scholarly journals Induction of the Chlamydia muridarum Stress/Persistence Response Increases Azithromycin Treatment Failure in a Murine Model of Infection

2013 ◽  
Vol 58 (3) ◽  
pp. 1782-1784 ◽  
Author(s):  
R. Phillips-Campbell ◽  
J. Kintner ◽  
R. V. Schoborg
Keyword(s):  
Stressed State ◽  
Treatment Failure ◽  
Murine Model ◽  
Developmental Cycle ◽  
Content Type ◽  
Persistently Infected ◽  
Chlamydia Muridarum

ABSTRACTViable but noninfectious (stressed/persistent) chlamydiae are more resistant to azithromycin (AZM) in culture than are organisms in the normal developmental cycle.Chlamydia muridarum-infected mice were exposed to amoxicillin to induce the organisms to enter the persistent/stressed state and subsequently treated with AZM. AZM treatment failure was observed in 22% of persistently infected mice, with an average of 321,667 inclusion-forming units (IFU) shed after AZM treatment. Productively infected mice had a 9% rate of AZM treatment failure and shed an average of 12,083 IFU. These data suggest that stressed chlamydiae are more resistant to frontline antichlamydial drugsin vivo.

scholarly journals In VivoUltrastructural Analysis of the Intimate Relationship between Polymorphonuclear Leukocytes and the Chlamydial Developmental Cycle

2011 ◽  
Vol 79 (8) ◽  
pp. 3291-3301 ◽  
Author(s):  
Roger G. Rank ◽  
Judy Whittimore ◽  
Anne K. Bowlin ◽  
Priscilla B. Wyrick
Keyword(s):  
Polymorphonuclear Leukocytes ◽  
Ultrastructural Level ◽  
Developmental Cycle ◽  
Content Type ◽  
Chlamydia Muridarum ◽  
Direct Invasion ◽  
Reticulate Body ◽  
Infected Cells

ABSTRACTWe utilized a recently developed model of intracervical infection withChlamydia muridarumin the mouse to elicit a relatively synchronous infection during the initial developmental cycle in order to examine at the ultrastructural level the development of both the chlamydial inclusion and the onset of the inflammatory response. At 18 h after infection, only a few elementary bodies attached to cells were visible, as were an occasional intracellular intermediate body and reticulate body. By 24 h, inclusions had 2 to 5 reticulate bodies and were beginning to fuse. A few polymorphonuclear leukocytes (PMNs) were already present in the epithelium in the vicinity of and directly adjacent to infected cells. By 30 h, the inclusions were larger and consisted solely of reticulate bodies, but by 36 to 42 h, they contained intermediate bodies and elementary bodies as well. Many PMNs were adjacent to or actually inside infected cells. Chlamydiae appeared to exit the cell either (i) through disintegration of the inclusion membrane and rupture of the cell, (ii) by dislodgement of the cell from the epithelium by PMNs, or (iii) by direct invasion of the infected cell by the PMNs. When PMNs were depleted, the number of released elementary bodies was significantly greater as determined both visually and by culture. Interestingly, depletion of PMNs revealed the presence of inclusions containing aberrant reticulate bodies, reminiscent of effects seenin vitrowhen chlamydiae are incubated with gamma interferon.In vivoevidence for the contact-dependent development hypothesis, a potential mechanism for triggering the conversion of reticulate bodies to elementary bodies, and for translocation of lipid droplets into the inclusion is also presented.

scholarly journals Experimental Evolution In Vivo To Identify Selective Pressures during Pneumococcal Colonization

mSystems ◽  
2020 ◽  
Vol 5 (3) ◽  
Author(s):  
Vaughn S. Cooper ◽  
Erin Honsa ◽  
Hannah Rowe ◽  
Christopher Deitrick ◽  
Amy R. Iverson ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Murine Model ◽  
Experimental Evolution ◽  
Nasal Colonization ◽  
Content Type ◽  
Selective Pressures ◽  
Specific Tissue ◽  
Tissue Tropisms ◽  
Insight Into

