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J Heesemann

Publications and source records attributed to J Heesemann.

At least 19 recordsLinked to original sources
PubMed2006

Prevalence of extended-spectrum beta-lactamases in isolates of the Enterobacter cloacae complex from German hospitals.

In 2002, 119 isolates of the Enterobacter cloacae complex were collected randomly from 11 German laboratories nationwide. Antibiotic susceptibilities were tested by disk-diffusion tests according to CLSI guidelines, and MICs were determined using Etests. PCRs were performed to amplify all TEM and SHV, and most CTX-M and OXA beta-lactamase genes. PCR products were sequenced to identify the precise extended spectrum beta-lactamase (ESBL) types. Isoelectric focusing (IEF) and PM/PML Etests were used to confirm production of the respective ESBLs. According to susceptibility tests and CLSI criteria, 49 (40%) isolates were resistant to extended-spectrum cephalosporins. Seven (5.8%) isolates were positive in at least one of the PCR assays. Sequencing identified production of TEM-1 beta-lactamase genes by three (2.9%) isolates, and ESBL genes of the CTX-M and SHV beta-lactamase families by five (4.2%) isolates. IEF confirmed the production of beta-lactamases in the expected pI ranges of the respective ESBLs, and four of the five ESBL-producers were detected using the PM/PML Etest. All ESBL-producing isolates showed co-resistance to sulphonamides.

Anti-Bacterial Agents↗
PubMed2005

[Bacterial infections following injections and infusion caused by errors of hygiene--how to avoid them].

Even minor medical interventions, such as injections, are associated with the risk of life-threatening infections--both in the doctor's office and hospital settings. Medical personnel in particular must always assume that they may be contaminated by facultative pathogenic, but potentially highly virulent, germs, although they themselves remain asymptomatic. Against this background, hygienic hand disinfection and proper skin disinfection are important hygiene measures for the prevention of infections, in particular in the case of invasive interventions. Strict attention must be paid to asepsis when preparing for injections and infusions. Sterile items must be protected against contamination. With regard to compliance with and application of hygiene standards, every physician must be an exemplary role model. Furthermore, all medical professional groups must receive appropriate training in hygiene management.

Cross Infection↗
PubMed2005

[Bacterial infections of the lungs in mucoviscidosis patients].

The pathogenesis of lung infections in patients with mucoviscidosis (cystic fibrosis, CF) is multifactorial. Both host- and pathogen-related factors are involved. The most important germ in terms of progression and pulmonary damage is Pseudomonas aeruginosa. However, the clinical relevance of other CF-typical pathogens has not yet been determined with certainty, and must be assessed on the basis of the clinical presentation of the individual case. To ensure optimal patient management, a CF-specific microbiological diagnostic work-up is mandatory. Since ever more patients now survive into adulthood, the problems associated with chronic infection are gaining in importance. In light of increasing multiresistance, the use of inhalation antibiotics, as well as combined antibiotic treatment, is becoming more and more determinative for the therapeutic outcome.

Administration, Inhalation↗
PubMed2005

Modulation of Rho GTPases and the actin cytoskeleton by YopT of Yersinia.

Pathogenic Yersinia species evade the innate cellular immune response by injecting antihost effector proteins (Yersinia outer proteins, Yops) into host cells through a type III secretion (TTS) apparatus. One of the six effector Yops, YopT, inactivates the small GTPase RhoA by removing the geranylgeranylated C-terminal cysteine. This cleavage results in release of RhoA from the cell membrane and subsequently in blockage of stress fiber formation. Thus YopT impairs cellular functions associated with cytoskeleton rearrangements.

Actins↗
PubMed2005

Asp f6, an Aspergillus allergen specifically recognized by IgE from patients with allergic bronchopulmonary aspergillosis, is differentially expressed during germination.

