PubMed Health⌕ Search

Biomedical subjects

A Podbielski

Publications and source records attributed to A Podbielski.

At least 19 recordsLinked to original sources
PubMed2006

[Postoperative infection of an epigastric hematoma caused by Aeromonas veronii biovar sobria].

HISTORY: A 52-year-old man with a gastric signet-ring cell carcinoma but without acute symptoms was admitted for reconstructive surgery of the gastrointestinal tract. INVESTIGATIONS: Before the present surgery all functional and radiological tests merely confirmed the previously known disease. Except for mild anemia and abnormal electrolytes all laboratory tests were within normal limits. COURSE, DIAGNOSIS AND TREATMENT: The patient underwent reconstructive surgery of the gastrointestinal tract, namely an ascending sigmoidostomy and resection of an enterocutaneous fistula. For a few days the postoperative development was as expected and the drain, placed during surgery, was removed at the expected time. 9 days postoperatively the patient developed signs of an infection (fever up to 38.8 degrees C, increased WBC and raised C-reactive protein levels). Computed tomography (CT) of the abdomen revealed an epigastric tumor measuring 6 x 5 cm. CT-guided needle aspiration of this lesion showed macroscopic signs of an infected hematoma. A pigtail catheter was successfully implanted for continuous drainage. Both the fluids obtained from CT-guided aspiration and the pigtail drain grew Aeromonas veronii biovar sobria when cultured on standard blood agar. Administration of both cefotaxim and metronidazole for 10 days produced a decrease in the inflammatory parameters. The abdominal CT at that time showed a noticeable regression of the epigastric mass so that the patient was discharged from hospital 3 weeks after surgery. CONCLUSION: This case emphasizes the importance of adequately dosed antibiotic therapy, also for unusual bacteria such as species of Aeromonas.

Aeromonas↗
PubMed2006

[Toxic-shock-like-syndrome caused by beta-hemolysing group G streptococci in a multimorbid patient with erysipelas].

HISTORY AND FINDINGS: A 41-year-old, obese man with a history of incomplete paraplegia of both legs and chronic venous insufficiency with stasis dermatitis presented with acute respiratory and hyperdynamic hemodynamic failure. He was transferred from another hospital to the department of intensive care medicine for further diagnosis and treatment. A livid coloured, necrotizing-hemorrhagic swelling of the right lower leg was noted. INVESTIGATIONS: Laboratory tests revealed an inflammation probably due to bacterial infection, anemia, acute renal failure, acute hepatic dysfunction, coagulopathy and lactic acidosis, indicating multi-organ failure and septic shock. No focus of sepsis was found at abdominal sonography and exploratory laparotomy. Chest X-Ray and computed tomography revealed bilateral pneumonia. Doppler ultrasonography of both legs showed acute isolated thrombosis of the right posterior tibial vein. TREATMENT AND COURSE: In addition to a chronic venous ulcer-necrotizing hemorrhagic erysipelas had developed in the right lower leg. A swab taken at surgery and blood cultures grew Streptococcus dysgalactiae ssp. equisimilis (group G streptococci, GGS). Despite intensive care treatment and high dosage penicillin G therapy the patient died two days after admission from septic shock and multi-organ failure. CONCLUSIONS: Group G streptococci cause a variety of common and severe infections. Erysipelas is infrequently associated with GGS but, much more often, with group A streptococci (GAS). This unusual and fulminant case emphasizes the importance of considering Streptococcus dysgalactiae as a causative agent in septicemia with multiple predisposing factors and soft-tissue infections.

Adult↗
PubMed2005

[Listeria endophthalmitis].

Listeria monocytogenes is a rare cause of endogenous endophthalmitis. During the last 20 years about 30 cases have been published, all of which showed similar clinical features and a profound visual loss mainly owing to delayed diagnosis. This case report is about an otherwise healthy 41-year-old woman whose diagnosis was established 17 days after the onset of symptoms by microbiological cultures. Under sufficient therapy signs of local inflammation disappeared and intraocular pressure decreased. Pars plana vitrectomy was necessary; although post-surgery complications developed, the result was complete recovery of visual acuity.

