Traumatic Wound Myiasis: An Unusual Finding in Maxillofacial Trauma

© 2007 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 65:2086-2089, 2007

Rajesh Gutta, BDS,* Luis Vega, DDS,†
and Patrick J. Louis, DDS, MD‡


*Formerly, Resident, Oral and Maxillofacial Surgery; Currently, Assistant Professor, Department of Oral and Maxillofacial Surgery, UTHSCSA, San Antonio, TX.
†Formerly, Resident, Oral and Maxillofacial Surgery; Currently, Assistant Professor, Department of Surgery, Division of Oral and
Maxillofacial Surgery, University of Florida, Jacksonville, FL.
‡Director, Oral and Maxillofacial Surgery Residency Program. Address correspondence and reprint requests to Dr Gutta: Mail Code 7908, Department of Oral and Maxillofacial Surgery, UTHSCSA, 7703 Floyd Curl Dr, San Antonio, TX 78229; e-mail: rajeshg76@yahoo.com


Myiasis is the term derived from the Greek word for fly, or myia. Myiasis is the infestation of living vertebrates by the larvae (maggots) of dipterous (2-winged) flies.1 Myiasis of traumatic or surgical wounds is seen occasionally in many big city hospital emergency departments during summer months and is caused by several fly species.2 It is estimated that about 7,000 cases of myiasis occur annually in the United States.3 About 671 publications on human myiasis were indexed between 1960 and 1995. Of these, 72 articles described 137 cases of United States-acquired myiasis.2 Many cases of myiasis go unreported as a result of “cultural, social, and medico-political reasons.”4 However, wound myasis is a rather uncommon finding in the maxillofacial trauma setting in developed countries; only 5 cases were reported of which only 1 case was reported from a developed country. We present a case of traumatic wound myiasis in the maxillofacial region.


Report of a Case


A 67-year-old white male presented to the emergency department with a history of being wounded several times in the head and left arm the night before presentation to the emergency department. The patient was found lying down in an apartment and was escorted to the emergency department for evaluation. The patient was awake and alert on arrival to the emergency department. His past medical history was significant for laryngeal cancer and he underwent a laryngectomy with tracheostomy in 2000. The patient’s medication on admission was albuterol inhaler as needed and he denied any drug allergies. His social history was significant for alcoholism.

On arrival to the emergency room, the trauma team was activated. The primary survey was intact. Vital signs and lab values were all within normal limits. Secondary survey showed extensive scalp and forehead lacerations measuring up to 63 cm with exposure of the cranium. The patient also sustained multiple lacerations to the left hand including a 6 cm laceration to the left wrist with exposed tendons. No significant findings were noted other than the lacerations as
described above. An extensive radiographic evaluation was carried out and it was negative for other injuries.

After initial trauma resuscitation, the Oral and Maxillofacial Surgery and the Orthopedic-Hand Services were consulted for wound management. A decision was made to wash the wounds thoroughly and close the lacerations in the emergency department under sterile conditions. Because the patient presented more than 30 hours after the initial event, his hair was shaved for effective wound care. The patient’s head was isolated, prepped, and draped in a sterile fashion. Copious irrigation of the wound with Betadine (Purdue Frederick Co, Norwalk, CT) and saline was carried out. All the wound margins were closed with a layer of deep sutures and the skin was stapled with stainless steel surgical staples. Antibiotic ointment was applied to the wound and a head dressing was placed. Subsequently, the patient was given a prescription for cephalexin 500 mg, to be taken every 6 hours for 7 days. He and his family were instructed in wound care and he was discharged home with a follow-up appointment in 1 week.

The patient reported subsequently to the emergency department 5 days after the initial visit. His complaint was, “something is creeping in my head.” The patient stated that since discharge, he had been taking the antibiotics but he did not remove the head dressing until the morning of his visit. At that time he noticed a foul smell (Fig 1). On presentation, the patient was febrile with a temperature of 101.9°C. However, other vital signs and lab values were within normal limits. Physical examination showed a foulsmelling scalp wound with extensively repaired lacerations and a small area (2 _ 2 cm) of wound dehiscence with exposed calvarium and maggots present. Examination of the left wrist laceration did not show any signs of infection or infestation. Subsequently, an oral and maxillofacial surgery consult was obtained for wound management.

The patient was immediately transported to the operating room for surgical debridement. In the operating room, the patient underwent general anesthesia induction via the tracheal stoma and the patient was prepped and draped in a sterile fashion. All scalp wounds were reopened, a large number of maggots were removed manually and sent for identification analysis. Wound cultures were obtained and the necrotic wound margins were excised. Surprisingly, there was minimal necrotic tissue present. The wounds were pulse irrigated with 8 liters of Betadine and saline mixture and an additional 4 liters of normal saline. A halfinch Penrose drain (CR Bard Inc, Covington, GA) was placed and the lacerations were then closed with 2.0 Monocryl deep sutures (Ethicon, Somerville, NJ) and the skin was closed with stainless steel staples (Fig 2). After the procedure, the patient was transported to the recovery room in satisfactory condition. Review of culture data showed colonization of the wound by Provindencia rettgeri, Klebsiella oxytoca, Streptococcous agalactiae. All the micro-organisms were sensitive to ciprofloxacin. The patient was discharged 24 hours after the procedure with thorough written and verbal wound care instructions. He was sent home with a prescription for ciprofloxacin 500 mg twice a day for 5 days. He was given a follow-up appointment in 1 week. Subsequent follow-up visits at 1 week, 3 weeks, and 8 weeks showed good healing without any recurrence of maggot infestation or soft tissue defect (Fig 3).

