scholarly journals Shooting yourself in the foot: How immune cells induce antibiotic tolerance in microbial pathogens

2021 ◽  
Vol 17 (7) ◽  
pp. e1009660
Author(s):  
Jenna E. Beam ◽  
Sarah E. Rowe ◽  
Brian P. Conlon
Keyword(s):  
Treatment Failure ◽  
Cell Activity ◽  
Resistance Mechanisms ◽  
Microbial Pathogens ◽  
Antibiotic Tolerance ◽  
Phagocytic Cells ◽  
Immune Mediated ◽  
Antibiotic Failure ◽  
Phenotypic State ◽  
Tolerant State

Antibiotic treatment failure of infection is common and frequently occurs in the absence of genetically encoded antibiotic resistance mechanisms. In such scenarios, the ability of bacteria to enter a phenotypic state that renders them tolerant to the killing activity of multiple antibiotic classes is thought to contribute to antibiotic failure. Phagocytic cells, which specialize in engulfing and destroying invading pathogens, may paradoxically contribute to antibiotic tolerance and treatment failure. Macrophages act as reservoirs for some pathogens and impede penetration of certain classes of antibiotics. In addition, increasing evidence suggests that subpopulations of bacteria can survive inside these cells and are coerced into an antibiotic-tolerant state by host cell activity. Uncovering the mechanisms that drive immune-mediated antibiotic tolerance may present novel strategies to improving antibiotic therapy.

scholarly journals The novel Dbl homology/BAR domain protein, MsgA, of Talaromyces marneffei regulates yeast morphogenesis during growth inside host cells

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Harshini Weerasinghe ◽  
Hayley E. Bugeja ◽  
Alex Andrianopoulos
Keyword(s):  
Pathogenic Fungi ◽  
Host Cells ◽  
Microbial Pathogens ◽  
Mammalian Host ◽  
Host Immune System ◽  
Nucleotide Exchange ◽  
Phagocytic Cells ◽  
Macrophage Infection ◽  
Bar Domain ◽  
Talaromyces Marneffei

AbstractMicrobial pathogens have evolved many strategies to evade recognition by the host immune system, including the use of phagocytic cells as a niche within which to proliferate. Dimorphic pathogenic fungi employ an induced morphogenetic transition, switching from multicellular hyphae to unicellular yeast that are more compatible with intracellular growth. A switch to mammalian host body temperature (37 °C) is a key trigger for the dimorphic switch. This study describes a novel gene, msgA, from the dimorphic fungal pathogen Talaromyces marneffei that controls cell morphology in response to host cues rather than temperature. The msgA gene is upregulated during murine macrophage infection, and deletion results in aberrant yeast morphology solely during growth inside macrophages. MsgA contains a Dbl homology domain, and a Bin, Amphiphysin, Rvs (BAR) domain instead of a Plekstrin homology domain typically associated with guanine nucleotide exchange factors (GEFs). The BAR domain is crucial in maintaining yeast morphology and cellular localisation during infection. The data suggests that MsgA does not act as a canonical GEF during macrophage infection and identifies a temperature independent pathway in T. marneffei that controls intracellular yeast morphogenesis.

scholarly journals 1342. Clinical failure rates of amoxicillin for the treatment of acute otitis media in young children

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S682-S683
Author(s):  
Holly M Frost ◽  
Samuel Dominguez ◽  
Sarah Parker ◽  
Andrew Byars ◽  
Sara Michelson ◽  
...  
Keyword(s):  
Treatment Failure ◽  
Otitis Media ◽  
Failure Rate ◽  
Acute Otitis Media ◽  
Relative Reduction ◽  
Failure Rates ◽  
Beta Lactamase ◽  
Clinical Failure ◽  
Recurrence Rates ◽  
Antibiotic Failure

