Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 59
Filtrar
Mais filtros

Base de dados
Tipo de documento
Intervalo de ano de publicação
1.
Artigo em Inglês | MEDLINE | ID: mdl-38180015

RESUMO

The naming of prokaryotes is governed by the International Code of Nomenclature of Prokaryotes (ICNP) and partially by the International Code of Nomenclature for Algae, Fungi and Plants (ICN). Such codes must be able to determine names of taxa in a universal and unambiguous manner, thus serving as a common language across different fields and activities. This unity is undermined when a new code of nomenclature emerges that overlaps in scope with an established, time-tested code and uses the same format of names but assigns different nomenclatural status values to the names. The resulting nomenclatural confusion is not beneficial to the wider scientific community. Such ambiguity is expected to result from the establishment of the 'Code of Nomenclature of Prokaryotes Described from DNA Sequence Data' ('SeqCode'), which is in general and specific conflict with the ICNP and the ICN. Shortcomings in the interpretation of the ICNP may have exacerbated the incompatibility between the codes. It is reiterated as to why proposals to accept sequences as nomenclatural types of species and subspecies with validly published names, now implemented in the SeqCode, have not been implemented by the International Committee on Systematics of Prokaryotes (ICSP), which oversees the ICNP. The absence of certain regulations from the ICNP for the naming of as yet uncultivated prokaryotes is an acceptable scientific argument, although it does not justify the establishment of a separate code. Moreover, the proposals rejected by the ICSP are unnecessary to adequately regulate the naming of uncultivated prokaryotes. To provide a better service to the wider scientific community, an alternative proposal to emend the ICNP is presented, which would result in Candidatus names being regulated analogously to validly published names. This proposal is fully consistent with previous ICSP decisions, preserves the essential unity of nomenclature and avoids the expected nomenclatural confusion.


Assuntos
Ácidos Graxos , Filogenia , Análise de Sequência de DNA , RNA Ribossômico 16S/genética , DNA Bacteriano/genética , Técnicas de Tipagem Bacteriana , Composição de Bases , Ácidos Graxos/química
2.
J Clin Microbiol ; 59(4)2021 03 19.
Artigo em Inglês | MEDLINE | ID: mdl-33472899

RESUMO

Achromobacter species are increasingly being detected in patients with cystic fibrosis (CF), and this emerging pathogen is associated with antibiotic resistance and more-severe disease outcomes. Nonetheless, little is known about the extent of transmission and antibiotic resistance development in Achromobacter infections. We sequenced the genomes of 101 Achromobacter clinical isolates (identified as Achromobacter xylosoxidans based on matrix-assister laser desorption ionization-time of flight [MALDI-TOF] or API N20 typing) collected from 51 patients with CF-the largest longitudinal data set to date. We performed phylogenetic analysis on the genomes and combined this with epidemiological and antibiotic resistance data to identify patient-to-patient transmission and the development of antibiotic resistance. We confirmed that the MALDI-TOF or API N20 method was not sufficient for Achromobacter species-level typing and that the population of Achromobacter isolates was composed of five different species, among which A. xylosoxidans accounted for 52% of infections. Most patients were infected by unique Achromobacter clone types; nonetheless, suspected patient-to-patient transmission cases identified by shared clone types were observed in 35% (n = 18) of patients. In 15 of 16 cases, the suspected transmissions were further supported by genome- or clinic visit-based epidemiological analysis. Finally, we found that resistance developed over time. We show that whole-genome sequencing (WGS) is essential for Achromobacter species typing and identification of patient-to-patient transmission, which was revealed for Achromobacter ruhlandii, A. xylosoxidans, and, for the first time, Achromobacter insuavis Furthermore, we show that the development of antibiotic resistance is associated with chronic Achromobacter infections. Our findings emphasize that transmission and antibiotic resistance should be considered in future treatment strategies.


