Infectious Diseases Research Laboratory

Tel Aviv, Israel

Infectious Diseases Research Laboratory

Tel Aviv, Israel
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News Article | May 17, 2017
Site: www.sciencedaily.com

The way in which heart and lung transplant recipients acquired a specific species of bacteria, Mycoplasma hominis, had been previously undefined, and the bacterium was difficult to test. Originally, this bacterium was considered to reside exclusively in, and be a potential pathogen of, the area of the reproductive and urinary organs -- the genitourinary tract. "This finding could affect how we approach the evaluation of organ donors," says Mark Wylam, M.D., who led the team of Mayo Clinic researchers on this study. "If potential transmission of these harmful bacteria can be identified and addressed, the recipient will face a decreased risk of infection and its serious complications. This study shows us that surveillance of both donor and recipient are important in recognizing M. hominis and the infection it can cause." Heart and lung transplant recipient infection caused by M. hominis may present with pleurisy (inflammation of membrane in chest cavity and lungs), surgical site infection and mediastinitis (inflammation of tissue in mid-chest). M. hominis resists most antibiotics, and the three antibiotic treatment recommendations for these infections are neither standard for post-transplant recipient care nor are they standard in therapy regimens for surgical site infections. The study, published recently in EBioMedicine, investigates Mayo Clinic lung and heart-lung transplants between 1998 and July 2015. Seven previously unreported cases of transplant recipients with M. hominis infection were discovered. In each case, pre-transplant sputum cultures had tested negative for M. hominis. Also, a literature review since 1950 found 15 cases of M. hominis infection in lung, heart or heart-lung transplant recipients. The way the germ spread remained uncertain. Given its normal residence in the genitourinary tract, some speculated that infection arose from urinary catheter placement during the transplant surgery. Mayo investigators noted two particular cases of M. hominis infection that each had received a single lung transplant from the same donor, and no other patients in the hospital were infected by M. hominis. The samples of the M. hominis taken from each infected individual were genetically indistinguishable, suggesting the infections had the same source. This finding, in addition to two other observations, supported the likelihood that M. hominis could be passed from transplant donor to recipient. Common testing methods have proven insufficient in identifying the bacteria, but the use of polymerase chain reaction detection developed by Robin Patel, M.D., director of Mayo Clinic's Infectious Diseases Research Laboratory, offers a more time-sensitive and specific test for the bacteria. With this method, researchers zoom in on a certain portion of DNA and then create multiple copies to amplify the segment. Polymerase chain reaction detection reduces the time to detect M. hominis to a few hours, compared to the two to five days needed for a culture media test. "The true rate of M. hominis infection may actually be higher than what we've seen reported," says Dr. Wylam. "Better detection methods like PCR tests have given us more insight into how common this bacterium is in the airway, which is especially important in heart or lung transplant recipients. More research is needed to learn about these bacteria when it's found far from its natural home in the genitourinary tract, and especially when it is transmitted to cardiothoracic transplant recipients."


