A 62-Year-Old Man With Tricuspid Valve Endocarditis, Bacteremia, and Septic Pulmonary Embolism Following Long-Needle Acupuncture

Introduction

Right-sided infective endocarditis (RIE), which is significantly less common than left-sided infective endocarditis (IE), occurs predominantly in intravenous (IV) drug users with normal valves [1]. Rarely, RIE originates from metastatic infections introduced through nonsterile skin puncture [2]. Acupuncture, widely practiced as an alternative medical therapy, is generally considered safe. However, when performed without strict infection control, it can lead to complications, such as local cellulitis, soft tissue abscesses, and even bloodstream infections [3]. In a small cohort of 36 patients with valvular heart disease, no case of endocarditis was detected over a 10-year period. Thus, brief acupuncture was proven safe [4]. However, a few cases of IE secondary to acupuncture have been reported, mainly involving left-sided prosthetic or rheumatic cardiac valves [5–8]. No cases of IE have occurred in immunocompetent patients with normal native heart valves and intact skin barrier.

Staphylococcus aureus is a gram-positive bacteria commonly found on human skin. Compared with its methicillin-resistant counterpart MRSA, methicillin-susceptible strains are common in community-acquired infection. More often, methicillin-susceptible S. aureus (MSSA) can cause serious illness, including life-threatening IE, particularly when introduced via invasive procedures such as acupuncture. In the literature, MSSA-related RIE is typically associated with rapid clearance of bacteremia and favorable clinical outcomes, with relatively few septic complications [9].

Here, we present a rare case of a 62-year-old man with MSSA tricuspid valve endocarditis, bacteremia, and septic pulmonary embolism following long-needle acupuncture. The patient exhibited persistent bacteremia and new-onset tricuspid valve endocarditis following initial antimicrobial therapy with cefazolin. After switching to daptomycin monotherapy, emerging septic pulmonary embolism highlighted the limitation of drug distribution and penetration in pulmonary tissue. A combination antibiotic regimen was ultimately successful as salvage therapy. This case highlights the need for heightened clinical suspicion, timely diagnosis, and appropriate antibiotic strategies in managing MSSA RIE with persistent bacteremia, particularly in non-IV drug users without underlying valvular abnormalities.

Case Report

A 62-year-old man presented to the emergency department with a 3-day history of fever, anorexia, fatigue, and aggravated back pain. Three days prior to symptoms onset, he had received 3 sessions of acupuncture to the lower back using 6-cm-long needles for suspected lumbar disc herniation (see Figure 1 for the timeline of patient’s symptoms and antibacterial treatment). On admission, his vital signs were as follows: body temperature 39.2°C, heart rate 90 beats/min, respiratory rate 20 breaths/min, and blood pressure 136/85 mmHg. Laboratory test results showed an elevated white blood cell count of 16.62×109/L, with 93.5% neutrophils, and a platelet count of 43×109/L, indicating thrombocytopenia. The serum procalcitonin level was significantly elevated at 2.62 pg/mL. Magnetic resonance imaging (MRI) of the lumbar spine revealed bilateral psoas swelling and L5/S1 lumbar disc herniation, located along the needle pathway from the acupuncture procedure. Empirical IV ceftriaxone and vancomycin were initiated for suspected infection. Pre-antibiotic blood cultures (2 sets) were obtained on admission. A follow-up 2 sets were drawn 24 hours later.

On hospital day 3, the patient developed hypotension, dyspnea, and dulled consciousness. Arterial blood gas analysis indicated hypercapnic respiratory failure and hyperlacticemia. He required invasive mechanical ventilation and fluid resuscitation for septic shock. On that day, 3 of 4 sets of blood cultures yielded S. aureus.

A fluctuant, swollen lesion was noted on his right elbow during routine skin monitoring, which was not present upon admission. Incision and drainage revealed a superficial fascia abscess. Gram stain and culture of purulent material obtained from aspiration were performed. S. aureus was isolated from solid and liquid culture media. Vancomycin was continued until susceptibility testing confirmed MSSA on hospital day 7, both in blood and purulent material, at which point cefazolin was started according to the current recommendation. By hospital day 8, the patient was successfully weaned off mechanical ventilation, owing to hemodynamic stabilization and improved oxygenation. Blood cultures drawn on hospital day 9 showed no growth and converted to negative.