ABSTRACT Experimental evolution is a powerful technique to understand how populations evolve from selective pressures imparted by the surrounding environment. With the advancement of whole-population genomic sequencing, it is possible to identify and track multiple contending genotypes associated with adaptations to specific selective pressures. This approach has been used repeatedly with model species in vitro, but only rarely in vivo. Herein we report results of replicate experimentally evolved populations of Streptococcus pneumoniae propagated by repeated murine nasal colonization with the aim of identifying gene products under strong selection as well as the population genetic dynamics of infection cycles. Frameshift mutations in one gene, dltB, responsible for incorporation of d-alanine into teichoic acids on the bacterial surface, evolved repeatedly and swept to high frequency. Targeted deletions of dltB produced a fitness advantage during initial nasal colonization coupled with a corresponding fitness disadvantage in the lungs during pulmonary infection. The underlying mechanism behind the fitness trade-off between these two niches was found to be enhanced adherence to respiratory cells balanced by increased sensitivity to host-derived antimicrobial peptides, a finding recapitulated in the murine model. Additional mutations that are predicted to affect trace metal transport, central metabolism, and regulation of biofilm production and competence were also selected. These data indicate that experimental evolution can be applied to murine models of pathogenesis to gain insight into organism-specific tissue tropisms. IMPORTANCE Evolution is a powerful force that can be experimentally harnessed to gain insight into how populations evolve in response to selective pressures. Herein we tested the applicability of experimental evolutionary approaches to gain insight into how the major human pathogen Streptococcus pneumoniae responds to repeated colonization events using a murine model. These studies revealed the population dynamics of repeated colonization events and demonstrated that in vivo experimental evolution resulted in highly reproducible trajectories that reflect the environmental niche encountered during nasal colonization. Mutations impacting the surface charge of the bacteria were repeatedly selected during colonization and provided a fitness benefit in this niche that was counterbalanced by a corresponding fitness defect during lung infection. These data indicate that experimental evolution can be applied to models of pathogenesis to gain insight into organism-specific tissue tropisms.

scholarly journals Efficacy of Bacteriophages in a Staphylococcus aureus Nondiabetic or Diabetic Foot Infection Murine Model

2019 ◽  
Vol 64 (2) ◽  
Author(s):  
S. Albac ◽  
M. Medina ◽  
D. Labrousse ◽  
D. Hayez ◽  
D. Bonnot ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Mouse Models ◽  
Murine Model ◽  
Phage Therapy ◽  
Single Injection ◽  
Antibacterial Efficacy ◽  
Content Type ◽  
Diabetic Foot Infection ◽  
Preclinical And Clinical Studies

ABSTRACT This study investigated the in vivo efficacy of three bacteriophages combined compared with linezolid in two mouse models (nondiabetic and diabetic) of Staphylococcus aureus foot infection. In both models, a single injection of bacteriophages in the hindpaw showed significant antibacterial efficacy. Linezolid was as effective as bacteriophages in nondiabetic animals but ineffective in diabetic animals. These findings further support preclinical and clinical studies for the development of phage therapy.

scholarly journals Efficacy of Humanized High-Dose Meropenem, Cefepime, and Levofloxacin against Enterobacteriaceae Isolates Producing Verona Integron-Encoded Metallo-β-Lactamase (VIM) in a Murine Thigh Infection Model

2015 ◽  
Vol 59 (11) ◽  
pp. 7145-7147 ◽  
Author(s):  
Islam M. Ghazi ◽  
Jared L. Crandon ◽  
Emil P. Lesho ◽  
Patrick McGann ◽  
David P. Nicolau
Keyword(s):  
Murine Model ◽  
Infection Model ◽  
High Dose ◽  
Content Type ◽  
High Mics

ABSTRACTWe aimed to describe thein vivoactivity of humanized pharmacokinetic exposures of meropenem and comparators against Verona integron-encoded metallo-β-lactamase (MBL) (VIM)-producingEnterobacteriaceaein a murine model. Levofloxacin activity was predicted by its MIC, and cefepime activity displayed variability, whereas meropenem produced a >1 log CFU reduction against all isolates despite high MICs indicative of resistance. Our results suggest that despitein vitroresistance, high-dose meropenem may be a possible option against infections caused byEnterobacteriaceaeproducing MBL-type carbapenemases.

