Denise Toney - Academia.edu (original) (raw)

Papers by Denise Toney

Research paper thumbnail of Alterations in protein expression and complement resistance of pathogenic Naegleria amoebae

Infection and Immunity, 1992

Highly pathogenic strains of Naegleria fowleri activate the alternative complement pathway but ar... more Highly pathogenic strains of Naegleria fowleri activate the alternative complement pathway but are resistant to lysis. In contrast, weakly pathogenic and nonpathogenic Naegleria spp. activate the complement pathway and are readily lysed. The present study was undertaken to determine whether surface components on amoebae accounted for resistance to complement lysis. Enzymatic removal of surface components from highly pathogenic N. fowleri with phosphatidylinositol-specific phospholipase C or with endoglycosidase H increased the susceptibility of these amoebae to complement-mediated lysis. Similar treatment of nonpathogenic amoebae had no effect on susceptibility to complement. Tunicamycin treatment of highly and weakly pathogenic N. fowleri increased susceptibility to lysis by complement in a dose-related manner. Tunicamycin treatment did not alter the susceptibility of nonpathogenic amoebae to complement. Proteins of 234 and 47 kDa were detected in supernatant fluid from phosphatidy...

Research paper thumbnail of Influenza Antiviral Prescribing Practices and the Influence of Rapid Testing Among Primary Care Providers in the US, 2009–2016

Open Forum Infectious Diseases, 2019

Background Early influenza antiviral treatment within 2 days of illness onset can reduce illness ... more Background Early influenza antiviral treatment within 2 days of illness onset can reduce illness severity and duration. Reliance on low sensitivity rapid influenza diagnostic tests (RIDTs) to guide antiviral prescribing has been reported. We describe antiviral prescribing practices among primary care providers from a large surveillance network in the United States. Methods From 2009–2016, a network of 36 to 68 outpatient clinics per year collected respiratory specimens and clinical data for patients with influenza-like illness (ILI). Specimens were tested for influenza using polymerase chain reaction (PCR). We used multivariable logistic regression to assess factors influencing antiviral prescribing. Results Among 13 540 patients with ILI, 2766 (20%) were prescribed antivirals. In age groups recommended to receive empiric antiviral treatment for suspected influenza, 11% of children <2 years and 23% of adults ≥65 years received a prescription. Among 3681 patients with a positive P...

Research paper thumbnail of Simultaneous Outbreaks of Extensively Drug Resistant Acinetobacter baumannii and Carbapenemase Producing Enterobacteriaceae in an Intensive Care Unit: Interruption of Epidemic but not Endemic Transmission

Background: Carbapenemase-producing Enterobacteriaceae (CPE) and multidrug-resistant Acinetobacte... more Background: Carbapenemase-producing Enterobacteriaceae (CPE) and multidrug-resistant Acinetobacter baumannii (AB) have emerged as vexing problems in infection control. Our objective was to describe concurrent outbreaks of CPE and extensively drug resistant (XDR) AB in an intensive care unit (ICU) and interventions to control their spread. Methods: We investigated concurrent clusters of CPE and XDR AB in a surgical ICU that occurred 1/10-3/10. Polymerase chain reaction was used to detect the presence of blaKPC and resistance plasmids in carbapenemase phenotype-positive Enterobacteriaceae. Pulsed-field gel electrophoresis was performed to assess clonality of XDR AB (defined as resistance to all FDA approved antibiotics, including colistin and tigecycline). Enhanced infection control measures (staff education, room/personnel cohorting, and enhanced environmental cleaning with validation using ATP testing) were implemented 1/28/10. Efficacy of the interventions was evaluated by interrup...

