RESUMO
Carbapenem-resistant Klebsiella pneumoniae is a common cause of healthcare-related infections, and it is widespread in hospitals and diverse environments with potentially serious public health implications. Herein, we have reported the isolation and characterization of an environmental Brazilian Klebsiella carbapenemase (BKC-1)-producing K. pneumoniae strain (IEC1205) isolated in 2018 from a river in the Amazon region, Brazil. Antimicrobial susceptibility of this strain was evaluated by broth microdilution and demonstrated resistance to several antibiotics including ß-lactams, aminoglycosides, fluoroquinolones, and polymyxins. It has an extensively drug-resistant phenotype. Genomic analysis revealed that IEC1205 belonged to sequence type 11, clonal complex 258 and the presence of blaBKC-1 and two other ß-lactamase-encoding genes (blaCTX-M-15 and blaSHV-11). The predicted virulence was associated with biofilm formation-related genes, a type VI secretion system, siderophore production, and type I and II fimbriae formation. We have identified an IncQ1 plasmid, named pIEC1205, harboring blaBKC-1 with high similarity to previously described plasmids carrying blaBKC-1 and blaBKC-2 genes. To our knowledge, this is the first report of an environmental BKC-1-producing K. pneumoniae strain.
Assuntos
Infecções por Klebsiella , Sistemas de Secreção Tipo VI , Aminoglicosídeos , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Brasil , Carbapenêmicos , Células Clonais , Farmacorresistência Bacteriana Múltipla/genética , Fluoroquinolonas , Genômica , Humanos , Klebsiella/genética , Klebsiella pneumoniae/genética , Testes de Sensibilidade Microbiana , Plasmídeos , Polimixinas , Rios , Sideróforos , beta-Lactamases/genética , beta-LactamasRESUMO
This study aimed to verify the role of ISKpn23 in the expression and mobilization of blaBKC-1 and aph(3')-VIi. Five constructs related to the natural blaBKC-1 genetic background in plasmid p60136 were made and submitted for antimicrobial susceptibility testing and quantitative reverse transcription-PCR. Transposition of ISKpn23-blaBKC-1 was investigated using transposition assays involving a 9.7-kb nonconjugative plasmid carrying blaBKC-1 (p60136) and a transfer-proficient plasmid (pOX38-Gen). The presence of ISKpn23 had a crucial role in blaBKC-1 expression, resulting in increased ß-lactam MICs. While we detected mobilization of p60136 by the pOX38-Gen plasmid, transposition of ISKpn23-blaBKC-1 was not observed.
Assuntos
Proteínas de Bactérias , beta-Lactamases , Proteínas de Bactérias/genética , Conjugação Genética , Testes de Sensibilidade Microbiana , Plasmídeos/genética , beta-Lactamases/genética , beta-Lactamases/metabolismoRESUMO
We sequenced 13 Neisseria gonorrhoeae isolates exhibiting distinct susceptibility profiles and which were recovered over 12 years in the metropolitan region of São Paulo, Brazil. Whole Genome Sequencing (WGS) was performed on an Illumina MiSeq™ 2 × 300 bp paired-end reads. Bioinformatics analyses were carried out using CGE, PATRIC, and BLAST databases for manual curation of obtained genomes. Multilocus sequence typing (MLST) analysis identified seven STs, namely ST1580, ST1590, ST1901, ST1902, ST8161, ST9363, and ST15640. Moreover, a diversity of mutations was observed in MtrR/G45D-A39T, PIB/G120K-A121S, and PBP1/L421P. Mutations associated with sulfonamides (DHPS/R228S) and rifampicin (RNAP/H552N) were also detected, as well as tetracycline resistance determinants, namely rpsJ/V57M and tet(M). The results presented herein can contribute to the knowledge of N. gonorrhoeae strains circulating in Sao Paulo, Brazil.
