Combined ramR mutation and presence of a Tn1721-associated tet(A) variant in a clinical isolate of Salmonella enterica serovar Hadar resistant to tigecycline.

A Salmonella enterica serovar Hadar strain resistant to tigecycline (MIC, 16 microg/ml) was isolated. Molecular characterization revealed the presence of a plasmid-borne tet(A) variant associated with Tn1721 mediating a rise of the MIC for tigecycline when transferred to Escherichia coli. Additionally, a truncating mutation in ramR was detected. Transformation with wild-type ramR but not with the mutated ramR lowered the MIC for tigecycline. Characterization of this Salmonella isolate implicates ramR in resistance to tigecycline.

ramR mutations in clinical isolates of Klebsiella pneumoniae with reduced susceptibility to tigecycline.

Five Klebsiella pneumoniae isolates with reduced susceptibility to tigecycline (MIC, 2 microg/ml) were analyzed. A gene homologous to ramR of Salmonella enterica was identified in Klebsiella pneumoniae. Sequencing of ramR in the nonsusceptible Klebsiella strains revealed deletions, insertions, and point mutations. Transformation of mutants with wild-type ramR genes, but not with mutant ramR genes, restored susceptibility to tigecycline and repressed overexpression of ramA and acrB. Thus, this study reveals a molecular mechanism for tigecycline resistance in Klebsiella pneumoniae.

A review of German Scedosporium prolificans cases from 1993 to 2007.

Scedosporium prolificans is one of the most life-threatening fungal opportunistic pathogens due to its high resistance to common systemic antifungal agents. While a close relative of Pseudallescheria boydii, S. prolificans has a more limited geographic range being primarily found in Australia, USA and Spain. Infections have also been reported from several other European countries and from Chile. Twenty patients with Scedosporium prolificans infection or colonization from August 1993 to May 2007 were retrospectively reviewed in Germany. They had all been identified at or reported to the Reference Laboratory for Pseudallescheria/Scedosporium spp. in Berlin. Twelve of 13 patients with haematological disorders and/or on immunosuppressive therapy developed a fatal invasive scedosporiosis. Colonization of the respiratory tract was reported for one patient after heart-lung-transplantation, all six patients with cystic fibrosis and one with chronic sinusitis. Molecular studies of the S. prolificans isolates confirmed that parts of the 18S, the Internal Transcribed Spacer (ITS) regions and the D1/D2 domain of the 28S region of rDNA are monomorphic. However, sequencing of parts of the translation elongation factor EF1-alpha (EF-1alpha) and the chitin synthase (CHS-1) genes revealed the presence of three and two distinct genotypes, respectively. Two informative mutations were found in EF-1alpha and a single nucleotide exchange in the CHS-1 gene.

EBV reactivation and post transplant lymphoproliferative disorders following allogeneic SCT.

Fatal problems encountered in allogeneic stem cell transplantation include EBV reactivation and post transplant lymphoproliferative disorders (PTLDs) with high mortality rates. We performed a retrospective analysis in all consecutive adult and pediatric EBV reactivations and PTLD during a period of 8.5 years. There were 26 patients with EBV reactivation/PTLD out of a total of 854 transplantations giving an overall incidence of 3.0%. Specifically, the incidence of EBV-PTLD was 1.3%, whereas that of EBV reactivation was 1.8%. Median age was 46.0 and 11.0 years in the adult and pediatric patients, respectively. There were high rates (54%) of concomitant bacterial, viral, fungal and parasitic infections at the time of EBV manifestation. Variable treatment regimens were applied including in most cases an anti-CD20 regimen often in combination with virustatic compounds, polychemotherapy or donor lymphocytes. The mortality rates were 9 of 11 (82%) in patients with EBV-PTLD and 10 of 15 (67%) in patients with reactivation. Only 7 of 26 patients (27%) are alive after a median follow-up of 758 days (range 24-2751). The high mortality rates of EBV reactivation and of EBV-PTLD irrespective of multimodal treatment approaches emphasize standardization and optimization of post transplant surveillance and treatment strategies to improve control of these often fatal complications.

Expression and functional characterization of gfpmut3.1 and its unstable variants in Staphylococcus epidermidis.

