scholarly journals A Time Course for Susceptibility to Staphylococcus aureus Respiratory Infection during Influenza in a Swine Model

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
Elizabeth A. Smith ◽  
Sandeep R. P. Kumar ◽  
Jagadeeswaran Deventhiran ◽  
Thomas E. Cecere ◽  
Tanya LeRoith ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Influenza A ◽  
Time Course ◽  
Treatment Options ◽  
Flow Cytometric Analysis ◽  
Respiratory Physiology ◽  
Swine Model ◽  
Lung Pathology ◽  
Nursery Pigs ◽  
Recent Emergence

Bacterial superinfections following influenza A virus (IAV) are predominant causes of morbidity in humans. The recent emergence of methicillin-resistant Staphylococcus aureus (MRSA) and highly virulent IAV strains has reduced treatment options. Development of an appropriate animal model to study secondary S. aureus infections may provide important information regarding disease pathogenesis. Pigs are natural hosts to both IAV and S. aureus and have respiratory physiology and immune response comparable to humans. To establish a time course of susceptibility to S. aureus after IAV infection, nursery pigs infected intranasally with IAV were challenged with MRSA at different time points. Lung pathology scores and MRSA CFU were evaluated in dual-infected animals after IAV infection. Flow cytometric analysis of bronchoalveolar lavage fluid indicated differences between treatments. These results demonstrate the appropriateness of an intranasal challenge model in nursery pigs for studying the pathogenesis of IAV and S. aureus coinfection and provide insights into the timeframe for susceptibility of IAV-infected pigs to secondary S. aureus infection.

scholarly journals The Antimicrobial Activity of the AGXX® Surface Coating Requires a Small Particle Size to Efficiently Kill Staphylococcus aureus

2021 ◽  
Vol 12 ◽  
Author(s):  
Nico Linzner ◽  
Haike Antelmann
Keyword(s):  
Staphylococcus Aureus ◽  
Antimicrobial Activity ◽  
Particle Size ◽  
Surface Coating ◽  
Time Course ◽  
Treatment Options ◽  
Volume Ratio ◽  
The Novel ◽  
Major Health ◽  
Time Period

Methicillin-resistant Staphylococcus aureus (MRSA) isolates are often resistant to multiple antibiotics and pose a major health burden due to limited treatment options. The novel AGXX® surface coating exerts strong antimicrobial activity and successfully kills multi-resistant pathogens, including MRSA. The mode of action of AGXX® particles involves the generation of reactive oxygen species (ROS), which induce an oxidative and metal stress response, increased protein thiol-oxidations, protein aggregations, and an oxidized bacillithiol (BSH) redox state in S. aureus. In this work, we report that the AGXX® particle size determines the effective dose and time-course of S. aureus USA300JE2 killing. We found that the two charges AGXX®373 and AGXX®383 differ strongly in their effective concentrations and times required for microbial killing. While 20–40 μg/ml AGXX®373 of the smaller particle size of 1.5–2.5 μm resulted in >99.9% killing after 2 h, much higher amounts of 60–80 μg/ml AGXX®383 of the larger particle size of >3.2 μm led to a >99% killing of S. aureus USA300JE2 within 3 h. Smaller AGXX® particles have a higher surface/volume ratio and therefore higher antimicrobial activity to kill at lower concentrations in a shorter time period compared to the larger particles. Thus, in future preparations of AGXX® particles, the size of the particles should be kept at a minimum for maximal antimicrobial activity.

scholarly journals Rhodomyrtone Accumulates in Bacterial Cell Wall and Cell Membrane and Inhibits the Synthesis of Multiple Cellular Macromolecules in Epidemic Methicillin-Resistant Staphylococcus aureus

Antibiotics ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 543
Author(s):  
Ozioma F. Nwabor ◽  
Sukanlaya Leejae ◽  
Supayang P. Voravuthikunchai
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Wall ◽  
Cell Membrane ◽  
Bacterial Cell ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Treatment Options ◽  
Bacterial Cell Wall ◽  
Methicillin Resistant ◽  
Gram Positive Bacteria ◽  
Inhibitor Compounds

