scholarly journals Metronidazole Resistance in Prevotella spp. and Description of a New nim Gene in Prevotella baroniae

2009 ◽  
Vol 54 (1) ◽  
pp. 60-64 ◽  
Author(s):  
C. Alauzet ◽  
F. Mory ◽  
C. Teyssier ◽  
H. Hallage ◽  
J. P. Carlier ◽  
...  
Keyword(s):  
Sequence Analysis ◽  
Prolonged Exposure ◽  
Tertiary Care ◽  
Single Copy ◽  
Clinical Isolates ◽  
Teaching Hospitals ◽  
Rrna Gene ◽  
Prolonged Incubation ◽  
Sequence Elements ◽  
High Level

ABSTRACT Nonduplicate clinical isolates of Prevotella spp. recovered from patients hospitalized between 2003 and 2006 in two French tertiary-care teaching hospitals were investigated for their susceptibility to metronidazole and the presence of nim genes. Of the 188 strains tested, 3 isolates displayed reduced susceptibility to metronidazole after 48 h of incubation, while 27 additional isolates exhibited heterogeneous resistance after prolonged incubation; all 30 of the isolates were nim negative. Among the remaining 158 isolates, 7 nim-positive isolates were detected. All of these strains were identified as Prevotella baroniae by 16S rRNA gene sequence analysis and contained a new nim gene, named nimI, as determined by DNA sequence analysis. Chromosomal localization of this single-copy gene was demonstrated in all clinical isolates as well as in type strain P. baroniae DSM 16972 by using Southern hybridization. No known associated insertion sequence elements were detected upstream of the nimI gene in any of the nim-positive strains by PCR mapping. After prolonged exposure to metronidazole, stable resistant subpopulations could be selected in nimI-positive Prevotella isolates (n = 6) as well as in nim-negative Prevotella isolates (n = 6), irrespective of their initial susceptibility to this antibiotic. This study is the first description of a new nitroimidazole resistance gene in P. baroniae which seems to be silent and which might be intrinsic in this species. Moreover, our findings highlight the fact that high-level resistance to metronidazole may be easily induced in both nim-positive and nim-negative Prevotella sp. strains.

scholarly journals Tetrahymena thermophila mutants defective in the developmentally programmed maturation and maintenance of the rDNA minichromosome.

Genetics ◽  
1994 ◽  
Vol 137 (2) ◽  
pp. 455-466 ◽  
Author(s):  
G M Kapler ◽  
E Orias ◽  
E H Blackburn
Keyword(s):  
De Novo ◽  
Tetrahymena Thermophila ◽  
Single Copy ◽  
Rrna Gene ◽  
Cis Acting ◽  
New Class ◽  
Controlled Processing ◽  
Sequence Elements ◽  
High Level ◽  
Processing Steps

Abstract The abundant rDNA minichromosome of Tetrahymena thermophila is generated by a series of developmentally controlled processing steps, termed rDNA maturation, during the formation of the new macronucleus in conjugating cells. rDNA maturation involves excision of a region encoding the single copy rRNA gene (rDNA) from its germline location, rearrangement of the rDNA into a palindromic minichromosome, de novo telomere addition, and amplification to approximately 10(4) copies. The rDNA is maintained at this high level in vegetatively growing cells. Using a previously developed genetic scheme for studying rDNA maturation and maintenance, we report the isolation of a new class of mutants defective for rDNA maturation. Several new rDNA maintenance mutants were also obtained. The maturation mutant, rmm10, is severely defective for the production of both monomeric and palindromic rDNA in the developing macronucleus. The mm10 mutation is recessive-lethal and cis-acting. None of the previously identified DNA sequence elements that control rDNA maturation or maintenance is mutated in rmm10. Therefore, additional cis-acting sequence elements must be required for rDNA maturation. Based on our current understanding of rDNA maturation processes, we suggest that the rmm10 mutation affects rDNA excision rather than subsequent rDNA amplification/replication.

scholarly journals Association between 16S rRNA gene mutations and susceptibility to amikacin in Mycobacterium avium Complex and Mycobacterium abscessus clinical isolates