Assuntos
Achromobacter , Fibrose Cística , Infecções por Bactérias Gram-Negativas , Achromobacter/genética , Fibrose Cística/complicações , Resistência Microbiana a Medicamentos , Infecções por Bactérias Gram-Negativas/epidemiologia , Humanos , Filogenia
3.
Eur J Clin Microbiol Infect Dis ; 40(10): 2077-2085, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33891188

RESUMO

Haemophilus influenzae is a common cause of mucosal infections that warrants accurate surveillance. We aimed to assess the prevalence of the species in clinical specimens, and characterise population structure and resistance to aminopenicillins by whole genome sequencing.We assessed the point prevalence by entering the database records of 1 day in Denmark and examined the genome sequences of nationwide, collected isolates from the same day. The prevalence of H. influenzae in clinical samples on the 10th of January 2018 was 1.78 per 100,000 person-days (all samples), and 2.47 per 1000 hospital bed-days (hospital samples). Of 2009 bacteria deemed clinically relevant and collected in a concerted action by the Danish departments of clinical microbiology, 62 (3.1%) were H. influenzae. All 62 isolates belonged to phylogenetic group I and were unencapsulated. Three strains from separate Danish regions had identical core genome sequences, but a small number of intergenic mutations testified to circulating clones, rather than individual cases of patient-to-patient transmission. The TEM-1 ß-lactamase gene was present in 24 strains, while 13 strains were genetically categorised as ampicillin-resistant due to substitutions in penicillin-binding protein 3; shared patterns of amino acid substitutions in unrelated strains indicated putative lateral transfer of chromosomal resistance. Circulating clones of H. influenzae are frequent, and host factors, rather than direct transmission of epidemic strains, may be the primary cause of infection. The bleak presence of ampicillin resistance revealed by sequencing of point prevalence strains underscores the necessity for close examination of testing methods.


Assuntos
Resistência a Ampicilina , Antibacterianos/farmacologia , Infecções por Haemophilus/microbiologia , Haemophilus influenzae/efeitos dos fármacos , Haemophilus influenzae/isolamento & purificação , Ampicilina/farmacologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Dinamarca/epidemiologia , Infecções por Haemophilus/epidemiologia , Haemophilus influenzae/classificação , Haemophilus influenzae/genética , Humanos , Filogenia , beta-Lactamases/genética , beta-Lactamases/metabolismo
4.
Int J Med Microbiol ; 310(2): 151393, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31969255

RESUMO

Bacteria colonising the lungs of cystic fibrosis (CF) patients encounter high selective pressures. Hypermutation facilitates adaptation to fluctuating environments, and hypermutator strains are frequently isolated from CF patients. We investigated the prevalence of hypermutator isolates of Achromobacter spp. among patients affiliated with the CF Centre in Aarhus, Denmark. By exposure to rifampicin, the mutation frequency was determined for 90 isolates of Achromobacter spp. cultured from 42 CF patients; 20 infections were categorised as chronic, 22 as intermittent. The genetic mechanisms of hypermutation were examined by comparing DNA repair gene sequences from hypermutator and normomutator isolates. Achromobacter spp. cultured from 11 patients were categorised as hypermutators, and this phenotype was exclusively associated with chronic infections. Isolates of the Danish epidemic strain (DES) of Achromobacter ruhlandii cultured from patients from both Danish CF centres showed elevated mutation frequencies. The hypermutator state of Achromobacter spp. was most commonly associated with nonsynonymous mutations in the DNA mismatch repair gene mutS; a single clone had developed a substitution in the S-adenosyl-L-methionine-dependent methyltransferase putatively involved in DNA repair mechanisms, but not previously linked to the hypermutator phenotype. Hypermutation is prevalent among clinical isolates of Achromobacter spp. and could be a key determinant for the extraordinary adaptation and persistence of DES.


Assuntos
Achromobacter/genética , Fibrose Cística/microbiologia , Taxa de Mutação , Mutação , Achromobacter/efeitos dos fármacos , Antibacterianos/farmacologia , Doença Crônica , Reparo de Erro de Pareamento de DNA , Dinamarca , Humanos , Proteína MutS de Ligação de DNA com Erro de Pareamento/genética , Fenótipo , Prevalência , Rifampina/farmacologia
5.
J Clin Periodontol ; 46(8): 846-854, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31124155

RESUMO

AIM: The present study aims to determine the susceptibility of Aggregatibacter actinomycetemcomitans to amoxicillin by investigating a large collection of oral strains of diverse geographical origin. METHODS: Two hundred and fifty-seven A. actinomycetemcomitans strains were serotyped using a multiplex polymerase chain reaction, and minimal inhibitory concentration (MIC) values of amoxicillin were determined using the agar dilution method (range 0.25-8.0 mg/L). The plates were spot-wise inoculated with approximately 104 colony-forming units, incubated in 5% CO2 at 37 C°, and visually inspected after 24 and 48 hr. A MIC ≤ 2.00 mg/L was categorised as susceptible using EUCAST interpretative criteria for Haemophilus species. RESULTS: Amoxicillin MIC values varied from 0.25 mg/L to 2.00 mg/L, and all tested strains, including strains previously reported as resistant, were susceptible to amoxicillin. The MIC50 was 1.00 mg/L and the MIC90 was 2.00 mg/L. CONCLUSION: Meticulous investigation of strains including isolates previously reported as resistant could not confirm the emergence of resistance to ß-lactams in A. actinomycetemcomitans. Based on the present in vitro results, amoxicillin can be considered a key oral antimicrobial agent for treatment of A. actinomycetemcomitans.


