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CASE REPORT
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Year : 2020  |  Volume : 38  |  Issue : 3  |  Page : 492--495

Aspergillus mediastinitis in a post-operative immunocompetent child

Anand Kumar Mishra1, Vidur Bansal1, Gradlin Roy1, Vikram Halder1, Parakritii Gupta2, Arunaloke Chakrabarti2,  
1 Department of Cardiothoracic and Vascular Surgery, Post Graduate Institute of Medical Education and Research, Chandigarh, India
2 Department of Medical Microbiology, Post Graduate Institute of Medical Education and Research, Chandigarh, India

Correspondence Address:
Dr. Vidur Bansal
Department of Cardiothoracic and Vascular Surgery, Post Graduate Institute of Medical Education and Research, Chandigarh - 160 012
India

Abstract

Post-operative Aspergillus mediastinitis is regarded to be a devastating infection, usually affecting patients undergoing cardiothoracic surgery with specific predisposing factors characterised by a high mortality and chronic morbidity. Patient outcome after such a complication is extremely poor despite antifungal therapy and surgery. We describe the case of an immunocompetent 2-month-old child with obstructed supracardiac total anomalous pulmonary venous circulation (TAPVC) and severe pulmonary artery hypertension, who underwent TAPVC repair through median sternotomy and developed post-operative mediastinitis due to Aspergillus flavus.

How to cite this article:
Mishra AK, Bansal V, Roy G, Halder V, Gupta P, Chakrabarti A. Aspergillus mediastinitis in a post-operative immunocompetent child.Indian J Med Microbiol 2020;38:492-495

How to cite this URL:
Mishra AK, Bansal V, Roy G, Halder V, Gupta P, Chakrabarti A. Aspergillus mediastinitis in a post-operative immunocompetent child. Indian J Med Microbiol [serial online] 2020 [cited 2021 Mar 7 ];38:492-495
Available from: https://www.ijmm.org/text.asp?2020/38/3/492/299822

Full Text



 Introduction



Although the overall mortality from cardiac operations has greatly decreased in recent years, post-operative mediastinitis remains a life-threatening complication in 1%–2% of patients, with Aspergillus being the etiological agent in only a handful of cases. While bacteria are the more common pathogens, fungal infections are rare. Aspergillus infections mainly affect patients who are immunocompromised and are extremely rare in immunocompetent individuals.[1] A review of the literature emphasises that a successful treatment is exceedingly rare, and determining the optimal therapy is needed. Aggressive surgical management with mediastinal drainage, surgical debridement and early wound closure with vascularised flaps are essential to minimise the otherwise high morbidity and mortality of Aspergillus mediastinitis along with appropriate antifungal therapy.[2]

 Case Report



A 2-month-old infant was referred to the emergency department of our institute for a definitive intracardiac repair. He was diagnosed with obstructed supracardiac total anomalous pulmonary venous circulation and severe pulmonary artery hypertension. It was decided to go ahead with definitive repair after initial stabilisation with a median sternotomy. The child underwent a successful intracardiac repair. Primary closure of the sternum was not possible due to significant myocardial oedema, necessitating a polyvinyl chloride patch to be sutured to the skin. The child was shifted to the intensive care unit (ICU) on standard inotropes. Cefuroxime was given at the time of induction and then continued in the ICU. As per our standard protocol, the sternal dressing is usually opened on post-operative day (POD-2), and if feasible, the sternum is closed in the ICU itself. In our patient too, the sternal dressing was opened on POD-2, and a thorough lavage was given, but the sternum was left open owing to the haemodynamic instability of the child. On POD-4, the child was started on broad-spectrum antibiotic imipenem for ventilator-associated pneumonia due to Acinetobacter baumannii. It was decided to start imipenem owing to the culture sensitivity report of the endotracheal secretions and also because of the fact that A. baumannii encountered previously in our ICU usually responded to imipenem. The sternal dressing was changed on alternate days as per our standard protocol. On POD-8, at the time of dressing, infected sternal and pericardial tissue was seen [Figure 1]. The tissues were removed and sent for bacteriological and mycological analyses. Considering the clinical deterioration of the child in terms of fever and high ionotropic requirement, it was decided to start the child on antifungal therapy along with previously started antibacterial on that day itself. Intravenous liposomal amphotericin B at 3 mg/kg daily was started on POD-8. All surgical samples including sternal and pericardial tissues were processed and subjected to direct microscopy with KOH and calcofluor wet mount. These were inoculated onto brain–heart infusion agar and Sabouraud dextrose agar (SDA) with chloramphenicol and gentamicin at 25°C and 37°C. Calcofluor white mount revealed the presence of hyaline, septate hyphae [Figure 2]. After 2 days of incubation, flat, granular, yellow-green colonies were noted on the obverse of SDA with no pigmentation on reverse [Figure 3]. Lactophenol cotton blue preparation of the same showed rough hyaline conidiophore with biseriate phialides, covering the whole of the vesicle and globose, echinulate conidia, suggestive of Aspergillus flavus [Figure 4].{Figure 1}{Figure 2}{Figure 3}{Figure 4}