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Su-Young Kim ◽  
Dae Hun Kim ◽  
Seong Mi Moon ◽  
Ju Yeun Song ◽  
Hee Jae Huh ◽  
...  
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Mycobacterium Avium ◽  
Inhibitory Concentration ◽  
Gene Mutations ◽  
Mycobacterium Abscessus ◽  
Clinical Isolates ◽  
Rrna Gene ◽  
High Level ◽  
Culture Conversion

AbstractWe evaluated the association between 16S rRNA gene (rrs) mutations and susceptibility in clinical isolates of amikacin-resistant nontuberculous mycobacteria (NTM) in NTM-pulmonary disease (PD) patients. Susceptibility was retested for 134 amikacin-resistant isolates (minimum inhibitory concentration [MIC] ≥ 64 µg/ml) from 86 patients. Amikacin resistance was reconfirmed in 102 NTM isolates from 62 patients with either Mycobacterium avium complex-PD (MAC-PD) (n = 54) or M. abscessus-PD (n = 8). MICs and rrs mutations were evaluated for 318 single colonies from these isolates. For the 54 MAC-PD patients, rrs mutations were present in 34 isolates (63%), comprising all 31 isolates with amikacin MICs ≥ 128 µg/ml, but only three of 23 isolates with an MIC = 64 µg/ml. For the eight M. abscessus-PD patients, all amikacin-resistant (MIC ≥ 64 µg/ml) isolates had rrs mutations. In amikacin-resistant isolates, the A1408G mutation (n = 29) was most common. Two novel mutations, C1496T and T1498A, were also identified. The culture conversion rate did not differ by amikacin MIC. Overall, all high-level and 13% (3/23) of low-level amikacin-resistant MAC isolates had rrs mutations whereas mutations were present in all amikacin-resistant M. abscessus isolates. These findings are valuable for managing MAC- and M. abscessus-PD and suggest the importance of phenotypic and genotypic susceptibility testing.

scholarly journals Diversity and Effectivity of Indigenous Mesorhizobium Strains for Chickpea (Cicer arietinum L.) in Myanmar

Agronomy ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 287 ◽  
Author(s):  
Khin Myat Soe ◽  
Aung Zaw Htwe ◽  
Kyi Moe ◽  
Abiko Tomomi ◽  
Takeo Yamakawa
Keyword(s):  
Sequence Analysis ◽  
Cicer Arietinum ◽  
Acetylene Reduction ◽  
Dry Weight ◽  
Acetylene Reduction Activity ◽  
Rrna Gene ◽  
Cicer Arietinum L ◽  
Reduction Activity ◽  
Legume Production ◽  
High Level

Chickpea (Cicer arietinum L.) is one of the world’s main leguminous crops that provide chief source of food for humans. In the present study, we characterized thirty isolates of indigenous chickpea rhizobia from Myanmar based on the sequence analysis of the bacterial 16S rRNA gene. The sequence analysis confirmed that all isolates were categorized and identified as the genus Mesorhizobium and they were conspecific with M. plurifarium, M. muliense, M. tianshanense, and M. sp. This is the first report describing M. muliense, M. tianshanense, and M. plurifurium from different geographical distribution of indigenous mesorhizobia of chickpea in Myanmar. In order to substitute the use of chemical fertilizers in legume production, there is a need for the production of Biofertilizers with rhizobial inoculants. The effectiveness of Myanmar Mesorhizobim strains isolated from soil samples of major chickpea growing areas of Myanmar for plant growth and nitrogen fixation were studied in pot experiments. The nodule dry weight and acetylene reduction activity of the plant inoculated with Mesorhizobium tianshanense SalCP19 was significantly higher than the other tested isolates in Yezin-4 chickpea variety. But, Mesorhizobium sp. SalCP17 was showed high level of acetylene reduction activity per plant in Yezin-6 chickpea variety.

scholarly journals Molecular Epidemiology of Clinical Isolates of Carbapenem-Resistant Acinetobacter spp. from Chinese Hospitals

2007 ◽  
Vol 51 (11) ◽  
pp. 4022-4028 ◽  
Author(s):  
Hui Wang ◽  
Ping Guo ◽  
Hongli Sun ◽  
He Wang ◽  
Qiwen Yang ◽  
...  
Keyword(s):  
Molecular Epidemiology ◽  
Restriction Analysis ◽  
Carbapenem Resistance ◽  
Clinical Isolates ◽  
Teaching Hospitals ◽  
Class 1 Integron ◽  
Carbapenemase Gene ◽  
Class 1 ◽  
Clonal Spread ◽  
High Level