Research paper thumbnail of Viral Gastroenteritis: Pathogenesis and Laboratory Detection and Characterization in the Commonwealth of Virginia

Clinical Microbiology Newsletter, 2011

Public health laboratories perform testing to identify and characterize cases and clusters of acu... more Public health laboratories perform testing to identify and characterize cases and clusters of acute gastroenteritis (AGE). Viral pathogens, in particular norovirus, are reportedly the most common cause of AGE outbreaks. CaliciNet, a centralized database at the Centers for Disease Control and Prevention, collects and compares viral sequences for surveillance and outbreak tracking purposes. At the state level, viral agent testing supports epidemiologic investigations of AGE outbreaks. The resulting data are used to educate the public health and medical communities and to track mutations that may impact testing methods. A retrospective analysis of norovirus data generated by the Virginia State Laboratory between 2001 and 2009 assessed statewide trends compared to national data. The data demonstrate that Norovirus genogroup II outbreaks are the most prevalent cause of AGE outbreaks and that outbreaks exhibit a higher occurrence in the winter months and in adult care facilities in Virginia and nationally.

Research paper thumbnail of Control of Simultaneous Outbreaks of Carbapenemase-Producing Enterobacteriaceae and Extensively Drug-ResistantAcinetobacter baumanniiInfection in an Intensive Care Unit Using Interventions Promoted in the Centers for Disease Control and Prevention 2012 Carbapenemase-Resistant Enterobacteriaceae T...

Infection Control & Hospital Epidemiology, 2014

ObjectiveWe describe the efficacy of enhanced infection control measures, including those recomme... more ObjectiveWe describe the efficacy of enhanced infection control measures, including those recommended in the Centers for Disease Control and Prevention’s 2012 carbapenem-resistant Enterobacteriaceae (CRE) toolkit, to control concurrent outbreaks of carbapenemase-producing Enterobacteriaceae (CPE) and extensively drug-resistantAcinetobacter baumannii(XDR-AB).DesignBefore-after intervention study.SettingFifteen-bed surgical trauma intensive care unit (ICU).MethodsWe investigated the impact of enhanced infection control measures in response to clusters of CPE and XDR-AB infections in an ICU from April 2009 to March 2010. Polymerase chain reaction was used to detect the presence ofblaKPCand resistance plasmids in CRE. Pulsed-field gel electrophoresis was performed to assess XDR-AB clonality. Enhanced infection-control measures were implemented in response to ongoing transmission of CPE and a new outbreak of XDR-AB. Efficacy was evaluated by comparing the incidence rate (IR) of CPE and X...

Research paper thumbnail of Molecular genotyping and quantitation assay for rotavirus surveillance

Journal of virological methods, Jan 17, 2014

Rotavirus genotyping is useful for surveillance purposes especially in areas where rotavirus vacc... more Rotavirus genotyping is useful for surveillance purposes especially in areas where rotavirus vaccination has been or will be implemented. RT-PCR based molecular methods have been applied widely, but quantitative assays targeting a broad spectrum of genotypes have not been developed. Three real time RT-PCR panels were designed to identify G1, G2, G9, G12 (panel GI), G3, G4, G8, G10 (panel GII), and P[4], P[6], P[8], P[10], P[11] (panel P), respectively. An assay targeting NSP3 was included in both G panels as an internal control. The cognate assays were also formulated as one RT-PCR-Luminex panel for simultaneous detection of all the genotypes listed above plus P[9]. The assays were evaluated with various rotavirus isolates and 89 clinical samples from Virginia, Bangladesh and Tanzania, and exhibited 95% (81/85) sensitivity compared with the conventional RT-PCR-Gel-electrophoresis method, and 100% concordance with sequencing. Real time assays identified a significantly higher rate of...

Research paper thumbnail of Modulation of Biological Functions of Naegleria fowleri Amoebae by Growth Medium

The Journal of Eukaryotic Microbiology, 1994

inhibits cyclization of an excised intervening sequence RNA is a cleavage-li-petitive inhibition ... more inhibits cyclization of an excised intervening sequence RNA is a cleavage-li-petitive inhibition of Group I intron RNA self-splicing by aminoglycoside antibiotics.

Research paper thumbnail of Modulation of Complement Resistance and Virulence of Naegleria fowleri Amoebae by Alterations in Growth Media

The Journal of Eukaryotic Microbiology, 1994

velopment of Eimeria callospermophili and E. billamelata from the Uinta ground-squirrel Spermophi... more velopment of Eimeria callospermophili and E. billamelata from the Uinta ground-squirrel Spermophilus armatus in cultured cells.

