Tag: antibiotic resistance

Categories : Diseases, Syndromes and ConditionsTags :

The Emerging Treatment-resistant Fungus Threat

On By ModernMedia

Professor Rodney E. Rohde, a public health and clinical microbiology expert at Texas State University, warned in article for The Conversation of the growing threat of fungal resistance — a problem drawing much less attention than antibiotic resistance. 

 Athlete’s foot, thrush, ringworm and other ailments are caused by fungi, and some are serious risks to health and life. Among these is Candida auris, a pathogenic fungus. Fungi generally have not caused major disease, so there is a lack of funding in this area and there are limited antifungal agents that can treat C. auris.

Most fungal infections around the world are caused by the genus Candida, particularly the species called Candida albicans. But there are others, including Candida auris, which gets its name ‘auris’, Latin for ear, because it was first identified from an external ear canal discharge in 2009.

Candida normally lives on the skin and inside the body, such as in the mouth, throat, gut and vagina, without causing any problems. It exists as a yeast and is thought of as normal flora, harmless microbes. However when the body is immuno-compromised, these fungi become opportunistic pathogens, something happening around the world with multidrug-resistant C. auris.

The threat of Candida auris

C. auris infections, or fungaemia, have been reported in 30 or more countries. They are often found in the blood, urine, sputum, ear discharge, cerebrospinal fluid and soft tissue, and occur in people of all ages. According to the US Centers for Disease Control, the mortality rate in the US has been reported to be between 30% to 60% in many patients who had other serious illnesses. In a 2018 review of research on the global spread of the fungus, researchers estimated mortality rates of 30% to 70% in C. auris outbreaks among critically ill patients in intensive care.

Recent surgery, diabetes and broad-spectrum antibiotic and antifungal use are risk factors. Furthermore, immuno-compromised patients are at greater risk than those with healthy immune systems.

C. auris can be difficult to identify with conventional microbiological culture techniques, which leads to frequent mis-identification and under recognition. This yeast is also known for its tenacity to easily colonise the human body and environment — including medical devices. People in nursing homes and patients with catheters, on ventilation etc seem to be at highest risk.

The CDC has set C. auris infections at an “urgent” threat level because 90% are resistant to at least one antifungal, 30% to two antifungals, and there are some resistant to all three available classes of antifungals. This multidrug resistance has led to outbreaks in health care settings, especially hospitals and nursing homes, that are extremely difficult to control.

The double threat of COVID and C. auris

For hospitalised COVID patients, antimicrobial-resistant infections may be a particularly devastating risk. The mechanical ventilators often used to treat serious COVID are breeding grounds and highways for entry of environmental microbes like C. auris. Further, according to a September 2020 paper, hospitals in India treating COVID have detected C. auris on surfaces including “bed rails, IV poles, beds, air conditioner ducts, windows and hospital floors.” The researchers termed the fungus a “lurking scourge” amid the COVID pandemic. Termed ‘white fungus’, these fungal infections typically arise a week to 10 days after being in the ICU.

The same authors reported in a November 2020 CDC article that of 596 COVID-confirmed patients in a New Delhi ICU from April 2020 to July 2020, 420 patients required mechanical ventilation. Of these, 15 were infected with candidemia fungal disease and eight of those infected (53%) died. Ten of the 15 patients were infected with C. auris; six of them died (60%).

How to deal with this?

With fewer and fewer antifungal options,  CDC is recommending a focus on preventing C. auris infections. This involves better hand hygiene and improving infection prevention and control in medical care settings, judicious and thoughtful use of antimicrobial medications, and stronger regulation limiting the over-the-counter availability of antibiotics.

Source: The Conversation

Journal information: Anuradha Chowdhary et al, The lurking scourge of multidrug resistant Candida auris in times of COVID-19 pandemic, Journal of Global Antimicrobial Resistance (2020). DOI: 10.1016/j.jgar.2020.06.003

Categories : Diseases, Syndromes and Conditions Immune SystemTags :

In the Immune Battle, MRSA Uses Toxins to Fight Dirty

On By ModernMedia
Scanning electron micrograph of methicillin-resistant Staphylococcus aureus and a dead human neutrophil. Credit: NIAID

Researchers have uncovered a novel trick employed by the bacterium Staphylococcus aureus — MRSA uses toxins to ‘fight dirty’ and stifle the immune response. This finding is a step towards one day producing a vaccine against MRSA.