ABSTRACT Carbapenem resistance in Acinetobacter spp. is an emerging problem in China. We investigated the molecular epidemiology and carbapenemase genes of 221 nonrepetitive imipenem-resistant clinical isolates of Acinetobacter spp. collected from 1999 to 2005 at 11 teaching hospitals in China. Genotyping by pulsed-field gel electrophoresis (PFGE) found 15 PFGE patterns. Of these, one (clone P) was identified at four hospitals in Beijing and another (clone A) at four geographically disparate cities. Most imipenem-resistant isolates exhibited high-level resistance to all β-lactams and were only susceptible to colistin. bla OXA-23-like genes were found in 97.7% of isolates. Sequencing performed on 60 representative isolates confirmed the presence of the bla OXA-23 carbapenemase gene. Analysis of the genetic context of bla OXA-23 showed the presence of ISAba1 upstream of bla OXA-23. All of the 187 A. baumannii isolates identified by amplified RNA gene restriction analysis carried a bla OXA-51-like oxacillinase gene, while this gene was absent from isolates of other species. Sequencing indicated the presence of bla OXA-66 for 18 representative isolates. Seven isolates of one clone (clone T) carried the plasmid-mediated bla OXA-58 carbapenemase gene, while one isolate of another clone (clone L) carried the bla OXA-72 carbapenemase gene. Only 1 isolate of clone Q carried the bla IMP-8 metallo-β-lactamase gene, located in a class 1 integron. Of 221 isolates, 77.8% carried bla PER-1-like genes. Eleven different structures of class 1 integrons were detected, and most integrons carried genes mediating resistance to aminoglycosides, rifampin, and chloramphenicol. These findings indicated clonal spread of imipenem-resistant Acinetobacter spp. and wide dissemination of the OXA-23 carbapenemase in China.

Intra-chromosomal heterogeneity between the four 16S rRNA gene copies in the genus Veillonella: implications for phylogeny and taxonomy

Microbiology ◽  
2003 ◽  
Vol 149 (6) ◽  
pp. 1493-1501 ◽  
Author(s):  
Hélène Marchandin ◽  
Corinne Teyssier ◽  
Michèle Siméon de Buochberg ◽  
Hélène Jean-Pierre ◽  
Christian Carriere ◽  
...  
Keyword(s):  
16S Rrna ◽  
16S Rdna ◽  
Clinical Isolates ◽  
Clinical Strain ◽  
Species Differentiation ◽  
Rrna Gene ◽  
Rdna Sequences ◽  
Gene Copies ◽  
High Level ◽  
Human Flora

Among the seven species characterized within the genus Veillonella, three (Veillonella dispar, Veillonella parvula and Veillonella atypica) have so far been isolated from human flora and during infectious processes. Sequencing and analysis of 16S rDNA (rrs) has been described as the best method for identification of Veillonella strains at the species level since phenotypic characteristics are unable to differentiate between species. rrs sequencing for the three species isolated from humans showed more than 98 % identity between them. Four rrs copies were found in the reference strains and in all the clinical isolates studied. The sequences of each rrs were determined for the clinical strain ADV 360.1, and they showed a relatively high level of heterogeneity (1·43 %). In the majority of cases, polymorphic positions corresponded to nucleotides allowing differentiation between the three species isolated from humans. Moreover, variability observed between rrs copies was higher than that between 16S rDNA sequences of V. parvula and V. dispar. Phylogenetic analysis showed that polymorphism between rrs copies affected the position of strain ADV 360.1 in the tree. Variable positions occurred in stems and loops belonging to variable and hypervariable regions of the 16S rRNA secondary structure but did not change the overall structure of the 16S rRNA. PCR-RFLP experiments performed on 27 clinical isolates of Veillonella sp. suggested that inter-rrs heterogeneity occurs widely among the members of the genus Veillonella. These results, together with the lack of phenotypic criteria for species differentiation, give preliminary arguments for unification of V. dispar and V. parvula.

