Search

Optotracers have a wide-range of applications in the detection, visualization, and characterization of biofilms. More recently, optotracers have been used in antibiotic susceptibility assays for biofilms and for the detection of biomarkers in clinical biofilm infections. This is particularly important, given that the field is increasingly focused on the evaluation of novel anti-biofilm agents and the study of biofilms in host-relevant systems. Given this, the possibility of using optotracers for an expanded set of biofilm focus areas is important to explore. In this study, we examine the application of the optotracer EbbaBiolight 680 to study biofilms in a host-relevant system and for the evaluation of a non-conventional anti-biofilm remedy. UsingStaphylococcus aureuswound biofilms as a case study, we leverage a previously builtin vitro4-D wound microenvironment platform and a plant-based wound remedy. We find that EbbaBiolight 680 can be used to visualizeS. aureusbiofilms, likely detecting both bacterial cells and bacterial EPS components. Further, the optotracer can be used to evaluate and quantify the effects of the plant-based wound remedy onS. aureusbiomass formation. However, in the 4-D wound microenvironment, EbbaBiolight 680 detected host cellular and matrix elements, which confounded the detection of biofilms. Taken together, this study opens the possibility of using optotracers as screening tools for the identification of novel anti-biofilm treatments and underscores the need for modifications for their use in host-relevant systems.

Given their future roles as citizens and decision makers, science outreach focused on children is important and relevant. We describe a scientist-led outreach platform (Talk To A Scientist), that uses a webinar-based approach to discuss a range of science topics with children (6-16 years). Based in India and led by two working scientists, Talk To A Scientist has been running for nearly 3 years, with a large and diverse reach across school students. In addition to webinars, the platform regularly hosts archived video content and weekly science activities, along with occasional summer family quizzes and age-specific webinars. We outline the framework used to build Talk To A Scientist, and discuss key considerations and challenges in the development and expansion of the program. We believe that the Talk To A Scientist outreach model focused on children can serve as a guideline for the implementation of similar platforms across diverse settings, and is amenable to a range of modifications to enhance engagement, sustain interest, and tailor outreach to specific groups.

Bacterial biofilms are a major cause of delayed wound healing. Consequently, the study of wound biofilms, particularly in host-relevant conditions, has gained importance. Most in vitro studies employ refined laboratory media to study biofilms, representing conditions that are not relevant to the infection state. To mimic the wound milieu, in vitro biofilm studies often incorporate serum or plasma in growth conditions, or employ clot or matrix-based biofilm models. While incorporating serum or plasma alone is a minimalistic approach, the more complex in vitro wound models are technically demanding, and poorly compatible with standard biofilm assays. Based on previous reports of clinical wound fluid composition, we have developed an in vitro wound milieu (IVWM) that includes, in addition to serum (to recapitulate wound fluid), matrix elements and biochemical factors. With Luria-Bertani broth and Fetal Bovine Serum (FBS) for comparison, the IVWM was used to study planktonic growth, biofilm features, and interspecies interactions, of common wound pathogens, Staphylococcus aureus and Pseudomonas aeruginosa. We demonstrate that the IVWM recapitulates widely reported in vivo biofilm features such as biomass formation, metabolic activity, increased antibiotic tolerance, 3D structure, and interspecies interactions for monospecies and mixed-species biofilms. Further, the IVWM is simple to formulate, uses laboratory-grade components, and is compatible with standard biofilm assays. Given this, it holds potential as a tractable approach to study wound biofilms under host-relevant conditions.

