SARS-CoV-2 Spike Protein-Derived Cyclic Peptides as Modulators of Spike Interaction with GRP78.

The human glucose-regulated protein GRP78 is a human chaperone that translocactes to the cell surface when cells are under stress. Theoretical studies suggested it could be involved in SARS-CoV-2 virus entry to cells. In this work, we used in vitro surface plasmon resonance-based assays to show that human GRP78 indeed binds to SARS-CoV-2 spike protein. We have designed and synthesised cyclic peptides based on the loop structure of amino acids 480-488 of the SARS-CoV-2 spike protein S1 domain from the Wuhan and Omicron variants and showed that both peptides bind to GRP78. Consistent with the greater infectiousness of the Omicron variant, the Omicron-derived peptide displays slower dissociation from the target protein. Both peptides significantly inhibit the binding of wild-type S1 protein to the human protein GRP78 suggesting that further development of these cyclic peptide motifs may provide a viable route to novel anti-SARS-CoV-2 agents.

Oral lichen planus and lichenoid lesions - challenges and pitfalls for the general dental practitioner.

Lichen planus is a chronic, mucocutaneous inflammatory condition which, due to its prevalence, will be familiar to the dental profession. However, diverse forms of presentation, important differential diagnosis, potential malignant change and monitoring requirements often result in challenges for those in primary care. This paper looks to examine these challenges and provide information to support those who are involved in recognition and management of patients with lichen planus.

Methods for SARS-CoV-2 hospital disinfection, in vitro observations.

Introduction: Escalation of chemical disinfection during the COVID-19 pandemic has raised occupational hazard concerns. Alternative and potentially safer methods such as ultraviolet-C (UVC) irradiation and ozone have been proposed, notwithstanding the lack of standardized criteria for their use in the healthcare environment. Aim: Compare the virucidal activity of 70% ethanol, sodium dichloroisocyanurate (NaDCC), chlorhexidine, ozonated water, UVC-222 nm, UVC-254 nm against three SARS-CoV-2 variants of concern cultured in vitro. Methods: Inactivation of three SARS-CoV-2 variants (alpha, beta, gamma) by the following chemical methods was tested: ethanol 70%, NaDCC (100 ppm, 500 ppm, 1000 ppm), chlorhexidine (2%, 1% and 0.5%), ozonated water 7 ppm. For irradiation, a je2Care 222nm UVC Lamp was compared to a Sylvania G15 UV254 nm lamp. Results: Viral inactivation by >3 log was achieved with ethanol, NaDCC and chlorhexidine. The minor virucidal effect of ozonated water was <1 log. Virus treatment with UVC-254 nm reduced viral activity by 1-5 logs with higher inactivation after exposure for 3 minutes compared to 6 seconds. For all three variants, under equivalent conditions, exposure to UVC-222 nm did not achieve time-dependent inactivation as was observed with treatment with UVC-254 nm. Conclusion: The virucidal activity on replication-competent SARS-CoV-2 by conventional chemical methods, including chlorhexidine at concentrations as low as 0.5%, was not matched by UVC irradiation, and to an even lesser extent by ozonated water treatment.

Venomous gland transcriptome and venom proteomic analysis of the scorpion Androctonus amoreuxi reveal new peptides with anti-SARS-CoV-2 activity.

