RESUMO
Salmonella Typhimurium is a pathogen of clinical relevance and a model of study in host-pathogen interactions. The virulence and stress-related periplasmic protein VisP is important during S. Typhimurium pathogenesis. It supports bacteria invading host cells, surviving inside macrophages, swimming, and succeeding in murine colitis model, O-antigen assembly, and responding to cationic antimicrobial peptides. This study aimed to investigate the role of the O-antigen molecular ruler WzzST and the periplasmic protein VisP in swarming motility and osmotic stress response. Lambda red mutagenesis was performed to generate single and double mutants, followed by swarming motility, qRT-PCR, Western blot, and growth curves. Here we demonstrate that the deletion of visP affects swarming under osmotic stress and changes the expression levels of genes responsible for chemotaxis, flagella assembly, and general stress response. The deletion of the gene encoding for the O-antigen co-polymerase wzzST increases swarming motility but not under osmotic stress. A second mutation in O-antigen co-polymerase wzzST in a ΔvisP background affected gene expression levels. The ΔvisP growth was affected by sodium and magnesium levels on N-minimum media. These data indicate that WzzST has a role in swarming the motility of S. Typhimurium, as the VisP is involved in chemotaxis and osmotic stress, specifically in response to MgCl2 and NaCl.
Assuntos
Antígenos O , Salmonella typhimurium , Animais , Proteínas de Bactérias/metabolismo , Quimiotaxia/genética , Flagelos/fisiologia , Camundongos , Antígenos O/genética , Antígenos O/metabolismo , OsmorregulaçãoRESUMO
Urinary tract infections (UTIs) are a major public health concern in both community and hospital settings worldwide. Uropathogenic Escherichia coli (UPEC) is the main causative agent of UTI and increasingly associated with antibiotic resistance. Herein, we report the draft genome sequence of 9 fluoroquinolone-resistant UPEC isolates from Brazil and examine selected major phenotypic features, such as antimicrobial resistance profile, phylogroup, serotype, sequence type (ST), virulence genes, and resistance marks. Besides the quinolone resistance, beta-lactams, ESBL production, aminoglycosides, and tetracycline resistance were observed. High prevalence of 20 virulence genes was detected in all isolates, such as those encoding type 1 fimbriae, acid tolerance system, and hemolysin E, particularly within E. coli B2 phylogroup, as ST131 and ST1193 strains, among other genomic analyses as genomic islands, resistance plasmids, and integron identification.
Assuntos
Infecções por Escherichia coli , Genoma Bacteriano , Infecções Urinárias , Escherichia coli Uropatogênica , Brasil , Farmacorresistência Bacteriana , Infecções por Escherichia coli/microbiologia , Fluoroquinolonas/farmacologia , Humanos , Infecções Urinárias/microbiologia , Escherichia coli Uropatogênica/efeitos dos fármacos , Escherichia coli Uropatogênica/genética , Fatores de Virulência/genéticaRESUMO
The aims of this work were to evaluate the antibacterial and antiproliferative potential in vitro of the metal complex with 4-aminobenzoic acid (Ag-pABA) and a drug delivery system based on bacterial cellulose (BC-Ag-pABA). The Ag-pABA complex was characterized by elemental analysis, high resolution mass spectrometry and single-crystal X-ray diffraction techniques, which indicated a 1:2 metal/pABA composition plus a nitrate ion coordinated to silver by the oxygen atom, with the coordination formula [Ag (C7H7NO2)2(NO3)]. The coordination of pABA to the silver ion occurred by the nitrogen atom. The in vitro antibacterial activity of the complex evaluated by minimum inhibitory concentration assays demonstrated the effective growth inhibitory activity against Gram-positive, Gram-negative biofilm producers and acid-alcohol resistant Bacillus. The antiproliferative activities against a panel of eight tumor cells demonstrated the activity of the complex with a significant selectivity index (SI). The DNA interaction capacity and the Ames Test indicated the absence of mutagenicity. The BC-Ag-pABA composite showed an effective capacity of sustained release of Ag-pABA. The observed results validate further studies on its mechanisms of action and the conditions that mediate the in vivo biological effects using animal models to confirm its safety and effectiveness for treatment of skin and soft tissues infected by bacterial pathogens, urinary tract infections and cancer.
