Splenic abscess: Plasmodium vivax with secondary Escherichia coli infection

Introduction

Splenic abscess should always be given special consideration especially when it develops in an immunocompromised patient. Its incidence is in the range of 0.14–0.7% in autopsy studies and its mortality rate is in the range of 4.9–16.7%.^1,2 We found only one other case report of malaria with secondary bacterial infection in the literature. ³ We are adding another case to literature.

Case Report

A 40-year-old diabetic man presented with a history of fever with chills and rigors for the last 9 days, associated with a dragging sensation and pain over the left side of abdomen for the last 6 days. There was no history of alcohol intake. He was haemodynamically stable. A moderate tender splenomegaly was present on examination.

Investigations at the time of presentation showed a haemoglobin level of 6.8 g/dL, a total leukocyte of 3.5 × 10⁹/L, a platelet count of 65 × 10⁹/L. The peripheral blood smear and malaria antigen by card test was positive for Plasmodium vivax (P. vivax). The HbA1c was 7.2, blood urea 42 mg/dl and serum cretanine 1.3 mg/dl. HIV, HBsAg, anti-HCV, Widal test, and blood and urine cultures were all negative. The patient was commenced on antimalarials, but the fever did not subside. In view of the persistent fever, repeat investigations were carried out; both blood and urine culture revealed a growth of Escheria coli (E. coli). An abdominal ultrasound (US) scan demonstrated a large fluid-filled cavity within the spleen, suggestive of a splenic abscess. This was confirmed by a computed tomography (CT) scan which demonstrated in addition a left sided pleural effusion (Figures 1 and 2). CT-guided aspiration of the splenic abscess was performed, and a growth of E. coli was found on culture. The tuberculosis polymerase chain reaction (TB PCR) carried out on the purulent fluid was negative. Amikacin was started and a catheter drain was inserted; approximately 1 L of pus was removed. A repeat pus culture after 7 days was sterile and the catheter was removed on the following day, whereupon the patient was discharged. OPEN IN VIEWER

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Figure 2.

CECT abdomen showed splenic abscess.

Discussion

The incidence of splenic abscess is very low; it is in the range of 0.14–0.7% in autopsy studies. ¹ The mortality rate is in the range of 4.9–16.7% and is related to late therapeutic intervention; consequently an early diagnosis and appropriate aggressive treatment are mandatory. ² Splenomegaly is seen in 50–80% of malaria patients. Normally splenic enlargement is asymptomatic, but if a splenic infarct, torsion, rupture or abscess develop, these may prove fatal. A splenic abscess develops most commonly due to bacterial endocarditis, but may arise secondarily to trauma with hematoma formation, or in infarction due to a sickle cell or leukaemic crisis. Splenic abscess is more frequently found in immunocompromised patients. ³

Although US is non-invasive, cost-effective and readily available, it is operator-dependent with a sensitivity of 90% compared to that of CT which approaches 100%^4,5 If CT is available, it is preferable as the diagnostic modality for splenic abscess. ⁶

In our case, splenomegaly was attributed to P. vivax infection, but as the fever persisted despite antimalarial therapy, and left hypochondrial pain and discomfort worsened, the possibility of secondary infection was considered and sought for. In our case, this proved to be due to E. coli, the source of which was the urinary tract. In malaria, haematomas and micro-infarcts occur, which owing to depressed levels of cellular and humoral immunity, may become secondarily infected, particularly with salmonella. ⁷

Optimal management is still under debate, but a consensus is for a more conservative approach. This consists of initial antibiotic treatment and catheter drainage (CD). Simple blind antibiotic therapy without aspiration and drainage is considered inadequate. ⁸

Splenectomy is reserved for stable patients with multilocular abscesses, ill-defined cavities, septations and necrotic debris that are not amenable to CD. Haemorrhage is the most common complication of CD followed by pneumothorax, pleural effusion and colonic injury. ⁹ CD may be used in addition as a bridge to surgery in critically-ill patients. ¹⁰ However, the total success rate of CD is only approximately 50%. ¹¹

Nonetheless, splenectomy may be a difficult and hazardous procedure. As the spleen is fragile, it may readily bleed and cause purulent spillage into the peritoneal cavity. Furthermore, avoidance of splenectomy will avoid the potentially life-threatening infections due to complicated malaria Streptococcus pneumoniae, Haemophilus influenza and Neisseria meningitidis, which may occur post splenctomy.

A high index of infestation with Echinococcus granulosus must be entertained in endemic areas, especially if the abscess wall is calcified or the abscess contains a daughter cyst. ¹²

Where malaria fever does not respond to therapy, and particularly if there is associated left hypochondrial discomfort, an US scan will rapidly reveal an abscess collection. Discovery of this condition radically alters the management, the failure of which change may prove fatal for the patient.