Assuntos
Gonorreia , Neisseria gonorrhoeae , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Brasil , Ciprofloxacina/farmacologia , Farmacorresistência Bacteriana/genética , Gonorreia/tratamento farmacológico , Humanos , Testes de Sensibilidade Microbiana , Tipagem de Sequências Multilocus , Neisseria gonorrhoeae/genéticaRESUMO
We characterized a multidrug-resistant (MDR) Enterobacter spp. isolate highlighting the genetic aspects of the antimicrobial resistance genes. An Enterobacter spp. isolate (Ec61) was recovered in 2014 from a transtracheal aspirate sample from a patient admitted to a Brazilian tertiary hospital and submitted to further microbiological and genomic characterization. Ec61 was identified as Enterobacter hormaechei subsp. xiangfangensis strain ST451, showing an MDR profile and the presence of genes codifying the new ß-lactamase variants BKC-2 and ACT-84 and the mobile colistin resistance gene mcr-9.1.
Assuntos
Colistina , Enterobacter , Antibacterianos/farmacologia , Brasil , Colistina/farmacologia , Enterobacter/genética , Humanos , Plasmídeos , beta-Lactamases/genéticaRESUMO
OBJECTIVES: Carbapenem resistance in Klebsiella pneumoniae is a major clinical challenge. Aminoglycosides remain an important asset in the current therapeutic arsenal to treat these infections. We examined aminoglycoside resistance phenotypes and genomics in a collection of 100 invasive KPC-producing K. pneumoniae isolates sequentially collected in a Brazilian tertiary hospital between 2014 and 2016. METHODS: Aminoglycoside susceptibility testing was performed. We used a combined long-read (MinION) and short-read (Illumina) whole-genome sequencing strategy to provide a genomic picture of aminoglycoside resistance genes, with particular emphasis on 16S rRNA methyltransferases and related plasmids. RESULTS: 68% of the strains were resistant to gentamicin and 42% to amikacin, with 35% resistant to both of these commonly used aminoglycosides. We identified the 16S rRNA methyltransferase gene rmtB in 30% of these isolates: 97% (29/30) belonged to sequence type 258 (ST258) and a single isolate to the emergent ST16 clone. In ST258 and ST16 the rmtB gene was located on large IncC plasmids of 177 kb and 174 kb, respectively, highly similar to a plasmid previously identified in Proteus mirabilis in the same hospital. Moreover, 99% of the isolates remained susceptible to the veterinary-approved drug apramycin, currently under clinical development for human medicine. CONCLUSION: Such findings in geographically and temporally related isolates suggest a combination of vertical clonal spread as well as horizontal interspecies and intraspecies plasmid transfer. This broad rmtB dissemination in an endemic setting for KPC-producing clones is worrisome since it provides resistance to most clinically available aminoglycosides, including the novel aminoglycoside-modifying enzyme-resistant plazomicin.
Assuntos
Klebsiella pneumoniae , beta-Lactamases , Proteínas de Bactérias/genética , Brasil , Humanos , Interleucinas , Klebsiella pneumoniae/genética , Metiltransferases , Testes de Sensibilidade Microbiana , Plasmídeos/genética , RNA Ribossômico 16S/genética , Sisomicina/análogos & derivados , beta-Lactamases/genéticaRESUMO
We characterized by whole-genome sequencing (WGS) six carbapenem-resistant Acinetobacter baumannii strains isolated from a Brazilian tertiary hospital during a 14-day period. The ISAba1-blaOXA-23 structure was found in the chromosome of five isolates, whereas blaOXA-72 was inserted in a 16.6-kb plasmid in two isolates. The presence of ISAba1-blaADC-like justified the high broad-spectrum cephalosporins minimal inhibitory concentrations (MICs) (MIC50, > 512 mg/L) verified in all isolates. Only minocycline (MIC50, ≤ 0.5 µg/mL), polymyxin B (MIC50, 0.5 µg/mL), and tigecycline (MIC50, 0.5 µg/mL) were in vitro active against such isolates. A diversity of other antimicrobial resistance determinants (aph(3')-VIa, aadA1, aac(3')-IIa, strA, strB, sul2, drfA1, mph(E), msr(E), tetB, and floR) was also observed, which may confer resistance to at last six distinct antimicrobial classes. Four distinct pulsed-field gel electrophoresis (PFGE) profiles were observed during the study period, which belonged to ST79/ST258 (n = 2; IC5), ST25/ST229 (n = 2; IC7), ST1 (n = 1; IC1), and ST162/ST235 (n = 1; IC4). Although the ST1 isolate that carried blaOXA-23 and blaOXA-72 was introduced in this hospital setting by a transferred patient, two clonally related ST79/ST258 isolates carrying either one of these carbapenemase encoding genes were recovered from two patients who were hospitalized within the same period of time in the same hospital unit. Finally, a good correlation between PFGE/MLST, blaOXA-51 variant, and single nucleotide polymorphisms was also observed. Here we demonstrated that distinct extensively drug-resistant A. baumannii clones can circulate in the same hospital setting during a short time period, illustrating a very complex epidemiological scenario for this priority pathogen.
