Chromobacterium haemolyticum infection from hot springs near Yellowstone National Park: a case report
Abstract
Chromobacterium haemolyticum is a gram-negative anaerobic sporulated rod and was only first identified in 2008. It is very rare in people with only a handful of cases having been diagnosed around the world.
After suffering a fall near Yellowstone National Park, a white male patient in his 50 s presented to a hospital in Eastern Idaho. With many unexplained symptoms, several changes in patient stability and recovery, over a course of 18 days in the hospital, the infecting organism could not be easily identified. Labs in the hospital, state, and eventually outside of the state were consulted for pathogen identification, which was only accomplished after the patient was discharged.
To our knowledge, this is only the seven reported human infection with Chromobacterium haemolyticum. This bacterium is difficult to identify and may be occur in rural areas without the proper testing facilities to quickly identify the pathogen, which is essential to timely treatment.
Background
Chromobacterium haemolyticum is a gram-negative anaerobic sporulated rod. It has been found in tropical and subtropical bodies of water [1,2]. It causes bacillary hemoglobinuria (i.e., red water disease) most often in cattle though occasionally in sheep, horses, pigs, and elk and is usually fatal [3]. C. haemolyticum produces several toxins including: phospholipase (beta toxin), tropomyosinase (eta toxin), and a lipase (theta toxin) [3].
Most human infections with chromobacterium are with violaceum [4]. It is important to differentiate between the two as C. haemolyticum displays more resistance to antimicrobial drugs than C. violaceum [5,6]. However, infection with C. haemolyticum was first described in 2008 [5]. There have been seven reported human infections with C. haemolyticum [5,6,7,8,9,10,11]. These infections have occurred over a wide geographical range, including several in Japan, one in Thailand, and two in the United States (Ohio and Texas). Of these cases, multiple conditions have been reported including necrotizing fasciitis with bacteremia, pneumonia, proctocolitis, pediatric bacteremia, and meningitis [6,7,8,9,10,11]. Here, we present a case of infection with C. haemolyticum discovered in a patient in Idaho, near Yellowstone National Park.
Case presentation
A white male patient in his fifties presented to a hospital in Eastern Idaho via helicopter after traumatic fall at Yellowstone National Park. During a hike, he slipped on wet rocks and fell six feet into a natural hot spring where he remained for eight hours while he awaited rescue. When the patient fell, he suffered a left knee laceration and left closed femur fracture, necessitating airlift. X-ray imaging in the emergency department confirmed a closed, displaced left femoral diaphyseal fracture later repaired with same-day open reduction and internal fixation (ORIF). The patient requested to be discharged home in the immediately postoperative period, however due to a drop in hemoglobin from 12.0 g/dL to 9.4 g/dL, it was recommended that the patient remain in the hospital. Two days postoperatively, the patient exhibited leukocytosis, differential diagnosis including postoperative elevation versus sepsis. There was a further decrease in his hemoglobin down to 8.0 g/dL on repeat check several hours later despite no hematoma evident on physical exam, and the patient subsequently developed a fever of 103 °F (39.4 °C) and tachycardia up to 130 beats per min. Stat orders were placed for blood cultures, complete blood count with differential, and lactate, with the left thigh noted to be firm in comparison to the surrounding tissue. Antibiotic treatment with Cefalexin was initiated at that time. By day five, the patient was noted to have polydipsia, drinking in excess of eight liters per day, and reported feeling “loopy.” Labs demonstrated hyponatremia, hypokalemia, and a hemoglobin of 7.3 g/dL, C-reactive protein of nearly 30 mg/dL, and persistence of tachycardia and fever despite a drop in his white blood cell count from 14.4 K/mm3to 8.5 K/mm3. Blood cultures demonstrated growth of gram negative rods in four of four bottles with further identification pending, however the patient’s clinical deterioration provided sufficient evidence for the infectious disease specialty service to broaden the antibiotics from Cefalexin to Cefepime and Metronidazole. During the sixth night, repeat hemoglobin of 6.9 g/dL and suspicion of active bleeding prompted transfusion of two units of blood. Due to limitations of the in-house lab, the isolated pathogen was unable to be identified, although it was determined that the organism was a non-lactose fermenting, non-Aeromonasgram negative rod resistant to Cefepime. The culture was sent to a separate lab for definitive identification. The patient was transitioned to 750 mg of Levofloxacin daily for 10 days. On day 8, the patient was afebrile with improvements in heart rate, blood pressure, and hemoglobin, however white blood cell count remained elevated at 13.6 K/mm3and left thigh remained firm with edematous. Pain and edema continued to increase and computed tomography scan without contrast of the lower extremity demonstrated subcutaneous edema throughout the soft tissues of the left thigh. On day 9, the patient continued to exhibit increased lower extremity edema and antibiotics were switched from Levofloxacin to Meropenem at the recommendation of the infectious disease service. Despite broadened antibiotic coverage and attempted diuresis with intravenous furosemide

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