scholarly journals Enantiomers of Nifurtimox Do Not Exhibit Stereoselective Anti-Trypanosoma cruzi Activity, Toxicity, or Pharmacokinetic Properties

2015 ◽  
Vol 59 (6) ◽  
pp. 3645-3647 ◽  
Author(s):  
Carolina B. Moraes ◽  
Karen L. White ◽  
Stéphanie Braillard ◽  
Catherine Perez ◽  
Junghyun Goo ◽  
...  
Keyword(s):  
Trypanosoma Cruzi ◽  
Chagas Disease ◽  
Murine Model ◽  
Therapeutic Benefit ◽  
Racemic Mixture ◽  
Content Type ◽  
Pharmacokinetic Properties

ABSTRACTWith the aim of improving the available drugs for the treatment of Chagas disease, individual enantiomers of nifurtimox were characterized. The results indicate that the enantiomers are equivalent in theirin vitroactivity against a panel ofTrypanosoma cruzistrains;in vivoefficacy in a murine model of Chagas disease;in vitrotoxicity and absorption, distribution, metabolism, and excretion characteristics; andin vivopharmacokinetic properties. There is unlikely to be any therapeutic benefit of an individual nifurtimox enantiomer over the racemic mixture.

scholarly journals Physiologic Expression of the Candida albicans Pescadillo Homolog Is Required for Virulence in a Murine Model of Hematogenously Disseminated Candidiasis

2012 ◽  
Vol 11 (12) ◽  
pp. 1552-1556 ◽  
Author(s):  
Priya Uppuluri ◽  
Ashok K. Chaturvedi ◽  
Niketa Jani ◽  
Read Pukkila-Worley ◽  
Carlos Monteagudo ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Murine Model ◽  
Critical Role ◽  
Growth Defect ◽  
Mammalian Host ◽  
Developmental Cycle ◽  
Yeast Growth ◽  
Content Type ◽  
Disseminated Candidiasis

ABSTRACT Morphogenetic conversions contribute to the pathogenesis of Candida albicans invasive infections. Many studies to date have convincingly demonstrated a link between filamentation and virulence; however, relatively little is known regarding the role of the filament-to-yeast transition during the pathogenesis of invasive candidiasis. We previously identified the C. albicans pescadillo homolog ( PES1 ) as essential during yeast growth and growth of lateral yeast on hyphae but not during hyphal growth. Furthermore, we demonstrated that PES1 is required for virulence in vivo in a Galleria mellonella larva model of candidiasis. Here, we have used a regulatable tetO-PES1 / pes1 strain to assess the contribution of C. albicans PES1 to pathogenesis in the commonly used and clinically relevant murine model of hematogenously disseminated candidiasis. Our results indicate that a physiologically controlled level of PES1 expression is required for full virulence in this animal model, with virulence defects observed both when PES1 is overexpressed and and when it is depleted. The pathogenetic defect of cells depleted of PES1 is not due to a general growth defect, as demonstrated by the fact that PES1 -depleted cells still kill Caenorhabditis elegans as efficiently as the wild type due to hyphal outgrowth through worm tissues. Our results suggest a critical role of lateral yeast growth in the ability of C. albicans to normally proliferate within tissues, as well as a pivotal role for Pes1 in the normal developmental cycle of C. albicans within the mammalian host during infection.

scholarly journals Macrolones Are a Novel Class of Macrolide Antibiotics Active against Key Resistant Respiratory PathogensIn VitroandIn Vivo

2016 ◽  
Vol 60 (9) ◽  
pp. 5337-5348 ◽  
Author(s):  
Hana Čipčić Paljetak ◽  
Donatella Verbanac ◽  
Jasna Padovan ◽  
Miroslava Dominis-Kramarić ◽  
Željko Kelnerić ◽  
...  
Keyword(s):  
Murine Model ◽  
Bacterial Resistance ◽  
Volume Of Distribution ◽  
Macrolide Antibiotics ◽  
Respiratory Pathogens ◽  
Protein Synthesis Inhibitors ◽  
Content Type ◽  
Tract Infections

