Prevalent Serotypes Research Articles

A multi-epitope subunit vaccine providing broad cross-protection against diverse serotypes of Streptococcus suis.

Streptococcus suis infection represents a major challenge in pig farming and public health due to its zoonotic potential and diverse serotypes, while existing vaccines lack effective cross-protection. This study employed reverse vaccinology and immunoinformatics to identify 8 conserved proteins across 11 prevalent serotypes of S. suis. 16 candidate epitopes were selected to design three multi-epitope antigens against S. suis (designated as MEASs), which fused with a dendritic cell-targeting peptide to improve antigen presentation in host. Purified MEASs displayed favorable cross-reactogenicity against 29 serotype-specific antiserums. Robust humoral and cellular immune responses can be induced by MEAS 1 and MEAS 3 in a mouse model, which provided substantial protection against virulent strains from two different serotypes. In particular, their immune serums exhibited positive opsonization effects within bloodstream and macrophage phagocytosis. Taken together, we identified two promising MEASs with excellent cross-protection, offering potential in preventing S. suis infections in a mouse model.

Development and characterisation of a 13-plex binding assay to detect Shigella antibodies in human samples

Abstract Shigella is the leading bacterial cause of diarrhea worldwide, with increasing levels of antibiotic resistance. The greatest burden is among children under five in low- and middle-income countries, and efforts are ongoing to develop vaccines against this pathogen. One of the challenges associated with the development of a vaccine against Shigella is the need for a multivalent vaccine covering the most prevalent Shigella serotypes. Epidemiological studies to better understand the prevalence of the different Shigella serotypes and inform vaccination schedules are very useful, together with clinical data showing the ability of vaccines to elicit cross-reactive antibodies. Here, we set up a Luminex-based method able to reproducibly measure antibodies specific to 13 different Shigella antigens in human sera. This method will allow to rapidly collect large amounts of data from analysis of serum samples from vaccinated subjects or people naturally exposed to Shigella, supporting the development of a vaccine against this disease.

Non-invasive Streptococcus pneumoniae infections are associated with different serotypes than invasive infections, Belgium, 2020 to 2023.

BackgroundDespite widely implemented pneumococcal vaccination programmes, Streptococcus pneumoniae remains a global risk for human health. Streptococcus pneumoniae can cause invasive (IPD) or non-invasive pneumococcal disease (NIPD). Surveillance is mainly focusing on IPD, assessing the full impact of pneumococcal vaccination programmes on pneumococcal disease is challenging.AimWe aimed to prospectively investigate serotype distribution and antimicrobial resistance (AMR) of S. pneumoniae isolates from patients with NIPD and compare with data on IPD isolates and with a 2007-2008 dataset on NIPD.MethodsBetween September 2020 and April 2023, we collected isolates and patient data from patients with NIPD from 23 clinical laboratories in Belgium. Capsular typing was performed by a validated Fourier-Transform Infrared spectroscopic method, and AMR was assessed with broth microdilution, using the European Committee on Antimicrobial Susceptibility Testing (EUCAST) clinical breakpoints.ResultsWe received S. pneumoniae isolates from 1,008 patients with lower respiratory tract infections (n = 760), otitis media (n = 190) and sinusitis (n = 58). Serotype 3 was the most prevalent serotype among the NIPD isolates. Serotypes not included in the 20-valent pneumococcal conjugate vaccine (PCV20) were significantly more common among the NIPD than among the IPD isolates. Antimicrobial resistance levels were significantly higher among the NIPD isolates (n = 539; 2020-2022) compared with the IPD isolates (n = 2,344; 2021-2022). Resistance to several β-lactam antimicrobials had increased significantly compared with 15 years before.ConclusionsThe NIPD isolates were strongly associated with non-vaccine serotypes and with increased AMR levels. This underlines the importance of continued NIPD surveillance for informed policy making on vaccination programmes.

Streptococcus pneumoniae serotype distribution in Bangladeshi under-fives with community-acquired pneumonia pre-10-valent pneumococcal conjugate vaccination

