Search Results (416)

Background: Cholera, caused by Vibrio cholerae, remains endemic in many developing countries, including Pakistan. The extensive use of antibiotics has led to the emergence of antimicrobial resistance in V. cholerae, limiting available treatment options. In this study, we performed molecular characterisation of antibiotic-resistant V. cholerae serotype Ogawa isolates from a recent cholera outbreak in Khyber Pakhtunkhwa, Pakistan. Methodology: Suspected cholera stool samples were collected from hospitalised patients at various district hospitals of Khyber Pakhtunkhwa Province (KPK), Pakistan. The samples were transported to the Public Health Reference Microbiology Laboratory at Khyber Medical University, Peshawar. V. cholerae were identified based on colonial morphology, Gram staining, and biochemical tests using EPI 10E. For serotype identification, monovalent antisera were used. Antibiotic susceptibility testing (AST) was performed using CLSI M45 and EUCAST guidelines. DNA was extracted from pure colonies of multidrug-resistant (MDR) V. cholerae and subjected to whole-genome sequencing (WGS) for genomic characterisation using an Illumina MiSeq platform. Results: Of the 350 active diarrheal cases investigated, 70 were confirmed as V. cholerae. The outbreak was initially reported in Dir and was subsequently followed by a high incidence of cholera in the Peshawar district of KPK. All strains belong to the Ogawa serotype, which shows high antibiotic resistance, particularly to ampicillin (n = 62, 88.57%), Sulfamethoxazole/Trimethoprim (n = 60, 85.71%), Erythromycin (n = 59, 84.29%), and Tetracycline (n = 53, 75.71%). The lowest resistance was against Meropenem (n = 1, 1.4%), followed by amikacin (n = 7, 10.0%) and levofloxacin (n = 13, 18.57%). Furthermore, 34 (48.57%) of the isolates were MDR, while 13 (18.57%) were extensively drug-resistant. Six samples were selected for whole-genome sequencing. The selection of six V. cholerae samples for WGS was based on their drug resistance pattern and origin of isolation. At the genomic level, all sequenced V. cholerae strains harboured multiple antimicrobial resistance determinants. Quinolone resistance was associated with mutations and genes in gyrA, gyrB, parC, and parE; resistance to sulfamethoxazole–trimethoprim with folA, folP, and dfr; tetracycline resistance with tetA and tet35; chloramphenicol resistance with catB and S10p; and aminoglycoside resistance with hns, S12p, and gigB. In addition, β-lactam resistance was linked to the presence of efflux and β-lactamase genes, including blaSHV and mox-3. Mutations were identified in gyrA at positions S83I, S177A, and S202A, and in parC at positions S85L and I231V. Collectively, the presence of these resistance determinants likely enables V. cholerae to survive exposure to high concentrations of multiple antibiotics. Conclusions: Our V. cholerae isolates showed close genetic relatedness to previously sequenced strains from Pakistan (2010 and 2022), as well as to recently reported international strains from the USA, Australia, and China. These findings highlight both the long-term persistence of these lineages within Pakistan and their international dissemination, likely facilitated by globalisation. Full article

(1) Background: As an innovative drug derived from botulinum neurotoxin serotype E, TrenibotulinumtoxinE^® demonstrates a rapid onset and shorter effect. Due to concerns regarding specificity, test throughput, and animal welfare, a new cell-based potency assay (CBPA) method was developed for BoNT/E drug substance and drug product; independent evaluation of this new CBPA was required. (2) Methods: The CBPA for BoNT/E is a quantitative assay that measures the accumulated cleaved SNAP25₁₈₀ in human neuroblastoma cells. It involves sequential culturing, differentiation of cells, and then treatment with drug products. Data were analyzed using a quadratic parallel model via statistical software. Linearity was determined using five effective concentration levels. Key assay parameters including accuracy, linearity, repeatability, intermediate precision and range were evaluated. (3) Results: The overall assay’s accuracy was 98%, and the intermediate precision was 6.3%. The coefficient of determination (R²) and slope were determined as 0.963 and 0.942, respectively. The root mean squared error (RMSE) was 0.057, and the intercept was 0.032 for the combined data. The repeatability was 2.4%, which is well within the acceptance criterion of ≤8%. (4) Conclusions: The evaluation was carried out within a single laboratory under controlled conditions; the new CBPA meets all acceptance criteria and can be used for BoNT/E potency determination. Full article