Abstract Background Acute otitis media(AOM) is the most common indication for antibiotics in children. The primary pathogens that cause AOM have changed since the introduction of the pneumococcal conjugate vaccine(PCV). The clinical failure rate of amoxicillin for treatment of AOM post-PCV is unknown.We aimed to determine the clinical failure rate of amoxicillin for the treatment of uncomplicated AOM in children. Organisms identified on culture and amoxicillin treatment failure from nasopharyngeal specimens of children age 6-35 months with uncomplicated acute otitis media at Denver Health, Denver, CO from April 2019-March 2020. Methods Children age 6-35 months seen at Denver Health, Denver, CO with uncomplicated AOM and prescribed amoxicillin were prospectively enrolled. An interim analysis of patients enrolled from April 2019-March 2020 was completed. Patients completed surveys that included the AOM-SOS©(UPMC, Pittsburgh, PA) at enrollment, days 5, 14, and 30 and had chart abstraction completed. Treatment failure was defined as: (1) requiring a new antibiotic within 14 days; (2) AOM-SOS© score on day 5 or 14 not improved by a relative reduction of ≥ 55% from baseline. Recurrence was defined as requiring a new antibiotic within 15-30 days. Nasopharyngeal swabs were obtained and bacterial culture was completed. Results In total,110 patients were enrolled. Rates of treatment failure defined by AOM-SOS© were 28.4%(37; 95%CI:25.5-33.6%) at 5 days and 15.5%(27; 95%CI:17.5-24.5%) at 14 days. However, only 4.5%(5; 95%CI:2.0-4.5%) required a new antibiotic. Recurrence occurred in 5.5% (6, 95%CI:2.5-5.5%) of patients. Of patients who had not received antibiotics before enrollment(82), culture yielded no organism in 17.0%, one organism in 42.7%, and multiple organisms in 40.0% (Table). M.catarrhalis was the most frequently identified organism (53.7% of children). Of H.influenzae isolates 52.9% (9/17) produced beta-lactamase, resulting in no treatment failures or recurrences requiring a new antibiotic. Failure rates were similar between organisms. Conclusion Despite the change in otopathogen prevalence post-PCV, preliminary data suggest that while early subjective treatment failure was common, the 14 day treatment failure and 30 day recurrence rates was low when measured by need for a new antibiotic. Failure was low even among patients with organisms that would not be expected to be treated successfully with amoxicillin, such as those with beta-lactamase producing H.influenzae and M.catarrhalis. Disclosures Samuel Dominguez, MD, PhD, BioFire (Consultant, Research Grant or Support)

scholarly journals Isolation and primary culture of Galleria mellonella hemocytes for infection studies

F1000Research ◽  
2021 ◽  
Vol 9 ◽  
pp. 1392
Author(s):  
Nicola J. Senior ◽  
Richard W. Titball
Keyword(s):  
Primary Culture ◽  
Alternative Model ◽  
Galleria Mellonella ◽  
Microbial Pathogens ◽  
Needle Stick Injury ◽  
Antimicrobial Compounds ◽  
Phagocytic Cells ◽  
Needle Stick ◽  
Research Institutes ◽  
Pre Treatment

Galleria mellonella larvae are increasingly used to study the mechanisms of virulence of microbial pathogens and to assess the efficacy of antimicrobials.  The G. mellonella model can faithfully reproduce many aspects of microbial disease which are seen in mammals, and therefore allows a reduction in the use of mammals. The model is now being widely used by researchers in universities, research institutes and industry. An attraction of the model is the interaction between pathogen and host. Hemocytes are specialised phagocytic cells which resemble neutrophils in mammals and play a major role in the response of the larvae to infection. However, the detailed interactions of hemocytes with pathogens is poorly understood, and is complicated by the presence of different sub-populations of cells. We report here a method for the isolation of hemocytes from Galleria mellonella.  A needle-stick injury of larvae, before harvesting, markedly increased the recovery of hemocytes in the hemolymph. The majority of the hemocytes recovered were granulocyte-like cells. The hemocytes survived for at least 7 days in culture at either 28°C or 37°C. Pre-treatment of larvae with antibiotics did not enhance the survival of the cultured hemocytes. Our studies highlight the importance of including sham injected, rather than un-injected, controls when the G. mellonella model is used to test antimicrobial compounds. Our method will now allow investigations of the interactions of microbial pathogens with insect hemocytes enhancing the value of G. mellonella as an alternative model to replace the use of mammals, and for studies on hemocyte biology.

scholarly journals Serial liquid biopsies for detection of treatment failure and profiling of resistance mechanisms in KLC1–ALK-rearranged lung cancer

2019 ◽  
Vol 5 (6) ◽  
pp. a004630 ◽  
Author(s):  
Steffen Dietz ◽  
Petros Christopoulos ◽  
Lisa Gu ◽  
Anna-Lena Volckmar ◽  
Volker Endris ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Treatment Failure ◽  
Resistance Mechanisms ◽  
Liquid Biopsies

scholarly journals Antibiotic Treatment Failure and Associated Outcomes Among Adult Patients With Community-Acquired Pneumonia in the Outpatient Setting: A Real-world US Insurance Claims Database Study

2020 ◽  
Vol 7 (3) ◽  
Author(s):  
Glenn Tillotson ◽  
Thomas Lodise ◽  
Peter Classi ◽  
Donna Mildvan ◽  
James A McKinnell
Keyword(s):  
Health Care ◽  
Treatment Failure ◽  
Antibiotic Treatment ◽  
Health Care Costs ◽  
Outpatient Setting ◽  
Community Acquired Pneumonia ◽  
Failure Group ◽  
Antibiotic Failure ◽  
Care Costs ◽  
Experienced Treatment