The recent COVID-19 pandemic shows the critical need for novel broad spectrum antiviral agents. Scorpion venoms are known to contain highly bioactive peptides, several of which have demonstrated strong antiviral activity against a range of viruses. We have generated the first annotated reference transcriptome for the Androctonus amoreuxi venom gland and used high performance liquid chromatography, transcriptome mining, circular dichroism and mass spectrometric analysis to purify and characterize twelve previously undescribed venom peptides. Selected peptides were tested for binding to the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein and inhibition of the spike RBD - human angiotensin-converting enzyme 2 (hACE2) interaction using surface plasmon resonance-based assays. Seven peptides showed dose-dependent inhibitory effects, albeit with IC50 in the high micromolar range (117-1202 µM). The most active peptide was synthesized using solid phase peptide synthesis and tested for its antiviral activity against SARS-CoV-2 (Lineage B.1.1.7). On exposure to the synthetic peptide of a human lung cell line infected with replication-competent SARS-CoV-2, we observed an IC50 of 200 nM, which was nearly 600-fold lower than that observed in the RBD - hACE2 binding inhibition assay. Our results show that scorpion venom peptides can inhibit the SARS-CoV-2 replication although unlikely through inhibition of spike RBD - hACE2 interaction as the primary mode of action. Scorpion venom peptides represent excellent scaffolds for design of novel anti-SARS-CoV-2 constrained peptides. Future studies should fully explore their antiviral mode of action as well as the structural dynamics of inhibition of target virus-host interactions.

Chlorhexidine Resistance or Cross-Resistance, That Is the Question.

Chlorohexidine (CHX) is a widely used biocide in clinical and household settings. Studies over the last few decades have reported CHX resistance in different bacterial species, but at concentrations well below those used in the clinical setting. Synthesis of these findings is hampered by the inconsistent compliance with standard laboratory procedures for biocide susceptibility testing. Meanwhile, studies of in vitro CHX-adapted bacteria have reported cross-resistance between CHX and other antimicrobials. This could be related to common resistance mechanisms of CHX and other antimicrobials and/or the selective pressure driven by the intensive use of CHX. Importantly, CHX resistance and cross-resistance to antimicrobials should be investigated in clinical as well as environmental isolates to further our understanding of the role of CHX in selection of multidrug resistance. Whilst clinical studies to support the hypothesis of CHX cross-resistance with antibiotics are currently lacking, we recommend raising the awareness of healthcare providers in a range of clinical disciplines regarding the potential adverse impact of the unfettered use of CHX on tackling antimicrobial resistance.

Disease severity scoring systems in mucosal lichen planus: A systematic review.

Several scoring systems have been developed to evaluate disease severity in mucosal lichen planus, but only a few have been validated to ensure reproducible and accurate assessment of disease severity. The current systematic review was undertaken to identify clinical severity scoring systems in mucosal lichen planus that have undergone validity or reliability testing and to describe their operating characteristics. We performed a bibliographic search in five databases from their inception to October 2022 for severity scoring systems in mucosal lichen planus that have undergone validity or reliability tests. Quality assessment was conducted using the Joanna Briggs Institute Critical Appraisal tools. We have included 118 studies and identified 11 clinical severity scoring systems for oral lichen planus that have undergone validity or reliability testing. Of these, the most reported were the Thongprasom score, the Oral Disease Severity Score (ODSS) and the REU (Reticular/hyperkeratotic, Erosive/erythematous, Ulcerative) scoring systems. We did not identify clinical scoring systems for extraoral mucosal lichen planus that have undergone validity or reliability testing. The ODSS and REU scoring systems have undergone the highest number of validation attempts and reliability assessments for oral lichen planus respectively. However, we have identified numerous factors that have hampered the universal adoption of a standardised scoring system. There is a need for the development and validation of scoring systems for extraoral mucosal lichen planus.

Comprehensive Study of Antiretroviral Drug Permeability at the Cervicovaginal Mucosa via an In Vitro Model.

