Native valve endocarditis caused by E rysipelothrix Rhusiopathiae: presenting with refractory heart failure and requiring surgical valve replacement—report on a rare zoonosis

Abstract

Erysipelothrix Rhusiopathiae is a Gram-positive bacillus that is ubiquitous in nature. The bacterium is a zoonotic pathogen known to infect wild and domestic animals. Human infections, however, are uncommon and typically present with localised or generalised cutaneous lesions. Systemic infection in the form of bacteraemia with seeding to various organs is the least common form of the disease. Infections in humans tend to be associated with occupational exposure and close contact with animals. Clinical data of a 61-year-old male patient with Gram-positive bacilli bacteraemia and E. Rhusiopathiae-induced endocarditis are presented here. The patient presented with refractory congestive heart failure secondary to severe acute aortic regurgitation mandating surgical valve replacement. The described case has special clinical merit given the lack of fever and leukocytosis, absence of erysipeloid cutaneous manifestations and refractoriness to medical management. E. Rhusiopathiae should be considered in the differential diagnosis for Gram-positive bacilli bacteraemia and endocarditis. In the proper clinical setting, occupational exposure and animal contacts are helpful clues to raise suspicion for this bacillus. The high mortality associated with the pathogen should urge for early identification and initiation of antimicrobial treatment.

Background

Erysipelothrix Rhusiopathiae is a pleomorphic, non-motile, non-spore forming, Gram-positive bacilli that was first isolated from a mouse in 1876.^{1 2} The first description of human disease, however, was reported in 1879 in the form of a localised cutaneous lesion. The bacterium is ubiquitous in the nature. It is a pathogen of zoonosis that is known to infect both wild and domestic animals, including swine, pigs, poultry, mice, sheep and fish. Swine are considered the primary reservoir for the pathogen.

Infections in humans tend to be association with occupational exposure; that is, following contact with contaminated animals. Cases have been reported in abattoir workers, fish handlers, butchers and veterinarians. Chronic alcoholism has also been identified as a common underlying comorbidity. Transmission occurs via the direct inoculation of the bacilli into the skin, usually following a breach to skin integrity (ie, abrasions or puncture wound).

Human infection with this organism presents in one of three forms of the disease. These are (1) erysipeloid—a mild localised cutaneous infection, (2) a severe generalised cutaneous infection and (3) systemic infection in the form of septicaemia (with or without cutaneous involvement).^3–5 Systemic infections with E. Rhusiopathiae are the most serious but the least common forms; presenting as septicaemia with subsequent organ involvement (ie, septic arthritis, osteomyelitis, endocarditis and even cerebral infection reported in the literature).^6–8 In this report, we describe a case of a native valve endocarditis caused by E. Rhusiopathiae and presenting with severe aortic regurgitation mandating surgical valve replacement.

Case presentation

Clinical history

This is a 61-year-old male patient with a history of essential hypertension, chronic obstructive pulmonary disease and alcohol misuse. He presented to the emergency department complaining of progressively worsening shortness of breath and lower limb swelling for the past 8 weeks. He reported having a new-onset orthopnoea mandating him to use two pillows at nights. During the past 2 months, patient has also been endorsing night sweats, loss of appetite, labile weight, decreased level of energy and fatigability.

On presentation, patient denied any chest pain, palpitations, fever, cough, wheezing, headache, visual changes, abdominal pain, nausea, vomiting or skin rash. He also denied having any sick contact. His primary concern on admission was his extreme fatigability over the past 6 weeks. Further, review of the patient’s medical history was negative for congestive heart failure, coronary artery disease, valvular heart disease, rheumatic heart disease and infective endocarditis. Nonetheless, his elder brother was reported to have had cardiac surgery for undetermined aortic valve disease and aortic aneurysm.

Patient lives in a residential-farm in a rural community; where his house is juxtaposed to the farm. He works in a barn in which he reports being exposed to rodents, including mice. Patient was also exposed to bats while in the barn, but he does not recall ever being bitten. He also works with chickens that run freely in his yard and has several feral cats inside the house which has ‘scratched him’ previously. He is a handyman worker for 40 years with frequent exposure to fume and chemicals.

Patient medical history is pertinent for nicotine dependence, with a 40-pack-year smoking history and alcohol misuse. He drinks 6–8 beers (12 oz) per day. Patient quitted smoking and alcohol consumption 2 months prior to admission via a ‘detox’ programme. He denies any substance misuse.

