Microwave ablation of liver metastasis complicated by Clostridium perfringens gas-forming pyogenic liver abscess (GPLA) in a patient with past gastrectomy

Abstract

Introduction:
Gas-forming pyogenic liver abscess (GPLA) caused by C. perfringens is rare but fatal. Patients with past gastrectomy may be prone to such infection post-ablation.

Presentation of case:
An 84-year-old male patient with past gastrectomy had MW ablation of his liver tumors complicated by GPLA. Computerised tomography scan showed gas-containing abscess in the liver and he was managed successfully with antibiotic and percutaneous drainage of the abscess.

Discussion:
C. perfringens GPLA secondary to MW ablation in a patient with previous gastrectomy has not been reported in the literature. Gastrectomy may predispose to such infection. Even in high-risk patients, empirical antibiotic before ablation is not a standard of practice. Therefore following the procedure, close observation of patients' conditions is necessary to allow early diagnosis and intervention that will prevent progression of infection.

Conclusion:
Potential complication of liver abscess following MW ablation can never be overlooked. The risk may be enhanced in patients with previous gastrectomy. Early diagnosis and management may minimise mortality and morbidity.

Full text

Accepted Manuscript
Title: Microwave ablation of liver metastasis complicated by
Clostridium perfringens gas-forming pyogenic liver abscess
(GPLA) in a patient with past gastrectomy
Author: Lee S. Kyang Thamer A.Bin Traiki Nayef A.
Alzahrani David L. Morris
PII: S2210-2612(16)30304-2
DOI: http://dx.doi.org/doi:10.1016/j.ijscr.2016.08.009
Reference: IJSCR 2065
To appear in:
Received date: 18-5-2016
Accepted date: 6-8-2016
Please cite this article as: Kyang Lee S, Traiki Thamer ABin, Alzahrani
Nayef A, Morris David L.Microwave ablation of liver metastasis complicated
by Clostridium perfringens gas-forming pyogenic liver abscess (GPLA) in a
patient with past gastrectomy.International Journal of Surgery Case Reports
http://dx.doi.org/10.1016/j.ijscr.2016.08.009
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Microwave ablation of liver metastasis complicated by Clostridium perfringens gas-
forming pyogenic liver abscess (GPLA) in a patient with past gastrectomy
Lee S. Kyang*, Thamer A. Bin Traiki±, Nayef A. Alzahrani¿, David L. Morrisł
*St George Clinical School, University of New South Wales, New South Wales,
Australia
± Department of Surgery, St George Hospital, University of New South Wales, Sydney,
New South Wales, Australia
¿ Department of Surgery, St George Hospital, University of New South Wales, Sydney,
New South Wales, Australia; Imam Muhammad ibn Saud Islamic University College of
Medicine Riyadh Saudi Arabia
ŁDepartment of Surgery, St George Hospital, University of New South Wales, Sydney,
New South Wales, Australia
Correspondence details
Home address: 23/286-292, Fairfield St., Fairfield NSW 2165
Mobile number: +614 50 332 606
Fax number: NA
Email address: frank.ls01@hotmail.com (please address to email)

Highlights
 GPLA is one rare complication of liver microwave ablation
 It can be diagnosed with CT scan which shows gas-containing infective focus
 Patients with gastrectomy may have an increased risk of such infection due to gut
flora change
 To date, data on effectiveness of empirical antibiotic is not convincing
 Close monitoring following ablation should be prioritised to allow timely
intervention and prevent escalation of infection

Abstract:
Introduction
Gas-forming pyogenic liver abscess (GPLA) caused by C. perfringens is rare but fatal.
Patients with past gastrectomy may be prone to such infection post-ablation.
Presentation of case
An 84-year-old male patient with past gastrectomy had MW ablation of his liver tumors
complicated by GPLA. Computerised tomography scan showed gas-containing abscess
in the liver and he was managed successfully with antibiotic and percutaneous drainage
of the abscess.
Discussion
C. perfringens GPLA secondary to MW ablation in a patient with previous gastrectomy
has not been reported in the literature. Gastrectomy may predispose to such infection.
Even in high-risk patients, empirical antibiotic before ablation is not a standard of
practice. Therefore following the procedure, close observation of patients’ conditions is
necessary to allow early diagnosis and intervention that will prevent progression of
infection.
Conclusion

Potential complication of liver abscess following MW ablation can never be overlooked.
The risk may be enhanced in patients with previous gastrectomy. Early diagnosis and
management may minimise mortality and morbidity.
Keywords:
Clostridium perfringens infection; gas-containing abscess; microwave ablation; liver
tumor; gastrectomy; prophylactic antibiotic