Modulation of drug transporter activity at mucosal sites of HIV-1 transmission may be exploited to optimize retention of therapeutic antiretroviral drug concentrations at target submucosal CD4+ T cells. Previously, we showed that darunavir was a substrate for the P-glycoprotein efflux drug transporter in colorectal mucosa. Equivalent studies in the cervicovaginal epithelium have not been reported. Here, we describe the development of a physiologically relevant model to investigate the permeability of antiretroviral drugs across the vaginal epithelium. Barrier properties of the HEC-1A human endometrial epithelial cell line were determined, in a dual chamber model, by measurement of transepithelial electrical resistance, immunofluorescent staining of tight junctions and bi-directional paracellular permeability of mannitol. We then applied this model to investigate the permeability of tenofovir, darunavir and dapivirine. Efflux ratios indicated that the permeability of each drug was transporter-independent in this model. Reduction of pH to physiological levels in the apical compartment increased absorptive transfer of darunavir, an effect that was reversed by inhibition of MRP efflux transport via MK571. Thus, low pH may increase the transfer of darunavir across the epithelial barrier via increased MRP transporter activity. In a previous in vivo study in the macaque model, we demonstrated increased MRP2 expression following intravaginal stimulation with darunavir which may further increase drug uptake. Stimulation with inflammatory modulators had no effect on drug permeability across HEC-1A barrier epithelium but, in the VK2/E6E7 vaginal cell line, increased expression of both efflux and uptake drug transporters which may influence darunavir disposition.

Modulatory Mechanisms of Pathogenicity in Porphyromonas gingivalis and Other Periodontal Pathobionts.

The pathogenesis of periodontitis depends on a sustained feedback loop where bacterial virulence factors and immune responses both contribute to inflammation and tissue degradation. Periodontitis is a multifactorial disease that is associated with a pathogenic shift in the oral microbiome. Within this shift, low-abundance Gram-negative anaerobic pathobionts transition from harmless colonisers of the subgingival environment to a virulent state that drives evasion and subversion of innate and adaptive immune responses. This, in turn, drives the progression of inflammatory disease and the destruction of tooth-supporting structures. From an evolutionary perspective, bacteria have developed this phenotypic plasticity in order to respond and adapt to environmental stimuli or external stressors. This review summarises the available knowledge of genetic, transcriptional, and post-translational mechanisms which mediate the commensal-pathogen transition of periodontal bacteria. The review will focus primarily on Porphyromonas gingivalis.

Serum antibody response against periodontal bacteria and coronary heart disease: Systematic review and meta-analysis.

AIM: The present systematic review and meta-analysis assessed the strength of a reported association between elevated serum anti-periodontal bacterial antibody responses and coronary heart disease (CHD). MATERIALS AND METHODS: Twenty original studies were identified after systematically searching five databases. The majority (n = 11) compared serum anti-Porphyromonas gingivalis (Pg) and/or anti-Aggregatibacter actinomycetemcomitans (Aa) IgG antibody responses between CHD patients and control participants. The strength of the association between serum anti-Pg antibodies and CHD (n = 10) and serum anti-Aa antibodies and CHD (n = 6) was investigated using a meta-analysis approach separately. RESULTS: Most studies (61%) reported that the serum IgG antibody responses were elevated in CHD patients than in controls. The meta-analyses showed a significant association between elevated serum IgG antibody responses (anti-Pg and anti-Aa) and CHD, with pooled odds ratios of 1.23 [95% confidence interval (CI): 1.09-1.38, p = .001] and 1.25 (95% CI: 1.04-1.47, p = .0004), respectively. CONCLUSIONS: A modest increase of CHD events in individuals with higher serum anti-Pg and anti-Aa IgG antibody responses may support their use as potential biomarkers to detect and monitor at-risk populations. However, the observed inconsistencies with the design and interpretation of immunoassays warrant standardization of the immunoassays assessing antibody responses against periodontal bacteria.

Antimicrobial Synergy Testing: Comparing the Tobramycin and Ceftazidime Gradient Diffusion Methodology Used in Assessing Synergy in Cystic Fibrosis-Derived Multidrug-Resistant Pseudomonas aeruginosa.

