by Al Kline DPM¹

Podiatry Internet Journal 2 (1):3

Osteomyelitis is a challenging condition to treat in the foot. Although staphylococcal osteomyelitis has been more commonly reported, there appears to be an increasing emergence of streptococcal infections reported in the literature. Streptococcal infections can be much more virulent in their presentation and more difficult to treat.  A case is presented describing streptococcal infection of bone in the fifth metatarsal head. A panel discussion includes current concepts on metatarsal resection and the appropriate time to close a surgical wound in the presence of osteomyelitis. Conclusions derived from this case study would support leaving a surgical wound open in the presence of osteomyelitis, especially in the presence of streptococcal organisms.

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Osteomyelitis of the foot can often result in diabetic amputation. Eighty-five percent of all lower extremity amputations in patients with diabetes are preceded by foot ulcerations.[1] Most diabetic foot infections are caused by staphylococcal organisms. In fact, in recent years, we have seen a resurgence in Methicillin Resistant Staphylococcus aureus or MRSA in diabetic foot infections. These infections have been hospital acquired in most cases, but a recent report has suggested an increased in community acquired MRSA or CA-MRSA.[2] The diagnosis of osteomyelitis has spurred debate as to its best clinical and diagnostic determination. Up to two-thirds of patients with diabetic foot ulcers may have osteomyelitis.[3] In a landmark study in 1995, the ability to probe directly to bone had a high positive predictive value for osteomyelitis ( up to 89 percent).[4] However, in cases where sinus infections or smaller ulcers are noted, this may be a more difficult determining factor. In fact, in more recent studies, the positive predictive value of probing to bone has been shown to be around 54-57 percent with actual prevalence of osteomyelitis as low as 20 percent. [5] Radiographic determination is possible, but is usually associated with chronic osteomyelitis. MRI is still considered the gold standard at this writing for the early diagnosis of osteomyelitis. When osteomyelitis is suspected, MRI has a sensitivity and specificity of greater than 90 percent.[6] What about that remaining 10 percent?   This shows that the diagnosis of osteomyelitis should be based, in part, on clinical presentation and degree of clinical suspicion. There have been numerous reports of streptococcal osteomyelitis in the literature, but less information on streptococcal osteomyelitis as it affects the diabetic patient with a foot ulcer. In 1995, Lavery, et al, reported up to 61 percent streptococcal infections were associated with neuropathic, diabetic ulcers.[7]   Forty-seven percent of infections in the same study were stphylococcal.  

Case Report

In this case presentation, a 63 year old diabetic male presents with a small sinus tract and ulceration to the left fifth metatarsophalangeal joint. (Fig 1). The patient is very active and recently returned from a hunting trip in Africa, where he began to notice an increased swelling and redness of his foot the previous week. The patient has had a previous right 2nd digital amputation 5 years ago due to osteomyelitis. The patient initiated self treatment including daily cleansing of the foot and taking Tylenol for fever. He presented to us febrile and was admitted promptly to the hospital. He was placed on IV Primaxin and scheduled for local incision and drainage with partial fifth metatarsal head resection. His initial laboratory reports revealed a white count of 19,800. His admitting glucose level was 61 mg/dl. He was febrile with a 101 temperature.

 

FIGURE 1   Initial presentation reveals localized cellulitis with a plantar lateral sinus tract.

In his initial presentation, there was erythema and local edema with a plantar sinus tract. Manual palpation of this area revealed very little drainage from the sinus tract. His radiographic evaluation revealed a region of sequestered bone along the medial 5th metatarsal head. (Fig 2). This indicated a long-standing, chronic infection to the metatarsal head consistant with chronic osteomyelitis. Once the patient was admitted to the hospital setting, he was scheduled for emergency incision and drainage with partial 5th metatarsal head resection.

FIGURE 2   Radiograph reveals a small region of sequestered bone consistant with chronic osetomyelitis.

