A 45-year-old diabetic female presents to an emergency room in Dhaka, Bangladesh with a 3-day history of chills, high grade fever, cough, exertional dyspnea and pleuritic chest pain.  She was recently displaced from her home in a small village east of Dhaka during the monsoon storm. During her escape from the floods, she had to swim across a flooded ravine.

Upon examination she looks acutely unwell and auscultation of her lungs reveals bilateral crepitations. Small patchy bilateral infiltrates are seen on chest X-ray imaging.  Blood and sputum cultures are sent, and the patient is started on broad spectrum antibiotics.

Based on the above history what is the most likely diagnosis:

1. Malaria
2. Typhoid Fever
3. Melioidosis
4. Mycobacterial infection

Answer: Melioidosis

This was a case of melioidosis.  Melioidosis is an infection caused by the facultative intracellular gram-negative bacterium, Burkholderia pseudomallei. It is an environmental saprophyte in soil and fresh surface water in endemic regions such as Southeast Asia, Northern Australia, and China. It can be acquired through inhalation, inoculation and occasionally ingestion. Cases of inhalation are increased following times of heavy rainfall and flooding.

Host risk factors for melioidosis include diabetes, alcohol abuse, chronic kidney disease and chronic lung disease. It can present with a variety of clinical manifestations ranging from acute septicemia to chronic indolent disease. Latent infection with subsequent reactivation has been reported among veterans from the Korean and Vietnam wars (hence the name “Vietnamese Time Bomb” that it is sometimes given). Pneumonia is the most common clinical presentation, other clinical syndromes include genitourinary infection, skin and soft tissue abscesses, osteomyelitis and neurological manifestations.

Given the patient’s specific pulmonary symptoms and X-ray findings, malaria and typhoid, although endemic to the area, are less likely as these infections do not classically cause pulmonary disease. The characteristic presentation for typhoid fever would be fever followed by the formation of erythematous skin lesions known as Rose spot’s, usually seen on the abdomen, along with a predominance of GI symptoms  (diarrhea being the most common). Malaria is associated with non-specific symptoms in the setting of a high grade tertian or quartan (every three to four days) fever, with chills and rigors. In addition, the acuity of her symptoms and chest X-ray findings make Mycobacterial infection less likely.

The diagnosis of melioidosis is through routine culture and stains, however it is commonly misidentified as a bacillus on Gram stain. The characteristic bipolar staining and “safety pin” appearance can be seen on Gram stain of blood and sputum specimens. Treatment consists of two phases: an intensive phase, followed by an eradication phase. The intensive phase involves intravenous antimicrobial therapy for a minimum of 10 – 14 days with ceftazidime, meropenem, or imipenem. The eradication phase consists of oral therapy with trimethoprim-sulfamethoxazole (TMP/SMX) for 3–6 months.

The cases this week were submitted by Ahmed Babiker, 1st Year ID Fellow at Pitt.

An excellent 2012 Review from the NEJM can be found here.