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The Pediatric Infectious Disease Journal Feb 2024We evaluated whether the quantification of IgG to pneumococcal capsular polysaccharides is an accurate diagnostic test for pneumococcal infection in children with...
Evaluation of Acute and Convalescent Antibody Concentration Against Pneumococcal Capsular Polysaccharides for the Diagnosis of Pneumococcal Infection in Children with Community-Acquired Pneumonia.
We evaluated whether the quantification of IgG to pneumococcal capsular polysaccharides is an accurate diagnostic test for pneumococcal infection in children with pneumonia in Nepal. Children with pneumococcal pneumonia did not have higher convalescent, or higher fold change, IgG to pneumococcal polysaccharides than children with other causes of pneumonia. Caution is needed in interpreting antibody responses in pneumococcal infections.
Topics: Humans; Antibodies, Bacterial; Child, Preschool; Polysaccharides, Bacterial; Immunoglobulin G; Infant; Streptococcus pneumoniae; Pneumonia, Pneumococcal; Community-Acquired Infections; Male; Female; Child; Nepal; Bacterial Capsules
PubMed: 38758207
DOI: 10.1097/INF.0000000000004185 -
MSystems May 2024The emergence of nosocomial infections caused by hypervirulent and carbapenem-resistant (hv-CRKP) has become a significant public health challenge. The genetic traits...
The emergence of nosocomial infections caused by hypervirulent and carbapenem-resistant (hv-CRKP) has become a significant public health challenge. The genetic traits of virulence and resistance plasmids in hv-CRKP have been extensively studied; however, research on the adaptive evolution strategies of clinical strains inside the host was scarce. This study aimed to understand the effects of antibiotic treatment on the phenotype and genotype characteristics of hv-CRKP. We investigated the evolution of hv-CRKP strains isolated from the same patient to elucidate the transition between hospital invasion and colonization. A comparative genomics analysis was performed to identify single nucleotide polymorphisms in the promoter. Subsequent validation through RNA-seq and gene deletion confirmed that distinct promoter sequences exert control over the mucoid phenotype. Additionally, biofilm experiments, cell adhesion assays, and animal infection models were conducted to illuminate the influence of promoter diversity on virulence changes. We demonstrated that the P12T and P11T promoters of possess strong activity, which leads to the evolution of CRKP into infectious and virulent strains. Meanwhile, the specific sequence of polyT motifs in the promoter led to a decrease in the lethality of hv-CRKP and enhanced cell adhesion and colonization. To summarize, the promoter of hv-CRKP is utilized to control capsule production, thereby modifying pathogenicity to better suit the host's ecological environment.IMPORTANCEThe prevalence of hospital-acquired illness caused by hypervirulent carbapenem-resistant (hv-CRKP) is significant, leading to prolonged antibiotic treatment. However, there are few reports on the phenotypic changes of hv-CRKP in patients undergoing antibiotic treatment. We performed a comprehensive examination of the genetic evolutionary traits of hv-CRKP obtained from the same patient and observed variations in the promoter sequences of the virulence factor . The strong activity of the promoter sequences P11T and P12T enhances the consistent production of capsule polysaccharides, resulting in an invasive strain. Conversely, weak promoter activity of P9T and P10T is advantageous for exposing pili, hence improving bacterial cell attachment ability and facilitating bacterial colonization. This finding also explains the confusion of some clinical strains carrying wild-type but exhibiting a low mucoid phenotype. This adaptive alteration facilitates the dissemination of within the hospital setting.
PubMed: 38752758
DOI: 10.1128/msystems.01363-23 -
Plastic and Reconstructive Surgery.... May 2024Capsular contracture (CC) is a leading cause of morbidity in implant-based breast surgery. Implant surface texture has been implicated in CC development, yet its...
BACKGROUND
Capsular contracture (CC) is a leading cause of morbidity in implant-based breast surgery. Implant surface texture has been implicated in CC development, yet its etiopathogenesis remains unclear. We conducted a systematic review to determine the influence of implant surface texture on cellular and molecular mechanisms involved in the etiopathogenesis of CC.
METHODS
A systematic review of the MEDLINE, Embase, Web of Science, and Scopus databases was completed to examine the influence of implant texture on cellular and molecular pathways leading to CC. Excluded articles were reviews and those examining solely the clinical presentation of CC.
RESULTS
Development of CC includes prolonged inflammation, increased myofibroblast density, parallel arrangement of collagen fibers, and biofilm formation. When compared with textured implants, smooth implants are associated with reduction in parallel collagen, capsule thickness, and sheer frictional force. Microtextured implants trigger a reduced macrophage response and decreased fibroblast activation as compared with smooth and macrotextured surfaces. Bacterial counts on microtextured and smooth surfaces are significantly lower than that of macrotextured surfaces. Both micro- and macrotextured implants have increased matrix metalloproteinases and activation of tumor necrosis factor α pathway, with increased activation of the transforming growth factor β1 pathway relative to smooth implants.
