Reinvestigation of the virulence of Rhodococcus equi isolates from patients with and without AIDS.

Rhodococcus equi emerged as a zoonotic pathogen of human immunodeficiency virus-infected patients over the last three decades. Two virulence plasmid types of R. equi, pVAPA and pVAPB associated with equine and porcine isolates, have been recognized, and more recently, pVAPN, a novel host-associated virulence plasmid in R. equi, was found in bovine and caprine isolates. We reinvestigated 39 previously reported isolates of R. equi from patients with and without acquired immunodeficiency syndrome (AIDS) by detecting vapA, vapB and vapN using PCR and plasmid profiling. After excluding one isolate that could not be cultured from frozen storage, eight isolates carried a virulence plasmid encoding vapA (pVAPA), 10 carried a virulence plasmid encoding vapB (pVAPB), seven carried a virulence plasmid encoding vapN (pVAPN) and 13 were negative for those genes. Of the 29 isolates from patients with AIDS, 7, 10 and 5 harboured pVAPA, pVAPB and pVAPN respectively. Among nine isolates from patients without AIDS, one and two harboured pVAPA and pVAPN respectively. This study demonstrated that pVAPN-positive R. equi existed in human isolates before 1994 and reaffirmed that equine-associated pVAPA-positive, porcine-associated pVAPB-positive and bovine- or caprine-associated pVAPN-positive R. equi are widely spread globally. Because domestic animals might be major sources of human infection, further research is needed to reveal the prevalence of pVAPN-positive R. equi infection in cattle and goats.

Rhodococcus induced false-positive galactomannan (GM), a biomarker of fungal presentation, in patients with peritoneal dialysis: case reports.

BACKGROUND: Galactomannan index (GMI) at a level higher than 0.5 provides high sensitivity and specificity for the diagnosis of fungal peritonitis. Here, we report the false-positive of GMI in peritoneal dialysis (PD) effluent (PDE) due to Rhodococcus peritonitis in PD patients. CASE PRESENTATION: GMI in PDE of case #1 and case #2 were 1.53 and 0.76, respectively, while serum GMI of both cases was less than 0.5. In addition, GMI from the specimens obtained directly from the stationary phase of Rhodococcus colonies were 1.27 and 1.56, which were isolated from case #1 and #2, accordingly. CONCLUSION: High GMI in PDE of PD patients is not specific just for fungal infections but may also be secondary to other infections, such as Rhodococcus spp., especially in endemic areas.

Isoprenoids increase bovine endometrial stromal cell tolerance to the cholesterol-dependent cytolysin from Trueperella pyogenes.

Preventing postpartum uterine disease depends on the ability of endometrial cells to tolerate the presence of the bacteria that invade the uterus after parturition. Postpartum uterine disease and endometrial pathology in cattle are most associated with the pathogen Trueperella pyogenes. Trueperella pyogenes secretes a cholesterol-dependent cytolysin, pyolysin, which causes cytolysis by forming pores in the plasma membrane of endometrial stromal cells. The aim of the present study was to identify cell-intrinsic pathways that increase bovine endometrial stromal cell tolerance to pyolysin. Pyolysin caused dose-dependent cytolysis of bovine endometrial stromal cells and leakage of lactate dehydrogenase into supernatants. Cell tolerance to pyolysin was increased by inhibitors that target the mevalonate and cholesterol synthesis pathway, but not the mitogen-activated protein kinase, cell cycle, or metabolic pathways. Cellular cholesterol was reduced and cell tolerance to pyolysin was increased by supplying the mevalonate-derived isoprenoid farnesyl pyrophosphate, or by inhibiting farnesyl-diphosphate farnesyltransferase 1 or geranylgeranyl diphosphate synthase 1 to increase the abundance of farnesyl pyrophosphate. Supplying the mevalonate-derived isoprenoid geranylgeranyl pyrophosphate also increased cell tolerance to pyolysin, but independent of changes in cellular cholesterol. However, geranylgeranyl pyrophosphate inhibits nuclear receptor subfamily 1 group H receptors (NR1H, also known as liver X receptors), and reducing the expression of the genes encoding NR1H3 or NR1H2 increased stromal cell tolerance to pyolysin. In conclusion, mevalonate-derived isoprenoids increased bovine endometrial stromal cell tolerance to pyolysin, which was associated with reducing cellular cholesterol and inhibiting NR1H receptors.