Assuntos
Amoxicilina , Anti-Infecciosos , Aggregatibacter actinomycetemcomitans , Antibacterianos , Testes de Sensibilidade Microbiana
6.
J Clin Microbiol ; 56(7)2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29695522

RESUMO

Aggregatibacter species are commensal bacteria of human mucosal surfaces that are sometimes involved in serious invasive infections. During the investigation of strains cultured from various clinical specimens, we encountered a coherent group of 10 isolates that could not be allocated to any validly named species by phenotype, mass spectrometry, or partial 16S rRNA gene sequencing. Whole-genome sequencing revealed a phylogenetic cluster related to but separate from Aggregatibacter aphrophilus The mean in silico DNA hybridization value for strains of the new cluster versus A. aphrophilus was 56% (range, 53.7 to 58.0%), whereas the average nucleotide identity was 94.4% (range, 93.9 to 94.8%). The new cluster exhibited aggregative properties typical of the genus Aggregatibacter Key phenotypic tests for discrimination of the new cluster from validly named Aggregatibacter species are alanine-phenylalanine-proline arylamidase, N-acetylglucosamine, and ß-galactosidase. The name Aggregatibacter kilianii is proposed, with PN_528 (CCUG 70536T or DSM 105094T) as the type strain.


Assuntos
Aggregatibacter/classificação , Aggregatibacter/genética , Genoma Bacteriano/genética , Infecções por Pasteurellaceae/microbiologia , Filogenia , Aggregatibacter/fisiologia , Hibridização Genômica Comparativa , DNA Bacteriano/genética , Humanos , Fenótipo , Análise de Sequência de DNA , Homologia de Sequência do Ácido Nucleico , Especificidade da Espécie
7.
J Antimicrob Chemother ; 72(9): 2544-2547, 2017 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-28582518

RESUMO

Objectives: To determine the association of amino acid substitutions in PBP3 with ß-lactam susceptibility in Haemophilus parainfluenzae. Methods: Single and multiple amino acid mutations at positions 385, 511 and 526 were introduced into PBP3 of a ß-lactam-susceptible H. parainfluenzae strain using site-directed mutagenesis. Recombinants were also generated using PCR-amplified ftsI from clinical strains encoding multiple amino acid substitutions. MICs of ampicillin, cefuroxime, cefotaxime and ceftriaxone were determined using Etest®. Results: Transformation of a susceptible strain with ftsI from clinical strains encoding four substitutions in the transpeptidase region of PBP3 conferred resistance to ampicillin, but not to cephalosporins. Introduction of ftsI from a clinical strain encoding eight substitutions conferred resistance to ampicillin, cefotaxime and ceftriaxone. MICs for recombinants were lower than those for the donor strains. Using site-directed mutagenesis, no single substitution conferred resistance to the tested ß-lactams, although V511A increased the MIC of cefuroxime to the intermediate category for intravenous administration. Recombinants encoding N526K/H/S in combination with V511A were resistant to ampicillin. Substitution S385T increased the MICs of third-generation cephalosporins if V511A was also present. Conclusions: Substitutions in PBP3 are sufficient to confer resistance to both ampicillin and third-generation cephalosporins in H. parainfluenzae. A combination of substitutions at positions Val-511 and Asn-526 confers resistance to ampicillin. Resistance to third-generation cephalosporins probably requires more than four substitutions in PBP3.