As the burden of antibacterial resistance worsens and treatment options become narrower, rhodomyrtone—a novel natural antibiotic agent with a new antibacterial mechanism—could replace existing antibiotics for the treatment of infections caused by multi-drug resistant Gram-positive bacteria. In this study, rhodomyrtone was detected within the cell by means of an easy an inexpensive method. The antibacterial effects of rhodomyrtone were investigated on epidemic methicillin-resistant Staphylococcus aureus. Thin-layer chromatography demonstrated the entrapment and accumulation of rhodomyrtone within the bacterial cell wall and cell membrane. The incorporation of radiolabelled precursors revealed that rhodomyrtone inhibited the synthesis of macromolecules including DNA, RNA, proteins, the cell wall, and lipids. Following the treatment with rhodomyrtone at MIC (0.5–1 µg/mL), the synthesis of all macromolecules was significantly inhibited (p ≤ 0.05) after 4 h. Inhibition of macromolecule synthesis was demonstrated after 30 min at a higher concentration of rhodomyrtone (4× MIC), comparable to standard inhibitor compounds. In contrast, rhodomyrtone did not affect lipase activity in staphylococci—both epidemic methicillin-resistant S. aureus and S. aureus ATCC 29213. Interfering with the synthesis of multiple macromolecules is thought to be one of the antibacterial mechanisms of rhodomyrtone.

scholarly journals Quantitative analysis of the CD8 + T–cell response to readily eliminated and persistent viruses

2000 ◽  
Vol 355 (1400) ◽  
pp. 1093-1101 ◽  
Author(s):  
P. C. Doherty ◽  
J. M. Riberdy ◽  
G. T. Belz
Keyword(s):  
T Cells ◽  
T Cell ◽  
Influenza A ◽  
Flow Cytometric Analysis ◽  
T Cell Response ◽  
Basic Question ◽  
Cell Mediated Immunity ◽  
Specific Response ◽  
Turnover Rates

The recent development of techniques for the direct staining of peptide–specific CD8 + T cells has revolutionized the analysis of cell–mediated immunity (CMI) in virus infections. This approach has been used to quantify the acute and long–term consequences of infecting laboratory mice with the readily eliminated influenza A viruses (fluA) and a persistent γherpesvirus (γHV). It is now, for the first time, possible to work with real numbers in the analysis of CD8 + T CMI, and to define various characteristics of the responding lymphocytes both by direct flow cytometric analysis and by sorting for further in vitro manipulation. Relatively little has yet been done from the latter aspect, though we are rapidly accumulating a mass of numerical data. The acute, antigen–driven phases of the fluA and γHV–specific response look rather similar, but CD8 + T–cell numbers are maintained in the long term at a higher ‘set point’ in the persistent infection. Similarly, these ‘memory’ T cells continue to divide at a much greater rate in the γHV–infected mice. New insights have also been generated on the nature of the recall response following secondary challenge in both experimental systems, and the extent of protection conferred by large numbers of virus–specific CD8 + T cells has been determined. However, there are still many parameters that have received little attention, partly because they are difficult to measure. These include the rate of antigen–specific CD8 + T–cell loss, the extent of the lymphocyte ‘diaspora’ to other tissues, and the diversity of functional characteristics, turnover rates, clonal life spans and recirculation profiles. The basic question for immunologists remains how we reconcile the extraordinary plasticity of the immune system with the mechanisms that maintain a stable milieu interieur. This new capacity to quantify CD8 + T–cell responses in readily manipulated mouse models has obvious potential for illuminating homeostatic control, particularly if the experimental approaches to the problem are designed in the context of appropriate predictive models.

scholarly journals Exacerbation of Influenza Virus Infections in Mice by Intranasal Treatments and Implications for Evaluation of Antiviral Drugs

2012 ◽  
Vol 56 (12) ◽  
pp. 6328-6333 ◽  
Author(s):  
Donald F. Smee ◽  
Mark von Itzstein ◽  
Beenu Bhatt ◽  
E. Bart Tarbet
Keyword(s):  
Influenza Virus ◽  
Influenza A ◽  
H1n1 Virus ◽  
Antiviral Agent ◽  
Virus Production ◽  
Lung Pathology ◽  
Virus Infections ◽  
Challenge Dose ◽  
Virus Challenge ◽  
Time To Death

