Tag: antibiotics

A New Clue to Disarming C. Difficile’s Toxic Weaponry

C difficile. Source: CDC

Therapeutic interventions for Clostridioides difficile infection (CDI) could make use of a glucosyltransferase domain (GTD) as an ideal molecular target, potentially yielding new, effective treatments for this deadly disease.

The study, published in Science Advancesprovided new insights into TcdB, the toxic molecular weaponry of C. difficile and its hypervirulent strains, creating an opportunity to disarm it.

CDI is the leading cause of antibiotic-associated diarrhoea and gastroenteritis-associated deaths worldwide, accounting for 500 000 cases and 29 000 deaths in the US every year and is classified by the Centers for Disease Control and Prevention as one of the top health threats. The emergence and spread of hypervirulent C. difficile strains is of global concern, resembling as it does the occurrence of new virus variants in current COVID pandemic. TcdB is one of two homologous C. difficile exotoxins, and TcdB alone is capable of causing the full spectrum of CDI diseases.

“We focused on the structure and function of TcdB’s crucial GTD, which is the toxin’s ‘warhead.’ The GTD is delivered by the toxin inside the host cells and causes most of the cytosolic damage to patients,” said corresponding author Rongsheng Jin, PhD, professor in the Department of Physiology & Biophysics at the UCI School of Medicine. “We discovered molecular mechanisms by which the GTD specifically recognises and blocks the physiological functions of the human GTPases Rho and R-Ras enzyme families that are crucial signaling molecules.”

The team also showed that the classic form of TcdB and the hypervirulent TcdB recognise their human targets in different ways, leading to distinct structural changes to the host cells caused by bacterial invasion.

“Once the GTD of TcdB is inside the cells, it is shielded by our cells and becomes inaccessible to passive immunotherapy. But our studies suggest that small molecule inhibitors could be developed to disarm the GTD, which will directly eliminate the root cause of disease symptoms and cellular damage,” Prof Jin explained. “This new strategy can potentially be integrated with and complement other CDI treatment regiments.”

Source: UCI School of Medicine

Gut Microbes and Antibiotics Impact Inflammatory Pain

C difficile. Source: CDC

A study in rats showed that gut microbiomes and antibiotic use could modulate inflammatory pain.

Published in The Journal of Pain, the study examined the impact of antibiotics on the gut microbiome and how antibiotic use can alter inflammatory pain in subjects with or without access to exercise.

According to Glenn Stevenson, Ph.D., professor of psychology within the School of Social and Behavioral Sciences, this is the first publication to assess how antibiotic-induced changes to the gut microbiome impact inflammatory pain distal to the gut (in the limbs, for example).

The study determined the effects of vancomycin on inflammatory pain-stimulated and pain-depressed behaviours in rats, which was induced with formalin. Oral vancomycin administered in drinking water attenuated pain-stimulated behaviour, and prevented formalin pain-depressed wheel running. Faecal microbiota transplantation produced a non-significant trend toward reversal of vancomycin’s effect on pain-stimulated behaviour. Vancomycin depleted Firmicutes and Bacteroidetes gut populations while partially sparing Lactobacillus species and Clostridiales. The vancomycin treatment effect was associated with an altered profile in amino acid concentrations in the gut.

The results indicate that manipulation of the gut microbiome may be one method to attenuate inflammatory pain amplitude. Additionally, results indicated that the antibiotic-induced shift in gut amino acid concentrations may be a causal mechanism for this reduction in pain.

The research for this study took four years to complete, Prof Stevenson said, adding that the link between amino acids and pain reduction is “highly novel.”

Source: University of New England

Azithromycin Protects Pregnancies in Countries with Malaria

Photo by Hush Naidoo on Unsplash

A review has found that the common antibiotic azithromycin taken during pregnancy reduces low birth weight and premature births in countries where malaria is endemic.

The systematic review of 14 studies in African and Asia, published in The Lancet EClinicalMedicine, found that azithromycin, reduced low birth weight and prematurity but didn’t lower infant deaths, infections and hospital admissions.

Azithromycin, an inexpensive antibiotic widely used to treat chest and ear infections, has been specifically used in the past in pregnancy to treat STIs and, alongside other antimalarial drugs, to prevent adverse consequences of malaria on maternal and foetal outcomes and caesarean wound infections.

Murdoch Children’s Research Institute (MCRI) researcher Dr Maeve Hume-Nixon said it was not clear whether azithromycin would improve perinatal and neonatal outcomes in non-malaria endemic settings, and the potential harm on stillbirth rates needed further investigation.

Dr Hume-Nixon said these findings emphasised the importance of similar MCRI-led research currently being done in Fiji.