Bacterial resistance in foodborne pathogens is a global concern and has stimulated the search for alternative compounds to antimicrobials. In this context, the prevention of colonization by Salmonella spp. in poultry production is particularly important. This study investigated the bactericidal effect of lysozyme on Salmonella Heidelberg and Salmonella Minnesota. A total of 44 serotyped isolates were subjected to minimum inhibitory concentration (MIC) testing against 17 distinct antibiotics. Subsequently, the same isolates were subjected to minimal bactericidal concentration (MBC) with lysozyme at concentrations ranging from 15 to 2000 ppm. One strain of S. Heidelberg was selected for an in vivo challenge. Seventy-two male chicks were randomly divided into three experimental groups, and two of them were challenged on the second day with 0.5 mL of an inoculum containing 1 × 10⁵ CFU/mL. One of these groups was treated with lysozyme at a concentration of 1000 ppm per bird for 21 days. MIC tests showed that the multidrug resistance rate was 97.72%, with susceptibility only to fosfomycin, florfenicol, and meropenem. After the in vitro exposure of these isolates to lysozyme, 86.36% were inhibited at concentrations ≤ 15 ppm. The in vivo tests showed a significant reduction in the total number of chickens colonized by S. Heidelberg at 2, 5, 7, 14, 18, and 21 days of farming. On the day of slaughter, the percentage of positive birds in the inoculated group was 63.63%, while that in the group treated with lysozyme was 26.08%. These data highlight the potential use of lysozyme as an alternative to antibiotics in poultry production. Full article

Background: Being central players in the adaptive immunity, the study of T-cell responses is crucial in both natural infections and vaccine-induced immunity. In this study, we assessed the antigen-specific T-cell responses to dengue virus (DENV) to identify the most immunogenic antigen for evaluating dengue-specific T-cell responses. Methods: Patients with dengue disease and subjects vaccinated with the QDENGA (TAK-003) vaccine (before and three months after vaccination) were enrolled. The T-cell-specific response was measured by ELISPOT and Activation Induced Markers (AIM) assay following PBMC stimulation either with DENV1-4 CD4 and CD8 MegaPools (MP) or serotype-specific DENV peptide pools at different concentrations. Results: We found that both DENV1-4 CD4 MP (at 1 µg/mL) and CD8 MP (at 5 µg/mL), which encompass all four DENV serotypes, elicited specific T-cell responses in patients with dengue infection independent of the infecting serotype. In contrast, selected serotype-specific DENV peptide pools have a lower ability to induce a measurable T-cell response. Moreover, DENV1-4 CD4 and CD8 MPs, at the highest concentrations, are suitable candidates to evaluate the dengue-specific T-cell response in vaccinated subjects. Conclusions: These findings support the use of the MP approach to investigate dengue-specific T-cell response to monitor the response during the infection and after vaccine administration. Full article

