scholarly journals Comparative Genomic Analysis and Phenotypic Characterization of Bronchoscope-Associated Klebsiella aerogenes

2021 ◽  
Vol 70 (3) ◽  
pp. 409-412
Author(s):  
FANG HUANG ◽  
SHUANG LI ◽  
LAN LOU ◽  
JUNJUN MO ◽  
HAO XU
Keyword(s):  
Antimicrobial Agents ◽  
Genomic Analysis ◽  
Phenotypic Characterization ◽  
Comparative Genomic ◽  
Klebsiella Aerogenes ◽  
Clinical Procedures ◽  
First Time ◽  
Sequence Types ◽  
Level Resistance

Bronchoscopes have been linked to outbreaks of nosocomial infections. The phenotypic and genomic profiles of bronchoscope-associated Klebsiella aerogenes isolates are largely unknown. In this work, a total of 358 isolates and 13 isolates were recovered from samples after clinical procedures and samples after decontamination procedures, respectively, over the five months. Antimicrobial susceptibility testing found seven K. aerogenes isolates exhibiting a low-level resistance to antimicrobial agents. Among seven K. aerogenes isolates, we found five sequence types (STs) clustered into three main clades. Collectively, this study described for the first time the phenotypic and genomic characteristics of bronchoscope-associated K. aerogenes.

scholarly journals Phenotypic and genomic characterization of pneumococcus-like streptococci isolated from HIV-seropositive patients

Microbiology ◽  
2010 ◽  
Vol 156 (3) ◽  
pp. 838-848 ◽  
Author(s):  
Truls M. Leegaard ◽  
Hester J. Bootsma ◽  
Dominique A. Caugant ◽  
Marc J. Eleveld ◽  
Turid Mannsåker ◽  
...  
Keyword(s):  
Antimicrobial Agents ◽  
Phenotypic Characterization ◽  
Comparative Genomic ◽  
Rrna Gene ◽  
Upper Respiratory Tract ◽  
Viridans Streptococci ◽  
Close Relationship ◽  
Phenotypic Tests ◽  
Hiv Seropositive

Accurate differentiation between pneumococci and other viridans streptococci is essential given their differences in clinical significance. However, classical phenotypic tests are often inconclusive, and many examples of atypical reactions have been reported. In this study, we applied various phenotypic and genotypic methods to discriminate between a collection of 12 streptococci isolated from the upper respiratory tract of HIV-seropositive individuals in 1998 and 1999. Conventional phenotypic characterization initially classified these streptococci as Streptococcus pneumoniae, as they were all sensitive to optochin and were all bile soluble. However, they did not agglutinate with anti-pneumococcal capsular antibodies and were also far more resistant to antimicrobial agents than typeable pneumococci isolated in the same period. Genotypic characterization of these isolates and control isolates by both multilocus sequence analysis (MLSA) and comparative genomic hybridization (CGH) showed that only a single isolate was genetically considered to be a true S. pneumoniae isolate, and that the remaining 11 non-typable isolates were indeed distinct from true pneumococci. Of these, 10 most closely resembled a subgroup of Streptococcus mitis isolates genetically, while one strain was identified as a Streptococcus pseudopneumoniae isolate. CGH also showed that a considerable part of the proposed pneumococcal core genome, including many of the known pneumococcal virulence factors, was conserved in the non-typable isolates. Sequencing of part of the 16S rRNA gene and investigation for the presence of ply by PCR corroborated these results. In conclusion, our findings confirm the close relationship between streptococci of the Mitis group, and show that both MLSA and CGH enable pneumococci to be distinguished from other Mitis group streptococci.

scholarly journals Characterization of Bordetella Bronchiseptica Isolated from Rabbits in Fujian, China

2020 ◽  
Author(s):  
Jinxiang Wang ◽  
Shikun Sun ◽  
Yanfeng Chen ◽  
Dongjin Chen ◽  
Lei Sang ◽  
...  
Keyword(s):  
Respiratory Disease ◽  
Animal Species ◽  
Bordetella Bronchiseptica ◽  
Economic Losses ◽  
Fujian Province ◽  
Pcr Screening ◽  
Resistance Rates ◽  
First Time ◽  
Sequence Types

Abstract Background Bordetella bronchiseptica can infect many animal species, and is a potential zoonotic pathogen that can also infect humans. In rabbits, infection of B. bronchiseptica is associated with respiratory disease, which causes economic losses to the rabbit farming. Fujian Province is a traditional importance rabbit farming area in China. However, no literature about the epidemiology and characteristics of B. bronchiseptica in rabbits in Fujian Province has been reported.Results A total of 219 B. bronchiseptica isolates were recovered from the 833 lung samples of dead rabbits with respiratory disease. The 219 isolates were typed into 11 sequence types (STs) including 5 known STs (ST6, ST10, ST12, ST14 and ST33) and 6 new STs (ST88, ST89, ST90, ST91, ST92 and ST93) by using multi-locus sequence typing (MLST). Surprisingly, all the 219 isolates carried the 5 virulence genes of fhaB, prn, cyaA, dnt and bteA in the PCR screening. Moreover, the isolates resistance to cefixime, ceftizoxime, cefatriaxone and ampicillin were detected, and the resistance rates to the 4 kinds of drug were 33.33, 31.05, 11.87 and 3.20%, respectively.Conclusions In the present study, we showed for the first time that B. bronchiseptica is widespread in rabbits in Fujian Province, and that B. bronchiseptica is an important pathogen associating with respiratory disease in rabbits in Fujian Province. Moreover, it should be alert to the potential occurrence of transmission events between rabbits and humans because the B. bronchiseptica strain of ST12 that can infect humans were also isolated from rabbits in Fujian Province.