Reporter gene systems are an invaluable tool for investigation of gene transcription activity in eukaryotes and prokaryotes. In order to analyze the temporal and spatial resolution of gene expression patterns in situ and for quantitatively investigating gene expression, the green fluorescent protein (GFP) appears to be especially useful. GFP has been broadly used in various bacterial species, however, there is only limited knowledge about key biological properties in S. epidermidis. Here, the crucial influence of different ribosomal binding sites (RBS) on gfpmut3.1 translation initiation in S. epidermidis 1457 is demonstrated. Only by using the RBS of the delta-hemolysin promoter, after 24 hours a strong fluorescence signal was obtained. The half-life of GFPmut3.1 in S. epidermidis 1457 was significantly shorter than in E. coli (7 h vs. 24 h). GFPmut3.1 derivatives with shorter half-lives (GFP(AAV) and GFP(ASV)) did not reach sufficient quantitative protein levels, and the resulting low fluorescence limits their use as reporter genes in S. epidermidis. This work provides fundamental insights into gfpmut3.1 expression in S. epidermidis and describes the crucial determinants of its biological behavior in this species. In general, this study underlines the need to accurately characterize key biological properties of this transcription marker in gram-positive hosts.

Presentation by scanning electron microscopy of the life cycle of microsporidia of the genus Encephalitozoon.

This paper presents, for the first time, documentation by detailed scanning electron microscopy of the life cycle of microsporidia of the genus Encephalitozoon. Phase 1 is represented by the extracellular phase with mature spores liberated by the rupture of host cells. To infect new cells the spores have to discharge their polar filament. Spores with everted tubes show that these are helically coiled. When the polar tubules have started to penetrate into a host cell they are incomplete in length. The infection of a host cell can also be initiated by a phagocytic process of the extruded polar filament into an invagination channel of the host cell membrane. After the penetration process, the tube length is completed by polar tube protein which passes through the tube in the shape of swellings. A completely discharged polar tube with its tip is also shown. The end of a polar tube is normally hidden in the cytoplasm of the host cell. After completion of the tube length the transfer of the sporoplasm occurs and phase 2 starts. Phase 2 is the proliferative phase, or merogony, with the intracellular development of the parasite that cannot be documented by scanning electron microscopy. The subsequent intracellular phase 3, or sporogony, starts when the meronts transform into sporonts, documented as chain-like structures which subdivide into sporoblasts. The sporoblasts finally transform directly into spores which can be seen in their host cell, forming bubble-like swellings in the cell surface.

Antimycotic therapy with liposomal amphotericin-B for patients undergoing bone marrow or peripheral blood stem cell transplantation.

Suspected deep or systemic mycosis in patients undergoing high-dose therapy and autologous or allogeneic bone marrow transplantation (BMT) requires an immediate systemic antimycotic therapy. Intravenous therapy with the standard drug conventional amphotericin-B is associated with severe adverse effects like nephrotoxicity and chills. Furthermore, BMT patients often receive other potential nephrotoxic drugs such as CsA or virustatics. In this study, we report 74 BMT-patients treated with liposomal amphotericin-B for culture-documented aspergillosis (n = 5) or candidiasis (n = 6), or for serologically (n = 35) or clinically suspected mycosis or as prophylaxis (n = 2). Therapy was initiated with a median dose of 2.8 (0.64-5.09) mg/kg body-weight and continued for 13 (1-55) days. The drug was excellently tolerated and only in one was therapy stopped due to severe chills and fever. Severe organ impairment was not observed under therapy with liposomal amphotericin-B. Creatinine decreased in five patients after an increase under preceding therapy with the conventional formulation. Influence of liposomal amphotericin-B on bilirubin and transaminases was difficult to evaluate due to therapy-related toxicity, veno-occlusive disease (VOD), and graft-versus-host disease (GvHD). 10/11 culture-positive patients died from aspergillosis (5/5) or candidiasis (5/6), but in 9/11 of these subjects the immunity was additionally compromised by GvHD, steroid therapy, and VOD. Liposomal amphotericin-B was effective in preventing relapse of systemic mycosis in 10/12 patients with a history of aspergillosis (n = 11) or candidiasis (n = 1). We conclude, that favourable toxicity of liposomal amphotericin-B should encourage dose escalation studies of liposomal amphotericin-B randomised against the conventional formulation and that the comparison of patients undergoing BMT with patients under standard chemotherapy might be difficult because of additional risk factors of the BMT-patients.