Background: Acute otitis media (AOM) is one of the most common pediatric infections. We aimed to investigate the bacterial profile of AOM in children, the serotype distribution, and the main genetic virulence factors involved in adhesion, immune evasion, and tissue spread. Methods: In total, 121 AOM cases involving children aged 0 to 14 years were studied. Middle ear fluids (MEF) (n = 42) and nasopharyngeal samples (n = 79) were collected. All strains were identified using routine microbiological tests, conventional PCRs and real-time PCR methods. Molecular serotyping was performed for S. pneumoniae and H. influenzae isolates. An immunofluorescence serotyping technique was employed for M. catarrhalis. Target genetic factors were determined for all involved bacterial agents using singleplex or multiplex PCRs. Results: We analyzed 148 nasopharyngeal and MEF. Among 121 AOM cases, a total of 127 bacterial agents were identified, including S. aureus (n = 41), S. pneumoniae (n = 28), H. influenzae (n = 23), M. catarrhalis (n = 19), and S. pyogenes (n = 16). The leading three serotypes among S. pneumoniae were: 19A (18.0%), 6A (14.3%), and 15B (14.3%). 91.3% of H. influenzae isolates were non-typeable (lacking a capsule—NTHi). The M. catarrhalis isolates were distributed in serotypes A (57.9%), B (26.3%), and C (15.8%). Presence of pili type 1 was detected in 21.4% pneumococci, and the fimbrial gene hifA was found in 34.8% of the H. influenzae strains. In 73.6% of the M. catarrhalis strains, ompCD was identified, while 84.2% contained ompE. 62.5% of the S. pyogenes isolates harbored the sdc gene, and 56.2% possessed the sdaD gene, predominantly in the MEF isolates. The cna adhesin was found in 28.0% of the S. aureus strains. Conclusions: The monitoring of bacterial pathogens responsible for otitis media, along with their serotype distribution and the prevalence of genetic factors involved in disease pathogenesis, is essential for public health and can help predict disease severity and treatment options. Full article

Background: Antimicrobial resistance (AMR) has been predicted to worsen with rising ambient temperatures and climate change, though the causal association between temperature and antimicrobial resistance in Salmonella species remains unconfirmed. This study investigates the association between rising ambient temperatures and resistance to antimicrobials used to treat Salmonella bacteraemia in Queensland, Australia. Methods: Time-series analysis with distributed lag non-linear models was used to test associations between deseasonalised temperature and resistance to ampicillin, ciprofloxacin, gentamicin, and third-generation cephalosporins, adjusting for precipitation, seasonality, and temporal trends. Results: A total of 1012 Salmonella bacteraemia cases were analysed in this study. Resistance to any antibiotic occurred in 25.5% of cases (95% CI: 22.8–28.3), resistance to gentamicin in 15.4% (95% CI: 13.2–17.8), and resistance to cephalosporins in 15% (95% CI: 12.9–17.4), with variation among Salmonella serotypes. After adjustment, no antimicrobial resistance was significantly associated with temperature: gentamicin (RR = 1.23 per 1 °C, 95% CI: 0.57–2.65, p = 0.59), cephalosporins (RR = 1.19, 95% CI: 0.52–2.72, p = 0.68), ciprofloxacin (RR = 1.88, 95% CI: 0.29–12.03, p = 0.50), and ampicillin (RR = 1.93, 95% CI: 0.28–13.17, p = 0.50). A marginal temperature–precipitation interaction for cephalosporins, identified using GAM (p = 0.048), did not remain significant after multiple testing correction, nor was it robust across model specifications (GLM p = 0.058) or cross-validation. Conclusions: The findings demonstrate that climate–AMR relationships are not universal, highlighting the importance of geographic, epidemiologic, and organism contexts in these associations. Full article

African horse sickness (AHS) is a lethal vector-borne disease caused by African horse sickness virus (AHSV) and represents a major threat to equine health and the horse industry. In 2020, outbreaks of AHS caused by AHSV serotype 1 (AHSV-1) were reported in Thailand, increasing the risk of AHS introduction into China. Given the safety issues associated with currently available live attenuated AHS vaccines, the development of safer and more effective vaccination strategies is urgently needed. In this study, we constructed a recombinant fowlpox virus (rFPV) expressing the AHSV-1 VP2 protein as a candidate vaccine, designated rFPV-VP2. The recombinant virus was verified by PCR and Western blot analysis, which confirmed the successful expression of VP2. Preliminary immunization trials were conducted in both mice and horses, and immune responses were evaluated via an indirect enzyme-linked immunosorbent assay (iELISA) and immunofluorescence assay (IFA). The results revealed that VP2-specific antibodies were successfully induced in the serum of rFPV-VP2-immunized animals. Notably, serum from immunized horses showed specific reactivity with AHSV-1, confirming the induction of AHSV-1-specific immune responses. Therefore, these results demonstrate that rFPV-VP2 is a promising candidate vaccine for AHSV-1 and provide a scientific basis for the development of safer preventive strategies. Full article

