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Preteen presents with erythema of her right foot
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An 11-year-old female is admitted to the hospital with swelling, pain and erythema of her right foot.
James H. Brien
The history of this problem began 3 days earlier when she was running through her house barefoot, stepping onto a glass aquarium that was lying on its side, crashing through the glass. She had a reflex reaction to jerk her foot up, resulting in a shard of glass to stick into the dorsolateral aspect of her foot. The aquarium had been used for fish and, more recently, to house a guinea pig, and had not been cleaned out. The day after the injury, there was some increased pain and swelling, and she was taken to an urgent care clinic, where she was empirically prescribed trimethoprim-sulfamethoxazole and given a tetanus booster (Tdap). The next day, the presenting complaints had rapidly developed, and she was taken to the children’s hospital ED and admitted.
Examination revealed a healthy-appearing, preteen female with normal vital signs, with swelling, pain and a laceration with mild surrounding erythema, and increased erythema just proximal to the fifth toe of the right foot (Figures 1 and 2).
Images: Brien JH
Her medical history is that of a previously healthy female whose immunizations were up to date (fifth tetanus immunization at age 4 years and 1 month). It was also noted that she had been diagnosed with streptococcal tonsillitis by positive rapid test and would have finished a 10-day course of amoxicillin the day before the accident, but did not take it all.
Plain radiographs were normal, but an MRI reveals enhancement of the head of the fifth metatarsal (Figure 3), several centimeters distal to the puncture wound. Additionally, she had a minor laceration of the tip of the great toe of the same foot (Figure 4).
Examination revealed a healthy-appearing, preteen female with normal vital signs, with swelling, pain and a laceration with mild surrounding erythema, and increased erythema just proximal to the fifth toe of the right foot (Figures 1 and 2). Plain radiographs were normal, but an MRI reveals enhancement of the head of the fifth metatarsal (Figure 3), several centimeters distal to the puncture wound. Radiology read the MRI as being consistent with osteomyelitis of the head of the fifth metatarsal. Additionally, she had a minor laceration of the tip of the great toe of the same foot (Figure 4). Lab tests included a normal CBC and an elevated C-reactive protein at 20.2. A blood culture was negative. Since there was no expressible discharge, no wound culture was done.
What’s Your Diagnosis?
A. Staphylococcus aureus
B. Pseudomonas aeruginosa
C. Group A strep
D. Mycobacterium marinum
Case Discussion
I picked C, group A strep. However, since no organism was recovered, your guess is as good as mine. But using some logical reasoning, we can probably rule out P. aeruginosa for a couple of reasons; the infection occurred too soon after the puncture wound and also, these infections are usually associated with puncture wounds involving the wearing of sneakers, such stepping on a nail. These infections typically manifest themselves about a week later, and although painful, may appear to have only some subtle, diffuse erythema (Figure 5), with little more than a puncture wound visible (Figure 6). M. marinum is one of the non-tuberculosis mycobacteria that usually cause infections as a result of an injury in water that is contaminated with the organism. The aquarium mentioned in the history may have been contaminated with some unusual organisms, but since it was dry, M. marinum would probably not be among them. This leaves S. aureus or group A strep (GAS). In my opinion, GAS is more likely for the speed of onset and progression; usually within 24 to 36 hours. Also, there’s evidence of the patient being at least colonized in the respiratory tract with GAS a couple of weeks before the accident. Except for this, S. aureus would be statistically most likely. S. aureus infections tend to take a couple of days or more to develop (Figure 7, S. aureus infection several days after a splinter puncture wound). However, other, less common organisms could also be considered; just not as likely. Since the last occupant of the aquarium was a guinea pig, one might think of Pasteurella multocida, which also results in a rapid-onset infection like GAS. However, that organism cannot survive the drying effect of being outside the mouth of the host animal more than about 24 hours. These infections may appear to have only some subtle, diffuse erythema (Figure 5), with little more than a puncture wound visible (Figure 6).
These infections typically manifest themselves about a week later, and although painful, may appear to have only some subtle, diffuse erythema (Figure 5), with little more than a puncture wound visible (Figure 6).
Figure 7 is an S. aureus infection several days after a splinter puncture wound. A narrow shard of glass entered the foot at the wound site when the patient jerked it in an upward direction, as described above; penetrating at just the correct angle and distance, to prick the head of the bone, causing the osteomyelitis (Figure 8).
One might ask, how osteomyelitis of the head of the fifth metatarsal occurred, when the apparent port-of-entry was several centimeters proximal to that area. This factor resulted in some spirited debate about the MRI reading; some thinking perhaps it was a false positive. However, the MRI is usually right. The “Brien Theory” (not shared by all), is that a narrow shard of glass entered the foot at the wound site when the patient jerked it in an upward direction, as described above; penetrating at just the correct angle and distance, to prick the head of the bone, causing the osteomyelitis (Figure 8). Since this injury happened so fast, the exact mechanism may never be explained. However, she had a good, although somewhat slow, response to IV clindamycin plus ceftriaxone via a PICC line for 2 weeks before she developed a reaction to the ceftriaxone. She then finished a total of 5 weeks of IV clindamycin followed by 2 weeks of oral therapy, with an excellent outcome with 2 years of follow-up. Figure 7 is an S. aureus infection several days after a splinter puncture wound. A narrow shard of glass entered the foot at the wound site when the patient jerked it in an upward direction, as described above; penetrating at just the correct angle and distance, to prick the head of the bone, causing the osteomyelitis (Figure 8).
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James H. Brien, DO, is with the department of infectious diseases at McLane Children’s Hospital, Baylor Scott & White Health, Texas A&M College of Medicine in Temple, Texas. He is also a member of the Infectious Diseases in Children Editorial Board. Brien can be reached at: jhbrien@aol.com.
Disclosure: Brien reports no relevant financial disclosures.