Every year, there are some 700 000 deaths due to the emerging global threat of antimicrobial resistance (AMR). Turning the tables against AMR requires immediate action, and the development of novel vaccines to prevent such infections in the first place, are an attractive and potentially very effective option.

Staphylococcus aureus is the causative agent of the infamous MRSA ‘superbug’, one of the chief concerns of AMR. Immunologists from Trinity College Dublin, working with scientists at GSK, discovered the deadly bacteria’s new trick to foil the immune system. They found that the bacterium interferes with the host immune response by causing toxic effects on white blood cells, preventing them from carrying out their infection-fighting jobs.

The study also showed that the toxicity could be lessened following vaccination with a mutated version of a protein specifically engineered to throw a spanner in the MRSA works. This could one day lead to a vaccine for humans.

Rachel McLoughlin, Professor in Immunology in Trinity’s School of Biochemistry and Immunology and the Trinity Biomedical Sciences Institute (TBSI), said: “As a society we are witnessing first-hand the powerful impact that vaccination can have on curbing the spread of infection. However, in the backdrop of the COVID epidemic we must not lose sight of the fact that we are also waging war on a more subtle epidemic of antimicrobial resistant infection, which is potentially equally deadly.

“In this study we have identified a mechanism by which a protein made by the bacterium – known as Staphylococcal Protein A (SpA) – attacks and rapidly kills white blood cells. This protein has been widely studied for its immune evasion capacity and has a well-documented role in rendering antibodies raised against the bacterium non-functional.

“Here we uncover a previously undocumented strategy by which SpA forms immune complexes through its interaction with host antibodies, that in turn exert toxic effects on multiple white blood cell types. This discovery highlights how important it will be for effective vaccines to be capable of disarming the effects of protein A.”

Dr Fabio Bagnoli, Director, Research & Development Project Leader, GSK, said: “Our collaboration with Trinity College Dublin and in particular with Professor Rachel McLoughlin, a worldwide recognised expert on staphylococcal immunology, is critical for increasing our knowledge on protective mechanisms against S. aureus.”

The study documents the latest discovery made by this group at Trinity under an ongoing research agreement with GSK Vaccines (Siena, Italy). Overall, this collaboration aims to increase understanding of the immunology of Staphylococcus aureus infection to advance development of next-generation vaccines to prevent MRSA infections.

Source: Trinity College Dublin

Journal information: Fox, P. G., et al. (2021) Staphylococcal Protein A Induces Leukocyte Necrosis by Complexing with Human Immunoglobulins. Scientific Reports. doi.org/10.1128/mBio.00899-21.

Categories : AntibioticsTags :

Disarming a Common Pathogenic Bacterium

On By ModernMedia
Pseudomonas aeruginosa bacteria. Source: Public Health Imagery Library

Scientists have discovered a gene regulator in a common pathogenic bacterium that can be exploited to drastically reduce its virulence.

Pseudomonas aeruginosa is a gram-negative, aerobic, opportunistic, pathogenic bacterium found in a variety of ecological niches, such as plant roots, stagnant water or even plumbing. Naturally extremely versatile, it can cause acute and chronic infections that are potentially fatal for immunocompromised hosts. P. aeruginosa poses a serious threat in clinical settings, where it can colonise respirators and catheters. Additionally, its adaptability and resistance to many antibiotics make P. aeruginosa infections steadily more difficult to treat. Therefore new antibacterials are urgently needed. 

Scientists from the University of Geneva (UNIGE) in Switzerland have identified a previously unknown regulator of gene expression in this bacterium, without which the infectious power of P. aeruginosa is diminished. This discovery may unlock new developmental pathways to treat this bacteria.

RNA helicases perform essential regulatory functions by binding and unwinding various RNA molecules to perform their functions. RNA helicases are present in the genomes of almost all known living organisms, including bacteria, yeast, plants, and humans; however, they have acquired specific properties depending on the organism in which they are found. “Pseudomonas aeruginosa has an RNA helicase whose function was unknown, but which was found in other pathogens”, explained Martina Valentini,  a researcher leading this research in the Department of Microbiology and Molecular Medicine at UNIGE Faculty of Medicine. “We wanted to understand what its role was, in particular in relation to the pathogenesis of the bacteria and their environmental adaptation.”