News Article | May 16, 2017
Site: www.eurekalert.org

The way in which heart and lung transplant recipients acquired a specific species of bacteria, Mycoplasma hominis, had been previously undefined, and the bacterium was difficult to test. Originally, this bacterium was considered to reside exclusively in, and be a potential pathogen of, the area of the reproductive and urinary organs - the genitourinary tract. "This finding could affect how we approach the evaluation of organ donors," says Mark Wylam, M.D., who led the team of Mayo Clinic researchers on this study. "If potential transmission of these harmful bacteria can be identified and addressed, the recipient will face a decreased risk of infection and its serious complications. This study shows us that surveillance of both donor and recipient are important in recognizing M. hominis and the infection it can cause." Heart and lung transplant recipient infection caused by M. hominis may present with pleurisy (inflammation of membrane in chest cavity and lungs), surgical site infection and mediastinitis (inflammation of tissue in mid-chest). M. hominis resists most antibiotics, and the three antibiotic treatment recommendations for these infections are neither standard for post-transplant recipient care nor are they standard in therapy regimens for surgical site infections. The study, published recently in EBioMedicine, investigates Mayo Clinic lung and heart-lung transplants between 1998 and July 2015. Seven previously unreported cases of transplant recipients with M. hominis infection were discovered. In each case, pre-transplant sputum cultures had tested negative for M. hominis. Also, a literature review since 1950 found 15 cases of M. hominis infection in lung, heart or heart-lung transplant recipients. The way the germ spread remained uncertain. Given its normal residence in the genitourinary tract, some speculated that infection arose from urinary catheter placement during the transplant surgery. Mayo investigators noted two particular cases of M. hominis infection that each had received a single lung transplant from the same donor, and no other patients in the hospital were infected by M. hominis. The samples of the M. hominis taken from each infected individual were genetically indistinguishable, suggesting the infections had the same source. This finding, in addition to two other observations, supported the likelihood that M. hominis could be passed from transplant donor to recipient. Common testing methods have proven insufficient in identifying the bacteria, but the use of polymerase chain reaction detection developed by Robin Patel, M.D., director of Mayo Clinic's Infectious Diseases Research Laboratory, offers a more time-sensitive and specific test for the bacteria. With this method, researchers zoom in on a certain portion of DNA and then create multiple copies to amplify the segment. Polymerase chain reaction detection reduces the time to detect M. hominis to a few hours, compared to the two to five days needed for a culture media test. "The true rate of M. hominis infection may actually be higher than what we've seen reported," says Dr. Wylam. "Better detection methods like PCR tests have given us more insight into how common this bacterium is in the airway, which is especially important in heart or lung transplant recipients. More research is needed to learn about these bacteria when it's found far from its natural home in the genitourinary tract, and especially when it is transmitted to cardiothoracic transplant recipients." Mayo Clinic is a nonprofit organization committed to clinical practice, education and research, providing expert, whole-person care to everyone who needs healing. For more information, visit mayoclinic.org/about-mayo-clinic or newsnetwork.mayoclinic.org/.


McConeghy K.W.,University of Rhode Island | McConeghy K.W.,Infectious Diseases Research Laboratory | LaPlante K.L.,University of Rhode Island | LaPlante K.L.,Infectious Diseases Research Laboratory
Diagnostic Microbiology and Infectious Disease | Year: 2010

We investigated the activity of tigecycline in combination with gentamicin for the treatment of biofilm-forming methicillin-resistant and sensitive Staphylococcus aureus in an in vitro pharmacodynamic model. Tigecycline monotherapy demonstrated bacteriostatic activity throughout 48 h (-0.24 ± 0.17 log10 CFU/mL), whereas tigecycline in combination with gentamicin demonstrated significant (P < 0.002) kill (-3.66 ± 0.26 log10 CFU/mL) at 48 h. The addition of gentamicin to tigecycline significantly improved the killing activity of tigecycline in biofilm-forming S. aureus. © 2010 Elsevier Inc.


Gal-Mor O.,Infectious Diseases Research Laboratory | Gal-Mor O.,University of British Columbia | Elhadad D.,Infectious Diseases Research Laboratory | Elhadad D.,Tel Aviv University | And 4 more authors.
PLoS ONE | Year: 2011

