Next Generation Sequencing Reveals the Expression of a Unique miRNA Profile in Response to a Gram-Positive Bacterial Infection.
Animal and Bioscience Research Department, Animal and Grassland Research and Innovation Centre, Teagasc, Grange, Dunsany, County Meath, Ireland ; School of Biochemistry and Immunology, Trinity College, Dublin, Ireland.
MicroRNAs (miRNAs) are short, non-coding RNAs, which post-transcriptionally regulate gene expression and are proposed to play a key role in the regulation of innate and adaptive immunity. Here, we report a next generation sequencing (NGS) approach profiling the expression of miRNAs in primary bovine mammary epithelial cells (BMEs) at 1, 2, 4 and 6 hours post-infection with , a causative agent of bovine mastitis. Analysing over 450 million sequencing reads, we found that 20% of the approximately 1,300 currently known bovine miRNAs are expressed in unchallenged BMEs. We also identified the expression of more than 20 potentially novel bovine miRNAs. There is, however, a significant dynamic range in the expression of known miRNAs. The top 10 highly expressed miRNAs account for >80% of all aligned reads, with the remaining miRNAs showing much lower expression. Twenty-one miRNAs were identified as significantly differentially expressed post-infectionwith . Several of these miRNAs have characterised roles in the immune systems of other species. This miRNA response to the Gram-positive is markedly different, however, to lipopolysaccharide (LPS) induced miRNA expression. Of 145 miRNAs identified in the literature as being LPS responsive, only 9 were also differentially expressed in response to . Computational analysis has also revealed that the predicted target genes of miRNAs, which are down-regulated in BMEs following infection, are statistically enriched for roles in innate immunity. This suggests that miRNAs, which potentially act as central regulators of gene expression responses to a Gram-positive bacterial infection, may significantly regulate the sentinel capacity of mammary epithelial cells to mobilise the innate immune system.
Labels: Gram-Positive Bacterial Infection, lipopolysaccharide, miRNA Profile, Next Generation Sequencing
Candida glabrata Prosthetic Hip Infection.
Consultant Physician, Infectious and Tropical Diseases Department, Azienda Ospedaliero-Universitaria Careggi, Florence, Italy. firstname.lastname@example.org.
We present a case of a 60-year-old Caucasian woman carrying a 2-year-old hip prosthesis infected by Candida glabrata dose-dependent susceptible to fluconazole and voriconazole. Resection arthroplasty was performed. Six weeks of caspofungin plus liposomal amphotericin combination therapy achieved joint sterilization and allowed a successfully reimplantation arthroplasty. In addition we review 9 cases of C. glabrata prosthetic joint infection described to date in the literature.
Labels: arthroplasty, Candida glabrata, caspofungin, Infection, liposomal amphotericin, Prosthetic Hip
Evaluation of diagnostic value of procalcitonin as a marker of neonatal bacterial infections.
Pathology department, Hamadan University of Medical Sciences, Hamadan, Iran.
KEYWORDS: Infection, Newborn, Predictive Value of Tests, Procalcitonin, Sensitivity, Specificity
This study tried to assess sensitivity, specificity, positive and negative predictive value of procalcitonin for diagnosis of neonatal bacterial infections.
This prospective cross sectional study was carried out during an 18-month period in NICU and neonatal wards of Besat Hospital in Hamedan province, Iran. 39 symptomatic infants with clinical and laboratory findings in favor of bacterialinfection with a positive blood, CSF, and/or supra pubic urine culture entered the study; 32 newborns without any bacterialinfection served as control group. Quantitative procalcitonin level ≥0.5 ng/ml was accepted as pathological. Finally sensitivity, specificity, positive (PPV) and negative predictive value (NPV) were calculated for procalcitonin test.
20 blood cultures, 17 urine cultures and 8 CSF cultures were positive. Sensitivity, specificity, PPV and NPV for procalcitonin test was 76.9%, 100%, 100% and 78% respectively. Diagnostic value of procalcitonin test in accordance with blood culture for mentioned items was 85%, 100%, 100% and 91.4% respectively. Its diagnostic value according to urine culture was: sensitivity 70.6%, specificity 100%, PPV 100% and NPV 86.4%, and according to CSF culture was: sensitivity 75%, specificity 100%, PPV 100% and NPV 94.1% respectively.
The results show that the procalcitonin test has high sensitivity, specificity, PPV and NPV for diagnosis of neonatal infections.
Labels: blood cultures, Infection, newborn, Predictive Value of Tests, Procalcitonin, Sensitivity, Specificity, urine cultures
Role of Bacterial Lipopolysaccharide in Enhancing Host Immune Response to Candida albicans.