Assuntos
Substituição de Aminoácidos , Ampicilina/farmacologia , Antibacterianos/farmacologia , Cefalosporinas/farmacologia , Haemophilus parainfluenzae/efeitos dos fármacos , Haemophilus parainfluenzae/genética , Proteínas de Ligação às Penicilinas/genética , Farmacorresistência Bacteriana Múltipla/genética , Infecções por Haemophilus/microbiologia , Humanos , Testes de Sensibilidade Microbiana , Mutagênese Sítio-Dirigida , Recombinação Genética
8.
Microb Pathog ; 105: 255-259, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28254444

RESUMO

Mannitol salt agar (MSA) is often used in resources' limited laboratories for identification of S. aureus however, coagulase-negative staphylococci (CoNS) grows and ferments mannitol on MSA. 171 strains of CoNS which have been previously misidentified as S. aureus due to growth on MSA were collected from different locations in Nigeria and two methods for identification of CoNS were compared i.e. ViTEK 2 and MALDI-TOF MS with partial 16S rRNA gene sequencing as gold standard. Partial tuf gene sequencing was used for contradicting identification. All 171 strains (13 species) grew on MSA and ferments mannitol. All tested strains of S. epidermidis, S. haemolyticus, S. nepalensis, S. pasteuri, S. sciuri,, S. warneri, S. xylosus, S. capitis were correctly identified by MALDI-TOF while variable identification were observed in S. saprophyticus and S. cohnii (90%, 81%). There was low identification of S. arlettae (14%) while all strains of S. kloosii and S. gallinarum were misidentified. There is absence of S. gallinarum in the MALDI-TOF database at the period of this study. All tested strains of S. epidermidis, S. gallinarum, S. haemolyticus, S. sciuri,, S. warneri, S. xylosus and S. capitis were correctly identified by ViTEK while variable identification were observed in S. saprophyticus, S. arlettae, S. cohnii, S. kloosii, (84%, 86%, 75%, 60%) and misidentification of S. nepalensis, S. pasteuri. Partial sequencing of 16S rRNA gene was used as gold standard for most strains except S. capitis and S. xylosus where the two species were misidentified by partial sequencing of 16S rRNA contrary to MALDI-TOF and ViTEK identification. Tuf gene sequencing was used for correct identification. Characteristic growth on MSA for CoNS is also identical to S. aureus growth on the media and therefore, MSA could not differentiate between S. aureus and CoNS. The percentage accuracy of ViTEK was better than MALDI-TOF in identification of CoNS. Although partial sequencing of 16S rRNA gene was used as gold standard in this study, it could not correctly identify S. capitis and S. xylosus.


Assuntos
Proteínas de Bactérias/genética , Técnicas de Tipagem Bacteriana/métodos , RNA Ribossômico 16S/genética , Staphylococcus/crescimento & desenvolvimento , Staphylococcus/metabolismo , Ágar , Proteínas de Bactérias/metabolismo , Técnicas de Tipagem Bacteriana/instrumentação , Coagulase/genética , Coagulase/metabolismo , Meios de Cultura , Bases de Dados Factuais , Manitol , Filogenia , Reprodutibilidade dos Testes , Análise de Sequência de DNA , Cloreto de Sódio , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/instrumentação , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Staphylococcus/genética , Staphylococcus/isolamento & purificação , Staphylococcus aureus/genética , Staphylococcus aureus/crescimento & desenvolvimento , Staphylococcus aureus/isolamento & purificação , Staphylococcus aureus/metabolismo
9.
Clin Microbiol Rev ; 27(2): 214-40, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24696434

RESUMO

The aim of this review is to provide a comprehensive update on the current classification and identification of Haemophilus and Aggregatibacter species with exclusive or predominant host specificity for humans. Haemophilus influenzae and some of the other Haemophilus species are commonly encountered in the clinical microbiology laboratory and demonstrate a wide range of pathogenicity, from life-threatening invasive disease to respiratory infections to a nonpathogenic, commensal lifestyle. New species of Haemophilus have been described (Haemophilus pittmaniae and Haemophilus sputorum), and the new genus Aggregatibacter was created to accommodate some former Haemophilus and Actinobacillus species (Aggregatibacter aphrophilus, Aggregatibacter segnis, and Aggregatibacter actinomycetemcomitans). Aggregatibacter species are now a dominant etiology of infective endocarditis caused by fastidious organisms (HACEK endocarditis), and A. aphrophilus has emerged as an important cause of brain abscesses. Correct identification of Haemophilus and Aggregatibacter species based on phenotypic characterization can be challenging. It has become clear that 15 to 20% of presumptive H. influenzae isolates from the respiratory tracts of healthy individuals do not belong to this species but represent nonhemolytic variants of Haemophilus haemolyticus. Due to the limited pathogenicity of H. haemolyticus, the proportion of misidentified strains may be lower in clinical samples, but even among invasive strains, a misidentification rate of 0.5 to 2% can be found. Several methods have been investigated for differentiation of H. influenzae from its less pathogenic relatives, but a simple method for reliable discrimination is not available. With the implementation of identification by matrix-assisted laser desorption ionization-time of flight mass spectrometry, the more rarely encountered species of Haemophilus and Aggregatibacter will increasingly be identified in clinical microbiology practice. However, identification of some strains will still be problematic, necessitating DNA sequencing of multiple housekeeping gene fragments or full-length 16S rRNA genes.