Thrombotic thrombocytopenic purpura-like syndrome associated with arcanobacterium pyogenes endocarditis in a post-transplant patient: A case report.

Systemic Arcanobacterium pyogenes is a rare bacterial infection in humans.1The diagnosis of thrombotic thrombocytopenic purpura (TTP)-like syndrome and infective endocarditis (IE) is often elusive. We report a case of TTP-like syndrome associated with A. pyogenes endocarditis in a post-allogenic transplant patient.

A Chinese patient with peritoneal dialysis-related peritonitis caused by Gordonia terrae: a case report.

BACKGROUND: Gordonia terrae is a rare cause of clinical infections, with only 23 reported cases. We report the first case of peritoneal dialysis-related peritonitis caused by Gordonia terrae in mainland China. CASE PRESENTATION: A 52-year-old man developed peritoneal dialysis-related peritonitis and received preliminary antibiotic treatment. After claiming that his symptoms had been resolved, the patient insisted on being discharged (despite our recommendations) and did not receive continued treatment after leaving the hospital. A telephone follow-up with the patient's relatives revealed that the patient died 3 months later. Routine testing did not identify the bacterial strain responsible for the infection, although matrix-assisted laser desorption/ionization time-of-flight mass spectrometry identified the strain as Gordonia rubropertincta. However, a 16S rRNA sequence analysis using an isolate from the peritoneal fluid culture revealed that the responsible strain was actually Gordonia terrae. Similar to this case, all previously reported cases have involved a delayed diagnosis and initial treatment failure, and the definitive diagnosis required a 16S rRNA sequence analysis. Changes from an inappropriate antibiotic therapy to an appropriate one have relied on microbiological testing and were performed 7-32 days after the initial treatment. CONCLUSIONS: The findings from our case and the previously reported cases indicate that peritoneal dialysis-related peritonitis caused by Gordonia terrae can be difficult to identify and treat. It may be especially challenging to diagnose these cases in countries with limited diagnostic resources.

Cardiovascular Implantable Electronic Device Infections due to Propionibacterium Species.

INTRODUCTION: Propionibacterium species are part of the normal skin flora and often considered contaminants when identified in cultures. However, they can cause life-threatening infections, including prosthetic cardiovascular device infections. Clinical presentation and management of cardiovascular implantable electronic device (CIED) infection due to Propionibacterium species has not been well described. METHODS: Retrospective review of all cases of CIED infection due to Propionibacterium species admitted to Mayo Clinic between January 1, 1990 and December 31, 2014. Patient charts were reviewed for clinical, microbiological, and imaging data. Descriptive analysis was performed. RESULTS: We identified 14 patients with CIED infection due to Propionibacterium species, accounting for 2.3% of all CIED infections. Patients were predominantly male (n = 12, 86%). The median age at admission was 58.5 years (range 22-83). Twelve patients had implantable cardioverter defibrillators (ICDs) and two had permanent pacemaker systems. Twelve patients had generator pocket infection (86%). Two patients met clinical criteria for CIED-related infective endocarditis. Median time between last device manipulation and infection was 9 months (range 1-98). All patients were treated with complete device removal and antibiotic therapy. Six-month follow-up data were available for 10 patients (71%), with no relapses documented. CONCLUSION: CIED infections due to Propionibacterium species accounted for 2.3% of all device infections over a 25-year period. The most common infectious syndrome was generator pocket infection with delayed onset. There was an unanticipated predominance of ICDs in this cohort. Cure was achieved in all cases with complete device removal and antibiotic therapy.

[Unusually infected sebaceous cyst by Dermabacter hominis]. / Un caso inusual de quiste sebáceo infectado por Dermabacter hominis.

Dermabacter hominis species is constituted by Gram positive facultative anaerobic coryneform rods being part of the resident microbiota human skin, and exceptionally associated to infections in immunocompromised or severely debilitated patients. An immunocompetent young adult woman with a neck sebaceous cyst infected by D. hominis as unique etiologic agent is presented. Phenotypic identification of the causative agent was achieved through simple tests, based on the originally scheme proposed by Funke and Bernard, and feasible to be performed in a hospital Microbiology Laboratory. Phenotypic characteristics as coccoid morphology, the acrid/spermatic odor, esculin hydrolysis, the production of pyrrolidonyl-arylamidase, lysine and ornithine decarboxylase, are key tests to identify D. hominis. The matrix-asisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) confirmed the phenotypic identification.