ABSTRACTAs we face an alarming increase in bacterial resistance to current antibacterial chemotherapeutics, expanding the available therapeutic arsenal in the fight against resistant bacterial pathogens causing respiratory tract infections is of high importance. The antibacterial potency of macrolones, a novel class of macrolide antibiotics, against key respiratory pathogens was evaluatedin vitroandin vivo. MIC values againstStreptococcus pneumoniae,Streptococcus pyogenes,Staphylococcus aureus, andHaemophilus influenzaestrains sensitive to macrolide antibiotics and with defined macrolide resistance mechanisms were determined. The propensity of macrolones to induce the expression of inducibleermgenes was tested by the triple-disk method and incubation in the presence of subinhibitory concentrations of compounds.In vivoefficacy was assessed in a murine model ofS. pneumoniae-induced pneumonia, and pharmacokinetic (PK) profiles in mice were determined. Thein vitroantibacterial profiles of macrolones were superior to those of marketed macrolide antibiotics, including the ketolide telithromycin, and the compounds did not induce the expression of inducibleermgenes. They acted as typical protein synthesis inhibitors in anEscherichia colitranscription/translation assay. Macrolones were characterized by low to moderate systemic clearance, a large volume of distribution, a long half-life, and low oral bioavailability. They were highly efficacious in a murine model of pneumonia after intraperitoneal application even against anS. pneumoniaestrain with constitutive resistance to macrolide-lincosamide-streptogramin B antibiotics. Macrolones are the class of macrolide antibiotics with an outstanding antibacterial profile and reasonable PK parameters resulting in goodin vivoefficacy.

scholarly journals Streptococcus pyogenes Arginine and Citrulline Catabolism Promotes Infection and Modulates Innate Immunity

2013 ◽  
Vol 82 (1) ◽  
pp. 233-242 ◽  
Author(s):  
Zachary T. Cusumano ◽  
Michael E. Watson ◽  
Michael G. Caparon
Keyword(s):  
Nitric Oxide ◽  
Innate Immunity ◽  
Streptococcus Pyogenes ◽  
Murine Model ◽  
Acid Stress ◽  
Arginine Deiminase ◽  
Content Type ◽  
Cutaneous Tissue

ABSTRACTA bacterium's ability to acquire nutrients from its host during infection is an essential component of pathogenesis. For the Gram-positive pathogenStreptococcus pyogenes, catabolism of the amino acid arginine via the arginine deiminase (ADI) pathway supplements energy production and provides protection against acid stressin vitro. Its expression is enhanced in murine models of infection, suggesting an important rolein vivo. To gain insight into the function of the ADI pathway in pathogenesis, the virulence of mutants defective in each of its enzymes was examined. Mutants unable to use arginine (ΔArcA) or citrulline (ΔArcB) were attenuated for carriage in a murine model of asymptomatic mucosal colonization. However, in a murine model of inflammatory infection of cutaneous tissue, the ΔArcA mutant was attenuated but the ΔArcB mutant was hyperattenuated, revealing an unexpected tissue-specific role for citrulline metabolism in pathogenesis. When mice defective for the arginine-dependent production of nitric oxide (iNOS−/−) were infected with the ΔArcA mutant, cutaneous virulence was rescued, demonstrating that the ability ofS. pyogenesto utilize arginine was dispensable in the absence of nitric oxide-mediated innate immunity. This work demonstrates the importance of arginine and citrulline catabolism and suggests a novel mechanism of virulence by whichS. pyogenesuses its metabolism to modulate innate immunity through depletion of an essential host nutrient.

scholarly journals Efficacy of Delayed Therapy with Fosmanogepix (APX001) in a Murine Model of Candida auris Invasive Candidiasis

