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American Journal of Critical Care 2009 Levine

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By Steven M. Levine, MD, Spiros G. Frangos, MD, Bruce Hanna, PhD, Kari Colen, MD, and Jamie P. Levine, MD

Medicinal leeches are used to control venous congestion. Aeromonas in the leech gut are essential for digestion of blood. This case report describes a patient who had Aeromonas bacteremia develop after leeching. He had an injury to his hand that required replantation of his thumb. Following the surgery, leech therapy was started with ampicillin-sulbactam prophylaxis. Sepsis developed. Blood cultures were positive for Aeromonas that were resistant to ampicillinsulbactam. The antibiotic was changed to ciprofloxacin on the basis of the sensitivity profile of the organisms. Cultures from the leech bathwater confirmed it as the source of the Aeromonas. Clinicians who use leech therapy must be aware that leeches can harbor Aeromonas species resistant to accepted prophylactic antibiotics and that sepsis may occur.

Medicinal leeches (Hiruda medi cinalis) are used therapeutically to help control venous congestion in certain clinical settings, including extremity replantation. Leeches remove stagnant blood by direct drainage and localized anticoagulation that enables continued drainage and ultimately bridges the affected tissues until capillary angiogenesis repairs the tissue at risk. Individual leeches consume 5 to 10 mL of blood and cause the site of attachment to ooze between 50 and 100 mL of blood during the 24- to 48-hour period after the leech is detached. Leeches are normally placed in a serial fashion to relieve venous congestion and their use is tapered off as new vascular channels form and the tissue can support its own outflow safely

Aeromonas species are the prominent bacterial flora in the leech gut and are essential for digestion of blood. Wound infections occurring when medicinal leeches are used have been well described, and appropriate antibiotic prophylaxis (eg, β-lactamase–resistant drugs, quinolones, or trimethoprim-sulfamethoxazole) should be started in conjunction with leech therapy. We report a case of a patient who was not immunocompromised but had Aeromonas bacteremia develop as a result of medicinal leeching.

Case Report
A 52-year-old right-hand-dominant male smoker had a severe injury of his left hand caused by a circular saw. The injury required an attempted replantation of his thumb and revascularization of his second, third, and fourth digits. Although the injury was high risk for a poor vascular outcome, given the multidigit nature of the injury, an attempt for replantation was made to salvage the hand’s function. The patient was made aware of the potential difficulties and complications of attempted reattachment and revascularization, and the patient agreed with plans for digital reconstruction. Vascularized reattachment was performed on all the digits.

The patient had been treated with ampicillinsulbactam prophylactically after the injury because of the dirty nature of the injury. In the early postoperative period, leech therapy was initiated when venous congestion was noted that could not be surgically repaired. Antibiotic coverage was not changed or broadened at that time. In the next few days, the patient began spiking daily fevers (maximum temperature, 105.1ºF [40.6ºC] on day7) and sepsis was apparent (maximum leukocytosis, 20.5 x 109/L on day 3). No evidence of local wound infection was seen.

A VITEK 2 automated culture system (Bio-Merieux, Durham, North Carolina) was used to process blood and wound samples, and both types of samples were positive for Aeromonas veronii biovar sobria that were resistant to ampicillin-sulbactam. The patient’s antibiotic regimen was changed to ciprofloxacin on the basis of the sensitivity profile of the organisms. His symptoms immediately improved and the septicemia resolved. He returned to the operating room on day 16 for debridement of nonviable tissue on the replanted thumb but otherwise had an uneventful course. Culture results from leech bathwater, using the same VITEK 2 system, confirmed the source of the ampicillin-sulbactam–resistant Aeromonas sobria to be the medicinal leech.

The first recorded use of the medicinal leech dates back to ancient Egypt. Images of the leech adorned the walls in a sepulcher of the 18th dynasty pharoahs (1567-1308 BC). Galen, the physician to Marcus Aurelius, is credited for popularizing leech therapy. He postulated that bloodletting would correct the humoral imbalance in a patient and restore good health. Leeches reached their pinnacle of popularity in France in the late 18th century. Under the influence of Francois-Joseph-Victor Broussais, a chief surgeon in Napoleon’s army, treatments were so frequent that leeches were nearly unobtainable throughout Europe and the United States. In 1809, a Russian professor, Diakonov, wrote that the “lack of blood coagulation and dissolution of red blood corpuscles in the leech’s intestinal duct testifies that some dissolving agents exist there.” In 1884, Haycraft termed the anticoagulating substance contained in leech saliva hirudine. In 1955, Markwardt was the first to isolate hirudine from the pharyngeal glands of leeches.

In 1983, Whitlock et al reported A hydrophylia in the mucous secretions and gut of the medicinal leech. Shortly after, Dickson et al reported the first case of an Aeromonas wound infection related to use of the medicinal leech. Aeromonas has since been well described as a normal flora symbiote in the gut of medicinal leeches, as the leech lacks the proteolytic enzymes necessary to digest the blood it ingests.

Today, medicinal leeches remain in use, largely by microsurgeons, to aid in salvaging venous engorged tissue, including microvascular free flaps, pedicled flaps, amputated digits, ears, and nasal tips. A wide body of evidence suggests that the early application of a leech improves survival of venouscongested tissue.

Leeching therapy comes with the risks associated with introducing live biologic material into a fresh surgical site, namely infection with Aeromonas. Other minor disadvantages are patients’ inability to cope with the biologic therapy from a psychological standpoint and reports of minor pain at the site.

Our case is concerning in that sepsis developed in an immunocompetent man due to Aeromonas bacteremia acquired as a result of therapeutic leeching despite prophylactic antibiotics. Historically, ampicillin-sulbactam has been an acceptable regimen for Aeromonas infection prophylaxis, although quinolones currently show the broadest coverage against Aeromonas infections. Scattered reports of Aeromonas resistance to quinolones have been published, however, further highlighting the need to be cognizant of the real risk for septicemia surrounding the use of therapeutic leeching.

Medicinal leeches may harbor Aeromonas species resistant to accepted prophylactic antibiotics, and septicemia may complicate the course of even healthy patients undergoing leeching therapy.