Research paper thumbnail of The Interaction of Acanthamoeba spp. with Activated Macrophages and with Macrophage Cell Lines

The Journal of Eukaryotic Microbiology, 1998

Acanthamoeba spp. are free-living amebae associated with amebic keratitis and chronic granulomato... more Acanthamoeba spp. are free-living amebae associated with amebic keratitis and chronic granulomatous amebic encephalitis. Thc present studies were undertaken to compare the pathogenicity of three species of Acanthamoeba in B,C,F, mice after intranasal challenge with Acanrhamoeba-induced cytopathogenicity for different macrophage populations. The ability of murine macrophage cell lines and activated murine peritoneal macrophages to lyse Acantkatnoeba has been assessed by coincubating macrophages with 3Huridine labeled amebae. Conversely, destruction of macrophages by Acatitharnoeba was determined by measuring the release of chromium-5 1 from radiolabeled macrophages. Acanthanwebn culbertsoni, which is highly pathogenic for mice, destroys macrophage cultures in vitro. Activated primary peritoneal macrophages were more resistant to Acutrrhamoeba-mediated destruction than macrophage cell lines activated in vitro. Activated macrophages were capable of limited destruction of Acanthamoeba polyphaga and Acanfhnmoeba castrllanii. Acanfhanioeba-specific antibodies increased the amebicidal activity of activated macrophages. Macrophage-mediated destruction was by contact-dependent cytolysis and by ingestion of amebae. Conditioned medium obtained from macrophage cultures after treatment with lipopolysaccharide and interferon gamma was neither cytolytic nor cytostatic for Acanthamoeba spp. Purified recombinant cytokines including tumor necrosis factor a. interleukin la. and interleukin 10, alone or in combination, were not cytolytic for Acanrhamoeba trophozoites.

Research paper thumbnail of Amebicidal activity of plant extracts from Southeast Asia on Acanthamoeba spp

Parasitology Research, 1998

The effect of 100 polar and 100 nonpolar plant extract materials obtained from Southeast Asia wer... more The effect of 100 polar and 100 nonpolar plant extract materials obtained from Southeast Asia were evaluated for amebicidal activity in vitro against three species of Acanthamoeba. A. culbertsoni, A. castellanii, and A. polyphaga, the causative agents of granulomatous amebic encephalitis and amebic keratitis, were studied in vitro to determine whether the plant extracts exhibited amebicidal activity or induced encystment of the amebae. Of the 200 plant extracts tested, extracts obtained from three plants (Ipomoea sp., Kaempferia galanga, and Cananga odorata) were amebicidal for all three species of Acanthamoeba and a fourth extract prepared from Gastrochilus panduratum was lytic for A. polyphaga and growth-inhibitory for A. castellanii and A. culbertsoni. Three plant extracts induced encystment of all three species of Acanthamoeba. Select plant extracts were tested as well for tumoricidal activity against B103 neuroblastoma cells. Some plant extracts that exhibited tumoricidal activity for B103 cells were not amebicidal for Acanthamoeba spp. Additionally, the polar and nonpolar extracts that exhibited amebicidal activity were also tested for activity against primary murine peritoneal macrophage cultures. Plant extracts that demonstrated tumoricidal or amebicidal activity were not lytic for normal macrophage cultures.

Research paper thumbnail of Dependence of Growth, Metabolic Expression, and Pathogenicity of Naegleria fowleri on Exogenous Porphyrins

