RESUMEN
BACKGROUND: Carbapenem-resistant Acinetobacter baumannii (CRAB) frequently causes both healthcare-associated infections and nosocomial outbreaks in burn medicine/plastic surgery and beyond. Owing to the high antibiotic resistance, infections are difficult to treat, and patient outcomes are often compromised. The environmental persistence capability of CRAB favors its transmission in hospitals. A comprehensive analysis and understanding of CRAB epidemiology and microbiology are essential for guiding management. METHODS: A three-year retrospective cohort study (2020-2022) was conducted in a German tertiary burn and plastic surgery center. In addition to epidemiological analyses, microbiological and molecular techniques, including whole-genome sequencing, were applied for the comprehensive examination of isolates from CRAB-positive patients. RESULTS: During the study period, eight CRAB cases were found, corresponding to an overall incidence of 0.2 CRAB cases per 100 cases and an incidence density of 0.35 CRAB cases per 1000 patient-days. Six cases (75%) were treated in the burn intensive care unit, and four cases (50%) acquired CRAB in the hospital. Molecular analyses comprising 74 isolates supported the epidemiologic assumption that hospital acquisitions occurred within two separate clusters. In one of these clusters, environmental CRAB contamination of anesthesia equipment may have enabled transmission. Furthermore, molecular diversity of CRAB isolates within patients was observed. CONCLUSIONS: CRAB can pose a challenge in terms of infection prevention and control, especially if cases are clustered in time and space on a ward. Our study demonstrates that high-resolution phylogenetic analysis of several bacterial isolates from single patients can greatly aid in understanding transmission chains and helps to take precision control measures.
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Infecciones por Acinetobacter , Acinetobacter baumannii , Carbapenémicos , Infección Hospitalaria , Control de Infecciones , Acinetobacter baumannii/genética , Acinetobacter baumannii/efectos de los fármacos , Acinetobacter baumannii/aislamiento & purificación , Humanos , Infecciones por Acinetobacter/epidemiología , Infecciones por Acinetobacter/microbiología , Alemania/epidemiología , Carbapenémicos/farmacología , Estudios Retrospectivos , Masculino , Femenino , Persona de Mediana Edad , Infección Hospitalaria/epidemiología , Infección Hospitalaria/microbiología , Anciano , Adulto , Control de Infecciones/métodos , Epidemiología Molecular , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Quemaduras/microbiología , Quemaduras/complicaciones , Cirugía Plástica , Unidades de Quemados , Secuenciación Completa del Genoma , Incidencia , Pruebas de Sensibilidad MicrobianaRESUMEN
Acinetobacter species such as A. venetianus and A. guillouiae have been studied for various biotechnology applications, including bioremediation of recalcitrant and harmful environmental contaminants, as well as bioengineering of enzymes and diagnostic materials. Bacteria used in biotechnology are often combined with other microorganisms in mixtures to formulate efficacious commercial products. However, if the mixture contained a closely related Acinetobacter pathogen such as A. baumannii (Ab), it remains unclear whether the survival and virulence of Ab would be masked or augmented. This uncertainty poses a challenge in ensuring the safety of such biotechnology products, since Ab is one of the most significant pathogens for both hospital and community -acquired infections. This research aimed to investigate the growth and virulence of Ab within a mixture of 11 bacterial species formulated as a mock microbial mixture (MM). Growth challenges with environmental stressors (i.e., temperature, pH, sodium, iron, and antibiotics) revealed that Ab could thrive under diverse conditions except in the presence of ciprofloxacin. When cultured alone, Ab exhibited significantly more growth in the presence of almost all the environmental stressors than when it was co-incubated with the MM. During the exposure of A549 lung epithelial cells to the MM, Ab growth was stimulated compared to that in standard mammalian culture media. Cytotoxicity caused by Ab was suppressed in the presence of the MM. Lymphocytes were significantly reduced in mice exposed to Ab with or without MM via intravenous injection. The levels of the splenic cytokines IL-1α, IL-1ß, MCP-1, and MIP-1α were significantly reduced 24 h after exposure to Ab + MM. This study demonstrated that the presence of the MM marginally but significantly reduced the growth and virulence of Ab, which has implications for the safety of mixtures of microorganisms for biotechnological applications. Furthermore, these findings expand our understanding of the virulence of Ab during host-pathogen interactions.
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Infecciones por Acinetobacter , Acinetobacter baumannii , Animales , Acinetobacter baumannii/patogenicidad , Acinetobacter baumannii/crecimiento & desarrollo , Acinetobacter baumannii/efectos de los fármacos , Acinetobacter baumannii/genética , Virulencia , Ratones , Humanos , Infecciones por Acinetobacter/microbiología , Células A549 , Antibacterianos/farmacología , Femenino , Citocinas/metabolismo , Viabilidad Microbiana/efectos de los fármacosRESUMEN
BACKGROUND: Nosocomial infections are a global problem in hospitals all around the world. It is considered a major health problem, especially in developing countries. The increase in the patient's stay in hospitals has increased the mortality rate, and consequently, the costs drastically increase. The main purpose of using disinfectants in the hospital environment is to reduce the risk of nosocomial infections. Ethylene diamine tetra acetic acid (EDTA) causes lysis and increases susceptibility to antimicrobial agents in the planktonic form of bacteria. This substance affects the permeability of the outer membrane of bacteria. It also prevents the formation of biofilms by bacteria. MATERIALS AND METHODS: In the current study, 120 isolates of Acinetobacter baumannii (A. baumannii) were confirmed by phenotypic and genotypic methods. Antibiogram was performed and then the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of isolates against 5% sodium hypochlorite, ethanol %70, sayasept-HP 2%, chlorhexidine 2%, dettol 4/8% were evaluated. In addition, the disinfectant effect was re-evaluated with the mixture of EDTA solution. All isolates were examined for biofilm presence by crystal violet staining method in triplicates and repeated three times for each strain. Also for all isolates detection of efflux pump genes (Qac-E, qacE-Δ1, SUG-E) by PCR technique was done. RESULTS: Antibiogram results of A. baumannii showed that 6.7% were Multi-drug-resistant (MDR), and 89.2% were Extensively drug-resistant (XDR) isolates. The highest effect of disinfectants was related to 5% sodium hypochlorite, and the least effect was 70% ethanol. EDTA increases the efficacy of selected disinfectants significantly. The highest prevalence of the efflux pump genes was related to SUG-E (95%) and Qac-E (91.7%), and, the qacE-Δ1 gene with 12.5%. The biofilm production rate was 91.3% among all isolates. CONCLUSION: The best and safest way to disinfect hospital floors and surfaces is to choose the right disinfectants, and learn how to use them properly. In this study, a mixture of disinfectants and EDTA had a significant effect on bactericidal activity. it was found that improper use of disinfectants, especially the use of sub-inhibitory dilutions, increases the resistance of bacteria to disinfectants.
Asunto(s)
Acinetobacter baumannii , Biopelículas , Desinfectantes , Genotipo , Pruebas de Sensibilidad Microbiana , Fenotipo , Biopelículas/efectos de los fármacos , Biopelículas/crecimiento & desarrollo , Acinetobacter baumannii/efectos de los fármacos , Acinetobacter baumannii/genética , Acinetobacter baumannii/fisiología , Acinetobacter baumannii/aislamiento & purificación , Desinfectantes/farmacología , Humanos , Irán , Ácido Edético/farmacología , Farmacorresistencia Bacteriana/genética , Antibacterianos/farmacología , Infecciones por Acinetobacter/microbiología , Hipoclorito de Sodio/farmacología , Infección Hospitalaria/microbiología , Clorhexidina/farmacologíaRESUMEN
Introduction: Acinetobacter baumannii (AB) is rising as a human pathogen of critical priority worldwide as it is the leading cause of opportunistic infections in healthcare settings and carbapenem-resistant AB is listed as a "super bacterium" or "priority pathogen for drug resistance" by the World Health Organization. Methods: Clinical isolates of A. baumannii were collected and tested for antimicrobial susceptibility. Among them, carbapenem-resistant and carbapenem-sensitive A. baumannii were subjected to prokaryotic transcriptome sequencing. The change of sRNA and mRNA expression was analyzed by bioinformatics and validated by quantitative reverse transcription-PCR. Results: A total of 687 clinical isolates were collected, of which 336 strains of A. baumannii were resistant to carbapenem. Five hundred and six differentially expressed genes and nineteen differentially expressed sRNA candidates were discovered through transcriptomic profile analysis between carbapenem-resistant isolates and carbapenem-sensitive isolates. Possible binding sites were predicted through software for sRNA21 and adeK, sRNA27 and pgaC, sRNA29 and adeB, sRNA36 and katG, indicating a possible targeting relationship. A negative correlation was shown between sRNA21 and adeK (r = -0.581, P = 0.007), sRNA27 and pgaC (r = -0.612, P = 0.004), sRNA29 and adeB (r = -0.516, P = 0.020). Discussion: This study preliminarily screened differentially expressed mRNA and sRNA in carbapenem-resistant A. baumannii, and explored possible targeting relationships, which will help further reveal the resistance mechanism and provide a theoretical basis for the development of drugs targeting sRNA for the prevention and treatment of carbapenem-resistant A. baumannii infection.
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Infecciones por Acinetobacter , Acinetobacter baumannii , Antibacterianos , Carbapenémicos , Perfilación de la Expresión Génica , ARN Mensajero , Acinetobacter baumannii/genética , Acinetobacter baumannii/efectos de los fármacos , Carbapenémicos/farmacología , Humanos , Infecciones por Acinetobacter/microbiología , ARN Mensajero/genética , ARN Mensajero/metabolismo , Antibacterianos/farmacología , Regulación Bacteriana de la Expresión Génica , Pruebas de Sensibilidad Microbiana , Biología Computacional/métodos , ARN Bacteriano/genética , ARN Pequeño no Traducido/genética , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Transcriptoma , Genoma Bacteriano/genéticaRESUMEN
Acinetobacter baumannii is a pathogenic and multidrug-resistant Gram-negative bacterium that causes severe nosocomial infections. To better understand the mechanism of pathogenesis, we compare the proteomes of uninfected and infected human cells, revealing that transcription factor FOS is the host protein most strongly induced by A. baumannii infection. Pharmacological inhibition of FOS reduces the cytotoxicity of A. baumannii in cell-based models, and similar results are also observed in a mouse infection model. A. baumannii outer membrane vesicles (OMVs) are shown to activate the aryl hydrocarbon receptor (AHR) of host cells by inducing the host enzyme tryptophan-2,3-dioxygenase (TDO), producing the ligand kynurenine, which binds AHR. Following ligand binding, AHR is a direct transcriptional activator of the FOS gene. We propose that A. baumannii infection impacts the host tryptophan metabolism and promotes AHR- and FOS-mediated cytotoxicity of infected cells.
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Infecciones por Acinetobacter , Acinetobacter baumannii , Quinurenina , Receptores de Hidrocarburo de Aril , Receptores de Hidrocarburo de Aril/metabolismo , Receptores de Hidrocarburo de Aril/genética , Acinetobacter baumannii/metabolismo , Acinetobacter baumannii/genética , Acinetobacter baumannii/efectos de los fármacos , Humanos , Animales , Ratones , Infecciones por Acinetobacter/microbiología , Infecciones por Acinetobacter/metabolismo , Quinurenina/metabolismo , Proteínas Proto-Oncogénicas c-fos/metabolismo , Proteínas Proto-Oncogénicas c-fos/genética , Triptófano/metabolismo , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/genética , Interacciones Huésped-PatógenoRESUMEN
The quorum sensing (QS) system mediated by the abaI gene in Acinetobacter baumannii is crucial for various physiological and pathogenic processes. In this study, we constructed a stable markerless abaI knockout mutant (ΔabaI) strain using a pEXKm5-based allele replacement method to investigate the impact of abaI on A. baumannii. Proteomic analysis revealed significant alterations in protein expression between the wild type (WT) and ΔabaI mutant strains, particularly in proteins associated with membrane structure, antibiotic resistance, and virulence. Notably, the downregulation of key outer membrane proteins such as SurA, OmpA, OmpW, and BamA suggests potential vulnerabilities in outer membrane integrity, which correlate with structural abnormalities in the ΔabaI mutant strain, including irregular cell shapes and compromised membrane integrity, observed by scanning and transmission electron microscopy. Furthermore, diminished expression of regulatory proteins such as OmpR and GacA-GacS highlights the broader regulatory networks affected by abaI deletion. Functional assays revealed impaired biofilm formation and surface-associated motility in the mutant strain, indicative of altered colonization capabilities. Interestingly, the mutant showed a complex antibiotic susceptibility profile. While it demonstrated increased susceptibility to membrane-targeting antibiotics, its response to beta-lactams was more nuanced. Despite increased expression of metallo-beta-lactamase (MBL) superfamily proteins and DcaP-like protein, the mutant unexpectedly showed lower MICs for carbapenems (imipenem and meropenem) compared to the wild-type strain. This suggests that abaI deletion affects antibiotic susceptibility through multiple, potentially competing mechanisms. Further investigation is needed to fully elucidate the interplay between quorum sensing, antibiotic resistance genes, and overall antibiotic susceptibility in A. baumannii. Our findings underscore the multifaceted role of the abaI gene in modulating various cellular processes and highlight its significance in A. baumannii physiology, pathogenesis, and antibiotic resistance. Targeting the abaI QS system may offer novel therapeutic strategies for this clinically significant pathogen.
Asunto(s)
Acinetobacter baumannii , Antibacterianos , Proteínas Bacterianas , Biopelículas , Mutación , Percepción de Quorum , Acinetobacter baumannii/genética , Acinetobacter baumannii/efectos de los fármacos , Acinetobacter baumannii/patogenicidad , Biopelículas/efectos de los fármacos , Biopelículas/crecimiento & desarrollo , Virulencia/genética , Antibacterianos/farmacología , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Percepción de Quorum/genética , Percepción de Quorum/efectos de los fármacos , Regulación Bacteriana de la Expresión Génica/efectos de los fármacos , Pruebas de Sensibilidad Microbiana , Proteínas de la Membrana Bacteriana Externa/genética , Proteínas de la Membrana Bacteriana Externa/metabolismo , Infecciones por Acinetobacter/microbiología , Infecciones por Acinetobacter/tratamiento farmacológico , ProteómicaRESUMEN
Outer membrane vesicles (OMVs) are nanostructures derived from the outer membrane of Gram-negative bacteria. We previously demonstrated that vaccination with endotoxin-free OMVs isolated from an Acinetobacter baumannii strain lacking lipooligosaccharide (LOS) biosynthesis, due to a mutation in lpxD, provides full protection in a murine sepsis model. The present study characterizes the protein content of highly-purified OMVs isolated from LOS-replete and LOS-deficient strains. Four purification methods were evaluated to obtain highly purified OMV preparations: ultracentrifugation, size exclusion chromatography (SEC), ultracentrifugation followed by SEC, and Optiprep™. OMVs from each method were characterized using nanoparticle tracking analysis and electron microscopy. OMVs from LOS-deficient and LOS-replete strains purified using the Optiprep™ method were subjected to LC-MS/MS analysis to determine protein content. Significant differences in protein composition between OMVs from LOS-deficient and LOS-replete strains were found. Computational analyses using Bepipred 3.0 and SEMA 2.0 indicated that the lack of LOS led to the overexpression of immunogenic proteins found in LOS-containing OMVs and the presence of immune-stimulating proteins absent in LOS-replete OMVs. These findings have important implications for developing OMV-based vaccines against A. baumannii, using both LOS-containing and LOS-free OMVs preparations.
Asunto(s)
Acinetobacter baumannii , Proteínas de la Membrana Bacteriana Externa , Lipopolisacáridos , Acinetobacter baumannii/metabolismo , Acinetobacter baumannii/genética , Lipopolisacáridos/biosíntesis , Proteínas de la Membrana Bacteriana Externa/metabolismo , Proteínas de la Membrana Bacteriana Externa/genética , Infecciones por Acinetobacter/microbiología , Animales , Ratones , Espectrometría de Masas en Tándem , Membrana Externa Bacteriana/metabolismoRESUMEN
The use of monoclonal antibodies for the control of drug resistant nosocomial bacteria may alleviate a reliance on broad spectrum antimicrobials for treatment of infection. We identify monoclonal antibodies that may prevent infection caused by carbapenem resistant Acinetobacter baumannii. We use human immune repertoire mice (Kymouse platform mice) as a surrogate for human B cell interrogation to establish an unbiased strategy to probe the antibody-accessible target landscape of clinically relevant A. baumannii. After immunisation of the Kymouse platform mice with A. baumannii derived outer membrane vesicles (OMV) we identify 297 antibodies and analyse 26 of these for functional potential. These antibodies target lipooligosaccharide (OCL1), the Oxa-23 protein, and the KL49 capsular polysaccharide. We identify a single monoclonal antibody (mAb1416) recognising KL49 capsular polysaccharide to demonstrate prophylactic in vivo protection against a carbapenem resistant A. baumannii lineage associated with neonatal sepsis mortality in Asia. Our end-to-end approach identifies functional monoclonal antibodies with prophylactic potential against major lineages of drug resistant bacteria accounting for phylogenetic diversity and clinical relevance without existing knowledge of a specific target antigen. Such an approach might be scaled for a additional clinically important bacterial pathogens in the post-antimicrobial era.
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Infecciones por Acinetobacter , Acinetobacter baumannii , Anticuerpos Monoclonales , Ratones Transgénicos , Acinetobacter baumannii/inmunología , Acinetobacter baumannii/genética , Animales , Humanos , Anticuerpos Monoclonales/inmunología , Anticuerpos Monoclonales/farmacología , Infecciones por Acinetobacter/inmunología , Infecciones por Acinetobacter/prevención & control , Infecciones por Acinetobacter/microbiología , Ratones , Antibacterianos/farmacología , Anticuerpos Antibacterianos/inmunología , Femenino , Carbapenémicos/farmacología , Farmacorresistencia Bacteriana/inmunología , Farmacorresistencia Bacteriana/genética , Lipopolisacáridos/inmunologíaRESUMEN
In this work, the antibiotic resistance, biofilm formation capability, and clonal relatedness of 50 A. baumannii isolates collected from three hospitals in Ardabil city, Iran, were evaluated. Antibiotic sensitivity and biofilm formation of isolates were determined by disk diffusion and microtiter-plate methods, respectively. Molecular typing of isolates was also performed using repetitive sequence-based PCR (REP-PCR). The majority of isolates were resistant to cephems, aminoglycosides, and carbapenems, with 80 % classified as multi-drug resistant (MDR). While, only isolates collected from blood and tracheal were resistant to colistin. Additionally, 42 isolates (84 %) had biofilm formation capability. According to rep-PCR results, 34 isolates showed similar banding patterns, while 16 isolates had unique banding patterns. Finally, based on the molecular analysis, there was a direct relationship between biofilm formation and the antibiotic resistance of isolates. In other words, MDR isolates had a higher ability to form biofilm.
Asunto(s)
Infecciones por Acinetobacter , Acinetobacter baumannii , Antibacterianos , Biopelículas , Farmacorresistencia Bacteriana Múltiple , Pruebas de Sensibilidad Microbiana , Biopelículas/crecimiento & desarrollo , Biopelículas/efectos de los fármacos , Humanos , Antibacterianos/farmacología , Infecciones por Acinetobacter/microbiología , Irán , Farmacorresistencia Bacteriana Múltiple/genética , Acinetobacter baumannii/efectos de los fármacos , Acinetobacter baumannii/genética , Acinetobacter baumannii/aislamiento & purificación , Acinetobacter baumannii/fisiología , Tipificación Molecular , Reacción en Cadena de la Polimerasa , Colistina/farmacología , Adulto , Hospitales , Masculino , Femenino , Genotipo , Persona de Mediana EdadRESUMEN
BACKGROUND: This study was conducted to explore the effects of erythromycin on biofilms comprising Acinetobacter baumannii (A baumannii). METHODS: To clarify the effect of erythromycin on the biofilms of A baumannii, we collected pure Ab strains isolated and identified from a variety of sample types extracted from patients in the microbiological laboratory of our hospital from April to August 2023, and divided them into an experimental group (treated with erythromycin) and a control group (without erythromycin). The morphology and quantity of A baumannii biofilm were observed at 24h, 48h, 72h, and 5d post-treatment, respectively, and the expression of quorum sensing (QS) system gene (abaI, abaR) mRNA was detected by fluorescence quantitative PCR. RESULTS: The results showed that A baumanniis are prone to form multiple drug-resistant (MDR) bacteria, against which the most commonly used clinical antibiotics are ineffective. Overall, we found that the number of bacteria, the number of bacteria in the biofilm, and the number of biofilms formed gradually increased over time, with a statistical difference (Pâ <â .05). After the addition of erythromycin, significant improvements in biofilm formation were achieved, indicating that erythromycin can destroy A baumannii biofilms, inhibiting bacterial growth to a certain extent. The expression levels of abaI and abaR gradually increased over time, indicating that the role of the QS system became more apparent over time. Biofilm formation is related to the QS system of A baumanniis. After erythromycin treatment, abaI and abaR mRNA expression was downregulated in the experimental group. CONCLUSION: Erythromycin disrupts A baumannii biofilms by destroying the quorum sensing system.
Asunto(s)
Acinetobacter baumannii , Antibacterianos , Biopelículas , Eritromicina , Percepción de Quorum , Acinetobacter baumannii/efectos de los fármacos , Acinetobacter baumannii/genética , Biopelículas/efectos de los fármacos , Eritromicina/farmacología , Percepción de Quorum/efectos de los fármacos , Antibacterianos/farmacología , Humanos , Infecciones por Acinetobacter/microbiología , Infecciones por Acinetobacter/tratamiento farmacológico , Pruebas de Sensibilidad Microbiana , Farmacorresistencia Bacteriana Múltiple/genéticaRESUMEN
Background: Type VI secretion system (T6SS) is widely present in Gram-negative bacteria and directly mediates antagonistic prokaryote interactions. PAAR (proline-alanine-alanine-arginine repeats) proteins have been proven essential for T6SS-mediated secretion and target cell killing. Although PAAR proteins are commonly found in A. baumannii, their biological functions are not fully disclosed yet. In this study, we investigated the functions of a PAAR protein termed TagP (T6SS-associated-gene PAAR), encoded by the gene ACX60_RS09070 outside the core T6SS locus of A. baumannii strain ATCC 17978. Methods: In this study, tagP null and complement A. baumannii ATCC 17978 strains were constructed. The influence of TagP on T6SS function was investigated through Hcp detection and bacterial competition assay; the influence on environmental fitness was studied through in vitro growth, biofilm formation assay, surface motility assay, survivability in various simulated environmental conditions; the influence on pathogenicity was explored through cell adhesion and invasion assays, intramacrophage survival assay, serum survival assay, and G. melonella Killing assays. Quantitative transcriptomic and proteomic analyses were utilized to observe the global impact of TagP on bacterial status. Results: Compared with the wildtype strain, the tagP null mutant was impaired in several tested phenotypes such as surface motility, biofilm formation, tolerance to adverse environments, adherence to eukaryotic cells, endurance to serum complement killing, and virulence to Galleria melonella. Notably, although RNA-Seq and proteomics analysis revealed that many genes were significantly down-regulated in the tagP null mutant compared to the wildtype strain, there is no significant difference in their antagonistic abilities. We also found that Histone-like nucleoid structuring protein (H-NS) was significantly upregulated in the tagP null mutant at both mRNA and protein levels. Conclusions: This study enriches our understanding of the biofunction of PAAR proteins in A. baumannii. The results indicates that TagP involved in a unique modulation of fitness and virulence control in A. baumannii, it is more than a classic PAAR protein involved in T6SS, while how TagP play roles in the fitness and virulence of A. baumannii needs further investigation to clarify.
Asunto(s)
Acinetobacter baumannii , Proteínas Bacterianas , Biopelículas , Sistemas de Secreción Tipo VI , Acinetobacter baumannii/genética , Acinetobacter baumannii/patogenicidad , Acinetobacter baumannii/metabolismo , Virulencia/genética , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Sistemas de Secreción Tipo VI/genética , Sistemas de Secreción Tipo VI/metabolismo , Biopelículas/crecimiento & desarrollo , Animales , Regulación Bacteriana de la Expresión Génica , Factores de Virulencia/genética , Factores de Virulencia/metabolismo , Proteómica , Perfilación de la Expresión Génica , Adhesión Bacteriana/genética , Ratones , Infecciones por Acinetobacter/microbiología , Aptitud Genética , Macrófagos/microbiología , ProteomaRESUMEN
The histone-like nucleoid structuring (H-NS) protein is a DNA binding factor, found in gammaproteobacteria, with functional equivalents in diverse microbes. Universally, such proteins are understood to silence transcription of horizontally acquired genes. Here, we identify transposon capture as a major overlooked function of H-NS. Using genome-scale approaches, we show that H-NS bound regions are transposition "hotspots". Since H-NS often interacts with pathogenicity islands, such targeting creates clinically relevant phenotypic diversity. For example, in Acinetobacter baumannii, we identify altered motility, biofilm formation, and interactions with the human immune system. Transposon capture is mediated by the DNA bridging activity of H-NS and, if absent, more ubiquitous transposition results. Consequently, transcribed and essential genes are disrupted. Hence, H-NS directs transposition to favour evolutionary outcomes useful for the host cell.
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Acinetobacter baumannii , Proteínas Bacterianas , Elementos Transponibles de ADN , Proteínas de Unión al ADN , Elementos Transponibles de ADN/genética , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/genética , Proteínas de Unión al ADN/metabolismo , Proteínas de Unión al ADN/genética , Acinetobacter baumannii/genética , Acinetobacter baumannii/metabolismo , Humanos , Biopelículas/crecimiento & desarrollo , Regulación Bacteriana de la Expresión Génica , ADN Bacteriano/genética , ADN Bacteriano/metabolismo , Genoma Bacteriano , Islas GenómicasRESUMEN
The rising frequency of multidrug-resistant (MDR) Acinetobacter baumannii infections represents a significant public health challenge in Bangladesh. Genomic analysis of bacterial pathogens enhances surveillance and control efforts by providing insights into genetic diversity, antimicrobial resistance (AMR) profiles, and transmission dynamics. In this study, we conducted a comprehensive bioinformatic analysis of 82 whole-genome sequences (WGS) of A. baumannii from Bangladesh to understand their genomic epidemiological characteristics. WGS of the MDR and biofilm-forming A. baumannii strain S1C revealed the presence of 28 AMR genes, predicting its pathogenicity and classification within sequence type ST2. Multi-locus sequence typing (MLST) genotyping suggested heterogeneity in the distribution of clinical A. baumannii strains in Bangladesh, with a predominance of ST575. The resistome diversity was evident from the detection of 82 different AMR genes, with antibiotic inactivation being the most prevalent resistance mechanism. All strains were predicted to be multidrug-resistant. The observed virulence genes were associated with immune evasion, biofilm formation, adherence, nutrient acquisition, effector delivery, and other mechanisms. Mobile genetic elements carrying AMR genes were predicted in 68.29% (N = 56) of the genomes. The "open" state of the pan-genome and a high proportion of accessory genes highlighted the genome plasticity and diversity of A. baumannii in Bangladesh. Additionally, phylogenomic analysis indicated clustering of A. baumannii strains into three separate clades according to sequence type. In summary, our findings offer detailed insights into the genomic landscape of A. baumannii in Bangladesh, contributing to our understanding of its epidemiology and pathogenicity and informing strategies to combat this pathogen.
Asunto(s)
Infecciones por Acinetobacter , Acinetobacter baumannii , Farmacorresistencia Bacteriana Múltiple , Genoma Bacteriano , Filogenia , Acinetobacter baumannii/genética , Acinetobacter baumannii/efectos de los fármacos , Acinetobacter baumannii/clasificación , Bangladesh/epidemiología , Farmacorresistencia Bacteriana Múltiple/genética , Infecciones por Acinetobacter/epidemiología , Infecciones por Acinetobacter/microbiología , Humanos , Antibacterianos/farmacología , Secuenciación Completa del Genoma , Tipificación de Secuencias Multilocus , Genómica/métodos , Masculino , Adulto , Femenino , Epidemiología Molecular , Persona de Mediana Edad , Biopelículas , Adolescente , Adulto Joven , Niño , Pruebas de Sensibilidad MicrobianaRESUMEN
TLRs initiate innate immune signaling pathways via Toll/IL-1R (TIR) domains on their cytoplasmic tails. Various bacterial species also express TIR domain-containing proteins that contribute to bacterial evasion of the innate immune system. Bacterial TIR domains, along with the mammalian sterile α and TIR motif-containing protein 1 and TIRs from plants, also have been found to exhibit NADase activity. Initial X-ray crystallographic studies of the bacterial TIR from Acinetobacter baumannii provided insight into bacterial TIR structure but were unsuccessful in cocrystallization with the NAD+ ligand, leading to further questions about the TIR NAD binding site. In this study, we designed a Course-Based Undergraduate Research Experience (CURE) involving 16-20 students per year to identify amino acids crucial for NADase activity of A. baumannii TIR domain protein and the TIR from Escherichia coli (TIR domain-containing protein C). Students used structural data to identify amino acids that they hypothesized would play a role in TIR NADase activity, and created plasmids to express mutated TIRs through site-directed mutagenesis. Mutant TIRs were expressed, purified, and tested for NADase activity. The results from these studies provide evidence for a conformational change upon NAD binding, as was predicted by recent cryogenic electron microscopy and hydrogen-deuterium exchange mass spectrometry studies. Along with corroborating recent characterization of TIR NADases that could contribute to drug development for diseases associated with dysregulated TIR activity, this work also highlights the value of CURE-based projects for inclusion of a diverse group of students in authentic research experiences.
Asunto(s)
Acinetobacter baumannii , NAD+ Nucleosidasa , Acinetobacter baumannii/genética , NAD+ Nucleosidasa/metabolismo , NAD+ Nucleosidasa/genética , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/química , Humanos , NAD/metabolismo , Sitios de Unión , Dominios Proteicos , Mutagénesis Sitio-Dirigida , Cristalografía por Rayos X , Inmunidad InnataRESUMEN
The discovery of Replication Competent Circular DNA molecules in mammalian cells and tissues is being linked to debilitating diseases, such as multiple sclerosis (MS), bovine spongiform encephalopathy (BSE), and colorectal cancer (CRC). These circular DNA molecules, otherwise known as bovine meat and milk factors (BMMFs) and Slow Progressive Hidden INfections of variable (X) latency (SPHINX), bear significant (80%) sequence similarity with the plasmids of Acinetobacter baumannii strains. Nanostructures, such as bacterial outer membrane vesicles (OMVs) serve as vehicles for transporting biomolecular cargo and have the potential to facilitate interkingdom lateral mobility of DNA. Strengthening the proposed hypothesis, this study demonstrates that OMVs derived from A. baumannii DS002 carrying four plasmids and genome (pTS236) of phage, AbDs1, successfully reached different parts of the body, including the central nervous system, following the injection of fluorescein isothiocyanate (FITC)-labeled OMVs into experimental mice. Out of the four OMV-associated plasmids, three (pTS4586, pTS9900, and pTS134338) were identified within the lumen, and the fourth one (pTS11291) was found on the surface of OMVs. In addition to the indigenous plasmids, the phage-encoded protein, Orf96, anchored on the surface of the OMVs by establishing a strong interaction with the OMV-associated porin, OmpA. Intriguingly, a subset of labeled OMVs, when incubated with Neuro2A cells, translocated across the membrane and reached to the cytoplasmic space of the cells. Collectively, the experimental evidence presented herein underscores the promising potential of OMVs as vehicles for delivering molecular cargo containing plasmids and phage genomes to diverse mammalian tissues and cells. IMPORTANCE: Several independent studies have demonstrated the existence of replication competent circular DNA molecules of bacterial and viral origin in mammalian cells and tissues. However, studies about their origin and lateral mobility to mammalian cells are scarce. Our work describes the existence of circular DNA, similar to that of DNA molecules identified in mammalian cells, OMVs derived from soil isolate of A. baumannii DS002. Furthermore, the work also provides visual evidence that demonstrates the passage of labeled OMVs to different organs of experimental mice within hours after intravenously administering OMVs into experimental mice. Some of the labeled OMVs have even crossed the membrane of Neuro2A, suggesting the existence of interkingdom horizontal mobility between bacteria and mammals.
Asunto(s)
Acinetobacter baumannii , ADN Circular , Transferencia de Gen Horizontal , Plásmidos , Animales , Ratones , Plásmidos/genética , Acinetobacter baumannii/genética , Acinetobacter baumannii/metabolismo , Bovinos , ADN Circular/genética , ADN Circular/metabolismo , Membrana Externa Bacteriana/metabolismo , Femenino , Bacteriófagos/genética , Bacteriófagos/fisiología , Carne/microbiología , Leche/microbiología , Infecciones por Acinetobacter/microbiología , Vesículas Extracelulares/metabolismo , Ratones Endogámicos BALB C , ADN Bacteriano/genéticaRESUMEN
Carbapenem-resistant Acinetobacter baumannii (CRAB) is a major human pathogen and a research priority for developing new antimicrobial agents. CRAB is a causative agent of a variety of infections in different body sites. One of the manifestations is catheter-associated urinary tract infection, which exposes the bacteria to the host's urine, creating a particular environment. Exposure of two CRAB clinical isolates, AB5075 and AMA40, to human urine (HU) resulted in the differential expression levels of 264 and 455 genes, respectively, of which 112 were common to both strains. Genes within this group play roles in metabolic pathways such as phenylacetic acid (PAA) catabolism, the Hut system, the tricarboxylic acid (TCA) cycle, and other processes like quorum sensing and biofilm formation. These results indicate that the presence of HU induces numerous adaptive changes in gene expression of the infecting bacteria. These changes presumably help bacteria establish and thrive in the hostile conditions in the urinary tract. These analyses advance our understanding of CRAB's metabolic adaptations to human fluids, as well as expand knowledge on bacterial responses to distinct human fluids containing different concentrations of human serum albumin (HSA).
Asunto(s)
Acinetobacter baumannii , Carbapenémicos , Orina , Acinetobacter baumannii/genética , Acinetobacter baumannii/efectos de los fármacos , Acinetobacter baumannii/metabolismo , Humanos , Carbapenémicos/farmacología , Orina/microbiología , Regulación Bacteriana de la Expresión Génica/efectos de los fármacos , Antibacterianos/farmacología , Infecciones por Acinetobacter/microbiología , Infecciones por Acinetobacter/orina , Adaptación Fisiológica/genética , Infecciones Urinarias/microbiología , Biopelículas/crecimiento & desarrollo , Biopelículas/efectos de los fármacos , Farmacorresistencia Bacteriana/genéticaRESUMEN
Acinetobacter baumannii poses a significant health threat because of its frequent implications in hospital outbreaks and multidrug resistance (MDR). Here, we studied four A. baumannii isolates recovered during a hospital outbreak of severe or fatal cases to elucidate their diversity and factors contributing to their increased virulence and antibiotic resistance. The isolates were identified using MALDI-ToF and characterized using comparative genomics, PCR, and antimicrobial susceptibility tests. They were classified as ST126 and exhibited fewer than five chromosomal single-nucleotide variants and the same extrachromosomal content, indicating that they are a single strain (A. baumannii AB01). A. baumannii AB01 showed an MDR phenotype that could be linked to the carriage of parC and gyrA mutations, efflux transporters, aminoglycoside resistance genes, a class C beta-lactamase, and three carbapenemases, some of which are encoded on a 72 kb plasmid. ST126 is infrequent and has not been reported in Latin America, and our genomic data indicate a plausible origin for A. baumannii AB01 within the Pan Pacific region.
Asunto(s)
Infecciones por Acinetobacter , Acinetobacter baumannii , Proteínas Bacterianas , Brotes de Enfermedades , Farmacorresistencia Bacteriana Múltiple , Pruebas de Sensibilidad Microbiana , Plásmidos , beta-Lactamasas , beta-Lactamasas/genética , Humanos , Infecciones por Acinetobacter/microbiología , Infecciones por Acinetobacter/epidemiología , Acinetobacter baumannii/genética , Acinetobacter baumannii/efectos de los fármacos , Acinetobacter baumannii/enzimología , Acinetobacter baumannii/aislamiento & purificación , Farmacorresistencia Bacteriana Múltiple/genética , Plásmidos/genética , Proteínas Bacterianas/genética , Antibacterianos/farmacología , Masculino , Femenino , Infección Hospitalaria/microbiología , Infección Hospitalaria/epidemiología , Persona de Mediana EdadRESUMEN
The emergence and spread of Acinetobacter baumannii pose a severe threat to public health, highlighting the urgent need for the next generation of therapeutics due to its increasing resistance to existing antibiotics. BfmR, a response regulator modulating virulence and antimicrobial resistance, shows a promising potential as a novel antimicrobial target. Developing BfmR inhibitors may propel a new therapeutic direction for intractable infection of resistant strains. In this study, we conducted a structure-based hierarchical virtual screening pipeline combining molecular docking, molecular dynamic simulation, and MM/GBSA calculation to sift the Specs chemical library and finally discover three novel potential BfmR inhibitors. The three hits can reduce the MIC of meropenem for the carbapenem-resistant Acinetobacter baumannii (CRAB) strain ZJ06. Similar to the BfmR knockout strain, Cmp-98 was demonstrated to downregulate the expression of K locus genes, indicating it as a BfmR inhibitor. Bacteria underwent harmful morphological changes after treatment with these inhibitors. Molecular dynamic simulations found that all the hits tend to dynamically bind to different positions of the phosphorylation site of BfmR. Wherein we identified a potential inhibitory-binding cleft, beside a possible activated binding cleft at the edge of the phosphorylation site. Restraining the ligand binding poses may help exert inhibitory effects. This study reports a group of new scaffold BfmR inhibitors, offering new insights for novel antibiotic therapeutics against CRAB.
Asunto(s)
Acinetobacter baumannii , Antibacterianos , Proteínas Bacterianas , Carbapenémicos , Pruebas de Sensibilidad Microbiana , Simulación del Acoplamiento Molecular , Simulación de Dinámica Molecular , Acinetobacter baumannii/efectos de los fármacos , Acinetobacter baumannii/genética , Carbapenémicos/farmacología , Antibacterianos/farmacología , Antibacterianos/química , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/antagonistas & inhibidores , Humanos , Infecciones por Acinetobacter/microbiología , Infecciones por Acinetobacter/tratamiento farmacológico , Evaluación Preclínica de MedicamentosRESUMEN
Carbapenem-resistant Acinetobacter baumannii (CRAB) poses a significant threat to hospitalized patients as effective therapeutic options are scarce. Based on the genomic characteristics of the CRAB strain AB2877 harboring chromosome-borne blaOXA-23, which was isolated from the bronchoalveolar lavage fluid (BALF) of a patient in a respiratory intensive care unit (RICU), we systematically analyzed antibiotic resistance genes (ARGs) and the genetic context associated with ARGs carried by CRAB strains harboring chromosome-borne blaOXA-23 worldwide. Besides blaOXA-23, other ARGs were detected on the chromosome of the CRAB strain AB2877 belonging to ST208/1806 (Oxford MLST scheme). Several key genetic contexts associated with the ARGs were identified on the chromosome of the CRAB strain AB2877, including (1) the MDR region associated with blaOXA-23, tet(B)-tetR(B), aph(3'')-Ib, and aph(6)-Id (2); the resistance island AbGRI3 harboring armA and mph(E)-msr(E) (3); the Tn3-like composite transposon containing blaTEM-1D and aph(3')-Ia; and (4) the structure "ISAba1-blaADC-25." The first two genetic contexts were most common in ST195/1816, followed by ST208/1806. The last two genetic contexts were found most frequently in ST208/1806, followed by ST195/1816.IMPORTANCEThe blaOXA-23 gene can be carried by plasmid or chromosome, facilitating horizontal genetic transfer and increasing carbapenem resistance in healthcare settings. In this study, we focused on the genomic characteristics of CRAB strains harboring the chromosome-borne blaOXA-23 gene, and the important genetic contexts associated with blaOXA-23 and other ARGs were identified, and their prevalent clones worldwide were determined. Notably, although the predominant clonal CRAB lineages worldwide containing the MDR region associated with blaOXA-23, tet(B)-tetR(B), aph(3'')-Ib, and aph (6)-Id was ST195/1816, followed by ST208/1806, the CRAB strain AB2877 in our study belonged to ST208/1806. Our findings contribute to the knowledge regarding the dissemination of CRAB strains and the control of nosocomial infection.
Asunto(s)
Acinetobacter baumannii , Antibacterianos , Carbapenémicos , Farmacorresistencia Bacteriana Múltiple , beta-Lactamasas , Humanos , Acinetobacter baumannii/genética , Acinetobacter baumannii/efectos de los fármacos , Infecciones por Acinetobacter/microbiología , Infecciones por Acinetobacter/tratamiento farmacológico , Antibacterianos/farmacología , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , beta-Lactamasas/genética , Carbapenémicos/farmacología , Cromosomas Bacterianos/genética , Farmacorresistencia Bacteriana Múltiple/genética , Genoma Bacteriano , Pruebas de Sensibilidad Microbiana , Tipificación de Secuencias Multilocus , Secuenciación Completa del GenomaRESUMEN
OBJECTIVES: The emergence of multidrug-resistant (MDR) Acinetobacter baumannii has become a serious worldwide medical problem. This study was designed to clarify the genetic and epidemiological properties of MDR A. baumannii clinical isolates. METHODS: A total of 66 MDR A. baumannii isolates were obtained from 66 inpatients between May 2019 and February 2020 in a university hospital in Nepal. Whole genomes of these isolates were sequenced using next-generation sequencing. Phylogenetic trees were constructed from single nucleotide polymorphism concatemers. Multilocus sequence typing (MLST) and clonal complex (CC) analysis were conducted, and drug-resistance genes were identified. RESULTS: Of the 66 isolates, 26 harboured a gene encoding NDM-type metallo-ß-lactamase, and 55 harboured a gene encoding the 16S rRNA methyltransferase, ArmA. All isolates had point mutations in the quinolone-resistance-determining regions of gyrA and parC. Phylogenetic analysis showed that 55 isolates harboured armA, 26 harboured blaNDM-1, and14 harboured blaPER-7. Multilocus sequence typing and CC analysis revealed that 34 isolates belonged to CC2 (ST2), 10 to CC1 (nine ST1 and one ST623), and eight to CC149 (ST149). Compared to our previous study on MDR A. baumannii in Nepal in 2012, the isolation rate of CC2 increased, whereas that of CC149 decreased between 2012 and 2020. CONCLUSIONS: This study indicates that MDR A. baumannii producing carbapenemase and 16S rRNA methyltransferase, with high resistance to carbapenems and/or aminoglycosides, are spreading in medical settings in Nepal. The genetic backgrounds of MDR A. baumannii isolates have shifted to international clone 2 over several years.