Abstract Background Antibiotic treatment failure is common among patients with community-acquired pneumonia (CAP) who are managed in the outpatient setting and is associated with higher mortality and increased health care costs. This study’s objectives were to quantify the occurrence of antibiotic treatment failure (ATF) and to evaluate clinical and economic outcomes between CAP patients who experienced ATF relative to those who did not. Methods Retrospective analysis of the MarketScan Commercial & Medicare Supplemental Databases was performed, identifying patients ≥18 years old, with a pneumonia diagnosis in the outpatient setting, and who received a fluoroquinolone, macrolides, beta-lactam, or tetracycline. ATF was defined as any of the following events within 30 days of initial antibiotic: antibiotic refill, antibiotic switch, emergency room visit, or hospitalization. Outcomes included 30-day all-cause mortality and CAP-related health care costs. Results During the study period, 251 947 unique patients met inclusion criteria. The mean age was 52.2 years, and 47.7% were male. The majority of patients received a fluoroquinolone (44.4%) or macrolide (43.6%). Overall, 22.1% were classified as ATFs. Among 18–64-year-old patients, 21.2% experienced treatment failure, compared with 25.7% in those >65 years old. All-cause mortality was greater in the antibiotic failure group relative to the non–antibiotic failure group (18.1% vs 4.6%, respectively), and the differences in 30-day mortality between antibiotic failure groups increased as a function of age. Mean 30-day CAP-related health care costs were also higher in the patients who experienced treatment failure relative to those who did not ($2140 vs $54, respectively). Conclusions Treatment failure and poor outcomes from outpatient CAP are common with current guideline-concordant CAP therapies. Improvements in clinical management programs and therapeutic options are needed.

scholarly journals Antifungal Resistance Regarding Malassezia pachydermatis: Where Are We Now?

2020 ◽  
Vol 6 (2) ◽  
pp. 93
Author(s):  
Andrea Peano ◽  
Elizabeth Johnson ◽  
Elisa Chiavassa ◽  
Paolo Tizzani ◽  
Jacques Guillot ◽  
...  
Keyword(s):  
Treatment Failure ◽  
Antifungal Agents ◽  
Standard Procedure ◽  
Resistance Mechanisms ◽  
Antifungal Resistance ◽  
Antifungal Drugs ◽  
Malassezia Pachydermatis ◽  
Development Of Resistance ◽  
Ear Canals

Malassezia pachydermatis is a yeast inhabiting the skin and ear canals in healthy dogs. In the presence of various predisposing conditions it can cause otitis and dermatitis, which are treated with multiple antifungal agents, mainly azole derivatives. This manuscript aims to review the available evidence regarding the occurrence of resistance phenomena in this organism. Various findings support the capacity of M. pachydermatis for developing resistance. These include some reports of treatment failure in dogs, the reduced antifungal activity found against yeast isolates sampled from dogs with exposure to antifungal drugs and strains exposed to antifungal agents in vitro, and the description of resistance mechanisms. At the same time, the data reviewed may suggest that the development of resistance is a rare eventuality in canine practice. For example, only three publications describe confirmed cases of treatment failure due to antifungal resistance, and most claims of resistance made by past studies are based on interpretive breakpoints that lack sound support from the clinical perspective. However, it is possible that resistant cases are underreported in literature, perhaps due to the difficulty of obtaining a laboratory confirmation given that a standard procedure for susceptibility testing of M. pachydermatis is still unavailable. These considerations highlight the need for maintaining surveillance for the possible emergence of clinically relevant resistance, hopefully through a shared strategy put in place by the scientific community.

scholarly journals The Arginine Deiminase Pathway Impacts Antibiotic Tolerance during Biofilm-Mediated Streptococcus pyogenes Infections

mBio ◽  
2020 ◽  
Vol 11 (4) ◽  
Author(s):  
Jeffrey A. Freiberg ◽  
Yoann Le Breton ◽  
Janette M. Harro ◽  
Devon L. Allison ◽  
Kevin S. McIver ◽  
...  
Keyword(s):  
Treatment Failure ◽  
Antibiotic Treatment ◽  
Streptococcus Pyogenes ◽  
Bacterial Infections ◽  
Bacterial Species ◽  
Arginine Deiminase ◽  
Antibiotic Tolerance ◽  
Human Pathogen ◽  
Biofilm Growth ◽  
Content Type