On hospital day 10, the patient experienced a recurrence of fever, dyspnea, hypotension, and sinus tachycardia. Physical examination revealed jugular venous distention and a new tricuspid regurgitation murmur. Transthoracic echocardiography identified a ribbon-like vegetation (23×6 mm) on the septal leaflet of the tricuspid valve, protruding into the right ventricle with each atrial systole. There was moderate tricuspid regurgitation and right atrial enlargement (Figure 2A). Severe pericardial effusion was at a depth of 22 mm along the diaphragmatic surface of the heart (Figure 2B). Analysis of the pericardial fluid revealed a hemorrhagic exudate, with a white blood cell count of 15–20 per high-power field, glucose level of 2.94 mmol/L (concurrent blood glucose: 8.5 mmol/L), and lactate dehydrogenase level of 2115 U/L. The Rivalta test was positive, supporting a mucin-rich exudative effusion. These findings were inconsistent with heart failure or autoimmune disease. Two repeat sets of blood cultures during a subsequent febrile episode again returned positive with MSSA. The sterile pericardial fluid culture from the aspirate was negative.

Concurrently, the patient had persistent lumbar pain radiating to the hips and legs. Repeat MRI revealed disseminated abscesses involving the bilateral psoas, iliopsoas, and erector spinae muscles, along with destruction of the L3/L4 vertebrae and intervertebral disc (Figure 3). Ultrasound-guided percutaneous drainage of the psoas abscess was performed. Gram stain of the pus showed numerous gram-positive cocci. The purulent aspirate was processed for routine sterile body fluid culture. MSSA was again isolated, consistent with prior blood culture results, and remained sensitive to cefazolin. However, given the clinical failure of cefazolin and concern for emerging resistance, daptomycin was initiated.

After 6 days of daptomycin, vegetation size was significantly reduced, and the pericardial drainage tube was removed. However, routine bedside chest radiography revealed worsening pulmonary findings. Chest CT showed wedge-shaped, subpleural nodules with a cavity in the left upper lobe (Figure 4), consistent with septic pulmonary embolism. Cultures from intramuscular sites again confirmed MSSA, while repeat blood cultures were negative. To improve antimicrobial coverage, cefazolin was reintroduced in combination with daptomycin to ensure adequate drug penetration into lung tissue, muscle, and vertebral structures. After 5 days, daptomycin was discontinued following negative blood cultures (2 sets, 4 bottles). Cefazolin monotherapy was continued for 6 weeks until the valvular vegetation, psoas abscesses, and vertebral infections resolved.

Follow-up transthoracic echocardiography showed preserved valve function and no residual vegetations. Serial blood cultures remained negative. At 3- and 6-month follow-up, the patient recovered, with no signs of recurrence or complications.

Discussion

Infection is among the most significant adverse events associated with acupuncture [3]. While skin and soft tissue infections at needle puncture sites are the most commonly reported complications, inadequate drainage of localized abscesses can result in bacteremia and metastatic infections. In a small cohort of patients with valvular heart disease, 4 of 36 (11.1%) had prosthetic valves at presentation; however, no cases of endocarditis were detected over a 10-year follow-up period [4]. Brief acupuncture therapy is considered relatively safe in patients with valvular heart disease. However, prior case reports have described acupuncture-associated IE, typically involving left-sided prosthetic or rheumatic cardiac valves [5–8]. Although a few cases have documented native-valve left-sided IE linked to acupuncture, they largely occurred in immunocompromised individuals or those with impaired skin barriers [10,11]. Only 1 previous report described a healthy male patient who developed native aortic valve MSSA endocarditis, attributed to the high virulence and invasiveness of S. aureus [12].