The Journal of Parasitology, 1996

The pathogenicity of the free-living amoeba Naegleria fowleri is modulated by the composition of ... more The pathogenicity of the free-living amoeba Naegleria fowleri is modulated by the composition of the medium used for cultivation. The constituents that determine the level of pathogenicity of N. fowleri, however, have not been definitively established. The present study examined the effects of selected porphyrins on N. fowleri amoebae. The iron-containing porphyrins, hemin or hematin, or the iron-free porphyrin, protoporphyrin IX, were effective in supporting growth of N. fowleri in Cline medium lacking serum. Iron-binding proteins, including hemoglobin, could not satisfy the growth requirement of the amoebae for exogenous porphyrin. Expression of biological functions including azocaseinase activity, agglutination, mobility, complement susceptibility, and virulence were altered by the composition of the growth medium. Amoebae grown in Cline medium supplemented with either hemin or protoporphyrin IX displayed greater mobility and were more resistant to lysis by complement than those grown in Nelson medium. Similarly, amoebae grown in Cline medium supplemented with either hemin or protoporphyrin IX were more pathogenic for B6C3F1 mice than those grown in Nelson medium. The addition of protoporphyrin IX to Nelson medium resulted in a modest increase in mobility, resistance to complement lysis and virulence when compared to N. fowleri amoebae grown in Nelson medium without added porphyrin.

Research paper thumbnail of Multiplex reverse transcription PCR Luminex assay for detection and quantitation of viral agents of gastroenteritis

Journal of Clinical Virology, 2011

Background-Several viruses can cause diarrheal disease, a leading cause of morbidity and mortalit... more Background-Several viruses can cause diarrheal disease, a leading cause of morbidity and mortality worldwide. Existing diagnostic methods include ELISA and nucleic acid amplification, usually performed individually. Objectives-(1) Develop a multiplexed assay for simultaneous detection of major enteric viral pathogens. (2) Quantitation of viral load by normalizing with an extrinsic control. Study Design-A simple protocol combining a one-step multiplex reverse transcriptionpolymerase chain reaction (RT-PCR) with microsphere-based fluorescence detection was developed for norovirus GI and GII, rotavirus, astrovirus, sapovirus, and adenovirus. An extrinsic control, bacteriophage MS2, was spiked into each fecal sample before nucleic acid extraction to normalize between samples for the efficiency of nucleic acid extraction and amplification.

Research paper thumbnail of Evaluating Gulls as Potential Vehicles of Salmonella enterica Serotype Newport (JJPX01.0061) Contamination of Tomatoes Grown on the Eastern Shore of Virginia

Applied and Environmental Microbiology, 2013

Salmonella enterica serovar Newport pattern JJPX01.0061 has been identified as causing several mu... more Salmonella enterica serovar Newport pattern JJPX01.0061 has been identified as causing several multistate outbreaks in the last 10 years, primarily due to contamination of tomatoes grown in Virginia. The goal of this study was to evaluate gulls as a potential vehicle of S . Newport pattern 61 contamination for tomatoes grown on the Eastern Shore of Virginia. Gull fecal samples were collected at four sites in eastern Virginia for 3 months (May to July) in 2012, resulting in 360 samples, among which Salmonella was isolated from 62 samples. Twenty-two serotypes and 26 pulsed-field gel electrophoresis DNA fingerprint patterns, including S . Newport pattern 61, were identified. All of the patterns that were isolated multiple times, with the exception of S . Newport patterns JJPX01.0030 and JJPX01.0061, were clustered in time and geographical location. These results strongly suggest that both patterns of S . Newport are endemic to sites on the Eastern Shore where gulls were sampled. This ...

Research paper thumbnail of Comparison of MALDI-TOF/MS and LC-QTOF/MS methods for the identification of enteric bacteria

International Journal of Mass Spectrometry, 2010

Two complementary mass spectrometric techniques were evaluated for their applicability as methods... more Two complementary mass spectrometric techniques were evaluated for their applicability as methods for foodborne pathogen characterization, biomarker candidate discovery and identification. Ten clinical isolates of closely related organisms, Escherichia coli, Shigella sonnei and Shigella flexneri, were chosen for this study. Whole cell lysates were analyzed using both matrix assisted laser desorption-ionization timeof-flight mass spectrometry (MALDI-TOF/MS) and liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF/MS). Evaluation of isolate mass spectra revealed unique protein profile patterns and potential biomarkers capable of species and sub-species identification. Strengths of each MS method, in addition to their advantages over traditional methods, are highlighted and a brief discussion of their potential as standard tools in the laboratory is presented.