A severely reduced virulence

To accomplish this, the researchers took a combined biochemical and molecular genetic approach. “In the absence of this RNA helicase, P. aeruginosa multiplies normally in vitro, both in a liquid medium and on a semi-solid medium at 37°C”, reported Stéphane Hausmann, a researcher associate in the Department of Microbiology and Molecular Medicine at UNIGE Faculty of Medicine and first author of this study. “To determine whether the infection capacity of the bacteria was affected, we had to observe it in vivo in a living organism.”

The scientists then continued their research using Galleria mellonella larvae, a model insect for studying host-pathogen interactions.These larvae can live at temperatures between 5°C and 45°C, which makes it possible to study bacterial growth at different temperatures, including that of the human body. Three groups of larvae were observed, including a control group injected with saline. In the presence of a normal strain of P. aeruginosa, less than 20% survived at 20 hours after infection. In contrast, when P. aeruginosa lacked the RNA helicase gene, over 90% of the larvae remained alive. “The modified bacteria became almost harmless, while remaining very much alive,” says Stéphane Hausmann.

Inhibiting instead of killing

The findings demonstrated that the regulator affects production of several virulence factors in the bacteria. “In fact, this protein controls the degradation of numerous messenger RNAs coding for virulence factors”, summarised Martina Valentini. “From an antimicrobial drug strategy point of view, switching off the pathogen’s virulence factors rather than trying to eliminate the pathogen completely, means allowing the host immune system to naturally neutralise the bacterium and potentially reduces the risk for the development of resistance. Indeed, if we try to kill the bacteria at all costs, the bacteria will adapt to survive, which favours the appearance of resistant strains.”

The Geneva team is continuing its investigations by screening drug molecules to see if any of them can selectively block this protein, and also performing a detailed study in detail on the inhibition mechanisms on which could be based the development of an effective therapeutic strategy.

Source: University of Geneva

Journal reference: Hausmann, S., et al. (2021) The DEAD-box RNA helicase RhlE2 is a global regulator of Pseudomonas aeruginosa lifestyle and pathogenesis. Nucleic Acid Research. doi.org/10.1093/nar/gkab503.

Categories : AntibioticsTags :

Holding off on Antibiotics is Safe and Effective for Patients

On By ModernMedia

According to an analysis published in BMJ Today, delayed antibiotic prescribing is a safe and effective strategy for most patients with respiratory tract infections.

Delayed antibiotic prescribing—also known as ‘just in case prescribing’—is when patients agree to see whether symptoms settle before collecting a prescription, in order to help reduce antibiotic use.

Delayed prescribing was shown to be associated with a similar duration of symptoms as no antibiotic prescribing and is not likely to lead to poorer symptom control than immediate antibiotic prescribing. In children with immediate antibiotics a slight benefit was seen but this was not judged important enough to justify immediate antibiotic prescribing.

Respiratory tract infections affect the sinuses, throat, airways or lungs and include conditions such as the common cold, sore throat, cough and ear infection. While most improve without treatment, antibiotics are still widely being prescribed for these conditions.

It has been suggested in various clinical trials that delayed antibiotic prescribing for respiratory tract infections is probably safe and effective for most patients, but they were unable to examine different groups of patients or complications.

To address this, an international research team set out to assess the effect of delayed antibiotic prescribing on symptoms for patients with respiratory tract infections in the community.

They used individual patient data on a total of 55 682 patients from nine randomised controlled trials and four observational studies to compare average symptom severity between delayed versus no antibiotic prescribing, and delayed versus immediate antibiotic prescribing.

Most of the studies took place in primary care settings with the average age of study participants ranging from 2.7 to 51.7 years.

The researchers accounted for factors including age, sex, previous duration of illness, severity of symptoms, smoking status and underlying conditions. Average symptom severity was measured two to four days after initial consultation on a seven point scale (ranging from normal to as bad as could be).

The researchers found no difference in symptom severity for delayed versus immediate antibiotics or delayed versus no antibiotics.

Symptom duration was slightly longer in those given delayed versus immediate antibiotics (11.4 v 10.9 days), but was similar for delayed versus no antibiotics.

Complications resulting in hospital admission or death were lower with delayed versus no antibiotics and delayed versus immediate antibiotics, but neither result was statistically significant.