CONCLUSIONS
Implant surface texture alters the cellular and molecular mechanisms in the chronic inflammatory process leading to CC. Given the complex biological system of cellular and molecular events in CC, a mathematical model integrating these influences may be optimal to deduce the etiopathogenesis.
PubMed: 38746946
DOI: 10.1097/GOX.0000000000005802 -
BioRxiv : the Preprint Server For... May 2024(Kpn) is the fourth leading cause of infection-related deaths globally, yet little is known about human antibody responses to invasive Kpn. In this study, we sought to...
BACKGROUND
(Kpn) is the fourth leading cause of infection-related deaths globally, yet little is known about human antibody responses to invasive Kpn. In this study, we sought to determine whether the O-specific polysaccharide (OPS) antigen, a vaccine candidate, is immunogenic in humans with Kpn bloodstream infection (BSI). We also sought to define the cross-reactivity of human antibody responses among structurally related Kpn OPS subtypes and to assess the impact of capsule production on OPS-targeted antibody binding and function.
METHODS
We measured plasma antibody responses to OPS (and MrkA, a fimbrial protein) in a cohort of patients with Kpn BSI and compared these with controls, including a cohort of healthy individuals and a cohort of individuals with BSI. We performed flow cytometry to measure the impact of Kpn capsule production on whole cell antibody binding and complement deposition, utilizing patient isolates with variable levels of capsule production and isogenic capsule-deficient strains derived from these isolates.
FINDINGS
We enrolled 69 patients with Kpn BSI. Common OPS serotypes accounted for 57/69 (83%) of infections. OPS was highly immunogenic in patients with Kpn BSI, and peak OPS-IgG antibody responses in patients were 10 to 30-fold higher than antibody levels detected in healthy controls, depending on the serotype. There was significant cross-reactivity among structurally similar OPS subtypes, including the O1v1/O1v2, O2v1/O2v2 and O3/O3b subtypes. Physiological amounts of capsule produced by both hyperencapsulated and non-hyperencapsulated Kpn significantly inhibited OPS-targeted antibody binding and function.
INTERPRETATION
OPS was highly immunogenic in patients with Kpn BSI, supporting its potential as a candidate vaccine antigen. The strong cross-reactivity observed between similar OPS subtypes in humans with Kpn BSI suggests that it may not be necessary to include all subtypes in an OPS-based vaccine. However, these observations are tempered by the fact that capsule production, even in non-highly encapsulated strains, has the potential to interfere with OPS antibody binding. This may limit the effectiveness of vaccines that exclusively target OPS.
FUNDING
National Institute of Allergy and Infectious Diseases at the National Institutes of Health.
RESEARCH IN CONTEXT
Despite the potential of O-specific polysaccharide (OPS) as a vaccine antigen against (Kpn), the immunogenicity of OPS in humans remains largely unstudied, creating a significant knowledge gap with regard to vaccine development. A search of PubMed for publications up to March 18, 2024, using the terms " " and "O-specific polysaccharide" or "O-antigen" or "lipopolysaccharide" revealed no prior studies addressing OPS antibody responses in humans with Kpn bloodstream infections (BSI). One prior study evaluated antibody response to a single lipopolysaccharide (which contains one subtype of OPS) in humans with invasive Kpn infection; however, in this study OPS typing of the infecting strains and target antigen were not described. Our investigation into OPS immunogenicity in a human cohort marks a significant advance. Analyzing plasma antibody responses in 69 patients with Kpn BSI, we found OPS to be broadly immunogenic across all the types and subtypes examined, and there was significant cross-reactivity among structurally related OPS antigens. We also demonstrated that Kpn capsule production inhibit OPS antibody binding and the activation of complement on the bacterial surface, even in classical Kpn strains expressing lower levels of capsule. While the immunogenicity and broad cross-reactivity of OPS in humans with Kpn BSI suggests it is a promising vaccine candidate, the obstruction of OPS antibody binding and engagement by physiologic levels of Kpn capsule underscores the potential limitations of an exclusively OPS-antigen based vaccine for Kpn. Our study provides insights for the strategic development of vaccines aimed at combating Kpn infections, an important antimicrobial resistant pathogen.
PubMed: 38746292
DOI: 10.1101/2024.05.01.591958 -
Virulence Dec 2024ST11 is the most common lineage among carbapenem-resistant (CRKP) infections in Asia. Diverse morphotypes resulting from genetic mutations are associated with...