Adult↗
PubMed2004

[Experience with the Platelia Candida ELISA for the diagnostics of invasive candidosis in neutropenic patients].

Invasive Candida infections (IC) belong to the most important opportunistic fungal infections in immunocompromised patients. IC is difficult to diagnose, because clinical symptoms are nonspecific and cultural methods lack sensitivity or specificity. We evaluated the Platelia Candida enzyme immunoassay (Candida EIA) for the diagnosis of IC in patients with haematological malignancies. A total of 62 neutropenic patients with 469 serum samples were included in the study. Candida colonization was monitored by weekly cultures of mouth washings, urine, and stool samples. Yeasts were grown from samples of 42 patients (68%), mainly Candida albicans (50%), followed by Candida glabrata (23%) and Candida krusei (20%). According to the criteria of the EORTC/NIH, the patients were categorized: (1) 3 patients with proven IC; (2) 6 patients with probable IC; (3) 34 patients colonized with Candida; (4) 19 patients without Candida colonization and without IC. In the patient categories (1) to (4), 3/3 (100%), 3/6 (50%), 20/34 (59%), and 7/19 (37%) patients were Candida EIA positive (>0.5 ng/ml) in at least one serum sample. The sensitivity of the assay for the detection of proven IC was 100%, for proven and probable IC 67%, the specificity was 49% for both groups. An increase of the cut-off value to 2.0 ng/ml raised the specificity to 61%, but lowered the sensitivity to 56%. In conclusion, the Platelia Candida EIA does not discriminate between Candida colonization and probable invasive infection in haematological patients.

Antigens, Fungal↗
PubMed2001

Similarities between complement-mediated and streptolysin S-mediated hemolysis.

The oxygen-stable hemolysin streptolysin S (SLS) of Streptococcus pyogenes is encoded in part by the pel/sagA gene product. Antibodies to a synthetic peptide from the C terminus of the Pel/SagA open reading frame inhibited hemolysis mediated by both culture supernatants from multiple M serotypes of S. pyogenes isolates or a commercially available SLS preparation. Analysis of the SLS-mediated hemolytic reaction demonstrated that it was temperature- and concentration-dependent. Like complement-mediated hemolysis it conforms to the prediction of a one-hit mechanism of hemolysis. A number of intermediates in the SLS-mediated hemolysis of sheep erythrocytes could be distinguished. SLS could bind to erythrocytes below 17 degrees C; however, lysis could only occur at temperatures >23 degrees C. Following binding of SLS and washing, a papain-sensitive intermediate could be distinguished prior to insertion of the SLS complex into the erythrocyte membrane, which resulted in formation of a transmembrane pore and led to irreversible osmotic lysis of the cell. These intermediates were similar to those described previously during complement-mediated hemolysis.

Animals↗
PubMed2001

Group A streptococcal growth phase-associated virulence factor regulation by a novel operon (Fas) with homologies to two-component-type regulators requires a small RNA molecule.

A novel growth phase-associated two-component-type regulator, Fas (fibronectin/fibrinogen binding/haemolytic activity/streptokinase regulator), of Streptococcus pyogenes was identified in the M1 genome sequence, based on homologies to the histidine protein kinase (HPK) and response regulator (RR) part of the Staphylococcus aureus Agr and Streptococcus pneumoniae Com quorum-sensing systems. The fas operon, present in all 12 tested M serotypes, was transcribed as polycystronic message (fasBCA) and contained genes encoding two potential HPKs (FasB and FasC) and one RR (FasA). Downstream of fasBCA, we identified a small 300 nucleotide monocistronic transcript, designated fasX, that did not appear to encode true peptide sequences. Measurements of luciferase promoter fusions revealed a growth phase-associated transcription of fasBCA and fasX, with peak activities during the late exponential phase. Insertional mutagenesis disrupting fasBCA and fasA led to a phenotype similar to agr-null mutations in S. aureus, with prolonged expression of extracellular matrix protein-binding adhesins and reduced expression of secreted virulence factors such as streptokinase and streptolysin S. In addition, fasX transcription was dependent on the RR FasA; however, deletion mutagenesis of fasX resulted in a similar phenotype to that of the fasBCA or fasA mutants. Complementation of the fasX deletion mutant, with the fasX gene expressed in trans from a plasmid, restored the wild-type fasBCA regulation pattern. This strongly suggested that fasX, a putative non-translated RNA, is the main effector molecule of the fas regulon. However, using spent culture supernatants from wild-type and fas mutant strains, we were not able to show an influence on the logarithmic growth phase expression of fas and dependent genes. Thus, despite structural and functional similarities between fas and agr, to date the fas operon appears not to be involved in group A streptococcal (GAS) quorum-sensing regulation.