To establish a successful infection within the host, a pathogen must closely regulate multiple virulence traits to ensure their accurate temporal and spatial expression. As a highly adapted intracellular pathogen, Salmonella enterica has acquired during its evolution various virulence genes via numerous lateral transfer events, including the acquisition of the Salmonella Pathogenicity Island 2 (SPI-2) and its associated effectors. Beneficial use of horizontally acquired genes requires that their expression is effectively coordinated with the already existing virulence programs and the regulatory set-up in the bacterium. As an example for such a mechanism, we show here that the ancestral PhoPQ system of Salmonella enterica is able to regulate directly the SPI-2 effector gene sseL (encoding a secreted deubiquitinase) in an SsrB-independent manner and that PhoP plays a part in a feed-forward regulatory loop, which fine-tunes the cellular level of SseL. Additionally, we demonstrate the presence of conserved cis regulatory elements in the promoter region of sseL and show direct binding of purified PhoP to this region. Interestingly, in contrast to the S. enterica PhoP, an ortholog regulator from a S. bongori SARC 12 strain was found to be impaired in promoting transcription of sseL and other genes from the PhoP regulon. These findings have led to the identification of a previously uncharacterized residue in the DNA-binding domain of PhoP, which is required for the transcriptional activation of PhoP regulated genes in Salmonella spp. Collectively our data demonstrate an interesting interface between the acquired SsrB regulon and the ancestral PhoPQ regulatory circuit, provide novel insights into the function of PhoP, and highlight a mechanism of regulatory integration of horizontally acquired genes into the virulence network of Salmonella enterica. © 2011 Gal-Mor et al.


LaPlante K.L.,University of Rhode Island | LaPlante K.L.,Brown University | Woodmansee S.,Infectious Diseases Research Laboratory | Mermel L.A.,Brown University | Mermel L.A.,Rhode Island Hospital
American Journal of Health-System Pharmacy | Year: 2012

Purpose. The compatibility and stability of telavancin and vancomycin in heparin or sodium citrate lock solutions were evaluated. Methods. Telavancin and vancomycin hydrochloride injection powder lyophilized for solution were reconstituted with 0.9% sodium chloride injection at room temperature according to the manufacturer's instructions and then further diluted with (1) commercially available heparin sodium to reach a final heparin concentration of 2500 units/mL or (2) sodium citrate solution 2.2% or 4% to achieve final telavancin and vancomycin concentrations of 2 and 5 mg/mL. Physical stability, chemical compatibility, and biological anticoagulant stability were analyzed for each antibiotic-anticoagulant combination immediately after preparation and at 24, 48, and 72 hours. Changes in coagulation were measured at each time point and compared using two-way analysis of variance. Results. Both telavancin and vancomycin retained at least 90% of the initial concentration after incubation at 37°C over 72 hours. The biological stability of vancomycin 2 mg/mL and telavancin 2 mg/mL did not significantly alter prothrombin time when compared with that of 0.9% sodium chloride injection. However, telavancin 5 mg/mL and vancomycin 5 mg/mL significantly increased the activated partial thromboplastin time at 72 hours compared with the control solution. Visual precipitation only occurred with vancomycin-containing solutions; however, this dissipated after 10 minutes. Conclusion. Telavancin 2 and 5 mg/mL was physically compatible in combination with heparin 2500 units/mL and with sodium citrate 2.2% and 4% over 72 hours. Vancomycin 2 and 5 mg/mL initially precipitated in the sodium citrate 2.2% formulation, but no precipitation was noted after 10 minutes of incubation at 37°C. Telavancin and vancomycin 2 and 5 mg/mL retained over 90% of the initial concentration after incubation at 37°C over 72 hours.


Gal-Mor O.,Infectious Diseases Research Laboratory | Suez J.,Infectious Diseases Research Laboratory | Suez J.,Tel Aviv University | Elhadad D.,Infectious Diseases Research Laboratory | And 8 more authors.
Clinical and Vaccine Immunology | Year: 2012

