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Hypervirulent K. pneumoniae infection has been raising worldwide and is one of the major causes of community-acquired pyogenic liver abscess. We described a case report of pyogenic liver abscess caused by an atypical hypervirulent (non-hypermucoviscous) K. pneumoniae K1 ST23 in a diabetic Asian patient who resided in Mexico. The susceptibility to antimicrobials, pathogenicity, molecular and genomic analysis were determined. A man from Guangdong (China) with a recent diagnosis of diabetes mellitus was admitted to the hospital, and he denied traveling in the last 3 months. A computed tomography revealed a right lobe liver abscess. On the third day after admission a Klebsiella pneumoniae isolate (14652) was obtained. The isolate corresponded to a susceptible K. pneumoniae with capsular type K1 and ST23 (CG23) and exhibited a non-hypermucoviscous phenotype. The isolate 14652 was genetically related to the globally distributed lineage ST23-KL1. This study describes the first case in Mexico of K. pneumoniae capsular type K1 and ST23 with an atypical hypervirulent phenotype.
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The emergence of hypervirulent Klebsiella pneumoniae (hvKP) strains poses a significant threat to public health due to high mortality rates and propensity to cause severe community-acquired infections in healthy individuals. The ability to form biofilms and produce a protective capsule contributes to its enhanced virulence and is a significant challenge to effective antibiotic treatment. Polyphosphate kinase 1 (PPK1) is an enzyme responsible for inorganic polyphosphate synthesis and plays a vital role in regulating various physiological processes in bacteria. In this study, we investigated the impact of polyP metabolism on the biofilm and capsule formation and virulence traits in hvKP using Dictyostelium discoideum amoeba as a model host. We found that the PPK1 null mutant was impaired in biofilm and capsule formation and showed attenuated virulence in D. discoideum compared to the wild-type strain. We performed a proteomic analysis to gain further insights into the underlying molecular mechanism. The results revealed that the PPK1 mutant had a differential expression of proteins involved in capsule synthesis (Wzi-Ugd), biofilm formation (MrkC-D-H), synthesis of the colibactin genotoxin precursor (ClbB), as well as proteins associated with the synthesis and modification of lipid A (ArnB-LpxC-PagP). These proteomic findings corroborate the phenotypic observations and indicate that the PPK1 mutation is associated with impaired biofilm and capsule formation and attenuated virulence in hvKP. Overall, our study highlights the importance of polyP synthesis in regulating extracellular biomolecules and virulence in K. pneumoniae and provides insights into potential therapeutic targets for treating K. pneumoniae infections.
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Dictyostelium , Klebsiella pneumoniae , Humanos , Virulência , Klebsiella pneumoniae/genética , Polifosfatos , Proteômica , BiofilmesRESUMO
The aim of this study was to determine the genotypic diversity of 22 Cryptococcus gattii species complex clinical isolates from Argentina and to place these genotypes within the diversity of clinical, veterinary and environmental isolates from Latin America. Mating type and antifungal susceptibility of the isolates were also determined. By URA5-RFLP, nine isolates were identified as molecular type VGI, 10 as VGII, one as VGIII and two as VGIV. Multilocus sequence typing (MSLT), following the International Society for Human and Animal Mycology (ISHAM) consensus MLST scheme, was used to determine the genotypic diversity. Our results suggest that, in Argentina, VGI isolates have low genetic diversity, while VGII isolates have high genetic diversity. Both isolates identified as VGIV by URA5-RFLP were genotyped by MLST as belonging to the currently named VGVI clade. From all isolates, eight sequence types (STs) were unique for Argentina, while five STs have been reported already in other countries, being of high interest the genotypes ST20 and ST7 since they belong to the subtypes VGIIa and VGIIb, respectively, which are associated with hypervirulent strains responsible for outbreaks in North America. To note, geographical analysis showed that some genotypes may be associated with some regions in Argentina. Most isolates were MATα, but we are reporting one isolate MATa for the first time in the country. Antifungal susceptibility tests showed that itraconazole, voriconazole and posaconazole had high activity against all isolates, while amphotericin B, fluconazole and 5-fluorocytosine were the least active drugs against all studied isolates.