Research paper thumbnail of Alterations in protein expression and complement resistance of pathogenic Naegleria amoebae

Infection and Immunity, 1992

Highly pathogenic strains of Naegleria fowleri activate the alternative complement pathway but ar... more Highly pathogenic strains of Naegleria fowleri activate the alternative complement pathway but are resistant to lysis. In contrast, weakly pathogenic and nonpathogenic Naegleria spp. activate the complement pathway and are readily lysed. The present study was undertaken to determine whether surface components on amoebae accounted for resistance to complement lysis. Enzymatic removal of surface components from highly pathogenic N. fowleri with phosphatidylinositol-specific phospholipase C or with endoglycosidase H increased the susceptibility of these amoebae to complement-mediated lysis. Similar treatment of nonpathogenic amoebae had no effect on susceptibility to complement. Tunicamycin treatment of highly and weakly pathogenic N. fowleri increased susceptibility to lysis by complement in a dose-related manner. Tunicamycin treatment did not alter the susceptibility of nonpathogenic amoebae to complement. Proteins of 234 and 47 kDa were detected in supernatant fluid from phosphatidy...

Research paper thumbnail of Influenza Antiviral Prescribing Practices and the Influence of Rapid Testing Among Primary Care Providers in the US, 2009–2016

Open Forum Infectious Diseases, 2019

Background Early influenza antiviral treatment within 2 days of illness onset can reduce illness ... more Background Early influenza antiviral treatment within 2 days of illness onset can reduce illness severity and duration. Reliance on low sensitivity rapid influenza diagnostic tests (RIDTs) to guide antiviral prescribing has been reported. We describe antiviral prescribing practices among primary care providers from a large surveillance network in the United States. Methods From 2009–2016, a network of 36 to 68 outpatient clinics per year collected respiratory specimens and clinical data for patients with influenza-like illness (ILI). Specimens were tested for influenza using polymerase chain reaction (PCR). We used multivariable logistic regression to assess factors influencing antiviral prescribing. Results Among 13 540 patients with ILI, 2766 (20%) were prescribed antivirals. In age groups recommended to receive empiric antiviral treatment for suspected influenza, 11% of children <2 years and 23% of adults ≥65 years received a prescription. Among 3681 patients with a positive P...

Research paper thumbnail of Simultaneous Outbreaks of Extensively Drug Resistant Acinetobacter baumannii and Carbapenemase Producing Enterobacteriaceae in an Intensive Care Unit: Interruption of Epidemic but not Endemic Transmission

Background: Carbapenemase-producing Enterobacteriaceae (CPE) and multidrug-resistant Acinetobacte... more Background: Carbapenemase-producing Enterobacteriaceae (CPE) and multidrug-resistant Acinetobacter baumannii (AB) have emerged as vexing problems in infection control. Our objective was to describe concurrent outbreaks of CPE and extensively drug resistant (XDR) AB in an intensive care unit (ICU) and interventions to control their spread. Methods: We investigated concurrent clusters of CPE and XDR AB in a surgical ICU that occurred 1/10-3/10. Polymerase chain reaction was used to detect the presence of blaKPC and resistance plasmids in carbapenemase phenotype-positive Enterobacteriaceae. Pulsed-field gel electrophoresis was performed to assess clonality of XDR AB (defined as resistance to all FDA approved antibiotics, including colistin and tigecycline). Enhanced infection control measures (staff education, room/personnel cohorting, and enhanced environmental cleaning with validation using ATP testing) were implemented 1/28/10. Efficacy of the interventions was evaluated by interrup...

