrysheva ◽  
David Sue ◽  
Jay E. Gee ◽  
Mindy G. Elrod ◽  
Alex R. Hoffmaster ◽  
...  

ABSTRACT Burkholderia pseudomallei Bp1651 is resistant to several classes of antibiotics that are usually effective for treatment of melioidosis, including tetracyclines, sulfonamides, and β-lactams such as penicillins (amoxicillin-clavulanic acid), cephalosporins (ceftazidime), and carbapenems (imipenem and meropenem). We sequenced, assembled, and annotated the Bp1651 genome and analyzed the sequence using comparative genomic analyses with susceptible strains, keyword searches of the annotation, publicly available antimicrobial resistance prediction tools, and published reports. More than 100 genes in the Bp1651 sequence were identified as potentially contributing to antimicrobial resistance. Most notably, we identified three previously uncharacterized point mutations in penA, which codes for a class A β-lactamase and was previously implicated in resistance to β-lactam antibiotics. The mutations result in amino acid changes T147A, D240G, and V261I. When individually introduced into select agent-excluded B. pseudomallei strain Bp82, D240G was found to contribute to ceftazidime resistance and T147A contributed to amoxicillin-clavulanic acid and imipenem resistance. This study provides the first evidence that mutations in penA may alter susceptibility to carbapenems in B. pseudomallei. Another mutation of interest was a point mutation affecting the dihydrofolate reductase gene folA, which likely explains the trimethoprim resistance of this strain. Bp1651 was susceptible to aminoglycosides likely because of a frameshift in the amrB gene, the transporter subunit of the AmrAB-OprA efflux pump. These findings expand the role of penA to include resistance to carbapenems and may assist in the development of molecular diagnostics that predict antimicrobial resistance and provide guidance for treatment of melioidosis.


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