Is it possible to cure mediastinitis in patients with major postcardiac surgery complications?

Characteristics and outcomes of patients with postoperative Candida versus bacterial mediastinitis: a case-matched comparative study

OBJECTIVES

Postoperative mediastinitis, a feared complication after cardiac surgery, is associated with high mortality, especially of critically ill patients. Candida species infections are rare and severe, with poorly known outcomes. We conducted a case-control study to describe the characteristics, management and outcomes of patients with postoperative Candida mediastinitis.

METHODS

This French, monocentre, retrospective study included all patients with postoperative Candida mediastinitis (January 2003-February 2020) requiring intensive care unit admission. Candida mediastinitis patients (henceforth cases) were matched 1:1 with postoperative bacterial mediastinitis (henceforth control), based on 3 factors during mediastinitis management: age >40 years, cardiac transplantation and invasive circulatory device used. The primary end point was the probability of survival within 1 year after intensive care unit (ICU) admission.

RESULTS

Forty cases were matched to 40 controls. The global male/female ratio was 2.1, with mean age at admission 47.9 ± 13.8 years. Candida species were: 67.5% albicans, 17.5% glabrata, 15% parapsilosis, 5.0% tropicalis, 2.5% krusei and 2.5% lusitaniae. The median duration of mechanical ventilation was 23, 68.8% of patients received renal replacement therapy and 62.5% extracorporeal membrane oxygenation support. The probability of survival within the first year after ICU admission was 40 ± 5.5% and was significantly lower for cases than for controls (43 ± 8% vs 80 ± 6.3%, respectively; Log-rank test: P < 0.0001). The multivariable Cox proportional hazards model retained only renal replacement therapy [hazard ratio (HR) 3.7, 95% confidence interval (CI) 1.1-13.1; P = 0.04] and Candida mediastinitis (HR 2.4, 95% CI 1.1-5.6; P = 0.04) as independently associated with 1-year mortality.

CONCLUSIONS

Candida mediastinitis is a serious event after cardiac surgery and independently associated with 1-year mortality. Further studies are needed to determine whether deaths are directly attributable to Candida mediastinitis.

Diagnostic value of ⁹⁹mTc-HMPAO-labeled leukocytes scintigraphy in suspicion of post-sternotomy mediastinitis relapse

BACKGROUND

The diagnostic value of radiolabeled white blood cells (WBCs) scintigraphy in mediastinitis is well established, but data in the specific context of relapse are lacking. The present study aimed at evaluation of the diagnostic value of WBCs scintigraphy in suspicion of mediastinitis relapse after prior surgical revision.

METHODS AND RESULTS

Multiple planar incidences of the chest were acquired 4 and 20 hours after injection of labeled WBC in 43 patients. In case of non-conclusive scintigraphy, a second scan was performed 2-3 weeks after the first one. The diagnosis of infection was based on positive bacteriological results; otherwise patients were followed up for at least 1 year. Out of 39 analyzable patients, 17 (44%) were diagnosed with mediastinitis relapse. After the first scan, 32 of 39 were correctly classified, 2 were false positive, and 5 were not conclusive. After completion of an additional scan in the latter 5 patients, 36 of 39 were correctly classified and 3 were false positive (100% sensitivity, 86% specificity, 85% positive predictive value, and 100% negative predictive value).

CONCLUSIONS

In the specific context of suspicion of mediastinitis relapse, the optimal diagnostic value was achieved by repeating the scan when the first one was not conclusive. In this context, a negative WBC scintigraphy was able to rule out infection, with potential major impact on therapeutic management in patients with poor clinical status.

Hyperbaric oxygen therapy with topical negative pressure: an alternative treatment for the refractory sternal wound infection

Sternal osteomyelitis is a potentially lethal complication after cardiac surgery. It may be the cause of postoperative morbidity and mortality. We present a case of deep sternal wound infection after sternotomy. The patient received three treatments of surgical debridement, irrigation, topical negative pressure (TNP) dressing, and hyperbaric oxygen (HBO) therapy. Forty-five HBO therapy sessions were administered. After nine weeks, the sternal wound was healed and completely epithelialized. This conservative therapy can be an alternative and inexpensive method for the difficult sternal wound infection patient.

Comparison and evaluation of experimental mediastinitis models: precolonized foreign body implants and bacterial suspension inoculation seems promising

Background

Post-sternotomy mediastinitis (PSM) is a devastating surgical complication affecting 1–3% of patients that undergo cardiac surgery. Staphylococcus aureus is one of the most commonly encountered bacterial pathogen cultured from mediastinal samples obtained from patients with PSM. A component of the membrane of the gram positive bacteria, lipoteichoic acid, stimulates the blood monocytes and macrophages to secrete cytokines, radicals and nitrogen species leading to oxido-inflammatory damage. This seems to be responsible for the high mortality rate in PSM. For the evaluation of the pathogenesis of infection or for the investigation of alternative treatment models in infection, no standard model of mediastinitis seems to be available. In this study, we evaluated four mediastinitis models in rats.