Assuntos
Aggregatibacter/classificação , Aggregatibacter/fisiologia , Infecções por Haemophilus/microbiologia , Haemophilus/classificação , Haemophilus/fisiologia , Especificidade de Hospedeiro , Infecções por Pasteurellaceae/microbiologia , Aggregatibacter/isolamento & purificação , Técnicas Bacteriológicas/métodos , Haemophilus/isolamento & purificação , Infecções por Haemophilus/diagnóstico , Humanos , Técnicas de Diagnóstico Molecular , Infecções por Pasteurellaceae/diagnóstico , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos
10.
Antimicrob Agents Chemother ; 59(7): 4339-42, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25918135

RESUMO

Mutations in ftsI, encoding penicillin-binding protein 3, can cause decreased ß-lactam susceptibility in Haemophilus influenzae. Sequencing of ftsI from clinical strains has indicated interspecies recombination of ftsI between H. influenzae and Haemophilus haemolyticus. This study documented apparently unrestricted homologous recombination of ftsI between H. influenzae and H. haemolyticus in vitro. Transfer of ftsI from resistant isolates conferred similar but not identical increases in the MICs of susceptible strains of H. influenzae and H. haemolyticus.


Assuntos
Antibacterianos/farmacologia , Haemophilus influenzae/genética , Haemophilus/genética , Proteínas de Ligação às Penicilinas/genética , Resistência beta-Lactâmica/genética , beta-Lactamas/farmacologia , Ampicilina/farmacologia , Cefotaxima/farmacologia , Transferência Genética Horizontal , Recombinação Homóloga/genética , Testes de Sensibilidade Microbiana
11.
Microbiology (Reading) ; 161(12): 2310-5, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26385154

RESUMO

Only two beta-lactamases, TEM-1 and ROB-1, have been observed in Haemophilus influenzae, while four different TEM but no ROB enzymes have been found in Haemophilus parainfluenzae. In order to investigate the mechanisms behind the dissemination of small beta-lactamase-encoding plasmids in H. influenzae and H. parainfluenzae, we assessed the fitness cost of three TEM-1- (pPN223, pA1209, pA1606), one TEM-15- (pSF3) and one ROB-1-bearing (pB1000) plasmid when expressed in either bacterial species. All plasmids were stable in H. influenzae and H. parainfluenzae except pB1000, which showed on average (sample mean) 76% curing in H. parainfluenzae after 5  days of subculture. Competition assays between isogenic strains with and without plasmid showed no competitive disadvantage of pPN223 and pA1606 in H. influenzae, or of pA1209 in H. parainfluenzae. In contrast, pSF3 and pB1000 were associated with significant competitive disadvantages in both species. Some of the competitive disadvantages may be related to differences in plasmid copy number and mRNA expression of the beta-lactamase genes, as revealed by quantitative PCR analysis. In conclusion, plasmids encoding TEM beta-lactamases isolated from H. influenzae and H. parainfluenzae can be stably transferred between species. The fast curing of pB1000 in H. parainfluenzae observed in this study correlates to the fact that ROB-1 has never been reported for this species. TEM-1-encoding plasmids are associated with the lowest level of fitness cost, but different TEM-1 plasmids confer different levels of fitness cost on the two hosts.


Assuntos
Proteínas de Bactérias/metabolismo , Haemophilus influenzae/enzimologia , Haemophilus parainfluenzae/enzimologia , Plasmídeos/genética , beta-Lactamases/metabolismo , Proteínas de Bactérias/genética , Haemophilus influenzae/genética , Haemophilus parainfluenzae/genética , Plasmídeos/metabolismo , beta-Lactamases/genética
12.
Microbiology (Reading) ; 161(6): 1182-8, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25794502

RESUMO

The newly described species Haemophilus sputorum has been cultured from the upper respiratory tract of humans and appears to have little pathogenic potential. The species encodes a capsular biosynthesis locus of approximately 12  kb composed of three distinct regions. Region I and III genes, involved in export and processing of the capsular material, show high similarity to the corresponding genes in capsulate lineages of the pathogenic species Haemophilus influenzae; indeed, standard bexA and bexB PCRs for detection of capsulated strains of H. influenzae give positive results with strains of H. sputorum. Three ORFs are present in region II of the sequenced strain of H. sputorum, of which a putative phosphotransferase showed homology with corresponding genes from H. influenzae serotype c and f. Phylogenetic analysis of housekeeping genes from 24 Pasteurellaceae species showed that H. sputorum was only distantly related to H. influenzae. In contrast to H. influenzae, the capsule locus in H. sputorum is not associated with transposases or other transposable elements. Our data suggest that the capsule locus of capsulate lineages of H. influenzae may have been recruited relatively recently from the commensal species H. sputorum by horizontal gene transfer.