Assuntos
Acinetobacter baumannii/genética , Antibacterianos/farmacologia , Farmacorresistência Bacteriana Múltipla/genética , beta-Lactamases/genética , Proteínas de Bactérias/genética , Brasil/epidemiologia , Eletroforese em Gel de Campo Pulsado , Genes Bacterianos/genética , Humanos , Testes de Sensibilidade Microbiana , Tipagem de Sequências Multilocus , Plasmídeos , Polimorfismo de Nucleotídeo Único , Centros de Atenção Terciária , Sequenciamento Completo do GenomaRESUMO
ABSTRACT Due to the emergence of multi-drug resistant bacteria, and the evident limitation in therapeutic options, alternatives to combat bacterial infections have been sought. One of these is phage therapy, which is the use of bacterial viruses to kill pathogenic bacteria responsible for the infection. These viruses called bacteriophages are very abundant organisms in the world and are harmless to humans. There are several advantages in using phage therapy, especially against multi-drug resistant pathogens, which tend to be dominated by individual strains. The advantages include fewer collateral effects such as lower disturbance of gut microbiota and less antimicrobials consumption, which itself leads to reducing antibiotic resistance rates. Unfortunately, few clinical studies have been initiated in Brazil and this area is little explored in our country. This manuscript describes clinical evidence of successful phage utilization on pathogens considered a threat in Brazil, highlighting the benefits of a possible phage utilization as an important tool to combat antimicrobial resistance in our country.
RESUMO
Due to the emergence of multi-drug resistant bacteria, and the evident limitation in therapeutic options, alternatives to combat bacterial infections have been sought. One of these is phage therapy, which is the use of bacterial viruses to kill pathogenic bacteria responsible for the infection. These viruses called bacteriophages are very abundant organisms in the world and are harmless to humans. There are several advantages in using phage therapy, especially against multi-drug resistant pathogens, which tend to be dominated by individual strains. The advantages include fewer collateral effects such as lower disturbance of gut microbiota and less antimicrobials consumption, which itself leads to reducing antibiotic resistance rates. Unfortunately, few clinical studies have been initiated in Brazil and this area is little explored in our country. This manuscript describes clinical evidence of successful phage utilization on pathogens considered a threat in Brazil, highlighting the benefits of a possible phage utilization as an important tool to combat antimicrobial resistance in our country.