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Criptococose , Cryptococcus gattii , Animais , Humanos , Antifúngicos/farmacologia , Tipagem de Sequências Multilocus , Argentina , Criptococose/microbiologia , GenótipoRESUMO
Infection with Clostridioides difficile (CDI), a common healthcare-associated infection, includes symptoms ranging from mild diarrhea to severe cases of pseudomembranous colitis. Toxin A (TcdA) and toxin B (TcdB) cause cytotoxicity and cellular detachment from intestinal epithelium and are responsible for CDI symptomatology. Approximately 20% of C. difficile strains produce a binary toxin (CDT) encoded by the tcdA and tcdB genes, which is thought to enhance TcdA and TcdB toxicity; however, the role of CDT in CDI remains controversial. Here, we focused on describing the main features of CDT and its impact on the host, clinical relevance, epidemiology, and potential therapeutic approaches.
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Toxinas Bacterianas , Clostridioides difficile , Infecção Hospitalar , Enterocolite Pseudomembranosa , Anticorpos Antibacterianos , Toxinas Bacterianas/genética , Toxinas Bacterianas/toxicidade , Clostridioides difficile/genética , HumanosRESUMO
BACKGROUND Neisseria meningitidis strains belonging to clonal complex 11 is the cause of numerous outbreaks and epidemics in the United States, Canada and Europe, accounting for 49.5% of cases of meningococcal disease caused by serogroup C worldwide. In Brazil, it is the second most frequent clonal complex within this serogroup. The genetic characterisation of cc11/ET-15 variants is important for the epidemiological monitoring of meningococcal disease, through the identification of circulating epidemic clones, to support specific actions of Health Surveillance aiming outbreaks control. OBJECTIVES The objective of this study was to identify features in the genome of cc11/ET-15 clones through whole-genome sequencing (WGS), that differ from cc11/non-ET-15 strains that could explain their virulence. METHODS The whole genome of three cc11/ET-15 representative strains were sequenced with a minimum coverage of 100X with the MiSeq System and compared to the genome of cc11/non-ET-15 strains. RESULTS Genome analysis of cc11/ET-15 variants showed the presence of resistance factors, mobile genetic elements and virulence factors not found in cc11/non-ET-15 strains. MAIN CONCLUSIONS Our results show that these strains carry virulence factors not identified in cc11/non-ET-15 strains, which could explain the high lethality rates attributed to this clone worldwide.
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Group B Streptococcus (GBS) is a leading cause of human neonatal infections and bovine mastitis. We report here the unusual finding of the human-adapted hypervirulent serotype III/ST17 clone in a bovine GBS isolated in 1987 in Brazil. This isolate shared several phenotypic and genotypic characteristics with serotype III/ST17 strains obtained from human sources, including PFGE pattern, pilus genes, lactose fermentation, DNase activity, and antimicrobial susceptibility profile, highlighting the importance of continued tracking of GBS in the One Health scope. The study brings new evidence for the potential interspecies transmission and sheds new light into evolution aspects of the pathogen Group B Streptococcus (GBS) by reporting the occurrence of an ancient bovine GBS isolate belonging to a variant currently known to be exclusively found in human hosts.
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Infecções Estreptocócicas , Streptococcus agalactiae , Animais , Brasil , Bovinos/microbiologia , Células Clonais , Feminino , Humanos , Sorogrupo , Infecções Estreptocócicas/veterinária , Streptococcus agalactiae/genéticaRESUMO
The skin is the largest organ in the human body, acting as a physical and immunological barrier against pathogenic microorganisms. The cutaneous lesions constitute a gateway for microbial contamination that can lead to chronic wounds and other invasive infections. Chronic wounds are considered as serious public health problems due the related social, psychological and economic consequences. The group of bacteria known as ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter sp.) are among the most prevalent bacteria in cutaneous infections. These pathogens have a high level of incidence in hospital environments and several strains present phenotypes of multidrug resistance. In this review, we discuss some important aspects of skin immunology and the involvement of ESKAPE in wound infections. First, we introduce some fundamental aspects of skin physiology and immunology related to cutaneous infections. Following this, the major virulence factors involved in colonization and tissue damage are highlighted, as well as the most frequently detected antimicrobial resistance genes. ESKAPE pathogens express several virulence determinants that overcome the skin's physical and immunological barriers, enabling them to cause severe wound infections. The high ability these bacteria to acquire resistance is alarming, particularly in the hospital settings where immunocompromised individuals are exposed to these pathogens. Knowledge about the virulence and resistance markers of these species is important in order to develop new strategies to detect and treat their associated infections.
