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1.  In vivo detection of mucosal healing-involved histiocytes by confocal laser endomicroscopy 
Histiocytes have a pivotal role in wound repair and intestinal epithelial recovery - the most important goal to sustain gut functionality. Yet, an in vivo description of colonic histiocytes by confocal laser endomicroscopy (CLE) is missing. Here, we report the case of a 45-years-old male patient who was referred to our clinic with weight loss and a history of two consecutive Clostridium difficile colitis episodes, the latter cured 3 wk before present admission. Stool microbiology was negative. Conventional colonoscopy showed atrophy and a light mucosal oedema in the distal colon. During on-going endoscopy, we performed a fluorescein-aided CLE which revealed large polygonal (histiocytes-like) cells with copious cytoplasm and large nuclei in the lamina propria of the sigmoid colon as well as regenerative epithelial changes. Histopathological assessment of biopsies from the same areas confirmed the endomicroscopical findings: Periodic acid-Schiff- and CD68-positive foamy histiocytes in the colonic lamina propria and an advanced epithelial recovery. Since stool microbiology was repeatedly negative and polymerase chain reaction-analysis from colonic biopsies could not detect any mRNA for Thropheryma whippleii and common pathogens, we interpreted this particular setting as a mucosal healing process after consecutive Clostridium difficile infections. In conclusion, by describing these colonic histiocytes, we highlight the clinical usefulness of CLE in describing the entity of histiocytes in vivo and in real-time during the process of post-infectious mucosal healing in the colon.
PMCID: PMC3436064  PMID: 22969212
Endomicroscopy; Mucosal healing; Advanced colonic imaging; Colonic histiocytes
2.  High Frequency of Tropheryma whipplei in Culture-Negative Endocarditis 
Journal of Clinical Microbiology  2012;50(2):216-222.
“Classical” Whipple's disease (cWD) is caused by Tropheryma whipplei and is characterized by arthropathy, weight loss, and diarrhea. T. whipplei infectious endocarditis (TWIE) is rarely reported, either in the context of cWD or as isolated TWIE without signs of systemic infection. The frequency of TWIE is unknown, and systematic studies are lacking. Here, we performed an observational cohort study on the incidence of T. whipplei infection in explanted heart valves in two German university centers. Cardiac valves from 1,135 patients were analyzed for bacterial infection using conventional culture techniques, PCR amplification of the bacterial 16S rRNA gene, and subsequent sequencing. T. whipplei-positive heart valves were confirmed by specific PCR, fluorescence in situ hybridization, immunohistochemistry, histological examination, and culture for T. whipplei. Bacterial endocarditis was diagnosed in 255 patients, with streptococci, staphylococci, and enterococci being the main pathogens. T. whipplei was the fourth most frequent pathogen, found in 16 (6.3%) cases, and clearly outnumbered Bartonella quintana, Coxiella burnetii, and members of the HACEK group (Haemophilus species, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella kingae). In this cohort, T. whipplei was the most commonly found pathogen associated with culture-negative infective endocarditis.
PMCID: PMC3264169  PMID: 22135251
3.  Detection of “Candidatus Neoehrlichia mikurensis” in Two Patients with Severe Febrile Illnesses: Evidence for a European Sequence Variant▿  
Journal of Clinical Microbiology  2010;48(7):2630-2635.
Recently, a new genus of Anaplasmataceae termed “Candidatus Neoehrlichia” was discovered in ticks and rodents. Here, we report on two patients who suffered from febrile bacteremia due to “Candidatus Neoehrlichia mikurensis” associated with thrombotic or hemorrhagic events. 16S rRNA and groEL gene sequencing provided evidence of three groups of sequence variants.
PMCID: PMC2897504  PMID: 20519481
4.  Acute syphilitic chorioretinitis after a missed primary diagnosis: a case report 
Syphilis is well known as an infectious disease which can present with a large variety of symptoms. Clinical diagnosis can be difficult and may be complicated in modern medicine by immunosuppressive treatment and possible side effects of medication.
Case presentation
We describe a rare case of placoid chorioretinitis due to Treponema pallidum which developed after the primary symptom of proteinuria was not recognized as a rare manifestation of syphilis. Diagnosis of syphilitic chorioretinitis and/or endophthalmitis was made by broad range amplification of the bacterial 16S ribosomal RNA gene obtained from vitreous after diagnostic vitrectomy.
This case shows that clinicians should be alert in patients with proteinuria and chorioretinitis as they can represent rare manifestations of syphilis. Syphilis should be in the differential diagnosis of any unknown symptom and in the presumed side effects of medication.
PMCID: PMC2248591  PMID: 18241329
5.  Fatal Bioprosthetic Aortic Valve Endocarditis Due to Cardiobacterium valvarum▿  
Journal of Clinical Microbiology  2007;45(7):2324-2326.