Amino Acid Sequence↗
PubMed2001

The SpeB virulence factor of Streptococcus pyogenes, a multifunctional secreted and cell surface molecule with strepadhesin, laminin-binding and cysteine protease activity.

The interactions between pathogenic bacteria and the host need to be resolved at the molecular level in order to develop novel vaccines and drugs. We have previously identified strepadhesin, a novel glycoprotein-binding activity in Streptococcus pyogenes, which is regulated by Mga, a regulator of streptococcal virulence factors. We have now identified the protein responsible for the strepadhesin activity and find that (i) strepadhesin activity is carried by SpeB, streptococcal pyrogenic exotoxin with cysteine protease activity; (ii) SpeB carries laminin-binding activity of the bacteria; and (iii) SpeB is not only a secreted molecule but also occurs unexpectedly tightly bound to the bacterial cell surface. Thus, in contrast to the previous view of SpeB as mainly an extracellular protease, it is also present as a streptococcal surface molecule with binding activity to laminin and other glycoproteins.

Adhesins, Bacterial↗
PubMed2001

The role played by the group A streptococcal negative regulator Nra on bacterial interactions with epithelial cells.

Group A streptococci (GAS) specifically attach to and internalize into human epithelial host cells. In some GAS isolates, fibronectin-binding proteins were identified as being responsible for these virulence traits. In the present study, the previously identified global negative regulator Nra was shown to control the binding of soluble fibronectin probably via regulation of protein F2 and/or SfbII expression in the serotype M49 strain 591. According to results from a conventional invasion assay based on the recovery of viable intracellular bacteria, the increased fibronectin binding did not affect bacterial adherence to HEp-2 epithelial cells, but was associated with a reduction in the internalization rates. However, when examined by confocal and electron microscopy techniques, the nra-mutant bacteria were shown to exhibit higher adherence and internalization rates than the corresponding wild type. The mutant bacteria escaped from the phagocytic vacuoles much faster, promoting consistent morphological changes which resulted in severe host cell damage. The apoptotic and lytic processes observed in nra-mutant infected host cells were correlated with an increased expression of the genes encoding superantigen SpeA, the cysteine protease SpeB, and streptolysin S in the nra-mutant bacteria. Adherence and internalization rates of a nra/speB-double mutant at wild-type levels indicated that the altered speB expression in the nra mutant contributed to the observed changes in both processes. The Nra-dependent effects on bacterial virulence were confined to infections carried out with stationary growth phase bacteria. In conclusion, the obtained results demonstrated that the global GAS regulator Nra modulates virulence genes, which are involved in host cell damage. Thus, by helping to achieve a critical balance of virulence factor expression that avoids the injury of target cells, Nra may facilitate GAS persistence in a safe intracellular niche.

Bacterial Adhesion↗
PubMed2001

Horizontal gene transfer and host specificity of beta-haemolytic streptococci: the role of a putative composite transposon containing scpB and lmb.