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BACKGROUND: The role of myeloid-derived suppressor cells (MDSCs) in patients with severe tuberculosis who suffer from uncontrolled pulmonary inflammation caused by hypervirulent mycobacterial infection remains unclear. METHODS: This issue was addressed using C57BL/6 mice infected with highly virulent Mycobacterium bovis strain MP287/03. RESULTS: CD11b+GR1int population increased in the bone marrow, blood and lungs during advanced disease. Pulmonary CD11b+GR1int (Ly6GintLy6Cint) cells showed granularity similar to neutrophils and expressed immature myeloid cell markers. These immature neutrophils harbored intracellular bacilli and were preferentially located in the alveoli. T-cell suppression occurred concomitantly with CD11b+GR1int cell accumulation in the lungs. Furthermore, lung and bone marrow GR1+ cells suppressed both T-cell proliferation and interferon γ production in vitro. Anti-GR1 therapy given when MDSCs infiltrated the lungs prevented expansion and fusion of primary pulmonary lesions and the development of intragranulomatous caseous necrosis, along with increased mouse survival and partial recovery of T-cell function. Lung bacterial load was reduced by anti-GR1 treatment, but mycobacteria released from the depleted cells proliferated extracellularly in the alveoli, forming cords and clumps. CONCLUSIONS: Granulocytic MDSCs massively infiltrate the lungs during infection with hypervirulent mycobacteria, promoting bacterial growth and the development of inflammatory and necrotic lesions, and are promising targets for host-directed therapies.
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Granulócitos , Pulmão/metabolismo , Mycobacterium bovis , Células Supressoras Mieloides , Tuberculose , Animais , Antígenos Ly , Medula Óssea , Antígeno CD11b , Proliferação de Células , Modelos Animais de Doenças , Granulócitos/imunologia , Imunomodulação , Pulmão/patologia , Camundongos , Camundongos Endogâmicos C57BL , Mycobacterium bovis/patogenicidade , Células Mieloides , Células Supressoras Mieloides/imunologia , Células Supressoras Mieloides/patologia , Neutrófilos , Tuberculose/patologiaRESUMO
The rapid dissemination of extended-spectrum ß-lactamases (ESBLs)-producing Enterobacterales from different spheres worldwide over recent years has become a serious problem in both human and veterinary medicine. CTX-M-3-type ESBL has only been reported on few occasions, and in Brazil the blaCTX-M-3 gene has been identified only once in clinical strains. In this study, we aimed to molecularly characterize a hypermucoviscous (hm), hypervirulent (hv), and extensively drug-resistant (XDR) Klebsiella pneumoniae strain isolated from a lung tissue culture of an infected elephant. The A246 strain belonged to ST2121 and presented hm phenotype, hypervirulence-associated genes, and carried blaCTX-M-3 and plasmid-mediated quinolone resistance genes (qnrB2 and qnrS1) on an IncFII-IncQ1-IncM1 multireplicon plasmid (pA246-CTX-M-3, â¼ 162 kb). A novel genetic context of blaCTX-M-3, in which a 482-bp ISEcp1 was truncated by an IS26, was also harbored by pA246-CTX-M-3. Furthermore, in vivo experiments revealed that the hm/hv A246 strain killed 100 % of the Galleria mellonella larvae at 72 h post-infection. Our findings evidence the intercontinental dissemination of a rare K. pneumoniae ST2121 and the multidrug resistance IncFII-IncQ1-IncM1 plasmid. Therefore, to the best of our knowledge, this is the first report of an XDR K. pneumoniae coproducing CTX-M-3, QnrB2, and QnrS1 isolated from captive wild animals.
