Evolution of Resistance against Ciprofloxacin, Tobramycin, and Trimethoprim/Sulfamethoxazole in the Environmental Opportunistic Pathogen Stenotrophomonas maltophilia.

Stenotrophomonas maltophilia is an opportunistic pathogen that produces respiratory infections in immunosuppressed and cystic fibrosis patients. The therapeutic options to treat S. maltophilia infections are limited since it exhibits resistance to a wide variety of antibiotics such as ß-lactams, aminoglycosides, tetracyclines, cephalosporins, macrolides, fluoroquinolones, or carbapenems. The antibiotic combination trimethoprim/sulfamethoxazole (SXT) is the treatment of choice to combat infections caused by S. maltophilia, while ceftazidime, ciprofloxacin, or tobramycin are used in most SXT-resistant infections. In the current study, experimental evolution and whole-genome sequencing (WGS) were used to examine the evolutionary trajectories of S. maltophilia towards resistance against tobramycin, ciprofloxacin, and SXT. The genetic changes underlying antibiotic resistance, as well as the evolutionary trajectories toward that resistance, were determined. Our results determine that genomic changes in the efflux pump regulatory genes smeT and soxR are essential to confer resistance to ciprofloxacin, and the mutation in the rplA gene is significant in the resistance to tobramycin. We identified mutations in folP and the efflux pump regulator smeRV as the basis of SXT resistance. Detailed and reliable knowledge of ciprofloxacin, tobramycin, and SXT resistance is essential for safe and effective use in clinical settings. Herein, we were able to prove once again the extraordinary ability that S. maltophilia has to acquire resistance and the importance of looking for alternatives to combat this resistance.

Effectiveness of an intervention to improve ART adherence among men who have sex with men living with HIV: a randomized controlled trial in three public HIV clinics in Mexico.

We conducted a parallel-group randomized controlled trial in three HIV clinics in Mexico to evaluate a user-centred habit-formation intervention to improve ART adherence among MSM living with HIV. We randomized 74 participants to the intervention group and 77 to the control group. We measured adherence at one, four, and ten months through medication possession ratio and self-reported adherence. Additionally, we measured viral load, CD4 cell count, major depression disorder symptoms, and alcohol and substance use disorder at baseline, fourth and tenth months. We found no statistically significant effect on adherence between groups. However, the intervention demonstrated positive results in major depression disorder symptoms (21% vs. 6%, p = 0.008) and substance use disorder (11% vs. 1%, p = 0.018) in the fourth month. The latter is relevant because, in addition to its direct benefit, it might also improve the chances of maintaining adequate adherence in the long term. This trial was retrospectively registered at ClinicalTrials.gov (trial number NCT03410680) on 8 January 2018.Trial registration: ClinicalTrials.gov identifier: NCT03410680.

The Cost of Providing Comprehensive HIV Services to Key Populations: An Analysis of the LINKAGES Program in Kenya and Malawi.

INTRODUCTION: Timely data on HIV service costs are critical for estimating resource needs and allocating funding, but few data exist on the cost of HIV services for key populations (KPs) at higher risk of HIV infection in low- and middle-income countries. We aimed to estimate the total and per contact annual cost of providing comprehensive HIV services to KPs to inform planning and budgeting decisions. METHODS: We collected cost data from the Linkages across the Continuum of HIV Services for Key Populations Affected by HIV (LINKAGES) program in Kenya and Malawi serving female and male sex workers, men who have sex with men, and transgender women. Data were collected prospectively for fiscal year (FY) 2019 and retrospectively for start-up activities conducted in FY2015 and FY2016. Data to estimate economic costs from the provider's perspective were collected from LINKAGES headquarters, country offices, implementing partners (IPs), and drop-in centers (DICs). We used top-down and bottom-up cost estimation approaches. RESULTS: Total economic costs for FY2019 were US$6,175,960 in Kenya and US$4,261,207 in Malawi. The proportion of costs incurred in IPs and DICs was 66% in Kenya and 42% in Malawi. The costliest program areas were clinical services, management, peer outreach, and monitoring and data use. Mean cost per contact was US$127 in Kenya and US$279 in Malawi, with a mean cost per contact in DICs and IPs of US$63 in Kenya and US$104 in Malawi. CONCLUSION: Actions undertaken above the service level in headquarters and country offices along with those conducted below the service level in communities, comprised important proportions of KP HIV service costs. The costs of pre-service population mapping and size estimation activities were not negligible. Costing studies that focus on the service level alone are likely to underestimate the costs of delivering HIV services to KPs.