Surgical Technique

In surgery, the patient underwent a laterally placed incision away from the sinus tract.  (Fig 3).  Once the capsule was incised,  purulent drainage was identified and cultured.  The sinus tract was probed which showed direct communication with the fifth metatarsal joint.  The metatatarsal head was then removed.  The entire site was then lavaged with antibiotic irrigation using a pulsatile irrigation unit.  Care was taken to irrigate the sinus tract thoroughly.  The sinus tract was then packed and the incision site was then closed and dressed.  Monofilament suture was used to close the deep layers and skin.

  

  

FIGURE 3   Initial incision is made dorsolateral to the 5^th metatarsal head.  When entering the joint, purulent drainage was identified.  This was cultured and the metatarsal head is then removed.  The plantar sinus tract was identified with direct communication to the joint capsule.  The entire surgical site is lavaged with 3L normal saline and the sinus tract is packed plantarly.  

Postoperative Course and Treatment

The patient’s surgical site was observed daily. His white count decreased from 19,800 to 11,000. His initial surgical cultures revealed 1+ white blood cells with 1+ coagulase negative staph species. On day 2, an amended report revealed Streptococcus agalactiae, Group-B as the primary organism. The packing was removed. In the first three days, the surgical site began to deteriorate and discolor. The sinus tract appeared dry, although subcutaneous hemorrhage was seen. It was determined at that time to open the wound and re-irrigate the wound at bedside. He also started whirlpool and daily packing with wet to dry saline gauze. (Fig 4). Six days after surgery, the surgical site stabilized and he was discharged on home oral antibiotics including oral Augmentin 1000mg BID and Clindamycin 300mg TID. Daily packing and wound care was initiated on an outpatient basis.

 

 

FIGURE 4   Initial incision is made dorsolateral to the 5^th metatarsal head.  When entering the joint, purulent drainage was identified.  This was cultured and the metatarsal head is then removed.  The plantar sinus tract was identified with direct communication to the joint capsule.  The entire surgical site is lavaged with 3L normal saline and the sinus tract is packed plantarly.

Nine days after his initial surgery, the skin showed signs of necrosis. (Fig 5). The patient was neuropathic, so sharp debridment was initiated in the office of all visible necrotic tissue. It is interesting to note that the necrosis followed the direction of the sinus tract infection. Upon debridement, sinus tract infection was still noted.

 

FIGURE 5   Nice days after surgery, further debridement was initiated with continued local wound care. 

1 week after debridement and 16 days after his initial surgery, the surgical site shows deep granulation and tissue healing. (Fig 6). Simple local sharp debridement and wet to dry saline gauze packing was continued.

 

FIGURE 6   Sixteen days after surgery, the infection is now resolving on aggressive antibiotic treatment and deep granulation tissue is forming. 

28 days (Fig 7: A,B) and 40 days (Fig 7: C,D) after initial surgery, the surgical site showed rapid granulation, contracture and secondary closure of the wound. He still remains on penicillin antibiotics and continues to use saline gauze dressings. Packing of the wound discontinued.

 

 

FIGURE 7   28 days (A,B) and 40 days (C,D) the surgical site is ‘clean’ without any infection and beginning to contract.  Deep granulation tissue has now formed.  This will set the stage for further contracture and epithelialization of the wound site.

6 weeks after surgery, hypertrophic granulation tissue was debrided and silver nitrate was applied to decrease granular tissue in the wound. 8 weeks after surgery, the region is now almost completely healed with no signs of residual infection. (Fig 8).

 

 

FIGURE 8   6 weeks (A,B) and 8 weeks (C,D) after surgery, the surgical site is all but closed.  A happy ending for a most virulent, serious streptococcal infection.