Beta-haemolytic streptococci are important human and animal pathogens: their genetic traits that are associated with the ability to infect human hosts remain, however, unclear. The surface protein, Lmb, mediates the adherence of Streptococcus agalactiae to human laminin. For further analysis of the corresponding gene, the adjacent genomic regions were sequenced. Lmb is localized on a putative composite transposon of 16 kb and is flanked by two copies of a novel insertion sequence element (ISSag2). It harbours the genes scpB and lmb, which are 98% identical with the respective genes of Streptococcus pyogenes. Analysis of the distribution of these genes and ISSag2 among 131 streptococcal strains revealed that all of the human isolates, but only 20% (12 of 61) of the animal isolates, contained scpB and lmb or their homologues. To investigate if the putative transposon can be mobilized, an erythromycin resistance marker was incorporated into the lmb gene of S. agalactiae. Screening for mutant strains with a regained susceptibility for erythromycin identified strains with a deletion of scpB, lmb, and one copy of ISSag2. We hypothesize that a horizontal gene transfer caused the exchange of scpB and lmb and that the ability of S. pyogenes, S. agalactiae and group C and G streptococcal strains to colonize or infect human hosts is dependent on their presence.

Adhesins, Bacterial↗
PubMed2001

Use of human preconditioned phagocytes for extracorporeal immune support: introduction of a concept.

Neutrophils are critical effector cells in humoral and innate immunity and play a vital role in phagocytosis and bacterial killing. If they and/or their specific functions are lacking, then immunoparalysis may occur, and severe diseases like systemic inflammatory response syndrome (SIRS) or sepsis can take a fatal course. In this paper, we discuss the possibility of using preconditioned cells in an extracorporeal biohybrid immune support system. A human promyelocytic cell line was stimulated for different times with all-trans retinoic acid. The resulting cells displayed major signs and functions of mature neutrophilic granulocytes including oxygen radical production, phagocytosis of living and dead Escherichia coli, Staphylococcus aureus, Candida albicans, intracellular killing, and interleukin production. The cells can be expanded to yield a sufficient cell mass, and subsequent prestimulation results in an expression of specific neutrophil functions. Extracorporeal bioreactor experiments seem to be feasible to test the benefit in immunoparalysis-associated diseases like SIRS or sepsis.

Bioreactors↗
PubMed2001

Virulence of group A streptococci in fertile hens eggs is mainly effected by M protein and streptolysin O.

In this study we have investigated whether streptolysin O contributes to the virulence of group A streptococci. For this purpose we generated M-negative and SLO-negative mutants by insertion mutagenesis into the chromosome of an M type 1 strain. The inactivation of M1 protein expression was achieved by the construction of the integrative plasmid pSFABS, which contains the internal fragment abs of the emm1 gene. Integration of pSFABS by homologous recombination into the chromosome of strain 38 541 resulted in the generation of mutant EMM1. Inactivation of slo with plasmid pFWSLOD resulted in two different mutant forms. The homologous recombination with plasmid pFWSLOD carrying the two slo fragments slo1 (899 base pairs in the 5' region) and slo2 (709 base pairs in the downstream part) resulted in mutants SLO3, SLO4 and SLO17. In SLO17 a double crossover event took place with insertion of the spectinomycin resistance gene aad9 between the slo fragments 1 and 2. In mutants SLO3 and SLO4 the homologous recombination with the same plasmid led to the integration of the whole plasmid construct into the chromosome of strain 38 541. Both forms of mutation failed to express SLO. In mutant SLO4 additionally M1 protein expression was significantly decreased. The mutants EMM1 (M-, SLO+) and SLO4 (M decreased, SLO-) showed a reduced binding to collagen-coated surfaces. In contrast the mutants SLO3 and SLO17 (both M+, SLO-) and the wild-type strain 38 541 (M+, SLO+) showed an affinity to collagen similar to purified M1 protein. All mutants were less virulent for chicken embryos compared to the wild-type strain after infection by intravenous injection as well as by application onto the chorioallantoic membrane. The results show that besides M protein SLO can also influence virulence of group A streptococci. Moreover, it became obvious that streptococci need more than one tool to fully develop their infectious potential.