The four serotypes of dengue virus (DENV), types 1 to 4 (DENV-1 to DENV-4), exhibit approximately 60% identity in the encoded amino acid residues of viral proteins. Reverse transcription of RNA extracted from patient serum specimens followed by PCR amplification with serotype-specific probes is the current standard technique for DENV serotyping. However, this method is time- and cost-consuming, and rapid detection systems with low cost are desirable. Previously, we developed a prototype serotype-specific immunochromatography system. That system was composed of four strips with four corresponding distinct sample buffers, each specifically detecting a single DENV serotype. In the present study, we improved this system by combining pairs of strips into one lateral-flow cassette each, providing DENV-1 and DENV-2 detection in one device and DENV-3 and DENV-4 detection in a second device; this strategy successfully reduced the required sample volume. Furthermore, we were able to adjust the composition of the sample buffers such that a single sample buffer sufficed for all four DENV serotype detection reactions, allowing much easier handling of the devices. Evaluation of this new device against laboratory and clinical DENV isolates and clinical specimens from DENV-infected individuals showed sensitivity that was comparable to that of our previous version, yielding serotype specificity of 100%. These new devices are expected to be of use in the clinical setting, accelerating both prospective and retrospective epidemiological studies. Full article

Dengue fever has become a major global public health challenge due to its rapidly in-creasing incidence. Rapid on-site detection of dengue virus (DENV) is critical for early diagnosis, timely patient isolation, and outbreak control. In this study, dengue virus serotype 2 (DENV-2), the predominant strain circulating in tropical and subtropical regions, was selected as the target pathogen. We established a one-tube rapid detection assay that integrates the HUDSON nucleic acid extraction-free protocol, reverse transcription recombinase-aided amplification (RT-RAA), and CRISPR/Cas12a-mediated trans cleavage activity. The method achieved a detection limit of 1 × 10² copies/μL for simulated infected samples and exhibited no cross-reactivity with other DENV serotypes (DENV-1, DENV-3, DENV-4) or with other arboviruses, including Zika, Japanese encephalitis, yellow fever, and chikungunya viruses. The assay demonstrated high sensitivity and specificity across various sample types, including mosquitoes, rodents, blood, and cultured cells, with results consistent with quantitative PCR (qPCR). Requiring only basic equipment such as a water bath, the system enables on-site detection of DENV-2 within 1 h. This simple, cost-effective, and reliable assay provides a practical tool for field-based DENV-2 surveillance and supports effective public health responses in resource-limited settings. Full article

