Lung transplantation for non-cystic fibrosis bronchiectasis

BACKGROUND

Lung transplantation (LTx) is a well-established treatment for end-stage pulmonary disease. However, data regarding microbiology and outcome of patients with non-cystic fibrosis bronchiectasis (NCFB) after lung transplantation are limited.

METHODS

A retrospective analysis between August 1992 and September 2014 of all patients undergoing lung transplantation at our program of all recipients with a primary diagnosis of bronchiectasis was performed. Microbiology of sputum and bronchoalveolar lavage specimens, lung function and clinical parameters pre- and post-LTx were assessed retrospectively. Overall survival was compared to the total cohort of lung transplant recipients at institution. The survival and development of chronic lung allograft dysfunction (CLAD) was compared in patients with and without chronic Pseudomonas aeruginosa (PSA) infection after LTx.

RESULTS

34 patients were transplanted. Median age at transplantation was 40 (IQR 33-52) years. The most common etiologies of bronchiectasis were idiopathic (41%), chronic obstructive pulmonary disease (COPD) (21%) and post-infectious (15%). The most common organism of pre- and posttransplant chronic airway infection was PSA. One-year Kaplan-Meier survival for patients with bronchiectasis was 85% and 5-year survival was 73% and similar to the entire cohort. All three patients with an associated diagnosis of immunodeficiency died due to infection and sepsis within the first year. Patients with persistent colonization with Pseudomonas aeruginosa after transplantation had worse long-term survival by trend and developed chronic lung allograft dysfunction more frequently.

CONCLUSIONS

Overall survival of patients with bronchiectasis after LTx is comparable to other underlying diseases. A reduced survival was observed in patients with the underlying diagnosis of immunodeficiency.

Resistance to infection of long-term cryopreserved human aortic valve allografts

OBJECTIVE

To analyze the in vitro antimicrobial activity of 3 antibiotic regimens (group A, gentamicin-piperacillin-vancomycin-metronidazole-amphotericin B; group B, gentamicin-piperacillin-flucloxacillin-metronidazole-amphotericin B; and group C, meropenem-vancomycin-tobramycin-colistin-amphotericin B) used in the processing of cryopreserved human ascending aortic tissue and aortic valves against Staphylococcus epidermidis and Staphylococcus aureus. The results were additionally compared with the infection resistance of cryopreserved ascending aortic tissue against Escherichia coli and Pseudomonas aeruginosa.

MATERIALS

Each of 10 cryopreserved human allografts (CHAs) was divided into 25 pieces (separating aortic wall and valve). Eighteen segments were microbiologically tested, and 7 pieces underwent scanning electron microscopy. A bacterial solution (4 mL; optical density, 0.20 ± 0.02) was used for contamination. After incubation, the optical density of the solution was measured. CHAs underwent sonication to release viable adherent bacteria. The number of attached bacteria was quantified by the colony forming units per square centimeter of CHA surface.

RESULTS

Antibiotic regimen groups B and C were more efficient than group A in eradicating gram-positive organisms adherent to the aortic wall (P < .001). Group C showed enhanced resistance against E coli compared with group A or B (P < .001), whereas group B appeared to be more effective against P aeruginosa (P < .001). With reference to each antibiotic regimen, ascending aortic tissue showed significantly less bacterial contamination with staphylococcal bacteria than valve grafts (P ≤ .01).

CONCLUSIONS

CHAs possess antibacterial activity despite long-term storage over 5 years. Antibiotic combinations applied during CHA processing have a significant influence on their infection resistance. Ascending aortic tissue shows a significantly enhanced bacterial resistance against staphylococcal bacteria compared with aortic valves.

Cardiac awake extracorporeal life support-bridge to decision?

Severe acute heart failure requires immediate intensive care unit (ICU) treatment, but prognosis and outcome of further treatment regimens largely depends on the preprocedural status of the patient. Especially, multiorgan failure including mechanical ventilation are unfavorable predictors of clinical outcome. Here, we report a strategy of immediate initiation of extracorporeal life support (ECLS) in awake and spontaneously breathing patients with acute heart failure to achieve early multiorgan recovery and gain sufficient time for further treatment planning. Twenty-three patients with severe cardiac failure refractory to standard medical management underwent ECLS treatment, after first clinical signs of cardiac failure appeared to avoid mechanical ventilation. Hemodynamic parameters and renal and liver functions were monitored. Outcome at 1 and 6 months was determined. Patients 46.1 ± 15.5 years of age were placed on ECLS due to various underlying diagnosis: ischemic heart disease (n = 6), dilatative cardiomyopathy (n = 4), myocarditis (n = 2), graft failure following heart transplantation (n = 6), or other diseases (n = 5). ECLS lasted 11.9 ± 12.9 days. Hemodynamic stabilization was achieved immediately after ECLS initiation. Vasopressors were reduced subsequently and the cardiac situation improved indicated by central venous saturation, which increased from 38.5 ± 11.3% before to 74.26 ± 8.4% (P < 0.0001) 24 h after ECLS initiation. Similarly, serum lactate levels decreased from 4.7 ± 4.6 to 1.7 ± 1.51 mmol/L (P = 0.003). Cumulative 30-day survival was 87.5%, and 6-month survival was 70.8%. In acute cardiac failure, early ECLS treatment is a safe, feasible treatment in awake patients allowing a gain of time for final decision. Moreover, this strategy avoids complications associated with sedation and mechanical ventilation and leads to recovery of secondary organ function, enabling destination therapy.