Efflux in Gram-negative bacteria: what are the latest opportunities for drug discovery?

INTRODUCTION: The resistance-nodulation-division (RND) family is the most important group of multidrug efflux pumps in Gram-negative bacteria. Their inhibition increases the susceptibility of these microorganisms to antibiotics. The study of the effect of efflux pumps' overexpression on bacterial physiology in antibiotic-resistant mutants allows for the identification of exploitable weaknesses associated with resistance acquisition. AREAS COVERED: The authors describe different RND multidrug efflux pumps' inhibition strategies and provide examples of inhibitors. This review also discusses inducers of the expression of efflux pumps, used in human therapy that can produce transient resistance to antibiotics in vivo. Since RND efflux pumps may have a role in bacterial virulence, the use of these systems as targets in the search of antivirulence compounds is also discussed. Finally, this review analyzes how the study of trade-offs associated with resistance acquisition mediated by efflux pumps' overexpression may guide strategies to tackle such resistance. EXPERT OPINION: Increasing the knowledge of the regulation, structure and function of efflux pumps provides information for the rational design of RND efflux pump inhibitors. These inhibitors would increase bacterial susceptibility to several antibiotics and, occasionally, will reduce bacterial virulence. Furthermore, the information on the effect that efflux pumps' overexpression has on bacterial physiology may serve to develop new anti-resistance strategies.

Translating eco-evolutionary biology into therapy to tackle antibiotic resistance.

Antibiotic resistance is currently one of the most important public health problems. The golden age of antibiotic discovery ended decades ago, and new approaches are urgently needed. Therefore, preserving the efficacy of the antibiotics currently in use and developing compounds and strategies that specifically target antibiotic-resistant pathogens is critical. The identification of robust trends of antibiotic resistance evolution and of its associated trade-offs, such as collateral sensitivity or fitness costs, is invaluable for the design of rational evolution-based, ecology-based treatment approaches. In this Review, we discuss these evolutionary trade-offs and how such knowledge can aid in informing combination or alternating antibiotic therapies against bacterial infections. In addition, we discuss how targeting bacterial metabolism can enhance drug activity and impair antibiotic resistance evolution. Finally, we explore how an improved understanding of the original physiological function of antibiotic resistance determinants, which have evolved to reach clinical resistance after a process of historical contingency, may help to tackle antibiotic resistance.

Coordinación y cooperación de las redes formadas detrás del continuo de atención a personas que viven con VIH en México.

OBJETIVO: Describir y caracterizar las redes formadas detrás del continuo de atención a personas que viven con VIH en México. Material y métodos. Bajo un enfoque de análisis de redes sociales se analizó información sobre las relaciones que establecen los actores que participan en el continuo de atención del VIH. RESULTADOS: Existe una formación de re-des de atención con distintos actores y, conforme se avanza en el continuo de atención, las redes tienden a fragmentarse y se observa una baja conectividad. CONCLUSIONES: La provisión de servicios para VIH en México es un proceso de gober-nanza múltiple; sin embargo, la configuración de las redes no implica que la provisión de servicios sea óptima. No obstante, la formación de redes es una potencial herramienta que los Centros Ambulatorios para la Prevención y Atención de Sida e Infecciones de Transmisión Sexual y Servicios de Atención Integral Hospitalaria han establecido para lograr su objetivo de ofrecer atención oportuna y continua, ante un contexto de recursos limitados y de gestión pública por resultados.

Wildlife and Antibiotic Resistance.