BackgroundStreptococcus pneumoniae is the most frequent causative pathogen of bacterial pneumonia in children worldwide. Bangladesh introduced the 10-valent pneumococcal conjugate vaccine (PCV10) in their national immunization program for infants in 2015. We assessed its potential coverage in under-fives with community-acquired pneumonia (CAP) in the years before PCV10 was introduced.MethodsA total of 1502 childhood pneumonia cases (< 5 year olds living in the urban section Kamalapur, Dhaka) were enrolled between 2011 and 2013. Acute phase and late (convalescent) serum samples were collected from 1380 cases. Serotype-specific pneumococcal antibody concentrations were measured using a 25-plex immunoassay panel. Pneumococcal CAP was diagnosed based on a serotype-specific pneumococcal antibody response.ResultsS. pneumoniae was serologically identified as causative pathogen in 406/1380 (29%) cases. The five most prevalent serotypes were (in descending order) 11A, 22F, 3, 2 and 19F. Based on the percentage of pneumonia cases associated with PCV10 vaccine types, the potential PCV10 coverage was 29% (116/406).ConclusionsIn almost a third of the studied cases S. pneumoniae was identified as a causative pathogen. Because of the characteristics of the immunoassay, this might well be a gross underestimation. Nevertheless, the potential PCV10-coverage was low. Given the high serotype diversity, the region might benefit greatly from a higher-coverage PCV or recombinant protein vaccine.

Evaluating methods for identifying and quantifying Streptococcus pneumoniae co-colonization using next-generation sequencing data.

Detection of multiple pneumococcal serotype carriage can enhance monitoring of pneumococcal vaccine impact, particularly among high-burden childhood populations. We assessed methods for identifying co-carriage of pneumococcal serotypes from whole-genome sequences. Twenty-four nasopharyngeal samples were collected during community carriage surveillance from healthy children in Blantyre, Malawi, which were then serotyped by microarray. Pneumococcal DNA from culture plate sweeps were sequenced using Illumina MiSeq, and genomic serotyping was carried out using SeroCall and PneumoKITy. Their sensitivity was calculated in reference to the microarray data. Local maxima in the single-nucleotide polymorphism (SNP) density distributions were assessed for their correspondence to the relative abundance of serotypes. Across the 24 individuals, the microarray detected 77 non-unique serotypes, of which 42 occurred at high relative abundance (>10%) (per individual, median, 3; range, 1-6 serotypes). The average sequencing depth was 57X (range: 21X-88X). The sensitivity of SeroCall for identifying high-abundance serotypes was 98% (95% CI, 0.87-1.00), 20% (0.08-0.36) for low abundance (<10%), and 62% (0.50-0.72) overall. PneumoKITy's sensitivity was 86% (0.72-0.95), 20% (0.06-0.32), and 56% (0.42-0.65), respectively. Local maxima in the SNP frequency distribution were highly correlated with the relative abundance of high-abundance serotypes. Six samples were resequenced, and the pooled runs had an average fourfold increase in sequencing depth. This allowed genomic serotyping of two of the previously undetectable seven low-abundance serotypes. Genomic serotyping is highly sensitive for the detection of high-abundance serotypes in samples with co-carriage. Serotype-associated reads may be identified through SNP frequency, and increased read depth can increase sensitivity for low-abundance serotype detection.IMPORTANCEPneumococcal carriage is a prerequisite for invasive pneumococcal disease, which is a leading cause of childhood pneumonia. Multiple carriage of unique pneumococcal serotypes at a single time point is prevalent among high-burden childhood populations. This study assessed the sensitivity of different genomic serotyping methods for identifying pneumococcal serotypes during co-carriage. These methods were evaluated against the current gold standard for co-carriage detection. The results showed that genomic serotyping methods have high sensitivity for detecting high-abundance serotypes in samples with co-carriage, and increasing sequencing depth can increase sensitivity for low-abundance serotypes. These results are important for monitoring vaccine impact, which aims to reduce the prevalence of specific pneumococcal serotypes. By accurately detecting and identifying multiple pneumococcal serotypes in carrier populations, we can better evaluate the effectiveness of vaccination programs.

Genetic diversity and antibiotic resistance patterns of Escherichia coli isolates causing septicemia: A phylogenetic typing and PFGE analysis

IntroductionThis study aims to analyze clinical isolates of E. coli causing septicemia across various phylogroups utilizing the PFGE method. Materials and methodsA total of 100 clinical isolates were collected. The presence of CTX-M, TEM, SHV, KPC, MBL and OXA-48 genes was detected by PCR. Additionally, phylotyping, serotyping, and virulence-typing assay were done by PCR and PFGE methods to investigate the genetic diversity of the isolates. ResultsThe O1 serotype and the HlyA gene were the most prevalent serotype and virulence gene, respectively. Notably, 34% of the isolates harbored SHV, TEM, and CTX-M-1 β-lactamase genes. All isolates showed resistance to amoxicillin and tetracycline, but no resistance to fosfomycin was seen. The most and least common phylotypes, according to PFGE analysis, belonged to phylogroups B2 and B1, respectively. ConclusionThe data offers valuable insights into the genetic diversity and antibiotic resistance patterns of E. coli isolates responsible for septicemia.