Enteric fever is an invasive life-threatening systemic disease caused by the Salmonella enterica human-adapted serovars Typhi and Paratyphi. Increasing incidence of infections with Salmonella enterica serovar Paratyphi A and the spreading of its antibiotic-resistant derivates pose a significant health concern in some areas of the world. Herein, we describe a molecular and phenotypic characterization of an S. Paratyphi A strain accounted for a recent paratyphoid outbreak in Nepal that affected at least 37 travelers. Pulsed-field gel electrophoresis analysis of the outbreak isolates revealed one genetic clone (pulsotype), confirming a single infecting source. Genetic profiling of the outbreak strain demonstrated the contribution of specific bacteriophages as a prime source of genetic diversity among clinical isolates of S. Paratyphi A. Phenotypic characterization in comparison with the S. Paratyphi A ATCC 9150 reference sequenced strain showed differences in flagellar morphology and increased abilities of the outbreak strain with respect to its motility, invasion into nonphagocytic cells, intracellular multiplication, survival within macrophages, and higher induction of interleukin-8 (IL-8) secreted by host cells. Collectively, these differences suggest an enhanced virulence potential of this strain and demonstrate an interesting phenotypic variation among S. Paratyphi A isolates. In vivo profiling of 16 inflammatory cytokines in patients infected with the outbreak strain revealed a common profile of a remarkable gamma interferon (IFN-γ) induction together with elevated concentrations of tumor necrosis factor alpha (TNF-α), IL-6, IL-8, IL-10, and IL-15, but not IL-12, which was previously demonstrated as elevated in nontyphoidal Salmonella infections. This apparent profile implies a distinct immune response to paratyphoid infections. Copyright © 2012, American Society for Microbiology. All Rights Reserved.


Elhadad D.,Infectious Diseases Research Laboratory | Elhadad D.,Tel Aviv University | McClelland M.,University of California at Irvine | Rahav G.,Infectious Diseases Research Laboratory | And 3 more authors.
Journal of Infectious Diseases | Year: 2015

Human infection with typhoidal Salmonella serovars causes a febrile systemic disease, termed enteric fever. Here we establish that in response to a temperature equivalent to fever (39°C-42°C) Salmonella enterica serovars Typhi, Paratyphi A, and Sendai significantly attenuate their motility, epithelial cell invasion, and uptake by macrophages. Under these feverlike conditions, the residual epithelial cell invasion of S. Paratyphi A occurs in a type III secretion system (T3SS) 1-independent manner and results in restrained disruption of epithelium integrity. The impaired motility and invasion are associated with down-regulation of T3SS-1 genes and class II and III (but not I) of the flagella-chemotaxis regulon. In contrast, we demonstrate up-regulation of particular Salmonella pathogenicity island 2 genes (especially spiC) and increased intraepithelial growth in a T3SS-2-dependent manner. These results indicate that elevated physiological temperature is a novel cue controlling virulence phenotypes in typhoidal serovars, which is likely to play a role in the distinct clinical manifestations elicited by typhoidal and nontyphoidal salmonellae. © 2014 The Author.


Yuhas Y.,Infectious Diseases Research Laboratory | Yuhas Y.,Tel Aviv University | Berent E.,Infectious Diseases Research Laboratory | Ashkenazi S.,Infectious Diseases Research Laboratory | And 2 more authors.
Inflammation Research | Year: 2014

Objective: Nitric oxide (NO) is a signaling molecule and regulator of immunity and inflammation. MicroRNAs (miRNAs) regulate gene transcription and are involved in inflammatory processes and cancer. This study sought to determine if NO activity affects miRNA expression. Methods: Human liver epithelial (HepG2) cells were treated with the NO-releasing S-nitroso-N- acetylpenicillamine (SNAP) 100 μM for 4 h and subjected to microarray analysis. To examine the underlying mechanisms, cells were exposed to cGMP analog 8-bromo-cGMP, protein kinase inhibitor Rp-*-Br-PET-cGMPS (Rp-PET), or nitric synthase inhibitor l-NAME and evaluated with RT-PCR. Results: MiR-155 was the only miRNA of the 887 arrayed that showed a change in expression after SNAP treatment. Incubation of the cells with 8-bromo-cGMP increased miR-155 expression 4.0 ± 0.7-fold (p < 0.05); Rp-PET before SNAP had a dual, concentration-dependent effect. SNAP treatment induced a 3.1 ± 0.7-fold change in miRNA-155 expression, Rp-PET 25 μM, a 7.3 ± 2.2-fold change, and Rp-PET 100 μM, a 0.79 ± 0.09-fold change (SNAP vs SNAP + Rp-PET, p < 0.05). In unstimulated cells, Rp-PET or l-NAME treatment increased miR-155 expression by 3.5 ± 0.7-fold and 5.6 ± 2.2-fold, respectively (p < 0.05). Conclusion: In HepG2 cells, exogenous NO increases miR-155 expression, but endogenous basal NO inhibits it. Both effects are mediated via cGMP/PKG signaling. The upregulation of miR-155 by NO provides a new link between NO, inflammation, and cancer. © 2014 Springer.


