Gastric wall abscess is a rare disease and difficult to diagnose. Due to the characteristics of the abscess, it is difficult to culture and the therapeutic effect of empirical antibiotics can be restricted. Until now, most gastric abscess required surgical intervention if there was no response to empirical antibiotics. However, endoscopic approach is emerging as an alternative method. Here we report a unique case of gastric wall abscess treated by endoscopic drainage and specified antibiotics by culture results. The patient provided written informed consent for the publication.

A 75-year-old man visited a primary medical clinic, presenting with epigastric pain, anorexia, and vomiting. He had a history of hepaticojejunostomy due to calculous cholecystitis. He was referred to our hospital and admitted for further evaluation of the mass found on the abdominal ultrasound. In the initial laboratory results, the white blood cell count was 10,550/mL and C-reactive protein level was elevated to 4.25 mg/dL (normal range, <0.05 mg/dL). Computed tomography (CT) of the abdomen identified about 4 cm sized low-density mass-like lesion with peripheral enhancement which invaded the gastric antral submucosa, which was compatible with abscess (Fig. 1A). A 6.4-cm-sized large mass with multiple small nodular lesions in peripheral portion compatible with abscess was detected in the left lateral segment of the liver. Later, the mass in the liver was diagnosed as intrahepatic cholangiocarcinoma by ultrasound-guided liver biopsy and positron emission tomography/CT. Treatment for gastric abscess with empirical broad-spectrum antibiotics (intravenous [IV] ceftriaxone 2 g every 24 hours) was initiated. Despite treatment, during the first 4 hospital days, his pain did not improve and fever up to 38.8°C developed. White blood cell increased to 16,480/mL and the C-reactive protein level increased to 6.66 mg/mL, but there was no growth in the blood culture. We changed antibiotics (meropenem 1 g IV every 12 hours) and performed an esophagogastroduodenoscopy with endoscopic ultrasonography (EUS). Esophagogastroduodenoscopy showed a huge subepithelial tumor (Fig. 1B) and EUS showed about 4.3×2.5 cm sized homogenous mass with mixed echo from the third layer at the anterior wall of the antrum, which filled with liquified material, and air fluid level was noted (Fig. 1C). We performed endoscopic incision and drainage immediately. After the injection of saline (Fig. 2A), about 1.5-cm-sized incision up to the submucosal layer was done by H-knife (Clear-Cut Knife H type, Finemedix Co., Ltd., Daegu, Korea) (Fig. 2B). Clear fluids gushed out from the opening (Fig. 2C). An endoscopic retrograde cholangiopancreatography catheter was introduced to the opening to the abscess pocket, and aspiration was done for the culture studies (Fig. 2D). About 20 mL of saline irrigation into the lesion was done. After the procedure, the lesion was markedly collapsed (Fig. 2E). Over the following 3 days, dramatic improvement of epigastric pain was achieved. The culture from the drained fluid detected Elizabethkingia anopheles (resistant to cefepime, ceftazidime, and meropenem; sensitive to ciprofloxacin and trimethoprim/sulbactam) and Candida albicans. We added ciprofloxacin (400 mg IV every 12 hours) and fluconazole (400 mg IV every 24 hours) during the hospital stay. Previous leukocytosis became normal at 4,810/mL and the C-reactive protein level decreased to 0.59 mg/dL. Finally, the patient restored appetite when he was discharged after 10 days after endoscopic incision and drainage. In the outpatient department, he received oral ciprofloxacin (500 mg twice a day) and proton pump inhibitor (esomeprazole 20 mg once a day) and planned surgery for the cholangiocarcinoma.

Figure 1. The radiologic and endoscopic features of case. (A) The gastric wall abscess with submucosal invasion of the antrum was seen (arrow). (B) Huge subepithelial tumor was seen at the anterior wall of the antrum. (C) Mass arising from the third layer was filled with liquified material.

Figure 2. The endoscopic procedures of the intramural gastric wall abscess. (A) The site of epinephrine and saline mixture injection. (B) The endoscopic incision was done by an H-knife, (C) clear fluids gushed out immediately. (D) Aspiration and irrigation was done by an endoscopic retrograde cholangiopancreatography catheter, and (E) the lesion was markedly collapsed.