“This review found that there was uncertainty about the potential benefits of this intervention on neonatal deaths, admissions and infections, and potential harmful effects on stillbirth despite biological reasons why this intervention may have benefits for these outcomes,” she said.

“Therefore, results from studies like ours underway in Fiji will help to better understand the effect of this intervention on these outcomes.”

The Bulabula MaPei study is a randomised controlled clinical trial testing if azithromycin given to women in labour, prevents maternal and infant infections.

Globally, infections account for 21% of 2.4 million neonatal deaths per year and 52% of all under-five deaths, disproportionately occurring in low- and middle-income countries.

About five million cases of pregnancy-related infections occur in mothers each year as well, resulting in 75 000 maternal deaths.

MCRI Professor Fiona Russell said the large clinical trials in Africa and Asia, along with the MCRI-led trial in Fiji, were likely to inform global policy related to maternal child health and hopefully benefit infants and mothers around the world.

“Administration of azithromycin during labour may be a cheap and simple intervention that could be used to improve neonatal death rates in low and middle-income countries, alongside strengthening of maternal child health services,” she said. “This study, together with other large clinical trials, will add to evidence for the consideration of new international maternal and child health guidelines.”

Source: Murdoch Childrens Research Institute

Bacterial Superinfections in COVID Rarer Than Expected

Only 21 percent of patients with severe pneumonia caused by SARS-CoV-2 have a documented bacterial superinfection at the time of intubation, resulting in potential overuse of antibiotics, according to new research.

Superinfection occurs when another, usually different, infection is superimposed on the initial infection. In this case, it is bacterial pneumonia during severe viral pneumonia.

Dr Wunderink and co-authors reported their findings in a study published online in the Journal of Respiratory and Critical Care Medicine, which shows that the usual clinical criteria used to diagnose bacterial pneumonia could not distinguish between those with bacterial superinfection and those with severe SARS-CoV-2 infection only.

According to the authors, there is weak evidence behind current guidelines recommending that patients with SARS-CoV-2 pneumonia receive empirical antibiotics on hospital admission for suspected bacterial superinfection. In other published clinical trials of patients with SARS-CoV-2 pneumonia, rates of superinfection pneumonia are unexpectedly low.
“More accurate assessment other than just reviewing clinical parameters is needed to enable clinicians to avoid using antibiotics in the majority of these patients, but appropriately use antibiotics in the 20-25 percent who have a bacterial infection as well,” said Dr Wunderink.

The team conducted an observational study to determine the prevalence and cause of bacterial superinfection at the time of initial intubation and the incidence and cause of subsequent bacterial ventilator-associated pneumonia (VAP) in 179 patients with severe SARS-CoV-2 pneumonia which required mechanical ventilation.

The researchers analysed 386 bronchoscopic bronchoalveolar lavage fluid samples from patients, and actual antibiotic use was compared with guideline-recommended therapy. Bacterial superinfection within 48 hours of intubation was detected in 21 percent of patients; 72 patients (44.4 percent) developed at least one VAP episode; and 15 (20.8 percent) of initial VAPs were caused by difficult-to-treat bacteria.

The authors found that in patients with severe SARS-CoV-2 pneumonia, bacterial superinfection at the time of intubation occurred in less than 25 percent of patients. Guideline-based empirical antibiotic management at the time of intubation would have resulted in antibiotic overuse.

The researchers believe that their findings have multiple implications for antibiotic guidelines: “Rapid diagnostic tests are important for helping identify suspected pneumonia in intubated patients. This can have major clinical implications because the current approach of using clinically defined risk factors for suspected methicillin-resistant staphylococcus aureus (MRSA) or pseudomonas bacteria as the cause of pneumonia still grossly overestimate the true incidence of these pathogens. In addition, the recommendation for empirical antibiotic treatment of worsening viral community-acquired pneumonia (now requiring intubation) may need to be revisited. This is not only true for SARS-CoV-2 but potentially for severe influenza as well.”

“An accurate diagnosis of suspected pneumonia allows clinicians to safely avoid or use narrow spectrum antibiotics for many patients,” Dr Wunderink added.  “While multiple interventions impact mortality in these critically ill patients, the low mortality in our study with more limited antibiotic treatment suggests that our approach was safe.”

Source: American Thoracic Society

Treatment for Women with Frequent UTIs Found Wanting

Photo by Sora Shimazaki from Pexels

Women with frequent urinary tract infections report being unhappy at perceived overuse of antibiotics by their doctors and with the limited treatment options available to them, according to a new study.

The study highlights the need to get to the cause of women’s recurrent UTIs, to come up with prevention and to avoid unnecessary antibiotics use, which can eventually lead to resistance.