Introduction:
Image-guided thermal ablation therapy, such as radiofrequency (RF) and microwave
(MW) ablations, serves as an alternative to surgery for liver metastasis, especially in
patients deemed not suitable for surgery. They aim to destroy tumor cells using heat
while doing minimal damage to the surrounding structures or organs. They are
relatively safe with low complication rates1. Of all major complications, pyogenic liver
abscess happens in less than 2% of all hepatic RF ablations. Liver abscess complicated
by gas-forming bacterial infections is even less, accounting for 7-24% of all pyogenic
liver abscesses2. To our knowledge, there has been no case report on C. perfringens
GPLA post-MW ablation in patient with gastrectomy. Here, we report this potentially
fatal complication associated with MW ablation in a patient with previous gastrectomy
and review the literature pertinent to C. perfringens GPLA and the use of prophylactic
antibiotic prior to ablation.
Presentation of case:
An 84 years old male underwent total gastrectomy for his gastric adenocarcinoma in
2014. Past medical history is unremarkable. Subsequent follow-up a year later revealed
new onset of 4 liver lesions (segment VIII: 3 cm; segment VII: 2.8 cm; segment VI/VII:
2.3 cm; segment VI: 4.2 cm) consistent with metastatic adenocarcinoma (figure 1). An
attempt to treat the tumor with oral chemotherapy was unsuccessful and the patient
declined intravenous chemotherapy due to potential side effects. He accepted the option
of ultrasound-guided percutaneous MW ablation, which was performed under general
anesthesia. No preoperative prophylactic antibiotic was administered. An initial non-
contrast CT of the liver was captured to visualise the locations of lesions. Under sterile

conditions, a total of seven MW ablations were performed at the tumor sites using
Apparatus for Microwave Ablation “AMICA” (Mermaid Medical, Stenløse, Denmark),
equipped with a 17-Gauge needle. At segment VIII, two ablations were made at power
settings of 60 Watts for 5 minutes. Similarly, two ablations of 60 Watts were made for
tumors at segment VII and segment VI for 5 minutes and 10 minutes, respectively.
Finally, one ablation was performed at 60 Watts for 10 minutes at the lesion in segment
VI/VII. Ablation margins of 1cm were achieved for all target lesions. No immediate
complications were reported and the patient was sent to the ward with ongoing PRN
analgesia.
A day following the procedure, patient complained of mild abdominal pain most
prominent on right upper quadrant. Vital signs were normal (temperature 37.4; blood
pressure 110/60; respiratory rate 17; heart rate 60); full blood count and liver function
test were unremarkable. However, on day 2 the patient reported shivering and looked
uncomfortable. On examination, he was febrile (39.6), tachycardic (125 bpm),
tachypneic (25 bpm) and desaturating at 93%, requiring 2 litres of oxygen with nasal
prong. Blood pressure was 155/75. His abdomen was soft, non-tender and not distended.
Nil percussion or rebound tenderness was elicited. The rest of physical examination was
normal. Initial treatment focused on intravenous fluid hydration and administration of
broad spectrum antibiotics (ceftriaxone and metronidazole). Urinalysis was insignificant
while chest x-ray demonstrated no signs of free air. Blood tests showed normal white
cell count (4.01 x 109/L), deranged liver enzymes (AST 825; ALT 894) and blood
culture yielded positive growth of gram-negative bacilli (Escherichia coli) sensitive to
ceftriaxone.

On day 3, the patient remained febrile clinically and had signs of peritonitis on his right
abdomen. This led to abdominal computed tomography (CT) with oral contrast, which
revealed a gas-containing pyogenic liver abscess (GPLA) within segment VIII where
the ablation was performed (figure 2). The patient was managed with percutaneous
drainage of the abscess, which was positive for Clostridium perfringens and
Escherichia coli, and the intravenous antibiotics were switched to a 2-week course of
tazocin. Progressively, clinical and infection parameters (temperature, white cell count
and C-reactive protein) improved. Later, a progress scan revealed reduction of the
diameter of the abscess in segment VIII. Patient was then discharged home on
21/12/2015 with liver drains in situ, which will be removed when output is minimal. He
was also given a 10-day course of oral amoxicillin and clavulanic acid (Augmentin DF).
No ethic approval by local Institutional Review Board (IRB) is needed for this case
report.