Ultrasound analysis of different forms of hemolytic uremic syndrome in children.

Hemolytic uremic syndrome (HUS) is the most common cause of acute kidney injury in children. It is mainly caused by Shiga toxin-producing enterohemorrhagic Escherichia coli (EHEC; STEC-HUS) and is more rarely caused by uncontrolled complement activation (cHUS). Renal replacement therapy is frequently required and kidney function recovers in the majority of patients. Ultrasound (US) is the preferred imaging modality for the evaluation of any renal failure. The aim of this study is the evaluation of US diagnostics in both HUS types at disease onset and in the course of the disease. Clinical, laboratory, and US data from the digital patient records of children admitted as inpatients with a diagnosis of HUS were recruited for a monocentric, retrospective analysis. STEC-HUS and cHUS were diagnosed when, in addition to the laboratory constellation, EHEC infection and complement system activation were verified, respectively. US examinations were performed by pediatricians with certified pediatric US experience. In total, 30 children with STEC-HUS (13/25 male; median age of disease onset 2.9 years; most prevalent EHEC serotype was O157) and cHUS (2/5 male; median age of disease onset 5.4 years; 3/5 with proven pathogenic variation) were included. Renal replacement therapy proportions were comparable in the STEC-HUS and cHUS patients (64% vs. 60%). The resistance index (RI) was elevated at disease onset in the patients with STEC-HUS and cHUS (0.88 ± 0.10 vs. 0.77 ± 0.04, p = 0.13) and was similar in the STEC-HUS subcohorts divided based on dialysis requirement (yes: 0.86 ± 0.1; no: 0.88 ± 0.1; p = 0.74). Total kidney size at disease onset displayed a positive correlation with dialysis duration (R = 0.53, p = 0.02) and was elevated in both HUS types (177% ± 56 and 167% ± 53). It was significantly higher in the STEC-HUS subcohort which required dialysis (200.7% vs. 145%, p < .029), and a regressor kidney size threshold value of 141% was indicated in the receiver operating characteristic analysis. A classification model using both US parameters sequentially might be of clinical use for predicting the need for dialysis in patients with STEC-HUS. The US parameters normalized over time. The US parameters of RI and total kidney size are valuable for the assessment of HUS at disease onset and during therapy, and may be helpful in the assessment of whether dialysis is required in patients with STEC-HUS.

High-Throughput Luminescence-Based Serum Bactericidal Assay Optimization and Characterization to Assess Human Sera Functionality Against Multiple Shigella flexneri Serotypes

Shigellosis represents a significant global health concern particularly affecting children under 5 years in low- and middle-income countries (LMICs) and is associated with stunting and antimicrobial resistance. There is a critical need for an effective vaccine offering broad protection against the different Shigella serotypes. A correlate of protection has not yet been established but there is a general consensus about the relevant role of anti-O-Antigen-specific IgG and its functionality evaluated by the Serum Bactericidal Assay (SBA). This study aims to characterize a high-throughput luminescence-based SBA (L-SBA) against seven widespread Shigella serotypes. The assay was previously developed and characterized for S. sonnei and S. flexneri 1b, 2a, and 3a and has now been refined and extended to an additional five serotypes (S. flexneri 4a, 5b, 6, X, and Y). The characterization of the assay with human sera confirmed the repeatability, intermediate precision, and linearity of the assays; both homologous and heterologous specificity were verified as well; finally, limit of detection and quantification were established for all assays. Moreover, different sources of baby rabbit complement showed to have no impact on L-SBA output. The results obtained confirm the possibility of extending the L-SBA to multiple Shigella serotypes, thus enabling analysis of the functional response induced by natural exposure to Shigella in epidemiological studies and the ability of candidate vaccines to elicit cross-functional antibodies able to kill a broad panel of prevalent Shigella serotypes in a complement-mediated fashion.

Impact of the COVID-19 Pandemic on Pediatric Bacterial Community-Acquired Pneumonia: A Multicenter Retrospective Study in Madrid (Spain).

This study conducted in Madrid (Spain) between 2018 and 2023 shows a significant decrease in the pediatric bacterial community-acquired pneumonia cases during the COVID-19 pandemic, followed by a notable postpandemic increase surpassing prepandemic incidence. Streptococcus pneumoniae remains predominant, with an increasing prevalence of serotype 3, while Streptococcus pyogenes was the second most common pathogen.

Stability assessment of housekeeping genes for qRT-PCR in Yersinia enterocolitica cultured at 22°C and 37°C.