Re-consultation rates were significantly reduced and an increase in patient satisfaction were found for delayed versus no antibiotics, but not for delayed versus immediate antibiotics.

Children under 5 years of age showed slightly more severe symptoms with delayed antibiotics than with immediate antibiotics, but this was not considered to be clinically meaningful, and this was not seen in older age groups.

 hey concluded that delayed antibiotic prescribing “appears to be a safe and effective strategy for most patients, including those in higher risk subgroups.”

This was a large, detailed analysis accounting for differences in study design and quality to reduce bias. The researchers nevertheless pointed out some limitations, being unable to exclude the possibility that other unmeasured factors may have affected their results.

Source: Medical Xpress

Journal information: Beth Stuart et al, Delayed antibiotic prescribing for respiratory tract infections: individual patient data meta-analysis, BMJ (2021). DOI: 10.1136/bmj.n808

Categories : AntibioticsTags :

WHO Says New Antibiotic Treatments are Falling Behind

On By ModernMedia

The development projects of new antibiotic treatments are falling behind, despite increasing awareness of the antibiotic resistance threat, according to a recently released report by the World Health Organization. 

The WHO revealed that none of the 43 antibiotics that are currently in clinical development sufficiently address the problem of drug resistance in the world’s most dangerous bacteria.

Dr Hanan Balkhy ,Assistant Director General on AMR, WHO said that, “The persistent failure to develop, manufacture, and distribute effective new antibiotics is further fueling the impact of antimicrobial resistance (AMR) and threatens our ability to successfully treat bacterial infections.”

All of the new antibiotics released onto the market in the past few decades have been variations of those developed in the 1980s.

The impact of AMR is most severely felt in resource-constrained settings and in vulnerable populations such young children. Bacterial pneumonia and bloodstream infections are some of the major causes of childhood mortality under age 5, and about 30% of neonates with sepsis die due to bacterial infections resistant to multiple first-line antibiotics.

WHO puts out its Antibacterial Pipeline Report every year, reviewing antibiotics under development. The report evaluates the potential of the candidates to address the most threatening drug-resistant bacteria outlined in the WHO Bacterial Priority Pathogens List (WHO PPL). Since it began in 2017, this list, which includes 13 priority drug-resistant bacteria, has informed and guided priority areas for research and development.

The 2020 report paints a picture of an almost stalled pipeline with only few antibiotics in recent years receiving regulatory approval. Most of these agents in development have little extra clinical benefit over current ones, with 82% of recently approved antibiotics being derivatives of previous  ones with well-established drug-resistance, and drug resistance to these new ones is expected to emerge rapidly.

The review concludes that “overall, the clinical pipeline and recently approved antibiotics are insufficient to tackle the challenge of increasing emergence and spread of antimicrobial resistance”.

Speeding up development requires innovative approaches. For the first time. the 2020 WHO pipeline report includes a comprehensive overview of non-traditional antibacterial medicines, detailing 27 antibacterial agents in the pipeline. These range from antibodies to bacteriophages and therapies that boost the immune response and weaken bacterial effects.

The report notes that there are some promising products in different stages of development. However, only a fraction of these will ever make it to the market due to the economic and inherent scientific challenges in the drug development process. This, along with the small return on investment from successful antibiotic products, has limited the interest of major private investors and most large pharmaceutical companies.

Only a fraction of the promising products in the pipeline will make it to market because of financial and scientific obstacles in the development process. 

The preclinical and clinical pipelines continue to be driven by small- and medium-sized companies, which often struggle to finance their products through clinical trials and approval.

The COVID pandemic has deepened the global understanding of the health and economic implications of uncontrolled disease, as well as funding gaps, including investments in R&D of antimicrobial medicines and vaccines, while also demonstrating that much can be achieved with political will and sufficient funding.

“Opportunities emerging from the COVID-19 pandemic must be seized to bring to the forefront the needs for sustainable investments in R&D of new and effective antibiotics,” said Haileyesus Getahun, Director of AMR Global Coordination at WHO. “Antibiotics present the Achilles heel for universal health coverage and our global health security. We need a global sustained effort including mechanisms for pooled funding and new and additional investments to meet the magnitude of the AMR threat.”