Discussion:
Incidence of pyogenic liver abscess following ablation may be well-documented.
However, C. perfringens GPLA secondary to MW ablation in a patient with previous
gastrectomy has not been reported in the literature. C. perfringens is a gram-positive,
anaerobic rod often populating in the soil. It can be isolated in gastrointestinal and
urogenital tracts of humans. C. perfringens can cause infections such as liver abscess,
lung abscess and soft tissue infection. If left untreated, it could escalate rapidly into
septicaemia, resulting in life-threatening situation and, ultimately, death in 70% -100%
of patients3. Risk factors for such deterioration include diabetes mellitus, liver cirrhosis
or immunocompromised state.
The exact mechanism of abscess formation post-ablation is not clearly established. We
considered whether bowel injury was responsible for our case but even retrospective
reviewed scans do not show any proximity of colon to the treatment site or probe tracks.
Therefore, it could most likely arise from the disruption of liver architecture that could
occur during MW ablation, thereby connecting bile duct and ablation zone which would
provide a pool for growth of enteric bacteria4. For our patient, previous history of
gastrectomy cannot be overlooked. Stomach provides an acidic environment which kills
off microorganisms and removal of this barrier, in return, may increase growth of
enteric bacteria in the upper gastrointestinal mucosa5. We hypothesise that the previous
gastrectomy in this patient might have resulted in retrograde colonisation of the biliary
tree with gut organisms.

According to practice guideline, no consensus has been made on the effectiveness of
routine prophylaxis due to lack of randomized controlled trials; therefore, the decision
to use prophylaxis varies with operators10. At our institution, we do not administer
empirical antibiotic before hepatic tumor ablation because we argue that it may not be
necessary given both the sterile nature of the procedure and the lack of solid evidence
supporting the use. However, recent study shows it may be feasible in high risk patients
such as elderly, those with diabetes, bilioenteric anastomosis (BEA) or other biliary
issues and tumor positioned near central bile duct11. Retrospectively, taking into account
of our patient’s advanced age and past history of gastrectomy, we wonder whether such
complication can be avoided should prophylaxis was given prior to the procedure.
Nevertheless, Shibata and colleagues concluded that, albeit trend appears to favour
some sort of prophylaxis, lack of antibiotic do not predispose to the development of
infection12. We believe that until more evidence proving the effectiveness of empirical
antibiotic surfaces, clinicians should instead be mindful of such complication and be
focused on careful post-treatment monitoring to allow early diagnosis and intervention.
Rapid diagnosis of patients with C. perfringens GPLA is paramount in improving
patients’ clinical outcomes. The initial presentation can be variable with abdominal pain
and fever most frequently reported6. In the settings of MW ablation, the nonspecific
symptoms could prove challenging to the diagnosis as it could mimic post-ablation
syndrome. This was clearly reflected in our case whereby his complaint of mild right
upper quadrant pain on day 1 post-ablation was not immediately addressed with
appropriate workup. The most reliable clinical investigation that could aid in diagnosis
is appearance of gas-forming liver abscess on imaging7. The presence of gram-positive

rod on blood culture may be helpful but should not always be relied upon in the
diagnosis of C. perfringens GPLA because it does not always reflect the microbiology
of the GPLA, as highlighted in our case8. Immediate treatment of patient can be life-
saving if there is sufficient clinical ground to suspect C. perfringens GPLA. Such
circumstance warrants aggressive managements which include percutaneous or surgical
evacuation of infectious focus, administration of relevant antibiotics and supportive
measures to sustain organ functions9. In hindsight, the early administration of empirical
antibiotics (ceftriaxone and metronidazole) and aggressive abscess drainage might
explain the excellent prognosis in our patient.
Conclusion:
Overall, our case illustrates a rare complication of MW ablation in a patient with
previous gastrectomy. Patients with previous gastrectomy may be prone to such
infection as a result of gut flora alteration. While administration of prophylactic
antibiotic may be necessary in patients with possible risk factors for liver abscess, the
efficacy of prophylactic antibiotic before hepatic ablation in general remains sceptical.
Instead, clinicians should be mindful of such complication and should closely monitor
these patients following procedure. It is imperative to follow diagnosis with aggressive
management by the means of infection drainage, intravenous antibiotics and supportive
measures.

Acknowledgements:
The authors declare that they have no conflict of interest. This research did not receive
any specific grant from funding agencies in the public, commercial, or not-for-profit
sectors.
Ethical standards:
Ethical approval was not required and patient identifying knowledge was not presented
in this report.
Consent
Written informed consent was obtained from the patient for publication of this case
report and accompanying images. A copy of the written consent is available for review
by the Editor-in-Chief of this journal on request.

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Figure Captions
Figure 1: Pre-ablation MRI (DWI-sequence) showing the locations of the four liver
metastases.
A: A 3-cm (arrow) and 2-cm (line) liver metastases are seen in segment VIII and segment VII,
respectively
B: A 3-cm liver metastasis is seen in segment VI (arrow)
C: A 1-cm liver metastasis is seen in segment VI/VII (arrow)

Figure 2: A gas-forming pyogenic liver abscess is seen at the ablation zone in segment
VIII (arrow)