Yersinia enterocolitica, a species within the genus Yersinia, thrives optimally at 22-25°C but can also grow at the mammalian core body temperature of 37°C. This dual temperature adaptability necessitates establishing both temperature conditions in research to examine the effects on various biological processes. In quantitative real-time PCR (qRT-PCR) assays, the selection of appropriate housekeeping genes is vital for data accuracy. Nevertheless, the lack of alternatives and information often leads to the default use of the 16S rRNA gene despite potential limitations. This investigation sourced 16 potential reference genes through a comprehensive review of the literature and transcriptome sequencing data analysis. We validated the expression stability of these genes via qRT-PCR across 12 Y. enterocolitica strains, representing the four prevalent serotypes O:3, O:5,27, O:8, and O:9, isolated from diarrheal patient stool samples. This approach aimed to minimize the impact of serotype heterogeneity. After acquiring Cq values, gene stability was evaluated using four established algorithms-ΔCq, geNorm, NormFinder, and BestKeeper-and subsequently synthesized into a consolidated ranking through the Robust Rank Aggregation (RRA) method. Our study suggests that the genes glnS, nuoB, glmS, gyrB, dnaK, and thrS maintain consistent expression across varying culture temperatures, supporting their candidacy as robust housekeeping genes. We advise against the exclusive use of 16S rRNA for this purpose. Should tradition prevail in its utilization, it must be employed with discernment, preferably alongside one or two of the housekeeping genes identified in this study as internal controls.IMPORTANCEIn our study, we focused on identifying stable reference genes for quantitative real-time PCR (qRT-PCR) experiments on Y. enterocolitica cultured at different temperatures (22°C and 37°C). After thoroughly evaluating 16 candidate genes, we identified six genes-glnS, nuoB, glmS, gyrB, dnaK, and thrS-as exhibiting stable expression across these temperature conditions, making them ideal reference genes for Y. enterocolitica studies. This discovery is crucial for ensuring the accuracy and reliability of qRT-PCR data, as the choice of appropriate reference genes is key to normalizing expression data and minimizing experimental variability. Importantly, our research extended beyond bioinformatics analysis by incorporating validation with clinical strains, bridging the gap between theoretical predictions and practical application. This approach not only underscores the robustness and reliability of our findings but also directly addresses the critical need for experimental validation in the field. By providing a set of validated, stably expressed reference genes, our work offers valuable guidance for designing experiments involving Y. enterocolitica, enhancing the reliability of research outcomes, and advancing our understanding of this significant pathogen.

Effect of pneumococcal conjugate vaccination on pneumococcal carriage in hospitalised children aged 2–59 months in Mongolia: an active pneumonia surveillance programme

Data on changes in pneumococcal serotypes in hospitalised children following the introduction of the pneumococcal conjugate vaccine (PCV) in low-income and middle-income countries are scarce. In 2016, Mongolia introduced the 13-valent PCV (PCV13) into the national immunisation programme. We aimed to describe the trend and impact of PCV13 introduction on pneumococcal carriage in hospitalised children aged 2-59months with pneumonia in Mongolia over a 6-year period. In this active surveillance programme, children aged 2-59months with pneumonia who met the study case definition (cough or difficulty breathing with either respiratory rate ≥50beats per min, oxygen saturation <90%, or clinical diagnosis of severe pneumonia) were enrolled between April 1, 2015, and June 30, 2021, from four districts in Ulaanbaatar. We tested nasopharyngeal samples collected at enrolment for pneumococci using lytA real-time quantitative PCR and conducted molecular serotyping and detection of antimicrobial resistance (AMR) genes with DNA microarray. We used log-binomial regression to estimate prevalence ratios (PRs) of pneumococcal carriage, comparing prevalence in the periods before and after the introduction of PCV13 and between vaccinated and unvaccinated children for three outcomes: overall, PCV13 vaccine-type, and non-PCV13 vaccine-type carriage. PRswere adjusted with covariates that were identified by use of a directed acyclic graph, informed by relevant literature. A total of 17 688 children were enrolled, of whom 17 607 (99·5%) met the study case criteria. 6545 (42·5%) of 15 411collected nasopharyngeal swabs were tested for pneumococci. In all age groups, a similar prevalence of pneumococcal carriage was shown between the pre-PCV13 period and post-PCV13 period (882 [48·0%] of 1837 vs 2174[46·2%] of 4708; adjusted PR 0·98 [95% CI 0·92-1·04]; p=0·60). Overall, vaccine-type carriage reduced by43·6% after the introduction of PCV13 (adjusted PR 0·56 [95% CI 0·51-0·62]; p<0·0001). Younger children (aged 2-23months) showed a 47·7% reduction in vaccine-type carriage (95% CI 41·2-53·5; adjusted PR 0·52 [95% CI 0·46-0·59]; p<0·0001), whereas children aged 24-59months had a 29·3% reduction (12·6-42·8; 0·71[0·57-0·87]; p=0·0014). Prevalence of 6A, 6B, 14, 19F, and 23F decreased following the introduction of PCV13; however, 19F and 6A remained common (5·8% and 2·9%). Non-vaccine-type carriage increased (adjusted PR 1·49[95% CI 1·32-1·67]), with 15A, NT2, and 15B/C being the most prevalent serotypes. Overall, 1761 (89·3%) of 1978analysed samples contained at least one AMR gene. The percentage of samples with any AMR gene decreased with vaccine introduction (92·3% in the pre-PCV13 period vs 85·3% in the post-PCV13 period; adjusted odds ratio 0·49 [95% CI 0·34-0·70]), with similar decreases for samples with at least three AMR genes (46·8% vs 27·6%; 0·44 [0·36-0·55]). 6 years after the introduction of PCV13 in Mongolia, the prevalence of vaccine-type carriage and AMR genes showed a reduction among young hospitalised children with pneumonia. Reductions in vaccine-type carriage are likely to result in reductions in pneumococcal pneumonia. GAVI, the Vaccine Alliance.