Tissue Engineering and Reparative Dentistry, School of Dentistry, College of Biomedical and Life Sciences, Cardiff University, Heath Park, Cardiff CF14 4XY, UK.
Human infections involving yeast of the genus Candida often occur in the presence of bacteria, and, as such, it is important to understand how these bacteria influence innate host immunity towards Candida. Dectin-1 is a cell receptor of macrophages for Candida albicans recognition. The aim of this study was to examine dectin-1 expression by monocytes after stimulation with bacterial lipopolysaccharide (LPS), followed by heat-killed C. albicans (HKC). Freshly isolated human peripheral blood monocytes (PBMCs) and human monocytes cell line (THP-1) cells expressed low levels of dectin-1. Stimulation with LPS and GM-CSF/IL-4 was found to increase dectin-1 expression in both CD14(+) human PBMC and THP-1 cells. Enhanced dectin-1 expression resulted in increased phagocytosis of Candida. When THP-1 cells were challenged only with HKC, detectable levels of IL-23 were not evident. However, challenge by LPS followed by varying concentrations of HKC resulted in increased IL-23 expression by THP-1 cells in HKC dose-dependent manner. Increased expression of IL-17 by PBMC also occurred after stimulation with Candida and LPS. In conclusion, bacterial LPS induces an enhanced immune response to Candida by immune cells, and this occurs through increasing dectin-1 expression.
Labels: Bacterial Lipopolysaccharide, Candida albicans, Dectin-1, Host Immune Response, human monocytes cell line, peripheral blood monocytes
A case of mycoplasma hominis infection on chronic refractory lower leg ulceration caused by livedo vasculopathy
[Article in Japanese]
Clinical Laboratory Department, St. Luke's International Hospital, Chuo-ku, Tokyo 104-8560, Japan. email@example.com
Mycoplasma hominis is a common inhabitant of the human urogenital tract and most frequently causes diseases of the genitourinary tract. Extragenital M. hominis infections are uncommon, with almost all occurring in immunosuppressed persons or those predisposed due to surgery or trauma. We report a case of non surgical, non-traumatic wound infectioncaused by M. hominis. A 28-year-old immunocompetent woman with livedo vasculopathy had an open wound on dorsum of her right foot with signs and symptoms of infection. However, gram staining of the wound swab demonstrated no microorganisms, and initial bacterial cultures did not reveal any microbial growth. After 2 days of culture, minute translucent colonies were appeared and subsequently identified as M. hominis. She was successfully treated with levofloxacin(LVFX). For the patient's being immune-competent, this infection seems to need a substantial bacterial transfer from the inhabitant organ. The transfer is likely mediated by the fluid's drop, for anatomical locations of vagina and the infection site on leg. Namely, the hinder leg infection is suspected to be caused by continual and heavy bacterial exposure originated from the vaginal M. hominis. This clinical case suggests that infections may occur even in normal immunological status if the site is close to, and lacks anatomical barrier from, the M. hominis inhabitant organ. Especially in infection at chronic refractory lower leg ulceration, M. hominis should be considered as a causative organism.
Labels: human urogenital tract, immunocompetent, Infection, levofloxacin, livedo vasculopathy, lower leg ulceration, LVFX, mycoplasma hominis
Carbon Catabolite Control in Candida albicans: New Wrinkles in Metabolism.
Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston, Houston, Texas, USA.
Most microorganisms maintain strict control of nutrient assimilation pathways to ensure that they preferentially use compounds that generate the most energy or are most efficiently catabolized. In doing so, they avoid potentially inefficient conflicts between parallel catabolic and metabolic pathways. The regulation of carbon source utilization in a wide array of bacterial and fungal species involves both transcriptional and posttranscriptional mechanisms, and while the details can vary significantly, carbon catabolite control is widely conserved. In many fungi, the posttranslational aspect (carbon catabolite inactivation [CCI]) involves the ubiquitin-mediated degradation of catabolic enzymes for poor carbon sources when a preferred one (glucose) becomes available.
A recent article presents evidence for a surprising exception to CCI in the fungal pathogen Candida albicans, an organism that makes use of gluconeogenic carbon sources during infection (D. Sandai, Z. Yin, L. Selway, D. Stead, J. Walker, M. D. Leach, I. Bohovych, I. V. Ene, S. Kastora, S. Budge, C. A. Munro, F. C. Odds, N. A. Gow, and A. J. Brown, mBio 3:e00495-12). In vitro, addition of glucose to cells grown in a poor carbon source rapidly represses transcripts encoding gluconeogenic and glyoxylate cycle enzymes, such as phosphoenolpyruvate carboxykinase (Pck1p) and isocitrate lyase (Icl1p), in both C. albicans and Saccharomyces cerevisiae.