Physical examination

On physical examination, patient was articulate but ill-appearing. Body temperature was 98°F (36.7°C), pulse rate was 106 beats/min, blood pressure was 118/44 mm Hg, respiratory rate was 17 breaths/min and oxygen saturation (SpO2) was 97%. He had decreased breath sounds at the lower lobes bilaterally along with mild dyspnoea; but with no wheezing, crackles or rales. He had regular heart rate and rhythm. A diastolic murmur was appreciated at the left upper sternal border and a 2/6 systolic murmur was also appreciated at the cardiac apex. Patient had significant jugular venous distention and bilateral lower extremity oedema (+2).

Investigations

Laboratory findings

Initial workup on admission showed a white blood cell count (WBC) of 6.9×10⁹/L, haemoglobin of 94 g/L, platelet count of 193×10⁹/L, creatinine of 0.72 mg/dL and albumin level of 3.2 g/dL. He was also found to have elevated troponin I of 690 ng/L and elevated pro-brain batriuretic peptide (BNP) of 2850 pg/mL.

Imaging

Initial transthoracic echocardiogram (TTE) performed on admission revealed severe aortic regurgitation (figure 1) and a large mobile density on the aortic valve (on the ventricular side) suggestive for vegetation or a flailed aortic valve leaflet. Patient had a preserved left ventricular (LV) systolic function with an ejection fraction (EF) of 55%. Similarly, transoesophageal echocardiogram (TOE) showed an echodensity attached to the valve leaflet (figures 2 and 3) suggestive for possible endocarditis with resultant severe aortic regurgitation (figure 4), or less likely, a flail right coronary cusp. Severe aortic regurgitation on TOE was suggested by the following echocardiographic findings: vena contracta was 0.8 cm, pressure half time was 112 ms and jet appearance was dense.

Figure 1.

Transthoracic echocardiography (parasternal long-axis view) shows severe aortic regurgitation and a widely open aortic valve. Vena contracta was 0.8 cm, pressure half time was 112 ms, and jet appearance was dense.

Figure 2.

Transoesophageal echocardiogram (mid-transoesophageal view) shows the thickened aortic leaflets with a mobile density attached to both leaflets.

Figure 3.

Transoesophageal echocardiogram (mid-transoesophageal view) shows the thickened aortic leaflets with a mobile echodensity attached to both leaflets.

Figure 4.

Transoesophageal echocardiogram (deep transgastric apical view) demonstrates the severe aortic regurgitations.

Microbiology

Blood cultures were obtained on admission and preliminary results on day 2 grew Gram-positive bacilli bacteria (in four out of four bottles). Hence, he was empirically started on intravenous vancomycin and ampicillin. On day 3, final blood culture results were positive for E. Rhusiopathiae.

Hospital course

Patient presented with tachycardia, elevated troponins and an elevated BNP on arrival. Chest X-ray demonstrated pulmonary vascular congestion, bilateral pleural effusion with bibasilar atelectasis. ECG demonstrated sinus tachycardia, right axis deviation and evidence for septal infarction of indeterminate age. Hence, patient was presumed to have non-ST elevation myocardial infarction and started on intravenous heparin drip, aspirin 81 mg and atorvastatin 80 mg. Due to new-onset congestive heart failure, patient was started on aggressive diuresis with 80 mg of intravenous lasix, before eventually transitioning to intravenous bumetanide and metolazone.

On day 2, blood culture grew Gram-positive bacilli bacteria. Hence, patient was empirically started on intravenous vancomycin and ampicillin. On day 3, final blood culture results were positive for E. Rhusiopathiae. Subsequently, antibiotic regimen was narrowed to penicillin G (4 million units, every 4 hours) for a 6 week treatment plan. Repeat blood cultures on several occasions had been negative since then.

TTE (figure 1) and TOE (figures 2 and 3) were performed on day 2 and demonstrated severe aortic regurgitation, aortic valve vegetations, right coronary artery aneurysm, reduced right ventricular function and a preserved EF (55%). Chest CT angiography was performed to rule out aortic dissection and it was negative. In addition, patient underwent right and left cardiac catheterisation on day 5 demonstrating non-obstructive coronary artery disease and severely elevated right atrial pressure.