Antibiotic resistance is a public health threat, and the rise of multidrug-resistant bacteria, including those that form protective biofilms, further compounds this challenge. Antimicrobial peptides (AMPs) have been recognized for their anti-infective properties, including their ability to target processes important for biofilm formation. However, given the vast array of natural and synthetic AMPs, determining potential candidates for anti-biofilm testing is a significant challenge. In this study, we present an in silico approach, based on open-source tools, to identify AMPs with potential anti-biofilm activity. This approach is developed using the sortase-pilin machinery, important for adhesion and biofilm formation, of the multidrug-resistant, biofilm-forming pathogen C. striatum as the target. Using homology modeling, we modeled the structure of the C. striatum sortase C protein, resembling the semi-open lid conformation adopted during pilus biogenesis. Next, we developed a structural library of 5544 natural and synthetic AMPs from sequences in the DRAMP database. From this library, AMPs with known anti-Gram positive activity were filtered, and 100 select AMPs were evaluated for their ability to interact with the sortase C protein using in-silico molecular docking. Based on interacting residues and docking scores, we built a preference scale to categorize candidate AMPs in order of priority for future in vitro and in vivo biofilm studies. The considerations and challenges of our approach, and the resources developed, which includes a search-enabled repository of predicted AMP structures and protein-peptide interaction models relevant to biofilm studies (B-AMP), can be leveraged for similar investigations across other biofilm targets and biofilm-forming pathogens.

Biofilms are the major way of life for both bacteria and fungi [...]

Bacterial biofilms are a major cause of delayed wound healing. Consequently, the study of wound biofilms, particularly in host-relevant conditions, has gained importance. Most in vitro biofilm studies employ refined laboratory media to study biofilms, conditions that are not relevant to the infection state. To mimic the wound milieu, in vitro biofilm studies often incorporate serum or plasma in growth conditions, or employ clot or matrix-based biofilm models. While incorporating serum or plasma alone is a minimalistic approach, the more complex in vitro wound models are technically demanding, and poorly compatible with standard biofilm assays. Based on previous reports of clinical wound fluid composition, we have developed an in vitro wound milieu (IVWM) that includes, in addition to serum (to recapitulate wound fluid), matrix elements and biochemical factors. In comparison with Luria-Bertani broth and Fetal Bovine Serum (FBS), the IVWM was used to study planktonic growth and biofilm features, including interspecies interactions, of common wound pathogens, Staphylococcus aureus and Pseudomonas aeruginosa. We demonstrate that the IVWM recapitulates widely reported in vivo biofilm features such as metabolic activity, increased antibiotic tolerance, 3D structure, and interspecies interactions for single- and co-species biofilms. Further, the IVWM is simple to formulate, uses laboratory-grade components, and is compatible with standard biofilm assays. Given this, it holds potential as a tractable approach to study wound biofilms under host-relevant conditions.

Traditional plant-based remedies hold vast potential as novel antimicrobial agents, particularly for recalcitrant infection states such as biofilms. To explore their potential, it is important to bring these remedies out of historical treatises, and into present-day scientific evaluation. Using an example of Indian traditional medicine (Ayurveda), we present a perspective toward evaluating historical remedies for anti-biofilm potential. Across compendia, we identified three plant-based remedies (of Kalanchoe pinnata, Cynodon dactylon, and Ocimum tenuiflorum) recommended for wounds. The remedies were reconstituted in accordance with historical practices, and tested for their effects on biofilm formation and eradication assays of wound pathogens, Pseudomonas aeruginosa and Staphylococcus aureus. Based on our approach and the results obtained, we provide insights into the considerations and challenges related to identifying potential remedies in historical texts, and testing them in the laboratory with standard biofilm assays. We believe this will be relevant for future studies exploring anti-biofilm approaches at the interface of historical medicine and present-day scientific practices.

A wide range of microbes inhabit the oral cavity, and bacterial and fungal communities most often exist as structured communities or biofilms. The use of tobacco alters the structure of the oral microbiome, including that of potentially malignant lesions, and the altered oral microbiome influences key microenvironmental changes such as chronic inflammation, secretion of carcinogenic toxins, cellular and tissue remodelling and suppression of apoptosis. Given this, it is clear that the bacterial and fungal biofilms in potentially malignant states are likely not passive entities, but could play a critical role in shaping potential malignant and carcinogenic conditions. This holds potential towards leveraging the oral microbiome for the management of tobacco-associated potentially malignant lesions and oral cancer. Here, we explore this line of investigation by reviewing the effects of tobacco in shaping the oral microbiome, and analyse the available evidence in the light of the microbiome of oral potentially malignant and cancerous lesions, and the role of dysbiosis in carcinogenesis. Finally, we discuss possible interventions and approaches using which the oral microbiome could be leveraged towards precision-based oral cancer therapeutics.