Molecular mechanisms driving the in vivo development of OXA-10-mediated resistance to ceftolozane/tazobactam and ceftazidime/avibactam during treatment of XDR Pseudomonas aeruginosa infections

2020 ◽  
Vol 76 (1) ◽  
pp. 91-100
Author(s):  
Jorge Arca-Suárez ◽  
Cristina Lasarte-Monterrubio ◽  
Bruno-Kotska Rodiño-Janeiro ◽  
Gabriel Cabot ◽  
Juan Carlos Vázquez-Ucha ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Molecular Mechanisms ◽  
Genomic Analysis ◽  
Resistance Mechanisms ◽  
Comparative Genomic ◽  
Development Of Resistance ◽  
Structural Impact ◽  
Genetic Context

Abstract Background The development of resistance to ceftolozane/tazobactam and ceftazidime/avibactam during treatment of Pseudomonas aeruginosa infections is concerning. Objectives Characterization of the mechanisms leading to the development of OXA-10-mediated resistance to ceftolozane/tazobactam and ceftazidime/avibactam during treatment of XDR P. aeruginosa infections. Methods Four paired ceftolozane/tazobactam- and ceftazidime/avibactam-susceptible/resistant isolates were evaluated. MICs were determined by broth microdilution. STs, resistance mechanisms and genetic context of β-lactamases were determined by genotypic methods, including WGS. The OXA-10 variants were cloned in PAO1 to assess their impact on resistance. Models for the OXA-10 derivatives were constructed to evaluate the structural impact of the amino acid changes. Results The same XDR ST253 P. aeruginosa clone was detected in all four cases evaluated. All initial isolates showed OprD deficiency, produced an OXA-10 enzyme and were susceptible to ceftazidime, ceftolozane/tazobactam, ceftazidime/avibactam and colistin. During treatment, the isolates developed resistance to all cephalosporins. Comparative genomic analysis revealed that the evolved resistant isolates had acquired mutations in the OXA-10 enzyme: OXA-14 (Gly157Asp), OXA-794 (Trp154Cys), OXA-795 (ΔPhe153-Trp154) and OXA-824 (Asn143Lys). PAO1 transformants producing the evolved OXA-10 derivatives showed enhanced ceftolozane/tazobactam and ceftazidime/avibactam resistance but decreased meropenem MICs in a PAO1 background. Imipenem/relebactam retained activity against all strains. Homology models revealed important changes in regions adjacent to the active site of the OXA-10 enzyme. The blaOXA-10 gene was plasmid borne and acquired due to transposition of Tn6746 in the pHUPM plasmid scaffold. Conclusions Modification of OXA-10 is a mechanism involved in the in vivo acquisition of resistance to cephalosporin/β-lactamase inhibitor combinations in P. aeruginosa.

scholarly journals Phenotypic Characterization of Two Ancylostoma caninum Isolates with Different Susceptibilities to the Anthelmintic Pyrantel

2008 ◽  
Vol 52 (11) ◽  
pp. 3980-3986 ◽  
Author(s):  
Steven R. Kopp ◽  
Glen T. Coleman ◽  
James S. McCarthy ◽  
Andrew C. Kotze
Keyword(s):  
Nicotinic Acetylcholine Receptors ◽  
Acetylcholine Receptors ◽  
Resistance Mechanism ◽  
Fold Increase ◽  
Phenotypic Characterization ◽  
Gastrointestinal Helminths ◽  
Ancylostoma Caninum ◽  
High Level ◽  
Level Resistance

ABSTRACT The anthelmintic pyrantel plays an important role in the control of gastrointestinal helminths of humans and domestic animals. Despite the demonstration of pyrantel resistance in several helminth species over the last 20 years, the resistance mechanism remains unclear. It has been hypothesized that resistance may arise as a consequence of changes to the relative proportions of subpopulations of nicotinic acetylcholine receptors (nAchRs). To test this hypothesis, we examined the responses of two isolates of the canine hookworm Ancylostoma caninum with low-level resistance (isolate NT) and high-level resistance (isolate PR) to pyrantel to nicotinic agonist drugs reported to be selective for three nAchR subtypes. We used larval motility and conformation assays and force transduction experiments with adult worms. Pyrantel and levamisole were less potent against larvae of isolate PR than larvae of isolate NT (up to an 18-fold increase in the 50% inhibitory concentration); on the other hand, bephenium was more potent against larvae of isolate PR than larvae of isolate NT (twofold) and nicotine had the same potency against larvae of both isolates. In adults, pyrantel, levamisole, and nicotine were less potent against isolate PR than isolate NT (two- to threefold), but the potency of bephenium against the two isolates was equivalent. Our data indicate a complex pattern of nAchRs in this species and suggest that the two isolates differ in their relative sensitivities to agonists targeting different nAchRs.