Microbial adhesion on membrane oxygenators in patients requiring extracorporeal life support detected by a universal rDNA PCR test

Extracorporeal membrane oxygenation (ECMO) represents a temporary life-saving therapy for respiratory or circulatory failure, but infections during ECMO support are a life-threatening complication. Surface-related infections of ECMO are mentioned, but rarely described in the literature. A universal rDNA polymerase chain reaction (PCR) test was used to investigate the potential microbiological colonization of membrane oxygenators (MOs) in 20 patients undergoing ECMO. The overall patient-based positivity by PCR was 45%. Gram-positive bacteria (71%) represented the most abundant microorganisms on MO surfaces, followed by Gram-negative bacteria (22%) and fungi (7%). The most frequently detected causative pathogens were staphylococci (58%). Bacterial mixed infections represented 56% of all infections. In four PCR-positive cases, the pathogens detected on the MO surfaces were also found by blood culture or by culture of specimens obtained from the infectious focus. In conclusion, hollow fiber membranes of MOs can be colonized by microorganisms and appear to be a potential source of bacterial and fungal infections in ECMO patients. These infections may pose an increased risk for clinical worsening. As a consequence, persistent septic complications have to be discussed as an indication for MO exchange. The initial results suggest that the applied PCR assay is a valuable tool to investigate MOs.

Prevention of pacemaker infections with perioperative antimicrobial treatment: an in vitro study

AIMS

The antimicrobial treatment of pacemaker casings with antiseptics (povidone-iodine or octenidine dihydrochloride) or antibiotics (vancomycin, daptomycin, cefuroxime, Tazobac, or nebacetin) was analysed in vitro for its biocompatibility and efficacy in preventing the bacterial adhesion of Staphylococcus epidermidis, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli to cardiac-implantable electrophysiological devices (CIEDs).

METHODS AND RESULTS

Titan platelets (0.4 cm&sup2;) cut from pacemaker casings were impregnated with seven different antimicrobial solutions: two antiseptics and five antibiotics. Subsequently, they were challenged with bacterial contamination by four test strains over a 24 h incubation period. Bacterial adherence was quantified using the colony-forming-unit method after cell recovery with sonication and examined with confocal laser scanning electron microscopy. Simultaneously, the biocompatibility of the antimicrobial impregnation was assessed using pre-treated titan platelets in a culture of human fibroblasts, skeletal myoblasts, and microvascular endothelial cells. After a 48 h incubation, cell vitality was measured using the 2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H/tetrazolium monosodium (WST-8) assay. The immersion of pacemaker casings in antiseptic or antibiotic solutions applies an antimicrobial coating that can significantly reduce bacterial adhesion. The studied impregnations differed in their antimicrobial efficacy and toxicity.

CONCLUSION

Compared with the two antiseptics and the other tested antibiotics, nebacetin showed the best ratio of efficacy to toxicity. Nebacetin showed good in vitro antibacterial activity against both Gram-positive and Gram-negative pathogens without impairing human cell vitality. It is a safe and effective candidate for CIED impregnation.

Aortic valve replacement in geriatric patients with small aortic roots: are sutureless valves the future?

OBJECTIVES

Aortic valve replacement (AVR) in geriatric patients (>75 years) with small aortic roots is a challenge. Patient-prosthesis mismatch and the long cross-clamp time necessary for stentless valves or root enlargement are matters of concern. We compared the results of AVR with sutureless valves (Sorin Perceval), against those with conventional biological valves.

METHODS

Between April 2007 and December 2012, 120 isolated AVRs were performed in patients with a small annulus (<22 mm) at our centre. In 70 patients (68 females, age 77.4 ± 5.5 years), conventional valves (C group) and in 50 patients (47 females, age 79.8 ± 4.5 years), sutureless valves (P group) were implanted. The Logistic EuroSCORE of the C group was 16.7 ± 10.4 and that of the P group 20.4 ± 10.7, (P = 0.054). Minimal-access surgery was performed in 4.3% (3/70) patients in the C group and 72% (36/50) patients in the P group.

RESULTS

The cardiopulmonary bypass (CPB) and cross-clamp times of the C group were 75.3 ± 23 and 50.3 ± 14.2 min vs 58.7 ± 20.9 and 30.1 ± 9 min in the P group, (P < 0.001). In the C group, two annulus enlargements were performed. Thirty-day mortality was 4.3% (n = 3) in the C group and 0 in the P group, (n.s.). At follow-up (up to 5 years), mortalities were 17.4% (n = 12) in the C group and 14% (n = 7) in the P group, (n.s.).

CONCLUSIONS

This study highlights the advantages of sutureless valves for geriatric patients with small aortic roots reflected by shorter cross-clamp and CPB times, even though most of these patients were operated on via a minimally invasive access. Moreover, due to the absence of a sewing ring, these valves are also almost stentless, with greater effective orifice area (EOA) for any given size. This may potentially result in better haemodynamics even without the root enlargement. This is of advantage, as several studies have shown that aortic root enlargement can significantly increase the risks of AVR. Moreover, as seen in this series, these valves may also enable a broader application of minimally invasive AVR.

Antibiotic pretreatment of heart valve prostheses to prevent early prosthetic valve endocarditis

BACKGROUND AND AIM OF THE STUDY

Prosthetic valve endocarditis (PVE), a rare but major complication after heart valve replacement surgery, has potentially catastrophic consequences despite maximal treatment. Thus, preventive measures are essential. The study aim was to investigate the effect of pretreating heart valve prostheses with the antibiotics baneomycin and daptomycin, with and without surgical sealant fibrin glue as a drug-releasing substance. The biocompatibility of baneocin and daptomycin was also investigated.

METHODS

Samples of polyethylene terephthalate (PTE), as used for the sewing cuffs of prosthetic heart valves, were tested; untreated samples served as controls. All samples were contaminated with Staphylococcus epidermidis, and colony-forming units (CFUs) then counted. Cytotoxicity tests were performed using the MTT-assay to evaluate the effects of baneomycin and daptomycin on cell proliferation and wound healing.

RESULTS

Untreated and fibrin glue-coated samples were directly infected with a bacterial count of 2.82 +/- 0.63 x 10(5) CFU/ml and 2.80 +/- 1.07 x 10(5) CFU/ml, on average. Baneocin-impregnated samples were sterile for 1.9 +/- 0.38 days, with a subsequent bacterial count of 2.26 +/- 0.6 x 10(5) CFU/ml, while daptomycin-impregnated samples were sterile for 2.9 +/- 0.38 days, with a subsequent bacterial count of 1.81 +/- 0.53 x 10(5) CFU/ml. Samples coated with a fibrin glue-baneocin mixture were sterile for 3.14 +/- 0.38 days, after which the bacterial count was 0.74 +/- 0.47 x 10(5) CFU/ml. After coating with a fibrin glue-daptomycin mixture, samples were sterile for 7.0 +/- 0.58 days, and the bacterial count was 0.70 +/- 0.56 x 10(5) CFU/ml.

CONCLUSION

In this in-vitro study, the pretreatment of prosthetic heart valves with antibiotics reduced the risk of bacterial adhesion and consequent infection. The combination of antibiotics with fibrin glue prolonged this preventive effect, with baneocin demonstrating a better biocompatibility than daptomycin. On the basis of its antibacterial efficacy, daptomycin appears to be a more suitable antibiotic to prevent early PVE with Gram-positive bacteria. The soaking of prosthetic heart valves in antibiotic solutions prior to implantation, in combination with fibrin glue in cases of suspected endocarditis, can prevent the development of early PVE. This preventive strategy should be investigated for use as a standard procedure in clinical practice.

Influence of DNA base sequence on the binding energetics of actinomycin D

The influences of base sequence on the thermodynamic properties associated with the interaction of actinomycin D with DNA are examined. It has been previously established that GpC steps of double-helical DNAs are highly preferred binding sites for actinomycin D. In this study, a series of oligonucleotides was designed and synthesized to probe the effects of flanking base sequence (adjacent to the GpC step) and novel non-GpC binding sites on the binding of actinomycin D. The use of these oligonucleotides provides a direct method for quantitating sequence specificities and actinomycin D binding energetics. Effects of different 5' and 3' flanking nucleotides on the interactions of actinomycin with the core GpC binding sites were examined using UV-visible spectrophotometric methods, and changes in binding energetics were quantitated. These studies demonstrate strong actinomycin D binding affinities to both classical GpC and an atypical non-GpC site. Enthalpy and entropy components of the DNA binding energetics for the GpC binding sites are compared and correlated with those determined for actinomycin D binding to the high-affinity non-GpC site of an 11-mer containing TGGGT as the central sequence. This TGGGT site, first suggested to be a high-affinity sequence in our earlier photoaffinity labeling studies, exhibits binding of actinomycin D comparable in strength to that of traditional actinomycin D binding sites (i.e., GpC steps). From these studies, the overall affinity and specific thermodynamic contributions (delta H degree, delta S degree) to binding of actinomycin D are demonstrated to be highly influenced both by the sequence at the intercalation site and by neighboring bases which flank the intercalation site.