Continuing with our summer bite series

A 5-year-old boy was admitted to the hospital for evaluation and treatment of an infected dog bite to the face and lip.

He sustained what was described as an unprovoked bite by a neighbor’s German shepard to the right side of his face five days earlier and was immediately taken to a local emergency room.

There, the face wound was cleaned, irrigated and glued closed with Dermabond (Ethicon). The small, full-thickness lip injury was cleaned and left open. He was sent home with amoxicillin-clavulanate to take at a dose of 200 mg twice per day for infection prophylaxis. The next day, he began running fever and was seen by his primary provider, but since his wound did not appear to be infected, he was continued on the amoxicillin-clavulanate and told to return the next day. At that visit, the bite site was still glued closed, swollen with erythema, and he was sent for admission.

During this time, the dog was taken to their local veterinarian where his rabies immunizations were documented up to date and detained for evaluation per protocol.

The patient’s past medical history is positive only for having had an orchiopexy a year earlier and bilateral inguinal herniorrhaphies four years earlier.

His immunizations were documented to be up to date for his age.

His review of systems was unremarkable except for the chief complaint and the surgeries noted above.

Examination revealed normal vital signs on arrival to the hospital, but he had a documented fever of 102.5° F in the clinic.

General appearance was that of a normal 5-year-old boy in mild distress with painful swelling of the left cheek with erythema (Figures 1 & 2). The wound was still glued closed, and therefore no discharge was seen (Figure 3). He was also found to have a through-and-through injury to his lower lip that was healing well (Figures 4 and 5). The remainder of his examination was otherwise completely normal.

His lab tests revealed a normal CBC and a blood culture is pending.

Later on the day of admission, Plastic Surgery was consulted, who then took him for incision and drainage, revealing a small amount of pus, which revealed no organisms on Gram stain, and culture is pending.

How would you treat pending culture results?

1. Continue oral amoxicillin- clavulanate
2. IV Unasyn (ampicillin + Sulbactam)
3. IV Vancomycin
4. IV Clindamycin + Unasyn

Case Discussion

Your choice may be none of the above, and be perfectly correct, but my choice was “D, IV clindamycin plus Unasyn” (Ampicillin + Sulbactam); the clindamycin for the possibility of methicillin-resistant Staphyloccus aureus and the Unasyn for other human and dog mouth organisms, such as Pasteurella multocida, group A strep, Eikenella corrodens and other anaerobes.

This patient’s culture grew three organisms; (1) Eikenella corrodens, (2) an oxidase-positive, pan-sensitive Gram-negative rod that the lab was unable to speciate and (3) a Neisseria species, which all sounds more like a human bite than a dog bite infection.

It is most likely that this mixed infection represents organisms from both the dog’s mouth and the child’s face skin. In either case, the child improved rapidly after the incision and drainage, and was sent home on Amoxicillin-clavulanate about 36 hours after admission, to follow up in the plastic surgery clinic six days later. At that time, he had no evidence of residual infection, and he was dismissed back to his primary provider.

There are several teaching points with this case:

(1) Wound management in the emergency department – It is widely agreed that primary repair, preferably by a plastic surgeon, is reasonable on bite wounds to the face, if done within the first eight hours. However, many experts recommend using sutures rather than tissue glue for bite wound closure in general, because of the increased risk of infection, to allow for drainage through the sutures in the event that it gets infected. Also, puncture wounds should not be sutured or glued.

(2) Tetanus risk – Following the guidelines from the Infectious Diseases Committee of the AAP (RedBook), as long as the child has had at least three doses of tetanus toxoid and it has been less than five years since the last dose, another dose at this time is not needed.

(3) Rabies risk – As long as the dog is known and the veterinarian can document immunizations and the dog can be watched in quarantine for at least 10 days, rabies prophylaxis (rabies immune globulin and vaccine) is not needed. The issue of “unprovoked” attacks is oftentimes questionable. When thoroughly explored, it usually turns out that the dog was provoked by the child by being too close to the dog’s food dish, getting in to the dog’s face or some other activity that causes the dog to snap at the child. A truly unprovoked attack is one when the dog goes out of its way to get to the child, which does not necessarily mean the dog is rabid but may just be an aggressive dog. A rabid dog will almost always act strange (to those who know him), even in the first few days of rabies, then will become aggressive and unpredictable, biting at anything nearby before dying of respiratory failure. However, having said that, you only get one chance to make the right decision with rabies prophylaxis.

(4) Antimicrobial prophylaxis – Even though the infection turned out to be due to organisms that are sensitive to Amoxicillin -clavulanate, this points out the limitation of prophylaxis in general. It relies on several factors, such as compliance, absorption from the gut, and sensitivity of the organisms contaminating the wound. Even under the best of circumstances, sometimes prophylaxis fails. However, it is generally recommended for all human, cat and dog bites, even though there’s not much evidence for benefit. As a rule, the cat bite is more likely to get infected because of the penetrating nature of the cat bite (Figure 6), as opposed to the dog bite, which is often a tearing or ripping injury (Figure 7). However, the dog bite can result in a puncture-type wound also, leading to infection (Figure 8).

(5) Timing of infection manifestations – As a general rule, Pasteurella multocida and group A strep infections tend to occur very early in these injuries, whereas Staphylococcus aureus and other less common organisms tend to appear a bit later/slower. The child in figure 9 had an infected dog bite within the first 24 hours and grew Pasteurella multocida. She was treated with IV antibiotics for several days and then oral Amoxicillin-clavulanate, with a good outcome (Figure 10) a couple of weeks later. The patient in figure 6 was also seeking care within 24 hours of the cat bite.

Columnist comments

To read just about everything you need to know about bite wound management, including infectious complications, I would recommend starting with Charles M. (Chuck) Ginsburg’s chapter in Nelson Textbook of Pediatrics, 18th edition (2007), chapter 712, pages 2928 – 2931.

Dr. Ginsburg is the Marilyn R. Corrigan Distinguished Chair of Pediatric Research and Associate Dean for Academic Affairs at The University of Texas Southwestern Medical Center in Dallas, Texas. He is also one of my role models (from afar), in that he was the one who really popularized visual diagnosis as a teaching tool. I can still clearly remember seeing him present his series of visual diagnosis cases at the annual National Pediatric Infectious Diseases Seminars (NPIDS) in its early years. It was my honor, many years later, to attempt to do the same at this venerable, springtime meeting, but that was a goal one could only pursue as no one could do it better than Chuck Ginsburg. Unfortunately, after 27 years, the NPIDS became a victim of the times and no longer exists, and I really miss it.

Last month I mentioned how our uniformed colleague, Mark Burnett, is engaged in humanitarian work (in his spare time) in Afghanistan and is collecting old textbooks for use in various civilian Afghan clinics. He has provided another APO address for the Nuristan Provincial Reconstruction Team, which is in serious need of medical books. If you have any recent editions of books that you don’t need, instead of throwing them out, please consider sending them to:

Medical Officer PRT Nuristan (Kalagush) APO AE 09354
or to the other site mentioned last month:
Medical Officer
PRT Kunar (Asadabad)
APO AE 09354

I will share any feedback from Dr. Burnett in future issues.