Cardiobacterium valvarum was isolated from the blood of a 71-year-old man with fatal aortic valve endocarditis. The API NH system was used for phenotypic characterization of the C. valvarum strain. This is the first case of infective endocarditis caused by C. valvarum in Germany and the first case worldwide affecting a prosthetic valve and lacking an obvious dental focus.
PMCID: PMC1933016  PMID: 17475754
6.  Osteomyelitis of the Ulna Caused by Porphyromonas gingivalis 
Journal of Clinical Microbiology  2006;44(10):3835-3837.
A 41-year-old man was provided with a jacket crown after a root end resection of a molar. Four months later, cortical destruction of the ulnar diaphysis with swelling and pain appeared in his forearm. No microorganism could be grown from an intraoperative tissue specimen, but bacterial 16S rRNA genes were detected by broad-range PCR, revealing Porphyromonas gingivalis as the causative agent of osteomyelitis.
PMCID: PMC1594789  PMID: 17021123
7.  High Diversity of ankA Sequences of Anaplasma phagocytophilum among Ixodes ricinus Ticks in Germany 
Journal of Clinical Microbiology  2003;41(11):5033-5040.
In Germany humans with acute granulocytic ehrlichiosis have not yet been described. Here, we characterized three different genes of Anaplasma phagocytophilum strains infecting German Ixodes ricinus ticks in order to test whether they differ from strains in other European countries and the United States. A total of 1,022 I. ricinus ticks were investigated for infection with A. phagocytophilum by nested PCR and sequence analysis. Forty-two (4.1%) ticks were infected. For all positive ticks, parts of the 16S rRNA and groESL genes were sequenced. The complete coding sequence of the ankA gene could be determined in 24 samples. The 16S rRNA and groESL gene sequences were as much as 100% identical to known sequences. Fifteen ankA sequences were ≥99.37% identical to sequences derived from humans with granulocytic ehrlichiosis in Europe and from a horse with granulocytic ehrlichiosis in Germany. Thus, German I. ricinus ticks most likely harbor A. phagocytophilum strains that can cause disease in humans. Nine additional sequences were clearly different from known ankA sequences. Because these newly described sequences have never been obtained from diseased humans or animals, their biological significance is currently unknown. Based on this unexpected sequence heterogeneity, we propose to use the ankA gene for further phylogenetic analyses of A. phagocytophilum and to investigate the biology and pathogenicity of strains that differ in the ankA gene.
PMCID: PMC262509  PMID: 14605135
8.  Tuboovarian Abscess Caused by Atopobium vaginae following Transvaginal Oocyte Recovery 
Journal of Clinical Microbiology  2003;41(6):2788-2790.
A 39-year-old woman with tubarian sterility fell ill with acute pelvic inflammatory disease 2 months after transvaginal oocyte recovery. Laparotomy revealed a large tuboovarian abscess, from which Atopobium vaginae, an anaerobic gram-positive coccoid bacterium of hitherto unknown clinical significance, was isolated. The microbial etiology and the risk of pelvic infections following transvaginal punctures are discussed.
PMCID: PMC156532  PMID: 12791933
9.  Polyphosphate Kinase of Acinetobacter sp. Strain ADP1: Purification and Characterization of the Enzyme and Its Role during Changes in Extracellular Phosphate Levels 
Polyphosphate (polyP) is a ubiquitous biopolymer whose function and metabolism are incompletely understood. The polyphosphate kinase (PPK) of Acinetobacter sp. strain ADP1, an organism that accumulates large amounts of polyP, was purified to homogeneity and characterized. This enzyme, which adds the terminal phosphate from ATP to a growing chain of polyP, is a 79-kDa monomer. PPK is sensitive to magnesium concentrations, and optimum activity occurs in the presence of 3 mM MgCl2. The optimum pH was between pH 7 and 8, and significant reductions in activity occurred at lower pH values. The greatest activity occurred at 40°C. The half-saturation ATP concentration for PPK was 1 mM, and the maximum PPK activity was 28 nmol of polyP monomers per μg of protein per min. PPK was the primary, although not the sole, enzyme responsible for the production of polyP in Acinetobacter sp. strain ADP1. Under low-phosphate (Pi) conditions, despite strong induction of the ppk gene, there was a decline in net polyP synthesis activity and there were near-zero levels of polyP in Acinetobacter sp. strain ADP1. Once excess phosphate was added to the Pi-starved culture, both the polyP synthesis activity and the levels of polyP rose sharply. Increases in polyP-degrading activity, which appeared to be mainly due to a polyphosphatase and not to PPK working in reverse, were detected in cultures grown under low-Pi conditions. This activity declined when phosphate was added.