Patient continued to be afebrile throughout the admission; however, on the sixth day, he developed significant leukocytosis (WBC count of 16.4 k/µl) for the first time since admission. He also continued to have significant shortness of breath and worsening lower limb oedema in spite of the aggressive diuresis. Chest X-ray on the sixth day showed persistent pulmonary vascular congestion with no improvement in the pleural effusion bilaterally. Complete pulmonary function test showed moderate restrictive ventilatory defect with severe impairment in diffusion capacity consistent with his primary pulmonary oedema and pleural effusion. Subsequently, patient underwent uncomplicated right-sided thoracentesis with removal of 2 L of pleural fluid.

A repeat TOE was performed on day 8 showing significant reduction in his EF to 30% along with a severely increased LV cavity size. Thickened aortic valve (AV) leaflets with destruction of the right coronary cusp were evidenced. Echocardiography also demonstrated severe aortic insufficiency, severe tricuspid regurgitations and a dilated inferior vena cava. Considering the resultant valvular destruction by the excrescences on the AV, progressively worsening heart failure symptoms, and the lack of response to medical management, the decision was eventually made to proceed with an urgent AV replacement surgery.

Surgical management

On day 9 after admission, patient was boarded to the operation room for a surgical AV replacement in the setting of severe aortic regurgitation. A bioprosthetic AV (23 mm Carpentier-Edwards PERIMOUNT Magna Ease valve) was successfully implanted. Intraoperative course was complicated by coagulopathy and bleeding requiring treatment with packed red blood cell transfusion, vitamin K, factor VII, Desmopressin (DDAVP)and prothrombin complex concentrate. Postoperatively, patient was transferred to the cardiovascular intensive care unit (ICU) where he received routine ICU protocols for 5 days before transfer to the general floor.

Surgical specimen

Gross examination of the surgical specimen obtained from the AV showed a fibrotic cardiac valve with acute endocarditis vegetations. AV leaflets showed tan-yellow, irregularly thickened portions of the valve cusp, measuring 21×13×12 mm in aggregate, along with a fenestration measuring 7×7 mm. Tissue culture of the AV leaflet showed moderate WBCs but was negative for organisms on gram staining and demonstrated no growth after 3 days.

Outcome and follow-up

The surgical intervention was successful and postoperative treatment with intravenous penicillin was continued. Patient commenced significant improvement in his shortness of breath and lower limb oedema after the procedure. TOE performed 2 weeks after surgery showed a normally functioning bioprosthetic valve with no regurgitation of aortic prosthesis present (figure 5). EF was 46% and pulmonary artery pressure was normal at 29 mm Hg (compared with a preoperative 30% and 46 mm Hg, respectively). Table 1 represents a literature review summarising key findings and outcomes in identical cases of E. Rhusiopathiae endocarditis of the AV.

Figure 5.

Transoesophageal echocardiogram, performed 2 weeks following aortic valve (AV) replacement, demonstrating a well-seated and normally functioning bioprosthetic AV.

Table 1.

Literature review summarising key findings in Erysipelothrix Rhusiopathiae endocarditis of the aortic valve