Foot-and-mouth disease (FMD), a vesicular disease, causes lesions in the mouth, nose, teats, and feet of cloven-hoofed animals. Vaccination remains the most effective method to prevent FMD outbreaks. Since 2010, South Korea has implemented nationwide vaccination and developed multiple domestic vaccine strains to achieve vaccine self-sufficiency. Here, we aimed to construct an infectious clone using the A/SKR/Yeoncheon/2017 virus, which exhibits the highest antigen productivity among previously developed vaccine strains. An infectious clone was constructed based on the A/Yeoncheon/SKR/2017 virus isolated during an FMD outbreak in Korea in 2017. The viral genome was amplified in two fragments and assembled into a full-length clone, from which infectious recombinant virus was successfully rescued. The rescued virus was confirmed via serotyping and transmission electron microscopy to exhibit canonical 25–30 nm icosahedral morphology. Under optimized culture conditions using suspension-adapted BHK-21 cells (multiplicity of infection 0.001; 12 h post-infection), the recombinant virus achieved titers of 10⁸ TCID₅₀/mL and produced 6.2 μg/mL of 146S antigen, comparable to its parental counterpart. The experimental vaccine formulated with the rescued virus (15 μg/dose), 1% saponin, 1% aluminum hydroxide gel, and ISA 206 VG, induced protective immunity in eight-week-old pigs, with vaccinated animals exhibiting no clinical signs following homologous challenge. To our knowledge, this study represents the first successful construction of an infectious clone derived from a field-isolated serotype A FMDV in South Korea. In the future, this A/SKR/Yeoncheon/2017 infectious clone can serve as a platform backbone for the rapid development of next-generation, high-yield vaccine seed strains through targeted epitope exchange. Full article

(1) Background: Salmonella are zoonotic pathogens, and rising antimicrobial resistance (AMR) amplifies their public health impact. Asymptomatic horses can act as reservoirs, contributing to environmental contamination and interspecies transmission. This study aimed to estimate the prevalence of Salmonella and characterize AMR patterns in healthy horses from eastern Spain. (2) Methods: Faecal samples from 95 asymptomatic horses were collected once daily over five consecutive days (475 samples in total) and processed under for Salmonella detection. Epidemiological information was obtained through owner questionnaires, and associations with Salmonella shedding were analyzed using generalized linear models. Antimicrobial susceptibility was assessed by minimum inhibitory concentration assays following the European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria. (3) Results:Salmonella was detected in 25.3% of horses (24/95), with S. Enteritidis, S. Johannesburg, and S. Virchow as the most frequent serotypes. A significant association was observed between proximity of manure storage and bacterial detection (p < 0.001). Among 24 isolates of Salmonella, 88.9% were resistant to at least one antimicrobial, and 50% exhibited multidrug resistance. The highest resistance rates were against sulfamethoxazole and gentamicin, followed by ciprofloxacin and tigecycline. (4) Conclusions: Healthy horses can act as silent carriers of multidrug-resistant Salmonella, highlighting the need for surveillance, strengthened biosecurity, and prudent antimicrobial use within a One Health framework. Full article

Objectives: This study systematically assessed the safety and immunogenicity of a new 13-valent pneumococcal conjugate vaccine (CRM197/TT, PCV13i) against the licensed PCV13 vaccine in a cohort of Chinese children between 12 and 23 months of age. Methods: This is a phase III, randomized, double-blind trial (NCT04841369). A total of 528 participants were randomized 1:1 to receive two doses of either PCV13i experimental or the PCV13 control vaccine at a 2-month interval, with 517 participants completing the vaccinations. Results: The overall incidence of adverse events (37.12% vs. 32.70%, p = 0.134) and adverse reactions (24.81% vs. 21.61%, p = 0.221) was comparable between the experimental and control groups. Local adverse reactions were more frequent in the experimental group (10.00% vs. 6.12%, p = 0.021), such as erythema (7.88% vs. 4.02%, p = 0.008). Systemic adverse reactions, including fever (10.77% vs. 13.77%), showed no significant differences. No vaccine-related serious adverse events occurred. Immunogenicity assessments showed that seropositivity rates for most serotypes reached ≥96% in both groups, with eight serotypes achieving 100% seropositivity in the experimental group. PCV13i induced higher IgG geometric mean concentrations (GMCs) for serotypes 3, 7F, and 19F (p < 0.05), whereas the control group showed higher GMCs for serotypes 1, 5, 6A, and 14 (p < 0.05). Opsonophagocytic activity (OPA)-related geometric mean titers (GMTs) were superior for PCV13i against serotypes 7F (39,583 vs. 17,249, p < 0.001) and 19F (1517 vs. 983, p = 0.028), but lower for serotype 5 (13 vs. 93, p < 0.001). Conclusions: PCV13i demonstrated non-inferior immunogenicity and an acceptable safety profile in 12–23-month-old children. Full article

