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American Journal of Infection Control Mar 2024Aquatic opportunistic pathogen Aeromonas hydrophila, known to persist in low-nutrient chlorinated waters, can cause life-threatening infections. Two intensive care units...
BACKGROUND
Aquatic opportunistic pathogen Aeromonas hydrophila, known to persist in low-nutrient chlorinated waters, can cause life-threatening infections. Two intensive care units experienced a cluster of Aeromonas infections following outdoor temperature spikes coinciding with recurrent plumbing issues, with fatalities due to severe underlying comorbidities co-occurring with extensively-drug resistant (XDR) Aeromonas.
METHODS
We investigated this cluster using whole genome sequencing to assess genetic relatedness of isolates and identify antimicrobial resistance determinants. Three A. hydrophila were isolated from patients staying in or adjacent to rooms with plumbing issues during or immediately after periods of elevated outdoor temperatures. Sinks and faucets were swabbed for culture.
RESULTS
All A. hydrophila clinical isolates exhibited carbapenem resistance but were not genetically related. Diverse resistance determinants corresponding to extensively-drug resistant were found, including co-occurring KPC-3 and VIM-2, OXA-232, and chromosomal CphA-like carbapenemase genes, contributing to major treatment challenges. All 3 patients were treated with multiple antibiotic regimens to overcome various carbapenemase classes and expired due to underlying comorbidities. Environmental culture yielded no Aeromonas.
CONCLUSIONS
While the investigation revealed no singular source of contamination, it supports a possible link between plumbing issues, elevated outdoor temperatures and incidence of nosocomial Aeromonas infections. The diversity of carbapenemase genes detected in these wastewater-derived Aeromonas warrants heightened infection prevention precautions during periods of plumbing problems especially with heat waves.
Topics: Humans; Aeromonas hydrophila; Sanitary Engineering; Cross Infection; Hot Temperature; beta-Lactamases; Aeromonas; Anti-Bacterial Agents; Microbial Sensitivity Tests; Bacterial Proteins
PubMed: 37778710
DOI: 10.1016/j.ajic.2023.09.013 -
Microbial Genomics May 2024is an emerging human enteric pathogen. However, the genomic features and virulence genes of strains from human gastroenteritis and other sources have not been fully...
Analysis of global genomes revealed that strains carrying T6SS are more common in human gastroenteritis than in environmental sources and are often phylogenetically related.
is an emerging human enteric pathogen. However, the genomic features and virulence genes of strains from human gastroenteritis and other sources have not been fully elucidated. Here, we conducted a genomic analysis of 565 global strains isolated from different sources, including 261 strains isolated from faecal samples of gastroenteritis patients, of which 18 genomes were sequenced in this study. The presence of bacterial virulence genes and secretion systems in strains from different sources was compared, and the phylogenetic relationship of strains was assessed based on the core genome. The complete genome of strain A20-9 isolated from a gastroenteritis patient was obtained in this study, from which 300 putative virulence factors and a T4SS-encoding plasmid, pAC, were identified. Genes encoding T4SS were also identified in a novel genomic island, ACI-1, from other T4SS-positive strains. The prevalence of T4SS was significantly lower in strains from gastroenteritis patients than in environmental strains (3 %, <0.0001 vs 14 %, <0.01). Conversely, the prevalence of T6SS was significantly higher in strains isolated from gastroenteritis patients than in environmental strains (25 %, <0.05 vs 13 %, <0.01). Four phylogenetic clusters were formed based on the core genome of 565 . strains, and strains carrying T6SS often showed close phylogenetic relationships. T3SS, aerolysin and thermostable cytotonic enterotoxin were absent in all 565 . strains. Our findings provide novel information on the genomic features of and suggest that T6SS may play a role in -induced human gastroenteritis.
