Early in vitro development of daptomycin non-susceptibility in high-level aminoglycoside-resistant Enterococcus faecalis predicts the efficacy of the combination of high-dose daptomycin plus ampicillin in an in vivo model of experimental endocarditis

Background

Previous studies showed development of daptomycin non-susceptibility (DNS: MIC >4 mg/L) in Enterococcus faecalis infections. However, no studies have assessed the efficacy of the combination of daptomycin/ampicillin against E. faecalis strains developing DNS in the experimental endocarditis (EE) model.

Objectives

To assess the in vitro and in vivo efficacy of daptomycin at 10 mg/kg/day, daptomycin/ampicillin and ampicillin/ceftriaxone against two high-level aminoglycoside-resistant E. faecalis strains, one developing DNS after in vitro exposure to daptomycin and another that did not (DS).

Methods

Subculture of 82 E. faecalis strains from patients with endocarditis with daptomycin MICs, time-kill and in vivo experiments using the EE model.

Results

33% of the strains (27 of 82) displayed DNS after subculture with daptomycin. Daptomycin MIC rose from 0.5-2 to 8-16 mg/L. In time-kill experiments, when using a high inoculum (10 8 cfu/mL), daptomycin/ampicillin was synergistic for one-third of DS strains and none of DNS strains, while ampicillin/ceftriaxone retained synergy in all cases. In the EE model, daptomycin did not significantly reduce cfu/g from vegetations compared with control against either strain, while daptomycin/ampicillin reduced significantly more cfu/g than daptomycin against the DS strain, but not against the DNS strain [2.9 (2.0-4.1) versus 6.1 (4.5-8.0); P  =   0.002]. Ampicillin/ceftriaxone was synergistic and bactericidal against both strains, displaying the same activity as daptomycin/ampicillin against the DS strain.

Conclusions

Performance of an Etest for daptomycin MIC after subculture with daptomycin inhibitory doses on strains of high-level aminoglycoside-resistant E. faecalis endocarditis may be an easy test to predict the in vivo efficacy of daptomycin/ampicillin.

Enterococcal endocarditis revisited

The Enterococcus species is the third main cause of infective endocarditis (IE) worldwide, and it is gaining relevance, especially among healthcare-associated cases. Patients with enterococcal IE are older and have more comorbidities than other types of IE. Classical treatment options are limited due to the emergence of high-level aminoglycosides resistance (HLAR), vancomycin resistance and multidrug resistance in some cases. Besides, few new antimicrobial alternatives have shown real efficacy, despite some of them being recommended by major guidelines (including linezolid and daptomycin). Ampicillin plus ceftriaxone 2 g iv./12 h is a good option for Enterococcus faecalis IE caused by HLAR strains, but randomized clinical trials are essential to demonstrate its efficacy for non-HLAR EFIE and to compare it with ampicillin plus short-course gentamicin. The main mechanisms of resistance and treatment options are also reviewed for other enterococcal species.

Efficacy and safety of fosfomycin plus imipenem as rescue therapy for complicated bacteremia and endocarditis due to methicillin-resistant Staphylococcus aureus: a multicenter clinical trial

BACKGROUND

There is an urgent need for alternative rescue therapies in invasive infections caused by methicillin-resistant Staphylococcus aureus (MRSA). We assessed the clinical efficacy and safety of the combination of fosfomycin and imipenem as rescue therapy for MRSA infective endocarditis and complicated bacteremia.

METHODS

The trial was conducted between 2001 and 2010 in 3 Spanish hospitals. Adult patients with complicated MRSA bacteremia or endocarditis requiring rescue therapy were eligible for the study. Treatment with fosfomycin (2 g/6 hours IV) plus imipenem (1 g/6 hours IV) was started and monitored. The primary efficacy endpoints were percentage of sterile blood cultures at 72 hours and clinical success rate assessed at the test-of-cure visit (45 days after the end of therapy).

RESULTS

The combination was administered in 12 patients with endocarditis, 2 with vascular graft infection, and 2 with complicated bacteremia. Therapy had previously failed with vancomycin in 9 patients, daptomycin in 2, and sequential antibiotics in 5. Blood cultures were negative 72 hours after the first dose of the combination in all cases. The success rate was 69%, and only 1 of 5 deaths was related to the MRSA infection. Although the combination was safe in most patients (94%), a patient with liver cirrhosis died of multiorgan failure secondary to sodium overload. There were no episodes of breakthrough bacteremia or relapse.

CONCLUSIONS

Fosfomycin plus imipenem was an effective and safe combination when used as rescue therapy for complicated MRSA bloodstream infections and deserves further clinical evaluation as initial therapy in these infections.