Assuntos
Bacteriófagos , Farmacorresistência Bacteriana/genética , Terapia por Fagos , Antibacterianos , Infecções Bacterianas , Brasil , HumanosRESUMO
Carbapenem resistance in Acinetobacter baumannii is a public health issue globally, mainly due to the production of carbapenem hydrolyzing class D ß-lactamases (CHDLs). In Brazil, OXA-23 and OXA-143 CHDLs have been prevalent in A. baumannii from clinical settings, with some OXA-23 reports in the environmental samples, whereas OXA-72 has begun to be increasingly reported. This study aims to perform the genomic and microbiological characterization of carbapenem-resistant A. baumannii isolates recovered from migratory birds and captive birds inhabiting a lake within a Brazilian Zoo. Four hundred and eighty-one gram-negative bacilli were recovered from choanal and cloacal swabs obtained from 50 migratory birds and 37 captive birds present at the zoo's lake between July and August of 2012. Among all GNB, nine OXA-72-producing A. baumannii were detected from the microbiota of four migratory and five captive aquatic birds. The OXA-72-producing A. baumannii isolates were submitted to antimicrobial susceptibility test and PFGE, exhibiting a multidrug-resistant profile and clonal relatedness with OXA-72-positive human isolates circulating for eighteen years in a hospital setting. MLST, plasmid analysis and whole-genome sequencing revealed which all carbapenem-resistant A. baumannii from bird and human hosts belonged to clonal complex 79, and harboured a small plasmid (â16.6-kb in size), named pAC1-BRL, which carried blaOXA-72 gene, macrolide resistance genes msrE and mphE, and the toxin-antitoxin system AbkAB. To determine the impact of pAC1-BRL acquisition in the the capacity of a microorganism to survive in a competitive environment (in the following called fitness), the laboratory strain A. baumannii ATCC 19606 was used in the fitness experiments and suggested an increase of its relative fitness after the pAC1-BRL acquisition. In summary, the detection of OXA-72-producing A. baumannii strains belonging to CC79 in aquatic birds is a piece of epidemiological evidence demonstrating that dissemination of high-risk bacteria is extending beyond the hospital.
Assuntos
Infecções por Acinetobacter , Acinetobacter baumannii/efeitos dos fármacos , Animais , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Aves , Brasil , Carbapenêmicos , Farmacorresistência Bacteriana/efeitos dos fármacos , Humanos , Macrolídeos , Testes de Sensibilidade Microbiana , Tipagem de Sequências Multilocus , beta-LactamasesRESUMO
We characterize by whole-plasmid-sequence (WPS) two-plasmid-borne blaOXA-58 obtained from Acinetobacter seifertii (Asp-1069) and A. baumannii (Acb-45063) clinical strains recovered 17 years apart from distinct Brazilian regions. Multilocus sequence type (MLST) analysis showed that the Asp-1069 and Acb-45063 strains belong to ST551 and ST15/CC15, respectively. WPS analysis demonstrated that blaOXA-58 was located in two distinct plasmids named pAs1069_a (24,672 bp/44 open reading frames [ORFs]) and pAb45063_b (19,808 bp/24 ORFs), which belong to the GR8/GR23 (repAci23) and GR4 (repAci4) incompatibility groups, respectively. The genetic environments surrounding blaOXA-58 revealed that it was flanked by two intact ISAba3 copies on pAb45063_b, which differed from pAs1069_a. In the latter, the upstream ISAba3 copy was truncated by insertion of ISAba825 element. Although Re27-specific recombination sites were found adjacent to ISAba3-blaOXA-58-ISAba3 arrangement on pAb45063_b, such structures were absent on pAs1069_a. The conserved ISAba125-araC1-lysE arrangement was disrupted by TnaphA6 harboring the aminoglycosides resistance gene aphA6 on pAs1069_a, while an IS26-blaTEM-1-aac(3)-IIa-IS26 genetic structure was found upstream from ISAba3-blaOXA-58-ISAba3 on pAb45063_b. Other two plasmids, pAb45063_a (183,767 bp/209 ORFs) and pAs1069_b (13,129 bp/14 ORFs), were also found in the OXA-58-producing Acinetobacter species strains, harboring the strA and strB genes and the sul2 gene, which confer resistance to streptomycin and sulfonamides, respectively. The plasmid-mediated virulence factors corresponding to genes tonB, spl, glmM, ppa, sulP, and map were found in both strains, as well distinct toxin-antitoxin system-encoding genes stbD and relE (pAs1069_a), brnT and brnA (pAb45063_b), and xreE (pAb45063_a). Although infrequently reported in Brazil, plasmid-borne blaOXA-58 showed a complex and diverse genetic backbone that confers stability in different Acinetobacter species that have been isolated from nosocomial settings over time.IMPORTANCE Although the blaOXA-58 gene has been infrequently described in Brazil, contrasting with other bordering South American countries, we verified the maintenance of this resistance determinant over time among carbapenem-resistant Acinetobacter species isolates, not only in nosocomial settings but also in the environment. In addition, to the best of our knowledge, this is the first study to have used WPS analysis to evaluate the genetic surroundings of blaOXA-58 in Brazil. Moreover, the A. seifertii and A. baumannii clinical strains evaluated in this study were recovered 17 years apart in hospitals located in distinct Brazilian geographic regions.