The need for synergy testing is driven by the necessity to extend the antimicrobial spectrum, reducing drug dosage/toxicity and the development of resistance. Despite the abundance of synergy testing methods, there is the absence of a gold standard and a lack of synergy correlation among methods. The most popular method (checkerboard) is labor-intensive and is not practical for clinical use. Most clinical laboratories use several gradient synergy methods which are quicker/easier to use. This study sought to evaluate three gradient synergy methods (direct overlay, cross, MIC:MIC ratio) with the checkerboard, and compare two interpretative criteria (the fractional inhibitory concentration index (FICI) and susceptibility breakpoint index (SBPI)) regarding these methods. We tested 70 multidrug-resistant Pseudomonas aeruginosa, using a tobramycin and ceftazidime combination. The agreement between the checkerboard and gradient methods was 60 to 77% for FICI, while agreements for SBPI that ranged between 67 and 82.86% were statistically significant (p ≤ 0.001). High kappa agreements were observed using SBPI (Ƙ > 0.356) compared to FICI (Ƙ < 0.291) criteria, and the MIC:MIC method demonstrated the highest, albeit moderate, intraclass correlation coefficient (ICC = 0.542) estimate. Isolate resistance profiles suggest method-dependent synergism for isolates, with ceftazidime susceptibility after increased exposure. The results show that when interpretative criteria are considered, gradient diffusion (especially MIC:MIC) is a valuable and practical method that can inform the treatment of cystic fibrosis patients who are chronically infected with P. aeruginosa.

Clonal evolution of Candida albicans, Candida glabrata and Candida dubliniensis at oral niche level in health and disease.

Background: Candida species have long been recognised as aetiological agents of opportunistic infections of the oral mucosa, and more recently, as players of polymicrobial interactions driving caries, periodontitis and oral carcinogenesis. Methods: We studied the clonal structure of Candida spp. at oral niche resolution in patients (n = 20) with a range of oral health profiles over 22 months. Colonies from oral micro-environments were examined with multilocus sequencing typing. Results: Candida spp. identified were C. albicans, C. glabrata and C. dubliniensis. Increased propensity for micro-variations giving rise to multiple diploid strain types (DST), as a result of loss of heterozygosity, was observed among C. albicans clade 1 isolates compared to other clades. Micro-variations among isolates were also observed in C. dubliniensis contra to expectations of stable population structures for this species. Multiple sequence types were retrieved from patients without clinical evidence of oral candidosis, while single sequence types were isolated from oral candidosis patients. Conclusion: This is the first study to describe the clonal population structure, persistence and stability of Candida spp. at oral niche level. Future research investigating links between Candida spp. clonality and oral disease should recognise the propensity to micro-variations amongst oral niches in C. albicans and C. dubliniensis identified here.

Trends of Antimicrobial Resistance and Combination Susceptibility Testing of Multidrug-Resistant Pseudomonas aeruginosa Isolates from Cystic Fibrosis Patients: a 10-Year Update.

Antimicrobial combination therapy is a time/resource-intensive procedure commonly employed in the treatment of cystic fibrosis (CF) pulmonary exacerbations caused by Pseudomonas aeruginosa Ten years ago, the most promising antimicrobial combinations were proposed, but there has since been the introduction of new ß-lactam plus ß-lactamase inhibitor antimicrobial combinations. The aims of this study were to (i) compare in vitro activity of these new antimicrobials with other antipseudomonal agents and suggest their most synergistic antimicrobial combinations and (ii) determine antimicrobial resistance rates and study inherent trends of antimicrobials over 10 years. A total of 721 multidrug-resistant P. aeruginosa isolates from 183 patients were collated over the study period. Antimicrobial susceptibility and combination testing were carried out using the Etest method. The results were further assessed using the fractional inhibitory concentration index (FICI) and the susceptible breakpoint index (SBPI). Resistance to almost all antimicrobial agents maintained a similar level during the studied period. Colistin (P < 0.001) and tobramycin (P = 0.001) were the only antimicrobials with significant increasing isolate susceptibility, while an increasing resistance trend was observed for levofloxacin. The most active antimicrobials were colistin, ceftolozane-tazobactam, ceftazidime-avibactam, and gentamicin. All combinations with ß-lactam plus ß-lactamase inhibitors produced some synergistic results. Ciprofloxacin plus ceftolozane-tazobactam (40%) and amikacin plus ceftazidime (36.7%) were the most synergistic combinations, while colistin combinations gave the best median SBPI (50.11). This study suggests that effective fluoroquinolone stewardship should be employed for CF patients. It also presents in vitro data to support the efficacy of novel combinations for use in the treatment of chronic P. aeruginosa infections.