ABSTRACTCompounds lacking oral activity may be delivered intranasally to treat influenza virus infections in mice. However, intranasal treatments greatly enhance the virulence of such virus infections. This can be partially compensated for by giving reduced virus challenge doses. These can be 100- to 1,000-fold lower than infections without such treatment and still cause equivalent mortality. We found that intranasal liquid treatments facilitate virus production (probably through enhanced virus spread) and that lung pneumonia was delayed by only 2 days relative to a 1,000-fold higher virus challenge dose not accompanied by intranasal treatments. In one study, zanamivir was 90 to 100% effective at 10 mg/kg/day by oral, intraperitoneal, and intramuscular routes against influenza A/California/04/2009 (H1N1) virus in mice. However, the same compound administered intranasally at 20 mg/kg/day for 5 days gave no protection from death although the time to death was significantly delayed. A related compound, Neu5Ac2en (N-acetyl-2,3-dehydro-2-deoxyneuraminic acid), was ineffective at 100 mg/kg/day. Intranasal zanamivir and Neu5Ac2en were 70 to 100% protective against influenza A/NWS/33 (H1N1) virus infections at 0.1 to 10 and 30 to 100 mg/kg/day, respectively. Somewhat more difficult to treat was A/Victoria/3/75 virus that required 10 mg/kg/day of zanamivir to achieve full protection. These results illustrate that treatment of influenza virus infections by the intranasal route requires consideration of both virus challenge dose and virus strain in order to avoid compromising the effectiveness of a potentially useful antiviral agent. In addition, the intranasal treatments were shown to facilitate virus replication and promote lung pathology.

scholarly journals Protection of Mice and Poultry from Lethal H5N1 Avian Influenza Virus through Adenovirus-Based Immunization

2006 ◽  
Vol 80 (4) ◽  
pp. 1959-1964 ◽  
Author(s):  
Wentao Gao ◽  
Adam C. Soloff ◽  
Xiuhua Lu ◽  
Angela Montecalvo ◽  
Doan C. Nguyen ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Avian Influenza ◽  
Avian Influenza Virus ◽  
Influenza A ◽  
Recombinant Adenovirus ◽  
Critical Role ◽  
H5n1 Avian Influenza Virus ◽  
Recent Emergence ◽  
Boost Vaccine ◽  
Subcutaneous Immunization

ABSTRACT The recent emergence of highly pathogenic avian influenza virus (HPAI) strains in poultry and their subsequent transmission to humans in Southeast Asia have raised concerns about the potential pandemic spread of lethal disease. In this paper we describe the development and testing of an adenovirus-based influenza A virus vaccine directed against the hemagglutinin (HA) protein of the A/Vietnam/1203/2004 (H5N1) (VN/1203/04) strain isolated during the lethal human outbreak in Vietnam from 2003 to 2005. We expressed different portions of HA from a recombinant replication-incompetent adenoviral vector, achieving vaccine production within 36 days of acquiring the virus sequence. BALB/c mice were immunized with a prime-boost vaccine and exposed to a lethal intranasal dose of VN/1203/04 H5N1 virus 70 days later. Vaccination induced both HA-specific antibodies and cellular immunity likely to provide heterotypic immunity. Mice vaccinated with full-length HA were fully protected from challenge with VN/1203/04. We next evaluated the efficacy of adenovirus-based vaccination in domestic chickens, given the critical role of fowl species in the spread of HPAI worldwide. A single subcutaneous immunization completely protected chickens from an intranasal challenge 21 days later with VN/1203/04, which proved lethal to all control-vaccinated chickens within 2 days. These data indicate that the rapid production and subsequent administration of recombinant adenovirus-based vaccines to both birds and high-risk individuals in the face of an outbreak may serve to control the pandemic spread of lethal avian influenza.

scholarly journals Methicillin-resistant Staphylococcus aureus of the clonal lineage ST5-SCCmecII-t2460 was associated with high mortality in a Wuhan hospital

2021 ◽  
Author(s):  
Xuehan Li ◽  
Jing Zhang ◽  
Yifan Zhang ◽  
Junying Zhou ◽  
Xinwei Li ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Antibiotic Resistance ◽  
White Blood Cells ◽  
Resistance Rate ◽  
Molecular Characteristics ◽  
Invasive Procedures ◽  
Methicillin Resistant ◽  
Small Colony Variant ◽  
Recent Emergence ◽  
Resistance Rates