Pathology of microsporidiosis: emerging parasitic infections in patients with acquired immunodeficiency syndrome.

OBJECTIVE: Microsporidiosis is a group of rapidly emerging protozoan infections that have thus far been reported predominantly from severely immunosuppressed persons with the acquired immunodeficiency syndrome (AIDS). The four genera that have been identified in AIDS patients (Enterocytozoon, Encephalitozoon, Septata, and Pleistophora) are an increasingly common source of both localized and disseminated infections. However, the clinical and pathologic features of these agents are being described with such rapidity that many pathologists are unaware of the histologic, immunologic, and molecular methods for diagnosing these infections. This article summarizes the clinical and morphologic spectrum of the microsporidian species that infect patients with AIDS. Additionally, the role of ultrastructural, immunologic, tissue culture, and molecular techniques for the diagnosis of microsporidian infections are discussed. DATA SOURCES: Clinical and pathologic findings were obtained from patients with AIDS who were evaluated for microsporidian infections at the Grady Memorial Hospital in Atlanta. Selected laboratory studies were performed at the Division of Parasitic Diseases of the Centers for Disease Control and Prevention and at the Department of Physiology at Morehouse University. Additionally, some cases were sent for consultation to the Infectious Disease Pathology service at Emory University. These data were combined with the published studies of microsporidian infection from the medical literature. DATA SYNTHESIS: The pathologic appearance of microsporidian infections in each major organ system (ocular, respiratory, genitourinary, gastrointestinal) is illustrated using routine and special histochemistry and immunofluorescence. The differential diagnostic features of the four genera of microsporidia infecting AIDS patients are illustrated using transmission and scanning electron micrographs from biopsy, autopsy, and tissue culture materials. Cytologic evaluation of body tissues is emphasized as a sensitive method for microsporidian diagnosis. CONCLUSIONS: Microsporidian infections can be expected to remain an increasingly important cause of morbidity and mortality in patients with AIDS. It is important that pathologists and microbiologists become acquainted with the clinicopathologic spectrum of these emerging protozoal infections, ensuring timely diagnosis and subsequent treatment.

Visceral leishmaniasis emerging as an important opportunistic infection in HIV-infected persons living in areas nonendemic for Leishmania donovani.

BACKGROUND: Visceral leishmaniasis is an important infection in patients infected with human immunodeficiency virus and living in areas endemic for Leishmania sp. Leishmaniasis, however, is rarely suspected in patients residing in nonendemic countries. METHODS: Retrospective case analysis of 15 patients with human immunodeficiency virus infection and leishmaniasis treated at seven German clinics. The clinicopathological features and the diagnostic role of biopsy and/or cytology as compared to serology were evaluated. RESULTS: All patients were severely immunocompromised. One patient was first diagnosed at autopsy. One patient with mucocutaneous disease was diagnosed by nasal biopsy. All others had amastigotes detected in bone marrow (13/13), liver (3/3), and gastrointestinal mucosa (4/4). Serology was positive in only 6 or 13. CONCLUSION: Visceral leishmaniasis is an important opportunistic infection in patients with acquired immunodeficiency syndrome and it must be ruled out in every patient with fever and/or pancytopenia and an appropriate travel history. Because serological diagnosis is often insufficient, pathologists must be aware of the association between human immunodeficiency virus infection and leishmaniasis. Diagnosis depends on detection of the parasite in submitted specimens.

Diagnosis of Enterocytozoon bieneusi (microsporidia) infections by polymerase chain reaction in stool samples using primers based on the region coding for small-subunit ribosomal RNA.