Detection of periodontal microorganisms in coronary atheromatous plaque specimens of myocardial infarction patients: A systematic review and meta-analysis.

BACKGROUND: Microbial translocation from inflamed periodontal pockets into coronary atheroma via systemic circulation is one of the proposed pathways that links periodontitis and myocardial infarction (MI). The purpose of this systematic review is to determine the reported prevalence of periodontal microorganisms in coronary atheroma and/or aspirated clot samples collected from MI patients with periodontal disease. METHODOLOGY: The "Preferred Reporting Items for Systematic Reviews and Meta-Analyses" (PRISMA) guidelines were followed. Six databases were systematically searched using Medical Subject Headings/Index and Entree terms. After a thorough screening, fourteen publications spanning over ten years (2007-2017) were eligible for this systematic review and meta-analysis. RESULTS: Out of 14 included studies, 12 reported presence of periodontal bacterial DNA in coronary atherosclerotic plaque specimens. Overall, Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans were the most frequently detected periodontal bacterial species. Meta-analysis revealed that the prevalence of P. gingivalis was significantly higher than A. actinomycetemcomitans in coronary atheromatous plaque samples. Apart from periodontal microbes, DNA from a variety of other microbes e.g. Pseudomonas fluorescens, Streptococcus species, Chlamydia pneumoniae were also recovered from the collected samples. CONCLUSION: Consistent detection of periodontal bacterial DNA in coronary atheroma suggests their systemic dissemination from periodontal sites. It should further be investigated whether they are merely bystanders or induce any structural changes within coronary arterial walls.

The oral health status of patients with peripheral vascular disorders: A systematic review.

OBJECTIVES: Periodontal disease and tooth loss were found to be associated with several peripheral vascular disorders. Nonetheless, an evaluation of the literature on the broader domains of oral health in individuals with peripheral vascular disorders is lacking. This systematic review aims to collate the current evidence on the oral health status of individuals with peripheral vascular disorders. METHODS: Five electronic databases were searched for studies assessing oral health parameters in individuals with peripheral vascular disorders. Outcome measures considered were periodontal health, dentition status, caries indices, oral prostheses, oral pathologies and oral hygiene behaviours. The Newcastle-Ottawa scale was used to appraise the quality of the studies. RESULTS: From 3025 records identified, 24 studies involving 1232 participants with peripheral vascular disorders were included in this review. In nine studies, periodontitis was significantly more prevalent in peripheral vascular disorders compared to non-peripheral vascular disorders participants. A further six studies reported individuals with peripheral vascular disorders also had significantly fewer teeth and increased rates of edentulism. Only one study reported a higher incidence of dental caries in peripheral vascular disorders participants. Other aspects of oral health such as oral prosthesis, oral pathology and oral hygiene behaviours were seldom assessed. CONCLUSIONS: The scarcity of studies reporting on broader domains limited our ability to arrive at a conclusion regarding the oral health status of individuals with peripheral vascular disorders. Future studies ought to assess these domains in individuals with peripheral vascular disorders and controls to gain a more complete understanding of oral health and its potential association with peripheral vascular disorders.

Longitudinal Surveillance and Combination Antimicrobial Susceptibility Testing of Multidrug-Resistant Achromobacter Species from Cystic Fibrosis Patients.