Antimicrobial susceptibility and mechanisms of high-level macrolide resistance in clinical isolates of Moraxella nonliquefaciens

2014 ◽  
Vol 63 (2) ◽  
pp. 242-247 ◽  
Author(s):  
Shotaro Nonaka ◽  
Kosuke Matsuzaki ◽  
Tomoya Kazama ◽  
Hiroyuki Nishiyama ◽  
Yoko Ida ◽  
...  
Keyword(s):  
Antimicrobial Susceptibility ◽  
Ribosomal Proteins ◽  
Macrolide Resistance ◽  
Clinical Isolates ◽  
23S Rrna ◽  
Rrna Gene ◽  
Efflux System ◽  
Strong Activity ◽  
23S Rrna Gene ◽  
High Level

We investigated antimicrobial susceptibility and the molecular mechanism involved in conferring high-level macrolide resistance in 47 clinical isolates of Moraxella nonliquefaciens from Japan. Antimicrobial susceptibility was determined using Etest and agar dilution methods. Thirty-two erythromycin-non-susceptible strains were evaluated for the possibility of clonal spreading, using PFGE. To analyse the mechanism related to macrolide resistance, mutations in the 23S rRNA gene and the ribosomal proteins, and the presence of methylase genes were investigated by PCR and sequencing. The efflux system was examined using appropriate inhibitors. Penicillin, ampicillin, amoxicillin, cefixime, levofloxacin and antimicrobials containing β-lactamase inhibitors showed strong activity against 47 M. nonliquefaciens isolates. Thirty-two (68.1 %) of the 47 isolates showed high-level MICs to macrolides (MIC ≥128 mg l−1) and shared the A2058T mutation in the 23S rRNA gene. The geometric mean MIC to macrolides of A2058T-mutated strains was significantly higher than that of WT strains (P<0.0001). Thirty-two isolates with high-level macrolide MICs clustered into 30 patterns on the basis of the PFGE dendrogram, indicating that the macrolide-resistant strains were not clonal. In contrast, no common mutations of the ribosomal proteins or methylase genes, or overproduction of the efflux system were observed in A2058T-mutated strains. Moreover, of the 47 M. nonliquefaciens strains, 43 (91.5 %) were bro-1 and 4 (8.5 %) were bro-2 positive. Our results suggest that most M. nonliquefaciens clinical isolates show high-level macrolide resistance conferred by the A2058T mutation in the 23S rRNA gene. This study represents the first characterization of M. nonliquefaciens.

scholarly journals Comparison of Tn1546-Like Elements in Vancomycin-Resistant Staphylococcus aureus Isolates from Michigan and Pennsylvania

2005 ◽  
Vol 49 (1) ◽  
pp. 470-472 ◽  
Author(s):  
Nancye C. Clark ◽  
Linda M. Weigel ◽  
Jean B. Patel ◽  
Fred C. Tenover
Keyword(s):  
Staphylococcus Aureus ◽  
Sequence Analysis ◽  
Dna Sequence ◽  
Intergenic Region ◽  
Mobile Genetic Element ◽  
Clinical Isolates ◽  
Genetic Element ◽  
Vancomycin Resistant ◽  
High Level ◽  
Genetic Events

ABSTRACT In 2002, the first two clinical isolates of vancomycin-resistant Staphylococcus aureus (VRSA) containing vanA were recovered in Michigan and Pennsylvania. Tn1546, a mobile genetic element that encodes high-level vancomycin resistance in enterococci, was present in both isolates. With PCR and DNA sequence analysis, we compared the Tn1546 elements from each isolate to the prototype Tn1546 element. The Michigan VRSA element was identical to the prototype Tn1546 element. The Pennsylvania VRSA element showed three distinct modifications: a deletion of nucleotides 1 to 3098 at the 5′ end, which eliminated the orf1 region; an 809-bp IS1216V-like element inserted before nucleotide 3099 of Tn1546; and an inverted 1,499-bp IS1251-like element inserted into the vanSH intergenic region. These differences in the Tn1546-like elements indicate that the first two VRSA isolates were the result of independent genetic events.

scholarly journals High Level Plasmid-Mediated Quinolone Resistance in Clinical Infections at a Tertiary Healthcare Institution in South-West Nigeria

2021 ◽  
Author(s):  
Abiodun Ronke Ojewuyi ◽  
Babatunde Odetoyin ◽  
Aaron Oladipo Aboderin
Keyword(s):  
Tertiary Care ◽  
Wide Distribution ◽  
Quinolone Resistance ◽  
Clinical Isolates ◽  
Care Hospital ◽  
Cross Sectional ◽  
Diffusion Technique ◽  
High Prevalence ◽  
Tertiary Healthcare ◽  
High Level