ID	First author	Year	Age	Gender	Culture	Valves	Presentation	Medical treatment	Surgery	Outcome	Risk factor
1	W Schiffman	1956	55	M	Positive	AV only	Fever and myalgia	Intravenous penicillin + streptomycin	No	Alive a year later	Alcoholic + tuberculosis
2	JH Heggers	1974	37	M	Negative	AV	Fever, headache and chills	Intravenous penicillin	No	Expired day 2 of admission	Alcoholic
3	N Muirhead	1980	53	M	Positive	AV only	Night sweating, weight loss, polyarthralgia, fever	Intravenous benzopenicillin	No	Alive 6 months later	Farmer + chronic lymphocytic leukaemia
4	M Rocha	1989	51	M	Positive	AV only	Septicaemia + endocarditis	Intravenous penicillin G+ cefoxitin	AVR	Discharged alive at 8 weeks	None
5	KA Borchardt	1997	41	M	Positive	AV only	Fever, dyspnoea, oedema and skin rash	Intravenous penicillin	AVR	Alive 6 months later	Fisherman
6	S Nandish	1999	78	M	Positive	AV + MV	Acute heart failure	Intravenous penicillin G	AVR and MVR	Discharged alive at 6 weeks	Alcoholism + uncooked pork consumption
7	AL Artz	2001	46	M	Positive	AV only	Fever, night sweats, erythema multiforme	Intravenous amxocillin + intravenous clindamycin	AVR	Discharged alive at 6 weeks	Alcoholic + butcher
8	E Umana	2002	49	M	Positive	AV only	Pneumonia-like symptoms	Intravenous penicillin G + gentamycin	AVR	Discharged alive at 4 weeks	None
9	TW Boo	2003	37	M	Negative	AV only	Fever, night sweats and weight loss	Intravenous penicillin + gentamycin	AVR	Discharged alive	Alcoholic + farmer + lacerative wound on contact with pigs
10	SB Ko	2003	63	F	Positive	AV only	Fever + altered mental status	Intravenous penicillin + ceftriaxone	No	Discharged alive at 6 weeks	Fisherwoman + recent finger laceration at work
11	HJ Carson	2005	54	M	Positive	AV + MV	Septic shock, hypothermia, and cachexia		No	Expired on day of admission	None
12	T Miura	2012	42	F	Positive	AV Only	Fever + fatigue	Intravenous penicillin	AVR	Alive 6 months later	None
13	Dean Campbell	2013	51	M	Positive	AV only	Septicaemia + endocarditis + pulmonary oedema	Intravenous ceftriaxone	AVR	Alive 8 months later	Alcoholism + intravenous heroin use + homeless
14	P Hua	2015	65	M	Positive	AV + MV	Dyspnoea and palpitations. No fever.	Intravenous penicillin	AVR	Alive 2 years later	None
15	Limay vázquez	2015	40	M	Positive	AV only	Fever only	Intravenous penicillin G	AVR	Discharged alive at 6 weeks	Alcoholic, fishing, wounded by fish bone
16	JJ Nielsen	2017	59	M	Positive	AV only	Fever, diplopia and ataxia	Intravenous penicillin + gentamycin	AVR	Alive 1 year later	Fisherman + alcoholic

AV, aortic valve; AVR, aortic valve replacement/repair; MV, mitral valve; MVR, mitral valve replacement/repair.

Discussion

Infective endocarditis is a rare presentation for the pathogen—reported to occur in less than 1% of all E. Rhusiopathiae infections. It can present as both acute and subacute endocarditis. The bacilli exhibit a peculiar tropism to the AV.^{9 10} Nonetheless, E. Rhusiopathiae endocarditis has been associated with high mortality estimated to approach 40% in some reports.¹ Further, endocarditis linked to E. Rhusiopathiae tends to be highly virulent with about one-third of patients requiring valve replacement.^{1 11 12}

E. Rhusiopathiae is classically reported to be pan-susceptible to penicillin which was the case in our isolated bacteria. On the other hand, E. Rhusiopathiae is usually intrinsically resistant to aminoglycosides, trimethoprim–sulfamethoxazole and vancomycin.^{9 10} Susceptibility to other antibiotics, however, is variable in the literature. Hence, penicillin has traditionally been considered the treatment of choice. In the setting of infective endocarditis, however, it sounds like eradication of the bacterium with antimicrobial treatment alone might not be sufficient. Reviewing the literature, a significant proportion of patients with infective endocarditis due to E. Rhusiopathiae eventually required surgical replacement of the valve (classically AV); reflecting the virulent nature and destructive impact of the bacterium on valves. In our case, the patient required to have AV replacement in spite of the microbiological responsiveness to treatment with penicillin—as evidenced by repeatedly negative blood cultures. These observations should urge healthcare providers to anticipate and plan early for valvular surgery in similar settings.

The presented case represents a diagnostic dilemma given that the initial presentation was consistent with acute congestive heart failure in a patient with a considerable risk for coronary artery disease (ie, extensive smoking history). Further, the patient was lacking for any clue suggestive for an infectious aetiology for his presentation (ie, afebrile and without leukocytosis). Moreover, the atypical presentation (ie, absence of cutaneous manifestation and no evidence for sepsis) for this atypical organism adds to the complexity of the diagnostic process. Our patient, however, had several risk factors that have been linked to infections with E. Rhusiopathiae. These include presumed occupational exposure (ie, working in a barn), contact with animals (ie, specifically mice here) and chronic alcoholism.

Learning points.

• In conclusion, Erysipelothrix Rhusiopathiae should be considered in the differential diagnosis for Gram-positive bacilli bacteraemia and endocarditis.

• In the proper clinical setting, occupational exposure and contact with animals can be helpful clues to raise suspicion for this bacillus.

• The high mortality associated with the pathogen should urge for early identification and initiation of antimicrobial treatment; otherwise, outcomes can be devastating.