Achromobacter spp. are recognized as emerging pathogens in patients with cystic fibrosis (CF). Though recent works have established species-level identification using nrdA sequencing, there is a dearth in knowledge relating to species-level antimicrobial susceptibility patterns and antimicrobial combinations, which hampers the use of optimal antimicrobial combinations for the treatment of chronic infections. The aims of this study were to (i) identify at species-level referred Achromobacter isolates, (ii) describe species-level antimicrobial susceptibility profiles, and (iii) determine the most promising antimicrobial combination for chronic Achromobacter infections. A total of 112 multidrug-resistant (MDR) Achromobacter species isolates from 39 patients were identified using nrdA sequencing. Antimicrobial susceptibility and combination testing were carried out using the Etest method. We detected six species of Achromobacter and found that Achromobacter xylosoxidans was the most prevalent species. Interestingly, sequence analysis showed it was responsible for persistent infection (18/28 patients), followed by Achromobacter ruhlandii (2/3 patients). Piperacillin-tazobactam (70.27%) and co-trimoxazole (69.72%) were the most active antimicrobials. Differences were observed in species-level susceptibility to ceftazidime, carbapenems, ticarcillin-clavulanate, and tetracycline. Antimicrobial combinations with co-trimoxazole or tobramycin demonstrate the best synergy, while co-trimoxazole gave the best susceptibility breakpoint index values. This study enriches the understanding of MDR Achromobacter spp. epidemiology and confirms prevalence and chronic colonization of A. xylosoxidans in CF lungs. It presents in vitro data to support the efficacy of new combinations for use in the treatment of chronic Achromobacter infections.

Oral bacterial diversity is inversely correlated with mucosal inflammation.

OBJECTIVE: We investigated the relationship amongst the oral mucosal bacterial community, clinical severity and inflammatory markers in the two most common immune-mediated oral mucosal diseases, namely recurrent aphthous stomatitis (RAS) and oral lichen planus (LP). METHODS: Patients with RAS (n = 15) and LP (n = 18) and healthy controls (n = 13) were recruited using criteria to reduce the effect of factors that influence the microbiota structure independently of oral mucosal disease. Clinical severity was quantified using validated scoring methods. DNA was extracted from oral mucosal swabs for 16S rRNA gene high-throughput sequencing. Salivary cytokines were measured using cytometric bead assays. Correlation studies were conducted amongst microbial diversity, clinical scores and cytokine concentrations. RESULTS: We observed a significant reduction of bacterial diversity in LP and RAS patients compared to controls (p = .021 and .044, respectively). Reduced bacterial diversity in LP and RAS correlated with increased clinical scores of the two conditions (⍴ = -0.551 to -0.714). A negative correlation was observed between microbial diversity and salivary interferon-γ, interleukin-17A and interleukin-1ß (⍴ = -0.325 to -0.449). CONCLUSIONS: This study reports reduced oral microbial diversity in the context of increased mucosal inflammation and supports the role for microbial diversity as a marker or contributor to oral mucosal inflammatory disease activity and development.

Genomic Stability of Composite SCCmec ACME and COMER-Like Genetic Elements in Staphylococcus epidermidis Correlates With Rate of Excision.

The epidemiological success of methicillin-resistant Staphylococcus aureus USA300 has been associated with the presence of two mobile elements, the arginine catabolic mobile element (ACME) and the copper and mercury resistance (COMER) element. These two mobile elements are associated with resistance to copper, which has been related to host fitness and survival within macrophages. Several studies found that ACME is more prevalent, and exhibits greater diversity, in Staphylococcus epidermidis while COMER has not been identified in S. epidermidis or any other staphylococcal species. We aimed in this study to evaluate the presence and diversity of ACME and COMER-like elements in our S. epidermidis clinical isolates. The genomes of 58 S. epidermidis clinical isolates, collected between 2009 and 2018 in a Scottish hospital, were sequenced. A core-genome phylogenetic tree and genome based MLST typing showed that more than half of the isolates belong to the clinically predominant sequence type2 (ST2) and these isolates have been found to split into two lineages within the phylogenetic tree. Analysis showed the presence of SCCmec in the majority of isolates. Comparative analysis identified a cluster of ACME-positive isolates with most of them belonging to ST48. ACME showed high variation even between isolates of the same ACME type and ST. COMER-like elements have been identified in one of the two major hospital adapted drug resistant ST2 lineages; and showed high stability. This difference in stability at the genomic level correlates well with the up to one hundred times higher excision frequency found for the SCCmec elements in ACME-containing isolates compared to COMER-like element containing isolates. ACME/COMER-like element positive isolates did not show a significant phenotype of decreased copper susceptibility, while resistance to mercury was over-represented in COMER-like element positive isolates. To the best of our knowledge, this is the first molecular characterization of COMER-like elements in S. epidermidis isolates. The presence of the COMER-like elements is the most prominent accessory genome feature of these successful lineages suggesting that this chromosomal island contributes to the success and wide clinical distribution of ST2 S. epidermidis.