Serotype distribution and antimicrobial resistance of Streptococcus pneumoniae isolated from children in Japan, 2023

BackgroundThe prevalence of serotypes and antimicrobial resistance of Streptococcus pneumoniae was characterized among children thirteen years after the licensure of the pneumococcal conjugate vaccine (PCV) in Japan. MethodsA total of 353 pneumococcal isolates were collected from Japanese children between March and July 2023. All the isolates were serotyped using genetic methods and tested for susceptibility to 14 antimicrobial agents. ResultsAmong the 353 isolates, the prevalence rates of non-PCV13 and non-PCV20 serotypes were 96.9 % and 77.9 %, respectively, including the dominant non-PCV13/PCV20 serotypes 23A (16.1 %), 35B (15.3 %), 15A (10.5 %), 15C (9.3 %), and 34 (9.1 %), which accounted for 60.3 % of all isolates. The high non-susceptibility rates were observed for macrolides (erythromycin, azithromycin, and clarithromycin; ≥81.9 %) and tetracycline (80.7 %). Penicillin non-susceptibility and multidrug resistance (MDR) were detected in 49.9 % (6.8 % resistant and 43.1 % intermediate) and 68.3 % of the isolates, respectively. The three most common non-PCV13/PCV20 serotypes 15A, 23A, and 35B exhibited high prevalence rates of penicillin non-susceptibility (≥89.5 %) and MDR (≥81.5 %). Extensive drug resistance was observed in 10.5 % of all isolates belonging to six different serotypes (12F, 23A, 11A, 15A, 35B, and 15B) and in the non-encapsulated strains of S. pneumoniae. ConclusionsOur study revealed a higher prevalence of non-susceptibility to penicillin with MDR in the three most common non-PCV13/PCV20 serotypes 15A, 23A, and 35B, in Japan, suggesting their persistence in the PCV13 era.

Prevalence, antimicrobial resistance, and genomic characterization of Salmonella strains isolated in Hangzhou, China: a two-year study.

This study explored the molecular epidemiology and resistance mechanisms of 271 non-duplicate Salmonella enterica (S. enterica) strains, isolated mainly from adults (209/271) in a tertiary hospital in Hangzhou between 2020 and 2021. Through whole-genome sequencing and bioinformatics, the bacterial strains were classified into 46 serotypes and 54 sequence types (ST), with S. Enteritidis, S. 1,4,[5],12:i:-, and S. Typhimurium being the most prevalent serotypes and ST11, ST34, and ST19 the most common STs. The strains isolated from adults were primarily S. Enteritidis (59/209), while from children were mainly S. 1,4,[5],12:i:- (20/62). Worryingly, 12.55% strains were multi-drug resistant (MDR), with resistance rates to cefepime (FEP), ceftazidime (CAZ), ceftriaxone (CRO) and cefotaxime (CTX) of 7.38%, 9.23%, 15.87% and 16.24%, respectively, and resistance rates to levofloxacin (LEV) and ciprofloxacin (CIP) of 8.49% and 19.19%, respectively. It is worth noting that the resistance rates of CRO and CTX in children reached 30.65%. A total of 34 strains carried extended-spectrum β-lactamase (ESBL) genes, dominated by blaCTX-M-65 (13/34) and blaCTX-M-55 (12/34); it is notable that one strain of S. Saintpaul carried both blaCTX-M-27 and blaCTX-M-55. The resistance mechanism to cephalosporins was mainly due to ESBL genes (20/43), and other genes included AmpC and β-lactamase genes. The strains resistant to quinolones mainly carried qnrS1 (27/53), and others included qnrB6, aac(6')-Ib-cr, and mutations in gyrA and parC. One strain did not carry common quinolone resistance genes but had a parC (p.T57S) mutation to cause CIP resistance. This research provides vital insights into the molecular epidemiology and resistance mechanisms of clinical S. enterica, implicating possible infection control strategies.

