Streptococcus Pseudoporcinus and Cardiac Implantable Electronic Device: Do We Need To Worry?? A Case Report.

CIED: Cardiac Implantable Electronic Device 

IE: Infective Endocarditis 

CDRIE: Infective Endocarditis related to Cardiac Device 

ECG: Electrocardiography 

AVB: Atrioventricular block 

RBBB: Right bundle branch block 

TTE: Transthoracic echocardiogram

TEE: Transesophageal echocardiogram

An 81-year-old gentleman presented with a 2-day history of fevers and chills. On admission, he was febrile, with a body temperature of 37.6°C, tachypneic (respiratory rate: 30 breaths/minute) with 97% oxygen saturation on room air, and hemodynamically stable. 

ECG showed sinus rhythm at 65 beats/minute, 1st degree AVB and RBBB. His physical examination was unremarkable, except for mild, diffuse abdominal tenderness on palpation. 

White blood cells count was 11,700 cells/μl (normal range: 3.8-10.5 cells/μl) with 73.4% neutrophils, hemoglobin was 9.4g/dl (14-18 g/dl), platelets were 96,000 K/μl (150-450), erythrocyte sediment rate was 107 mm/hr and C-reactive protein was 8.66 mg/dl ( < 0.5). Creatinine was 1.91 mg/dl (0.72-1.18mg/dl) and urea 66 mg/dl (17- 43 mg/dl). Urinalysis demonstrated proteinuria and increased RBCs.

His medical history included hypertension, hyperlipidemia, cholecystectomy, past exposure to asbestos, Hodgkin lymphoma, portal hypertension with hepato/splenomegaly, angiectasias, colon polyps, and a recent 2-months-old  pacemaker implantation due to 3rd degree of AVB. 

Medications included ASA 100mg, bisoprolol 2,5mg, ramipril 5mg and acetaminophen as needed.

His presentation was suspicious for abdominal infection. Non-infectious syndromes such as inflammatory bowel diseases, ischemic colitis, and malignancies can also present with fever and diffuse abdominal pain, though.

His chest and abdomen radiography were unremarkable. Ultra-sound and Computed tomography of the abdomen did not reveal relevant abnormal findings. Blood cultures were obtained while the patient was febrile and empiric antibiotic treatment was initiated. 

Blood cultures were soon reported to contain Gram-positive cocci in chains. 

A TTE demonstrated a normal ejection fraction with mild aortic stenosis and regurgitation and no evidence of valvular or lead vegetation. A TEE did not reveal signs of cardiac infection either (Figure 1).

 Figure 1: Tranesophageal Echocardiogram. Transesophageal echocardiogram did not reveal any vegetation on valves or pacer’s leads. 

Vascular and immunological phenomena were investigated and fundoscopy revealed a Roth spot in the left eye. 

Due to his recent cardiac device implantation, a radiolabelled leucocyte scintigraphy was performed, which was positive for lead infection (Figure 2).

 Figure 2: Radiolabelled Leucocyte Scintigraphy. 99mTc-HMPAO-WBC scintigraphy revealed the presence of CIED-associated infection. 

Streptococcus pseudoporcinus was later identified in three separate blood cultures.

According to the existing guidelines, our patient met the modified Duke’s criteria for definitive endocarditis, one major (endocardial involvement) and three minor criteria (fever, Roth spot, and positive blood cultures with an organism not typically associated with endocarditis). The patient received 2gr intravenous ceftriaxone daily in accordance with the antimicrobial susceptibility testing. 

Repeat blood cultures remained negative, and complete hardware removal (device and transvenous lead extraction) was performed after a prolonged (4-week) antibiotic therapy. Subsequent blood cultures along with hardware cultures were negative. 

Optimal timing for reimplatantion of a new cardiac device was under consideration since there is a lack of experience regarding appropriate management of such infections. During his hospitalization, he experienced a new unprovoked episode of symptomatic 3rd degree AVB that was initially treated with isoproterenol. 

Eventually, device reimplatantion was performed after 20days of hardware free interval and after 1-month antibiotic therapy completion.

Streptococcus pseudoporcinus is a β-hemolytic Streptococcus first isolated from female genito-urinary tract in 2006; it can be CAMP- and Lancefield group B-positive and therefore can be misidentified as Streptococcus agalactiae. However S. agalactiae has a narrow zone of beta-hemolysis, is hippurate hydrolysis positive, is bile esculin hydrolysis negative, and does not produce acid from mannitol or sorbitol, unlike S. pseudoporcinus [1]. 

It was initially considered a colonizer of the female genital tract and cases of infection in men were associated with sexual activity [1-3]. 

First recordings demonstrated S.pseudoporcinus as an emerging pathogen for adverse maternal or neonatal outcomes in pregnancy [3-4]. Additionally, it has been reported as the virulent factor of soft tissue infections [1,5,15] or for more invasive infections, for instance bacteremia/infective endocarditis [6-9,13,15] and peritonitis [9]. In fact, 5 cases of S. pseudoporcinus related endocarditis have been identified through a thorough literature review [5-8], all involving native valves. No cardiac or other prosthetic device infection has been reported in the existing literature until now (Table 1). 

Table 1: Review of cases in the literature. 

Given the great similarities with Group B Streptococcus (Streptococcus agalactiae) [1] one could suppose a similar epidemiological and clinical behavior of both. Thus, they could represent an important cause of invasive infections in high-risk populations, especially in pregnant women, neonates, and the elderly and in individuals with underlying medical conditions such as diabetes, cirrhosis and cancer. 

Although Streptococcus species are commonly associated with endocarditis, this is the first known report of Streptococcus pseudoporcinus causing infective endocarditis related to cardiac device. 

S. pseudoporcinus can been isolated from human rectum, upper respiratory and genital tracts [3,5]. The definitive source of our patient’s S. pseudoporcinus is unclear. We postulate that it may have originated via gastrointestinal colonization and subsequent bacteremia due to his known angiectasias and splenomegaly. 

Last but not least, according to ESC guidelines, clinical presentation of CDRIE is frequently ambiguous and echocardiography and blood cultures are the cornerstones of diagnosis. A normal TTE does not rule out CDRIE and high suspicion is needed in the presence of unexplained fever in a patient with a CIED, whereas additive tools may be needed, such as radiolabelled leucocyte scintigraphy and 18F-FDG PET/CT scanning [10].

His postoperative course was uneventful. A 3-month overall antibiotic therapy was completed without any adverse concerns.

This is the first reported case of Streptococcus pseudoporcinus causing Infective Endocarditis related to Cardiac Device. 

Knowledge is limited regarding these recently differentiated novel species, and thus, reporting of previously unknown S.pseudoporcinus infection manifestations is of utmost importance. Accordingly, the present report extends current knowledge regarding the ability of S.pseudoporcinus to infect prosthetic materials and will, hopefully, raise the level of suspicion of cardiac or other prosthetic device infection in patients with persistent bacteremia. Moreover, given the lack of relevant experience and the successful outcome of the applied management course, this case could be used as a management/treatment guide, until consensus for such cases has been reached.

1. To recognize Infective Endocarditis related to Cardiac Device and to raise the level of suspicion for IE in patients with a CIED and unexplained fever. 

2. To understand that normal echographic examination does not rule out CDRIE and additive tools may be needed (radiolabelled leucocyte scintigraphy, 18F-FDG PET/CT scanning). 

3. To discuss how bacteremia by an uncommon bacterium, Streptococcus pseudoporcinus can cause Infective Endocarditis related to Cardiac Device.

The authors have nothing to disclose.

No funding.

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