scholarly journals Phenotypic characterization of R-factor tetracycline resistance determinants

1974 ◽  
Vol 24 (3) ◽  
pp. 333-343 ◽  
Author(s):  
T. J. Foster ◽  
Áine Walsh
Keyword(s):  
Tetracycline Resistance ◽  
Phenotypic Characterization ◽  
Resistance Determinants ◽  
R Factor ◽  
Moderate Resistance ◽  
High Level ◽  
R Factors ◽  
Phenotypic Groups ◽  
Level Resistance

SUMMARYThe tetracycline-resistance determinants of R-factors from different compatibility groups have been tested inEscherichia coliK12 and phenotypically classified into two major classes. Class I determinants confer high-level resistance to tetracycline (> 100 μg/ml) and moderate resistance to minocycline (5–25 μg/ml) while those of Class II gave moderate resistance to tetracycline (50–70 μg/ml) and low resistance to minocycline. Each class was subdivided because of variation in resistance profiles and in the abilities of tetracycline and minocycline to induce increased resistance. Strains carrying two compatible TetrR-factors of the same or different phenotypic groups did not show increased tetracycline resistance.

Comparative genomic analysis of a mammalian β-defensin gene cluster

2007 ◽  
Vol 30 (3) ◽  
pp. 213-222 ◽  
Author(s):  
Yashwanth Radhakrishnan ◽  
Mario A. Fares ◽  
Frank S. French ◽  
Susan H. Hall
Keyword(s):  
Positive Selection ◽  
Gene Cluster ◽  
Genomic Analysis ◽  
Urogenital Tract ◽  
Comparative Genomic ◽  
Evolutionary Analysis ◽  
Defensin Gene ◽  
Duplication Events ◽  
Molecular Evolutionary Analysis

Comparative genomic analyses have yielded valuable insights into conserved and divergent aspects of gene function, regulation, and evolution. Herein, we describe the characterization of a mouse β-defensin gene cluster locus on chromosome 2F6. In addition, we present the evolutionary analysis of this cluster and its human, rhesus, and rat orthologs. Expression analysis in mouse revealed the occurrence of defensin cluster transcripts in multiple tissues, with the highest abundance in the urogenital tract. Molecular evolutionary analysis suggests that this cluster originated by a series of duplication events, and by positive selection occurring even after the rodent-primate split. In addition, the constraints analysis showed higher positive selection in rodents than in primates, especially distal to the six-cysteine array. Positive selection in the evolution of these defensins may relate not only to the evolving enhancement of ancestral host defense but also to functional innovations in reproduction. The multiplicity of defensins and their preferential overexpression in the urogenital tract indicate that defensins function in the protection and maintenance of fertility.

scholarly journals Isolation, phenotypic characterization and comparative genomic analysis of 2019SD1, a polyvalent enterobacteria phage

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Prince Kumar ◽  
Mukesh K. Meghvansi ◽  
D. V. Kamboj
Keyword(s):  
Sequence Data ◽  
Burst Size ◽  
Genomic Analysis ◽  
Dna Helicase ◽  
Shigella Dysenteriae ◽  
Whole Genome Sequence ◽  
Phenotypic Characterization ◽  
Comparative Genomic ◽  
Tail Fiber ◽  
Parsimony Method

AbstractShigella has the remarkable capability to acquire antibiotic resistance rapidly thereby posing a significant public health challenge for the effective treatment of dysentery (Shigellosis). The phage therapy has been proven as an effective alternative strategy for controlling Shigella infections. In this study, we illustrate the isolation and detailed characterization of a polyvalent phage 2019SD1, which demonstrates lytic activity against Shigella dysenteriae, Escherichia coli, Vibrio cholerae, Enterococcus saccharolyticus and Enterococcus faecium. The newly isolated phage 2019SD1 shows adsorption time < 6 min, a latent period of 20 min and burst size of 151 PFU per bacterial cell. 2019SD1 exhibits considerable stability in a wide pH range and survives an hour at 50 °C. Under transmission electron microscope, 2019SD1 shows an icosahedral capsid (60 nm dia) and a 140 nm long tail. Further, detailed bioinformatic analyses of whole genome sequence data obtained through Oxford Nanopore platform revealed that 2019SD1 belongs to genus Hanrivervirus of subfamily Tempevirinae under the family Drexlerviridae. The concatenated protein phylogeny of 2019SD1 with the members of Drexlerviridae taking four genes (DNA Primase, ATP Dependent DNA Helicase, Large Terminase Protein, and Portal Protein) using the maximum parsimony method also suggested that 2019SD1 formed a distinct clade with the closest match of the taxa belonging to the genus Hanrivervirus. The genome analysis data indicate the occurrence of putative tail fiber proteins and DNA methylation mechanism. In addition, 2019SD1 has a well-established anti-host defence system as suggested through identification of putative anti-CRISPR and anti-restriction endonuclease systems thereby also indicating its biocontrol potential.

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