Research paper thumbnail of Viral Gastroenteritis: Pathogenesis and Laboratory Detection and Characterization in the Commonwealth of Virginia

Clinical Microbiology Newsletter, 2011

Public health laboratories perform testing to identify and characterize cases and clusters of acu... more Public health laboratories perform testing to identify and characterize cases and clusters of acute gastroenteritis (AGE). Viral pathogens, in particular norovirus, are reportedly the most common cause of AGE outbreaks. CaliciNet, a centralized database at the Centers for Disease Control and Prevention, collects and compares viral sequences for surveillance and outbreak tracking purposes. At the state level, viral agent testing supports epidemiologic investigations of AGE outbreaks. The resulting data are used to educate the public health and medical communities and to track mutations that may impact testing methods. A retrospective analysis of norovirus data generated by the Virginia State Laboratory between 2001 and 2009 assessed statewide trends compared to national data. The data demonstrate that Norovirus genogroup II outbreaks are the most prevalent cause of AGE outbreaks and that outbreaks exhibit a higher occurrence in the winter months and in adult care facilities in Virginia and nationally.

Research paper thumbnail of Control of Simultaneous Outbreaks of Carbapenemase-Producing Enterobacteriaceae and Extensively Drug-ResistantAcinetobacter baumanniiInfection in an Intensive Care Unit Using Interventions Promoted in the Centers for Disease Control and Prevention 2012 Carbapenemase-Resistant Enterobacteriaceae T...

Infection Control & Hospital Epidemiology, 2014

ObjectiveWe describe the efficacy of enhanced infection control measures, including those recomme... more ObjectiveWe describe the efficacy of enhanced infection control measures, including those recommended in the Centers for Disease Control and Prevention’s 2012 carbapenem-resistant Enterobacteriaceae (CRE) toolkit, to control concurrent outbreaks of carbapenemase-producing Enterobacteriaceae (CPE) and extensively drug-resistantAcinetobacter baumannii(XDR-AB).DesignBefore-after intervention study.SettingFifteen-bed surgical trauma intensive care unit (ICU).MethodsWe investigated the impact of enhanced infection control measures in response to clusters of CPE and XDR-AB infections in an ICU from April 2009 to March 2010. Polymerase chain reaction was used to detect the presence ofblaKPCand resistance plasmids in CRE. Pulsed-field gel electrophoresis was performed to assess XDR-AB clonality. Enhanced infection-control measures were implemented in response to ongoing transmission of CPE and a new outbreak of XDR-AB. Efficacy was evaluated by comparing the incidence rate (IR) of CPE and X...

Research paper thumbnail of Molecular genotyping and quantitation assay for rotavirus surveillance

Journal of virological methods, Jan 17, 2014

Rotavirus genotyping is useful for surveillance purposes especially in areas where rotavirus vacc... more Rotavirus genotyping is useful for surveillance purposes especially in areas where rotavirus vaccination has been or will be implemented. RT-PCR based molecular methods have been applied widely, but quantitative assays targeting a broad spectrum of genotypes have not been developed. Three real time RT-PCR panels were designed to identify G1, G2, G9, G12 (panel GI), G3, G4, G8, G10 (panel GII), and P[4], P[6], P[8], P[10], P[11] (panel P), respectively. An assay targeting NSP3 was included in both G panels as an internal control. The cognate assays were also formulated as one RT-PCR-Luminex panel for simultaneous detection of all the genotypes listed above plus P[9]. The assays were evaluated with various rotavirus isolates and 89 clinical samples from Virginia, Bangladesh and Tanzania, and exhibited 95% (81/85) sensitivity compared with the conventional RT-PCR-Gel-electrophoresis method, and 100% concordance with sequencing. Real time assays identified a significantly higher rate of...

Research paper thumbnail of Modulation of Biological Functions of Naegleria fowleri Amoebae by Growth Medium

The Journal of Eukaryotic Microbiology, 1994

inhibits cyclization of an excised intervening sequence RNA is a cleavage-li-petitive inhibition ... more inhibits cyclization of an excised intervening sequence RNA is a cleavage-li-petitive inhibition of Group I intron RNA self-splicing by aminoglycoside antibiotics.

Research paper thumbnail of Modulation of Complement Resistance and Virulence of Naegleria fowleri Amoebae by Alterations in Growth Media

The Journal of Eukaryotic Microbiology, 1994

velopment of Eimeria callospermophili and E. billamelata from the Uinta ground-squirrel Spermophi... more velopment of Eimeria callospermophili and E. billamelata from the Uinta ground-squirrel Spermophilus armatus in cultured cells.