Antibiotic resistance is a major human health problem. While health care facilities are main contributors to the emergence, evolution and spread of antibiotic resistance, other ecosystems are involved in such dissemination. Wastewater, farm animals and pets have been considered important contributors to the development of antibiotic resistance. Herein, we review the impact of wildlife in such problem. Current evidence supports that the presence of antibiotic resistance genes and/or antibiotic resistant bacteria in wild animals is a sign of anthropic pollution more than of selection of resistance. However, once antibiotic resistance is present in the wild, wildlife can contribute to its transmission across different ecosystems. Further, the finding that antibiotic resistance genes, currently causing problems at hospitals, might spread through horizontal gene transfer among the bacteria present in the microbiomes of ubiquitous animals as cockroaches, fleas or rats, supports the possibility that these organisms might be bioreactors for the horizontal transfer of antibiotic resistance genes among human pathogens. The contribution of wildlife in the spread of antibiotic resistance among different hosts and ecosystems occurs at two levels. Firstly, in the case of non-migrating animals, the transfer will take place locally; a One Health problem. Paradigmatic examples are the above mentioned animals that cohabit with humans and can be reservoirs and vehicles for antibiotic resistance dissemination. Secondly, migrating animals, such as gulls, fishes or turtles may participate in the dissemination of antibiotic resistance across different geographic areas, even between different continents, which constitutes a Global Health issue.

Antibiotic resistance: Time of synthesis in a post-genomic age.

Antibiotic resistance has been highlighted by international organizations, including World Health Organization, World Bank and United Nations, as one of the most relevant global health problems. Classical approaches to study this problem have focused in infected humans, mainly at hospitals. Nevertheless, antibiotic resistance can expand through different ecosystems and geographical allocations, hence constituting a One-Health, Global-Health problem, requiring specific integrative analytic tools. Antibiotic resistance evolution and transmission are multilayer, hierarchically organized processes with several elements (from genes to the whole microbiome) involved. However, their study has been traditionally gene-centric, each element independently studied. The development of robust-economically affordable whole genome sequencing approaches, as well as other -omic techniques as transcriptomics and proteomics, is changing this panorama. These technologies allow the description of a system, either a cell or a microbiome as a whole, overcoming the problems associated with gene-centric approaches. We are currently at the time of combining the information derived from -omic studies to have a more holistic view of the evolution and spread of antibiotic resistance. This synthesis process requires the accurate integration of -omic information into computational models that serve to analyse the causes and the consequences of acquiring AR, fed by curated databases capable of identifying the elements involved in the acquisition of resistance. In this review, we analyse the capacities and drawbacks of the tools that are currently in use for the global analysis of AR, aiming to identify the more useful targets for effective corrective interventions.

The Antibiotic Fosfomycin Mimics the Effects of the Intermediate Metabolites Phosphoenolpyruvate and Glyceraldehyde-3-Phosphate on the Stenotrophomonas maltophilia Transcriptome.

Stenotrophomonas maltophilia is an opportunistic pathogen with an environmental origin, which presents a characteristically low susceptibility to antibiotics and is capable of acquiring increased levels of resistance to antimicrobials. Among these, fosfomycin resistance seems particularly intriguing; resistance to this antibiotic is generally due to the activity of fosfomycin-inactivating enzymes, or to defects in the expression or the activity of fosfomycin transporters. In contrast, we previously described that the cause of fosfomycin resistance in S. maltophilia was the inactivation of enzymes belonging to its central carbon metabolism. To go one step further, here we studied the effects of fosfomycin on the transcriptome of S. maltophilia compared to those of phosphoenolpyruvate-its structural homolog-and glyceraldehyde-3-phosphate-an intermediate metabolite of the mutated route in fosfomycin-resistant mutants. Our results show that transcriptomic changes present a large degree of overlap, including the activation of the cell-wall-stress stimulon. These results indicate that fosfomycin activity and resistance are interlinked with bacterial metabolism. Furthermore, we found that the studied compounds inhibit the expression of the smeYZ efflux pump, which confers intrinsic resistance to aminoglycosides. This is the first description of efflux pump inhibitors that can be used as antibiotic adjuvants to counteract antibiotic resistance in S. maltophilia.

Complete Genome Sequencing of Stenotrophomonas acidaminiphila ZAC14D2_NAIMI4_2, a Multidrug-Resistant Strain Isolated from Sediments of a Polluted River in Mexico, Uncovers New Antibiotic Resistance Genes and a Novel Class-II Lasso Peptide Biosynthesis Gene Cluster.

Here, we report the first complete genome sequence of a Stenotrophomonas acidaminiphila strain, generated with PacBio RS II single-molecule real-time technology, consisting of a single circular chromosome of 4.13 Mb. We annotated mobile genetic elements and natural product biosynthesis clusters, including a novel class-II lasso peptide with a 7-residue macrolactam ring.