Global epidemiology of asymptomatic colonisation of methicillin-resistant Staphylococcus aureus in the upper respiratory tract of young children: a systematic review and meta-analysis

OBJECTIVE

To estimate the global prevalence of asymptomatic colonisation, and determine the associated risk factors, antibiotic resistance and genotypes of methicillin-resistant Staphylococcus aureus (MRSA) in the upper respiratory tract of young children.

DESIGN

Four bibliometric databases were searched for publications between 2010 and 2022 according to the protocol registered in PROSPERO. Cross-sectional or cohort studies describing the prevalence of asymptomatic colonisation of S. aureus and MRSA in young children were included. Data extraction and analysis were carried out by two reviewers independently according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 statement. Pooled prevalence was estimated using a random effects model.

SETTING AND STUDIES

We included studies where children without respiratory tract infection or Staphylococcal infection were recruited from the community, children's institutions (ie, nurseries, kindergartens, daycare centres and preschools) and healthcare centre visits and assessed for asymptomatic colonisation with S. aureus and MRSA.

MAIN OUTCOME MEASURES

The pooled prevalence of asymptomatic colonisation of S. aureus and MRSA of young children globally.

RESULTS

In this systematic review and meta-analysis of 21 416 young children, the pooled global prevalence of asymptomatic S. aureus colonisation was 25.1% (95% CI 21.4 to 28.8) and MRSA colonisation was 3.4% (95% CI 2.8 to 4.1). The clones of MRSA strains included healthcare-associated MRSA, community-associated MRSA and livestock-associated MRSA.

CONCLUSION

This study provides evidence of increased MRSA colonisation globally among young children, underlining the critical role of asymptomatic carriers in MRSA transmission and the need for control measures.

PROSPERO REGISTRATION NUMBER

CRD 42022328385.

Is there a role of faecal microbiota transplantation in reducing antibiotic resistance burden in gut? A systematic review and Meta-analysis

OBJECTIVES

The aim of current systematic review and meta-analysis is to provide insight into the therapeutic efficacy of fecal microbiota transplantation (FMT) for the decolonization of antimicrobial-resistant (AMR) bacteria from the gut.

METHODS

The protocol for this Systematic Review was prospectively registered with PROSPERO (CRD42020203634). Four databases (EMBASE, MEDLINE, SCOPUS, and WEB of SCIENCE) were consulted up until September 2020. A total of fourteen studies [in vivo (n = 2), case reports (n = 7), case series without control arm (n = 3), randomized clinical trials (RCT, n = 2)], were reviewed. Data were synthesized narratively for the case reports, along with a proportion meta-analysis for the case series studies (n = 102 subjects) without a control arm followed by another meta-analysis for case series studies with a defined control arm (n = 111 subjects) for their primary outcomes.

RESULTS

Overall, seven non-duplicate case reports (n = 9 participants) were narratively reviewed and found to have broad AMR remission events at the 1-month time point. Proportion meta-analysis of case series studies showed an overall 0.58 (95% CI: 0.42-0.74) AMR remission. Additionally, a significant difference in AMR remission was observed in FMT vs treatment naïve (RR = 0.44; 95% CI: 0.20-0.99) and moderate heterogeneity (I2=65%). A subgroup analysis of RCTs (n = 2) revealed FMT with further benefits of AMR remission with low statistical heterogeneity (RR = 0.37; 95% CI: 0.18-0.79; I2 =23%).

CONCLUSION

More rigorous RCTs with larger sample size and standardized protocols on FMTs for gut decolonization of AMR organisms are warranted.KEY MESSAGEExisting studies in this subject are limited and of low quality with moderate heterogeneity, and do not allow definitive conclusions to be drawn.More rigorous RCTs with larger sample size and standardized protocols on FMTs for gut decolonization of AMR organisms are warranted.

A Novel Dicationic Boron Dipyrromethene-based Photosensitizer for Antimicrobial Photodynamic Therapy against Methicillin-Resistant Staphylococcus aureus

Background

We report herein the synthesis of a novel dicationic boron dipyrromethene derivative (compound 3) which is symmetrically substituted with two trimethylammonium styryl groups.

Methods

The antibacterial photodynamic activity of compound 3 was determined against sixteen methicillin-resistant Staphylococcus aureus (MRSA) strains, including four ATCC type strains (ATCC 43300, ATCC BAA-42, ATCC BAA-43, and ATCC BAA-44), two mutant strains [AAC(6’)-APH(2”) and RN4220/pUL5054], and ten non-duplicate clinical strains of hospital- and community-associated MRSA. Upon light irradiation, the minimum bactericidal concentrations of compound 3 were in the range of 1.56-50 µM against all the sixteen MRSA strains. Interestingly, compound 3 was not only more active than an analogue in which the ammonium groups are not directly connected to the n-conjugated system (compound 4), but also showed significantly higher (p < 0.05) antibacterial potency than the clinically approved photosensitizer methylene blue. The skin irritation of compound 3 during topical application was tested on human 3-D skin constructs and proven to be non-irritant in vivo at concentrations below 1.250 mM. In the murine MRSA infected wound study, the colony forming unit reduction of compound 3 + PDT group showed significantly (p < 0.05) higher value (>2.5 log₁₀) compared to other test groups except for the positive control.

Conclusion

In conclusion, the present study provides a scientific basis for future development of compound 3 as a potent photosensitizer for photodynamic therapy for MRSA wound infection.

