Heater-cooler units: contamination of crucial devices in cardiothoracic surgery.

BACKGROUND: Several cases of Mycobacterium chimaera infection have recently been reported in cardiosurgical patients. So-called heater-cooler units (HCUs) used in cardiosurgical procedures are suspected to be the reservoir for pathogen growth and dissemination. AIM: To assess the contamination status of HCUs at our facility. METHODS: Air sampling for mycobacteria was conducted at different distances from the machines and in the area around the operating table. Air sampling was also conducted for non-fermenters as a surrogate parameter for water-associated pathogens. FINDINGS: Mycobacterium chimaera was detected in the water tanks of the HCUs. When the devices were operating, M. chimaera was also found in their exhaust air, as well as in the area around the operating table. Non-fermenters were identified at different distances from the running HCU and the area around the operating table. Cultures remained negative when the devices were switched off. CONCLUSIONS: Exhaust air from HCUs may be a pathway of pathogen transmission to patients undergoing open chest heart surgery. Although, for technical reasons, relocation of HCUs is difficult to achieve, only strict separation of the HCU from the operating room appears to enhance patient safety. Using non-fermenters as a surrogate parameter may be considered a viable option for a timely risk assessment. The design of HCUs should be modified to keep susceptibility to contamination at a minimum.

Serum (1 → 3)-ß-D-glucan measurement as an early indicator of Pneumocystis jirovecii pneumonia and evaluation of its prognostic value.

Pneumocystis jirovecii (carinii) pneumonia (PJP) is a major cause of disease in immunocompromised individuals. However, until recently no reliable and specific serological parameters for the diagnosis of PJP have been available. (1 → 3)-ß-D-Glucan (BG) is a cell wall component of P. jirovecii and of various other fungi. Data from the past few years have pointed to serum measurement of BG as a promising new tool for the diagnosis of PJP. We therefore conducted a retrospective study on 50 patients with PJP and 50 immunocompromised control patients to evaluate the diagnostic performance of serum BG measurement. Our results show an excellent diagnostic performance with a sensitivity of 98.0% and a specificity of 94%. While the positive predictive value was only 64.7%, the negative predictive value was 99.8% and therefore a negative BG result almost rules out PJP. BG levels were already strongly elevated in an average of 5 days and up to 21 days before microbiological diagnosis demonstrating that the diagnosis could have been confirmed earlier. BG levels at diagnosis and maximum BG levels during follow-up did not correlate with the outcome of patients or with the P. jirovecii burden in the lung as detected by Real-Time PCR. Therefore, absolute BG levels seem to be of no prognostic value. Altogether, BG is a reliable parameter for the diagnosis of PJP and could be used as a preliminary test for patients at risk before a bronchoalveolar lavage is performed.

[Classification and diagnostics of multiresistant bacteria]. / Klassifizierung und Nachweis multiresistenter Erreger.

Multidrug-resistant organisms are spreading worldwide. Chromosomally encoded resistance mechanisms are spread by clonal expansion, e.g., methicillin-resistant Staphylococcus aureus strains. Plasmid-encoded mechanisms such as extended-spectrum beta-lactamases spread even more efficiently because they can also be horizontally transferred into other species. Acquisition of additional resistance genes minimizes therapeutic options and leads to frequent treatment failure. Laboratory diagnostics is laborious and time-consuming and requires combinations of different phenotypic and molecular methods. Increasing knowledge of treatment and diagnostics is essential for physicians.

Extended-spectrum beta-lactamase-producing Enterobacter cloacae in mobile dialysis units in the medical and surgical departments of a university hospital: a case-control study.