Assuntos
Acinetobacter/genética , Plasmídeos/genética , beta-Lactamases/genética , Acinetobacter/efeitos dos fármacos , Acinetobacter/enzimologia , Infecções por Acinetobacter/microbiologia , Antibacterianos/farmacologia , Técnicas de Tipagem Bacteriana , Brasil , Carbapenêmicos/farmacologia , DNA Bacteriano/genética , Humanos , Testes de Sensibilidade Microbiana , Tipagem de Sequências Multilocus , Fatores de Virulência/genéticaRESUMO
In this article, we report a case series of patients with infections caused by Enterobacteriales coresistant to carbapenems and polymyxins who were treated with ceftazidime/avibactam (CAZ-AVI) salvage therapy on a compassionate-use protocol. We enrolled 29 adult patients in 3 centers that had an infection due to a resistant microorganism and for whom the treatments available were considered ineffective, treated them with CAZ-AVI, and assessed clinical and microbiological cure at the end of treatment and all-cause mortality at 14 days and 30 days. The antimicrobial susceptibility profile was determined using broth microdilution, and total genomic DNA was sequenced. Twelve (41.4%) patients had bacteremia, and 48.3% (14/29) of the infections were treated with combination therapy. All strains were producers of KPC-2 and were susceptible to CAZ-AVI (MIC90, 1 µg/ml). Clinical success was high (24/29 [82.7%; 95% confidence interval, 64.2 to 94.2%]), even for the bacteremic cases (75%). The 14-day and 30-day mortality rates were 9/29 (31%) and 15/29 (51.7%), respectively. The 14-day mortality rate for pneumonia was the same as that for bloodstream infections (33.3%) and although not significant, we found that patients with renal impairment that received adjusted doses of CAZ-AVI had high mortality (4/9 [44%]; P = 0.22). We concluded that CAZ-AVI is an option for the treatment of severe infections due to difficult-to-treat drug-resistant Enterobacteriales.
