Fever work-up unfolds a rare diagnosis of native valve endocarditis caused by Mycobacterium abscessus

Anita Sharma; Irneet Mundi; Karun Behal; Navreet Kaur; Pooja Singh; Manish Mahant

doi:10.4103/IJPM.IJPM_19_19

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Year : 2019 | Volume : 62 | Issue : 4 | Page : 589-591

Fever work-up unfolds a rare diagnosis of native valve endocarditis caused by Mycobacterium abscessus

Anita Sharma¹, Irneet Mundi¹, Karun Behal², Navreet Kaur³, Pooja Singh¹, Manish Mahant⁴
¹ Department of Lab Medicine, Fortis Hospital, Mohali, Punjab, India
² Department of Cardiology, Fortis Hospital, Mohali, Punjab, India
³ Department of Critical Care, Fortis Hospital, Mohali, Punjab, India
⁴ Department of Cardiac Surgery, Fortis Hospital, Mohali, Punjab, India

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Date of Web Publication

14-Oct-2019

Abstract

Endocarditis caused by Mycobacterium abscessus is rare and often missed without appropriate blood cultures. It does not respond to standard antitubercular treatment and is also resistant to many other antibiotics. The course of the disease may be indolent and often results in a fatal outcome. Accurate identification and sensitivity, combination therapy, and prolonged duration of antibiotics are, therefore, important for a successful outcome.

Keywords: Endocarditis, Mycobacterium abscessus, native valve

How to cite this article:
Sharma A, Mundi I, Behal K, Kaur N, Singh P, Mahant M. Fever work-up unfolds a rare diagnosis of native valve endocarditis caused by Mycobacterium abscessus. Indian J Pathol Microbiol 2019;62:589-91

How to cite this URL:
Sharma A, Mundi I, Behal K, Kaur N, Singh P, Mahant M. Fever work-up unfolds a rare diagnosis of native valve endocarditis caused by Mycobacterium abscessus. Indian J Pathol Microbiol [serial online] 2019 [cited 2023 Jun 7];62:589-91. Available from: https://www.ijpmonline.org/text.asp?2019/62/4/589/269058

Introduction

Mycobacterium abscessus complex is a non-tuberculous, rapidly growing mycobacterium (RGM) found ubiquitously in the environment including soil, dust, and water.^[1] Infective endocarditis (IE) due to M. abscessus is rare, and to the best of our knowledge, only 15 cases have been reported in the literature so far. Most cases of IE caused by M. abscessus are seen in patients after valve replacement. We report a possible iatrogenic case of native valve endocarditis caused by M. abscessus. The case was treated favorably because of the early and correct identification of the RGM, surgical intervention, and optimized antibiotic treatment.

Case Report

A 41-year-old male presented to our hospital with a history of intermittent fever for the last 4 months, accompanied with a significant weight loss of 25 kg, loss of appetite, and generalized weakness. Detailed history revealed him to be having Type 2 diabetes mellitus, dyslipidemia, and coronary artery disease. He gave a history of a single episode of chest pain about 5 months back for which coronary angiography was done at his home town. 2D echocardiography done during that admission showed normal valves with no vegetation or clots and a left ventricular ejection fraction (LVEF) of 75%. There was no other intervention done, and the patient was managed medically. Subsequently, he started to have fever about 2 weeks after this intervention accompanied with weight loss. Investigations revealed a normal CT chest. CT abdomen revealed a splenic infarct. Most of the other tests including those for tropical fever and collagen disorders were non-contributory. He was managed for enteric fever empirically but was not relieved of his symptoms. He continued to have fever spikes with general deterioration in his health with which he presented to the emergency department of our hospital. He was admitted in the intensive care and was investigated thoroughly in the following days for possible cause of fever.

Laboratory investigations revealed Hb of 11g/dL, TLC -10.8 thous/microL, low total protein (6.3 g/dL) and albumin (3.1 g/dL), and normal liver and kidney function tests. C-reactive protein (CRP) was 55.2 mg/dl and procalcitonin was equivocal at 0.27 ng/ml. His HIV serology was non-reactive. Work-up for tropical diseases such as malaria, dengue, and leptospira was also negative.

MRI brain showed thalamic infarcts, subacute infarct of the left frontal lobe, and acute on chronic lacunar infarct along with subacute -chronic intraparenchymal hemorrhage.

2D echocardiography revealed LVEF of 55%, moderate aortic regurgitation (AR), moderate mitral regurgitation (MR), and small vegetation on aortic cusp. Two sets of blood culture were sent as a part of work-up for IE, and gentamicin and vancomycin were empirically started. The patient improved, remained afebrile for a week, and was discharged on antibiotics after 7 days of hospital stay to be followed closely on a domiciliary basis. The patient remained afebrile for about 5 days after discharge but was readmitted with history of fever, breathlessness, and symptoms of cardiac failure.