ST11 is the most common lineage among carbapenem-resistant (CRKP) infections in Asia. Diverse morphotypes resulting from genetic mutations are associated with significant differences in microbial characteristics among isolates. Here, we investigated the genetic determinants and critical characteristics associated with distinct morphotypes of ST11 CRKP. An ST11-KL47 CRKP isolate carrying a pLVPK-like virulence plasmid was isolated from a patient with a bloodstream infection; the isolate had the "mcsw" morphotype. Two distinct morphotypes ("ntrd" and "msdw") were derived from this strain during passage. Whole genome sequencing was used to identify mutations that cause the distinct morphotypes of ST11 CRKP. Transmission electron microscopy, antimicrobial susceptibility tests, growth assays, biofilm formation, virulence assays, membrane permeability assays, and RNA-seq analysis were used to investigate the specific characteristics associated with different morphotypes of ST11 CRKP. Compared with the parental mcsw morphotype, the ntrd morphotype resulted from mutation of genes involved in capsular polysaccharide biosynthesis (, , and ), a result validated by gene knockout experiments. This morphotype showed capsule deficiency and lower virulence potential, but higher biofilm production. By contrast, the msdw morphotype displayed competition deficiency and increased susceptibility to chlorhexidine and polymyxin B. Further analyses indicated that these characteristics were caused by interruption of the sigma factor gene by insertion mutations and deletion of the gene, which attenuated membrane integrity presumably by downregulating the phage shock protein operon. These data expand current understanding of genetic, virulence, and antimicrobial resistance characteristics associated with distinct morphotypes in ST11 CRKP.
Topics: Klebsiella pneumoniae; Virulence; Klebsiella Infections; Humans; Anti-Bacterial Agents; Biofilms; Carbapenems; Microbial Sensitivity Tests; Animals; Carbapenem-Resistant Enterobacteriaceae; Mice; Mutation; Whole Genome Sequencing; Plasmids; Drug Resistance, Bacterial
PubMed: 38736039
DOI: 10.1080/21505594.2024.2349768 -
Frontiers in Cellular and Infection... 2024
Topics: Bacteria; Polymers; Humans
PubMed: 38725450
DOI: 10.3389/fcimb.2024.1415799 -
International Journal of Nanomedicine 2024Surgical site infections pose a significant challenge for medical services. Systemic antibiotics may be insufficient in preventing bacterial biofilm development. With...
PURPOSE
Surgical site infections pose a significant challenge for medical services. Systemic antibiotics may be insufficient in preventing bacterial biofilm development. With the local administration of antibiotics, it is easier to minimize possible complications, achieve drugs' higher concentration at the injured site, as well as provide their more sustained release. Therefore, the main objective of the proposed herein studies was the fabrication and characterization of innovative hydrogel-based composites for local vancomycin (VAN) therapy.
METHODS
Presented systems are composed of ionically gelled chitosan particles loaded with vancomycin, embedded into biomimetic collagen/chitosan/hyaluronic acid-based hydrogels crosslinked with genipin and freeze-dried to serve in a flake/disc-like form. VAN-loaded carriers were characterized for their size, stability, and encapsulation efficiency (EE) using dynamic light scattering technique, zeta potential measurements, and UV-Vis spectroscopy, respectively. The synthesized composites were tested in terms of their physicochemical and biological features.
RESULTS
Spherical structures with sizes of about 200 nm and encapsulation efficiencies reaching values of approximately 60% were obtained. It was found that the resulting particles exhibit stability over time. The antibacterial activity of the developed materials against was established. Moreover, in vitro cell culture study revealed that the surfaces of all prepared systems are biocompatible as they supported the proliferation and adhesion of the model MG-63 cells. In addition, we have demonstrated significantly prolonged VAN release while minimizing the initial burst effect for the composites compared to bare nanoparticles and verified their desired physicochemical features during swellability, and degradation experiments.
CONCLUSION
It is expected that the developed herein system will enable direct delivery of the antibiotic at an exposed to infections surgical site, providing drugs sustained release and thus will reduce the risk of systemic toxicity. This strategy would both inhibit biofilm formation and accelerate the healing process.
Topics: Vancomycin; Anti-Bacterial Agents; Hydrogels; Staphylococcus aureus; Humans; Chitosan; Hyaluronic Acid; Drug Carriers; Collagen; Particle Size; Drug Liberation; Surgical Wound Infection; Microbial Sensitivity Tests; Biofilms
PubMed: 38720939
DOI: 10.2147/IJN.S443051 -
Veterinary Research May 2024Klebsiella pneumoniae has become one of the most intractable gram-negative pathogens infecting humans and animals due to its severe antibiotic resistance. Bacteriophages...