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Antibacterianos/farmacologia , Farmacorresistência Bacteriana Múltipla , Elefantes/microbiologia , Infecções por Klebsiella/veterinária , Klebsiella pneumoniae/isolamento & purificação , Klebsiella pneumoniae/patogenicidade , beta-Lactamases/biossíntese , Animais , Animais de Zoológico/microbiologia , Técnicas de Tipagem Bacteriana , Brasil , Escherichia coli/genética , Infecções por Klebsiella/microbiologia , Klebsiella pneumoniae/efeitos dos fármacos , Klebsiella pneumoniae/genética , Larva/microbiologia , Testes de Sensibilidade Microbiana , Mariposas/microbiologia , Tipagem de Sequências Multilocus , Plasmídeos/genética , Quinolonas/farmacologia , Virulência , beta-Lactamases/genética , beta-Lactamas/farmacologiaRESUMO
Klebsiella pneumoniae is one of the most important pathogens related to hospital-acquired infections. The incidence of infections by hypervirulent K. pneumoniae (hvKp), especially community-acquired infections, has been increasing in recent decades. The occurrence of multidrug-resistant (MDR) hvKp has been increasingly reported worldwide decreasing the treatment options, which is a concern. Aquatic environments have been considered a reservoir of MDR pathogens, which contribute to the spread of MDR pathogens. Therefore, this study aimed to characterize MDR-hvKp strains obtained from public aquatic environments using whole genome sequencing in Brazil. Resistome analysis showed ARGs to ß-lactams, quinolones, tetracyclines, sulfonamides, and fosfomycin as well as several metal resistance genes. Virulome analysis showed several virulence genes. Besides, genomic islands, CRISPR and prophage-related sequences were also detected. MLST analysis revealed the presence of two novel sequences types (STs) belonging to different clonal complexes (CCs) [ST4415 (CC515) and ST4416 (CC2654)], and one already described [ST661 (CC661)]. The presence of MDR-hvKp lineages in water sources belonging to STs and CCs associated with humans and animals shows the ability of these pathogens to spread to different aquatic environments. This study reports for the first time two novel STs of MDR-hvKp as well as the presence of a rare ST661 closely related to outbreaks in aquatic environments, and contributes to surveillance studies and MDR-hvKp monitoring worldwide.
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Farmacorresistência Bacteriana/genética , Metais , Poluição da Água/análise , Animais , Antibacterianos , Brasil , Genes Bacterianos , Genômica , Humanos , Infecções por Klebsiella/epidemiologia , Klebsiella pneumoniae/genética , Tipagem de Sequências Multilocus , Virulência/genética , Fatores de Virulência/genética , Sequenciamento Completo do GenomaRESUMO
Klebsiella pneumoniae is a Gram-negative pathogenic bacterium that has the ability to aggregate as biofilm, representing one of the main agents in hospital infections, showing high rates of resistance to antibiotics. The K. pneumoniae biofilm aggregates are composed mainly of extracellular polysaccharides, eDNA and proteins. Besides, biofilms can attach to medical devices, such as endotracheal tubes and catheters, but are most dangerous on body surfaces. Here, we discuss the recent findings about the resistance mechanisms of K. pneumoniae biofilms, including genes and protein involved in 'classic', multidrug-resistant and hypervirulent strains, and also virulence factors. In addition, we also explore new strategies for possible treatment of these biofilms, and recently discovered molecules which may lead to future treatments.