Methods

The rats were divided into four groups to form different infection models. Group A: A suspension of 1 × 10⁷ colony-forming units Staphylococcus aureus in 0,5 mL was inoculated from the right second intercostal space into the mediastinum. Group B: A hole was created in the right second intercostal space and a piece of stainless-steel implant with a length of 0.5 cm was inserted into the mediastinum and a suspension of 1 × 10⁷ cfu bacteria in 0,5 mL was administered via the tail vein. Group C: Precolonized stainless-steel implant was inserted into the mediastinum. Group D: Precolonized stainless-steel implant was inserted into the mediastinum and the bacteria suspension was also injected into the mediastinum. On the 10^th day, rats were sacrificed and the extension of infection in the mediastenae was evaluated by quantitative cultures. Myeloperoxidase activity (MPO) and malondialdehyde (MDA) levels were determined in the sera to evaluate the neutrophil activation and assess the inflammatory oxidation.

Results

The degree of infection in group C and D were 83.3% and 100% respectively (P < 0.001). MDA levels were significantly higher in these two groups than the others (P < 0.001).

Conclusion

Infected implants and high bacterial concentration administration were the two important components that played a significant role in the outcome of a successful infection in mediastinum in a rat model.

Management of Intractable Sternal Wound Infections with Topical Negative Pressure Dressing

BACKGROUND

Sternal osteomyelitis after cardiac surgery is a life-threatening complication. The potential spread of infection into the mediastinum, involving the prosthetic valve, grafts, and suture lines, makes this an extremely serious complication confronting both cardiac and plastic surgeons.

AIM

Topical negative pressure (TNP) dressing has been proven to be effective for wound healing. We want to take advantages of this equipment to improve the results of intractable sternal wound infection. The results are discussed.

METHODS

From December 1996 to July 2002, 25 patients with sternal wound infections were treated at Kaohsiung Medical University Hospital. Nine patients suffering intractable sternal osteomyelitis were managed with debridement and TNP dressings. These patients received 1-3 debridements (an average of 2.2 debridements), and the average TNP dressing treatment period was 20.2 days (ranging from 3 to 43 days). After management, the infections were controlled and healthy vascularized wounds were achieved. Then, flap reconstruction could be performed for complete wound closure. Seven of the nine patients survived, and there was no recurrence of sternal osteomyelitis during follow-up period (ranging from 5 to 70 months).

CONCLUSION

The advantages of applying TNP dressings in cases of intractable sternal wound infections include (1) protecting the underlying mediasternal structure from infection, (2) permitting delayed sternal closure to avoid cardiac compression induced compromised cardiopulmonary function, (3) possibility of repeated wound inspection and bedside debridement, (4) cost-effectiveness of wound care, and (5) providing an option to promote sternal wound secondary healing for patients in poor physical condition.

The Impact of Methicillin Resistance on the Outcome of Poststernotomy Mediastinitis Due toStaphylococcus aureus

The impact of methicillin resistance on morbidity and mortality among patients with severe Staphylococcus aureus infection remains highly controversial. We retrospectively analyzed patients with mediastinitis due to methicillin-susceptible S. aureus (MSSA; 145 patients) or methicillin-resistant S. aureus (MRSA; 73 patients) who were treated with closed drainage using Redon catheters. Initial empirical antibiotic therapy was appropriate for every patient. Patients with MRSA mediastinitis were older, had higher disease severity scores at admission to the intensive care unit (ICU), and had longer periods of MRSA incubation. Multivariate analysis revealed that ICU mortality was associated with age of > or =65 years, incubation time of < or =15 days, bacteremia, higher Acute Physiology and Chronic Health Evaluation II score, and receipt of mechanical ventilation > or =2 days after surgical debridement, but not with methicillin resistance. After adjustment, durations of mechanical ventilation and Redon catheter drainage were similar for both groups (for patients infected with MRSA, only the time to mediastinal effluent sterilization remained longer). Methicillin resistance did not significantly affect ICU mortality among patients with poststernotomy mediastinitis who benefited from optimal treatments.

Mediastinitis after pediatric cardiac surgery: a 15-year experience at a single institution

BACKGROUND

The spectrum of sternal wound infections after cardiac surgery ranges from superficial infections to a deep sternal infection known as mediastinitis. Mediastinitis is a rare but clinically relevant source of postoperative morbidity and mortality in adult and pediatric patients after cardiac surgery.

METHODS

We retrospectively identified all patients diagnosed with mediastinitis after cardiac surgery from January 1987 to December 2002 (17 patients/7,616 surgeries = 0.2%). Demographic data, cardiac diagnosis, cardiac surgery, hospital length of stay, associated medical diagnosis, and surgical treatment for mediastinitis were collected.

RESULTS

Fifteen pediatric patients (age < 18 years) were diagnosed with mediastinitis (mean age at diagnosis 37.5 months, range 21 days to 17 years. The median postoperative day of diagnosis was 14 days (6 to 50 days). The most common organism was Staphylococcus species (n = 9). Six patients had an associated bacteremia. The median hospital length of stay for all patients was 42.5 days (range 16 to 163 days). The hospital mortality was 1 of 15 (6%). Each patient was treated with intravenous antibiotics; sternal debridement; and rectus abdominus flap reconstruction (n = 7), pectoralis muscle flap reconstruction (n = 3), omentum reconstruction (n = 1), or primary sternal closure (n = 4). Three patients have undergone redo-sternotomy with orthotopic heart transplantation, bidirectional cavopulmonary anastomosis, and replacement of a right ventricle to pulmonary artery homograft.

CONCLUSIONS

Timely diagnosis, aggressive sternal debridement, and liberal use of rotational muscle flaps can potentially minimize the morbidity and mortality in pediatric postoperative cardiac patients. Subsequent redo-sternotomy has not been problematic.

Vertebral osteomyelitis after cardiac surgery

BACKGROUND

Mediastinitis after open-heart surgery is a serious complication that has a decreasing incidence but still a significantly high mortality rate. Back pain may develop during the course of treatment for mediastinitis, and this should suggest vertebral osteomyelitis in the differential diagnosis. Diagnosis of vertebral osteomyelitis may be difficult because of the insidious onset and delayed diagnosis, and treatment may result in serious neurologic compromise and even death of the patient.

METHODS

This retrospective study involves 5 patients who had open-heart surgery and mediastinitis that was further complicated by vertebral osteomyelitis. Average delay in diagnosis was 18 days after the onset of symptoms. Magnetic resonance imaging was the most helpful tool for diagnosis. Methicilline-resistant Staphylococcus aureus was identified as the responsible microorganism in all patients. Neurologic compromise occured (one paraplegia and one paraparesia) in 2 patients during medical treatment.

RESULTS

Along with the medical treatment, all patients were surgically treated due to either one or more of the following reasons: unresolving symptoms, sudden neurologic compromise, or impaired spinal column stability despite appropriate conservative treatment. One patient died 10 days postoperatively. The mean follow-up period for the remaining 4 patients was 47 (12 to 95) months. Complete recovery was achieved, and they were able to return to their routine daily activities.

CONCLUSIONS

Vertebral osteomyelitis should be borne in mind when a patient develops back pain during the course of mediastinitis. Suspicion, early diagnosis with appropriate imaging, and proper treatment are crucial to prevent catastrophic complications.

Treatment of recurrent staphylococcal mediastinitis: still a controversial issue

BACKGROUND

Although surgical management with early debridement and closed mediastinal irrigation has proved successful in reducing early mortality following poststernotomy deep sternal wound infection, recurrence rates are still up to 20%. This study compared the effectiveness and safety of wound dressing with granulated sugar versus early muscle flap surgery in the management of recurrent postoperative Staphylococcal mediastinitis.

METHODS

Between January 1995 and January 2002, 25 patients with severe recurrent staphylococcal mediastinitis were treated with granulated sugar wound dressing (group A) or with wound debridement, v-shape sternectomy and associated muscle flap surgery (group B). Clinical outcomes and perioperative data were analyzed. Outcomes were compared between the groups evaluating the length of time for normalization of white blood cell (WBC) count and of body temperature and length of hospital stay. Patient characteristics determining best treatment option were identified. Survival and incidence of recurrence at follow-up were also analyzed.

RESULTS

Study groups proved homogenous as to preoperative characteristics. Complete cure was achieved earlier in group A than in group B (defervescence: p = 0.0005; WBC normalization: p = 0.0001, respectively). Hospital stay was shorter in group A. A statistically significant difference was found in hospital mortality (16% overall) between the two groups with better outcomes in group A (p = 0.039). In the patient subset with the most severe preoperative profile (hemodialysis, tracheostomy, inotropic support) surgical treatment produced worse results than the sugar dressing method (p 0.048). No case of recurrence was observed.

CONCLUSIONS

Both treatments proved effective in recurrent type IV A Staphylococcal mediastinitis. Granulated sugar proved a safer option in severely compromised patients.