OBJECTIVE: Enterocytozoon bieneusi is the most prevalent microsporidian causing chronic diarrhea in patients with acquired immunodeficiency syndrome. The current methods used for routine diagnosis of infections caused by microsporidia are based on microscopic detection of the microorganism spores in stained smears. We evaluated the usefulness of the polymerase chain reaction (PCR) technique as a tool to diagnose Enterocytozoon bieneusi infections, using the species-specific diagnostic primer pair EBIEF1/EBIER1 on stool samples that were also analyzed by optical microscopy. DESIGN: To perform PCR in such samples, we developed a novel protocol to obtain DNA free of PCR inhibitors. This protocol was based on disruption of spores using glass beads and overnight digestion with proteinase K; final purification was accomplished with the RapidPrep Micro Genomic DNA isolation Kit for Cells and Tissues (Pharmacia Biotech Inc, Piscataway, NJ). We also evaluated this approach on aliquots of a sample fixed in formalin from 1 to 10 days. PATIENTS AND SAMPLES: We evaluated the PCR technique on 64 stool samples obtained from patients with acquired immunodeficiency syndrome who had persistent chronic diarrhea. Patients were from Spain, Brazil, Germany, and the United States. RESULTS: Using this approach, we could confirm the presence of E bieneusi in all 17 positive samples; no false-positive results were observed. We could also amplify E bieneusi DNA in 10 aliquots of one sample fixed up to 10 days in 10% formalin. CONCLUSION: We conclude that PCR technology is very suitable for species identification of microsporidia in stool samples and may have a potential application in prospective studies in formalin-fixed samples.

Nosocomial outbreak of vancomycin-resistant Enterococcus faecium at a German university pediatric hospital.

Nosocomial Infections caused by vancomycin-resistant enterococci (VRE) are an emerging threat to critically ill patients. At the University Hospital Eppendorf, VRE were isolated from 38 patients between August 1993 and April 1997, of whom 32 were hospitalized at the Department of Pediatrics. Pulsed-field gel electrophoresis revealed that 26 Enterococcus faecium isolates from patients of the Department of Pediatrics were identical or closely related, and that isolates from three additional patients of the same department were possibly related. All of these isolates were of vanA genotype. They were resistant to glycopeptides, ampicillin, ciprofloxacin, clindamycin, and erythromycin. Most isolates displayed high-level resistance to gentamicin, but all remained susceptible to quinupristin/dalfopristin. Implementation of stringent hand disinfection and environmental disinfection policies, as well as measures for patient isolation contained this first outbreak of VRE at a German Children's hospital, which emphasizes the importance of hygienic measures for the control of nosocomial spread of these organisms.

Genomic tandem repeat analysis proves laboratory-acquired brucellosis in veterinary (camel) diagnostic laboratory in the United Arab Emirates.

We report a case of a 64-year-old veterinarian working in a state camel veterinary laboratory who was diagnosed with and treated for acute brucellosis with complicating epididymo-orchitis. Genomic tandem repeat analysis (MLVA-16) revealed identical Brucella strains in patient cultures and from different dromedary milk samples positive for Brucella melitensis, thereby confirming the diagnosis of a laboratory acquired infection. The case illustrates the high (airborne) infectivity of brucellosis in laboratory settings and the need to implement vigorous bio-safety measures in veterinary laboratories handling camel specimen diagnostic veterinary laboratory.

Molecular characterisation of linezolid resistance in two vancomycin-resistant (VanB) Enterococcus faecium isolates using Pyrosequencing.

In this paper, we describe the phenotypic and molecular characteristics of two clinically relevant, vancomycin-resistant (VanB), linezolid-resistant Enterococcus faecium isolates. Pyrosequencing showed the G to T single nucleotide polymorphism at bp 2576 in the genes coding for 23S rRNA and was used to quantify the proportion of G to T mutations among six different 23S rRNA genes in E. faecium as a marker for the molecular level of resistance to linezolid. In both isolates, the G to T mutation was found in two of six alleles, and no further mutations in the genes coding for 23S rRNA were found. The dynamic process of linezolid resistance could be demonstrated by the complete reversion of resistant alleles back to only wild type alleles in consecutive isolates of one isolate. Pyrosequencing being used to detect and quantify resistance to linezolid has been proven as a fast and reliable molecular screening method for monitoring linezolid resistance.

[Severe colitis due to Histoplasma capsulatum in an AIDS patient]. / Schwere Kolitis durch Histoplasma capsulatum bei einer Patientin mit Aids.