To address funding challenges in antibiotics development, WHO partnered with the Drugs for Neglected Diseases intitive (DNDi) to set up the Global Antibiotic R&D Partnership (GARDP) to develop promising treatments.

In addition, the WHO has been working closely with other non-profit funding partners such as the CARB-X to “push” and accelerate antibacterial research. Another important new initiative is the AMR Action Fund, a partnership by the European Investment Bank. pharmaceutical companies and philanthropies.

Source: News-Medical.Net

Categories : Medical Research & TechnologyTags :

Harnessing Tailocins, Antibacterial ‘Homing Missiles’

On By ModernMedia

A Berkeley Lab-led team is investigating how to harness tailocins, antibacterial nanomachine ‘weapons’ akin to phages but produced by certain bacteria in suicide attacks against other strains.

“Tailocins are extremely strong protein nanomachines made by bacteria,” explained Vivek Mutalik, a research scientist at Lawrence Berkeley National Laboratory (Berkeley Lab) who studies tailocins and phages, the bacteria-infecting viruses that tailocins appear to be remnants of. “They look like phages but they don’t have the capsid, which is the ‘head’ of the phage that contains the viral DNA and replication machinery. So, they’re like a spring-powered needle that goes and sits on the target cell, then appears to poke all the way through the cell membrane making a hole to the cytoplasm, so the cell loses its ions and contents and collapses.”

Many bacteria can produce tailocins, seemingly under stress conditions. However, the tailocins are only lethal to specific strains, and seem to be used by bacteria to compete with rivals. Since they are so similar to phages, scientists believe that tailocins are repurposed from DNA that was injected into bacterial genomes from viral infections.

According to Mutalik, tailocins kill the bacteria that produce them as they erupt through the membrane, much the way replicated viruses do. However, once released, the tailocins selectively target certain strains and not the host lineage cells.

“They benefit kin but the individual is sacrificed, which is a type of altruistic behavior. But we don’t yet understand how this phenomenon happens in nature,” Mutalik commented. Scientists also don’t know precisely how the stabbing needle plunger of the tailocin functions.

These topics, and tailocins as a whole, are an area of hot research due to the many possible applications. Mutalik and his colleagues in Berkeley Lab’s Biosciences Area along with collaborators at UC Berkeley are interested in harnessing tailocins to better study microbiomes. Other groups are keen to use tailocins as an alternative to traditional antibiotics -which indiscriminately wipe out beneficial strains alongside the bad and are increasingly ineffective due to the evolution of drug-resistance traits.
There is also great interest in using tailocins as an alternative to antibiotics, due to increasing antibiotic resistance and the fact that conventional antibiotics wipe out beneficial strains along with the disease-causing ones.

In their most recent paper, the collaborative Berkeley team explored the genetic basis and physical mechanisms governing how tailocins attack specific strains, and looked at genetic similarities and differences between tailocin producers and their target strains.

Upon examination of 12 strains of tailocin-using soil bacteria, the researchers found that differences in the lipopolysaccharides on the outer membranes determined whether they were targeted by a particular tailocin.

“The bacteria we studied live in a challenging, resource-poor environment, so we’re interested to see how they might be using tailocins to fight for survival,” said co-lead author Adam Arkin, a senior faculty scientist in the Biosciences Area and technical co-manager of the Ecosystems and Networks Integrated with Genes and Molecular Assemblies (ENIGMA) Scientific Focus Area. Arkin observed that although bacteria can easily be induced to produce tailocins in the lab, as well as scale up for mass production for medicinal applications, it is not well understood how bacteria deploy tailocins in their natural environment, and how or why particular strains are so precisely targeted.

“Once we understand the targeting mechanisms, we can start using these tailocins ourselves,” Arkin added. “The potential for medicine is obviously huge, but it would also be incredible for the kind of science we do, which is studying how environmental microbes interact and the roles of these interactions in important ecological processes, like carbon sequestration and nitrogen processing.”

At the moment, it is difficult to observe what is happening in a bacterial community, but tailocins could remove individual strains with precision to allow a better understanding of the situation.

Follow-up studies being conducted involve taking atomic-level images of the taolicins in action.

