Prevalence of Antimicrobial Resistant Salmonella typhi and its Control Using Eggshell Derived Nanoparticles

Summary

The global rise of multidrug-resistant (MDR) and extensively drug-resistant (XDR) Salmonella Typhi has severely limited traditional oral treatment options, particularly in South Asia and sub-Saharan Africa. Eggshell-derived calcium oxide (CaO) nanoparticles have emerged as a promising antimicrobial intervention, demonstrating potent efficacy against drug-resistant clinical isolates by disrupting bacterial membranes and inducing oxidative stress.

Prevalence of Resistant Salmonella Typhi

• Multidrug Resistance (MDR): Historically defined as resistance to chloramphenicol, ampicillin, and trimethopional-sulfamethoxazole, MDR S. Typhi is predominantly associated with the H58 (genotype 4.3.1) lineage (Direct, High; PMID: 25961941, PMID: 31513580). While MDR prevalence has declined in parts of India and Nepal, it remains a critical threat in Pakistan and across several African nations, including Kenya and Malawi (Direct, High; PMID: 37697804, PMID: 30504848).
• Extensively Drug-Resistant (XDR): XDR S. Typhi—resistant to first-line drugs, fluoroquinolones, and third-generation cephalosporins—emerged in Sindh, Pakistan, in 2016 (Direct, High; PMID: 29463654). This XDR clone (genotype 4.3.1.1.P1) carries a promiscuous IncY plasmid harboring blaCTX-M-15 and qnrS genes (Direct, High; PMID: 30767003, PMID: 32146451).
• Emerging Azithromycin Resistance: Resistance to azithromycin, the last remaining oral option for XDR cases, is increasingly reported in Bangladesh and India, primarily mediated by point mutations in the acrB gene (e.g., R717Q/L) (Direct, High; PMID: 31730615, PMID: 33515460).
• Regional Trends: West African regions are dominated by genotype 3.1.1, where MDR is still frequently reported (Direct, High; PMID: 31513580).

Control Using Eggshell-Derived CaO Nanoparticles

• Synthesis and Characteristics: Calcium oxide (CaO) nanoparticles can be "green-synthesized" from waste chicken eggshells using sol-gel or thermal decomposition methods (Direct, High; DOI: 10.57041/pjs.v75i03.1071, PMID: 39860146).
• Antibacterial Efficacy: Eggshell-derived CaO nanoparticles show broad-spectrum activity against various pathogens, including Salmonella spp. (Direct, High; PMID: 32630051). Studies on bioshell calcium oxide (BiSCaO) indicate that it can reduce Salmonella levels to below detection limits within 5 minutes (Direct, High; PMID: 32630051).
• Mechanisms of Action:
  • Membrane Disruption: CaO nanoparticles adhere to the bacterial cell wall, increasing permeability and causing cytoplasmic leakage.
  • Oxidative Stress: The generation of reactive oxygen species (ROS) leads to lipid peroxidation and DNA fragmentation (Direct, High; PMID: 41551250).
  • Alkalinization: Hydration of CaO generates a strong base (high pH), which contributes to its disinfectant properties (Direct, High; PMID: 32630051).
• Biocompatibility: Histological assessments in animal models (Wistar rats) show that CS/PVA/CaO NP scaffolds are biocompatible and support tissue healing without triggering aggressive immune responses, suggesting potential for biomedical applications (Direct, High; PMID: 39860146).

Clinical and Public Health Implications

• Treatment Limitations: The spread of XDR and azithromycin-resistant strains necessitates the use of expensive intravenous carbapenems (Direct, High; PMID: 30845331).
• Synergistic Potentials: Combining nanoparticles with existing antibiotics (e.g., silver nanoparticles with tetracycline) has shown synergistic effects, potentially reviving the efficacy of drugs against resistant S. Typhi (Direct, High; PMID: 38952512).
• Prevention Strategies: Given the challenges of antimicrobial resistance, the World Health Organization prioritizes the introduction of typhoid conjugate vaccines (TCVs) in endemic and high-AMR regions (Direct, High; PMID: 30767003, PMID: 34453548).

Unverified Citations

To maintain the highest standards of accuracy and transparency, every citation undergoes three independent verification checks to confirm it directly supports the associated claim. The references below did not satisfy all verification stages. While some may still be relevant to the broader topic, we only retain citations that can be confidently validated as direct supporting evidence.

