Abstract
Infection with the bacterium Burkholderia pseudomallei can cause melioidosis, a potentially life-threatening disease. As a facultative intracellular pathogen, it poses challenges for treatment and demands long-term follow-up. Neck abscesses caused by Burkholderia are rare, but it is essential to consider their possibility, as prompt diagnosis and treatment are crucial for improving outcomes and preventing complications. We report three cases of neck abscesses that were treated.
Introduction
Melioidosis is a rare infection caused by a saprophytic Gram-negative bacillus, Burkholderia pseudomallei. Chronic renal disease, chronic liver disease, diabetes mellitus, alcoholism, cancer, connective tissue diseases, and immuno-suppressive medications are common risk factors for the development of melioidosis, whose mortality is nearly 50%. 1 The mortality rate may be reduced to 8% with appropriate intensive supportive care. 2 Clinicians may overlook the disease in their differential diagnoses, leading to potentially severe consequences. 3 The global pandemic of diabetes raises its risk by at least 12 times, especially in low- and middle-income tropical countries. 4
We report three cases of neck abscess due to B. pseudomallei, presented with a duration of six months, which were treated successfully. Written consent was obtained to include the clinical details of the cases and publish the photographs.
Case series
Case 1
A 40-year old female was referred with a swelling on the right neck for two weeks, which was treated with oral antibiotics but showed no improvement. On examination, an ovoid, tender swelling of 4 cm × 3 cm was present on the right side of the neck over the Level 2 lymph node region (Fig. 1). Ultrasonography confirmed a heterogeneously echogenic collection on the right side of the retromandibular region, measuring 3.8 cm × 2.8 cm.
Clinical photograph showing abscess below the angle of the mandible.
She had high blood sugar (17.8 mmol/L) and was treated with insulin for better control. After diagnostic aspiration, incision and drainage of 75 mL of pus was performed. Culture yielded a growth of B. pseudomallei, sensitive to Ceftazidime and Cotrimoxazole. She was treated with the former intravenously 1g bd for two weeks. Drainage of pus ceased after three days with daily dressing. Oral cotrimoxazole was continued for three months, after which complete resolution was achieved.
Case 2
A 24-year old female presented with throat pain and fever. On examination, she was febrile at 38.4 °C and had a congested pharynx with follicles on both tonsils and a tender, enlarged right upper cervical lymph node. She was treated with oral Amoxiclav 625 mg tds. After five days, the fever persisted with increasing fluctuant cervical lymphadenopathy, resulting in restriction of neck movement. Neck ultrasonography showed an organised abscess deep to the right sternocleidomastoid muscle, in the right upper jugular region.
Incision and drainage of 15 mL of pus was carried out, from which culture grew B. pseudomallei, sensitive to Ceftazidime and cotrimoxazole. Intravenous Ceftazidime 1g bd was thus administered for two weeks, followed by oral cotrimoxazole bd for three months, after which resolution had occurred.
Case 3
A 55-year old diabetic male presented with swelling in the anterior aspect of the neck for two weeks. On examination, a 2 cm × 3 cm fluctuant swelling was noted on the anterior aspect of the neck. Ultrasonography showed a thick-walled collection with internal echoes at the anterior aspect of the lower cervical region, adjacent to the sternomastoid muscle. Incision and drainage produced 50 mL of pus. Culture yielded a growth of B. pseudomallei, sensitive to Ceftazidime and Cotrimoxazole. Treatment with intravenous Ceftazidime 1g bd continued for two weeks, followed by three months of oral cotrimoxazole, at the end of which he was symptom-free.
Discussion
B. pseudomallei is a slender, motile, aerobic, oxidase-positive, catalase-positive, Gram-negative bacillus with bipolar staining. It will grow on most laboratory media, such as sheep blood, chocolate, and MacConkey agar, as smooth, creamy, white colonies with a characteristic musty odour. Specific Ashdown's medium will also show the growth. 5 Because of bacterial aerosolization, cases are most common during the rainy season. The bacteria are inherently present in the soil and enter the human body via inoculation, inhalation, or ingestion. 6
South Asia has 44% of the global disease burden. 7 Melioidosis manifests diversely in immunocompetent and immunocompromised patients: asymptomatic, localised tissue infection, necrotising pneumonia, soft organ abscesses, life-threatening respiratory distress, and septic shock. The average incubation period ranges from nine days to several years.
Although the exact mechanism is unknown, B. pseudomallei can survive and multiply inside phagocytes. This may be the reason for the difficulty in eradicating melioidosis, even though antimicrobial agents are effective against the organism in vitro. 8 As a result, long-term courses of oral antibiotic therapy are advised to ensure complete eradication. 9
Intravenous administration of Ceftazidime or Meropenem is preferred for initial intensive therapy, for at least 10–14 days, extended for more complex cases. Cotrimoxazole (trimethoprim–sulfamethoxazole) is the preferred long-term eradication agent worldwide. Amoxicillin–clavulanate serves as an alternative for children and pregnant women. 10
Recrudescent melioidosis can occur with a relapse of symptoms and culture positivity, especially if initial intensive therapy is inadequate, if abscesses are not drained completely, or if eradication therapy is incomplete. 11
B. pseudomallei may remain for a prolonged period up to 26 years in tissues. 12 The development of a melioidosis vaccine, driven by concerns over the biothreat potential of B. pseudomallei and its relevance for military applications, is on the horizon. 10
Footnotes
Declaration of conflicting interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.