Research paper thumbnail of The Interaction of Acanthamoeba spp. with Activated Macrophages and with Macrophage Cell Lines

The Journal of Eukaryotic Microbiology, 1998

Acanthamoeba spp. are free-living amebae associated with amebic keratitis and chronic granulomato... more Acanthamoeba spp. are free-living amebae associated with amebic keratitis and chronic granulomatous amebic encephalitis. Thc present studies were undertaken to compare the pathogenicity of three species of Acanthamoeba in B,C,F, mice after intranasal challenge with Acanrhamoeba-induced cytopathogenicity for different macrophage populations. The ability of murine macrophage cell lines and activated murine peritoneal macrophages to lyse Acantkatnoeba has been assessed by coincubating macrophages with 3Huridine labeled amebae. Conversely, destruction of macrophages by Acatitharnoeba was determined by measuring the release of chromium-5 1 from radiolabeled macrophages. Acanthanwebn culbertsoni, which is highly pathogenic for mice, destroys macrophage cultures in vitro. Activated primary peritoneal macrophages were more resistant to Acutrrhamoeba-mediated destruction than macrophage cell lines activated in vitro. Activated macrophages were capable of limited destruction of Acanthamoeba polyphaga and Acanfhnmoeba castrllanii. Acanfhanioeba-specific antibodies increased the amebicidal activity of activated macrophages. Macrophage-mediated destruction was by contact-dependent cytolysis and by ingestion of amebae. Conditioned medium obtained from macrophage cultures after treatment with lipopolysaccharide and interferon gamma was neither cytolytic nor cytostatic for Acanthamoeba spp. Purified recombinant cytokines including tumor necrosis factor a. interleukin la. and interleukin 10, alone or in combination, were not cytolytic for Acanrhamoeba trophozoites.

Research paper thumbnail of Amebicidal activity of plant extracts from Southeast Asia on Acanthamoeba spp

Parasitology Research, 1998

The effect of 100 polar and 100 nonpolar plant extract materials obtained from Southeast Asia wer... more The effect of 100 polar and 100 nonpolar plant extract materials obtained from Southeast Asia were evaluated for amebicidal activity in vitro against three species of Acanthamoeba. A. culbertsoni, A. castellanii, and A. polyphaga, the causative agents of granulomatous amebic encephalitis and amebic keratitis, were studied in vitro to determine whether the plant extracts exhibited amebicidal activity or induced encystment of the amebae. Of the 200 plant extracts tested, extracts obtained from three plants (Ipomoea sp., Kaempferia galanga, and Cananga odorata) were amebicidal for all three species of Acanthamoeba and a fourth extract prepared from Gastrochilus panduratum was lytic for A. polyphaga and growth-inhibitory for A. castellanii and A. culbertsoni. Three plant extracts induced encystment of all three species of Acanthamoeba. Select plant extracts were tested as well for tumoricidal activity against B103 neuroblastoma cells. Some plant extracts that exhibited tumoricidal activity for B103 cells were not amebicidal for Acanthamoeba spp. Additionally, the polar and nonpolar extracts that exhibited amebicidal activity were also tested for activity against primary murine peritoneal macrophage cultures. Plant extracts that demonstrated tumoricidal or amebicidal activity were not lytic for normal macrophage cultures.

Research paper thumbnail of Dependence of Growth, Metabolic Expression, and Pathogenicity of Naegleria fowleri on Exogenous Porphyrins

