Case Report: Complex parapneumonic effusion and bacteremia secondary to Granulicatella adiacens in immunocompetent host

Introduction

Granulicatella adiacens is a member of the Granulicatella genus of the fastidious nutritionally variant group of the Gram-positive streptococci. The most common clinical syndromes associated with this organism are Endocarditis and Bacteremia, but cases of vertebral osteomyelitis and spontaneous bacterial peritonitis have also been reported^1,2. To the best of our knowledge, we are presenting the first case of complex parapneumonic effusion with bacteremia secondary to G. adiacens.

Case presentation

A 56 year old male with a history of seizure disorder presented to the Emergency Department with shortness of breath for three days. He also reported productive cough with yellow sputum, right sided chest pain, anorexia, night sweats, fatigue and fever for the same duration. The patient denied any hemoptysis, chills, rigors, leg swelling and recent travel, but had an episode of upper respiratory tract infection three months ago due to sick contact. The patient’s past surgery history was significant for subdural hematoma treated with frontal craniotomy 20 years ago. In addition, the patient used to take dilantin for his seizure disorder, but stopped taking this medication a long time ago. The patient’s mother had a history of breast cancer. Th patient is a smoker for 38 years, and smoked half a pack of cigarettes a day. He is a chronic alcoholic and had drunk 3–4 beers every day for many years, but denies any illicit drug use. He lives with his family.

On admission, he was febrile to 100.6 F, tachycardic to 150 bpm, hypertensive to 157/93 and saturating at 91% in room air. In the general examination, the patient was diaphoretic. Respiratory examination revealed mild tachypnea with dullness to percussion on right hemithorax, decreased breath sounds in the same area and crackles but no wheezing. Other than the regular tachycardia, the remainder of the physical examination was unremarkable. Initial labs showed leukocytosis of 36.5 K/uL (normal range, 4.5–11k/uL), hemoglobin of 16.7 g/dl (13.5–17.5 g/dl), platelet of 415 K/uL (130–400 k/uL), blood urea nitrogen of 9mg/dl (6–20mg/dl), creatinine of 0.9mg/dl (0.5–0.90 mg/dl), D-Dimer of 492 ng/ml (<250 ng/ml), lactic acid of 1.8 mmol/L (0.5–2.2 mmol/L), BNP (Brain Natriuretic Peptide) of 10 pg/ml (<100 pg/ml). Other tests, including rapid influenza, urine legionella antigen, urine streptococcus pneumoniae antigen, troponin and HIV were negative. A chest X-ray showed consolidation on the right side (Figure 1).

Figure 1. Chest X-ray showing right-sided consolidation.

Computerized tomography (CT) angiography of the chest was negative for pulmonary embolism but showed large volume complex parapneumonic effusion on the right side (Figure 2).

Figure 2. CT scan on admission showing right-sided effusion.

The patient was admitted to the Intensive Care Unit for acute hypoxic respiratory failure and sepsis secondary to right-sided multifocal pneumonia with complex parapneumonic effusion. A chest tube was placed on day 1 with drainage of almost 2.2 L of serosanguinous fluid. Tissue plasminogen activator (10mg every 12 hourly) and deoxyribonuclease therapy (5mg every 12hrly) were given through the chest tube for a total of three days. Pleural fluid was exudative with polymorphonuclear cells. Pleural fluid cultures including mycobacterial cultures, fungal cultures and parasitic exams were negative. Blood culture from day 1 grew G. adiacens in anaerobic bottles sensitive to Ceftriaxone, Levofloxacin, and Vancomycin. Transesophageal echocardiogram (on day 8) did not show any vegetation.

On day 1 of hospitalization, the patient was started on vancomycin (1250mg every 12 hourly; goal trough of 15–20 mcg/ml), Piperacillin/Tazobactam (3.375 gm every 8 hourly) and azithromycin (500mg daily empirically), which was continued until day 5. On day 6, antibiotics were switched to Ceftriaxone (2 gram IV every 24 hourly), Ampicillin (2 gram IV every 4 hourly), Gentamicin (80mg IV every 8 hourly; goal trough <1 mcg/ml and goal peak 3–4 mcg/ml) and Metronidazole (500mg IV every 8 hourly) for complex parapneumonic effusion with bacteremia secondary to G. adiacens, as per recommendations from the Infectious Disease team, which was continued up to day 21.