ABSTRACT Bacterial biofilms are responsible for a variety of serious human infections and are notoriously difficult to treat due to their recalcitrance to antibiotics. Further work is necessary to elicit a full understanding of the mechanism of this antibiotic tolerance. The arginine deiminase (ADI) pathway is responsible for bacterial pH maintenance and is highly expressed during biofilm growth in multiple bacterial species. Using the group A Streptococcus (GAS) as a model human pathogen, the ADI pathway was demonstrated to contribute to biofilm growth. The inability of antibiotics to reduce GAS populations when in a biofilm was demonstrated by in vitro studies and a novel animal model of nasopharyngeal infection. However, disruption of the ADI pathway returned GAS biofilms to planktonic levels of antibiotic sensitivity, suggesting the ADI pathway is influential in biofilm-related antibiotic treatment failure and provides a new strategic target for the treatment of biofilm infections in GAS and potentially numerous other bacterial species. IMPORTANCE Biofilm-mediated bacterial infections are a major threat to human health because of their recalcitrance to antibiotic treatment. Through the study of Streptococcus pyogenes, a significant human pathogen that is known to form antibiotic-tolerant biofilms, we demonstrated the role that a bacterial pathway known for responding to acid stress plays in biofilm growth and antibiotic tolerance. This not only provides some insight into antibiotic treatment failure in S. pyogenes infections but also, given the widespread nature of this pathway, provides a potentially broad target for antibiofilm therapies. This discovery has the potential to impact the treatment of many different types of recalcitrant biofilm infections.

scholarly journals LXR-inverse agonism stimulates immune-mediated tumor destruction by enhancing CD8 T-cell activity in triple negative breast cancer

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Katherine J. Carpenter ◽  
Aurore-Cecile Valfort ◽  
Nick Steinauer ◽  
Arindam Chatterjee ◽  
Suomia Abuirqeba ◽  
...  
Keyword(s):  
Breast Cancer ◽  
T Cell ◽  
Triple Negative Breast Cancer ◽  
Triple Negative ◽  
Immune Cell ◽  
Cell Activity ◽  
Cd8 T Cell ◽  
Tumor Immune Evasion ◽  
Tumor Destruction ◽  
Immune Mediated

AbstractTriple-negative breast cancer (TNBC) is a highly aggressive subtype that is untreatable with hormonal or HER2-targeted therapies and is also typically unresponsive to checkpoint-blockade immunotherapy. Within the tumor microenvironment dysregulated immune cell metabolism has emerged as a key mechanism of tumor immune-evasion. We have discovered that the Liver-X-Receptors (LXRα and LXRβ), nuclear receptors known to regulate lipid metabolism and tumor-immune interaction, are highly activated in TNBC tumor associated myeloid cells. We therefore theorized that inhibiting LXR would induce immune-mediated TNBC-tumor clearance. Here we show that pharmacological inhibition of LXR activity induces tumor destruction primarily through stimulation of CD8+ T-cell cytotoxic activity and mitochondrial metabolism. Our results imply that LXR inverse agonists may be a promising new class of TNBC immunotherapies.

scholarly journals Reduced Vancomycin Susceptibility in Staphylococcus aureus, Including Vancomycin-Intermediate and Heterogeneous Vancomycin-Intermediate Strains: Resistance Mechanisms, Laboratory Detection, and Clinical Implications

2010 ◽  
Vol 23 (1) ◽  
pp. 99-139 ◽  
Author(s):  
Benjamin P. Howden ◽  
John K. Davies ◽  
Paul D. R. Johnson ◽  
Timothy P. Stinear ◽  
M. Lindsay Grayson
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Wall ◽  
Treatment Failure ◽  
Treatment Outcomes ◽  
Susceptibility Testing ◽  
Point Mutations ◽  
Resistance Mechanisms ◽  
Wall Thickening ◽  
Clinical Implications ◽  
The Past

SUMMARY The emergence of vancomycin-intermediate Staphylococcus aureus (VISA) and heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) over the past decade has provided a challenge to diagnostic microbiologists to detect these strains, clinicians treating patients with infections due to these strains, and researchers attempting to understand the resistance mechanisms. Recent data show that these strains have been detected globally and in many cases are associated with glycopeptide treatment failure; however, more rigorous clinical studies are required to clearly define the contribution of hVISA to glycopeptide treatment outcomes. It is now becoming clear that sequential point mutations in key global regulatory genes contribute to the hVISA and VISA phenotypes, which are associated predominately with cell wall thickening and restricted vancomycin access to its site of activity in the division septum; however, the phenotypic features of these strains can vary because the mutations leading to resistance can vary. Interestingly, changes in the staphylococcal surface and expression of agr are likely to impact host-pathogen interactions in hVISA and VISA infections. Given the subtleties of vancomycin susceptibility testing against S. aureus, it is imperative that diagnostic laboratories use well-standardized methods and have a framework for detecting reduced vancomycin susceptibility in S. aureus.

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