An intramural gastric abscess is a localized form of phlegmonous gastritis.¹ The most common manifestation of phlegmonous gastritis is the diffuse involvement of the gastric submucosa extending into all layers of the gastric wall. A localized form is relatively rare, accounting for 5% to 15% of all phlegmonous gastritis.² A purulent inflammatory process results in the forming of a pocket of pus, usually in the antrum and pylorus, but it can develop in any location of the stomach.³ The submucosa of the involved lesion may be thickened, and the flattened mucosa almost looks intact, so we need to rule out subepithelial tumors such as gastrointestinal stromal tumors.⁴

As the pathogenesis of phlegmonous gastritis is unknown, the cause of the intramural gastric abscess is not certain. The possible causes are the direct bacterial invasion through the damaged gastric mucosa. Another source can be an infection by lymphatic or hematogenous dissemination.² To the best of our knowledge, the most common pathogens are Streptococci, Staphylococci, and Escherichia coli.⁴ In this case, C. albicans and E. anopheles were cultured. C. albicans are rarely reported as the pathogen, but this is the first report of E. anopheles as the pathogen of the gastric wall abscess.

First described in 2005, Elizabethkingia (nosocomial infection Gram-negative Chryseobacterium) infections are rare. It is an emerging bacterial pathogen for nosocomial condition since 2016.⁵ E. anopheles was first isolated from the midgut of the Anopheles gambiae mosquito in 2011⁶ and is the most frequently isolated Elizabethkingia species in recent clinical studies. It has natural resistance to carbapenems and a variety of potential infection sources, including healthcare products, water sources and the environment. To date, none of these have been found to be a source of the bacteria.⁷ Usually it was isolated from the patient who had major comorbidities and recent health care exposure. If identified in blood cultures the attributable mortality rate was 18.2%.⁸ As far as we know, there was no report for Elizabethkingia as the pathogen of gastric abscess. An appropriate choice of antibiotics by the isolation is important to reduce the duration of antibiotic treatment and mortality.

The intramucosal gastric abscess or phlegmonous gastritis is known to be related with heavy alcoholics, immunocompromised state such as human immunodeficiency virus infection, nutrition deficiency, diabetes mellitus, chronic kidney disease, leukemia, multiple myeloma, rheumatoid arthritis, and chronic steroid use. Also, the secondary type of phlegmonous gastritis is associated with the infection of other organs, such as biliary infection or hepatic abscess.^9-11 In our case, he had anorexia because of persistent vomiting and epigastric pain. Nutrition deficiency was another risk factor for poor general condition.

The protruding mass with normal-looking mucosal appearance of gastric abscess is similar to that of subepithelial tumors. CT and EUS are helpful in the diagnosis of gastric abscess. Enhanced abdominal CT shows a low-density mass with peripheral ring enhancement. A typical EUS finding is the thickening of the gastric wall with a localized hypoechoic mass, which has heterogeneously mixed echogenicity.¹² EUS is superior to CT scan in measuring the contents of mass, the depth, and extent of invasion. We could notice liquified materials and air-fluid level. Even after CT and EUS, it can be confused with cancerous lesions. To avoid misdiagnosis, fine-needle aspirationis are useful and if there is any purulent fluid leakage from the lesion site, an immediate and definite diagnosis of gastric abscess can be made.¹³

Until recently, the recommended therapy for an intramural gastric abscess was gastrectomy in combination with antibiotics. Nowadays, in order to avoid unnecessary surgery, the alternative method of initial treatment by endoscopic approach is recommended, and it has been shown to be effective. In prior studies, for the noninvasive treatment of the gastric abscess, endoscopic or percutaneous drainage was introduced.⁴

According to a previous report from 1972 to 2003, there were only 17 reported cases of intramural gastric abscess.⁴ The 16 (89%) patients of a total of 18 presented with abdominal pain. The 11 cases (61%) were performed by surgery and four (22%) cases with endoscopic drainage, and two (11%) cases with percutaneous drainage, and one (6%) case with antibiotics. Several publications since 2003 were reviewed, and 15 reported cases were identified including our case (Table 1).^3,4,13-22

Table 1 . Clinical Presentation and Treatment of Intramural Gastric Abscess.