Prevalence and characteristics of ESBL-producing Salmonella in Weifang, China.

This study examined the prevalence and antibiotic resistance pattern of blaCTX-M extended-spectrum β-lactamase positive Salmonella species isolated from a hospital in Weifang. Salmonella strains were isolated from hospitalized patients from January 2018 to April 2023. Whole-genome sequencing was performed by Illumina platform. CTX-M-producing Salmonella were identified by Comprehensive Antibiotic Research Database (CARD). Strain susceptibility to six antimicrobial agents was assessed by BD Phoenix™ M50 System. MLST analysis confirmed sequence types and additionally, serotypes were determined by SeqSero2. Genetic environments of blaCTX-M genes were analyzed by Isfinder and BLASTn. Single nucleotide polymorphisms were used to construct a phylogenetic tree to analyze homology.A total of 34 CTX-M-producing Salmonella were detected. The most prevalent serotype was Salmonella enterica subsp. enterica 1,4,[5],12:i:- (14/34, 41.18%), belonging to ST34, followed by SalmonellaEnteritidis (10/34, 29.41%), belonging to ST11. The highest resistance rate was detected to ampicillin (97.06%), followed by ceftriaxone (94.12%) and ceftazidime (58.83%). In CTX-M-producing Salmonella five types of blaCTX-M genes were identified, the most prevalent was blaCTX-M-55 (47.06%, 16/34), followed by blaCTX-M-14, blaCTX-M-65, blaCTX-M-125, and blaCTX-M-27 at 26.47% (9/34), 11.77% (4/34), 8.82% (3/34), and 5.88% (2/34), respectively. Apart from blaCTX-M, 40 antibiotic resistance genes were also detected, conveying resistance to multiple drugs and the most frequent genes were namely, mcr-1.1, aph(6)-Id, aph(3″)-Ib, oqxAB, qnrB6, qnrS1. According to genetic environment analysis, the insertion sequence ISEcp1 was prevalent upstream of the blaCTX-M gene. Our study demonstrates that multiple resistance genes are carried by clinical isolates of Salmonella spp. however, the dominant ESBL genotype is CTX-M-55, that is associated with ISEcp1.

Pneumolysin-responsive liposomal platform for selective treatment of Streptococcus pneumoniae.

The bacterium Streptococcus pneumoniae has become a leading cause of meningitis, sepsis, and bacterial pneumonia worldwide, with increased prevalence of antibiotic-resistant serotypes serving to exacerbate the issue. The main factor responsible for colonization and immune response escape in pneumococcal infections is the secreted molecule pneumolysin, which is a subset within a family of related toxins that form transmembrane pores in biological membranes through cholesterol recognition and binding. The conserved activity and structure of pneumolysin between all observed S. pneumoniae serotypes, along with its requirement for pathogenicity, has made this molecule an attractive target for vaccination, diagnostic, and sequestration platforms, but not yet as a facilitative agent for therapeutic treatment. Consequently, the present work aimed to examine the impact of liposomal cholesterol content for pneumolysin-induced release of the encapsulated antimicrobial peptide nisin. It was determined that a cholesterol content above 45mol% was necessary to facilitate interactions with both purified pneumolysin toxin and S. pneumoniae culture, demonstrated through enhanced nisin release and a reduction in hemolytic rates upon exposure of the toxin with cholesterol-rich vesicles. Antibacterial testing highlighted the ability of the developed platform to elicit a potent and specific bactericidal response in vitro against cultured S. pneumoniae when compared to a control strain, Staphylococcus epidermidis. It further improved viability of a fibroblast cell line upon S. pneumoniae challenge, outperforming free nisin via the synergistic impact of simultaneous bacterial clearance and pneumolysin neutralization. These findings collectively indicate that cholesterol-rich liposomes hold promise as a selective treatment platform against pneumococcal infections.

Epidemiology of Human Parainfluenza Virus Infections among Pediatric Patients in Hainan Island, China, 2021-2023.