Plastic Expander-Related Gordonia Sputi Infection: Case Report and Literature Review.

Gordonia sputi causes rare bacterial infections resulting from a contaminated indwelling medical device. We report the case of a postoperative plastic expander abscess in a woman, with G. sputi identification by 16S ribosomal RNA sequencing. This report indicates that Gordonia spp. should be included in the list of organisms causing plastic implant infections.

Brain abscess due to Trueperella bernardiae.

We present the case of a brain abscess caused by a combination of rare organisms (Trueperella bernardiae and Peptoniphilus harei) in a patient with chronic suppurative otitis media that had been complicated by the presence of a cholesteatoma. The authors believe this is the first report published in the literature.

Peritoneal-dialysis related peritonitis caused by Gordonia species: report of four cases and literature review.

AIM: To investigate the clinical course and outcome of peritoneal dialysis-associated peritonitis secondary to Gordonia species. METHOD: We reviewed all Gordonia peritonitis episodes occurring in a single dialysis unit from 1994 to 2013. RESULTS: During the study period, four episodes of Gordonia peritonitis were recorded. All were male patients. One patient responded to vancomycin therapy. One patient had refractory peritonitis despite vancomycin, but responded to imipenem and amikacin combination therapy. One patient had relapsing peritonitis and required catheter removal. The fourth patient had an elective Tenckhoff catheter exchange. No patient died of peritonitis. Causative organism was not fully identified until 7 to 18 days of peritonitis. CONCLUSION: Gordonia species is increasingly recognized to cause serious infections. In patients undergoing peritoneal dialysis, Gordonia peritonitis should be considered in case of refractory Gram-positive bacilli peritonitis, especially when the exact organism could not be identified one week after the onset of peritonitis. A close liaison with a microbiologist is needed for a timely diagnosis.

Nonsurgical management of complicated splenic rupture in infectious mononucleosis.

We report on a 35-year-old man who presented to the emergency department with acute abdominal pain, postural hypotension, and tachycardia after having been diagnosed with Epstein-Barr virus infection 1 week before. Abdominal ultrasound and computed tomography revealed splenic rupture, and the patient underwent successful proximal angiographic embolization of the splenic artery. The course was complicated by painful splenic necrosis and respiratory insufficiency due to bilateral pleural effusions. Six weeks later, he additionally developed severe sepsis with Propionibacterium granulosum due to an intrasplenic infected hematoma, which required drainage. All complications were treated without surgical splenectomy, and the patient finally made a full recovery.

Orbital cellulitis complicated by central retinal artery occlusion.

The authors present a case of a 16-year-old boy who sought treatment in Storm Eye Institute for orbital cellulitis complicated by central retinal artery occlusion. He was examined for severe signs of orbital cellulitis, including decreased vision and an afferent pupillary defect. Intravenous antibiotics failed to provide timely improvement, and the patient was surgically managed with endoscopic orbital decompression. An ocular examination under anesthesia revealed retinal ischemia in the affected eye, and fluorescein angiography confirmed the diagnosis of central retinal artery occlusion. The patient's vision improved slightly following resolution of the infection. Central retinal artery occlusion is a rare complication of orbital cellulitis in adults and has yet to be reported in the pediatric population.

Late infections after dynamic stabilization of the lumbar spine with Dynesys.

INTRODUCTION: Dynamic stabilization of the spine was developed as an alternative to rigid fusion in chronic back pain to reduce the risk of adjacent segment degeneration. Dynamic neutralization system (Dynesys, Zimmer CH) is one of the most popular systems available, but some midterm studies show revision rates as high as 30 %. Some late infectious complications in our patients prompted us to review them systematically. Propionibacterium recently has been shown to cause subtle infections of prosthetic material. MATERIALS AND METHODS: Here, we report on a consecutive series of 50 Dynesys implants. In a median follow-up of 51 months (range 0-91), we identified 12 infectious and 11 non-infectious complications necessitating reoperation or removal of the implant in 17 patients. RESULTS: Material infections occurred after a median of 52 months (2-77) and were due to Propionibacterium alone (n = 4) or in combination (n = 3) in seven out of 11 patients. Clinical presentation combines new or increasing pain associated with signs of screw loosening on conventional X-rays; however, as many as 73.5 % of patients present some degree of screw loosening without being at all symptomatic of infection. CONCLUSION: The high rate of late infections with low-grade germs and the frequency of screw loosening signs made us suspect a lack of integration at the bone-screw interface. Surgeons should be suspicious if the patient presents a combination of new or increasing pain and signs of screw loosening, and aggressive revision is recommended in these cases.