AbstractMethicillin-resistant Staphylococcus aureus (MRSA) is an important human pathogen that can cause serious infectious diseases. An emerging MRSA strain, ST5-SCCmecII spa-type-t2460 (SMRSA), has spread rapidly since its recent emergence in China, but little information is available about this lineage. In this study, 91 MRSA isolates were collected from patients treated in the Zhongnan Hospital, Wuhan University, from 2018 to 2019, and investigated for their molecular characteristics, antibiotic resistance profiles, and clinical characteristics. The predominant lineage, SMRSA, accounted for 37.4% (34/91) of the isolates, followed by ST239-SCCmecIII-t030 (19.8%, 18/91) and ST59-SCCmecIV-t437 (8.8%, 8/91). In contrast to the latter two non-SMRSA (nSMRSA) lineages, which are among the main MRSA found in Chinese settings, SMRSA exhibited small colony variant (SCV) phenotype and had extremely high resistance rates to erythromycin (100.0%), clindamycin (100.0%), levofloxacin (100.0%), tetracycline (97.1%), moxifloxacin (97.1%), and ciprofloxacin (100%), but was more susceptible to rifampicin (resistance rate 3%). The levels of white blood cells (WBC) and procalcitonin (PCT) and the 30-day mortality in patients infected with SMRSA were (12.54 ± 6.61) × 109/L, 0.66 ng/mL, and 52.9%, respectively, which were much higher than those in patients infected with nSMRSA. In addition, patients infected with SMRSA were more frequently admitted to the intensive care unit (ICU) and submitted to invasive procedures than those infected with nSMRSA. In conclusion, SMRSA showed SCV phenotype and exhibited multiple antibiotic-resistance profiles. In this study, SMRSA was associated with serious infections and poor prognosis. Compared with ST239, ST59, or other nSMRSA strains, patients infected with SMRSA strains have higher 30-day mortality, increased levels of inflammatory biomarkers, and more frequent ICU hospitalization and invasive procedures.

scholarly journals Multiparameter Flow Cytometric Analysis of Antibiotic Effects on Membrane Potential, Membrane Permeability, and Bacterial Counts of Staphylococcus aureus andMicrococcus luteus

2000 ◽  
Vol 44 (4) ◽  
pp. 827-834 ◽  
Author(s):  
David J. Novo ◽  
Nancy G. Perlmutter ◽  
Richard H. Hunt ◽  
Howard M. Shapiro
Keyword(s):  
Staphylococcus Aureus ◽  
Flow Cytometry ◽  
Membrane Potential ◽  
Membrane Permeability ◽  
Micrococcus Luteus ◽  
Flow Cytometric Analysis ◽  
Bacterial Counts ◽  
Flow Cytometric ◽  
Permeability Parameter ◽  
Particle Counts

ABSTRACT Although flow cytometry has been used to study antibiotic effects on bacterial membrane potential (MP) and membrane permeability, flow cytometric results are not always well correlated to changes in bacterial counts. Using new, precise techniques, we simultaneously measured MP, membrane permeability, and particle counts of antibiotic-treated and untreated Staphylococcus aureus andMicrococcus luteus cells. MP was calculated from the ratio of red and green fluorescence of diethyloxacarbocyanine [DiOC2(3)]. A normalized permeability parameter was calculated from the ratio of far red fluorescence of the nucleic acid dye TO-PRO-3 and green DiOC2(3) fluorescence. Bacterial counts were calculated by the addition of polystyrene beads to the sample at a known concentration. Amoxicillin increased permeability within 45 min. At concentrations of <1 μg/ml, some organisms showed increased permeability but normal MP; this population disappeared after 4 h, while bacterial counts increased. At amoxicillin concentrations above 1 μg/ml, MP decreased irreversibly and the particle counts did not increase. Tetracycline and erythromycin caused smaller, dose- and time-dependent decreases in MP. Tetracycline concentrations of <1 μg/ml did not change permeability, while a tetracycline concentration of 4 μg/ml permeabilized 50% of the bacteria; 4 μg of erythromycin per ml permeabilized 20% of the bacteria. Streptomycin decreased MP substantially, with no effect on permeability; chloramphenicol did not change either permeability or MP. Erythromycin pretreatment of bacteria prevented streptomycin and amoxicillin effects. Flow cytometry provides a sensitive means of monitoring the dynamic cellular events that occur in bacteria exposed to antibacterial agents; however, it is probably simplistic to expect that changes in a single cellular parameter will suffice to determine the sensitivities of all species to all drugs.