Source: SciTech Daily

Journal information: “Systematic discovery of pseudomonad genetic factors involved in sensitivity to tailocins” by Sean Carim, et al., 1 March 2021, The ISME Journal. DOI: 10.1038/s41396-021-00921-1

Categories : Diseases, Syndromes and ConditionsTags :

Premature Death Risk Doubled for Patients With Superbug on Their Skin

On By ModernMedia

Adults middle-aged or older who carry methicillin-resistant Staphylococcus aureus (MRSA) ‘superbug’ on their skin are twice as likely to die within the next decade as people who do not, according to a study by the University of Florida (UF).

“Very few people who carry MRSA know they have it, yet we have found a distinct link between people with undetected MRSA and premature death,” said lead author Arch Mainous, PhD, a professor in the department of health services research, management and policy at UF.

The findings suggest that routine screening for undetected MRSA may be warranted in older people to prevent deaths from infection.

A third of Americans carry Staphylococcus aureus, or staph, on their skin or in nasal passages, and of these about 1% carry MRSA, the notorious antibiotic resistant staph strain.

MRSA carriers may not even be aware that they carry the bacteria unless they develop an infection or are tested for it. A quarter of people who carry MRSA without an active infection, known as colonised MRSA for at least a year, eventually develop a MRSA infection.

“MRSA can be part of normal body flora, but it can lead to infection when immune systems are compromised, especially in people who are hospitalized, have underlying disease, or after antibiotic use,” said Prof Mainous, also vice chair for research in the UF College of Medicine’s department of community health and family medicine.

According to a 2017 Centers for Disease Control and Prevention report, 119 000 Americans experienced a staph bloodstream infection and nearly 20 000 died. Hospitalised patients with colonised MRSA may be particularly vulnerable to  infection in hospital or after discharge. Among carriers, wounds, surgical incisions and use of medical devices, such as catheters, may also lead to MRSA infection.

In this study, researchers analysed data from the 2001-2004 National Health and Nutrition Examination Survey, a nationally representative study combining survey questions with laboratory testing, which includes nasal swabs for detecting MRSA.

Adjusting for risk factors including gender and ethnicity, the researchers linked data on participants ages 40-85 with data from the National Death Index to track deaths over an 11-year period.

The mortality rate among participants without MRSA was about 18% compared with 36% among those with colonised MRSA. There was no increased mortality risk for those with non-MRSA staph bacteria on their skin.

Although some states and hospital systems require MRSA testing for patients before hospital admission, policies for testing and treatment of colonised MRSA, which may include antibiotics use, vary widely betweens hospitals, Prof Mainous said.

“Without a uniform strategy, we are missing an opportunity to help prevent deaths caused by MRSA,” he said. “Maybe we should know who is carrying MRSA.”

Source: Medical-News.Net

Journal information: Mainous, A. G., et al. (2021) Methicillin-Resistant Staphylococcus Aureus Colonization and Mortality Risk Among Community Adults Aged 40-85. Journal of the American Board of Family Medicine.

Categories : Diseases, Syndromes and Conditions Expert OpinionTags :

Microbes Develop Resistance to Disinfectant Too, Warns UFS Professor

On By ModernMedia

News-Medical.Net interviewed Professor Robert Bragg of the University of the Free State on the topic of pathogens, particularly bacteria, developing resistance to common disinfectants.

Professor Robert Bragg said that the control of diseases rests on three pillars: 1) vaccinations and vaccines, 2) treatment options (such as antibiotics for bacterial diseases), and 3) biosecurity.

Proff Brage explained that 10 to 15 years ago, there was an assumption that bacteria would not evolve resistance against disinfectants, but the COVID pandemic prompted a rethink. Now, disinfectant resistance is being looked at in the same light as antibiotic resistance. Biosecurity, he said, is ensuring that individuals do not come into contact with the pathogens in the first place. This is easily seen in the COVID pandemic, where face masks are worn (with a protection against contracting the disease of up to 70%), social distancing is enforced and hands and surfaces are sanitised. Though Prof Bragg’s main area of research is not antibiotic resistance, he notes that, “There are resistance mechanisms that are shared between antibiotics and disinfectants and we are looking at how these mechanisms increase resistance to disinfectants.” 