Assuntos
Cápsulas Bacterianas/genética , Ordem dos Genes , Transferência Genética Horizontal , Loci Gênicos , Haemophilus/genética , Redes e Vias Metabólicas/genética , Sintenia , Evolução Molecular , Genes Essenciais , Infecções por Haemophilus/microbiologia , Humanos , Fases de Leitura Aberta , Filogenia , Reação em Cadeia da Polimerase , Infecções Respiratórias/microbiologia , Análise de Sequência de DNA , Homologia de Sequência
13.
J Clin Microbiol ; 53(12): 3773-8, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26378279

RESUMO

Nonhemolytic variants of Haemophilus haemolyticus are difficult to differentiate from Haemophilus influenzae despite a wide difference in pathogenic potential. A previous investigation characterized a challenging set of 60 clinical strains using multiple PCRs for marker genes and described strains that could not be unequivocally identified as either species. We have analyzed the same set of strains by multilocus sequence analysis (MLSA) and near-full-length 16S rRNA gene sequencing. MLSA unambiguously allocated all study strains to either of the two species, while identification by 16S rRNA sequence was inconclusive for three strains. Notably, the two methods yielded conflicting identifications for two strains. Most of the "fuzzy species" strains were identified as H. influenzae that had undergone complete deletion of the fucose operon. Such strains, which are untypeable by the H. influenzae multilocus sequence type (MLST) scheme, have sporadically been reported and predominantly belong to a single branch of H. influenzae MLSA phylogenetic group II. We also found evidence of interspecies recombination between H. influenzae and H. haemolyticus within the 16S rRNA genes. Establishing an accurate method for rapid and inexpensive identification of H. influenzae is important for disease surveillance and treatment.


Assuntos
Fucose/metabolismo , Haemophilus/classificação , Haemophilus/genética , Redes e Vias Metabólicas/genética , Tipagem de Sequências Multilocus/métodos , Óperon , Deleção de Sequência , Pré-Escolar , Análise por Conglomerados , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Feminino , Haemophilus/isolamento & purificação , Infecções por Haemophilus/microbiologia , Humanos , Lactente , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
14.
Int J Infect Dis ; 146: 107099, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-38762047

RESUMO

OBJECTIVE: To resolve an exceptional clustering of Cutibacterium avidum prosthetic valve infective endocarditis (IE) at a single heart center. METHODS: During a period of 21 months, three patients experienced C. avidum bacteremia 24-128 days after aortic valve replacement. Operative procedures and electronic prescriptions of antimicrobials were surveyed, and bacterial isolates were genome sequenced. RESULTS: The prosthetic valves were inserted by separate surgical teams. In one case, echocardiographic confirmation of IE was not achieved until 4 months after the first positive blood culture, but the causative agents were irrefutably documented in all cases by culture, or amplification of bacterial deoxyribonucleic acid, from removed prosthetic material. Whole-genome sequencing clustered isolates to a distinctive subgroup of the species but did not suggest inter-patient transmission of isolates. CONCLUSIONS: Despite vigorous sampling of blood and tissue, detection of C. avidum was not unconditional, neither by culture nor polymerase chain reaction test. The causative agent is likely underreported and should be meticulously searched for in culture-negative prosthetic valve endocarditis.


Assuntos
Endocardite Bacteriana , Próteses Valvulares Cardíacas , Infecções Relacionadas à Prótese , Humanos , Endocardite Bacteriana/microbiologia , Endocardite Bacteriana/diagnóstico , Endocardite Bacteriana/tratamento farmacológico , Infecções Relacionadas à Prótese/microbiologia , Infecções Relacionadas à Prótese/diagnóstico , Infecções Relacionadas à Prótese/tratamento farmacológico , Próteses Valvulares Cardíacas/efeitos adversos , Próteses Valvulares Cardíacas/microbiologia , Masculino , Feminino , Idoso , Pessoa de Meia-Idade , Antibacterianos/uso terapêutico , Bacteriemia/microbiologia , Bacteriemia/diagnóstico
15.
Int J Med Microbiol ; 303(5): 267-9, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23742822

RESUMO

A patient with cystic fibrosis became chronically colonised with an unusual non-fermenting Gram-negative rod that could be cultured on Burkholderia cepacia selective agar. Phenotypic characterisation by VITEK-2 suggested identification as Elizabethkingia meningoseptica, however 16S rRNA gene sequencing revealed it belonged to a putative novel species of genus Dyella. Thirty months after the initial detection, the patient produced a high level of precipitating antibodies against the bacterium.