[Secondary hypogammaglobulinemia with recurrent opportunistic pulmonary infection]. / Wiederholte opportunistische Infektionbei sekundärem Immunglobulinmangel.

Secondary hypogammaglobulinemia may be a relevant predisposing condition in patients with recurrent bacterial upper airway disease (pneumonia, sinusitis) or first-time opportunistic infection, particularly if additional immunosuppressive factors like underlying hematological disease or immunosuppressive therapy are present. As an example, we present a retired farmer with myeloma, treated Hodgkin-lymphoma and hypogammaglobulinemia suffering from the third episode of Rhodococcus equi pneumonia. Screening for hypogammaglobulinemia is recommended in patients with unexplained recurrent bacterial airway infection or first time opportunistic disease, particularly with micro-organisms controlled by humoral immunity. Screening should include the analysis of total immunoglobulin levels (IgA, IgG and IgM). If results are ambiguous, tetanus toxoid and pneumococcal polysaccharide vaccine should be administered with measurement of specific antibody titer before and one month after vaccination. An adequate antibody response largely excludes a clinically significant humoral immunodeficiency. If hypogammaglobulinemia is present in a patient with recurrent or opportunistic infections, periodical substitution of IVIG in a dose and frequency to prevent further infectious episodes should be initiated. This is usually achieved with an IVIG-dose of 0.4g/kg body weight every 3 - 4 weeks to reach a trough IgG-level of 5 - 7g/L.

[Infection due to Rhodococcus equi in HIV infected patients: four cases]. / Infección por Rhodococcus equi en pacientes infectados por virus de la inmunodeficiencia humana: descripción de cuatro casos.

INTRODUCTION: Incidence of Rhodococcus equi (R. equi) infection is increasing parallel to a greater prevalence of immunosupressed patients. This study aims to describe clinico-epidemiological characteristics of R. equi infections in a single hospital. METHODS: Retrospective, observational study that includes any patient diagnosed of R. equi infection during the 1999-2007 period. Clinical and epidemiological characteristics were recorded. RESULTS: Four patients were diagnosed of R. equi infection, with a mean age of 37.75+/-9.94 years old. All of them were male, infected with human immunodeficiency virus, and showed severe immunosuppression (mean CD4+ lymphocyte count of 83+/-55.2 cells/microl). Respiratory symptoms and cavitary pulmonary lesions were constantly present. R. equi was always cultured in blood and respiratory secretions. CONCLUSIONS: R. equi infection is a rare disease that occurs predominantly in HIV infected patients, severely immunosuppressed patients and almost always causes cavitary pneumonia.

The clinical importance of microbiological findings in the diagnosis and management of bloodstream infections.

Bloodstream infections are associated with high morbidity and mortality. Accurate identification of blood isolates to the species level and identification of the source of infection and/or the portal of entry are crucial for optimal management of these infections. These investigations-in addition to clinical findings and laboratory and imaging studies-are central to informing and directing efficient and effective diagnostic examinations and to choosing the optimal antimicrobial regimen. Four case studies that demonstrate the importance of identifying the causative agents and the source of infection are discussed to illustrate the central importance of microbiological findings in the diagnosis of bacteremia and bloodstream infections associated with infections at other sites.

Rhodococcus equi infection in a patient with spinocellular carcinoma of unknown origin.

A Rhodococcus equi pulmonary infection in a 63-year-old man receiving chemotherapy and radiotherapy for spinocellular carcinoma is described. The patient, a knife-grinder, was promptly treated with levofloxacin plus amikacin followed by rifampicin for 2 months, and he is still in good clinical condition after an 8-month follow-up.

Bacterial meningitis from Rothia mucilaginosa in patients with malignancy or undergoing hematopoietic stem cell transplantation.

Opportunistic infections contribute to morbidity and mortality of patients undergoing hematopoietic stem cell transplantation and treatment for malignancies. Rothia mucilaginosa, a gram-positive bacterium, is responsible for rare, but often fatal meningitis in severely immunocompromised patients. We describe two cases of meningitis from discrete strains of R. mucilaginosa on our pediatric bone marrow transplant unit, summarize the published cases of R. mucilaginosa meningitis in oncology and stem cell transplant patients, and provide updated recommendations regarding the use of antibiotic therapy in this patient population.