Topics: Gastroenteritis; Humans; Phylogeny; Genome, Bacterial; Aeromonas caviae; Virulence Factors; Type VI Secretion Systems; Feces; Gram-Negative Bacterial Infections; Genomic Islands; Plasmids
PubMed: 38814176
DOI: 10.1099/mgen.0.001258 -
International Journal of Molecular... Jun 2024Grass Carp Reovirus (GCRV) and (Ah) are the causative agents of haemorrhagic disease in grass carp. This study aimed to investigate the molecular mechanisms and immune... (Comparative Study)
Comparative Study
Grass Carp Reovirus (GCRV) and (Ah) are the causative agents of haemorrhagic disease in grass carp. This study aimed to investigate the molecular mechanisms and immune responses at the miRNA, mRNA, and protein levels in grass carp kidney cells (CIK) infected by Grass Carp Reovirus (GCRV, NV) and (Bacteria, NB) to gain insight into their pathogenesis. Within 48 h of infection with Grass Carp Reovirus (GCRV), 99 differentially expressed microRNA (DEMs), 2132 differentially expressed genes (DEGs), and 627 differentially expressed proteins (DEPs) were identified by sequencing; a total of 92 DEMs, 3162 DEGs, and 712 DEPs were identified within 48 h of infection with . It is worth noting that most of the DEGs in the NV group were primarily involved in cellular processes, while most of the DEGs in the NB group were associated with metabolic pathways based on KEGG enrichment analysis. This study revealed that the mechanism of a grass carp haemorrhage caused by GCRV infection differs from that caused by the infection. An important miRNA-mRNA-protein regulatory network was established based on comprehensive transcriptome and proteome analysis. Furthermore, 14 DEGs and 6 DEMs were randomly selected for the verification of RNA/small RNA-seq data by RT-qPCR. Our study not only contributes to the understanding of the pathogenesis of grass carp CIK cells infected with GCRV and but also serves as a significant reference value for other aquatic animal haemorrhagic diseases.
Topics: Aeromonas hydrophila; Animals; Carps; MicroRNAs; Transcriptome; RNA, Messenger; Reoviridae; Proteomics; Fish Diseases; Gene Expression Profiling; Gram-Negative Bacterial Infections; Cell Line; Reoviridae Infections; Gene Regulatory Networks
PubMed: 38928143
DOI: 10.3390/ijms25126438 -
Anais Da Academia Brasileira de Ciencias 2024The growing increase in the fish farming sector has favored the establishment of bacterial outbreaks caused by Aeromonas hydrophila in several species. The hexane...
The growing increase in the fish farming sector has favored the establishment of bacterial outbreaks caused by Aeromonas hydrophila in several species. The hexane extract of Hesperozygis ringens (HEHR) (Lamiaceae) leaves increased the survival rate of silver catfish (Rhamdia quelen) experimentally infected by A. hydrophila. However, it is noteworthy that no reports have been found on the possible mechanisms of action of this extract in infected fish. This study aimed to evaluate the effect of the HEHR, administered through single immersion bath, on lipid peroxidation and antioxidant defenses in muscle and liver tissue of silver catfish challenged with A. hydrophila. The results showed that the oxidative status of silver catfish was altered, although oxidative stress was not triggered during the experiment. HEHR at 30 mg/L (HEHR30) was not characterized as a pro-oxidant agent in the presence of infection, unlike florfenicol and HEHR at 15 mg/L treatments in some cases. In short, HEHR30 provided an important increase in hepatic catalase activity, characterizing one of the possible mechanisms involved in the greater survival of fish experimentally infected by A. hydrophila. Additionally, HEHR30 did not induce lipid peroxidation, nor reduced antioxidant defenses of silver catfish infected or not by A. hydrophila.
Topics: Animals; Aeromonas hydrophila; Antioxidants; Catfishes; Hexanes; Immersion; Lamiaceae; Oxidation-Reduction; Fish Diseases; Gram-Negative Bacterial Infections
PubMed: 38597489
DOI: 10.1590/0001-3765202420230188 -
Frontiers in Immunology 2024Red blood cells (RBCs), also known as erythrocytes, are underestimated in their role in the immune system. In mammals, erythrocytes undergo maturation that involves the...