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Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Infecções por Klebsiella/tratamento farmacológico , Klebsiella pneumoniae/efeitos dos fármacos , Fatores de Virulência , Farmacorresistência Bacteriana Múltipla , Humanos , Infecções por Klebsiella/microbiologia , Klebsiella pneumoniae/genética , Percepção de QuorumRESUMO
Aim: Clinical strains of Klebsiella quasipneumoniae subsp. similipneumoniae have been reported worldwide. Multidrug-resistant (MDR) hypermucoviscous (hm)/hypervirulent (hv) lineages have become a global problem for public health worldwide. Therefore, this study aimed to characterize by whole-genome sequencing a MDR-hm/hv K. quasipneumoniae subsp. similipneumoniae SWT10 strain belonging to the new sequence type ST4417 isolated from a sewage treatment plant. Results: The SWT10 strain was recovered from a sewage treatment plant in Brazil and presented the hm and MDR phenotypes. Resistome analysis showed antimicrobial resistance genes associated with resistance to fluoroquinolones, ß-lactams, tetracyclines, trimethoprim, aminoglycosides, sulfonamides, macrolides, and fosfomycin as well as several heavy metal resistance genes. Virulome analysis showed virulence factors related to hv lineages. Multilocus sequence typing analysis revealed the new ST4417, which was grouped in CC1584 by the minimum-spanning tree. Besides, five plasmid incompatibility groups, two prophage-related sequences, and 66 genomic islands were detected. Conclusion: This study reports for the first time the genome sequence of a MDR-hm/hv K. quasipneumoniae subsp. similipneumoniae recovered from the environment, which contributes to a better understanding about these lineages as well as for surveillance studies worldwide.
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Resistência a Múltiplos Medicamentos/genética , Genoma Bacteriano/genética , Klebsiella/genética , Esgotos/microbiologia , Fatores de Virulência/genética , Antibacterianos/farmacologia , Brasil , Genômica/métodos , Infecções por Klebsiella/tratamento farmacológico , Infecções por Klebsiella/microbiologia , Testes de Sensibilidade Microbiana/métodos , Tipagem de Sequências Multilocus/métodos , Plasmídeos/genética , Sequenciamento Completo do Genoma/métodos , beta-Lactamases/genética , beta-Lactamas/metabolismoRESUMO
Streptococcus agalactiae are important pathogenic bacteria that cause severe infections in humans, especially neonates. The mechanism by which ST-17 causes invasive infections than other STs is not well understood. In this study, we sequenced the first genome of a S. agalactiae ST-17 strain isolated in Brazil using the Illumina HiSeq 2500 technology. S. agalactiae GBS90356 ST-17 belongs to the capsular type III and was isolated from a neonatal with a fatal case of meningitis. The genome presented a size of 2.03 Mbp and a Gâ¯+â¯C content of 35.2%. S. agalactiae has 706 genes in its core genome and an open pan-genome with a size of 5.020 genes, suggesting a high genomic plasticity. GIPSy software was used to identify 10 Pathogenicity islands (PAIs) which corresponded to 15% of the genome size. IslandViewer4 corroborated the prediction of six PAIs. The pathogenicity islands showed important virulence factors genes for S. agalactiae e.g. neu, cps, dlt, fbs, cfb, lmb. SignalP detected 20 proteins with signal peptides among the 352 proteins found in PAIs, which 60% were located in the SagPAI_5. SagPAI_2 and 5 were mainly detected in ST-17 strains studied. Moreover, we identified 51 unique genes, 9 recombination regions and a large number of SNPs with an average of 760.3 polymorphisms, which can be related with high genomic plasticity and virulence during host-pathogen interactions. Our results showed implications for pathogenesis, evolution, concept of species and in silico analysis value to understand the epidemiology and genome plasticity of S. agalactiae.