“Since there’s already a common treatment for UTIs – antibiotics – many doctors don’t see a need to do anything differently,” said senior author Dr Ja-Hong Kim, an associate professor at UCLA Health. “This study really gave us insight into the patient perspective and showed us those with recurrent UTIs are dissatisfied with the current management of the condition. Continued episodes can have a major impact on their quality of life.”

More than half of women will develop a UTI at some point, and roughly 1 in 4 will have repeat infections that can last for years. Many with recurrent infections will be prescribed antibiotics frequently over their lifetime.

The researchers conducted focus groups with 29 women with recurrent UTIs, which were defined as two infections in six months or three in a year. Participants were asked about their knowledge of UTIs and prevention strategies and about treatment impact on their quality of life. Two common themes were revealed: fear and frustration.

Participants were concerned foremost about antibiotic use, with a fear of unnecessary antibiotic prescriptions and developing resistance. Some also reported antibiotic treatment for symptoms which may have signified other genitourinary conditions, like an overactive bladder.

“Other bladder diseases can cause symptoms similar to recurrent UTIs, such as urination frequency and urgency, pain with urination and blood in the urine,” Dr Kim said. “These could be signs of an overactive bladder, interstitial cystitis, kidney or bladder stones, or something more serious, like bladder cancer. As physicians, we really need to be careful about not just giving patients with these symptoms antibiotics without verifying a UTI through a positive urine culture.”

SInce diagnoses take 48 hours, women can wait days for the correct prescription. This shows the need for better diagnostic tools, Dr Kim said.

Frustration and resentment toward their medical providers for “throwing antibiotics” at them without presenting alternative options for treatment and prevention, and for not understanding their experience with UTIs. In addition, many said their physicians did not properly educate them on the potential negative impacts of antibiotics; the women instead had to rely on information from the internet, magazines and TV.

Beyond improved diagnostics, treatment approaches and guidelines, better patient education is key, Dr Kim said. “We need to do a better job of letting patients know when antibiotics are necessary and when to consider alternative therapy for bladder conditions other than UTIs.”

Dr Kim and her colleagues are currently working to improve UTI diagnosis and management, including developing comprehensive patient-care pathways through which primary care physicians and general gynecologists and urologists will provide initial UTI patient education and management. They are also pursuing studies examining the relationship of the vaginal microbiome to lower urinary tract symptoms and are working to incorporate novel diagnostic methods to allow for point-of-care treatment for UTIs.

Source: UCLA

Old Antibiotics as New Weapons against Melanoma

Researchers may have hit upon a new weapon in the fight against melanoma: antibiotics that target a vulnerability in the ‘power plants’ of cancer cells when they try to survive cancer therapy.

“As the cancer evolves, some melanoma cells may escape the treatment and stop proliferating to ‘hide’ from the immune system. These are the cells that have the potential to form a new tumor mass at a later stage,” explains cancer researcher and RNA biologist Eleonora Leucci at KU Leuven, Belgium. “In order to survive the cancer treatment however, those inactive cells need to keep their ‘power plants’—the mitochondria—switched on at all times.” As mitochondria derive from bacteria that, over time, started living inside cells, they are very vulnerable to a specific class of antibiotics. This is what gave us the idea to use these antibiotics as anti-melanoma agents.”

The researchers implanted patient-derived tumors into mice, which were then treated with antibiotics, either as alone or in combined with existing anti-melanoma therapies. Leucci observed: “The antibiotics quickly killed many cancer cells and could thus be used to buy the precious time needed for immunotherapy to kick in. In tumors that were no longer responding to targeted therapies, the antibiotics extended the lifespan of—and in some cases even cured—the mice.”

The researchers made use of nearly antibiotics rendered nearly obsolete because of antibiotic resistance. However, this does not affect the efficacy of the treatment in this study, Leucci explained. “The cancer cells show high sensitivity to these antibiotics, so we can now look to repurpose them to treat cancer instead of bacterial infections.”

However, patients with melanoma should not try to experiment, warned Leucci. “Our findings are based on research in mice, so we don’t know how effective this treatment is in human beings. Our study mentions only one human case where a melanoma patient received antibiotics to treat a bacterial infection, and this re-sensitized a resistant melanoma lesion to standard therapy. This result is cause for optimism, but we need more research and clinical studies to examine the use of antibiotics to treat cancer patients. Together with oncologist Oliver Bechter (KU Leuven/UZ Leuven), who is a co-author of this study, we are currently exploring our options.”

Source: KU Leuven

Journal information: Roberto Vendramin et al, Activation of the integrated stress response confers vulnerability to mitoribosome-targeting antibiotics in melanoma, Journal of Experimental Medicine (2021). DOI: 10.1084/jem.20210571

In Utero or Neonatal Antibiotic Exposure Could Lead to Brain Disorders

Image by Ahmad Ardity from Pixabay
Image by Ahmad Ardity from Pixabay

According to a new study, antibiotic exposure early in life could alter human brain development in areas responsible for cognitive and emotional functions.