Direct contact-based coculture of human dermal fibroblasts and epidermal keratinocytes has been a long-standing and challenging issue owing to different serum and growth factor requirements of the two cell types. Existing protocols employ high serum concentrations (up to 10% fetal bovine serum), complex feeder systems and a range of supplemental factors. These approaches are technically demanding and labor intensive, and pose scientific and ethical limitations associated with the high concentrations of animal serum. On the other hand, serum-free conditions often fail to support the proliferation of one or both cell types when they are cultured together. We have developed two reduced serum approaches (1–2% serum) that support the contact-based coculture of human dermal fibroblasts and immortalized keratinocytes and enable the study of cell migration and wound closure.

This protocol uses reduced serum formulations of FGM + KGM (1% serum) and MEM + FGS + KGS (2% serum) to co-culture human dermal fibroblasts and immortalized epidermal keratinocytes. The two cell lines are simultaneously seeded in the specific media formulations.

This protocol used reduced serum formulations of FGM + KGM (1% serum) and MEM + FGS + KGS (2% serum) to co-culture human dermal fibroblasts and immortalized epidermal keratinocytes in 6 well plates and study wound closure using a scratch assay.

This protocol uses reduced serum formulations of FGM + KGM (1% serum) and MEM + FGS + KGS (2% serum) to co-culture human dermal fibroblasts and immortalized epidermal keratinocytes. It uses a layering approach, with keratinocytes being layered onto confluent fibroblasts.

This article describes a science-art based activity organized as part of an orientation program for new students at a public university. Based on developing team-building skills and serving as an ‘ice-breaker’ for incoming students, this activity aims at creating a composite piece of art work depicting a scientific theme. In our experience, this activity is well-suited for implementation and improvisations as a collaborative, time-and cost-effective tool for student engagement in a classroom setting.

IntroductionTraditional medicinal remedies hold vast potential as novel antimicrobial agents, particularly for recalcitrant infection states such as biofilms. To explore their potential, it is important to bring these remedies out of ancient treatise and into present-day scientific evaluation. For traditional medical practices, this ‘development pipeline’ starts with probing treatise for potential remedies and testing them for anti-biofilm effects, or the ‘treatise to test’ phase.AimThe aim of this work is to present a primer for developing ‘ancientbiotics’ against biofilms, that focuses on the ‘treatise to test’ phase of the pipeline. Based on our approach and results, we provide insights into the considerations and challenges relevant to evaluating traditional remedies as anti-biofilm agents.MethodologyWe identified and reconstituted plant-based medicinal formulations from historical treatises of Indian traditional medicine, and analyzed their efficacy using widely-employed microtiter based assays, that constitute the cornerstone of biofilm studies. Measuring biomass and metabolic activity, we evaluated effects on biofilm formation and eradication of pre-formed biofilms, of Pseudomonas aeruginosa and Staphylococcus aureus.ResultsBased on recipes and preparation practices across several texts, and with modifications to ensure compatibility with modern scientific practices, three plant-based traditional remedies were identified and formulated in sesame oil (Bryophyllum pinnatum, Cynodon dactylon, and Ocimum tenuiflorum). We observed differential effects on biomass and metabolic activity on the biofilm formation and eradication of P. aeruginosa and S. aureus; highlighting the value of the microtiter-based assays as an initial screening tool for traditional remedies.ConclusionThrough this study, we provide insights into considerations relevant to the ‘treatise to test’ phase of the ‘ancientbiotics’ pipeline, such as identifying ancient remedies, reconstituting them with present-day modifications, and using in vitro assay formats for evaluation. The learnings in this primer will be relevant to both contemporary scientists and practitioners of ancient medicine, and will serve as a starting point for future studies exploring anti-biofilm approaches at the interface of historical and modern medicine.