Assuntos
Ácido 4-Aminobenzoico/química , Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Celulose/química , Prata/farmacologia , Antibacterianos/química , Preparações de Ação Retardada , Testes de Sensibilidade Microbiana , Prata/químicaRESUMO
Salmonella enterica serovars are associated with diarrhea and gastroenteritis and are a helpful model for understanding host-pathogen mechanisms. Salmonella enterica serovar Typhimurium regulates the distribution of O antigen (OAg) and presents a trimodal distribution based on Wzy polymerase and the WzzST (long-chain-length OAg [L-OAg]) and WzzfepE (very-long-chain-length OAg [VL-OAg]) copolymerases; however, several mechanisms regulating this process remain unclear. Here, we report that LPS modifications modulate the infectious process and that OAg chain length determination plays an essential role during infection. An increase in VL-OAg is dependent on Wzy polymerase, which is promoted by a growth condition resembling the environment of Salmonella-containing vacuoles (SCVs). The virulence- and stress-related periplasmic protein (VisP) participates in OAg synthesis, as a ΔvisP mutant presents a semirough OAg phenotype. The ΔvisP mutant has greatly decreased motility and J774 macrophage survival in a colitis model of infection. Interestingly, the phenotype is restored after mutation of the wzzST or wzzfepE gene in a ΔvisP background. Loss of both the visP and wzzST genes promotes an imbalance in flagellin secretion. L-OAg may function as a shield against host immune systems in the beginning of an infectious process, and VL-OAg protects bacteria during SCV maturation and facilitates intramacrophage replication. Taken together, these data highlight the roles of OAg length in generating phenotypes during S Typhimurium pathogenesis and show the periplasmic protein VisP as a novel protein in the OAg biosynthesis pathway.
Assuntos
Proteínas de Bactérias/metabolismo , Antígenos O/metabolismo , Infecções por Salmonella/microbiologia , Infecções por Salmonella/patologia , Salmonella typhimurium/metabolismo , Animais , Carga Bacteriana , Linhagem Celular , Colite/microbiologia , Colite/patologia , Modelos Animais de Doenças , Fezes/microbiologia , Feminino , Macrófagos/imunologia , Macrófagos/microbiologia , Camundongos Endogâmicos C57BL , Viabilidade Microbiana , FagocitoseRESUMO
Intestinal bacteria employ microbial metabolites from the microbiota and chemical signaling during cell-to-cell communication to regulate several cellular functions. Pathogenic bacteria are extremely efficient in orchestrating their response to these signals through complex signaling transduction systems. Precise coordination and interpretation of these multiple chemical cues is important within the gastrointestinal (GI) tract. Enteric foodborne pathogens, such as enterohemorrhagic Escherichia coli (EHEC) and Salmonella enterica serovar Typhimurium, or the surrogate murine infection model for EHEC, Citrobacter rodentium, are all examples of microorganisms that modulate the expression of their virulence repertoire in response to signals from the microbiota or the host, such as autoinducer-3 (AI-3), epinephrine (Epi), and norepinephrine (NE). The QseBC and QseEF two-component systems, shared by these pathogens, are involved in sensing these signals. We review how these signaling systems sense and relay these signals to drive bacterial gene expression; specifically, to modulate virulence. We also review how bacteria chat via chemical signals integrated with metabolite recognition and utilization to promote successful associations among enteric pathogens, the microbiota, and the host.
Assuntos
Citrobacter rodentium/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Microbioma Gastrointestinal , Interações Hospedeiro-Patógeno , Salmonella typhimurium/efeitos dos fármacos , Transdução de Sinais , Fatores de Virulência/biossíntese , Animais , CamundongosRESUMO
UNLABELLED: Enteric pathogens such as enterohemorrhagic Escherichia coli (EHEC) and Citrobacter rodentium, which is largely used as a surrogate EHEC model for murine infections, are exposed to several host neurotransmitters in the gut. An important chemical exchange within the gut involves the neurotransmitters epinephrine and/or norepinephrine, extensively reported to increase virulence gene expression in EHEC, acting through two bacterial adrenergic sensors: QseC and QseE. However, EHEC is unable to establish itself and cause its hallmark lesions, attaching and effacing (AE) lesions, on murine enterocytes. To address the role of these neurotransmitters during enteric infection, we employed C. rodentium Both EHEC and C. rodentium harbor the locus of enterocyte effacement (LEE) that is necessary for AE lesion formation. Here we show that expression of the LEE, as well as that of other virulence genes in C. rodentium, is also activated by epinephrine and/or norepinephrine. Both QseC and QseE are required for LEE gene activation in C. rodentium, and the qseC and qseE mutants are attenuated for murine infection. C. rodentium has a decreased ability to colonize dopamine ß-hydroxylase knockout (Dbh(-/-)) mice, which do not produce epinephrine and norepinephrine. Both adrenergic sensors are required for C. rodentium to sense these neurotransmitters and activate the LEE genes during infection. These data indicate that epinephrine and norepinephrine are sensed by bacterial adrenergic receptors during enteric infection to promote activation of their virulence repertoire. This is the first report of the role of these neurotransmitters during mammalian gastrointestinal (GI) infection by a noninvasive pathogen. IMPORTANCE: The epinephrine and norepinephrine neurotransmitters play important roles in gut physiology and motility. Of note, epinephrine and norepinephrine play a central role in stress responses in mammals, and stress has profound effects on GI function. Bacterial enteric pathogens exploit these neurotransmitters as signals to coordinate the regulation of their virulence genes. The bacterial QseC and QseE adrenergic sensors are at the center of this regulatory cascade. C. rodentium is a noninvasive murine pathogen with a colonization mechanism similar to that of EHEC, enabling the investigation of host signals in mice. The presence of these neurotransmitters in the gut is necessary for C. rodentium to fully activate its virulence program, in a QseC/QseE-dependent manner, to successfully colonize its murine host. Our study data provide the first example of epinephrine and norepinephrine signaling within the gut to stimulate infection by a bacterial pathogen in a natural animal infection.