The patient started feeling better with resolution of his fever, cough, chest pain, fatigue and anorexia on day 7. By day 10 his shortness of breath resolved, and he was back to his baseline. His leukocytosis improved from 35.6 k/ul on day 1 to 16.7 k/ul on day 9 and resolved to 9.14 k/ uL on day 17. Follow up CT scan chest on day 15 showed small loculated effusion, which had improved from admission (Figure 3).

Figure 3. Post-drainage CT showing improvement in right-sided effusion.

The CT surgery team evaluated the patient and deferred video-assisted thoracoscopic surgery decortication. On day 21, the patient left against the medical advice. The patient completed one more week of Ceftriaxone (2 gram every 24 hourly) and Metronidazole (500mg every 8 hourly) as an outpatient with sustained remission of symptoms on follow-up. A follow-up CT scan of the chest two months later showed a near complete resolution of the residual effusion (Figure 4).

Figure 4. Follow-up CT scan chest after two months showing near complete resolution of effusion.

Discussion

A new type of Viridans group Streptococci was discovered in 1961 by Frenkle and Hirsch. This was termed as NVS (Nutritionally Variant Streptococci) and the discovery was based on prolonged incubation period, characteristic growth requirement, variable gram stain findings and satellite promoting phenomenon around cologies of other bacteria . The growth of NVS is not supported by routinely used blood culture media unless they are supplemented with pyridoxal. That is why NVS are usually considered to be very fastidious³. Identification of Granulicatella isolates are performed by either biochemical testing such as API Strep or bioMerieux or molecular confirmation. Identification was delayed in several cases, as isolates were thought to be poorly growing streptococci before consideration of pyridoxal dependence⁴. Though it is a normal commensal in the oral cavity, the spectrum of infections with Granulicatella species seems to be expanding, and infections are associated with significant morbidity and mortality. The clinical course is more severe than Viridans streptococci. A high index of suspicion and vigilance is needed because of its fastidious nature, slow growth rate, difficulty in isolation on culture media, and multiple antibiotic resistance. Microbial communities that have any kind of impact on tumor progression and microorganisms associated with tumors have been defined as oncobiome. The detailed analysis of microbiome in lung cancer patients documents the presence of G. adiacens, which is not a normal commensal in healthy lungs and further research into this area is warranted⁵.

There are reports of G. adiacens as a rare cause of neonatal pneumonia^6,7. We could not find any reported cases of pneumonia caused by G. adiacens in immunocompetent adults; however, it has been reported in patients suffering from pulmonary tuberculosis and concurrent HIV infection⁸. To the best of our knowledge, our case could be the first case of a parapneumonic effusion caused by infection with G. adiacens. Patients at risk of developing Granulicatella species infections are usually immunocompromised in contrast to our patient who was immunocompetent^2,9.

Both G. adiacens (susceptibility rates of 0–63% to ceftriaxone, 81% to amoxicillin, 55–67% to penicillin and 96% to meropenem) and G. elegans (susceptibility rates of 0% to cefuroxime, 100% to penicillin and 33% to ceftriaxone) were reported to have the resistance to β-lactam antibiotics. Resistance was also reported to tetracycline, clindamycin, ciprofloxacin, erythromycin, but not to rifampicin or vancomycin^10,11. The infection is usually treated with the antibiotic regimen used for enterococcal endocarditis usually consisting of a combination of ampicillin or penicillin plus gentamicin. Ceftriaxone plus gentamicin or vancomycin monotherapy are reasonable alternatives¹².

Conclusions

Granulicatella adiacens is a fastidious organism that has the potential to infect multiple systems in both immunocompetent and immunocompromised patients.

Given our case of G. adiacens complex parapneumonic effusion/pneumonia and bacteremia in an otherwise immunocompetent adult and the difficulty to diagnose, a high index of suspicion is required to catch and treat it early on.

Consent

Written informed consent was obtained from the patient for the publication of this case report and any associated images.

Data availability

All data underlying the results are available as part of the article and no additional source data are required.