Contact-based co-culture of fibroblasts and keratinocytes is important to study the structure and functions of the wound bed. Co-culture of these two cell types in direct contact with each other has been challenging, requiring high serum concentrations (up to 10%), feeder systems and a range of supplemental factors. These approaches are not only technically demanding, but also present scientific, cost and ethical limitations associated with high-serum concentrations. We have developed two reduced-serum approaches (1-2%) to support contact-based co-culture of human dermal fibroblasts (HDFa) and human epidermal keratinocytes (HaCaT). The two approaches include (1) Specialized cell culture media for each cell type mixed in a 1:1 ratio (KGM+FGM), and (2) Minimal media supplemented with cell-specific growth factors (MEM+GF). Co-culture could be successfully achieved by co-seeding (two cell types were introduced simultaneously), or in a layered fashion (keratinocytes seeded on top of confluent fibroblasts). With wound scratch assays, the co-cultured platforms could demonstrate cell proliferation, migration and wound closure. The reduced-serum conditions developed are simple, easy to formulate and adopt, and based on commonly-available media components. These contact-based co-culture approaches can be leveraged for wound and skin studies, and tissue bioengineering applications, potentially reducing concerns with high-serum formulations.

Chronic wound infections are an important cause of delayed wound healing, posing a significant healthcare burden with consequences that include hospitalization, amputation, and death. These infections most often take the form of three-dimensional biofilm communities, which are notoriously recalcitrant to antibiotics and immune clearance, contributing to the chronic wound state. In the chronic wound microenvironment, microbial biofilms interact closely with other key components, including host cellular and matrix elements, immune cells, inflammatory factors, signaling components, and mechanical cues. Intricate relationships between these contributing factors not only orchestrate the development and progression of wound infections but also influence the therapeutic outcome. Current medical treatment for chronic wound infections relies heavily on long-term usage of antibiotics; however, their efficacy and reasons for failure remain uncertain. To develop effective therapeutic approaches, it is essential to better understand the complex pathophysiology of the chronic wound infection microenvironment, including dynamic interactions between various key factors. For this, it is critical to develop bioengineered platforms or model systems that not only include key components of the chronic wound infection microenvironment but also recapitulate interactions between these factors, thereby simulating the infection state. In doing so, these platforms will enable the testing of novel therapeutics, alone and in combinations, providing insights toward composite treatment strategies. In the first section of this review, we discuss the key components and interactions in the chronic wound infection microenvironment, which would be critical to recapitulate in a bioengineered platform. In the next section, we summarize the key features and relevance of current bioengineered chronic wound infection platforms. These are categorized and discussed based on the microenvironmental components included and their ability to recapitulate the architecture, interactions, and outcomes of the infection microenvironment. While these platforms have advanced our understanding of the underlying pathophysiology of chronic wound infections and provided insights into therapeutics, they possess certain insufficiencies that limit their clinical relevance. In the final section, we propose approaches that can be incorporated into these existing model systems or developed into future platforms developed, thus enhancing their biomimetic and translational capabilities, and thereby their human-relevance.

Chronic wound infections are an important cause of delayed wound healing, posing a significant healthcare burden with consequences that include hospitalization, amputation, and death. These infections most often take the form of three-dimensional biofilm communities, which are notoriously recalcitrant to antibiotics and immune clearance, contributing to the chronic wound state. In the chronic wound microenvironment, microbial biofilms interact closely with other key components, including host cellular and matrix elements, immune cells, inflammatory factors, signaling components, and mechanical cues. Intricate relationships between these contributing factors not only orchestrate the development and progression of wound infections but also influence the therapeutic outcome. Current medical treatment for chronic wound infections relies heavily on long-term usage of antibiotics; however, their efficacy and reasons for failure remain uncertain. To develop effective therapeutic approaches, it is essential to better understand the complex pathophysiology of the chronic wound infection microenvironment, including dynamic interactions between various key factors. For this, it is critical to develop bioengineered platforms or model systems that not only include key components of the chronic wound infection microenvironment but also recapitulate interactions between these factors, thereby simulating the infection state. In doing so, these platforms will enable the testing of novel therapeutics, alone and in combinations, providing insights toward composite treatment strategies. In the first section of this review, we discuss the key components and interactions in the chronic wound infection microenvironment, which would be critical to recapitulate in a bioengineered platform. In the next section, we summarize the key features and relevance of current bioengineered chronic wound infection platforms. These are categorized and discussed based on the microenvironmental components included and their ability to recapitulate the architecture, interactions, and outcomes of the infection microenvironment. While these platforms have advanced our understanding of the underlying pathophysiology of chronic wound infections and provided insights into therapeutics, they possess certain insufficiencies that limit their clinical relevance. In the final section, we propose approaches that can be incorporated into these existing model systems or developed into future platforms developed, thus enhancing their biomimetic and translational capabilities, and thereby their human-relevance.