The case of a thirty-two-year-old female HIV-positive patient from Ghana admitted with a septic illness, diarrhoea, anaemia, and severe weight loss is presented. During an extensive diagnostic work-up Mycobacterium tuberculosis infection and typhoid fever were detected. Specific treatment led to marked improvement in the patient's condition. However, five weeks later high fever and diarrhoea recurred. Histological examination of biopsies from coloscopy and blood cultures revealed Histoplasma capsulatum. The patient recovered completely following antifungal therapy with amphotericin B and itraconazole. The case presented emphasises the need for medical staff dealing with immunocompromised patients from endemic areas to be aware of symptoms, diagnostic features, and therapeutic measures of this rare fungal infection.

Phenotypic detection of beta-lactamase-mediated resistance to oxyimino-cephalosporins in Enterobacteriaceae: evaluation of the Mastascan Elite Expert System.

OBJECTIVES: The aim of this study was to evaluate phenotypic detection of beta-lactamase-mediated resistance to oxyimino-cephalosporins in Enterobacteriaceae using the Mastascan Elite Expert System challenged with a battery of genotypically characterized organisms. METHODS: Isolates (n = 120) were identified to species level and antimicrobial susceptibilities were determined using agar incorporation methods and Mastascan Elite. Phenotypes were examined using an Expert System (ES) and putative genotypes were suggested using interpretative reading. RESULTS: Identification was correct in 119 of 120 isolates. The ES was able to identify the correct beta-lactam phenotype (as deduced from molecular methods) in a single choice in 98 of 120 (81.7%) isolates. In an additional 15 (12.5%) cases, the ES identified the correct beta-lactam phenotype within two or more choices. The detected phenotype was incorrect in seven (5.8%) isolates, but three of these were not inherent to the ES. CONCLUSIONS: The Mastascan Elite ES is relatively inexpensive and flexible and can identify the mechanism of resistance to oxyimino-cephalosporins in the majority of Enterobacteriaceae without recourse to molecular methods.

Comparative in vitro activity of fleroxacin, two other quinolones and three board-spectrum beta-lactams using the E-Test.

The in vitro activity of fleroxacin was compared to that of ciprofloxacin, ofloxacin and three broad-spectrum beta-lactams against 159 clinical isolates using the E-Test. Fleroxacin, ciprofloxacin, and ofloxacin were all active against Enterobacteriaceae with 93, 98 and 94% susceptibility, respectively. For other gram-negative strains, 81% were susceptible to fleroxacin and ofloxacin and 98% to ciprofloxacin. With regard to gram-positive strains, 72% were susceptible to fleroxacin, 83% to ciprofloxacin and 78% to ofloxacin. The broad antibacterial activity suggests that fleroxacin may be an alternative in the treatment of various infections, particularly in light of its favorable pharmacokinetics.

Virulence factors of Enterococcus faecalis and Enterococcus faecium blood culture isolates.

Known and potential virulence factors of enterococcal blood culture isolates were studied using 89 Enterococcus faecalis and 24 Enterococcus faecium isolates. The prevalence of the respective factors was (Enterococcus faecalis vs. Enterococcus faecium): hemolysin 16% vs. 0%, gelatinase 55% vs. 0%, aggregation substance 63% vs. 13%, lipase 35% vs. 4%, hemagglutinin 97% vs. 0%. Deoxyribonuclease was not detected in any isolate. The study showed that hemagglutinin and lipase may represent additional virulence factors of Enterococcus faecalis but not Enterococcus faecium. The significance of these factors in the pathogenesis of enterococcal infection needs to be elucidated in further studies.

Dual microsporidial infection with Encephalitozoon cuniculi and Enterocytozoon bieneusi in an HIV-positive patient.

This report describes the first dual microsporidial infection with Encephalitozoon cuniculi and Enterocytozoon bieneusi in an HIV-positive patient. In view of clinical and epidemiological findings, our E. cuniculi isolate was deduced to be of the dog strain. The patient's occupational involvement with dogs indicates that canines should be considered as a reservoir of human infections for both microsporidial species. Furthermore, our report provides detailed clinical and radiological information on a rare case of a symptomatic pulmonary infection by E. cuniculi and its improvement after treatment with albendazole.