Erythrocytes of the common carp are immune sentinels that sense pathogen molecular patterns, engulf particles and secrete pro-inflammatory cytokines against bacterial infection.
INTRODUCTION
Red blood cells (RBCs), also known as erythrocytes, are underestimated in their role in the immune system. In mammals, erythrocytes undergo maturation that involves the loss of nuclei, resulting in limited transcription and protein synthesis capabilities. However, the nucleated nature of non-mammalian RBCs is challenging this conventional understanding of RBCs. Notably, in bony fishes, research indicates that RBCs are not only susceptible to pathogen attacks but express immune receptors and effector molecules. However, given the abundance of RBCs and their interaction with every physiological system, we postulate that they act in surveillance as sentinels, rapid responders, and messengers.
METHODS
We performed a series of experiments with RBCs exposed to , as well as laboratory infections using different concentrations of bacteria.
RESULTS
qPCR revealed that RBCs express genes of several inflammatory cytokines. Using cyprinid-specific antibodies, we confirmed that RBCs secreted tumor necrosis factor alpha (TNFα) and interferon gamma (IFNγ). In contrast to these indirect immune mechanisms, we observed that RBCs produce reactive oxygen species and, through transmission electron and confocal microscopy, that RBCs can engulf particles. Finally, RBCs expressed and upregulated several putative toll-like receptors, including and , in response to infection .
DISCUSSION
Overall, the RBC repertoire of pattern recognition receptors, their secretion of effector molecules, and their swift response make them immune sentinels capable of rapidly detecting and signaling the presence of foreign pathogens. By studying the interaction between a bacterium and erythrocytes, we provide novel insights into how the latter may contribute to overall innate and adaptive immune responses of teleost fishes.
Topics: Animals; Carps; Erythrocytes; Cytokines; Aeromonas hydrophila; Gram-Negative Bacterial Infections; Fish Diseases; Phagocytosis; Pathogen-Associated Molecular Pattern Molecules; Immunity, Innate
PubMed: 38947329
DOI: 10.3389/fimmu.2024.1407237 -
Fish & Shellfish Immunology Apr 2024Aeromonas salmonicida is one of the most harmful pathogens in finfish aquaculture worldwide. Immunostimulants such as β-glucans are used to enhance the immunity of...
Transcriptomic analysis of turbot (Scophthalmus maximus) treated with zymosan a reveals that lncRNAs and inflammation-related genes mediate the protection conferred against Aeromonas salmonicida.
Aeromonas salmonicida is one of the most harmful pathogens in finfish aquaculture worldwide. Immunostimulants such as β-glucans are used to enhance the immunity of cultured fish. However, their effects on fish physiology are not completely understood. In the present work, we evaluated the effect of a single intraperitoneal (ip) injection of zymosan A on fish survival against A. salmonicida infection. A single administration of this compound protected fish against A. salmonicida challenge and reduce the bacterial load in the head kidney one week after its administration. Transcriptome analyses of head kidney samples revealed several molecular mechanisms involved in the protection conferred by zymosan A and their regulation by long noncoding RNAs. The transcriptome profile of turbot exposed only to zymosan A was practically unaltered one week after ip injection. However, the administration of this immunostimulant induced significant transcriptomic changes once the fish were in contact with the bacteria and increased the survival of the infected turbot. Our results suggest that the restraint of the infection-induced inflammatory response, the management of apoptotic cell death, cell plasticity and cellular processes involving cytoskeleton dynamics support the protective effects of zymosan A. All this information provides insights on the cellular and molecular mechanisms involved in the protective effects of this widely used immunostimulant.
Topics: Animals; Zymosan; Aeromonas salmonicida; RNA, Long Noncoding; Fish Diseases; Flatfishes; Inflammation; Gene Expression Profiling; Adjuvants, Immunologic; Gram-Negative Bacterial Infections
PubMed: 38369070
DOI: 10.1016/j.fsi.2024.109456