Human parainfluenza viruses (HPIVs) are the leading causes of acute respiratory tract infections (ARTIs), particularly in children. During the COVID-19 pandemic, non-pharmaceutical interventions (NPIs) significantly influenced the epidemiology of respiratory viruses. This study analyzed 19,339 respiratory specimens from pediatric patients with ARTIs to detect HPIVs using PCR or tNGS, focusing on the period from 2021 to 2023. HPIVs were identified in 1395 patients (7.21%, 1395/19,339), with annual detection rates of 6.86% (303/4419) in 2021, 6.38% (331/5188) in 2022, and 7.82% (761/9732) in 2023. Notably, both the total number of tests and HPIV-positive cases increased in 2023 compared to 2021 and 2022. Seasonal analysis revealed a shift in HPIV prevalence from winter and spring in 2021-2022 to spring and summer in 2023. Most HPIV-positive cases were in children aged 0-7 years, with fewer infections among those aged 7-18 years. Since June 2022, HPIV-3 has been the most prevalent serotype (59.55%, 524/880), whereas HPIV-2 had the lowest proportion (0.80%, 7/880). The proportions of HPIV-1 (24.89%, 219/880) and HPIV-4 (15.45%, 136/880) were similar. Additionally, the incidence of co-infections with other common respiratory pathogens has increased since 2021. This study highlights rising HPIV detection rates post-COVID-19 and underscores the need for continuous surveillance of HPIVs to inform public health strategies for future epidemic seasons.

Streptococcus pneumoniae carriage, serotypes, genotypes, and antimicrobial resistance trends among children in Portugal, after introduction of PCV13 in National Immunization Program: A cross-sectional study

Streptococcus pneumoniae carriage studies are crucial to monitor changes induced by use of pneumococcal conjugate vaccines and inform vaccination policies. In this cross-sectional study, we examined changes within the pneumococcal population following introduction of PCV13 in 2015 in the National Immunization Program (NIP), in Portugal. In 2018–2020 (NIP-PCV13), we obtained 1450 nasopharyngeal samples from children ≤6 years attending day-care. We assessed serotypes, antimicrobial resistance, and genotypes (MLST and GPSC) and compared findings with earlier periods: 2009–2010 (pre-PCV13), 2011–2012 (early-PCV13), and 2015–2016 (late-PCV13). Pneumococcal carriage prevalence remained stable at 60.2 %. Carriage of PCV13 serotypes was 10.7 %, markedly reduced compared to pre-PCV13 period (47.6 %). The most prevalent PCV13 serotypes were 19F, 3, and 19A all showing a significant decreasing trend compared to the pre-PCV13 period (from 7.1 % to 4.7 %, 10.1 % to 1.8 %, and 14.1 % to 1.8 %, respectively), a notable observation given the described limited effectiveness of PCV13 against serotype 3. Non-vaccinated children and children aged 4–6 years were more likely to carry PCV13 serotypes (2.5-fold, 95 %CI [1.1–5.6], and 2.9-fold, 95 %CI [1.3–6.8], respectively). The most prevalent non-PCV13 serotypes were 15B/C, 11A, 23B, 23A, and NT, collectively accounting for 51.9 % of all isolates. In total, 30.5 % of all pneumococci were potentially covered by PCV20. Resistance to penicillin (low-level) and macrolides increased significantly, from 9.3 % and 13.4 %, respectively, in the late-PCV13 period, to approximately 20 % each, mostly due to lineages expressing non-PCV13 serotypes, nearing pre-PCV13 levels. An expansion of lineages traditionally associated with PCV13 serotypes, like CC156-GPSC6 (serotype 14) and CC193-GPSC11 (serotype 19F), but now predominantly expressing non-PCV13 serotypes (11A, 15B/C, and 24F for GPSC6; and 15A and 21 for GPSC11) was noted. These findings indicate that the pneumococcal population is adapting to the pressures conferred by PCV13 and antimicrobial use and indicate the need to maintain close surveillance.

Role of IgM/ IgG Ratio in Distinguishing Primary and Secondary Dengue Viral Infections: A Cross-Sectional Study.