[Prospective and comparative study of pacemaker implants carried out at the electrophysiology laboratory and the operating room]

INTRODUCTION AND OBJECTIVES

Permanent pacemaker implantation is done by different physicians with either a surgical or clinical training. Our objective was to evaluate if there were significant differences in the implantation parameters and in the complication rate among implantations performed by cardiologists in the electrophysiologic laboratory and cardiological surgeons in the operating room.

MATERIAL AND METHODS

We prospectively collected those patients' data who received a first pacemaker implantation by cardiovascular surgeons and electrophysiologists during the year 1998. Data collected included demographic information, indication for pacing, surgical time, complications during procedure, stimulation and sensing thresholds as well as type of pacing.

RESULTS

We first-implanted 216 pacemakers in a one year period, 101 by cardiovascular surgeons and 115 by electrophysiologists. 56% were male patients. Average age in the surgery group was 74.2 +/- 9 years and 72.09 +/- 12 in the electrophysiology group (p = NS). Main diagnoses were as follows: complete heart block in 32.9% patients, complete heart block 2. degrees 16.4%, sinus node dysfunction 12.2%, AV node ablation 12.2% and others. The complications rate for surgery group was 4% and 1.7% for electrophysiologists (p = NS). Electrophysiologists placed more bicameral devices. No clinically significant differences were found among other implant parameters.

CONCLUSIONS

Pacemaker implant by cardiologists in an electrophysiologists laboratory is a safe procedure that does not have more complications when compared to the same procedure done in the operating room by surgeons. This allows hospital resource optimization and reduction of hospital stay length.

[Postinfarction ventricular septal defect. Surgical approach by right ventriculotomy in 4 patients]

Ventricular septal defect secondary to myocardial infarction still have high mortality. Early and swift surgical repair is needed to obtain adequate results. Surgical exposure of defect through the infarcted left ventricle wall is the usual technique. Nevertheless right ventricular access to the interventricular septum has given excellent results on 4 of our patients. Our results are analyzed.

[The arterial complications of closed injuries to the shoulder girdle]

After a period of time of 5 years, we made a review of all the patients registered at our Center. Eight cases of closed traumatism at the scapulohumeral belt, with vascular injury associated (0.2% of all closed traumatisms at this level registered in our center during this time) were reported. Six patients presented also an osteoarticular injury associated. Three different vascular injuries were showed: three cases of complete arterial section, two arterial contusions and a partial arterial section. From the two cases without osteoarticular injuries, one of them showed a complete section and the other presented an arterial contusion. Polytraumatic patients showed multiple osteoarticular injuries. We registered one fracture-luxation at the shoulder, 3 diafisaric humeral fractures, one humeral neck fracture, one clavicle fracture, one fracture-luxation at the cervical column and one simple luxation of the shoulder.

[Traumatic rupture of the tricuspid valve. Its conservative surgical treatment]

Tricuspid insufficiency caused by blunt chest trauma is rare and usually unsuspected clinically, early after trauma. Cross-sectional Echocardiography and Cardiac Catheterization are essential to establish the diagnosis. Therapy applied varies from repair to valvular replacement. We describe an 18-year-old boy with traumatic tricuspid regurgitation treated by reconstruction of the attachments of the anterosuperior leaflet and annuloplasty with a Puig-Massana ring. Six month after surgery he is fully recovered, although persist a moderate degree of tricuspid insufficiency.

[Aneurysms of the abdominal aorta in patients on a permanent hemodialysis program]

Surgical approach of an aneurysm at the infrarenal aorta abdominal, in six patients with terminal renal failure and chronic hemodialysis, is presented. They were all men, and the middle age was 62 years. There were two hospital deaths and a latter death. At the moment of this report, the three survival patients are well, after a follow-time of 34.6 months. Treatment of this group of patients, as well as the literature concerning to this subject are reviewed.

[Vascular injuries of the lower extremity]

Authors present their experience (32 patients affected by a traumatic femoropopliteal injury) with vascular traumatisms at the lower limb. Causes, treatment and successful results with the new technics and the early clinical management to the patients are commented.

Delayed sternal closure for life-threatening complications in cardiac operations: an update

Over a 7-year-period, 25 patients had delayed sternal closure after open heart operations out of 34 patients whose sternum was not closed. The indications were extreme cardiac dilatation and uncontrollable mediastinal hemorrhage. This represented a 1.79% incidence in the overall open heart surgical experience at our unit. Sternal closure was performed at a mean of 2.64 days after the initial operation. Eighteen patients (52.9%) left the hospital alive and well, representing a 72% survival rate among patients undergoing delayed sternal closure. No mediastinal or fatal infection developed and only 1 patient had late superficial wound infection after delayed sternal closure. We conclude that delayed sternal closure is an effective method to treat severe complications after cardiac operations.

AIDS and Salmonella-infected abdominal aortic aneurysm

The case of a bisexual male patient with acquired immunodeficiency syndrome (AIDS) and an infected abdominal aortic aneurysm requiring surgery is presented. Attention is drawn to the fact that an unpredictable number of operations will be needed in AIDS patients in the next future.

[Coarctation of the abdominal aorta. Surgical treatment]

Five cases of aortic abdominal coarctation are presented, 4 of them surgically treated (by-pass). A revision of the theme, specially its etiology and surgical options, is carried out.

Improvement of renal function in azotaemic hypertensive patients after surgical revascularization

Between 1974 and 1986, 17 patients (16 men and 1 woman) with renal insufficiency (serum creatinine greater than 1.5 mg/dl, mean 3.75 mg/dl), with a mean age of 51.3 years, underwent surgical renal revascularization. Two of them were on maintenance haemodialysis. All were severely hypertensive in spite of antihypertensive drugs. Atherosclerosis was the cause of renal stenosis in 14 cases and fibromuscular dysplasia in 3. Operative procedures included splenorenal shunt (5), autotransplantation (3), aortorenal bypass (3), hepatorenal bypass (1), bilateral renal endarterectomy (1), renal ostial closure (1) and nephrectomy (3). Mean serum creatinine showed a decrease from 3.76 to 1.65 mg/dl (P less than 0.005). Mean arterial pressure dropped from 161 mmHg to 103 mmHg (P less than 0.001). Systolic and diastolic pressures also showed significant decreases. Two patients died. Four patients required a second operation and the renal function and blood pressure then improved. Renovascular disease must be ruled out in patients with renal insufficiency associated with hypertension, including those patients on haemodialysis. We conclude that renal revascularization surgery is a reliable and efficient form of treatment in selected cases of renal failure of renovascular origin.

Complete translocation of the aortic root and coronary bypass grafting with a microporous polyurethane (Mitrathane) composite valved graft in the treatment of recurrent prosthetic valve endocarditis

The case of a 20-year-old male patient, with a history of addiction to parenteral heroin and recurrent prosthetic valve endocarditis, is presented. In this case the final procedure consisted of a complete translocation of the aortic root and coronary bypass grafting with a composite graft made from a microporous polyurethane (Mitrathane) cardiac patch, a prosthetic valve and two Mitrathane vascular grafts for the coronaries. This is a complex operation, only indicated in cases of extensive destruction of the aortic root due to recurrent endocarditis. To our knowledge, it is the first case of this type performed using Mitrathane.

Severe fibrous epicarditis after microporous polyurethane (Mitrathane) cardiac patch implantation

Several materials have been used for pericardial closure after open heart surgery. Mitrathane is a recently introduced material designed for use in the cardiovascular system. A case of severe epicarditis after implantation of a Mitrathane cardiac patch for pericardial closure is presented. This epicardial reaction rendered the exposure of the heart at reoperation extremely difficult. This is a complication not reported to date with this new material. Thus, careful evaluation of Mitrathane is needed before extending its use to larger series.

Open heart surgery for thrombosis of a prosthetic mitral valve during pregnancy. Fetal hydrocephalus

Pregnant women with cardiac valvular prostheses present an important risk factor and the major complications are endocarditis and thromboembolism. Thromboembolism is determined by a hypercoagulation state. Compulsory anticoagulation treatment is an associated risk factor producing maternal and fetal complications. Different open heart surgical cases during pregnancy have been reported and a review of the literature shows favourable maternal prognosis. A 30-year-old woman with a Björk-Shiley mitral prosthesis, during the 6th week of pregnancy presented with thrombosis and embolism due to a change in anticoagulation treatment from acenocumarol to heparin. Open heart surgery was carried out and the patient's course was favourable. A fetal hydrocephaly of unknown etiology was discovered during the 18th week of pregnancy. Open heart surgery during pregnancy and the necessity of thromboembolic prophylaxis, have been analysed and revised.

Early results with intraoperative transluminal coronary artery balloon dilatation

We used intraoperative transluminal coronary balloon dilatation, together with coronary artery bypass grafting, to obtain complete myocardial revascularization in extensively diseased coronary arteries. Our patient population consisted of ten males and two females, with a mean age of 58 years. The left anterior descending artery was dilated in five patients, the posterior descending artery was dilated in three, the obtuse marginal artery in two, the left circumflex artery in one, and the right coronary artery in one. Additionally, a mean of 2.81 grafts per patient were placed. Hospital mortality was one patient (8.33%). There was also one case of perioperative myocardial infarction. Postoperative angiography was done in seven patients: five were shown to be improved, one had a vessel that appeared unchanged, and one had an occluded vessel. We found intraoperative transluminal coronary balloon dilatation to be a simple and efficient technique that offers potential improvement in myocardial revascularization.