CT-A/P-axial-view-demonstrating-multiple,-hypoattenuating,-ill-defined-cystic-lesions-in-the-liver-(red-arrows)-with-peripheral-enhancement-and-internal-septation

Multiple hepatic abscesses secondary to Streptococcus anginosus infection: about a case and review of the literature

Pyogenic liver abscess (PLA) is a highly fatal condition, and the leading cause of death is septic shock [1]. The early use of imaging techniques like computed tomography (CT) and magnetic resonance imaging (MRI) helps in the rapid diagnosis of the disease and a better prognosis. The challenge still remains to find the source of the infection causing liver abscess. Biliary tract disorders, systemic infections (infective endocarditis, pyelonephritis) and colon disorders are the main sources and should be adequately investigated. [2].

We report a rare case of an immunocompetent woman with multiple liver abscesses caused by Streptococcus anginosus, which was successfully managed with antibiotics.

A 73-year-old woman with well-controlled type II diabetes, hyperlipidemia, and osteoporosis presented to the emergency department with complaints of fever associated with chills, watery diarrhea (4-5 episodes/day) and diffuse abdominal discomfort for 2-3 days. She denied having myalgia, nausea/vomiting, yellowish discoloration of the eyes, burning urination, chest pain, air hunger, recent travel or eating out, and recent instruments. The patient had a history of appendectomy in childhood and ectopic pregnancy surgery in the distant past.

On physical examination, the patient had a temperature of 102.7 F (oral), a heart rate of 137/min, a respiratory rate of 20/min, and her blood pressure was measured at 96/58 mm Hg. L Abdomen was soft with slight tenderness in right upper quadrant with active bowel sounds. Murphy’s sign was negative with no significant defense or rebound sensitivity. The remainder of the examination was unremarkable. Initial labs included a white blood cell (WBC) count of 17.3 K/uL with 78% neutrophils, hemoglobin of 11.8 g/dL, platelets of 214 K/uL, hemoglobin A1c of 6.5 %, blood urea nitrogen (BUN)/creatinine 14/1.08 g/dL, alanine aminotransferase/aspartate aminotransferase (ALT/AST) 93/73 U/L, alkaline phosphatase (ALP)/total bilirubin (T Bili ) 160/0.9 mg/dL and C-reactive protein (CRP) 249 mg/L Her urinalysis showed WBC >100/hpf, RBCs 0-5, nitrite negative, leukocyte esterase large, hyaline cast 0 -5 and rare bacteria. The coagulation profile was within normal limits. Hepatitis panel, gastrointestinal polymerase chain reaction panel, and stool screening for ova/parasites were not significant. Urine and blood cultures were sent, and the patient was empirically started on ceftriaxone and metronidazole.

An abdominal ultrasound was performed, which suggested an echogenic lesion in the gallbladder wall measuring up to 0.3 cm, most likely a polyp. No hepatic mass was demonstrated. However, computed tomography of the abdomen/pelvis showed multiple hypo-attenuating and ill-defined lesions in the right hepatic lobes, the largest lesion measuring up to 2.9 cm with a small amount of peripheral enhancement and a septum. internal (Figure 1). These results were suggestive of early abscess formation in the liver compared to metastases.

CT-A/P-axial-view-showing-poor-defined-hypoattenuating-multiple-cystic-lesions-in-the-liver-(red-arrows)-with-peripheral-enhancement-and-internal-septation

MRI of the liver revealed multiple hepatic abscesses with dilation of the communicating intrahepatic bile duct, hyper-enhancement of the gallbladder wall, and a relatively attenuated signal filling the gallbladder/biliary tree. MRCP confirmed these results and was consistent with acute cholangitis and associated hepatic microabscesses (Figure 2).

MRCP-showing-multiple-hepatic-abscesses-(red-arrows)-with-intrahepatic-connecting-biliary-duct-dilation,-hyper-enhancement-of-the-gallbladder-wall-and -an-attenuated-signal-fill-the-gallbladder/biliary-tree

A transthoracic echocardiogram revealed an ejection fraction of 55-60% and normal valvular structures without any vegetation. Three days later, the alpha hemolytic streptococcus Streptococcus anginosus (susceptible to ceftriaxone, clindamycin, erythromycin, levofloxacin, penicillin, vancomycin) was isolated from the blood culture, while the blood culture was negative. Repeat blood cultures obtained on the third and fourth days of admission were negative.