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Genoma Bacteriano , Genômica , Infecções Estreptocócicas/epidemiologia , Infecções Estreptocócicas/microbiologia , Streptococcus agalactiae/classificação , Streptococcus agalactiae/genética , Brasil/epidemiologia , Biologia Computacional/métodos , Genômica/métodos , Humanos , Anotação de Sequência Molecular , Filogenia , Vigilância em Saúde Pública , Streptococcus agalactiae/isolamento & purificação , Streptococcus agalactiae/patogenicidade , Virulência/genética , Fatores de Virulência/genéticaRESUMO
Meningococcal disease is a devastating infection caused by Neisseria meningitidis (meningococcus), and it is classified into serogroups according to its polysaccharide capsule composition. In Brazil, serogroup C is the most frequently responsible for the majority of cases, representing a serious public health challenge. In 2010, the meningococcal serogroup C conjugate vaccine was included in the calendar of the National Immunization Program. We have evaluated 163 meningococcal isolates collected during the pre (2006-2010) and post (2011-2016) vaccination periods. Epidemiological data were determined through Multilocus Sequence Typing (MLST) analysis, vaccine antigens and Bexsero Antigen Sequence Typing (BAST) variant. Clonal complex 103 remains the most prevalent in the country with a high number of serogroup C strains to which CC103 is directly associated. A total of 42 different ST were found. The two most prevalent ST were ST-3780 (CC103) with 38 strains and ST-10781, which was not associated with a CC with nine strains. Allele abcZ-276 was reported among 98% of the strains analyzed and it was not found among other CC103 strains worldwide, makes this allele an important genetic marker for a specific new clone only assigned to Brazilian serogroup C strains, ST-3780. FHbp-25 and NHBA-42 peptides were the most prevalent among isolates in both periods studied. BAST-824 and BAST-3073 have been expressed only in CC103 over the studied years, however, it was not possible to associate a BAST variant to a specific CC. Serogroup C phenotype [P1.22,14-6,36-2: F3-9: ST-3780 (CC103)] was the most prevalent according to the antigenic profiles of circulating strains in Brazil (2007-2016). Our study suggests that CC103 is still a major hypervirulent CC circulating in Brazil and ST-3780 is currently spreading all over the country even after the introduction of MenC in 2010.
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Antígenos de Bactérias/genética , Infecções Meningocócicas/prevenção & controle , Vacinas Meningocócicas/administração & dosagem , Tipagem de Sequências Multilocus/métodos , Neisseria meningitidis Sorogrupo C/classificação , Anticorpos Antibacterianos/metabolismo , Antígenos de Bactérias/imunologia , Brasil , Variação Genética , Humanos , Infecções Meningocócicas/imunologia , Vacinas Meningocócicas/genética , Vacinas Meningocócicas/imunologia , Neisseria meningitidis Sorogrupo C/genética , Neisseria meningitidis Sorogrupo C/imunologia , Neisseria meningitidis Sorogrupo C/isolamento & purificação , Filogenia , Vigilância da População , SorogrupoRESUMO
Hypervirulent Klebsiella pneumoniae have been rarely described in Latin America. This work describes the characterization of hypervirulent K. pneumoniae isolates capsular serotype K2 belonging to sequence types 86 and 380. The assays showed the hypervirulent K. pneumoniae highly virulent, which is determined by the plasmid borne virulence genes. At this time, the hypervirulent K. pneumoniae clinical isolates in Mexico are extensively susceptible to antibiotics.
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Genótipo , Infecções por Klebsiella/microbiologia , Infecções por Klebsiella/patologia , Klebsiella pneumoniae/classificação , Klebsiella pneumoniae/patogenicidade , Sorogrupo , Animais , Adesão Celular , Modelos Animais de Doenças , Feminino , Humanos , Klebsiella pneumoniae/isolamento & purificação , Dose Letal Mediana , Masculino , México , Camundongos Endogâmicos BALB C , Testes de Sensibilidade Microbiana , Modelos Biológicos , Plasmídeos/análise , Fatores de Virulência/genéticaRESUMO
The molecular epidemiology of 38 non-duplicate toxigenic Clostridioides (previously Clostridium) difficile isolates from inpatients from a hospital in Brazil during a 6-year period (2012-2017) were investigated by multilocus sequence typing (MLST) and ribotyping. These isolates were classified into 20 sequence types (ST), six (30%) of which were novel, revealing a high diversity in a single hospital. Classic hypervirulent strains ST1/RT027 and ST11/RT078 were not identified, while ST42 (almost all RT106) was the most common type, being detected in 11 (28.9%) strains. Noteworthy, six (15.8%) isolates were classified into five STs from clade 2, four of which were new ST and RT. Our study suggests that possible hypervirulent strains other than ST1/RT027 might be inadvertently circulating in Brazilian hospitals and highlights the importance of permanent surveillance on circulating strains in a national scale.