BACKGROUND: Aspergillus fumigatus is a pathogenic mould causing allergic and invasive respiratory diseases. Allergic bronchopulmonary Aspergillosis (ABPA) is a severe pulmonary complication resulting from hypersensitivity to A. fumigatus proteins. Aspergillus allergen Asp f6 is recognized by IgE from ABPA patients, but not from sensitized individuals, a fact that can be used to differentiate between these two groups of allergic patients. METHODS: Proteins from hyphae, resting and germinating conidia of A. fumigatus were compared by SDS-PAGE. Protein identification was performed using MALDI-TOF mass spectrometry. Recombinant A. fumigatus allergens were used to isolate specific monoclonal antibodies (mab) from a hybridoma bank generated against Aspergillus proteins. RESULTS: A hyphae-specific 23 kDa A. fumigatus protein was identified as the allergen Asp f6/manganese-dependent superoxide dismutase (MnSOD). Differential expression of MnSOD was confirmed by immunoblot using a specific mab. In contrast, Asp f8 another intracellular, but not ABPA-specific allergen, was detected in hyphae and conidia. CONCLUSIONS: Aspergillus fumigatus is able to colonize its environment by the formation of hyphae. Hyphae are found in the lung of ABPA patients, but not in patients suffering from atopic asthma. Our finding that Asp f6 is specifically expressed in hyphae might explain why an IgE response to Asp f6 is specific for ABPA patients.

Allergens↗
PubMed2004

Mixed lung infection by Legionella pneumophila and Legionella gormanii detected by fluorescent in situ hybridization.

A mixed infection by Legionella pneumophila and a nonpneumophila Legionella species was detected in a lung biopsy specimen obtained from a patient with atypical pneumonia by fluorescent in situ hybridization (FISH). This result was confirmed by polymerase chain reaction (PCR). Sequencing of PCR products confirmed mixed infection by L. pneumophila and L. gormanii. Culture for Legionella spp. was negative and serology showed a rise only in IgG anti- Legionella pneumophila titer. To our knowledge, this is the first report of a mixed infection by L. pneumophila and a non-pneumophila Legionella species detected by FISH. Because FISH is a rapid and culture independent method that detects specific microorganisms in biopsy specimens it is recommended, in particular, for the detection of fastidious bacteria.

Aged↗
PubMed2003

Characterization of a novel unique restriction-modification system from Yersinia enterocolitica O:8 1B.

Genetic manipulations with enteropathogenic Yersinia enterocolitica O:8 are complicated by the presence of an efficient PstI-like YenI restriction-modification (R-M) system. We have characterized the YenI R-M system in Y. enterocolitica O:8, biotype 1B. A 5039 bp DNA fragment of the pSAK2 recombinant plasmid carrying the yenI locus was used to determine the nucleotide sequence. DNA sequence analysis identified a single 2481 bp open reading frame (ORF) that encodes an 826 amino acid large polypeptide having an apparent molecular mass of 93 kDa. The N-terminal part of the YenI ORF has 45 and 40% identity to PstI and BsuI methyltransferases (MTases), respectively; while the C-terminal part depicts 55 and 45% identity to endonucleases (ENases) of both isoschyzomeric enzymes. The yenI gene was cloned into pT7-5 plasmid and has been shown to encode a single polypeptide of expected molecular mass. A specific recognition sequence, typical to the type II R-M systems and single peptide organization, typical to type IV R-M systems, make YenI unique among known restriction-modification systems. We have constructed a truncated recombinant variant of YenI enzyme, which conserved only MTase activity, and that can be applied to YenI methylation of the DNA to be transformed into Y. enterocolitica O:8 biotype 1B strains.

Base Sequence↗
PubMed2003

Toll-like receptor (TLR) 2 and TLR4 are essential for Aspergillus-induced activation of murine macrophages.

