Project description:Mycoplasma genitalium is the causative agent of non-gonococcal, chlamydia-negative urethritis in men and has been linked to reproductive tract disease syndromes in women. As with other mycoplasmas, M. genitalium lacks many regulatory genes because of its streamlined genome and total dependence on a parasitic existence. Therefore, it is important to understand how gene regulation occurs in M. genitalium, particularly in response to environmental signals likely to be encountered in vivo. In this study, we developed an oligonucleotide-based microarray to investigate transcriptional changes in M. genitalium following osmotic shock. Using a physiologically relevant osmolarity condition (0.3 M sodium chloride), we identified 39 up-regulated and 72 down-regulated genes. Of the up-regulated genes, 21 were of unknown function and 15 encoded membrane-associated proteins. The majority of down-regulated genes encoded enzymes involved in energy metabolism and components of the protein translation process. These data provide insight into the in vivo response of M. genitalium to hyperosmolarity conditions and identify candidate genes that may contribute to mycoplasma survival in the urogenital tract.
Project description:Mycoplasma genitalium is the causative agent of non-gonococcal, chlamydia-negative urethritis in men and has been linked to reproductive tract disease syndromes in women. As with other mycoplasmas, M. genitalium lacks many regulatory genes because of its streamlined genome and total dependence on a parasitic existence. Therefore, it is important to understand how gene regulation occurs in M. genitalium, particularly in response to environmental signals likely to be encountered in vivo. In this study, we developed an oligonucleotide-based microarray to investigate transcriptional changes in M. genitalium following osmotic shock. Using a physiologically relevant osmolarity condition (0.3 M sodium chloride), we identified 39 up-regulated and 72 down-regulated genes. Of the up-regulated genes, 21 were of unknown function and 15 encoded membrane-associated proteins. The majority of down-regulated genes encoded enzymes involved in energy metabolism and components of the protein translation process. These data provide insight into the in vivo response of M. genitalium to hyperosmolarity conditions and identify candidate genes that may contribute to mycoplasma survival in the urogenital tract. To examine the effects of hyperosmolarity on M. genitalium transcription, four 50 ml cultures of strain G37 in 75 cm2 tissue culture flasks (Corning) were grown to exponential phase, as determined by medium colour change and colony density. Then, NaCl was added to three flasks to achieve final concentrations of 0.1, 0.2 and 0.3 M. Parallel cultures of M. genitalium in the absence of NaCl served as controls. All cultures were incubated for 1 h at 37M-bM-^DM-^C prior to RNA extraction. Experiments were repeated six times, which produced six independent RNA sample pairs from NaCl-treated cultures and control cultures for each NaCl condition. Dye swap was performed on three of six RNA pairs to minimize effects caused by biased labelling efficiencies.
Project description:Mycoplasma genitalium and M. pneumoniae are two significant mycoplasmas that infect the urogenital and respiratory tracts of humans. Despite distinct tissue tropisms, they both have similar pathogenic mechanisms and infect/invade epithelial cells in the respective regions and persist within these cells. However, the pathogenic mechanisms of these species in terms of bacterium-host interactions are poorly understood. To gain insights on this, we infected HeLa cells independently with M. genitalium and M. pneumoniae and assessed gene expression by whole transcriptome sequencing (RNA-seq) approach. The results revealed that HeLa cells respond to M. genitalium and M. pneumoniae differently by regulating various protein-coding genes. Though there is a significant overlap between the genes regulated by these species, many of the differentially expressed genes were specific to each species. KEGG pathway and signaling network analyses revealed that the genes specific to M. genitalium are more related to cellular processes. In contrast, the genes specific to M. pneumoniae infection are correlated with immune response and inflammation, possibly suggesting that M. pneumoniae has some inherent ability to modulate host immune pathways.
Project description:IntroductionInvasive infections due to Cellulosimicrobium spp. (a Gram-positive coryneform) are extremely rare. Only a few cases of bloodstream infections and endocarditis have been described, as bacteraemia due to coryneforms is usually discarded as blood culture contamination.Case presentationA 66-year-old female, with a history of aortic valve replacement, presented with fever, left leg purpura and acute kidney injury. Multiple repeated blood cultures were positive for Cellulosimicrobium cellulans , and targeted therapy was started. At first, endocarditis was excluded by echocardiograms, and the acute nephritis was interpreted as an atypical presentation of Henoch-Shönlein purpura. High-dose prednisone was started, and after 10 weeks the patient presented again with fever, mental confusion and acute left arm ischaemia. A subsequent echocardiogram and radiolabelled leukocyte scintigraphic evaluation revealed aortic prosthetic valve endocarditis with periprosthetic abscess and arterial brachial thrombosis. The patient deceased, and the autoptic examination confirmed an aortic valve periprosthetic abscess and revealed multiple arterial thromboses and septic embolisms in the kidneys, brain, spleen and myocardium.ConclusionIsolation of coryneform bacteria on blood culture should not always be discarded as blood culture contamination. In the case of endocarditis due to Cellulosimicrobium spp., the removal of any prosthetic material, along with prolonged in vitro active antimicrobial therapy, should be pursued in order to reduce persistence or relapses of infection.
Project description:BackgroundTranscatheter aortic valve implantation (TAVI) has emerged as an alternative for the treatment of severe symptomatic aortic stenosis for patients at high risk for open surgery. Although experience with TAVI is increasing, few cases of post-TAVI endocarditis are reported.Case summaryWe present a case of an 87-year-old female patient who presented with fever, unresponsive to empiric antibiotics 3 months after a TAVI procedure for severe aortic valve stenosis. After some delay due to three hospitalizations in primary care hospitals, she was transferred to our general intensive care unit where the diagnosis of endocarditis due to Corynebacterium was made. The patient was transferred abroad to a specialized surgical centre of excellence and underwent aortic root and valve replacement with a homograft. After several post-operative complications the patient's condition improved and is presently satisfactory.DiscussionKeeping a high index of suspicion when evaluating patients might lead to a favourable outcome if appropriate and early intervention was implemented. Adherence to policies which address infection control and aseptic techniques when performing TAVI might lead to fewer cases of post-TAVI endocarditis.
Project description:An 80-year-old male underwent a transcatheter aortic valve implantation (TAVI) for severe senile aortic stenosis. Six weeks after the surgery, he was readmitted to our institution because of a high-grade fever. Transesophageal echocardiography revealed thickening of all three leaflets of the aortic prosthesis and mobile mass on the leaflet, and Streptococcus sanguis was identified from his blood culture. Therefore, he was diagnosed with prosthetic valve endocarditis (PVE) and received intensive intravenous antibiotic therapy. Because he did not respond to the pharmacological therapy, surgical aortic valve replacement (AVR) was indicated although it was considered a relatively high-risk procedure. Herein, we report on the successful surgical AVR in this patient using a pericardial valve after removal of the infected prosthetic valve, and discuss some issues related to this rare complication after TAVI. <Learning objective: Transcatheter aortic valve implantation (TAVI) is a highly effective procedure for patients with symptomatic severe aortic stenosis who are at high risk or deemed inoperable. Because it only requires limited surgical invasiveness, the risk of prosthetic valve endocarditis (PVE) after TAVI is thought to be low. However, PVE can occur even early after TAVI. We present our recent such case and discuss some issues related to this rare complication.>.