Elhadad D.,Infectious Diseases Research Laboratory | Elhadad D.,Tel Aviv University | Desai P.,University of California at Irvine | Rahav G.,Infectious Diseases Research Laboratory | And 4 more authors.
Infection and Immunity | Year: 2015

Salmonella enterica serovar Paratyphi A is a human-specific serovar that, together with Salmonella enterica serovar Typhi and Salmonella enterica serovar Sendai, causes enteric fever. Unlike the nontyphoidal Salmonella enterica serovar Typhimurium, the genomes of S. Typhi and S. Paratyphi A are characterized by inactivation of multiple genes, including in the flagellum-chemotaxis pathway. Here, we explored the motility phenotype of S. Paratyphi A and the role of flagellin in key virulence-associated phenotypes. Motility studies established that the human-adapted typhoidal S. Typhi, S. Paratyphi A, and S. Sendai are all noticeably less motile than S. Typhimurium, and comparative transcriptome sequencing (RNA-Seq) showed that in S. Paratyphi A, the entire motility-chemotaxis regulon is expressed at significantly lowers levels than in S. Typhimurium. Nevertheless, S. Paratyphi A, like S. Typhimurium, requires a functional flagellum for epithelial cell invasion and macrophage uptake, probably in a motility-independent mechanism. In contrast, flagella were found to be dispensable for host cell adhesion. Moreover, we demonstrate that in S. Paratyphi A, but not in S. Typhimurium, the lack of flagellin results in increased transcription of the flagellar and the Salmonella pathogenicity island 1 (SPI-1) regulons in a FliZ-dependent manner and in oversecretion of SPI-1 effectors via type three secretion system 1. Collectively, these results suggest a novel regulatory linkage between flagellin and SPI-1 in S. Paratyphi A that does not occur in S. Typhimurium and demonstrate curious distinctions in motility and the expression of the flagellumchemotaxis regulon between these clinically relevant pathogens. © 2015, American Society for Microbiology.


PubMed | Tel Aviv University and Infectious Diseases Research Laboratory
Type: Journal Article | Journal: Infection and immunity | Year: 2015

Salmonella enterica serovar Typhimurium is a facultative intracellular human and animal bacterial pathogen posing a major threat to public health worldwide. Salmonella pathogenicity requires complex coordination of multiple physiological and virulence pathways. DksA is a conserved Gram-negative regulator that belongs to a distinct group of transcription factors that bind directly to the RNA polymerase secondary channel, potentiating the effect of the signaling molecule ppGpp during a stringent response. Here, we established that in S. Typhimurium, dksA is induced during the logarithmic phase and DksA is essential for growth in minimal defined medium and plays an important role in motility and biofilm formation. Furthermore, we determined that DksA positively regulates the Salmonella pathogenicity island 1 and motility-chemotaxis genes and is necessary for S. Typhimurium invasion of human epithelial cells and uptake by macrophages. In contrast, DksA was found to be dispensable for S. Typhimurium host cell adhesion. Finally, using the colitis mouse model, we found that dksA is spatially induced at the midcecum during the early stage of the infection and required for gastrointestinal colonization and systemic infection in vivo. Taken together, these data indicate that the ancestral stringent response regulator DksA coordinates various physiological and virulence S. Typhimurium programs and therefore is a key virulence regulator of Salmonella.

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