In Vivo Modulation of Cervicovaginal Drug Transporters and Tissue Distribution by Film-Released Tenofovir and Darunavir for Topical Prevention of HIV-1.

Clinical trials have demonstrated partial protection against HIV-1 infection by vaginal microbicide formulations based on antiretroviral (ARV) drugs. Improved formulations that will maintain sustained drug concentrations at viral target sites in the cervicovaginal mucosa are needed. We have previously demonstrated that treatment of cervicovaginal cell lines with ARV drugs can alter gene expression of drug transporters, suggesting that the mucosal disposition of ARV drugs delivered vaginally can be modulated by drug transporters. This study aimed to investigate in vivo modulation of drug transporter expression in a nonhuman primate model by tenofovir and darunavir released from film formulations. Cervicovaginal tissues were collected from drug-naïve macaques and from macaques vaginally treated with film formulations of tenofovir or darunavir. Drug release in vaginal fluid as well as drug absorption in cervicovaginal tissues and lymph nodes were verified by mass spectrometry. The effects of exposure to drugs on the expression of transporters relevant to ARV drugs were evaluated by quantitative PCR. We showed expression in cervicovaginal tissue of drug-naïve macaques of transporters important for distribution of ARV drugs, albeit at lower levels compared to human tissue for key transporters including P-glycoprotein. Concentrations of tenofovir and darunavir well above the EC50 values determined in vitro were detected in vaginal fluid and vaginal tissues of macaques treated with drug-dissolving films over 24 h and were also comparable to those shown previously to modulate drug transporter expression. Accordingly, Multidrug Resistance associated Protein 2 (MRP2) in cervicovaginal tissue was upregulated by both tenofovir and darunavir. The two drugs also differentially induced and/or inhibited expression of key uptake transporters for reverse transcriptase inhibitors and protease inhibitors. The lower expression of key transporters in macaques may result in increased retention of ARV drugs at the simian cervicovaginal mucosa compared to the human mucosa and has implications for translation of preclinical data. Modulation of drug transporter expression by tenofovir and darunavir points to the potential benefit of MRP2 inhibition to increase ARV drug penetration through the cervicovaginal epithelium.

Challenges and opportunities for antimicrobial stewardship in resource-rich and resource-limited countries.

Introduction: Inappropriate prescription practices, patient and provider knowledge and attitudes, variable availability of diagnostic and surveillance systems, and the unrestricted use of antimicrobials in animals and plants are contributory factors to the global crisis of antimicrobial resistance (AMR). Areas covered: Notwithstanding that interventions to revert AMR should be tailored to the socio-politico-economic landscape, there is a global consensus for the implementation and enhancement of antimicrobial stewardship strategies. Yet the implementation of Antimicrobial Stewardship Programs (ASPs) remains relatively limited within healthcare settings and faces complex challenges in resource-limited countries. The current review summarizes the limitations of current ASPs, translation challenges in resource-limited countries, and potential solutions. Expert opinion: Suboptimal ASP implementation in hospitals is multifactorial. Restriction of antimicrobial use should be informed by risk-benefit analyses, including the potential for substitute prescribing, and displacement of selection pressures. Thresholds in population use of antibiotics above which AMR increases may provide quantitative targets for ASPs. Horizontal and vertical collaborations involving policymakers and the general public are of paramount importance. While impactful prescribing changes require sustained engagement of the public and health-care professionals, we warn against over-estimating the benefits of behavioral interventions. We advocate for population-level stewardship interventions in addition to investment in structural factors that will aid ASP implementation.