Assuntos
Citrobacter rodentium/patogenicidade , Infecções por Enterobacteriaceae/microbiologia , Escherichia coli Êntero-Hemorrágica/patogenicidade , Trato Gastrointestinal/microbiologia , Regulação Bacteriana da Expressão Gênica , Fosfoproteínas/genética , Receptores Adrenérgicos/genética , Animais , Citrobacter rodentium/genética , Dopamina beta-Hidroxilase/genética , Enterócitos/microbiologia , Escherichia coli Êntero-Hemorrágica/genética , Epinefrina/genética , Epinefrina/metabolismo , Infecções por Escherichia coli , Proteínas de Escherichia coli/genética , Genes Bacterianos , Interações Hospedeiro-Patógeno , Camundongos , Camundongos Knockout , Norepinefrina/genética , Norepinefrina/metabolismo , Vasoconstritores , Virulência/genéticaRESUMO
PURPOSE: The treatment of urinary tract infections (UTI) with antibiotics is commonly used, but recurrence and antibiotic resistance have been growing and concerning clinicians. We studied whether the rapid onset of a protective biofilm may be responsible for the lack of effectiveness of antibiotics against selected bacteria. MATERIALS AND METHODS: Two established uropathogenic Escherichia coli strains, UTI89 and CFT073, and two Pseudomonas aeruginosa strains, PA01 and Boston-41501, were studied to establish a reliable biofilm formation process. Bacterial growth (BG) was determined by optical density at 600 nm (OD 600) using a spectrophotometer, while biofilm formation (BF) using crystal violet staining was measured at OD 550. Next, these bacterial strains were treated with clinically relevant antibiotics, ciprofloxacin HCl (200 ng/mL and 2 µg/mL), nitrofurantoin (20 µg/mL and 40 µg/mL) and ampicillin (50 µg/mL) at time points of 0 (T0) or after 6 hours of culture (T6). All measurements, including controls (bacteria -1% DMSO), were done in triplicates and repeated three times for consistency. RESULTS: The tested antibiotics effectively inhibited both BG and BF when administered at T0 for UPEC strains, but not when the antibiotic administration started 6 hours later. For Pseudomonas strains, only Ciprofloxacin was able to significantly inhibit bacterial growth at T0 but only at the higher concentration of 2 µg/mL for T6. CONCLUSION: When established UPEC and Pseudomonas bacteria were allowed to culture for 6 hours before initialization of treatment, the therapeutic effect of selected antibiotics was greatly suppressed when compared to immediate treatment, probably as a result of the protective nature of the biofilm.
Assuntos
Antibacterianos/administração & dosagem , Biofilmes/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Pseudomonas aeruginosa/efeitos dos fármacos , Ampicilina/administração & dosagem , Anti-Infecciosos Urinários , Biofilmes/crescimento & desenvolvimento , Ciprofloxacina/administração & dosagem , Farmacorresistência Bacteriana , Escherichia coli/fisiologia , Concentração de Íons de Hidrogênio , Testes de Sensibilidade Microbiana , Nitrofurantoína/administração & dosagem , Pseudomonas aeruginosa/fisiologia , Valores de Referência , Reprodutibilidade dos Testes , Fatores de Tempo , Infecções Urinárias/tratamento farmacológicoRESUMO
Purpose The treatment of urinary tract infections (UTI) with antibiotics is commonly used, but recurrence and antibiotic resistance have been growing and concerning clinicians. We studied whether the rapid onset of a protective biofilm may be responsible for the lack of effectiveness of antibiotics against selected bacteria. Materials and Methods Two established uropathogenic Escherichia coli strains, UTI89 and CFT073, and two Pseudomonas aeruginosa strains, PA01 and Boston-41501, were studied to establish a reliable biofilm formation process. Bacterial growth (BG) was determined by optical density at 600 nm (OD 600) using a spectrophotometer, while biofilm formation (BF) using crystal violet staining was measured at OD 550. Next, these bacterial strains were treated with clinically relevant antibiotics, ciprofloxacin HCl (200 ng/mL and 2 μg/mL), nitrofurantoin (20 μg/mL and 40 μg/mL) and ampicillin (50 μg/mL) at time points of 0 (T0) or after 6 hours of culture (T6). All measurements, including controls (bacteria -1% DMSO), were done in triplicates and repeated three times for consistency. Results The tested antibiotics effectively inhibited both BG and BF when administered at T0 for UPEC strains, but not when the antibiotic administration started 6 hours later. For Pseudomonas strains, only Ciprofloxacin was able to significantly inhibit bacterial growth at T0 but only at the higher concentration of 2 μg/mL for T6. Conclusion When established UPEC and Pseudomonas bacteria were allowed to culture for 6 hours before initialization of treatment, the therapeutic effect of selected antibiotics was greatly suppressed when compared to immediate treatment, probably as a result of the protective nature of the biofilm. .