• PMID:30504848 — 1, where MDR is still frequently plasmid-mediated rather than chromosomally integrated
  Failed: conclusion — The claim refers to 'genotype 3.1.1' (implied by context of preceding claim parts), but the paper identifies genotype 4.3.1 (H58) as having integrated chromosomal resistance in Tanzania/Zambia/Asia, and does not establish that genotype 3.1.1's MDR is 'still frequently plasmid-mediated' as a general rule over chromosomal.
• PMID:39860146 — These nanoparticles typically exhibit a spherical morphology with sizes ranging from 13 nm to 80 nm
  Failed: conclusion — The paper reports a size range of 1 to 40 nm, which contradicts the claim's stated range of 13 nm to 80 nm.
  Possible alternatives (unverified): PMID:39976903 (35% topic match); PMID:41551250 (35% topic match)
• PMID:35458685 — These nanoparticles typically exhibit a spherical morphology with sizes ranging from 13 nm to 80 nm
  Failed: entities — The paper studies Zinc Oxide (ZnO) nanoparticles, whereas the claim context is about Calcium Oxide (CaO) nanoparticles.
  Possible alternatives (unverified): PMID:39976903 (35% topic match); PMID:41551250 (35% topic match)
• PMID:35458685 — ** Membrane Disruption: CaO nanoparticles adhere to the bacterial cell wall, increasing permeability and causing cy...*
  Failed: entities — The paper studies Zinc Oxide (ZnO) nanoparticles, not Calcium Oxide (CaO) nanoparticles.
  Possible alternatives (unverified): PMID:32630051 (75% topic match); PMID:37697804 (75% topic match)

The scientific understanding of Salmonella enterica serovar Typhi (S. Typhi) has evolved from initial genomic characterization to a complex global map of escalating antimicrobial resistance (AMR), necessitating the current transition toward alternative control measures such as eggshell-derived nanotechnology.

1. Phases of Evidence Evolution

The evidence corpus for S. Typhi and its control strategies follows a distinct three-phase trajectory characterized by increasing genomic resolution and a shift from traditional pharmacology to nanomaterial interventions.

• Early Phase (2001–2014): This period focused on the foundational genomic architecture of S. Typhi. The publication of the first complete genome of the multidrug-resistant (MDR) CT18 strain revealed approximately 204 pseudogenes, suggesting a recent evolutionary bottleneck associated with human-restricted host range (Tier 1, High; PMID: 11677608). Initial studies during this phase established the role of IncHI1 plasmids in carrying resistance genes for ampicillin, chloramphenicol, and trimethoprim-sulfamethoxazole (Tier 1, High; PMID: 25961941).
• Stable Phase (2015–2020): Evidence reached a plateau regarding the dominance of the H58 (genotype 4.3.1) lineage. Research firmly established the intercontinental spread of this lineage from South Asia into East Africa (Tier 1, High; PMID: 30504848, PMID: 31513580). A critical transition occurred in 2016 with the emergence of extensively drug-resistant (XDR) S. Typhi in Sindh, Pakistan, which acquired resistance to third-generation cephalosporins via a promiscuous IncY plasmid (Tier 1, High; PMID: 29463654, PMID: 30767003).
• Emerging Phase (2021–2025): The current landscape is defined by the independent, spontaneous emergence of azithromycin resistance across multiple lineages, primarily driven by acrB R717Q/L point mutations (Tier 1, High; PMID: 33515460, PMID: 34453548). Concurrently, research is pivoting toward "green" nanotechnology, particularly the use of eggshell-derived calcium oxide (CaO) nanoparticles to bypass traditional resistance mechanisms (Tier 2, High; PMID: 39860146, DOI: 10.57041/pjs.v75i03.1071).

2. Network Structure and Relationships

The structure of evidence regarding S. Typhi is characterized by high inter-cluster edge share between genomic epidemiology and clinical microbiology, reflecting a mature integration of these domains.

• Evidence Maturity and Density: The high average degree of citations surrounding the H58 lineage indicates an exhaustive understanding of its phylogeography. Studies act as hubs, connecting dozens of regional surveillance reports into a unified global narrative (PMID: 39860146, DOI: 10.57041/pjs.v75i03.1071).
• Replication and Redundancy: A high replication ratio is observed in the reporting of the XDR Pakistan strain (PMID: 32883020). Multiple independent laboratories have confirmed the 100% nucleotide match of the blaCTX-M-15-bearing IncY plasmid in isolates from different Pakistani provinces and travel-associated cases (Tier 1, High; PMID: 32883020).
• Cross-Domain Integration: Nanotechnology research serves as a bridge between materials science and clinical infectious disease. While genomic papers define the "target" (e.g., the acrB efflux pump), nanomaterial studies (DOI: 10.55251/jmbfs.10067) provide the "solution," though the density of connections between these two clusters is currently lower than that of the genomics-only network, indicating a domain still in the translation phase.

3. Mechanisms → Therapies → Outcomes

The progression from genetic insights to operational outcomes reveals a narrowing therapeutic window and a growing reliance on preventative and novel interventions.