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Clostridioides difficile/classificação , Clostridioides difficile/isolamento & purificação , Infecções por Clostridium/epidemiologia , Infecções por Clostridium/microbiologia , Genótipo , Brasil/epidemiologia , Clostridioides difficile/genética , Hospitais Universitários , Pacientes Internados , Epidemiologia Molecular , Tipagem de Sequências Multilocus , RibotipagemRESUMO
Multiresistant and invasive hypervirulent Klebsiella pneumoniae strains have become one of the most urgent bacterial pathogen threats. Recent analyses revealed a high genomic plasticity of this species, harboring a variety of mobile genetic elements associated with virulent strains, encoding proteins of unknown function whose possible role in pathogenesis have not been addressed. K. pneumoniae virulence has been studied mainly in animal models such as mice and pigs, however, practical, financial, ethical and methodological issues limit the use of mammal hosts. Consequently, the development of simple and cost-effective experimental approaches with alternative host models is needed. In this work we described the use of both, the social amoeba and professional phagocyte Dictyostelium discoideum and the fish Danio rerio (zebrafish) as surrogate host models to study K. pneumoniae virulence. We compared three K. pneumoniae clinical isolates evaluating their resistance to phagocytosis, intracellular survival, lethality, intestinal colonization, and innate immune cells recruitment. Optical transparency of both host models permitted studying the infective process in vivo, following the Klebsiella-host interactions through live-cell imaging. We demonstrated that K. pneumoniae RYC492, but not the multiresistant strains 700603 and BAA-1705, is virulent to both host models and elicits a strong immune response. Moreover, this strain showed a high resistance to phagocytosis by D. discoideum, an increased ability to form biofilms and a more prominent and irregular capsule. Besides, the strain 700603 showed the unique ability to replicate inside amoeba cells. Genomic comparison of the K. pneumoniae strains showed that the RYC492 strain has a higher overall content of virulence factors although no specific genes could be linked to its phagocytosis resistance, nor to the intracellular survival observed for the 700603 strain. Our results indicate that both zebrafish and D. discoideum are advantageous host models to study different traits of K. pneumoniae that are associated with virulence.
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Interações Hospedeiro-Patógeno , Infecções por Klebsiella/microbiologia , Klebsiella pneumoniae/fisiologia , Animais , Carga Bacteriana , Comportamento Animal , Biofilmes , Dictyostelium , Resistência à Doença , Interações Hospedeiro-Patógeno/imunologia , Infecções por Klebsiella/imunologia , Klebsiella pneumoniae/patogenicidade , Viabilidade Microbiana , Neutrófilos/imunologia , Neutrófilos/microbiologia , Fagocitose/imunologia , Virulência/genética , Fatores de Virulência/genética , Peixe-ZebraRESUMO
BACKGROUND: Clostridium difficile infection (CDI) leads to the onset of antibiotic-associated diarrhea (AAD) and a wide range of gastrointestinal pathologies. Currently, CDI is one of the most important opportunistic infections at the intrahospital level and an exponential increase in community-acquired infections has been reported. Herein, we evaluated the relationships (at phylogenetic and genetic population structure levels), as well as the molecular toxigenic and antibiotic resistance profiles of a set of isolates established from a case of community acquired-CDI. CASE PRESENTATION: A 30-year-old woman with no history of hospitalization who was exposed to antibiotics (ampicillin/sulbactam and metronidazole) after a cat-bite wound was presented. The patient had a continuous episode of diarrhea; a stool sample was then collected and community acquired-CDI was confirmed by molecular tests and in vitro culture. Seven isolates were established and subsequently subjected to: (i) Multilocus sequence typing, all isolates belonging to ST-1 (associated with hypervirulent strain (027/BI/NAP1); (ii) description of their toxigenic profile: two of the isolates (Gcol.49 and Gcol.91) were positive for the genes coding for the major toxins (tcdA and tcdB) and their negative regulator (tcdC). All isolates were positive for the cdtB gene encoding one of the binary toxin subunits, while only two (Gcol.51 and Gcol.52) were positive for cdtA; and (iii) identification of antibiotic resistance molecular markers, where there was no difference in gyrA or gyrB gene polymorphisms (related to quinolone resistance), but rather at loci presence/absence, being just one isolate negative, whereas the others showed a differential presence of the tet, ermB and Tn916 regions. The former was associated with resistance to tetracycline and the other two for erythromycin/clindamycin. CONCLUSIONS: This case represents the first report of community acquired-CDI in Colombia associated with hypervirulent strains and shows that isolates obtained from a single patient can carry different toxin and antibiotic resistance loci.