Chronic wounds are a major healthcare burden, with huge public health and economic impact. Microbial infections are the single most important cause of chronic, non-healing wounds. Chronic wound infections typically form biofilms, which are notoriously recalcitrant to conventional antibiotics. This prompts the need for alternative or adjunct ‘anti-biofilm’ approaches, notably those that account for the unique chronic wound biofilm microenvironment. In this review, we discuss the recent advances in non-conventional antimicrobial approaches for chronic wound biofilms, looking beyond standard antibiotic therapies. These non-conventional strategies are discussed under three groups. The first group focuses on treatment approaches that directly kill or inhibit microbes in chronic wound biofilms, using mechanisms or delivery strategies distinct from antibiotics. The second group discusses antimicrobial approaches that modify the biological, chemical or biophysical parameters in the chronic wound microenvironment, which in turn enables the disruption and removal of biofilms. Finally, therapeutic approaches that affect both, biofilm bacteria and microenvironment factors, are discussed. Understanding the advantages and limitations of these recent approaches, their stage of development and role in biofilm management, could lead to new treatment paradigms for chronic wound infections. Towards this end, we discuss the possibility that non-conventional antimicrobial therapeutics and targets could expose the ‘chink in the armor’ of chronic wound biofilms, thereby providing much-needed alternative or adjunct strategies for wound infection management.

Fast detection and identification of microorganisms is a challenging and significant feature from industry to medicine. Standard approaches are known to be very time-consuming and labor-intensive (e.g., culture media and biochemical tests). Conversely, screening techniques demand a quick and low-cost grouping of bacterial/fungal isolates and current analysis call for broad reports of microorganisms, involving the application of molecular techniques (e.g., 16S ribosomal RNA gene sequencing based on polymerase chain reaction). The goal of this review is to present the past and the present methods of detection and identification of microorganisms, and to discuss their advantages and their limitations. C.F.R. would like to thank the Portuguese Foundation for Science and Technology (FCT–Portugal) for the C.F.R. for the project UID/EQU/00511/2019—Laboratory for Process Engineering, Environment, Biotechnology, and Energy—LEPABE funded by national funds through FCT/MCTES (PIDDAC) and N.M. for the Strategic project ref. UID/BIM/04293/2013 and “NORTE2020 - Programa Operacional Regional do Norte” (NORTE-01-0145-FEDER-000012).

In infections, biofilm formation is associated with a number of fitness advantages, such as resistance to antibiotics and to clearance by the immune system. Biofilm formation has also been linked to fitness advantages in environments other than in vivo infections; primarily, biofilms are thought to help constituent organisms evade predation and to promote intercellular signaling. The opportunistic human pathogen Pseudomonas aeruginosa forms biofilm infections in lungs, wounds, and on implants and medical devices. However, the tendency toward biofilm formation originated in this bacterium’s native environment, primarily plants and soil. Such environments are polymicrobial and often resource-limited. Other researchers have recently shown that the P. aeruginosa extracellular polysaccharide Psl can bind iron. For the lab strain PA01, Psl is also the dominant adhesive and cohesive “glue” holding together multicellular aggregates and biofilms. Here, we perform quantitative time-lapse confocal microscopy and image analysis of early biofilm growth by PA01. We find that aggregates of P. aeruginosa have a growth advantage over single cells of P. aeruginosa in the presence of Staphylococcus aureus in low-iron environments. Our results suggest the growth advantage of aggregates is linked to their high Psl content and to the production of an active factor by S. aureus. We posit that the ability of Psl to promote iron acquisition may have been linked to the evolutionary development of the strong biofilm-forming tendencies of P. aeruginosa.