Assuntos
Portador Sadio/microbiologia , Fibrose Cística/complicações , Infecções por Bactérias Gram-Negativas/microbiologia , Xanthomonadaceae/imunologia , Anticorpos Antibacterianos/sangue , Técnicas de Tipagem Bacteriana , Portador Sadio/imunologia , Análise por Conglomerados , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Infecções por Bactérias Gram-Negativas/imunologia , Humanos , Dados de Sequência Molecular , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Xanthomonadaceae/classificação , Xanthomonadaceae/crescimento & desenvolvimento , Xanthomonadaceae/isolamento & purificação
16.
Pathogens ; 12(11)2023 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-38003810

RESUMO

Pregnancy is associated with a 5-26 times increased risk of invasive Haemophilus influenzae infection and subsequent adverse pregnancy outcomes. Incidence rate and outcome are published in some regions, but the characterisation of bacterial isolates is limited. We performed comparative genomic analyses of isolates from 12 pregnancy-associated cases, cultured from maternal bacteraemia in pregnancy (nine), postpartum bacteraemia (one), neonatal bacteraemia (one), and placental tissue (one). In two bacteraemia cases, identical isolates were also cultured from cervical swabs. Eight cases occurred early in pregnancy (gestational week 7-26), and seven of them resulted in miscarriage or neonatal death. All bacterial genomes were devoid of capsule loci, and they were evenly distributed in the major phylogenetic group I of the species. The conspicuous tropism of H. influenzae for pregnancy and placental tissue is associated with the species rather than specific clonal subtypes.

17.
Antimicrob Agents Chemother ; 56(9): 4958-60, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22733069

RESUMO

TEM-1 is the dominant ß-lactamase of Haemophilus influenzae and can be located on small plasmids. Three distinct plasmids with sizes from 4,304 to 5,646 nucleotides (nt) were characterized: pA1606, pA1209, and pPN223. In addition to TEM-1 and a replication enzyme of the Rep 3 superfamily, pA1606 carries a Tn3 resolvase gene and pA1606 and pA1209 carry an open reading frame (ORF) similar to a plasmid recombination enzyme gene described in Gram-positive bacteria. The plasmids transformed strain Rd to the ampicillin-resistant phenotype.


Assuntos
Haemophilus influenzae/genética , Plasmídeos , Resistência beta-Lactâmica/genética , beta-Lactamases/genética , Ampicilina/farmacologia , Sequência de Bases , Haemophilus influenzae/isolamento & purificação , Testes de Sensibilidade Microbiana , Dados de Sequência Molecular , Fases de Leitura Aberta , RNA Polimerase Dependente de RNA/genética , Recombinases/genética , Transformação Bacteriana , Transposon Resolvases/genética , beta-Lactamas/farmacologia
18.
J Clin Microbiol ; 50(8): 2688-94, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22675125

RESUMO

A multilocus sequence analysis (MLSA) scheme was developed for characterization of strains and species from the genus Achromobacter, which are increasingly recovered from patients with cystic fibrosis (CF). Five conserved housekeeping genes were selected for the MLSA, which was applied to a diverse collection of 77 strains originating from Europe, Asia, and South America and including type strains of the seven recognized Achromobacter species, six environmental strains, eight non-CF clinical strains, and 56 CF clinical strains. The discriminatory power of MLSA, based on 2,098 nucleotides (nt), was much superior to a 16S rRNA gene comparison based on 1,309 nt. Congruence was observed between single-gene trees and a concatenated gene tree. MLSA differentiated all seven current Achromobacter species and also demonstrated the presence of at least four novel potential species within the genus. CF isolates were predominantly Achromobacter xylosoxidans (64%), an undescribed Achromobacter species (18%), and Achromobacter ruhlandii (7%). A clone of Achromobacter, which has spread among patients from Danish CF centers in Aarhus and Copenhagen, was identified as Achromobacter ruhlandii. MLSA facilitates the specific identification of isolates of Achromobacter necessary for describing their role in clinical infections.