Klebsiella pneumoniae has become one of the most intractable gram-negative pathogens infecting humans and animals due to its severe antibiotic resistance. Bacteriophages and protein products derived from them are receiving increasing amounts of attention as potential alternatives to antibiotics. In this study, we isolated and investigated the characteristics of a new lytic phage, P1011, which lyses K5 K. pneumoniae specifically among 26 serotypes. The K5-specific capsular polysaccharide-degrading depolymerase dep1011 was identified and expressed. By establishing murine infection models using bovine strain B16 (capable of supporting phage proliferation) and human strain KP181 (incapable of sustaining phage expansion), we explored the safety and efficacy of phage and dep1011 treatments against K5 K. pneumoniae. Phage P1011 resulted in a 60% survival rate of the mice challenged with K. pneumoniae supporting phage multiplication, concurrently lowering the bacterial burden in their blood, liver, and lungs. Unexpectedly, even when confronted with bacteria impervious to phage multiplication, phage therapy markedly decreased the number of viable organisms. The protective efficacy of the depolymerase was significantly better than that of the phage. The depolymerase achieved 100% survival in both treatment groups regardless of phage propagation compatibility. These findings indicated that P1011 and dep1011 might be used as potential antibacterial agents to control K5 K. pneumoniae infection.
Topics: Animals; Klebsiella pneumoniae; Mice; Klebsiella Infections; Bacteriophages; Disease Models, Animal; Phage Therapy; Female; Glycoside Hydrolases; Cattle
PubMed: 38715095
DOI: 10.1186/s13567-024-01311-z -
Scientific Reports Apr 2024The Capsule for Sampling (CapSa) is an ingestible capsule that collects small intestine content while transiting through the natural digestive pathway. In this study, 14...
The Capsule for Sampling (CapSa) is an ingestible capsule that collects small intestine content while transiting through the natural digestive pathway. In this study, 14 Swiss Large White pigs weighing less than 12 kg (Category < 12 kg) and 12 weighing between 12 and 20 kg (Category [12-20 kg]) were given two CapSas and monitored for three days. The animals were euthanized for post-mortem sampling, allowing us to directly obtain gut microbiota samples from the gastrointestinal tract. This post-mortem approach enabled a direct comparison between the microbial content from the gut and the samples collected via the CapSas, and it also facilitated precise identification of the CapSas' sampling sites within the gastrointestinal tract. For the category under 12 kg, only 2.3% of the administered CapSas were recovered from the feces. In contrast, in the 12-20 kg category, 62.5% of the CapSas were successfully retrieved from the feces within 48 h. Of these recovered CapSas, 73.3%-equating to 11 capsules from eight pigs-had a pH > 5.5 and were therefore selected for microbiome analysis. Bacterial composition of the CapSas was compared with that of the three segments of the small intestine, the large intestine and feces of the corresponding pig. The results were tested using a PERMANOVA model (Adonis) including sample type as a factor, and then pairwise comparisons were made. The bacterial composition found in the CapSas differed from that of the large intestine and feces (P < 0.01), while it did not differ from the first segment of the small intestine (P > 0.10). This study provides evidence that the CapSa effectively samples the intestinal microbiota from the upper section of the small intestine in post-weaning pigs. Furthermore, it was found that the collection of CapSas could only be successfully achieved in pigs classified within the heavier weight category.
Topics: Animals; Intestine, Small; Swine; Gastrointestinal Microbiome; Weaning; Feces; Bacteria
PubMed: 38693207
DOI: 10.1038/s41598-024-59950-3 -
Frontiers in Microbiology 2024A rapid increase in antimicrobial resistant bacterial infections around the world is causing a global health crisis. The Gram-negative bacterium is categorized as a...
A rapid increase in antimicrobial resistant bacterial infections around the world is causing a global health crisis. The Gram-negative bacterium is categorized as a Priority 1 pathogen for research and development of new antimicrobials by the World Health Organization due to its numerous intrinsic antibiotic resistance mechanisms and ability to quickly acquire new resistance determinants. Specialized phage enzymes, called depolymerases, degrade the bacterial capsule polysaccharide layer and show therapeutic potential by sensitizing the bacterium to phages, select antibiotics, and serum killing. The functional domains responsible for the capsule degradation activity are often found in the tail fibers of select phages. To further explore the functional domains associated with depolymerase activity, tail-associated proteins of 71 sequenced and fully characterized phages were identified from published literature and analyzed for functional domains using InterProScan. Multisequence alignments and phylogenetic analyses were conducted on the domain groups and assessed in the context of noted halo formation or depolymerase characterization. Proteins derived from phages noted to have halo formation or a functional depolymerase, but no functional domain hits, were modeled with AlphaFold2 Multimer, and compared to other protein models using the DALI server. The domains associated with depolymerase function were pectin lyase-like (SSF51126), tailspike binding (cd20481), (Trans)glycosidases (SSF51445), and potentially SGNH hydrolases. These findings expand our knowledge on phage depolymerases, enabling researchers to better exploit these enzymes for therapeutic use in combating the antimicrobial resistance crisis.
PubMed: 38690360
DOI: 10.3389/fmicb.2024.1230997