Biofilms are sessile communities of microbes that are spatially structured by an embedding matrix. Biofilm infections are notoriously intractable. This arises, in part, from changes in the bacterial phenotype that result from spatial structure. Understanding these interactions requires methods to control the spatial structure of biofilms. We present a method for growing biofilms from initiating cells whose positions are controlled with single-cell precision using laser trapping. The native growth, motility, and surface adhesion of positioned microbes are preserved, as we show for model organisms Pseudomonas aeruginosa and Staphylococcus aureus. We demonstrate that laser-trapping and placing bacteria on surfaces can reveal the effects of spatial structure on bacterial growth in early biofilm development.

Karishma Kaushik’s research at University of Pune focuses on chronic wound infections, from probing the complex wound infection microenvironment to enabling personalized therapeutic approaches. She is a recipient of the Ramalingaswami Re-entry Fellowship, a program funded by the Government of India to support the research of early-career scientists and their return to the country from abroad.

In this article, we attempt to chronicle some of the notable contributions of women in the Þ eld of medical microbiology. These extraordinary professionals include not only women physicians, but also researchers, therapists and technologists, each of whom is integral to the health care diagnostic system. These contributions form a continuum of female achievement - a heritage women in medical microbiology can proudly call their own. Lady Mary Wortley Montague (1689-1762) was an English aristocrat and wife of the then appointed ambassador to Turkey. It was in her endeavour to understand local customs that she learnt of the Turkish practice of inoculating healthy children with the attenuated strain of smallpox (variolation). Lady Mary introduced this custom in the British nobility with eventual Þ ltering down of the practice to the working classes. [1] Though Edward Jenner would eventually be given credit for the smallpox vaccine, it was really Lady Mary who pioneered the approach. As smallpox vaccination gained widespread acceptance eventually leading to eradication of the disease, millions of people owe their lives to Lady Mary Montague and her struggle to popularize smallpox inoculation. The name LanceÞ eld is associated throughout the world

A cost-effective and resource-efficient hands-on educational module that uses an interdisciplinary approach to characterize antimicrobial compounds, combining microbiology experiments and a physics-based analytical model., We have developed a hands-on experimental module that combines biology experiments with a physics-based analytical model in order to characterize antimicrobial compounds. To understand antibiotic resistance, participants perform a disc diffusion assay to test the antimicrobial activity of different compounds and then apply a diffusion-based analytical model to gain insights into the behavior of the active antimicrobial component. In our experience, this module was robust, reproducible, and cost-effective, suggesting that it could be implemented in diverse settings such as undergraduate research, STEM (science, technology, engineering, and math) camps, school programs, and laboratory training workshops. By providing valuable interdisciplinary research experience in science outreach and education initiatives, this module addresses the paucity of structured training or education programs that integrate diverse scientific fields. Its low-cost requirements make it especially suitable for use in resource-limited settings.

Answer: Serratia marcescens. The isolate was a Gram-negative bacillus, a non-lactose fermenter, a glucose and sucrose fermenter with production of gas, catalase and Voges-Proskauer positive, and oxidase and methyl red negative. The bacterium produced DNase, lipase, and gelatinase and was ornithine