The Journal of Parasitology, 1996

The pathogenicity of the free-living amoeba Naegleria fowleri is modulated by the composition of ... more The pathogenicity of the free-living amoeba Naegleria fowleri is modulated by the composition of the medium used for cultivation. The constituents that determine the level of pathogenicity of N. fowleri, however, have not been definitively established. The present study examined the effects of selected porphyrins on N. fowleri amoebae. The iron-containing porphyrins, hemin or hematin, or the iron-free porphyrin, protoporphyrin IX, were effective in supporting growth of N. fowleri in Cline medium lacking serum. Iron-binding proteins, including hemoglobin, could not satisfy the growth requirement of the amoebae for exogenous porphyrin. Expression of biological functions including azocaseinase activity, agglutination, mobility, complement susceptibility, and virulence were altered by the composition of the growth medium. Amoebae grown in Cline medium supplemented with either hemin or protoporphyrin IX displayed greater mobility and were more resistant to lysis by complement than those grown in Nelson medium. Similarly, amoebae grown in Cline medium supplemented with either hemin or protoporphyrin IX were more pathogenic for B6C3F1 mice than those grown in Nelson medium. The addition of protoporphyrin IX to Nelson medium resulted in a modest increase in mobility, resistance to complement lysis and virulence when compared to N. fowleri amoebae grown in Nelson medium without added porphyrin.

Research paper thumbnail of Multiplex reverse transcription PCR Luminex assay for detection and quantitation of viral agents of gastroenteritis

Journal of Clinical Virology, 2011

Background-Several viruses can cause diarrheal disease, a leading cause of morbidity and mortalit... more Background-Several viruses can cause diarrheal disease, a leading cause of morbidity and mortality worldwide. Existing diagnostic methods include ELISA and nucleic acid amplification, usually performed individually. Objectives-(1) Develop a multiplexed assay for simultaneous detection of major enteric viral pathogens. (2) Quantitation of viral load by normalizing with an extrinsic control. Study Design-A simple protocol combining a one-step multiplex reverse transcriptionpolymerase chain reaction (RT-PCR) with microsphere-based fluorescence detection was developed for norovirus GI and GII, rotavirus, astrovirus, sapovirus, and adenovirus. An extrinsic control, bacteriophage MS2, was spiked into each fecal sample before nucleic acid extraction to normalize between samples for the efficiency of nucleic acid extraction and amplification.

Research paper thumbnail of Evaluating Gulls as Potential Vehicles of Salmonella enterica Serotype Newport (JJPX01.0061) Contamination of Tomatoes Grown on the Eastern Shore of Virginia

Applied and Environmental Microbiology, 2013

Salmonella enterica serovar Newport pattern JJPX01.0061 has been identified as causing several mu... more Salmonella enterica serovar Newport pattern JJPX01.0061 has been identified as causing several multistate outbreaks in the last 10 years, primarily due to contamination of tomatoes grown in Virginia. The goal of this study was to evaluate gulls as a potential vehicle of S . Newport pattern 61 contamination for tomatoes grown on the Eastern Shore of Virginia. Gull fecal samples were collected at four sites in eastern Virginia for 3 months (May to July) in 2012, resulting in 360 samples, among which Salmonella was isolated from 62 samples. Twenty-two serotypes and 26 pulsed-field gel electrophoresis DNA fingerprint patterns, including S . Newport pattern 61, were identified. All of the patterns that were isolated multiple times, with the exception of S . Newport patterns JJPX01.0030 and JJPX01.0061, were clustered in time and geographical location. These results strongly suggest that both patterns of S . Newport are endemic to sites on the Eastern Shore where gulls were sampled. This ...

Research paper thumbnail of Comparison of MALDI-TOF/MS and LC-QTOF/MS methods for the identification of enteric bacteria

International Journal of Mass Spectrometry, 2010

Two complementary mass spectrometric techniques were evaluated for their applicability as methods... more Two complementary mass spectrometric techniques were evaluated for their applicability as methods for foodborne pathogen characterization, biomarker candidate discovery and identification. Ten clinical isolates of closely related organisms, Escherichia coli, Shigella sonnei and Shigella flexneri, were chosen for this study. Whole cell lysates were analyzed using both matrix assisted laser desorption-ionization timeof-flight mass spectrometry (MALDI-TOF/MS) and liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF/MS). Evaluation of isolate mass spectra revealed unique protein profile patterns and potential biomarkers capable of species and sub-species identification. Strengths of each MS method, in addition to their advantages over traditional methods, are highlighted and a brief discussion of their potential as standard tools in the laboratory is presented.