Background: The minimized pan-coronavirus (CoV) vaccine-1 developed by our laboratory contained pDNA sequences of feline coronavirus serotype-1 (FCoV1) and SARS-CoV2 (SCoV2) spike B-cell epitopes plus FCoV/SCoV2-conserved, CoV-specific polymerase cytotoxic T-lymphocyte (CTL) epitopes formulated in lipid nanoparticle (LNP). Only FCoV2 infects feline cell lines needed for developing native challenge inoculum that causes feline infectious peritonitis (FIP). Hence, Pilot Study 1 evaluated the therapeutic efficacy and safety of the pan-CoV vaccine-1 in feline immunodeficiency virus (FIV)-infected cats, with or without FCoV1 coinfection. Pilot Study 2 evaluated the cross-protective effect of pan-CoV vaccines in specific-pathogen-free (SPF) cats against intranasal challenge with FIP virus serotype 2 (FIPV2). Methods: In Study 1, we vaccinated two FIV-infected cats (one negative and another positive for FCoV1 coinfection) intramuscularly twice with CTL epitopes-LNP vaccine and later twice with pan-CoV vaccine-1. Controls included two unvaccinated FIV-infected cats with or without FCoV1 coinfection. Study 2 assessed the sequential vaccinations of three pan-CoV vaccines in four SPF cats. The first two vaccinations were with pan-CoV vaccine-2, followed by pan-CoV vaccine-3 (twice), and lastly with pan-CoV vaccine-1 (once). Three SPF controls included two cats immunized with LNP and one lacking any immunization. Pan-CoV vaccine-2 contained pDNAs with modified FCoV1/SCoV2 B-cell epitopes plus CTL epitopes in LNP. Pan-CoV vaccine-3 contained only pDNAs with FCoV1 B-cell epitopes plus CTL epitopes in LNP. Results: Study 1 demonstrated no adverse effect with 25 μg and 50 μg CTL epitopes-LNP vaccine and 50 μg pan-CoV vaccine-1. However, 100 μg pan-CoV vaccine-1 caused fever 24 h later, which was resolved by a single Meloxicam treatment. Both vaccinees developed cross-FCoV2 neutralizing antibodies (XNAbs), immunoblot binding antibodies (bAbs) to FCoV1 receptor-binding domain (RBD), and T-cell responses to FCoV1 RBD, whereas one vaccinee also developed bAbs to SCoV2 RBD. Study 2 demonstrated no adverse effects after each vaccination. Three vaccinees developed low-titer XNAbs and bAbs to FCoV2 spike-2 by the fourth vaccination. Upon challenge, all cats developed FCoV2 NAbs and bAbs to FCoV2 nucleocapsid and RBD. High vaccine-induced T-cell responses to FCoV1 RBD and T-cell mitogen responses declined with an increase in responses to FCoV2 RBD at three weeks post-challenge. Two of the three controls died from FIP, whereas one vaccinee, with the lowest vaccine-induced immunity, died from skin vasculitis lesions and detection of FIPV2 infection by semi-nested RT-snPCR in feces. Conclusions: In Pilot Study 1, the pan-CoV vaccine-LNP dose of 50 μg had no adverse effects, but adverse effects were observed at 100 μg dose. In Pilot Study 2, the FCoV1-based B-cell vaccine(s) induced low levels of XNAbs against FIPV2 and delayed challenge infection against high-dose FIPV2. The high-dose FIPV2 infections in the vaccinated and control cats started to clear, by single housing at 23–26 weeks post-challenge, whereas two cats in Pilot Study 1 cleared natural FCoV1 transmission by 26 weeks post-infection. Full article