scholarly journals GP96 drives exacerbation of secondary bacterial pneumonia following influenza A virus infection

2020 ◽  
Author(s):  
Tomoko Sumitomo ◽  
Masanobu Nakata ◽  
Satoshi Nagase ◽  
Yuki Takahara ◽  
Mariko Honda-Ogawa ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Influenza A Virus ◽  
Transcriptional Repression ◽  
Bacterial Pneumonia ◽  
Influenza A ◽  
Surface Expression ◽  
Lung Pathology ◽  
Direct Binding ◽  
Novel Therapeutic Strategies ◽  
Secondary Bacterial Pneumonia

AbstractInfluenza A virus (IAV) infection predisposes the host to secondary bacterial pneumonia, known as a major cause of morbidity and mortality during influenza epidemics. Analysis of interactions between IAV-infected human epithelial cells and Streptococcus pneumoniae revealed that infected cells ectopically exhibited the endoplasmic reticulum chaperon GP96 on the surface. Importantly, efficient pneumococcal adherence to epithelial cells was imparted by interactions with extracellular GP96 and integrin αV, with the surface expression mediated by GP96 chaperone activity. Furthermore, abrogation of adherence was gained by chemical inhibition or genetic knockout of GP96, as well as addition of RGD peptide. Direct binding of extracellular GP96 and pneumococci was shown to be mediated by pneumococcal oligopeptide permease components. Additionally, IAV infection induced activation of calpains and Snail1, which are responsible for degradation and transcriptional repression of junctional proteins in the host, respectively, indicating increased bacterial translocation across the epithelial barrier. Notably, treatment of IAV-infected mice with the GP96 inhibitor enhanced pneumococcal clearance from lung tissues and ameliorated lung pathology. Taken together, the present findings indicate a viral-bacterial synergy in relation to disease progression and suggest a paradigm for developing novel therapeutic strategies tailored to inhibit pneumococcal colonization in an IAV-infected respiratory tract.

Characterization of Staphylococcus aureus-Platelet Binding by Quantitative Flow Cytometric Analysis

1992 ◽  
Vol 166 (1) ◽  
pp. 65-73 ◽  
Author(s):  
M. R. Yeaman ◽  
P. M. Sullam ◽  
P. F. Dazin ◽  
D. C. Norman ◽  
A. S. Bayer
Keyword(s):  
Staphylococcus Aureus ◽  
Flow Cytometric Analysis ◽  
Flow Cytometric ◽  
Platelet Binding ◽  
Quantitative Flow

scholarly journals Obatoclax, Saliphenylhalamide, and Gemcitabine Inhibit Influenza A Virus Infection

2012 ◽  
Vol 287 (42) ◽  
pp. 35324-35332 ◽  
Author(s):  
Oxana V. Denisova ◽  
Laura Kakkola ◽  
Lin Feng ◽  
Jakob Stenman ◽  
Ashwini Nagaraj ◽  
...  
Keyword(s):  
Influenza A ◽  
Treatment Options ◽  
Antiviral Agents ◽  
Cell Type ◽  
Influenza A Viruses ◽  
Novel Host ◽  
Chemical Screen ◽  
Species Specific ◽  
Host Target ◽  
Transcription And Replication

Influenza A viruses (IAVs) infect humans and cause significant morbidity and mortality. Different treatment options have been developed; however, these were insufficient during recent IAV outbreaks. Here, we conducted a targeted chemical screen in human nonmalignant cells to validate known and search for novel host-directed antivirals. The screen validated saliphenylhalamide (SaliPhe) and identified two novel anti-IAV agents, obatoclax and gemcitabine. Further experiments demonstrated that Mcl-1 (target of obatoclax) provides a novel host target for IAV treatment. Moreover, we showed that obatoclax and SaliPhe inhibited IAV uptake and gemcitabine suppressed viral RNA transcription and replication. These compounds possess broad spectrum antiviral activity, although their antiviral efficacies were virus-, cell type-, and species-specific. Altogether, our results suggest that phase II obatoclax, investigational SaliPhe, and FDA/EMEA-approved gemcitabine represent potent antiviral agents.

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