PMCID: PMC99700  PMID: 10473375
10.  The Genes rubA and rubB for Alkane Degradation in Acinetobacter sp. Strain ADP1 Are in an Operon with estB, Encoding an Esterase, and oxyR 
Journal of Bacteriology  1999;181(14):4292-4298.
Alkanes are oxidized in Acinetobacter sp. strain ADP1 by a three-component alkane monooxygenase, composed of alkane hydroxylase, rubredoxin, and rubredoxin reductase. rubA and rubB encode rubredoxin and a NAD(P)H-dependent rubredoxin reductase. We demonstrate here that single base pair substitutions in rubA or rubB lead to defects in alkane degradation, showing that both genes are essential for alkane utilization. Differences in the degradation capacity for hexadecane and dodecane in these mutants are discussed. Two genes, estB and oxyR, are located downstream of rubB, but are not necessary for alkane degradation. estB encodes a functional esterase. oxyR encodes a LysR-type transcriptional regulator, conferring resistance to hydrogen peroxide. rubA, rubB, estB, and oxyR constitute an operon, which is constitutively transcribed from a ς70 promoter, and an estB-oxyR containing message is also transcribed from an internal promoter.
PMCID: PMC93931  PMID: 10400587
11.  Expression of Alkane Hydroxylase from Acinetobacter sp. Strain ADP1 Is Induced by a Broad Range of n-Alkanes and Requires the Transcriptional Activator AlkR 
Journal of Bacteriology  1998;180(22):5822-5827.
In Acinetobacter sp. strain ADP1, alkane degradation depends on at least five essential genes. rubAB and xcpR are constitutively transcribed. Here we describe inducible transcription of alkM, which strictly depends on the presence of the transcriptional activator AlkR. alkR itself is expressed at a low level, while a chromosomally located alkM::lacZ fusion is inducible by middle-chain-length alkanes from heptane to undecane, which do not support growth of ADP1, and by long-chain-length alkanes from dodecane to octadecane, which are used as sources of carbon and energy. The putative AlkM substrate 1-dodecene is also an effective inducer. Products of alkane hydroxylase activity like 1-dodecanol prevent induction of alkM expression. alkM is expressed only in stationary phase, suggesting its dependence on at least one other regulatory mechanism.
PMCID: PMC107653  PMID: 9811637
12.  Alkane Hydroxylase from Acinetobacter sp. Strain ADP1 Is Encoded by alkM and Belongs to a New Family of Bacterial Integral-Membrane Hydrocarbon Hydroxylases 
Degradation of long-chain alkanes by Acinetobacter sp. strain ADP1 involves rubredoxin and rubredoxin reductase. We complemented a mutant deficient in alkane utilization and sequenced four open reading frames (ORFs) on the complementing DNA. Each of these ORFs was disrupted by insertional mutagenesis on the chromosome. As determined from sequence comparisons, ORF1 and ORF4 seem to encode a rotamase of the PpiC type and an acyl coenzyme A dehydrogenase, respectively. Disruption of these ORFs does not affect alkane utilization. In contrast, the two other ORFs, alkR and alkM, are essential for growth on alkanes as sole carbon sources. alkR encodes a polypeptide with extensive homology to AraC-XylS-like transcriptional regulators. It is located next to alkM, which encodes the terminal alkane hydroxylase, but is in the opposite orientation. Sequence homologies with other bacterial integral-membrane hydrocarbon hydroxylases suggest that AlkM may be the first member of a new protein family. The genes identified here are not linked to the rubredoxin- and rubredoxin reductase-encoding genes on the Acinetobacter sp. strain ADP1 chromosome.
PMCID: PMC106126  PMID: 9546151
13.  Transcription of ppk from Acinetobacter sp. Strain ADP1, Encoding a Putative Polyphosphate Kinase, Is Induced by Phosphate Starvation 
Polyphosphate kinase (Ppk) catalyzes the formation of polyphosphate from ATP. We cloned the ppk gene (2,073 bp) from Acinetobacter sp. strain ADP1; this gene encodes a putative polypeptide of 78.6 kDa with extensive homology to polyphosphate kinase from Escherichia coli and other bacteria. Chromosomal disruption of ppk by inserting a transcriptionally fused lacZ does not affect growth under conditions of phosphate limitation or excess. β-Galactosidase activity expressed from the single-copy ppk::lacZ fusion is induced 5- to 15-fold by phosphate starvation. An increased amount of ppk transcript (2.2 kb) was detected when cells were grown at a limiting phosphate concentration. Primer extension analysis revealed a regulated promoter located upstream of a second, constitutive promoter. Potential similarities of this regulation with the effects of PhoB and PhoR of E. coli are discussed.
PMCID: PMC106343  PMID: 9501429

Results 1-13 (13)