Meanwhile, Acid-Fast Bacilli (AFB) were isolated from one of the two sets of blood culture bottles taken on the day of his first admission. The bottle flagged positive on day 5 and the organism grew on Blood and Mc'cockey agar after 3 days of subculture. It was later on identified as M. abscessus sub spp abscessus(MALDI-TOF and NGS) and was taken up for antimicrobial sensitivity testing. The isolate was reported as sensitive to amikacin, tobramycin, and clarithromycin; intermediate sensitive to cefoxitin and linezolid; and resistant to trimethoprim-sulphametoxazole, ciprofloxacin, and doxycycline. On the basis of identification, the antimicrobial therapy was revised to amikacin, imipenem, and clarithromycin.

On 2^nd admission, he had low blood pressure (90/60 mm Hg), appeared sick, and had a raised total leukocyte count (TLC) of 14.8 thous/microL and creatinine of 4.2 mg/dL. In the wake of persistent vegetations and deteriorating clinical picture, he was taken up for a high-risk double valve replacement procedure 3 days later. Per-operatively large vegetation was present over left coronary cusp (LCC) of the aortic valve and another one over non-coronary cusp (NCC).

The resected aortic valve sent to the laboratory grew M. abscessus on culture. Fungal culture was negative. The histopathological examination of the valve showed fibrinous exudate with collections of polymorphs. Ziehl-Neelsen (ZN) stain demonstrated numerous AFB lying singly as well as in colonies [Figure 1]. The bacilli were also positive for Periodic acid-Schiff stain.

Figure 1: (a and b) H and E stained section of aortic valve showing fibrinous exudate and collection of polymorphs. (c and d) ZN stain highlighting numerous Acid- Fast Bacilli

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The patient responded well after surgery and was discharged subsequently on antibiotics in a stable condition. His repeat blood cultures have been sterile, and the patient has been doing well on follow-up therapy till the writing of this report around 4 months after discharge.

Discussion

Increasing utilization of foreign medical materials, indwelling catheter insertions, and intravenous (IV) drug use are recognized risk factors predisposing to bacterial IE. Staphylococcus aureus has become the most common microorganism of bacterial IE.^[2]

Mycobacterial endocarditis is rare but dreadful, and the causative pathogens are predominantly RGM.^[2] M. abscessus is considered the most pathogenic and difficult to treat of the RGM and is most often associated with pulmonary, skin, and soft tissue infections. It has also been reported to cause ocular infections, otitis, lymphadenitis, arthritis, osteomyelitis, disseminated disease, and prosthetic valve endocarditis.^[1] IE due to M. abscessus is rare, and to the best of our knowledge, only 15 cases have been reported in the literature so far [Table 1]. Native valve endocarditis caused by M. abscessus is even rarer.

Table 1: Cases of endocarditis caused by Mycobacterium abscessus

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M. abscessus endocarditis has been found to be associated with history of surgery (cardiac, valvular), foreign bodies, trauma, IV injections, hemodialysis, or immuno compromised status.^[9] Yuan SM ^[2] in their review attributed cardiac surgery to be the risk factor for IE in 54%, foreign material implant in 22%, IV drug use in 10%, and miscellaneous causes in 14% cases. Cardiac catheterization process appears to be the most likely reason of IE in the present patient as was also the case in the report by Mahajan S, et al.^[14] Environmental mycobacteria are common postprocedure pathogens, especially when disposable equipment is recycled,^[14] which is often the case in resource-challenged settings. Although this may seem inevitable in an economically challenged milieu, cleaning, disinfection, sterilization, and reuse of single-use devices need to be quality controlled to minimize the risk of any possible iatrogenic infections.

M. abscessus complex is a notoriously resistant mycobacterium often leading to poor outcomes. It contains a group of subspecies, which include M. abscessus sub spp. abscessus, M. abscessus sub spp. Bolletii, and M. abscessus sub spp. massiliense. M. abscessus sub spp. abscessus is well known for drug resistance and has been shown to be refractory to treatment. They are innately macrolide resistant because of the presence of an inducible gene that is phenotypically expressed when exposed to macrolide antibiotics. The erythromycin ribosomal methyltransferase (erm) (41) gene stimulates the expression of a diverse collection of methylases that ultimately lead to impaired binding of macrolides to the 23S ribosomal subunit, thus, preventing their inhibitory mechanism.^[15] Sub speciation of M. abscessus is, therefore, very important. Advances in diagnostics like automated blood culture systems and rapid identification like MALDI-TOF can help in starting the targeted therapy at the earliest. However, access to these advanced technologies is only limited to research institutions or metropolitan cities, and this may add to lack of or delay in identification and susceptibility testing.

Combination therapy of at least two antimycobacterial agents is recommended, but usually, three separate agents from different classes are used. A minimum duration of 4 weeks is documented in the literature, but longer periods consisting of 6–12 months are more common.^[15] Our isolate was sensitive to amikacin and clarithromycin. We did not look for the erm(41) gene as the facility was not available and hence need to follow patient closely for any breakthrough infection.

This case illustrates the role of multidisciplinary approach and advanced diagnostics in the management of a complicated, possible iatrogenic case of IE due to a rare organism. Appropriate diagnosis and timely intervention are necessary to manage this often fatal infection.

Declaration of patient consent

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

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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