No bacteria were isolated from any culture. Extensive search for possible environmental contamination did not reveal any source in the operating room or in the ICU. Galactomannan assay for invasive aspergillosis was positive in the patient. In our child, culture of the pericardial tissue was positive for A. flavus. The drains placed intraoperatively were removed on successive days to minimise the sources of contamination. Despite alternate day dressings, thorough lavage, surgical debridement and potent antifungal therapy, the child succumbed to death on POD-25. Following this episode, few changes were made in the ICU and operating room and a standard protocol was put into place to manage these children with open sternum in the ICU. As a result, no such case has been reported from our centre since then.

 Discussion



Mediastinitis is a rare complication occurring in 1%–2% of cases after sternotomy for cardiac surgery and carries a high mortality rate. The U. S. Centers for Disease Control and Prevention defines Aspergillus mediastinitis as the presence of a positive culture result from a mediastinal sample, plus one of the following: (1) fever higher than 38°C or (2) chest pain or sternal instability with purulent effusion in the mediastinum or positive culture results from surgically obtained samples or blood.[3] Diagnosis is often delayed and relied on direct visualisation and culture until recently. Although galactomannan and beta-D-glucan tests are non-specific and cannot be used for diagnosis, they can be useful for monitoring fungal infections.[4]

According to Pasqualotto and Denning, the most important and crucial point for the diagnosis of Aspergillus mediastinitis in patients undergoing cardiac surgery with destructive wound infections and samples that give negative culture test results, is a high clinical suspicion. They described 500 cases of post-operative aspergillosis, of which 11 patients had mediastinitis, and all these patients were beyond the paediatric age group.[5] To the best of our knowledge, there is no recommendation issued for prophylaxis against Aspergillus infections in immunocompetent hosts.[6]

Environmental investigations did not reveal the source of contamination in our patient's case. This finding argues against an ongoing source of contamination and is in line with the absence of new cases of infections with Aspergillus among patients undergoing surgery within our hospital. Nevertheless, a point source not yet identified could not be excluded. However, there have been previous reports of outbreaks through the ventilation system of the operating theatre and the air conditioning filters of the cardiac surgery room.[7] Direct inoculation from our patient's flora could be a possible source, but this would have been revealed in previous cultures sent regularly from our ICU.

Voriconazole and amphotericin B are the only compounds licensed for the primary treatment of invasive aspergillosis.[7] It is generally recommended that treatment for invasive aspergillosis should be continued for a minimum of 6–12 weeks. In our case, liposomal amphotericin B was our first-line drug, analogous to the treatment of Aspergillus endocarditis, in which both liposomal amphotericin B and voriconazole are therapeutic options.[8] In our case, the most probable entry site of infection would have been the fact that the sternum was not closed for over 2 weeks owing to the haemodynamic instability of the child although a PVC patch was applied to cover the sternal wound. The absence of the high-efficiency particulate air filter (HEPA filter) in the ICU may also have contributed. In addition, the severity of organ dysfunction, reflected by the need for prolonged mechanical ventilation and transient immunodeficiency after major cardiac surgery, may also have contributed to the onset of Aspergillus mediastinitis.[9]

Ideally, in order to prevent such infections, the air-conditioning system in the ICU should have a laminar flow with continuous fresh air and 13–16 exchanges per minute. This should be delivered through the HEPA filter of 0.3 μ size.[10]

Few changes were made in our ICU/operating theatre complex including instalment of HEPA filters and the fact that cultures were taken from air-conditioning inlet vents, operating tables, instruments table, Heart-lung machine and anaesthesia circuit every 6 monthly. A thorough lavage with a double-packaged warm normal saline is given every 48 h in paediatric patients with an open sternum. A separate paediatric cubicle has been built in our ICU. It is desirable to have a positive pressure environment in ICU with laminar flow of air so that movement of air should be inside to outside. It is desirable to have a 1:1 ratio of patient and caregiver. The caregiver should follow universal precautions while handling the baby with open sternum. The paediatric patients are kept in a separate cubicle. Disposable ventilator circuits with a humidifier are used for every patient, and these are changed every week. All pressure monitoring lines are also changed on alternate days.

 Conclusion



Aspergillus mediastinitis mainly affects patients undergoing cardiac surgery operations with predisposing factors and is unusual in patients who are immunocompetent. Guidelines should be followed regarding the optimal management of a rare devastating complication like this one. Standard institutional protocol should be put into place regarding the management of patients with open sternum.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the parents have given their consent for images and other clinical information to be reported in the journal. The parents understand that name and initials will not be published, and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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