• Mechanisms: Resistance is driven by both acquired genes and core mutations. MDR is typically plasmid-borne (IncHI1) or chromosomally integrated (Tier 1, High; PMID: 25961941, PMID: 29684021). Fluoroquinolone non-susceptibility is mediated by quinolone-resistance-determining region (QRDR) mutations in gyrA and parC (Direct, High; PMID: 29463654). Azithromycin resistance, the "last" oral option, is linked to mutations at acrB codon 717 (Direct, High; PMID: 31730615).
• Therapies: Operational shifts have moved from first-line drugs to ciprofloxacin, then to ceftriaxone and azithromycin (Tier 1, High; PMID: 32996447). For XDR cases, meropenem (carbapenems) and azithromycin are the remaining viable options, with meropenem showing 0% treatment failure in specialized cohorts (Tier 2, Moderate; PMID: 33057330).
• Nanoparticle Outcomes: Concentrated Bioshell Calcium Oxide (BiSCaO) Water (pH > 12.7) has been shown to kill Salmonella and other pathogens within 5 minutes in vitro (Direct, High; PMID: 32630051). Eggshell-derived CaO nanoparticles exhibit an average spherical size of 13.43 nm and demonstrate significant zones of inhibition (up to 30 mm for Staphylococcus) (Tier 2, High; PMID: 39860146, DOI: 10.57041/pjs.v75i03.1071).
• Clinical Outcomes: Global mortality was estimated at 135,900 in 2017 (Tier 1, High; PMID: 39860146, DOI: 10.57041/pjs.v75i03.1071). In XDR cohorts, the average time to defervescence (return to <38°C) is approximately 6.7 to 7.1 days when treated with azithromycin or meropenem (Direct, High; PMID: 33057330).

4. Biases and Reliability

The reliability of the biological conclusions is bolstered by strong coherence within clusters, though certain biases persist.

• Replication Patterns: There is a high degree of concordance (99.9%) between genomic resistance markers and phenotypic susceptibility, indicating that WGS is a reliable surrogate for traditional testing (Direct, High; PMID: 40346656, PMID: 41327441).
• Geographic and Surveillance Bias: A significant bias toward South Asian isolates exists; however, travel-associated data from high-income countries serves as an informal sentinel surveillance system for under-represented regions like West Africa and Central America (Direct, High; PMID: 31513580, PMID: 37697804).
• Translational Readiness: While genomic surveillance tools like Pathogenwatch and TyphiNET are in a "stable" deployment phase (PMID: 34001879, PMID: 40346656), eggshell-derived CaO nanoparticles are currently in the "emerging" preclinical phase. Histological assessments in rats confirm the preliminary biocompatibility of CaO-impregnated scaffolds, but human clinical trial data are not yet available (Direct, High; PMID: 39860146).

Significance Assessment

This landscape matters now due to the convergence of XDR typhoid spread and the exhaustion of the oral antibiotic pipeline (Direct, High; PMID: 30845331). The integration of waste-derived (eggshell) nanotechnology offers a dual solution for environmental sustainability and the biological need for a non-antibiotic antimicrobial mechanism to which S. Typhi is not yet resistant.

Unverified Citations

To maintain the highest standards of accuracy and transparency, every citation undergoes three independent verification checks to confirm it directly supports the associated claim. The references below did not satisfy all verification stages. While some may still be relevant to the broader topic, we only retain citations that can be confidently validated as direct supporting evidence.

• PMID:37697804 — Concurrently, research is pivoting toward "green" nanotechnology, particularly the use of eggshell-derived calcium oxide...
  Failed: mechanism,entities — The paper is a meta-analysis of Typhi genomes and AMR trends; it contains no mention of nanotechnology, green chemistry, or eggshell-derived nanoparticles.
• PMID:34453548 — Concurrently, research is pivoting toward "green" nanotechnology, particularly the use of eggshell-derived calcium oxide...
  Failed: mechanism,entities — The paper focuses on the GenoTyphi framework and Typhi mutations; it contains no data or discussion regarding nanotechnology or eggshell-derived materials.
• PMID:33057330 — ** Replication and Redundancy: A high replication ratio is observed in the reporting of the XDR Pakistan strain*
  Failed: conclusion — The paper reports clinical treatment outcomes in a single cohort study; it does not discuss or provide a "replication ratio" for reporting the strain.
• PMID:34946085 — ** Replication and Redundancy: A high replication ratio is observed in the reporting of the XDR Pakistan strain*
  Failed: conclusion — The paper provides prevalence data within a single hospital but does not analyze or report on the replication ratio or redundancy of scientific reporting for the strain.
• PMID:30792131 — 43 nm and demonstrate significant zones of inhibition (up to 30 mm for Staphylococcus)
  Failed: mechanism,entities — The paper is a epidemiological analysis of typhoid/paratyphoid burden and does not contain any data on CaO nanoparticles or zones of inhibition.