Assuntos
Achromobacter/classificação , Achromobacter/genética , Fibrose Cística/complicações , Infecções por Bactérias Gram-Negativas/diagnóstico , Infecções por Bactérias Gram-Negativas/microbiologia , Tipagem de Sequências Multilocus , Achromobacter/isolamento & purificação , Ásia , Análise por Conglomerados , Microbiologia Ambiental , Europa (Continente) , Genótipo , Humanos , Dados de Sequência Molecular , América do Sul
19.
J Antimicrob Chemother ; 67(6): 1401-4, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22389455

RESUMO

OBJECTIVES: EUCAST has recently authorized a new disc diffusion test for routine antimicrobial susceptibility testing of Haemophilus influenzae, calibrated to EUCAST MIC breakpoints. We investigated whether disc diffusion testing as recommended by EUCAST could discriminate strains of H. influenzae carrying the N526K substitution in penicillin-binding protein 3 from the wild-type population. METHODS: A total of 170 recent clinical isolates, genetically characterized for the presence of acquired and mutational resistance mechanisms, were tested by disc diffusion of ß-lactam antibiotics on supplemented Mueller-Hinton agar. Tentative epidemiological breakpoint values for the presence of the N526K substitution were suggested for various ß-lactams, and the performances were calculated. RESULTS: Epidemiological cut-off values of 19/20 mm for ampicillin (2 µg) and 11/12 mm for benzylpenicillin (1 U) accurately categorized 96% of the study strains, and outperformed cephalosporin-containing discs in the discrimination of mutational resistance in ß-lactamase-non-producing isolates. Current EUCAST interpretative criteria for the categorization of clinical resistance showed concordance between resistance rates based on MIC and zone diameter breakpoints for both ampicillin and cefuroxime, but categorization of individual isolates was not consistent. CONCLUSIONS: Disc diffusion testing of H. influenzae accurately identified ß-lactamase-non-producing isolates with the N526K substitution by use of discs containing low amounts of penicillins. Cephalosporin-containing discs could detect mutational resistance in ß-lactamase-producing isolates, but performed with reduced specificity.


Assuntos
Haemophilus influenzae/efeitos dos fármacos , Haemophilus influenzae/enzimologia , Mutação de Sentido Incorreto , Proteínas de Ligação às Penicilinas/genética , Proteínas de Ligação às Penicilinas/metabolismo , Resistência beta-Lactâmica , Antibacterianos/farmacologia , Infecções por Haemophilus/microbiologia , Haemophilus influenzae/genética , Haemophilus influenzae/isolamento & purificação , Humanos , Testes de Sensibilidade Microbiana/métodos , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , beta-Lactamas/farmacologia
20.
Int J Med Microbiol ; 302(2): 78-83, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22336150

RESUMO

Haemolytic Haemophilus strains with no requirement for X factor are regularly isolated from sputum and throat swabs and occasionally from invasive infections, but the classification of such strains is not clear. We characterized 56 strains with a phenotype concordant with Haemophilus parahaemolyticus (V, but not X factor-dependent; urease-positive; tryptophanase-negative; ornithine decarboxylase-negative) by extended phenotypic testing and 16S rRNA gene sequencing. In addition, 31 of the strains and representative type strains were investigated by multilocus sequence analysis based on 3 housekeeping gene fragments. Most strains could be assigned to H. parahaemolyticus and were characterized by expression of IgA1 protease and a negative test for ß-galactosidase. Isolation of H. parahaemolyticus from various infections and its absence among more than 300 commensal Haemophilus isolates suggests a pathogenic potential of this organism. The majority of haemolytic strains with ß-galactosidase activity did not cluster with the type strain of H. paraphrohaemolyticus, but constituted a distinct and coherent novel taxon. Ten strains of this new taxon proved to be genetically and phenotypically homogeneous. Few biochemical characters discriminate the new taxon from related Haemophilus species, but identification is easily accomplished by routine matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Genetic, biochemical, and spectrometry data show that the taxon merits recognition as a novel species of Haemophilus. The name Haemophilus sputorum is proposed, with CCUG 13788(T) (=DSM 24472(T)=NCTC 13537(T)) as the type strain.


Assuntos
Haemophilus/classificação , Haemophilus/genética , Haemophilus/isolamento & purificação , Humanos , Espectrometria de Massas , Dados de Sequência Molecular , Fenótipo , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA