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Antibiotics (Basel, Switzerland) Jan 2024Gram-negative bacteria are intrinsically more resistant to many frontline antibiotics, which is attributed to the permeability barrier of the outer membrane, drug efflux...
Gram-negative bacteria are intrinsically more resistant to many frontline antibiotics, which is attributed to the permeability barrier of the outer membrane, drug efflux pumps and porins. Consequently, discovery of new small molecules antibiotics to kill drug-resistant Gram-negative bacteria presents a significant challenge. Thanatin, a 21-residue insect-derived antimicrobial peptide, is known for its potent activity against Enterobacter Gram-negative bacteria, including drug-resistant strains. Here, we investigated a 15-residue N-terminal truncated analog PM15 (PIIYCNRRTGKCQRM) of thanatin to determine modes of action and antibacterial activity. PM15 and the P to Y and A substituted variants PM15Y and PM15A delineated interactions and permeabilization of the LPS-outer membrane. In antibacterial assays, PM15 and the analogs showed growth inhibition of strains of Gram-negative bacteria that is largely dependent on the composition of the culture media. Atomic-resolution structures of PM15 and PM15Y in free solution and in complex with LPS micelle exhibited persistent β-hairpin structures similar to native thanatin. However, in complex with LPS, the structures of peptides are more compact, with extensive packing interactions among residues across the two anti-parallel strands of the β-hairpin. The docked complex of PM15/LPS revealed a parallel orientation of the peptide that may be sustained by potential ionic and van der Waals interactions with the lipid A moiety of LPS. Further, PM15 and PM15Y bind to LptA, a monomeric functional variant of LptA, the periplasmic component of the seven-protein (A-G) complex involved in LPS transport. Taken together, the structures, target interactions and antibacterial effect of PM15 presented in the current study could be useful in designing thanatin-based peptide analogs.
PubMed: 38247633
DOI: 10.3390/antibiotics13010074 -
Journal of Global Antimicrobial... Mar 2024Wild birds are vectors of antimicrobial resistance. Birds living in close contact with humans or other animals, like feral pigeons (Columba livia), might be especially...
OBJECTIVES
Wild birds are vectors of antimicrobial resistance. Birds living in close contact with humans or other animals, like feral pigeons (Columba livia), might be especially prone to acquire resistance genes such as those encoding extended-spectrum beta-lactamases (ESBLs) and carbapenemases.
METHODS
Cloacal samples (n = 206) of free-living feral pigeons (C. livia) were collected in Sousse and Monastir, Tunisia. Antimicrobial susceptibility profiles were determined by disc-diffusion, and resistant isolates were short- and long-read whole-genome sequenced. Sequence analysis was performed using tools of the Centre for Genomic Epidemiology, and Phylogenetic analysis was performed based on the core-genome MLST.
RESULTS
Fourteen (14/206, 6.8%) pigeons harboured Enterobacterales resistant to last-generations cephalosporins, of which 10 were CTX-M-15- or CTX-M-27-producers, while two (1.0%) carried a VIM-2-producing Pseudomonas putida. Positive pigeons lived on four different livestock farms. Three STs (ST206, ST5584, ST8149) were identified among E. coli, of which ST5584 and ST8149 were found in two different farms. Genetic diversity was also observed in Enterobacter cloacae and P. putida isolates. The bla genes were chromosomally encoded, while the bla genes were carried on highly similar IncF/F-:A-:B53 plasmids. The bla gene was located on a class 1 integron co-harbouring several resistance genes.
CONCLUSION
Pigeons living on livestock farms carried clinically important resistance genes encoding ESBLs and carbapenemases. Our results evidenced that both clonal (ST8149 and ST5584) and plasmidic (IncF/F-:A-:B53) transfers played a role in the spread of resistance genes among pigeons. Further studies are needed to identify factors favouring the transfer and persistence of resistance genes within the pigeon communities.
Topics: Animals; Humans; Columbidae; Escherichia coli; Pseudomonas putida; Multilocus Sequence Typing; Tunisia; Phylogeny; beta-Lactamases; Anti-Infective Agents
PubMed: 38145799
DOI: 10.1016/j.jgar.2023.12.013 -
Antimicrobial Agents and Chemotherapy Dec 2023Carbapenems are considered last-resort antibiotics for the treatment of infections caused by multidrug-resistant , but carbapenem resistance due to acquisition of...
Carbapenems are considered last-resort antibiotics for the treatment of infections caused by multidrug-resistant , but carbapenem resistance due to acquisition of carbapenemase genes is a growing threat that has been reported worldwide. carbapenemase () is the most common type of carbapenemase in Canada and elsewhere; it can hydrolyze penicillins, cephalosporins, aztreonam, and carbapenems and is frequently found on mobile plasmids in the Tn transposon. This means that alongside clonal expansion, can disseminate through plasmid- and transposon-mediated horizontal gene transfer. We applied whole genome sequencing to characterize the molecular epidemiology of 829 carbapenemase-producing isolates collected by the Canadian Nosocomial Infection Surveillance Program from 2010 to 2021. Using a combination of short-read and long-read sequencing, we obtained 202 complete and circular -encoding plasmids. Using MOB-suite, 10 major plasmid clusters were identified from this data set which represented 87% (175/202) of the Canadian -encoding plasmids. We further estimated the genomic location of incomplete -encoding contigs and predicted a plasmid cluster for 95% (603/635) of these. We identified different patterns of carbapenemase mobilization across Canada related to different plasmid clusters, including clonal transmission of IncF-type plasmids (108/829, 13%) in clonal complex 258 and novel repE(pEh60-7) plasmids (44/829, 5%) in ST316, and horizontal transmission of IncL/M (142/829, 17%) and IncN-type plasmids (149/829, 18%) across multiple genera. Our findings highlight the diversity of genomic loci and indicate that multiple, distinct plasmid clusters have contributed to spread and persistence in Canada.
Topics: Humans; Canada; beta-Lactamases; Plasmids; Bacterial Proteins; Klebsiella pneumoniae; Anti-Bacterial Agents; Carbapenems; Genomics; Klebsiella Infections; Microbial Sensitivity Tests
PubMed: 37971242
DOI: 10.1128/aac.00860-23 -
Journal of Infection and Public Health Dec 2023We investigated 51 g-negative carbapenem-resistant Enterobacterales (CRE) isolates collected from 22 patients over a five-year period from six health care institutions...
BACKGROUND
We investigated 51 g-negative carbapenem-resistant Enterobacterales (CRE) isolates collected from 22 patients over a five-year period from six health care institutions in the Ochsner Health network in southeast Louisiana.
METHODS
Short genomic reads were generated using Illumina sequencing and assembled for each isolate. Isolates were classified as Enterobacter spp. (n = 20), Klebsiella spp. (n = 30), and Escherichia coli (n = 1) and grouped into 19 different multi-locus sequence types (MLST). Species and patient-specific core genomes were constructed representing ∼50% of the chromosomal genome.
RESULTS
We identified two sets of patients with genetically related infections; in both cases, the related isolates were collected > 6 months apart, and in one case, the isolates were collected in different locations. On the other hand, we identified four sets of patients with isolates of the same species collected within 21 days from the same location; however, none had genetically related infections. Genes associated with resistance to carbapenem drugs (blaKPC and/or blaCTX-M-15) were found in 76% of the isolates. We found three blaKPC variants (blaKPC-2, blaKPC-3, and blaKPC-4) associated with four different Enterobacter MLST variants, and two blaKPC variants (blaKPC-2, blaKPC-3) associated with seven different Klebsiella MLST variants.
CONCLUSIONS
Molecular surveillance is increasingly becoming a powerful tool to understand bacterial spread in both community and clinical settings. This study provides evidence that genetically related infections in clinical settings do not necessarily reflect temporal associations, and vice versa. Our results also highlight the regional genomic and resistance diversity within related bacterial lineages.
Topics: Humans; Carbapenems; Anti-Bacterial Agents; Multilocus Sequence Typing; Plasmids; Klebsiella pneumoniae; beta-Lactamases; Escherichia coli; Microbial Sensitivity Tests; Klebsiella Infections
PubMed: 37866269
DOI: 10.1016/j.jiph.2023.10.013 -
Surgery Open Science Dec 2023Ventilator-associated pneumonias (VAPs) are a complication of mechanical ventilation in the intensive care unit (ICU) that increase length of stay, morbidity, and...
INTRODUCTION
Ventilator-associated pneumonias (VAPs) are a complication of mechanical ventilation in the intensive care unit (ICU) that increase length of stay, morbidity, and mortality. While identifying and treating infections early is paramount to improving patient outcomes, more and more data demonstrate limited courses of antibiotics improve outcomes. Prolonged (10-14 day) courses of antibiotics have remained the standard of care for pneumonia due to gram-negative bacilli (GNR). We aimed to review our GNR VAPs to assess risk factors for recurrent GNR infections.
METHODS
We reviewed trauma patients who developed VAP from 02/2019 through 05/2022. Demographics, injury characteristics, and outcomes were reviewed with a focus on pneumonia details including the cultured pathogen(s), antibiotic(s) used, treatment duration, and presence of recurrent infections. We then compared single episode VAPs to multiple episode VAPs among patients infected by GNRs.
RESULTS
Eleven of the fifty trauma patients admitted to the ICU suffered a VAP caused by a GNR. Of these eleven patients, six experienced a recurrent infection, four of which were caused by and two of which were caused by . Among the patients who received ten days of antibiotic treatment, half suffered a recurrence. Although, there was no difference in the microbiology or antibiotic duration between the recurrences and single episodes.
CONCLUSION
Despite prolonged use of antibiotics, we found that the risk of recurrent or persistent infections was high among patients with VAP due to GNB. Further study is needed to determine optimal treatment to minimize the risk of these recurrences.
KEY MESSAGE
Ventilator-associated pneumonia due to gram-negative bacilli is a rare but high morbidity complication in intensive care units. Despite prolonged duration of therapy, these infections still appear to account for many recurrent infections and further study into optimal therapy is warranted.
PubMed: 37789948
DOI: 10.1016/j.sopen.2023.09.014 -
Nature Communications Sep 2023The selective enzymatic reduction of nitroaliphatic and nitroaromatic compounds to aliphatic amines and amino-, azoxy- and azo-aromatics, respectively, remains a...
The selective enzymatic reduction of nitroaliphatic and nitroaromatic compounds to aliphatic amines and amino-, azoxy- and azo-aromatics, respectively, remains a persisting challenge for biocatalysis. Here we demonstrate the light-powered, selective photoenzymatic synthesis of aliphatic amines and amino-, azoxy- and azo-aromatics from the corresponding nitro compounds. The nitroreductase from Bacillus amyloliquefaciens, in synergy with a photocatalytic system based on chlorophyll, promotes selective conversions of electronically-diverse nitroarenes into a series of aromatic amino, azoxy and azo products with excellent yield (up to 97%). The exploitation of an alternative nitroreductase from Enterobacter cloacae enables the tailoring of a photoenzymatic system for the challenging synthesis of aliphatic amines from nitroalkenes and nitroalkanes (up to 90% yield). This photoenzymatic reduction overcomes the competing bio-Nef reaction, typically hindering the complete enzymatic reduction of nitroaliphatics. The results highlight the usefulness of nitroreductases to create selective photoenzymatic systems for the synthesis of precious chemicals, and the effectiveness of chlorophyll as an innocuous photocatalyst, enabling the use of sunlight to drive the photobiocatalytic reactions.
Topics: Nitro Compounds; Amines; Alkanes; Alkenes; Chlorophyll
PubMed: 37673927
DOI: 10.1038/s41467-023-41194-w -
Croatian Medical Journal Aug 2023Bloodstream infections (BSI) are frequently encountered during extracorporeal membrane oxygenation (ECMO) support. Once septicemia is observed, treatment should be...
Bloodstream infections (BSI) are frequently encountered during extracorporeal membrane oxygenation (ECMO) support. Once septicemia is observed, treatment should be rapid, adequate, and multifaceted, particularly in advanced ECMO configurations. We report on a case of a 60-year-old male patient with acute-on-chronic heart failure due to ischemic cardiomyopathy. The treatment was complicated by cardiogenic shock requiring veno-arterial ECMO support, and, due to persistent pulmonary congestion, an upgrade with an additional left-atrial drainage cannula. After seven days of ECMO support, septicemia with shock ensued. Ex iuvantibus antibiotic treatment was started promptly. We wanted to minimize the likelihood of bacterial biofilm build-up requiring an exchange of the ECMO circuit and cannula, which was expected to be challenging. Therefore, we added a Seraph-100 Microbind affinity blood filter (providing blood purification with the potential for rapid bacterial clearance) to the ECMO circuit. Initial blood cultures tested positive for Enterobacter cloacae. Following a course of Seraph-100 treatment, bacteremia, septicemia, and shock resolved. There was no need for a circuit or cannula exchange. The additional eleven days of ECMO support were uneventful. The patient was successfully bridged to long-term mechanical circulatory support. We believe that the synergistic effect of early implementation of both broad-spectrum antibiotic treatment and blood purification with the potential for rapid bacterial clearance (such as the one provided with the Seraph-100 Microbind affinity blood filter) is crucial in BSI in patients receiving advanced ECMO.
Topics: Male; Humans; Middle Aged; Extracorporeal Membrane Oxygenation; Enterobacter cloacae; Cannula; Sepsis; Bacteremia
PubMed: 37654040
DOI: 10.3325/cmj.2023.64.284 -
BMC Pregnancy and Childbirth Aug 2023Urorectal septum malformation sequence (URSMS) is characterized by incomplete partitioning of the genital, rectal, and urinary tracts, resulting in a severe form of...
BACKGROUND
Urorectal septum malformation sequence (URSMS) is characterized by incomplete partitioning of the genital, rectal, and urinary tracts, resulting in a severe form of anorectal malformation. The partial URSMS, also known as the persistent cloaca, represents a milder variant where a single perineal opening serves as a passage for the urinary, gastrointestinal, and reproductive tracts.
CASE PRESENTATION
We present a rare case of partial URSMS accompanied by duplicated vagina and uterus, hydronephrosis, ascites, and anal atresia.
CONCLUSIONS
This case report describes the sonographic findings at different stages of pregnancy and their changes throughout gestation.
Topics: Female; Pregnancy; Humans; Pregnancy Trimester, First; Ultrasonography; Ascites; Hydronephrosis; Ultrasonography, Prenatal
PubMed: 37620796
DOI: 10.1186/s12884-023-05939-1 -
Nature Communications Aug 2023Infections caused by metallo-beta-lactamase-producing organisms (MBLs) are a global health threat. Our understanding of transmission dynamics and how MBLs establish...
Infections caused by metallo-beta-lactamase-producing organisms (MBLs) are a global health threat. Our understanding of transmission dynamics and how MBLs establish endemicity remains limited. We analysed two decades of bla evolution in a hospital using sequence data from 270 clinical and environmental isolates (including 169 completed genomes) and identified the bla gene across 7 Gram-negative genera, 68 bacterial strains and 7 distinct plasmid types. We showed how an initial multi-species outbreak of conserved IncC plasmids (95 genomes across 37 strains) allowed endemicity to be established through the ability of bla to disseminate in successful strain-genetic setting pairs we termed propagators, in particular Serratia marcescens and Enterobacter hormaechei. From this reservoir, bla persisted through diversification of genetic settings that resulted from transfer of bla plasmids between bacterial hosts and of the integron carrying bla between plasmids. Our findings provide a framework for understanding endemicity and spread of MBLs and may have broader applicability to other carbapenemase-producing organisms.
Topics: Integrons; beta-Lactamases; Bacterial Proteins; Plasmids; Serratia marcescens; Carbapenems; Genomics; Microbial Sensitivity Tests; Anti-Bacterial Agents
PubMed: 37553339
DOI: 10.1038/s41467-023-39915-2 -
The Science of the Total Environment Nov 2023Free-living amoebae (FLA) are ubiquitous protozoa mainly found in aquatic environments. They are well-known reservoirs and vectors for the transmission of...
Bacterial microbiota management in free-living amoebae (Heterolobosea lineage) isolated from water: The impact of amoebae identity, grazing conditions, and passage number.
Free-living amoebae (FLA) are ubiquitous protozoa mainly found in aquatic environments. They are well-known reservoirs and vectors for the transmission of amoeba-resistant bacteria (ARB), most of which are pathogenic to humans. Yet, the natural bacterial microbiota associated with FLA remains largely unknown. Herein, we characterized the natural bacterial microbiota of different FLA species isolated from recreational waters in Guadeloupe. Monoxenic cultures of Naegleria australiensis, Naegleria sp. WTP3, Paravahlkampfia ustiana and Vahlkampfia sp. AK-2007 (Heterolobosea lineage) were cultivated under different grazing conditions, during successive passages. The whole bacterial microbiota of the waters and the amoebal cysts was characterized using 16S rRNA gene metabarcoding. The culturable subset of ARB was analyzed by mass spectrometry (MALDI-TOF MS), conventional 16S PCR, and disk diffusion method (to assess bacterial antibiotic resistance). Transmission electron microscopy was used to locate the ARB inside the amoebae. According to alpha and beta-diversity analyses, FLA bacterial microbiota were significantly different from the ones of their habitat. While Vogesella and Aquabacterium genera were detected in water, the most common ARB belonged to Pseudomonas, Bosea, and Escherichia/Shigella genera. The different FLA species showed both temporary and permanent associations with differentially bacterial taxa, suggesting host specificity. These associations depend on the number of passages and grazing conditions. Additionally, Naegleria, Vahlkampfia and Paravahlkampfia cysts were shown to naturally harbor viable bacteria of the Acinetobacter, Escherichia, Enterobacter, Pseudomonas and Microbacterium genera, all being pathogenic to humans. To our knowledge, this is the first time Paravahlkampfia and Vahlkampfia have been demonstrated as hosts of pathogenic ARB in water. Globally, the persistence of these ARB inside resistant cysts represents a potential health risk. To ensure the continued safety of recreational waters, it is crucial to (i) regularly control both the amoebae and their ARB and (ii) improve knowledge on amoebae-bacteria interactions to establish better water management protocols.
Topics: Humans; Water; RNA, Ribosomal, 16S; Angiotensin Receptor Antagonists; Angiotensin-Converting Enzyme Inhibitors; Amoeba; Bacteria; Microbiota
PubMed: 37506913
DOI: 10.1016/j.scitotenv.2023.165816