The protection of antibiotics is something taken for granted, but although mostly easily treatable (for now), bacteria can spread much faster than viruses, which require cells to reproduce in and whose re[plication rate is measured in days. “A common well-known bacterium such as Escherichia coli has a doubling time of around 20 min under ideal conditions. In other words, it only takes just 20 minutes for a population of E. coli to go from 1 million to 2 million and another 20 mins to reach 4 million, and so on,” Prof Bragg said. In the post-antibiotic era, there would be some treatment options such as bacteriophages, but for livestock the best protection would be biosecurity. However, disinfectant resistance would reduce the effectiveness of that option.

His research team has conducted a number of studies into the mechanisms of bacterial disinfectant resistance. “My research team has been working on various aspects of efficacy and resistance to disinfectants for quite some time and we have various projects that are currently underway,” he said. “Recently we identified a highly resistant strain of a Serratia species of bacteria. This strain was substantially more resistant to many different disinfectants than the reference strain. This great difference in the levels of susceptibility has allowed us to investigate various possible research mechanisms and also to look for possible novel resistance mechanisms.”

One of his team’s discoveries was that this highly resistant bacteria strain could grow on disinfectant if it was the sole source of carbon. Other areas of research around the resistant strain include sequencing and analysis of its genome, the role of bacterial efflux pumps removing disinfectant, and the role of plasmids (vehicles of genetic transfer between bacteria) in resistance and whether they are transferrable.

With regard to viruses, there are two kinds of viruses, enveloped and naked, and disinfectant has different effects on them. Enveloped viruses such as SARS-CoV-2, have a lipid layer picked up from their host cell, and are easy to kill with simple disinfectants because they break up the lipid layer, killing the cell. Naked cells are much harder to kill, and the few disinfectants that work against them are thought to do so by somehow disrupting the virus’ receptors.

One sanitiser of concern is alcohol, where 70% is considered optimal. However, people believe that ‘more is better’, yet increasing the alcohol percentage actually makes it evaporate faster, reducing contact time and thus leaving more of the virus behind. Similarly, some sanitisers include low levels of other disinfectant substances which are below the minimum threshold to kill the pathogens. This can leave surviving bacteria to develop resistance against these other sanitisers.

Prof Bragg advised that the public should purchase and use sanitisers prudently, following their instructions for use appropriately, and preferably checking to see if they are registered. He also cautioned

Source: News-Medical.Net

Categories : Diseases, Syndromes and ConditionsTags :

International Travellers at Risk of MDR Bacteria

On By ModernMedia

International travellers are at risk of picking up a number of drug-resistant pathogens, according to a new European study.

In the COVID pandemic, international travel has become a distant memory for most of those used to it. As restrictions are lifted and international travel resumes, travellers are still at risk from other dangerous pathogens. In recent years, the rise of intestinal multidrug resistant gram-negative (MDR-GN) bacteria around the world poses a serious health threat, with MDR clones of E.coli and Klebsiella pneumoniae threatening more antibiotic resistant infections around the world. The spread of MDR-GN is a known threat in long-term care facilities, with residents forming a reservoir for the microbes but is also common in international travel as well. It is well documented that international travel results in the spread of multidrug-resistant E. coli, with up to 80% of travellers returning from high-risk regions being colonised by MDR-GN bacteria for up to a year. However, the existing research only compared participants before and after travel. A group of researchers from Universities of Basel, Birmingham, Helsinki and Oslo, and the Wellcome Sanger Institute set out to investigate the spread of such bacteria on a day by day basis.

Over a period of three weeks, the researchers monitored the health of a group of European travellers in the Lao People’s Democratic Republic by analysing daily information returns and stool samples. They found that by the end of the study period, 70% of the travellers had been colonised. The bacterial strains colonised travellers staying at the same hotel and spending time in one another’s company. In one case, a participant was colonised by taking a shower in another’s bathroom.

“International travel is strongly linked to the spread of MDR-GN bacteria, with transmission highest in India and Southeast Asia, Africa and South America,” said senior study author Professor Alan McNally, University of Birmingham. “Travellers visiting these high-risk regions are at substantial risk of acquiring the bacteria. Colonisation by MDR-GN bacteria is a highly dynamic process. We found constant ‘competition’ between circulating strains acquired by individual hosts and the travelers’ ‘native’ bacteria. Travellers can pick up the bacteria even during short visits and further spread the strains after returning home.”