Assuntos
Antibacterianos/uso terapêutico , Compostos Azabicíclicos/uso terapêutico , Bacteriemia/tratamento farmacológico , Ceftazidima/uso terapêutico , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Infecções por Enterobacteriaceae/tratamento farmacológico , Pneumonia Bacteriana/tratamento farmacológico , Terapia de Salvação/métodos , Adulto , Bacteriemia/microbiologia , Bacteriemia/mortalidade , Bacteriemia/patologia , Carbapenêmicos/uso terapêutico , Combinação de Medicamentos , Farmacorresistência Bacteriana Múltipla/genética , Enterobacteriaceae/efeitos dos fármacos , Enterobacteriaceae/enzimologia , Enterobacteriaceae/crescimento & desenvolvimento , Enterobacteriaceae/patogenicidade , Infecções por Enterobacteriaceae/microbiologia , Infecções por Enterobacteriaceae/mortalidade , Infecções por Enterobacteriaceae/patologia , Feminino , Expressão Gênica , Humanos , Masculino , Testes de Sensibilidade Microbiana , Pessoa de Meia-Idade , Pneumonia Bacteriana/microbiologia , Pneumonia Bacteriana/mortalidade , Pneumonia Bacteriana/patologia , Polimixinas/uso terapêutico , Estudos Prospectivos , Análise de Sobrevida , beta-Lactamases/genética , beta-Lactamases/metabolismoRESUMO
Nine carbapenem-resistant Acinetobacter baumannii isolates carrying blaOXA-231 and an ISAba1 upstream occAB1 were evaluated. They were clonally related and belonged to ST107. An OXA-143-producing A. baumannii ST107 strain (Ac-148) that did not possess ISAba1 upstream occAB1 was included in the analysis. Reduction in the expression of occAB1 and a 4-fold increase of carbapenem MICs were observed for all isolates, except for the Ac-148 strain, probably due to the presence of ISAba1 upstream occAB1 but in the same transcriptional orientation. We reported an A. baumannii ST107 clone carrying blaOXA-143 that acquired a mutation resulting into blaOXA-231 and mobilized ISAba1 upstream occAB1.
Assuntos
Infecções por Acinetobacter/microbiologia , Acinetobacter baumannii/enzimologia , Acinetobacter baumannii/genética , Proteínas de Bactérias/metabolismo , Elementos de DNA Transponíveis , beta-Lactamases/metabolismo , Acinetobacter baumannii/efeitos dos fármacos , Proteínas de Bactérias/genética , Farmacorresistência Bacteriana Múltipla , Humanos , Testes de Sensibilidade Microbiana , Mutação , beta-Lactamases/genéticaRESUMO
The production of São Paulo metallo-ß-lactamase (SPM-1) is the most common carbapenem resistance mechanism detected among multidrug-resistant Pseudomonas aeruginosa clinical isolates in Brazil. Dissemination of SPM-1-producing P. aeruginosa has been restricted to the nosocomial settings, with sporadic reports of environmental isolates due to contamination by hospital sewage. Herein, we described the detection and molecular characterization of SPM-1-producing P. aeruginosa recovered from the microbiota of migratory birds in Brazil. Three hundred gram-negative bacilli were recovered from cloacal and choanal swabs of Dendrocygna viduata during a surveillance study for detection of carbapenem-resistant isolates. All isolates were identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry. Molecular typing was performed by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing. MICs were determined by agar dilution, except for polymyxin B. Antibiotic resistance genes were detected by polymerase chain reaction (PCR) followed by DNA sequencing. Transcriptional levels of oprD and efflux system encoding genes were also carried out by quantitative real-time PCR. Nine imipenem-resistant P. aeruginosa isolates were recovered with 7 of them carrying blaSPM-1. Additional resistance genes (rmtD-1, blaOXA-56,aacA4, and aac(6')-Ib-cr) were also detected in all 9 isolates. The SPM-1-producing isolates showed high MICs for all ß-lactams, fluoroquinolones, and aminoglycosides, being susceptible only to polymyxin B. Interestingly, all isolates showed the same PFGE pattern and belonged to ST277. Overexpression of MexXY-OprM and MexAB-OprM was observed in those isolates that did not harbor blaSPM-1. Our results suggest that migratory birds might have played a role in the dissemination of SPM-1-producing P. aeruginosa within the Brazilian territory.