Abstract Background Plasmid-mediated quinolone resistance (PMQR) has become a growing clinical concern worldwide. Recent reports from Nigeria revealed that qunolone resistant clinical isolates have become commomplace. However, few reports regarding the prevalence of PMQR are available. Hence, this study aimed to determine the prevalence of PMQR genes in qunolone resistant clinical isolates from a tertiary care hospital in Nigeria. Methods This was a cross-sectional hospital based study involving 390 non-repetitive Gram negative bacilli from diverse clinical infections. The isolates were characterized by the MicrobactTM identification kit and their susceptibility patterns determined by the Kirby-Bauer disc diffusion technique. All quinolone resistant isolates were investigated for the carriage of PMQR genes by multiplex polymerase chain reaction (PCR). Data analysis was with appropriate descriptive and inferential statistics.Results The isolates were distributed as Escherichia coli (n=121; 31.0%), Klebsiella species (n= 112;28.7%), Pseudomonas aeruginosa (n=59;15.1%), Proteus species (n=43;11.0%), Salmonella species (n=6;1.3%) and others. They were commonly resistant to nalidixic (62.6%), co-amoxiclav (57.7%); norfloxacin (52.3%), ofloxacin(52.1%) and ciprofloxacin(51.0%), but were least resistant to imipenem; (n=36; 9.2%). Out of 244 isolates that were resistant to at least one quinolone, 180 (73.8%) harboured one or more PMQR gene with a high prevalence of efflux-mediating determinants (qepA, 22.5%; oqxAB, 21.1%), and the aminoglycoside acetyltransferase (aac(6’)-Ib-cr, 19.7%). Proportionately low level of target-protecting determinants; qnrB, 13.2%; qnrS, 8.7%; qnrA, 5.9%; qnrD, 4.5% and qnrC, 4.2% were found in these isolates.Conclusion There is high level quinolone resistance and wide distribution of PMQR genes in clinical isolates in Nigeria with a preponderance of Efflux-mediating determinants and the aminoglycoside acetyltransferase. This emphasizes the need for regular resistance surveillance and antimicrobial stewardship to guide the appropriate and judicious use of antibiotics.

scholarly journals PROFILE OF STAPHYLOCOCCUS AUREUS ISOLATED FROM PATIENTS ADMITTED IN A TERTIARY CARE HOSPITAL WITH ESPECIAL REFERENCE TO METHICILLIN RESISTANCE

2020 ◽  
pp. 1-2
Author(s):  
Asmita Singh ◽  
Anita Pandey ◽  
Amit Singh ◽  
Priyanka Chaturvedi
Keyword(s):  
Staphylococcus Aureus ◽  
Antimicrobial Agents ◽  
Tertiary Care Hospital ◽  
Methicillin Resistance ◽  
Tertiary Care ◽  
Hospital Setting ◽  
Clinical Isolates ◽  
Care Hospital ◽  
Wide Range ◽  
High Level

BACKGROUND: Staphylococcus aureus is a major human pathogen that causes wide range of clinical infections. Methicillin-resistant Staphylococcus aureus(MRSA) is endemic in India and is a dangerous pathogen causing hospital acquired infection leadings to signicant morbidity and mortality. OBJECTIVE:To study the prole of Staphylococcus aureusisolated from patients admitted in a tertiary care hospital. RESULT: Majority of clinical isolates of S.aurueswas obtained from patients of skin and soft tissue infection(54.66%) followed by those suffering from respiratory infection (13.33%), blood stream infection (13.33%) and UTI(8%). S.aureus was predominantly isolated from IPD samples, maximum cases were in the age group of 31-40 years and males outnumbered females. There was predominance of MRSA 112 (74.66%)which showed high level of resistance to penicillin (100%), ciprooxacin (82.14 %), co-trimoxazole (79.46%) and moxioxacin(85.71%). All the clinical isolates of S.aureuswere sensitive to linezolid andvancomycin (MIC <1ugm/ml). CONCLUSIONS: The clinical isolates of S.aureusshowed high level of resistance to various antimicrobial agents which is a signicant nosocomial threat. Surveillance and infection control practices should be carried out to prevent cross transmission of such resistant pathogen within the hospital setting

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