Objectives In recent years, Uttarakhand, a state in North India has become one of the prime spots for tourism all over the world. Thereby, a tremendous increase in the epidemics of dengue infection has been observed recently. Secondary dengue causes more severe disease in comparison with primary, thus to differentiate the two is very crucial. We aim to find out the cut-off values of the IgM:IgG ratio for early detection of secondary dengue which could further help clinicians to prevent the complications. Methods A cross-sectional study was conducted over one year involving around 936 suspected cases of dengue. Samples were tested using the commercially available capture enzyme linked Immunosorbent assay (ELISA) method for IgM and IgG. Real-time and nested polymerase chain reaction (PCR) tests were also done to find out the prevalent serotype. IgM:IgG ratio was evaluated by using receiver operating characteristic curve analysis for the differentiation of primary and secondary dengue. Results Among the total 91 serologically confirmed dengue patients, forty-seven (51.6%) were found to be primary, and forty-four (48.4%) were secondary dengue infections with male preponderance. Using the WHO diagnostic criteria, patients with dengue fever (DF) without warning signs added up to 51.6%, with warning signs 42.9% and severe dengue 5.5% of the total cases. The cut-off ratio of IgM:IgG ratio = 1.59 found the best discrimination between primary and secondary infection. Forty out of ninety-one (44%) patients exhibited ratios of > 1.59 whereas the rest fifty-one (56%) exhibited ratios of < 1.59. Dengue virus - 2 (DENV- 2) was found to be the most prevalent serotype. Conclusion Our study recommends the cut-off values for IgM:IgG ratio as 1.59. Therefore it is hoped that this will guide the clinicians to early distinguish between primary and secondary dengue. Furthermore, it can reduce morbidity and mortality because of dengue infections in the future.

Pathogenic Leptospira interrogans in Jos North Abattoir, Nigeria: Occurrence, serology, and molecular characterization

Leptospirosis, a neglected zoonotic disease, adversely affects animal, human health, and socioeconomic conditions, particularly in developing countries like Nigeria. This study aimed to determine the occurrence and molecular identification of pathogenic Leptospira spp. among abattoir workers, cattle, and rats in Jos North, Plateau State, Nigeria. Using a cross-sectional study design, a total of 394 samples were collected, including 149 urine samples from abattoir workers, 125 urine samples from cattle bladders, and 120 bladders from trapped rats. Samples were processed and cultured in Ellinghausen McCullough Johnson Harrison (EMJH) medium and examined under a darkfield microscope. Positive cultures were confirmed using the Microscopic Agglutination Test (MAT) and nested Polymerase Chain Reaction (N-PCR) targeted the 16 S rDNA gene. Results revealed a prevalence of 33.76 % for Leptospira spp. across all samples, with the highest occurrence in abattoir workers (13.96 %), followed by rats (13.45 %), and cattle (6.35 %). The MAT showed L. interrogans serovar Hardjo str. Hardjoprajitno as the most prevalent serotype (41.61 %), followed by L. interrogans serovar Icterohaemorrhagiae str. RGA (34.31 %). N-PCR confirmed the presence of pathogenic Leptospira spp., showing bands of 1200 bp. Phylogenetic analysis of the 16 S rDNA gene sequences revealed close similarities to known pathogenic Leptospira strains from Brazil and the USA. The study underscores the significant public health risk posed by leptospirosis in Jos North and highlights the need for improved diagnostic capabilities, increased awareness, and effective control measures to mitigate the disease burden. Enhanced surveillance and preventive strategies are crucial to protect both animal and human health in the region.

Temporal and Serotypic Dynamics of Actinobacillus pleuropneumoniae in South African Porcine Populations: A Retrospective Study from 1985 to 2023.

Actinobacillus pleuropneumoniae is a major bacterial pathogen causing porcine pleuropneumoniae, which is a disease of notable economic impact and high fatality rates among pigs worldwide. It has been reported that 19 distinct serotypes of this bacterium exist. Despite its global prominence, there exists a scarcity of information regarding its prevalence and distribution in South Africa. Thus, this study used laboratory records to investigate the serotype diversity, temporal distribution, and seasonal patterns of A. pleuropneumoniae isolated from porcine samples spanning from 1985 to 2023 within South Africa. Data from laboratory registries of 354 cases, obtained from three veterinary laboratories in South Africa, were analyzed. The data were categorized into two-time frames: term 1, covering 1985 to 2001, and term 2, spanning from 2002 to 2023. The dataset identified 11 different serotypes, with serotype 7 being the most prevalent at 22.7% (n = 62), which was followed by serotype 5 at 13.8% (n = 42). The study highlighted variations in the prevalence of serotypes among diseased animals over a 38-year period. Serotypes 3, 5, 7 and 8 were commonly observed during this time, while serotype 4 was absent from 1985 to 2001, and serotypes 1, 6, and 10 were absent from 2002 to 2023. The distribution of serotypes showed a diverse variation in the age of affected animals, clinical manifestation, and seasonal occurrence. Key findings revealed that serotype 7 was the most prevalent across all seasons with the highest occurrence in winter. Additionally, Gauteng province showed the highest prevalence of various serotypes. The information collected during this study will serve as a baseline for future epidemiological studies as well as inform control strategies.