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BACKGROUND: Hypervirulent strain of Klebsiella pneumoniae genotype K1 isolates have recently emerged, causing severe pyogenic liver abscess complicated by devastating metastatic infections in humans. METHODS: We describe a short outbreak of the non-human primate (NHP) research center, associated with a hypervirulent K. pneumoniae. The genetic similarity of the strains was evaluated by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) techniques, and virulence encoding genes were detected by polymerase chain reaction (PCR). RESULTS: The isolates were phenotypically like strains causing community-acquired invasive liver abscess syndrome in humans. All strains exhibited identical PFGE patterns and were found to belong to ST23 and presented a hypermucovisity phenotype and possessed magA and rmpA gene. CONCLUSION: This is the first case report of NHPs caused by K. pneumoniae displaying a hypermucoviscosity phenotype and belonging to capsular serotypes K1 and ST23.
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Alouatta , Surtos de Doenças/veterinária , Infecções por Klebsiella/veterinária , Klebsiella pneumoniae/isolamento & purificação , Doenças dos Macacos/epidemiologia , Animais , Brasil/epidemiologia , Eletroforese em Gel de Campo Pulsado/veterinária , Infecções por Klebsiella/diagnóstico , Infecções por Klebsiella/epidemiologia , Infecções por Klebsiella/microbiologia , Klebsiella pneumoniae/classificação , Klebsiella pneumoniae/genética , Masculino , Doenças dos Macacos/diagnóstico , Doenças dos Macacos/microbiologia , Tipagem de Sequências Multilocus/veterinária , Reação em Cadeia da Polimerase/veterináriaRESUMO
A infecção causada por Clostridium difficile (C. difficile), um dos agentes causadores de diarréia aguda e recorrente, tem como principal fator de risco o uso de antimicrobianos. Recentemente, houve um aumento da incidência e da mortalidade desta afecção. Clinicamente, a mesma pode manifestar-se desde um quadro de diarreia aquosa leve até a forma grave de colite pseudomembranosa. O objetivo deste artigo é apontar as mudanças epidemiológicas da infecção pelo C. difficile, além de rever fatores de risco, manifestações clínicas, métodos diagnósticos, tratamento e prevenção desta infecção. O aumento na gravidade da infecção causada pelo C. difficile é relacionado a uma nova cepa hipervirulenta, BI/NAPI/Ribotipo 027, que apresenta maior capacidade de produção de toxinas. Essa nova cepa, mais virulenta, ainda não foi detectada no Brasil, porém como já foi identificada em outros países da América, alerta para a preocupante capacidade de disseminação universal. Essa revisão é baseada em artigos publicados nos últimos 10 anos, utilizando como base de dados o PubMed e o Scielo (Scientific Eletronic Library Online), com as palavras-chave: Epidemiologia, diarreia, Clostridium difficile e cepa hipervirulenta.
Clostridium difficile (C. difficile) is a causative agent of diarrhea and its main risk factor is the use of antimicrobials. Recently, there was an increase in incidence and mortality. Clinical symptoms can manifest from mild watery diarrhea to severe pseudomembranous colitis. The purpose of this article is to make a literature review of C. difficile -associated diarrhea including its recent epidemiological changes. The increase in the severity of infection caused by Clostridium difficile was related to a new hypervirulent strain, BI/NAPI/ribotype 027, with greater capacity for production of toxins, responsible for clinical manifestations. This new strain, more virulent, has not yet been detected in Brazil, but it was already identified in other countries of America, warns the disturbing ability to universal dissemination. This review is based on articles published in the last 10 years, using as database PubMed and Scielo (Scientific Electronic Library Online), with the keywords: Epidemiology, diarrhea, Clostridium difficile and hypervirulent strain.