All of the participants had acquired extended-spectrum beta-lactamases (ESBL) during their stay in Laos. ESBL enzymes create resistance within the body to most beta-lactam antibiotics, including penicillins, cephalosporins, and aztreonam. Infections with ESBL-producing organisms have proved difficult to treat. Also, all but one participant acquired multiple strains of bacteria with 83 unique strains identified (53 E. coli, 10 Klebsiella, 20 other ESBL-GN species), with up to four other participants sharing strains.

Study co-senior author, Professor Jukka Corander, at the University of Oslo and the Wellcome Sanger Institute, commented: “Our study reveals the true scale and complexity at which drug-resistant bacteria colonise the intestinal tract during travel, demonstrating that it has been seriously underestimated previously.

“In addition, several of our participants lost some of their travel-acquired ESBL-GN strains while still abroad – indicating that previous studies solely employing pre- and post-travel sampling have under-reported the extent to which travellers are colonised by ESBL-GN.”

Source: News-Medical.Net

Journal information: Kantele, A., et al. (2021) Dynamics of intestinal multidrug-resistant bacteria colonisation contracted by visitors to a high-endemic setting: a prospective, daily, real-time sampling study. The Lancet Microbe. doi.org/10.1016/S2666-5247(20)30224-X.

Categories : AntibioticsTags :

Prevalence of Antibiotic Resistance is Underestimated

On By ModernMedia

Antibiotic resistance to pathogenic bacteria in humans has spread farther than expected, as it has been discovered that bacteria can swap DNA far more readily than thought possible.

A growing threat, antibiotic resistance has emerged faster than thought possible. Some 33 000 deaths have occurred to antibiotic resistant infections in Europe alone, and finding new antibiotics or even alternatives are a top research priority. Totally different strains of bacteria can swap genetic information through the use of containers called plasmids. Plasmids are small containers of DNA which are kept outside of their chromosomes. When two bacteria come into contact, they can copy plasmids to one another in a process called conjugation (also known as “bacterial sex“). This is the most important means by which bacteria spread antibiotic resistance.

“In recent years, we’ve seen that resistance genes spread to human pathogens to a much greater degree than anyone expected,” said Jan Zrimec, a researcher in systems and synthetic biology at the Chalmers University of Technology. “Many of the genes appear to have originated in a wide array of bacterial species and environments, such as soil, water, and plant bacteria.

“This has been difficult to explain because although conjugation is very common, we’ve thought that there was a distinct limitation for which bacterial species can transfer plasmids to each other. Plasmids belong to different mobility groups or MOB groups, so they can’t transfer between just any bacterial species.”

Among his developments, he has written an algorithm that can sift through substantial amounts of plasmid DNA to pick out sections of DNA which are necessary for conjugation (known as oriT regions, where the enzyme relaxase can bind to and snip out DNA). This algorithm can then sort the plasmids into groups based on their oriT regions. His new method differs from the standard one because it analyses oriT regions by their physiochemical properties instead of searching DNA for the enzyme sequence for relaxase, or the point where it can bind to. This method is less time-consuming and resource intensive than the standard one.

Previously, it was thought that a plasmid had to have both the relaxase enzyme and the oriT sequence to bind to, but a bacterial cell can have an oriT region for conjugation to occur. With his new algorithm, he has been able to explore the DNA of 4600 plasmids from different bacteria found in nature.
– There may be eight times as many oriT regions than those discovered with standard methods.
– There may be twice as many mobile plasmids as previously known.
– There also may be twice as many bacterial species with mobile plasmids as previously known.
– More than half the plasmids have an oriT group matching to an enzyme for conjugation from a plasmid that already been classified in a different MOB group. This means that they could be transferred from a different plasmid in the same cell.

The last finding suggests that there may be far greater interchange between bacteria than had been previously been believed.

“This has been a major limitation of the research field up to now,” Zrimec said. “I hope that the methods will be able to benefit large parts of the research into antibiotic resistance, which is an extremely interdisciplinary and fragmented area. The methods can be used for studies aiming to develop more effective limitations to antibiotic use, instructions for how antibiotics are to be used, and new types of substances that can prevent the spread of resistance genes at the molecular level.”

Source: News-Medical.Net

Journal information: Zrimec, J. (2021) Multiple plasmid origin‐of‐transfer regions might aid the spread of antimicrobial resistance to human pathogens. MicrobiologyOpen.doi.org/10.1002/mbo3.1129.