Aspergillus fumigatius is a ubiquitous saprophytic fungus that has become the most prevalent airborne fungal pathogen for immunocompromised patients during the last two decades. In this report we have analysed how macrophages recognize this microorganism. Using transfected human HEK 293 cells we demonstrate that NF-kappaB-dependent promoter activation triggered by A. fumigatus is mediated by Toll-like receptors TLR2 and TLR4, whereas no activation was observed in cells overexpressing other distinct TLR proteins (TLR1, TLR3, TLR5-10). Using macrophages derived from mice lacking TLR2 expression, expressing defective TLR4 or both we found that A. fumigatus conidia and hyphae induce NF-kappaB translocation, release of pro-inflammatory molecules, like TNFalpha, and the chemoattractant MIP-2 in a TLR2- and TLR4-dependent manner. Recognition of A. niger and A. fumigatus, was similar in terms of the parameters analysed, suggesting that pathogenic and non-pathogenic aspergilli are sensed by macrophages in a similar fashion. Finally, we found that recruitment of neutrophils is severely impaired in mice lacking both functional TLR2 and TLR4, but is less impaired in single TLR2- or TLR4-deficient mice, providing evidence that both receptors are required for an optimal immune response to Aspergillus in vivo.

Active Transport, Cell Nucleus↗
PubMed2003

Novel virulence-associated type II secretion system unique to high-pathogenicity Yersinia enterocolitica.

Yersinia enterocolitica strains comprise an important group of bacterial enteropathogens that cause a broad range of gastrointestinal syndromes. Three groups are distinguishable within this bacterial species, namely, the nonpathogenic group (biotype 1A strains), the low-pathogenicity, non-mouse-lethal group (biotypes 2 to 5), and the high-pathogenicity, mouse-lethal group (biotype 1B). To date, the presence of the high-pathogenicity island (HPI), a chromosomal locus that encodes the yersiniabactin system (involved in iron uptake), defines essentially the difference between low-pathogenicity and high-pathogenicity Y. enterocolitica strains, with the low-pathogenicity strains lacking the HPI. Using the powerful tool of representational difference analysis between the nonpathogenic 1A strain, NF-O, and its high-pathogenicity 1B counterpart, WA-314, we have identified a novel type II secretion gene cluster (yts1C-S) occurring exclusively in the high-pathogenicity group. The encoded secreton, designated Yts1 (for Yersinia type II secretion 1) was shown to be important for virulence in mice. A close examination of the almost completed genome sequence of another high-pathogenicity representative, Y. enterocolitica 8081, revealed a second putative type II secretion cluster uniformly distributed among all Y. enterocolitica isolates. This putative species-specific cluster (designated yts2) differed significantly from yts1, while resembling more closely the putative type II cluster present on the genome of Y. pestis. The Yts1 secreton thus appears to have been additionally acquired by the high-pathogenicity assemblage for a virulence-associated function.

Animals↗
PubMed2002

Representational difference analysis uncovers a novel IS10-like insertion element unique to pathogenic strains of Yersinia enterocolitica.

The method of suppressive subtractive hybridization was employed to map out genomic differences between the highly pathogenic Yersinia enterocolitica (Ye) biogroup 1B, serotype O:8 strain (WA-314) and the closely related apathogenic Y. enterocolitica biogroup 1A, serotype O:5 strain (NF-O). A novel IS10-like element, IS1330, uncovered by this technique was found to be uniquely present in high copy numbers among the highly pathogenic Y. enterocolitica 1B strains, while a single copy of the element was found in the low pathogenic Ye biogroup 4 serotype O:3 strain. The 1321-bp repetitive element has 19-bp imperfect inverted terminal repeats and is bracketed by a 10-bp duplication of the target sequence. The predicted transposase shares high homology with the IS10 open reading frame of the large virulence plasmid pWR501, of Shigella flexneri, with IS10 transposase of Salmonella typhi, and with IS1999 (tnpA) of Pseudomonas aeruginosa. The IS1330 tnp gene is transcribed in vitro and in vivo in HeLa cells. At least one copy of IS1330 flanks the recently described chromosomal type III secretion cluster in Y. enterocolitica WA-314, O:8, and future studies should shed light on whether this novel transposase mediates transposition events in highly pathogenic Y. enterocolitica strains, thus enhancing the genetic plasticity of this species.

Base Sequence↗
PubMed2002

[HYGEA (Hygiene in gastroenterology--endoscope reprocessing): Study on quality of reprocessing flexible endoscopes in hospitals and in the practice setting].