Assuntos
Antibacterianos/farmacologia , Doenças das Aves/epidemiologia , Patos/microbiologia , Infecções por Pseudomonas/epidemiologia , Infecções por Pseudomonas/veterinária , Pseudomonas aeruginosa/genética , beta-Lactamases/genética , Migração Animal , Animais , Proteínas da Membrana Bacteriana Externa/biossíntese , Proteínas da Membrana Bacteriana Externa/genética , Proteínas de Bactérias/biossíntese , Proteínas de Bactérias/genética , Doenças das Aves/microbiologia , Aves , Brasil/epidemiologia , Carbapenêmicos/farmacologia , DNA Bacteriano/genética , Farmacorresistência Bacteriana/genética , Eletroforese em Gel de Campo Pulsado , Humanos , Imipenem/farmacologia , Proteínas de Membrana Transportadoras/biossíntese , Proteínas de Membrana Transportadoras/genética , Testes de Sensibilidade Microbiana , Microbiota/efeitos dos fármacos , Microbiota/genética , Tipagem de Sequências Multilocus , Polimixina B/farmacologia , Porinas/genética , Infecções por Pseudomonas/transmissão , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/isolamento & purificação , Pseudomonas aeruginosa/metabolismo , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Resistência beta-Lactâmica/genéticaRESUMO
The emergence and rapid dissemination of colistin-resistant Escherichia coli carrying the plasmid-mediated mcr-1 gene have created an urgent need to develop specific screening methods. In this study, we evaluated four assays based on the inhibition of MCR-1 activity by EDTA: (i) a combined-disk test (CDT) comparing the inhibition zones of colistin and colistin (10 µg) plus EDTA (100 mM); (ii) reduction of colistin MIC (CMR) in the presence of EDTA (80 µg/ml); (iii) a modified rapid polymyxin Nordmann/Poirel test (MPNP); and (iv) alteration of zeta potential (RZP = ZP+EDTA/ZP-EDTA). We obtained encouraging results for the detection of MCR-1 in E. coli isolates recovered from human, food, and animal samples, using the following assay parameters: ≥3 mm difference in the inhibition zones between colistin disks without and with EDTA; ≥4-fold colistin MIC decrease in the presence of EDTA; RZP of ≥2.5; and the absence of metabolic activity and proliferation, indicated by unchanged color of phenol red in the presence of colistin-EDTA, in the MPNP test. In this regard, the CDT, CMR, RZP, and MPNP assays exhibited sensitivities of 96.7, 96.7, 95.1, and 96.7% and specificities of 89.6, 83.3, 100, and 100%, respectively, for detecting MCR-1-positive E. coli Our results demonstrate that inhibition by EDTA and zeta potential assays may provide simple and inexpensive methods for the presumptive detection of MCR-1-producing E. coli isolates in human and veterinary diagnostic laboratories.
Assuntos
Antibacterianos/farmacologia , Colistina/farmacologia , Farmacorresistência Bacteriana , Proteínas de Escherichia coli/análise , Escherichia coli/efeitos dos fármacos , Testes de Sensibilidade Microbiana/métodos , Animais , Quelantes de Cálcio/metabolismo , Ácido Edético/metabolismo , Escherichia coli/genética , Escherichia coli/isolamento & purificação , Infecções por Escherichia coli/microbiologia , Infecções por Escherichia coli/veterinária , Proteínas de Escherichia coli/antagonistas & inibidores , Microbiologia de Alimentos , Humanos , Sensibilidade e EspecificidadeAssuntos
Infecções por Acinetobacter/veterinária , Acinetobacter/efeitos dos fármacos , Acinetobacter/genética , Anseriformes/microbiologia , Proteínas de Bactérias/genética , Farmacorresistência Bacteriana/genética , beta-Lactamases/genética , Acinetobacter/classificação , Acinetobacter/isolamento & purificação , Animais , Antibacterianos/farmacologia , Carbapenêmicos/farmacologia , Lagos/microbiologia , Testes de Sensibilidade Microbiana , beta-Lactamases/classificação , beta-Lactamases/metabolismoRESUMO
Carbapenems represent the mainstay therapy for the treatment of serious P. aeruginosa infections. However, the emergence of carbapenem resistance has jeopardized the clinical use of this important class of compounds. The production of SPM-1 metallo-ß-lactamase has been the most common mechanism of carbapenem resistance identified in P. aeruginosa isolated from Brazilian medical centers. Interestingly, a single SPM-1-producing P. aeruginosa clone belonging to the ST277 has been widely spread within the Brazilian territory. In the current study, we performed a next-generation sequencing of six SPM-1-producing P. aeruginosa ST277 isolates. The core genome contains 5899 coding genes relative to the reference strain P. aeruginosa PAO1. A total of 26 genomic islands were detected in these isolates. We identified remarkable elements inside these genomic islands, such as copies of the blaSPM-1 gene conferring resistance to carbapenems and a type I-C CRISPR-Cas system, which is involved in protection of the chromosome against foreign DNA. In addition, we identified single nucleotide polymorphisms causing amino acid changes in antimicrobial resistance and virulence-related genes. Together, these factors could contribute to the marked resistance and persistence of the SPM-1-producing P. aeruginosa ST277 clone. A comparison of the SPM-1-producing P. aeruginosa ST277 genomes showed that their core genome has a high level nucleotide similarity and synteny conservation. The variability observed was mainly due to acquisition of genomic islands carrying several antibiotic resistance genes.