Yet, uniquely, the C. albicans proteins persist, permitting parallel assimilation of multiple carbon sources, likely because they lack consensus ubiquitination sites found in the yeast homologs. Indeed, the yeast proteins are rapidly degraded when expressed in C. albicans, indicating a conservation of the machinery needed for CCI. How this surprising metabolic twist contributes to fungal commensalism or pathogenesis remains an open question.
Labels: Candida albicans, Carbon Catabolite, catabolic enzymes, glyoxylate cycle enzymes, Metabolism
Infections Succumbs to Blue Light
Blue light can selectively eradicate Pseudomonas aeruginosa infections of the skin and soft tissues, while preserving the outermost layer of skin, according to a proof-of-principle study led by Michael R. Hamblin of the Massachusetts General Hospital, and the Harvard Medical School in Boston. The research is published online ahead of print in the journal Antimicrobial Agents and Chemotherapy.
"Blue light is a potential non-toxic, non-antibiotic approach for treating skin and soft tissue infections, especially those caused by antibiotic resistant pathogens," says Hamblin.
In the study, animal models were infected with P. aeruginosa. All of the animals in the group treated with blue light survived, while in the control, 82 percent (9 out of 11) of the animals died.
Skin and soft tissue infections are the second most common bacterial infections encountered in clinical practice, and represent the most common infection presentation—more than 3 percent—in patients visiting emergency departments, says Hamblin. The prevalence of skin and soft tissue infections among hospitalized patients is 10 percent, with approximately 14.2 million ambulatory care visits every year and an annual associated medical cost of almost $24 billion (equivalent to $76 for every American), says Hamblin.
Treatment of skin and soft tissue infections has been significantly complicated by the explosion of antibiotic resistance, which may bring an end to what medical scientists refer to as the antibiotic era, says Hamblin. "Microbes replicate very rapidly, and a mutation that helps a microbe survive in the presence of an antibiotic drug will quickly predominate throughout the microbial population. Recently, a dangerous new enzyme, NDM-1, that makes some bacteria resistant to almost all antibiotics available has been found in the United States. Many physicians are concerned that several infections soon may be untreatable."
Besides harming public health, antibiotic resistance boosts health care costs. "Treating resistant skin and soft tissue infections often requires the use of more expensive, or more toxic drugs, and can result in longer hospital stays for infected patients," says Hamblin.
Reference: Dai T, Gupta A, et al. 2013. Blue light rescues mice from potentially fatal Pseudomonas aeruginosa burn infection: efficacy, safety, and mechanism of action. Antim. Agents Chemother. Published ahead of print Dec. 21, 2012 ,doi:10.1128/AAC.01652-12)
Labels: Antibiotic resistance, blue light, enzyme, Infection, NDM-1, Pseudomonas aeruginos, skin infections, soft tissue infections, treatment
A systematic review of validation studies of the use of administrative data to identify serious infections.
Formerly a the Division of Rheumatology, Department of Medicine, University Health Network, and the Division of Health Care and Outcome Research, Toronto Western Research Institute, University of Toronto, Toronto, Ontario, Canada; Division of Rheumatology, Department of Medicine, University of Calgary. cehbarbe@ucalgaryca.
To conduct a systematic review of the literature on the validation of algorithms identifying infections in administrative data for future use in populations with rheumatic diseases.
Medline and Embase were searched using the themes "administrative data" and "infection", between 1950 to October 2012. Inclusion criteria: validation studies of administrative data identifying infections in adult populations. Article quality was assessed using a validated tool.
5941 articles were identified, 90 articles underwent detailed review and 24 studies were included. The majority (17/24) examined bacterial infections and nine examined opportunistic infections. Eighteen studies were from the United States and all but four studies used ICD-9 codes. Rheumatoid arthritis patients were studied in 6/24. The studies on bacterial infections in general reported highly variable sensitivity and PPV for the diagnosis of infections using administrative data (sensitivity range 4.4-100%, PPV range 21.7-100%). Algorithms to identify opportunistic infections similarly had a highly variable sensitivity (range 20-100%) and PPV (1.3-99%). Thirteen studies compared the diagnostic accuracy of different algorithms which revealed that strategies including comprehensive algorithm using a greater number of diagnostic codes or codes in any position had the highest sensitivity for the diagnosis of infection. Algorithms which incorporated microbiologic or pharmacy data in combination with diagnostic codes had improved PPV for identification of tuberculosis.
Algorithms for identifying infections using administrative data should be selected based on the purpose of the study with careful consideration as to whether a high sensitivity or PPV is required.
Labels: Infections, validation studies