Increasing antibiotic resistance and the declining rate at which new antibiotics come into use create a need to increase the efficacy of existing antibiotics. The aminoglycoside tobramycin is standard-of-care for many types of Pseudomonas aeruginosa infections, including those in the lungs of cystic fibrosis (CF) patients. P. aeruginosa is a nosocomial and opportunistic pathogen that, in planktonic form, causes acute infections and, in biofilm form, causes chronic infections. Inhaled bicarbonate has recently been proposed as a therapy to improve antimicrobial properties of the CF airway surface liquid and viscosity of CF mucus. Here we measure the effect of combining tobramycin and bicarbonate against P. aeruginosa, both lab strains and CF clinical isolates. Bicarbonate synergises with tobramycin to enhance killing of planktonic bacteria. In contrast, bicarbonate antagonises with tobramycin to promote better biofilm growth. This suggests caution when evaluating bicarbonate as a therapy for CF lungs infected with P. aeruginosa biofilms. We analyse tobramycin and bicarbonate interactions using an interpolated surface methodology to measure the dose–response function. These surfaces allow more accurate estimation of combinations yielding synergy and antagonism than do standard isobolograms. By incorporating predictions based on Loewe additivity theory, we can consolidate information on a wide range of combinations that produce a complex dose–response surface, into a single number that measures the net effect. This tool thus allows rapid initial estimation of the potential benefit or harm of a therapeutic combination. Software code is freely made available as a resource for the community.

Illicit drug control has been on the global agenda for more than a century. Infections have long been recognized as one of the most serious complications of drug abuse. Drug users are susceptible to pulmonary, endovascular, skin and soft tissue, bone and joint, and sexually transmitted infections caused by a wide range of bacterial, viral, fungal and protozoal pathogens. In addition, injection drug users are at increased risk for parenterally acquired infections such as human immunodeficiency virus, hepatitis B virus, hepatitis C virus, tetanus and malaria. Factors related to drug use, such as unsterile injection practices, contaminated drug paraphernalia and drug adulterants, increase the exposure to microbial pathogens. Illicit drugs also affect several components of the complex immune system and thus modulate host immunity. In addition, lifestyle practices such as multiple sexual partners, overcrowded housing arrangements and malnutrition serve as co-factors in increasing the risk of infection. In this review we present an overview of the unique aspects of microbial pathogenesis, immune modulation and common infections associated with drug use. We have restricted the definition of drug abuse to the use of illegal drugs (such as opiates, marijuana, cocaine, heroin and amphetamines), not including alcohol and nicotine.

With the introduction of varicella vaccination in India, surveillance of circulating varicella-zoster strains has gained significance. The aim of the present study was to achieve molecular characterization of circulating varicella-zoster virus (VZV) strains and differentiation from the Oka vaccine strain. In this study, the genotype of 100 clinical VZV strains was analyzed. Vesicle fluid was collected from patients with VZV infections (92 cases of varicella and 8 cases of herpes zoster). The PCR-RFLP analysis of two polymorphic loci--a PstI restriction site in ORF 38 and a BglI restriction site in ORF 54 was used to characterize and differentiate them from the vaccine strain. All the wild-type strains were positive for the PstI restriction site in ORF 38. This differentiated them from the Oka vaccine strain, which is PstI negative. The wild-type strains as well as the Oka vaccine strain were positive for the BglI restriction site in ORF 54. Thus, the genotype of all the VZV strains examined had the wild-type pattern represented as PstI(+) BglI(+). None of the strains had the PstI(-) BglI(+) genotype characteristic of the Oka strain or the PstI(+) BglI(-) wild-type pattern. To conclude, PstI and BglI serve as good reference markers in the genotyping of circulating varicella strains in India and serve to differentiate them from the vaccine strain as well as other wild-type strains.

Antibiotic resistance adversely affects clinical and public health on a global scale. Using the opportunistic human pathogen Pseudomonas aeruginosa , we show that increasing the number density of bacteria, on agar containing aminoglycoside antibiotics, can non-monotonically impact the survival of antibiotic-resistant mutants. Notably, at high cell densities, mutant survival is inhibited. A wide range of bacterial species can inhibit antibiotic-resistant mutants. Inhibition results from the metabolic breakdown of amino acids, which results in alkaline by-products. The consequent increase in pH acts in conjunction with aminoglycosides to mediate inhibition. Our work raises the possibility that the manipulation of microbial population structure and nutrient environment in conjunction with existing antibiotics could provide therapeutic approaches to combat antibiotic resistance.