The study suggests that penicillin alters the body’s microbiome as well as gene expression, which allows cells to respond to its changing environment, in key areas of the developing brain. The findings, published in the journal iScience, suggest reducing widespread antibiotic use or using alternatives when possible to prevent neurodevelopment problems.
Penicillin and related medicines, such as ampicillin and amoxicillin, are the most widely used antibiotics in children worldwide. In the United States, the average child receives nearly three courses of antibiotics before age 2, and similar or greater exposure rates occur elsewhere.

“Our previous work has shown that exposing young animals to antibiotics changes their metabolism and immunity. The third important development in early life involves the brain. This study is preliminary but shows a correlation between altering the microbiome and  changes in the brain that should be further explored,” said lead author Martin Blaser, director of the Center for Advanced Biotechnology and Medicine at Rutgers.

In the study, mice were exposed to low-dose penicillin in utero or immediately after birth. Researchers found that, compared to the unexposed controls, mice given penicillin had large changes in their intestinal microbiota, with altered gene expression in the frontal cortex and amygdala. These two key brain areas are responsible for the development of memory as well as fear and stress responses.

Increasing evidence links conditions in the intestine to the brain in the ‘gut-brain axis‘. If this pathway is disturbed, it can lead to permanent altering of the brain’s structure and function and possibly lead to neuropsychiatric or neurodegenerative disorders in later childhood or adulthood.

“Early life is a critical period for neurodevelopment,” Blaser said. “In recent decades, there has been a rise in the incidence of childhood neurodevelopmental disorders, including autism spectrum disorder, attention deficit/hyperactivity disorder and learning disabilities. Although increased awareness and diagnosis are likely contributing factors, disruptions in cerebral gene expression early in development also could be responsible.”

Whether it is antibiotics directly affecting brain development or if molecules from the microbiome travelling to the brain, disturbing gene activity and causing cognitive deficits needs to be determined by future studies.

Source: Rutgers University-New Brunswick

Holding off on Antibiotics is Safe and Effective for Patients

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

WHO Says New Antibiotic Treatments are Falling Behind

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

Combination Nanoparticle Therapy Shows Promise as Antiviral

Researchers have developed a new nanoparticle combination as a broad-spectrum anti-RNA virus treatment. 

The results of their study have been published on the bioRxiv preprint server. Note that as a preprint, this paper has not yet been peer reviewed.
Non-specific antivirals offer a number of attractive advantages. Their broad spectrum activity suppresses mutations, and would they also readily be at hand for future outbreaks. Nanoparticles are one possibility, with reduced toxicity.

Silver nanoparticles (AgNPs) are well-established as antibacterial and antiviral agents, and are the subject of many exotic biomedical applications. The mechanism of AgNPs is thought to be through physiochemical destruction of the microbial surface, with internal disruption from free Ag+ ions and reactive oxide species. Graphene oxide (GO) also has anti microbial properties. With its high surface area, GO also acts as a drug carrier.

The researchers produced seven different material combinations using three different methods: reduction with silver salt, direct addition of Ag nanospheres, and direct addition of Ag nanospheres to thiolised graphene.
To test the materials against seasonal-type infections as well as the kind of virus that could be expected from a future pandemic, the researchers tested the nanoparticles with influenza A virus (IAV) and human coronavirus (HCoV) OC43. IAV is an enveloped virus of the orthomyxovirus family with a segmented single-stranded RNA genome; it causes flu pandemics. HCoV-OC43 is an enveloped betacoronavirus with a single-stranded RNA genome associated with the common cold in humans.

Two of the GO-AgNP materials showed rapid, potent antiviral activity in solution against the viruses. The remaining five materials possessed a range of modest to no antiviral effects against IAV, the researchers reported. They observed a synergistic effect between the AgNPs and GO, with mechanism of action possibly being rapid disruption of the viral envelope. With high levels of antiviral agents, the combination of AgNPs with GO was found to show greater antiviral performance and lower toxicity.

“Our finding that graphene oxide/silver nanoparticle ink can rapidly prevent in vitro infection with two different viruses is exciting, and suggests that the ink has the potential to be used in a variety of applications to help reduce the spread of viruses in the environment,” said co-author Dr Meredith J Crane.

Source: News-Medical.Net

Journal information: Graphene oxide/silver nanoparticle ink formulations rapidly inhibit influenza A virus and OC43 coronavirus infection in vitro, Meredith J. Crane, Stephen Devine, Amanda M. Jamieson, bioRxiv 2021.02.25.43