The larvae specimens that were sent for identification were confirmed as Phaenicia sericata (green bottle fly/blowfly).

Discussion

Ambrose Pare first noted the effects of maggots on battle wounds in 1557. He stated, “the wounds of the hurt people were greatly stinking, and full of worms with gangrene and putrefaction.”6 However, the wound healing and antimicrobial properties of maggots have been well known since the beginning of the 20th century.5 In 1917, Baer noted the beneficial effect of maggots on open battle wounds. He commented that, “although the wounds were swarming with maggots, the men were constitutionally well, with no evidence of septicemia or blood poisoning.”7

Members of the family Calliphoridae, a fly family rich in genera and species, cause myiasis. Myiasis is often classified according to the anatomic position in, or on, the animal that the larvae infest. Broadly speaking, they may be described as dermal, subdermal, or cutaneous, nasopharyngeal, ocular, intestinal/enteric, or urogenital. When open wounds are involved, the myiasis is known as traumatic and when boil-like, the lesion is termed furuncular. Most Calliphorid species search for carrion (dead or rotting flesh) as the preferred substrate in which to lay their eggs. Uncommon alternative choices for egg laying include feces or, occasionally, the fetid discharge from wounds or body orifices. In humans, the host averaged 60 years of age, with a male:female ratio of 5.5:1. Homeless-ness, alcoholism, and peripheral vascular disease were cited as frequent cofactors.2 In our case, homelessness may have increased his exposure to flies or to refuse frequented by flies.

Green blowfly, Phaenicia sericata is a common fly of temperate North America.8 Many of these flies tend not to invade living tissue, a feature exploited by practitioners of maggot debridement therapy.9 Obligatory myiasis- causing larvae infest living hosts and tend to be more invasive than the facultative parasites, which favors dead hosts or necrotic tissue of the living hosts.10

Maggots separate the necrotic tissue from the living tissue, making surgical debridement of the wound easier. The proposed mechanisms of maggot-induced wound healing included: 1) continuous flushing or irrigation of the wound by the copious exudates formed by the host in response to the maggots11; 2) killing, ingestion, and digestion of bacteria by the maggots; 3) secretion of allantoin (component of fetal allantoic fluid)12; 4) the rapid formation of granulation tissue stimulated by the continuous larval movement in the wound13; 5) liquefaction of necrotic tissue by the maggots14; and 6) maggot extracts stimulated significant increases in total human fibroblasts.15

Blowfly eggs typically hatch in a range from 8 to over 80 hours. Multiple reasons have been quoted for the cause of wound myiasis including: 1) helpless and debilitated patient; 2) blood or odors of decomposition; 3) nursing neglect; and 4) summer season.16

Antimicrobial qualities have also been assigned to the secretion of maggots. This effect seems to be predominantly on gram-positive bacteria.17 Some antibiotics have been shown to have effects on fly larvae.
A study on the effects of seven antibiotics on the growth and development of Phaenicia sericata larvae showed that cefazolin led to a significant decrease in larval survival by 70% with a concentration of 100 times the average bacteriostatic levels. With 1,000 times the normal pharmacologic concentrations, gentamycin led to a decrease in larval survival by 97.3%. The other antibiotics like ampicillin, ceftizoxime, clindamycin, mezlocillin, or vancomycin had no effect on the survival of the larvae. Based on the above results it is clearly evident that routine antibiotics have little value in the treatment of wound myiasis compared with conventional surgical debridement therapy.18

Before starting antibiotic therapy on the patient, blood cultures should be obtained to rule out sepsis. Blood ammonia levels should also be drawn because maggot-induced ammonia toxicity has been reported in humans with heavy maggot infestation.19

Unlike almost any other clinical specimen, maggots are often discarded (in haste and with disgust), rather than submitted to the clinical laboratory for analysis The maggots caught should be submitted to the clinical laboratory in saline, alcohol, or formaldehyde for analysis and documentation.

No effective chemotherapeutic agents are available for the treatment of any form of myiasis.20,21 The usual and most prudent medical response to such infestations is removal of the larvae to prevent tissue damage and bacterial infection, even when the maggots are known to belong to a therapeutically useful species. Irrigation with either chloroform or ether is advocated. This should immobilize the larvae. Surgery is often required. For identification, the larvae should be hatched to adult flies, or first killed by immersion in nearly boiling water, then cooled and preserved in 80% ethanol.22,23

Natural infestations with these maggots can have beneficial effects and these will be lost when the larvae are removed. Nevertheless, natural infestations are uncontrolled and can, therefore, complicate ongoing medical treatment. Prevention of myiasis involves controlling the source of the larvae, the ovipositing female fly.
It is hoped that this case report will be useful in the evaluation and treatment of patients with myiasis. Histories and physical examinations always must be comprehensive. The condition of the patient’s hygiene and clothing must be noted. All wounds should be thoroughly cleansed, and tetanus immunoprophy-laxis hould be updated as necessary. Follow-up within a week should be standard practice; antibiotics need to be prescribed only when indicated by signs of bacterial infection.

References
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