The quality of reprocessing gastroscopes, colonoscopes and duodenoscopes in daily routine of 25 endoscopy departments in hospitals and 30 doctors with their own practices was evaluated by microbiological testing in the HYGEA interventional study. In 2 test periods, endoscopes ready for use in patients were found contaminated at high rates (period 1: 49 % of 152 endoscopes; period 2: 39 % of 154 endoscopes). Culture of bacterial fecal flora (E. coli, coliform enterobacteriaceae, enterococci) was interpreted indicating failure of cleaning procedure and disinfection of endoscopes. Detection of Pseudomonas spp. (especially P. aeruginosa) and other non-fermenting rods - indicating microbially insufficient final rinsing and incomplete drying of the endoscope or a contaminated flushing equipment for the air/water-channel - pointed out endoscope recontamination during reprocessing or afterwards. Cause for complaint was found in more than 50 % of endoscopy facilities tested (period 2: 5 in hospitals, 25 practices). Reprocessing endoscopes in fully automatic chemo-thermally decontaminating washer-disinfectors with disinfection of final rinsing water led to much better results than manual or semi-automatic procedures (failure rate of endoscopy facilities in period 2 : 3 of 28 with fully automatic, 8 of 12 with manual, 9 of 15 with semi-automatic reprocessing). The study results give evidence for the following recommendations: 1. Manual brushing of all accessible endoscope channels has to be performed even before further automatic reprocessing; 2. For final endoscope rinsing, water or aqua dest. should only be used disinfected or sterile-filtered; 3. Endoscopes have to be dried thoroughly using compressed air prior to storage; 4. Bottle and tube for air/water-channel flushing have to be reprocessed daily by disinfection or sterilization, and in use, the bottle have to be filled exclusively with sterile water. The HYGEA study shows that microbiological testing of endoscopes is useful for detection of insufficient reprocessing and should be performed for quality assurance in doctors' practices, too. The study put recommendations for reprocessing procedures in more concrete terms.

Colony Count, Microbial↗
PubMed2001

Yersinia outer protein P of Yersinia enterocolitica simultaneously blocks the nuclear factor-kappa B pathway and exploits lipopolysaccharide signaling to trigger apoptosis in macrophages.

Exposure of macrophages to bacteria or LPS mediates activation of signaling pathways that induce expression of self defense-related genes. Pathogenic Yersinia species impair activation of transcription factor NF-kappaB and trigger apoptosis in macrophages. In this study, we dissected the mechanism of apoptosis induction by Yersinia. Selectively, Yersinia enterocolitica strains producing the effector protein Yersinia outer protein P (YopP) hampered NF-kappaB activation and subsequently conferred apoptosis to J774A.1 macrophages. Thereby, YopP bound and inhibited the macrophage NF-kappaB-activating kinase IKKbeta. YopP- and Yersinia-, but not Salmonella-induced apoptosis was specifically prevented by transient overexpression of NF-kappaB p65, giving evidence that YopP mediates cell death by disrupting the NF-kappaB signaling pathway. Transfection of J774A.1 macrophages with YopP induced a moderate, but significant degree of apoptosis (40-50% of transfected cells). This effect was strongly enhanced by additional initiation of LPS signaling (80-90%), indicating a synergism between LPS-induced signal transduction and inhibition of NF-kappaB by YopP. This reflects a strategy of a bacterial pathogen that takes advantage of LPS, serving as cofactor, to impair the macrophage.

Adhesins, Bacterial↗
PubMed2001

A ribonucleotide reductase homolog of cytomegalovirus and endothelial cell tropism.

Human cytomegalovirus infects vascular tissues and has been associated with atherogenesis and coronary restenosis. Although established laboratory strains of human cytomegalovirus have lost the ability to grow on vascular endothelial cells, laboratory strains of murine cytomegalovirus retain this ability. With the use of a forward-genetic procedure involving random transposon mutagenesis and rapid phenotypic screening, we identified a murine cytomegalovirus gene governing endothelial cell tropism. This gene, M45, shares sequence homology to ribonucleotide reductase genes. Endothelial cells infected with M45-mutant viruses rapidly undergo apoptosis, suggesting that a viral strategy to evade destruction by cellular apoptosis is indispensable for viral growth in endothelial cells.