Animals↗
PubMed2001

Group A streptococcal rofA gene is involved in the control of several virulence genes and eukaryotic cell attachment and internalization.

The serotype M6 group A streptococcal RofA regulator was previously shown to exert a direct positive control of protein F1 expression and, concomitantly, fibronectin binding. Using a serotype M6 rofA mutant, we demonstrate here that this regulator has a potentially indirect negative influence on the expression of the mga, emm6, pel-sagA, and speA virulence genes. Additionally, the rofA mutant exhibited reduced eukaryotic cell internalization rates in combination with decreased host cell viability.

Bacterial Adhesion↗
PubMed2000

Inactivation of the cysteine protease SpeB affects hyaluronic acid capsule expression in group A streptococci.

The human pathogen Streptococcus pyogenes expresses several virulence factors that are required for the pathogens survival within the host and the concomitant development of disease. To examine the influence of one virulence factor, the extracellular cysteine protease SpeB, on the expression of other virulence factors, the speB structural gene of a serotype M3 and M49 strain was inactivated. Morphologic examination, quantification of extracellular hyaluronic acid capsule, and Northern blot analysis of the isogenic speB -mutants revealed a strain-dependent decrease of hyaluronic acid capsule production and an increase in superoxide dismutase transcription. The transcription of streptolysin O (slo), di- and oligo-peptide permease (dpp, opp), hyaluronidase (hyl), streptokinase (ska) and streptococcal pyrogenic exotoxin A (speA) was unaffected.

Bacterial Capsules↗
PubMed2000

Growth inhibitory activity of gutta-percha points containing root canal medications on common endodontic bacterial pathogens as determined by an optimized quantitative in vitro assay.

Gutta-percha points containing calcium hydroxide, zinc oxide (ZnO), a mixture of ZnO and chlorhexidine (ZnO/CHX), iodine-polyvinylpyrrolidone (ZnO/J-PVP), or a mixture of CHX and J-PVP and ZnO (ZnO/CHX/J-PVP) were tested for their ability to inhibit growth of pure cultures of bacterial species commonly involved in endodontic infections (Peptostreptococcus micros, Streptococcus intermedius, Enterococcus faecalis, and Porphyromonas gingivalis). To quantitate growth inhibition, an in vitro assay was established that controlled for important parameters of root canal infection. Approximately 10(7) bacteria per assay were suspended in diluted human serum and co-incubated with the gutta-percha points in an anaerobic atmosphere for up to 2 wk. Aliquots used for determination of colony counts were taken on days 0, 1, 2, 4, 7, and 14 of incubation. As judged by colony-forming unit reduction kinetics and final counts, calcium hydroxide had better growth inhibitory activity than ZnO/CHX, ZnO/J-PVP, and ZnO alone for all bacteria tested except Peptostreptococcus micros. The combination of CHX and J-PVP with ZnO did not render results different from those of ZnO/CHX or ZnO/J-PVP. The results of this study support the introduction of standardized assays for testing antibacterial properties of root canal medications under conditions that more closely resemble those encountered in endodontal infections.

Anti-Infective Agents, Local↗
PubMed2000

Role of group A streptococcal virulence factors in adherence to keratinocytes.