During hospitalization, ceftriaxone and metronidazole were continued. Her clinical condition continued to improve and there was a noticeable improvement in laboratory parameters during her hospital stay. The patient was discharged on oral antibiotic therapy (levofloxacin and metronidazole) after seven days of hospital treatment with outpatient follow-up. She was asymptomatic with unremarkable lab values ​​at her follow-up visit with the infectious disease specialist three weeks later (Table 1). She was then switched to oral clindamycin for six weeks.

Laboratory test Initial value 3 week value Reference range
UK 17.3K/uL 5.7K/uL 4.5-10.9K/uL
ALT 93 U/L 14 U/L 0-31 U/L
AST 73 U/L 19 U/L 10-35 U/L
ALP 160 U/L 113 U/L 25-125 U/L
T-Bili 0.9mg/dL 0.3mg/dL 0.0-1.2mg/dL
HAIR BUN 14mg/dL 11mg/dL 8-23mg/dL
Creatinine 1.08g/dL 0.9mg/dL 0.5-0.9mg/dL
PCR 249mg/L 1.2mg/L 1-4mg/L

In a six-week follow-up, the new CT scan showed complete resolution of all liver lesions except for one small (5.5 mm) hypoattenuating lesion. This lesion also decreased in size from the previous finding of 2.9 cm (Figure 3). The patient was referred for a colonoscopy to exclude colon cancer.

Repeat-CT-A/P-showing-almost-complete-resolution-of-all-liver-lesions-at-approximately-six-weeks

Liver abscesses are rare diseases, with an approximate annual incidence of 2.3 per 100,000 people [3]and the etiological agent is usually polymicrobial [4]. Common agents include enteric gram-negative bacilli (Escherichia coli, Klebsiella pneumonia), Streptococcus milleri group (SMG), and anaerobes. Streptococcus species has been identified as the culprit in 29.5% of pyogenic liver abscesses [5]. Streptococcus anginosus belongs to the “Streptococcus milleri group” of bacteria, which includes two other different species: Streptococcus intermedius and Streptococcus constellatus [6]. These bacteria reside as normal flora in the respiratory, gastrointestinal, and urogenital tracts; and have the potential for abscess formation due to their multiple virulence factors, including polysaccharide capsules, exotoxins, and hydrolytic enzymes like hyaluronidase and DNase [7].

Liver abscesses usually arise by one of four routes: infection of the abdomen spreading through the portal vein, direct spread from a biliary source, hematogenous spread from any systemic infection or penetrating wound [8]. Given the MRI finding of a hepatic abscess communicating with intrahepatic bile duct dilation, the source was probably biliary in our patient. Although the MRI/MRCP was concerning for biliary cholangitis, it lacked clinical criteria for cholangitis (absence of fever and jaundice). Bile duct disorders are most commonly associated with liver abscesses caused by GMS [9].

Our patient’s presentation matched the common clinical features seen in pyogenic liver abscess (fever/chills, nausea/vomiting, right upper quadrant pain, and elevated liver enzymes); however, these results are not diagnostic of PLA [10]. Therefore, imaging modalities play a crucial role in establishing the diagnosis. Also, isolation of organisms from a blood culture or abscess is equally important to guide antibiotic regimen.

Streptococcus anginosus bacteremia would require further evaluation for deep infection, including endocarditis and pyelonephritis [11]. Treatment usually involves two weeks of antibiotics if it is uncomplicated bacteremia. However, a prolonged duration of treatment of approximately 6 weeks is necessary in cases of abscess as in our patient. Drainage, percutaneous or surgical, is recommended in case of significant hepatic abscess (> 5 cm) [12].

In conclusion, liver abscess is a rare condition that manifests with common complaints like abdominal pain and fever. A high degree of suspicion with appropriate imaging can aid in diagnosis. Ultrasound may not be sensitive enough to detect these lesions as seen in our patient. Additional imaging with CT A/P and MRI/MRCP is needed for confirmation. As APL is associated with significant mortality, prompt management with appropriate antibiotics and/or aspiration/drainage is essential for best results.



Multiple hepatic abscesses secondary to Streptococcus anginosus infection: about a case and review of the literature

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