Author (year)	Age (yr)	Sex	Symptom at presentation	Diagnostic method	Treatment	Survival
Chen et al. (2018)13	47	Female	Abdominal pain	CT/EUS	Surgery+antibiotics	Yes
Chen et al. (2018)13	31	Male	Abdominal pain	CE/EUS	Surgery+antibiotics	No
Jun et al. (2010)14	60	Female	Abdominal pain	CT/EUS	Endoscopic drainage+antibiotics	Yes
Odish et al. (2019)15	75	Female	Abdominal pain	CT/EUS	Antibiotics	Yes
Alonso et al. (2013)16	55	Female	Abdominal pain	CT	Endoscopic drainage+antibiotics	Yes
Ota et al. (2020)17	74	Male	Abdominal pain	CT/EUS	Endoscopic drainage+antibiotics	Yes
Park et al. (2021)18	74	Male	Nausea	CT	Surgery	Yes
Dohi et al. (2014)19	63	Female	Abdominal pain	CT	Endoscopic drainage+catheter insertion+antibiotics	Yes
Cole et al (2015)20	46	Female	Nausea	CT	Endoscopic drainage+antibiotics	Yes
Ergün et al. (2017)21	11	Male	Abdominal pain	CT	Antibiotics	Yes
Kimura et al. (2019)12	68	Female	Abdominal pain	CT	Endoscopic drainage+antibiotics	Yes
Marcos et al. (2010)22	48	Male	Abdominal pain	CT/EUS	Endoscopic drainage+catheter insertion+antibiotics	Yes
Kiil et al. (2001)3	63	Male	Esophagitis bleeding	EGD	Endoscopic drainage	Yes
Choong et al. (2003)4	75	Male	Abdominal pain	CT/EUS	Endoscopic drainage+antibiotics	Yes
Current study (2022)	75	Male	Abdominal pain	CT/EUS	Endoscopic drainage+antibiotics	Yes

CT, computed tomography; EUS, endoscopic ultrasonography; EGD, esophagogastroduodenoscopy..

The technical advances of endoscopic drainage procedure have emerged as an alternative to surgical approach these days. In our case, the abscess was treated with endoscopic aspiration and irrigation after endoscopic incision. First, the top of the mass was incised about 1.5 cm up to the submucosal layer by H-knife after saline injection. Then clear fluids flowed out from the opening. We used an endoscopic retrograde cholangiopancreatography catheter for the lavage of the submucosal abscess similar to a prior study.¹² An endoscopic retrograde cholangiopancreatography catheter was introduced to the incisional opening, and aspiration of the fluid for the culture study was done. Finally, 20 mL of normal saline was used to irrigate the abscess pocket. After the procedure, markedly collapsed mass was observed and the symptoms of the patient improved immediately. In other reports, which did not perform an incision, a pigtail catheter was left in place for 1 month to allow for additional drainage of pus.¹² This sequence of a sufficient incision, aspiration and irrigation without remaining pigtail catheter is a minimally invasive and inexpensive way to achieve the early treatment and safety, even a follow-up endoscopy is not mandatory.

To summarize, we report a rare case of gastric wall abscess with a rare pathogen, treated with minimally invasive endoscopic incision and drainage. Appropriately chosen antibiotics confirmed from the drained sample were also helpful. Because the endoscopic approach to gastric abscess is uncommon, we expect more reports, and sharing the experience of each treatment would be important.

No potential conflict of interest relevant to this article was reported.

Study concept and design: K.R.K. Data acquisition: K.R.K., K.N.S., A.R.C., M.J.L., Y.H.P., E.M.S., C.H.T., S.A.J. Drafting of the manuscript: K.R.K., K.N.S. Critical revision of the manuscript for important intellectual content: K.R.K., K.N.S. Administrative, technical, or material support; study supervision: K.N.S., A.R.C., M.J.L., Y.H.P., E.M.S., C.H.T., S.A.J. Approval of final manuscript: all authors.