To evaluate the role of putative group A streptococcal virulence factors in the initiation of skin infections, we compared the adherence of a wild-type M49-protein skin-associated strain to that of a series of 16 isogenic mutants created by insertional inactivation of virulence genes. None of the mutants, including the M-protein-deficient (emm mutant) strain, displayed reduced adherence to early-passage cultured human keratinocytes, but adherence of the mutant lacking hyaluronic acid capsule expression (has mutant) was increased 13-fold. In contrast, elimination of capsule expression in M2-, M3-, and M18-protein has mutants increased adherence only slightly (1.3- to 2.3-fold) compared to their respective wild-type strains. A mutant with inactivation of both emm and has displayed high-level adherence (34.9 +/- 4.1%) equal to that of the has mutant strain (40.7 + 8.0%), confirming the lack of involvement of M49 protein in attachment. Moreover, adherence of the M49-protein-deficient (emm mutant) and wild-type strains was increased to the same level (57 and 55%, respectively) following enzymatic digestion of their hyaluronic acid capsule. Adherence of mutants lacking oligopeptide permease (Opp) expression was increased 3.8- to 5.5-fold, in association with decreased cell-associated hyaluronic acid capsule. Finally, soluble CD46 failed to inhibit adherence of M49- and M52-serotype skin strains. We conclude that (i) bacterial M protein and keratinocyte CD46 do not mediate adherence of M49 skin-associated Streptococcus pyogenes to epidermal keratinocytes, (ii) hyaluronic acid capsule impedes the interaction of bacterial adhesins with keratinocyte receptors, (iii) modulation of capsule expression may be important in the pathogenesis of skin infections, and (iv) the molecular interactions in attachment of skin strains of S. pyogenes to keratinocytes are unique and remain unidentified.

Antigens, Bacterial↗
PubMed1999

Cysteine protease SpeB expression in group A streptococci is influenced by the nutritional environment but SpeB does not contribute to obtaining essential nutrients.

Group A streptococcal (GAS) cysteine protease is a major virulence factor involved in the pathogenesis of purulent and invasive infections. The secreted enzyme cleaves a number of different bacterial and host proteins which could contribute to different stages of the infective processes. It has been proposed that, among these functions, SpeB plays a role in obtaining nutrients during late growth phases. In the present study, speB mutants of various GAS serotypes were found to exhibit unaltered growth characteristics in several complex and chemically defined media (CDM). When amino acid-depleted CDM was prepared, neither SpeB activity on whole proteins added to the medium during incubation nor the addition of SpeB-digested proteins was able to support bacterial growth. SpeB also was unable to liberate iron from iron-containing protein sources added to iron-deficient CDM. However, SpeB levels in culture supernatants changed in response to the protein and glucose content of the media. Using a speB promoter-luciferase reporter, speB expression levels were found to correspond to peptide concentrations in the culture media. The effect appeared to be specific for peptides since addition of peptides derived from various proteins had an affect on expression, while addition of the whole proteins had no effect. Addition of glucose to CDM had no effect on speB expression, while glucose addition to complex medium decreased speB expression. Overall, SpeB did not appear to be directly involved in providing the bacteria with nutritional factors but expression of the speB gene responded to ratios of peptides and carbohydrates in the culture medium.

Amino Acids↗
PubMed1999

A co-stimulatory signal through ICAM-beta2 integrin-binding potentiates neutrophil phagocytosis.

The beta2 integrin LFA-1 (lymphocyte function associated antigen; CD11a/CD18) is the common ligand for the intercellular adhesion molecules (ICAMs). Integrins support cell function by providing co-stimulatory second signals that are a precondition for full cell activation first described for ICAM-1-binding to LFA-1 in lymphocytes. Integrins can also serve to activate functions associated with distinct subunits of other integrins. In addition to LFA-1, neutrophils express the beta2 integrin Mac-1 (CD11b/CD18; CR3) that apparently contains multiple sites that bind invading microbes directly or through surface-fixed C3, resulting in activation of the phagocyte function. Expression of the LFA-1 counter-receptor ICAM-1 on endothelial cells occurs only at the site of inflammation. Therefore, in neutrophils, ICAM-1 ligand binding could, as with lymphocytes, also play a part as a co-stimulatory signal to induce full phagocytotic function. We show that in neutrophils, the LFA-1 ligand interaction is the stimulatory signal to express full phagocytotic activation. This is best demonstrated by the rapid association of Streptococcus pyogenes with neutrophils, followed by ingestion, strong oxidative-burst induction and enhanced killing of these bacteria, which are well-known for their resistance to human neutrophil defense. These findings may contribute to the development of therapeutic strategies targeting the modulation of ICAM-1-leukocyte interaction.

Antibodies, Monoclonal↗