2019 ◽  
Vol 63 (11) ◽  
Author(s):  
Nathan P. Wiederhold ◽  
Laura K. Najvar ◽  
Karen J. Shaw ◽  
Rosie Jaramillo ◽  
Hoja Patterson ◽  
...  
Keyword(s):  
Murine Model ◽  
Invasive Candidiasis ◽  
Pathogenic Fungi ◽  
Candida Auris ◽  
Pathogenic Yeast ◽  
Once Daily ◽  
Content Type ◽  
Fungal Burden ◽  
Fluconazole Resistant

ABSTRACT The emerging pathogenic yeast Candida auris is associated with antifungal resistance and high mortality. The novel antifungal agent manogepix (APX001A) inhibits glycosylphosphatidylinositol-anchored protein maturation and has demonstrated activity against numerous pathogenic fungi, including C. auris. Our objective was to evaluate the in vivo efficacy of fosmanogepix, the N-phosphonooxymethyl prodrug (APX001), following delayed initiation of therapy in a murine model of C. auris invasive candidiasis. Neutropenic mice were intravenously infected with a fluconazole-resistant clinical isolate of C. auris. Twenty-four hours postinoculation, treatment began with vehicle control, fosmanogepix (104 and 130 mg/kg of body weight by intraperitoneal injection three times daily, or intraperitoneal 260 mg/kg twice daily), fluconazole (20 mg/kg by oral gavage once daily), or caspofungin (intraperitoneal 10 mg/kg once daily) and continued for 7 days. Fungal burden was assessed via colony count in the kidneys and brains on day 8 in the fungal burden arm and on day 21 as the mice became moribund in the survival arm. Significant improvements in survival were observed in each group administered fosmanogepix and caspofungin. Similarly, reductions in fungal burden were also observed in both the kidneys and brains of mice treated with the highest dose of fosmanogepix in the fungal burden arm and in each fosmanogepix group and with caspofungin in the survival arm. In contrast, no improvements in survival or reductions in fungal burden were observed in mice treated with fluconazole. These results demonstrate that fosmanogepix is effective in vivo against fluconazole-resistant C. auris even when therapy is delayed.

scholarly journals Enhanced Neutrophil Longevity and Recruitment Contribute to the Severity of Oviduct Pathology during Chlamydia muridarum Infection

2011 ◽  
Vol 79 (10) ◽  
pp. 4029-4041 ◽  
Author(s):  
Lauren C. Frazer ◽  
Catherine M. O'Connell ◽  
Charles W. Andrews ◽  
Matthew A. Zurenski ◽  
Toni Darville
Keyword(s):  
Cytokine Production ◽  
Acute Infection ◽  
Absolute Number ◽  
Neutrophil Apoptosis ◽  
Content Type ◽  
Chlamydia Muridarum ◽  
Reduced Frequency

ABSTRACTOur previous studies revealed that intravaginal infection of mice with a plasmid-deficient strain ofChlamydia muridarum, CM3.1, does not induce the development of oviduct pathology. In this study, we determined that infection with CM3.1 resulted in a significantly reduced frequency and absolute number of neutrophils in the oviducts during acute infection. This reduction in neutrophils was associated with significantly lower levels of neutrophil chemokines in the oviducts and decreased production of neutrophil chemokines by oviduct epithelial cells infected with CM3.1in vitro. Infection with CM3.1 also resulted in an increased frequency of late apoptotic/dead neutrophils in the oviduct. Examination of the ability ofChlamydia trachomatisto prevent neutrophil apoptosisin vitrorevealed thatC. trachomatisstrain D/UW-3/Cx exhibited an enhanced ability to prevent neutrophil apoptosis compared to plasmid-deficient CTD153, and this effect was dependent on the presence of CD14highmonocytes. The presence of monocytes also resulted in enhanced neutrophil cytokine production and increased production of tissue-damaging molecules in response to D/UW-3/Cx relative to results with CTD153. Attempts to use antibody-mediated depletion to discern the specific role of neutrophils in infection control and pathologyin vivorevealed that although Ly6Ghighneutrophils were eliminated from the blood and oviducts with this treatment, immature neutrophils and high levels of tissue-damaging molecules were still detectable in the upper genital tract. These data support the role of neutrophils in chlamydia-induced pathology and reveal that novel methods of depletion must be developed before their role can be specifically determinedin vivo.

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