The objective of this case-control study was to investigate the source of contamination and risk factors for colonisation and infection during an outbreak of extended-spectrum beta-lactamase (ESBL)-producing Enterobacter cloacae in the University Medical Center Freiburg. A risk factor analysis was performed on 23 patients with ESBL-producing E. cloacae in the medical and surgical departments by comparing them with 46 non-colonised controls, who were matched for ward and length of hospital stay. For these, a risk factor analysis was conducted. Suspected sources for transmission of ESBL were examined and staff received training in infection control measures. The higher risk in colonised patients was attributed to dialysis with mobile units [odds ratio (OR): 4.00; 95% confidence interval (CI): 1.05-15.234; P=0.04]. Dialysis units were examined, but no contamination was found. Improvement in dialysis procedures, additional staff training and renewed training in standard precautions led to a substantial fall in case numbers. Risk factor analysis showed that colonised patients carried more invasive devices than controls (central venous catheter: OR: 2.50; 95% CI: 0.74-8.45; P=0.14; Foley catheter: 5.08; 0.61-42.23; P=0.13) and were given a greater number of different antibiotics (penicillins: 2.52; 0.71-8.89; P=0.15; fluoroquinolones: 2.37; 0.77-7.28; P=0.13). The differences in mobile dialysis frequency and antibiotic use between cases and controls were relevant, although the latter was not statistically significant. It was possible to contain the high frequency of ESBL colonisation or infection by reinforcing infection control measures and training the staff involved.

[Diagnostics for endophthalmitis]. / Diagnostik bei Endophthalmitis.

Infectious endophthalmitis is a serious complication of intraocular surgery, perforating injury, or septic dissemination. Detection of the causative microorganisms is essential for effective treatment. Published positive culture rates vary from 24 to 95 %. To achieve a high positive rate of detection of microorganisms all material necessary to set up a culture has to be available in the operation theatre. Important is a variety of appropriate culture media: we use Columbia, Hematin, ENDO and yeast-cysteine blood plates as well as a nutrient solution. Samples may be brought into the culture media directly within the operation theatre. If no immediate transport to a specialised laboratory is possible, media may be cultured in the eye hospital under optimal conditions. Concurrently, undiluted samples should be used for eubacterial PCR. While standard PCR can only detect the causative microorganism, standard culture procedures provide additional information regarding resistance to anti-microbiologic therapies. In the case of presumed fungal endophthalmitis the collected vitrectomy fluid has to be centrifuged and thereafter cultured. In presumed endogenous endophthalmitis also extraocular samples should be examined (e. g., blood culture and smears from other sites of infection). With this approach a high detection rate can be achieved in patients with endophthalmitis.

Peptide adsorption on a hydrophobic surface results from an interplay of solvation, surface, and intrapeptide forces.

The hydrophobic effect, i.e., the poor solvation of nonpolar parts of molecules, plays a key role in protein folding and more generally for molecular self-assembly and aggregation in aqueous media. The perturbation of the water structure accounts for many aspects of protein hydrophobicity. However, to what extent the dispersion interaction between molecular entities themselves contributes has remained unclear. This is so because in peptide folding interactions and structural changes occur on all length scales and make disentangling various contributions impossible. We address this issue both experimentally and theoretically by looking at the force necessary to peel a mildly hydrophobic single peptide molecule from a flat hydrophobic diamond surface in the presence of water. This setup avoids problems caused by bubble adsorption, cavitation, and slow equilibration that complicate the much-studied geometry with two macroscopic surfaces. Using atomic-force spectroscopy, we determine the mean desorption force of a single spider-silk peptide chain as F = 58 +/- 8 pN, which corresponds to a desorption free energy of approximately 5 k(B)T per amino acid. Our all-atomistic molecular dynamics simulation including explicit water correspondingly yields the desorption force F = 54 +/- 15 pN. This observation demonstrates that standard nonpolarizable force fields used in classical simulations are capable of resolving the fine details of the hydrophobic attraction of peptides. The analysis of the involved energetics shows that water-structure effects and dispersive interactions give contributions of comparable magnitude that largely cancel out. It follows that the correct modeling of peptide hydrophobicity must take the intimate coupling of solvation and dispersive effects into account.

Gunshot-related displacement of skin particles and bacteria from the exit region back into the bullet path.

In previous studies, it was shown that there is a gunshot-related transport of skin particles and microorganisms from the entrance region into the depth of the bullet path. The present study deals with the question of whether gunshots may also cause a retrograde transport of skin particles and microorganisms from the bullet exit region back into the bullet path. For this purpose, we used a composite model consisting of rectangular gelatin blocks and pig skin. The skin pieces were firmly attached to the gelatin blocks on the side where the bullet was to exit. Prior to the test shots, the outer surface of the pig skin was contaminated with a thin layer of a defined bacterial suspension. After drying the skin, test shots were fired from a distance of 10 m using cartridges calibre .38 spec. with different bullet types. Subsequent analyses showed that in all shots with full penetration of the composite model, the bullet path contained displaced skin particles and microorganisms from the skin surface at the exit site. These could be regularly detected in the distal 6-8 cm of the track, occasionally up to a distance of 18 cm from the exit hole. The distribution of skin particles and microorganisms is presented and the possible mechanism of this retrograde transport is discussed.

Gunshot-related transport of micro-organisms from the skin of the entrance region into the bullet path.

The skin defect of a gunshot entrance wound is caused by the retrograde and anterograde displacement of skin particles. In the present study, we investigated whether gunshots to bacterially contaminated skin are associated with the transport of micro-organisms into the bullet path. The shots were fired into composite models of pig skin and gelatin blocks. The outer surface of the skin was covered with a thin layer of a defined bacterial suspension [green fluorescent protein-labelled Escherichia coli in the preliminary test and Staphylococcus epidermidis, DSM 1798, in the main test series]. After the bacterially contaminated fluid had dried, test shots were fired from a distance of 5 and 10 m using calibre .38 Special cartridges with different bullet types (round nose, truncated cone, hollow point and flat nose). Subsequent bacteriological analyses showed that all the bullet tracks in the gelatin serving as tissue simulant contained displaced micro-organisms from the skin surface. The results are presented and discussed with reference to the transport of skin particles into the depth of the wound track.

Spread of ampicillin/vancomycin-resistant Enterococcus faecium of the epidemic-virulent clonal complex-17 carrying the genes esp and hyl in German hospitals.

The incidence of vancomycin-resistant Enterococcus faecium isolation was low (

Tissue defect at the gunshot entrance wound: what happens to the skin?

To investigate the question what happens to the tissue lost at the entrance wound, experimental studies were performed on composite models consisting of dyed pig skin and gelatin blocks. For the test shots to the skin-gelatin preparations, cartridges calibre .38 spec. with different bullet types (round nose, hollow point, flat nose, truncated cone) were used. In all shots, a multitude of coloured skin particles were macroscopically discernible along the bullet tracks. In addition, small cell aggregations could be demonstrated microscopically even in those sections of the bullet paths which did not show skin fragments visible to the naked eye. The distribution of the skin particles showed certain peculiarities depending on the type of projectile.

Tuberculous meningoencephalitis in HIV-seronegative patients: variety of clinical presentation and impact on diagnostics and treatment.

UNLABELLED: Tuberculous meningoencephalitis (TBM), an infrequent disease in Western European countries, shows a wide heterogeneity of clinical symptoms. MATERIAL AND METHODS: We present 4 patients (age range 42-72 years) with the definite diagnosis of isolated TBM. All patients were HIV-seronegative, only 1 patient was known to be immunoincompetent on admission due to acute myelocytic leukemia; other reasons for immune suppression were detected in 2 other patients (leukemia and idiopathic CD4+ T-lymphocytopenia, respectively). RESULTS: The diagnosis of TBM was confirmed in 3 cases by culture from CSF, in 1 case Mycobacterium tuberculosis was proven only in tracheal aspirate. In 1 patient M. bovis was found, which is an extremely rare cause of TBM in Germany. We report the contributions of different diagnostic tools (CSF analysis, neuroimaging) in reaching the presumptive diagnosis and in monitoring the further course. All patients developed neurological complications despite prompt tuberculostatic treatment. Three of the patients presented a chronic severe loss of consciousness of unclear origin. CONCLUSION: The possible causative relationships of these complications and their impact on the prognosis are discussed.

Immunogenicity of an E. coli extract after oral or intraperitoneal administration: induction of antibodies against pathogenic bacterial strains.

For the treatment of recurrent infections of the urinary tract, a bacterial extract (OM-89) consisting of immunostimulating components derived from 18 Escherichia coli strains is orally applied to patients. We investigated in a mouse model the immunogenicity of the bacterial extract after intraperitoneal or oral administration. After repeated administration of the extract, serum IgG and IgA responses against the E. coli strains used for the preparation of OM-89 were obtained. This antisera also recognized a number of bacterial strains isolated from patients with urinary tract and enterohemorrhagic E. coli infections, and bound to a variety of other pathogenic strains. Moreover, the supernatants of cell cultures prepared from the urogenital tract of mice immunized with OM-89 contained increased levels of strain specific and of total IgG and IgA. Our findings may contribute to explain the therapeutic effect of OM-89 demonstrated in clinical studies.

A second unrelated bone marrow transplant: successful quantitative monitoring of mixed chimerism using a highly discriminative PCR-STR system.

A second bone marrow transplant (BMT) might be considered as an option in patients with leukaemia with graft failure after BMT. We report the successful treatment of a patient with graft failure by a second stem cell transplant from another unrelated donor. We evaluated the usefulness of an unrelated donor as the source of the second BMT in this clinical setting. In addition to this, a penta PCR-STR system was tested and shown to be sensitive for monitoring of marrow engraftment. The conditioning regimen for the first transplantation consisted of busulfan and cyclophosphamide while anti-thymocyte globulin and CY were used for the second BMT. The patient successfully engrafted at day +11 after second BMT.

Detection of cytomegalovirus DNA in CD34+ cells from blood and bone marrow.

Infection of hematopoietic progenitor cells with the human cytomegalovirus (HCMV) has been proposed as an explanation for the cytopenias associated with HCMV-related disease. To test this hypothesis, CD34+ cells, which include the hematopoietic progenitors, as well as mature leukocyte populations were purified on a fluorescence-activated cell sorter and analyzed for HCMV DNA by polymerase chain reaction (PCR). A total of 33 samples from 31 immunosuppressed as well as immunocompetent HCMV-seropositive individuals were studied. CD34+ cells were PCR-positive in four of seven bone marrow aspirates from allogeneic bone marrow transplant recipients, in three of eight aspirates from patients with acquired immunodeficiency syndrome, and in the first of two bone marrow samples from an immunocompetent patient with primary HCMV disease. CD34+ cells purified from peripheral blood for autologous and allogeneic transplantation were also analyzed, and 4 of 13 samples were HCMV DNA-positive. Interestingly, two of the four HCMV-positive samples were from healthy allogeneic donors. Among the mature leukocyte populations, the monocytes were most frequently found to be HCMV DNA-positive. No HCMV DNA was detected in the total bone marrow leukocytes of 13 healthy seropositive bone marrow donors or in the CD34+ cell fraction of three further seropositive donors. In conclusion, the data provide strong evidence that CD34+ hematopoietic progenitor cells can be infected with HCMV in immunosuppressed patients, while this cell population was not identified as a major viral reservoir in healthy HCMV-seropositive individuals.

Human cytomegalovirus immediate early and late transcripts are expressed in all major leukocyte populations in vivo.

Leukocyte populations were purified by fluorescence-activated cell sorter and analyzed for human cytomegalovirus (HCMV) DNA and mRNA using polymerase chain reaction (PCR) and cDNA PCR, respectively. Twenty-two blood samples from 17 patients with active HCMV infection were studied. HCMV DNA was detected most frequently in granulocytes and monocytes but was also found in CD4+, CD8+, and CD19+ lymphocytes. Viral immediate early and late mRNA was found in ficoll-enriched mononuclear cells and polymorphonuclear leukocytes. In 11 samples from 9 patients with active HCMV infection, immediate early mRNA was detected in 8 lymphocyte, 6 monocyte, and 8 granulocyte fractions. Late mRNA was detected in 7 lymphocyte, 7 monocyte, and 9 granulocyte fractions. The presence of viral late mRNA provides strong evidence for infection of these leukocyte populations with HCMV in vivo.

Human cytomegalovirus immediate early and late transcripts in peripheral blood leukocytes: diagnostic value in renal transplant recipients.

Peripheral blood leukocytes of renal transplant recipients were investigated to compare the following markers of human cytomegalovirus (HCMV) infection: pp65 antigen by indirect immunofluorescence, viral DNA by nested polymerase chain reaction (PCR), and immediate early (IE) and late (pp150) mRNA by nested PCR following reverse transcription. Sixty-five patients were monitored weekly for 20 weeks after transplantation. In 76 samples from 20 patients positive for HCMV DNA by PCR, HCMV mRNA was detected. Detectable amounts of IE and pp150 mRNA were positively correlated with high numbers of pp65 antigen-positive cells and confirmed the significance of pp65 antigen as a marker for active viral replication. However, with respect to the early diagnosis of HCMV-related disease and monitoring of antiviral therapy, the test for viral mRNA was not superior to the pp65 antigen test.