Swine methicillin-resistant Staphylococcus aureus carrying toxic-shock syndrome toxin gene in Hong Kong, China

We report a SCCmec II, ST39 methicillin-resistant Staphylococcus aureus isolate from pigs that harboured toxic-shock syndrome toxin gene (tsst-1). The gene was located in a rare pathogenicity island SaPI68111, which also carried enterotoxin genes that can cause fatal infections. Pigs may potentially serve as a reservoir for MRSA dissemination.

Monosubstituted tricationic Zn(II) phthalocyanine enhances antimicrobial photodynamic inactivation (aPDI) of methicillin-resistant Staphylococcus aureus (MRSA) and cytotoxicity evaluation for topical applications: in vitro and in vivo study

Antimicrobial photodynamic therapy (aPDT) is an innovative approach to combat multi-drug resistant bacteria. It is known that cationic Zn(II) phthalocyanines (ZnPc) are effective in mediating aPDT against methicillin-resistant Staphylococcus aureus (MRSA). Here we used ZnPc-based photosensitizer named ZnPcE previously reported by our research group to evaluate its aPDT efficacy against broad spectrum of clinically relevant MRSAs. Remarkably, in vitro anti-MRSA activity was achieved using near-infrared (NIR, >610 nm) light with minimal bactericidal concentrations ranging <0.019-0.156 µM against the panel of MRSAs. ZnPcE was not only significantly (p < .05) more potent than methylene blue, which is a clinically approved photosensitizer but also demonstrated low cytotoxicity against human fibroblasts cell line (Hs-27) and human immortalized keratinocytes cell line (HaCaT). The toxicity was further evaluated on human 3-D skin constructs and found ZnPcE did not manifest in vivo skin irritation at ≤7.8 µM concentration. In the murine MRSA wound model, ZnPcE with PDT group demonstrated > 4 log10 CFU reduction and the value is significantly higher (p < .05) than all test groups except positive control. To conclude, results of present study provide a scientific basis for future clinical evaluation of ZnPcE-PDT on MRSA wound infection.

Synthesis and In Vitro Photodynamic Activity of Cationic Boron Dipyrromethene-Based Photosensitizers against Methicillin-Resistant Staphylococcus aureus

A series of cationic boron dipyrromethene (BODIPY) derivatives were synthesized and characterized with various spectroscopic methods. Having the ability to generate singlet oxygen upon irradiation, these compounds could potentially serve as photosensitizers for antimicrobial photodynamic therapy. Of the five BODIPYs being examined, the dicationic aza-BODIPY analogue (compound 5) demonstrated the highest potency against a broad spectrum of clinically relevant methicillin-resistant Staphylococcus aureus (MRSA), including four ATCC-type strains (ATCC 43300, ATCC BAA-42, ATCC BAA-43, and ATCC BAA-44), two strains carrying specific antibiotic resistance mechanisms [-AAC(6')-APH(2") and RN4220/pUL5054], and ten non-duplicate clinical strains from hospital- and community-associated MRSAs of the important clonal types ST239, ST30, and ST59, which have previously been documented to be prevalent in Hong Kong and its neighboring countries. The in vitro anti-MRSA activity of compound 5 was achieved upon irradiation with near-infrared light (>610 nm) with minimal bactericidal concentrations (MBCs) ranging from 12.5 to 25 µM against the whole panel of MRSAs, except the hospital-associated MRSAs for which the MBCs were in the range of 50-100 µM. Compound 5 was significantly (p < 0.05) more potent than methylene blue, which is a clinically approved photosensitizer, indicating that it is a promising antimicrobial agent that is worthy of further investigation.

Contemporary approaches and future perspectives of antibacterial photodynamic therapy (aPDT) against methicillin-resistant Staphylococcus aureus (MRSA): A systematic review

The high prevalence of methicillin-resistant Staphylococcus aureus (MRSA) causing skin and soft tissue infections in both the community and healthcare settings challenges the limited options of effective antibiotics and motivates the search for alternative therapeutic solutions, such as antibacterial photodynamic therapy (aPDT). While many publications have described the promising anti-bacterial activities of PDT in vitro, its applications in vivo and in the clinic have been very limited. This limited availability may in part be due to variabilities in the selected photosensitizing agents (PS), the variable testing conditions used to examine anti-bacterial activities and their effectiveness in treating MRSA infections. We thus sought to systematically review and examine the evidence from existing studies on aPDT associated with MRSA and to critically appraise its current state of development and areas to be addressed in future studies. In 2018, we developed and registered a review protocol in the International Prospective Register of Systematic Reviews (PROSPERO) with registration No: CRD42018086736. Three bibliographical databases were consulted (PUBMED, MEDLINE, and EMBASE), and a total of 113 studies were included in this systematic review based on our eligibility criteria. Many variables, such as the use of a wide range of solvents, pre-irradiation times, irradiation times, light sources and light doses, have been used in the methods reported by researchers, which significantly affect the inter-study comparability and results. On another note, new approaches of linking immunoglobulin G (IgG), antibodies, efflux pump inhibitors, and bacteriophages with photosensitizers (PSs) and the incorporation of PSs into nano-scale delivery systems exert a direct effect on improving aPDT. Enhanced activities have also been achieved by optimizing the physicochemical properties of the PSs, such as the introduction of highly lipophilic, poly-cationic and site-specific modifications of the compounds. However, few in vivo studies (n = 17) have been conducted to translate aPDT into preclinical studies. We anticipate that further standardization of the experimental conditions and assessing the efficacy in vivo would allow this technology to be further applied in preclinical trials, so that aPDT would develop to become a sustainable, alternative therapeutic option against MRSA infection in the future.