Background/Objectives: The 20-valent pneumococcal conjugate vaccine (PCV20) was approved for use in children and infants on the basis of studies comparing its safety and immunogenicity with those of the 13-valent vaccine (PCV13). PCV20 offers expanded coverage of seven additional serotypes. This meta-analysis aimed to summarize the available evidence on the comparative immunogenicity between PCV20 and PCV13. Methods: A systematic search of the PubMed, Web of Science, Scopus, Cochrane, and ClinicalTrials.gov databases was conducted in September 2024. The following inclusion criteria were used: (i) design: randomized clinical trials; (ii) outcomes: studies that included immunogenicity outcomes; (iii) compared vaccines: any study directly comparing the immunogenicity of PCV20 and PCV13; and (iv) population: infant population <2 years of age. No language or temporal restrictions were applied in the study. A random-effects meta-analysis was conducted via the Hartung–Knapp–Sidik–Jonkman method, with subgroup analyses according to the serotype and vaccination schedule (3 + 1 and 2 + 1). We used the revised Cochrane risk of bias 2 tool (RoB 2.0) to assess the risk of bias. The following parameters of immunogenicity were estimated: (i) the pooled geometric mean ratio (GMR PCV20/PCV13) of serotype-specific pneumococcal anticapsular antibodies, (ii) the pooled difference (PCV20-PCV13) in the percentage (DP) of participants who achieved predefined antibody levels for each serotype, and (iii) the pooled geometric mean titres (GMTs) of serotype-specific opsonophagocytic activity (OPA) in PCV20 and PCV13, along with their 95% confidence intervals (95% CIs). Results: Four studies (4093 infants aged 42–180 days) that compared the PCV20 and PCV13 vaccines, published between 2021 and 2024, were included in this meta-analysis. The immunogenicity of both groups was compared one month after the primary series and one month after the booster dose. The pooled results indicated that PCV20 elicited lower immune responses for the 13 serotypes shared with PCV13, according to the GMR and OPA outcomes. For the DP outcome, no statistically significant differences were observed between the two groups. Immune responses were higher for the additional serotypes in the PCV20 group; however, these differences were not statistically significant for all serotypes. Conclusions: This meta-analysis offers an overview of the evidence on the comparative immunogenicity of PCV20 and PCV13. Although some outcomes indicate that PCV20 elicits lower immune responses for the 13 serotypes shared with PCV13, it provides immunity against seven additional serotypes associated with IPD. Further studies are warranted to strengthen the evidence base, and continuous IPD surveillance remains essential to monitor shifts in serotype prevalence, assess the impact of current and future vaccines, and guide vaccine policy recommendations. Full article

Streptococcus pneumoniae is a major opportunistic pathogen and a leading cause of severe infections in infants under two years of age. Human milk oligosaccharides (HMOs), key bioactive components of breast milk, possess immunomodulatory and antimicrobial properties. In this study, the antipneumococcal effects of HMOs are investigated across multiple S. pneumoniae serotypes, focusing on concentration-dependent activity and underlying mechanisms. Growth inhibition and bacterial viability were evaluated using growth curve analysis and colony-forming unit (CFU) assays. HMOs inhibited pneumococcal growth in a concentration-dependent manner, with suppression observed at 1.5–2.5 mg/mL and complete killing at 5 mg/mL for all serotypes. Nonencapsulated strains were more sensitive, with inhibition at 1 mg/mL. In the CFU assays, killing occurred at 1.25–5 mg/mL depending on the strain. At physiologically relevant colostrum concentrations (20–25 mg/mL), HMOs achieved complete bactericidal effects across all the tested strains. In contrast, lactose at equivalent doses showed no measurable antimicrobial activity, confirming the specificity of the observed effects. Overall, HMOs exhibit serotype-independent antipneumococcal activity, possibly through interference with bacterial adhesion or metabolic disruption. These findings suggest a potential role for HMOs as adjunctive agents in the prevention of pneumococcal infections in vulnerable populations, such as infants, and warrant further in vivo studies to validate these effects and explore clinical applications. Full article