In our case, acupuncture-induced RIE appears to be exceptionally rare. The only previously published case involved an adolescent patient with eczema-induced skin barrier disruption [10]. In contrast, our patient was immunocompetent with normal heart valves and developed a rapidly progressive infection that included cutaneous and deep tissue infections, persistent bacteremia, large tricuspid valve vegetation, septic pulmonary embolism, and purulent pericarditis – all within 2 weeks of acupuncture treatment. The isolation of MSSA from blood and pus samples supports the likely hematogenous spread from the acupuncture site. While RIE is typically associated with IV drug users, other at-risk populations include patients with IV devices (eg, pacemakers or central venous catheter) and those with congenital heart disease [1]. Although RIE generally carries a better prognosis than left-sided IE, the clinical presentation and management, particularly in non-IV drug users, remain less well defined. This case illustrates the challenges of treating acupuncture-induced RIE, which is often complicated by high-grade bacteremia and delayed diagnosis, due to its rarity in immunocompetent individuals.

MSSA remains the leading cause of RIE. Evidence consistently supports the use of β-lactam antibiotics over vancomycin for MSSA bacteremia, due to less clinical failure, lower mortality, and fewer adverse effects, particularly nephrotoxicity [13]. Moreover, recent studies have shown increased tolerability and perhaps better outcomes in patients receiving cefazolin, compared with classical antistaphylococcal β-lactams, such as oxacillin and nafcillin [14,15]. However, new-onset RIE and metastatic abscesses in the present case indicated our patient did not respond adequately to initial cefazolin monotherapy. We were concerned about the cefazolin inoculum effect rather than drug resistance, which was confirmed by repeated susceptibility results. It has been reported that some strains of MSSA that produce β-lactamases are correlated with an in vitro increase in cefazolin minimum inhibitory concentrations when the bacterial inoculum is large. This reduced susceptibility may be particularly relevant in IE, where vegetations have very high bacterial densities. The cefazolin inoculum effect is associated with increased mortality in MSSA IE in the first month [16]. However, there is insufficient evidence that cefazolin is at a disadvantage in MSSA IE as first-line therapy. Due to its potential role in clinical failure, especially in complex infections with high bacterial burdens, the cefazolin inoculum effect should not be overlooked.

Daptomycin, approved for the treatment of complicated skin and soft tissue infections, MSSA bacteremia, and RIE [17], was used as salvage therapy. However, its activity is inhibited by pulmonary surfactant, limiting its efficacy in pneumonia. This pharmacokinetic limitation may explain the progression of septic pulmonary embolism in our patient despite temporary bacteremia clearance [18]. According to current recommendations, patients with MSSA infection and adequate β-lactam susceptibility should ideally receive antistaphylococcal β-lactams over daptomycin. Although, in a small simple size study including 7 patients with complicated MSSA bacteremia, including 4 with endocarditis, the addition of β-lactams to daptomycin as a salvage regimen elicited a rapid clearance of bacteremia [19], adjunctive daptomycin has not been shown to significantly improve outcomes or reduce the duration of bacteremia in MSSA bacteremia [20]. In our case, daptomycin was discontinued, and cefazolin was reintroduced to optimize tissue penetration, especially in the lungs, muscles, and vertebrae, and to reduce overall treatment cost. The patient responded well to this adjusted regimen, completing a 6-week course of cefazolin monotherapy with full resolution of infection.

Future studies proving the clinical significance of novel combination strategies for persistent MSSA infection are therefore warranted. Ertapenem combination therapy has been demonstrated to have a synergistic effect with cefazolin, presenting a viable salvage option [21]. Considering local resistance patterns of cefazolin or antistaphylococcal penicillins, ceftaroline, fosfomycin, rifampin, and gentamicin are explored as candidates for combination therapy in persistent MSSA infection. Efficacy vary with each combination, adverse events, and duration of therapy remains diverse across studies in the absence of well-established guidelines.

Conclusions

Infective endocarditis involving native valves following acupuncture is exceedingly rare, particularly in immunocompetent individuals without predisposing cardiac conditions. This is the first reported case of acupuncture-induced RIE complicated by septic pulmonary embolism and purulent pericarditis. Acupuncture can lead to severe infections, including RIE, in individuals without traditional risk factors. This report illustrates the importance of alertness, diagnosis, and antibiotic options in MSSA bacteremia and RIE caused by acupuncture. Antistaphylococcal β-lactam–based combination therapy should be initiated when standard first-line antibiotics fail to resolve persistent MSSA bacteremia or hematogenous spread.