Assuntos
Antibacterianos/administração & dosagem , Biofilmes/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Pseudomonas aeruginosa/efeitos dos fármacos , Anti-Infecciosos Urinários , Ampicilina/administração & dosagem , Biofilmes/crescimento & desenvolvimento , Ciprofloxacina/administração & dosagem , Farmacorresistência Bacteriana , Escherichia coli/fisiologia , Concentração de Íons de Hidrogênio , Testes de Sensibilidade Microbiana , Nitrofurantoína/administração & dosagem , Pseudomonas aeruginosa/fisiologia , Valores de Referência , Reprodutibilidade dos Testes , Fatores de Tempo , Infecções Urinárias/tratamento farmacológicoRESUMO
Proteus mirabilis is an important cause of urinary tract infection (UTI) in patients with complicated urinary tracts. Thirty-five strains of P. mirabilis isolated from UTI were examined for the adherence capacity to epithelial cells. All isolates displayed the aggregative adherence (AA) to HEp-2 cells, a phenotype similarly presented in LLC-MK(2) cells. Biofilm formation on polystyrene was also observed in all strains. The mannose-resistant Proteus-like fimbriae (MR/P), Type I fimbriae and AAF/I, II and III fimbriae of enteroaggregative Escherichia coli were searched by the presence of their respective adhesin-encoding genes. Only the MR/P fimbrial subunits encoding genes mrpA and mrpH were detected in all isolates, as well as MR/P expression. A mutation in mrpA demonstrated that MR/P is involved in aggregative adherence to HEp-2 cells, as well as in biofilm formation. However, these phenotypes are multifactorial, because the mrpA mutation reduced but did not abolish both phenotypes. The present results reinforce the importance of MR/P as a virulence factor in P. mirabilis due to its association with AA and biofilm formation, which is an important step for the establishment of UTI in catheterized patients.
Assuntos
Aderência Bacteriana/fisiologia , Células Epiteliais/microbiologia , Proteus mirabilis/fisiologia , Infecções Urinárias/microbiologia , Adesinas Bacterianas/genética , Adesinas de Escherichia coli/genética , Adolescente , Adulto , Idoso , Animais , Aderência Bacteriana/genética , Proteínas de Bactérias/genética , Biofilmes/crescimento & desenvolvimento , Linhagem Celular , Criança , Pré-Escolar , Feminino , Proteínas de Fímbrias/genética , Deleção de Genes , Humanos , Lactente , Macaca mulatta , Masculino , Pessoa de Meia-Idade , Poliestirenos , Proteus mirabilis/genética , Proteus mirabilis/isolamento & purificaçãoRESUMO
Enteroaggregative Escherichia coli (EAEC) is distinguished by its characteristic aggregative adherence (AA) pattern to cultured epithelial cells. In this study we investigated the role of type I fimbriae (TIF) in the AA pattern to HEp-2 cells and in biofilm formation. Accentuation of this pattern was observed when the adherence assay was performed in the absence of mannose. This effect was observed in the prototype EAEC strain 042 (O44:H18), O128:H35 strains and for other EAEC serotypes. Antiserum against TIF decreased AA by 70% and 90% for strains 042 and 18 (O128:H35 prototype strain), respectively. A non-polar knockout of fimD, the TIF usher, in strains 042 and 18 resulted in inhibition of the accentuated AA pattern of approximately 80% and 70% respectively, and biofilm formation diminution of 49% for 042::fimD and 76% for 18::fimD. Our data evidence a role for TIF in the AA pattern and in EAEC biofilm formation, demonstrating that these phenotypes are multifactorial.