RESUMO
BACKGROUND: The emergence of multidrug-resistant Klebsiella pneumoniae is a major public health concern. Many K. pneumoniae infections can only be treated when resorting to last-line drugs such as polymyxin B (PB). However, resistance to this antibiotic is also observed, although insufficient information is described on its mode of action as well as the mechanisms used by resistant bacteria to evade its effects. We aimed to study PB resistance and the influence of abiotic stresses in a clinical K. pneumoniae strain using whole transcriptome profiling. RESULTS: We sequenced 12 cDNA libraries of K. pneumoniae Kp13 bacteria, from two biological replicates of the original strain Kp13 (Kp13) and five derivative strains: induced high-level PB resistance in acidic pH (Kp13pH), magnesium deprivation (Kp13Mg), high concentrations of calcium (Kp13Ca) and iron (Kp13Fe), and a control condition with PB (Kp13PolB). Our results show the involvement of multiple regulatory loci that differentially respond to each condition as well as a shared gene expression response elicited by PB treatment, and indicate the participation of two-regulatory components such as ArcA-ArcB, which could be involved in re-routing the K. pneumoniae metabolism following PB treatment. Modules of co-expressed genes could be determined, which correlated to growth in acid stress and PB exposure. We hypothesize that polymyxin B induces metabolic shifts in K. pneumoniae that could relate to surviving against the action of this antibiotic. CONCLUSIONS: We obtained whole transcriptome data for K. pneumoniae under different environmental conditions and PB treatment. Our results supports the notion that the K. pneumoniae response to PB exposure goes beyond damaged membrane reconstruction and involves recruitment of multiple gene modules and intracellular targets.
Assuntos
Antibacterianos/farmacologia , Farmacorresistência Bacteriana Múltipla , Infecções por Klebsiella/microbiologia , Klebsiella pneumoniae/efeitos dos fármacos , Klebsiella pneumoniae/genética , Polimixina B/farmacologia , Sequências Reguladoras de Ácido Nucleico , Transcriptoma , Respiração Celular/efeitos dos fármacos , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Radical Hidroxila/metabolismo , Klebsiella pneumoniae/metabolismo , Modelos Biológicos , Reprodutibilidade dos TestesRESUMO
BKC-1 is a new class A serine carbapenemase that was recently identified in Klebsiella pneumoniae clinical isolates. The principal objective of this study was to evaluate the frequency of blaBKC-1 by testing a collection of Klebsiella isolates. Only 2 of 635 Klebsiella isolates (0.3%) carried blaBKC-1 The two BKC-1-producing isolates belonged to clonal complex 442 and possessed identical pulsed-field gel electrophoresis patterns. The blaBKC-1 gene was inserted into a 10-kb plasmid that was identical to the previously reported plasmid, p60136. The BKC-producing K. pneumoniae isolates presented also possessed other mechanisms for beta-lactam resistance, such as genes encoding extended-spectrum beta-lactamases and mutations in the genes ompK35 and ompK36, encoding the major porins.