3T3 Cells↗
PubMed2001

Integrative module of the high-pathogenicity island of Yersinia.

The high-pathogenicity island of Yersinia pestis (Yps HPI) encodes virulence-associated genes involved in siderophore yersiniabactin-mediated iron uptake. The Yps HPI contains a P4-type integrase (Int-HPI), associated with the asn-tRNA locus, and is flanked by 17 bp direct repeats. We constructed a minimal integrative module of the pathogenicity island carrying the reconstituted 266 bp attP (POP') attachment site derived from putative attR and attL junctions of the Yps HPI and the functional int-HPI gene from Y. pestis KUMA. The attP-int-HPI module recombined efficiently, site specifically and RecA independently with the bacterial attB site present either in the chromosome (asn-tDNA) or on a plasmid, with no preference for a certain asn-tRNA gene. The excision of the integrated suicide plasmid carrying the integrative module, on the other hand, was a rare event and could be demonstrated only by polymerase chain reaction. Analysis of the 5' terminus of the transcript for int-HPI revealed that the integration of attP-int-HPI was coupled with the replacement of the endogenous int-HPI promoter, localized in the P' part of the attP site, by the adjacent asn-tRNA promoter. These results suggest that two alternative promoters control integration and excision of the HPI by its integrase.

Attachment Sites, Microbiological↗
PubMed2001

YopE of Yersinia, a GAP for Rho GTPases, selectively modulates Rac-dependent actin structures in endothelial cells.

Yersinia spp. inject effector proteins (Yersinia outer proteins, Yops) into target cells via a type III secretion apparatus. The effector YopE was recently shown to possess GAP activity towards the Rho GTPases RhoA, Rac and CDC42 in vitro. To investigate the intracellular, 'in vivo' targets of YopE we generated a Yersinia enterocolitica strain [WA(pYLCR+E)] that injects 'life-like' amounts of YopE as only effector. Primary human umbilical vein endothelial cells (HUVEC) were infected with WA(pYLCR+E) and were then stimulated with: (i) bradykinin to induce actin microspikes followed by ruffles as an assay for CDC42 activity followed by CDC42 stimulated Rac activity; (ii) sphingosine-1-phosphate to form ruffles by direct Rac activation; or (iii) thrombin to generate actin stress fibres through Rho activation. In WA(pYLCR+E)-infected HUVEC microspike formation stimulated with bradykinin remained intact but the subsequent development of ruffles was abolished. Furthermore, ruffle formation after stimulation with sphingosine-1-phosphate or thrombin induced production of stress fibres was unaltered in the infected cells. These data suggest that YopE is able to inhibit Rac- but not Rho- or CDC42-regulated actin structures and, more specifically, that YopE is capable of blocking CDC42Hs dependent Rac activation but not direct Rac activation in HUVEC. This provides evidence for a considerable specificity of YopE towards selective Rac-mediated signalling pathways in primary target cells of Yersinia.

Actins↗
PubMed2001

Modulation of Rho GTPases and the actin cytoskeleton by Yersinia outer proteins (Yops).

Pathogenic species of the genus Yersinia employ a type III secretion apparatus to inject up to six effector proteins (Yersinia outer proteins; Yops) into host cells. Thereby yersiniae disarm the immune cell system of the host to proliferate extracellularly. At least four of the Yop effectors (YopE, YpkA/YopO, YopT and YopH) are involved in the rearrangement of the actin cytoskeleton: YopE, YopT and YpkA/YopO modulate the activity of actin-regulating Rho GTP-binding proteins, whereas YopH dephosphorylates phospho-tyrosine residues in focal adhesion proteins. In this review we will focus on recent evidence implicating Rho GTPases and the actin cytoskeleton as major targets of Yersinia Yops.

Actins↗