Discussion

This case highlights the aggressiveness of streptococcal infection in the foot. No further culturing was performed after deep surgical cultures and the patient was maintained on penicillin antibiotics for a 6 week duration after the initial surgery. Group A streptococcal infections (GAS) are most associated with necrotizing fasciitis.[8]  In recent years, Group B streptococcal infections (GAB) have been implicated in necrotizing infections [9]. Treatment regimes now recommend combination beta lactam penicillins and clindamycin . [9]. This treatment combination has been shown to be better than using penecillins alone.
This case also opens a debate concerning the surgical approach involving sinus tract infections in the presence of osteomyelitis.  Surgical biopsy,  including open surgical culture biopsy away from the ulcer or sinus tract, has been described in previous papers. Comparing the microbioligical results of needle puncture versus superficial swab results in infected diabetic foot ulcers with osteomyelitis, Kessler, et al, revealed no complications using needle biopsy technique and revealed one or two bacterial isolates in two-thirds of the diabetics studied.[10] However, Perry, et al, showed failure of superficial swabbing and needle biopsy in 60 patients who had post-traumatic or postoperative osteomyelitis. His results revealed tissue is better obtained for culture during operative debridement in order to identify all pathogenic organisms.[11] Culturing sinus tract infections is unnecessary and will reveal mixed and superficial organisms. It is generally accepted that there is very little correlation between sinus tract cultures and bone cultures, unless the pathogen is primarily Staphylococcus aureus.[12] In this case, operative biopsy and removal of the metatarsal head was indicated;  however, a case could be made in hind-sight as to whether incision and drainage of the sinus tract and leaving the wound open would have been a ‘better’ approach? I have personally opened, incised and drained many diabetic infections involving staphylococcal osteomyelitis and closed the wound after thorough debridement of bone and soft tissue without complication. In this case, it appears closing a wound in the presence of streptococcal infection is contraindicated and can lead to aggressive necrotizing recalcitrant infection.

Panel Discussion

This case was presented to the editorial panel of the Podiatry Internet Journal for additional insight concerning surgical and antibiotic treatment.

PIJ: What are your thoughts on the surgical and medical treatment of osteomyelitis.

Bradely Bakotic, DPM,DO:   Radiographs, in conjunction with the appropriate clinical history allows for the PRESUMPTIVE diagnosis of osteomyelitis, and not the definitive diagnosis. Histopathology, in this context, is relatively inexpensive and allows for a definitive diagnosis, while ruling out the possibility of mimics such as primary/metastatic malignancy, locally aggressive tumors (GCT), metabolic disease (i.e., gout), and the rare occurence of chronic osteomyelitis resulting in the development of a superimposed well-differentiated squamous cell carcinoma. We see several of these pitfalls arise with some degree of frequency in our pathology practice.

Mark A. Hardy, DPM, FACFAS: I agree with Brad’s premise of ruling out other “bad actors” or mimics. With that said, my approach would most likely consist of metatarsal head resection and pulse lavage. I would take a clean margin and send it to pathology along with the grossly diseased bone to ensure that appropriate resection was performed. I also use antibiotic beads , frequently,  to place into the resected areas. Depending upon the amount of bone resected, one may also consider syndactylization of the 4-5 toes to prevent future ulceration and complications with the 5th toe. As to when to leave the wound open versus closed, I don’t know that I have a well defined protocol here. Generally, if it is a small well-contained abscess or infection, and I have taken care to ensure appropriate debridement in all directions – especially proximally, then I may close the wound primarily. In contrast, if I am presented with a more fulminant or aggressive infection, my surgical approach is unvaried, but I will choose another form of wound closure such as delayed primary, closure by secondary intention, or grafting as appropriate.

Luke Cicchinelli, DPM, FACFAS: I will perform metatarsal head resections if osteomyelitis is diagnosed. I will then pack the site open if there is acute osteomyelitis and drainage. If the ulcer is chronic, I would close. However, in this case, I would pack through the plantar ulcer for 3-5 days postop and use a dorsal incisional approach. I never close completely if there is any question about persistent infection.

PIJ: What are your thoughts on the treatment of staphylococcal osteomyelitis versus streptococcal osteomyelitis.

Mark A. Hardy, DPM, FACFAS: I don’t know that it would change my treatment protocol, other than with my antibiotic selection as dictated by my C&S results.

Warren Joseph, DPM: Frankly, there is little difference in my approach between Staphylococcal and Streptococcal osteomyelitis. First, there has to be a correct diagnosis. Pure streptococcal osteomyelitis is rare. I can’t remember the last case of it. Usually, at least, some staph is mixed in. In your case there was coagulase negative staph which may or may not have been a pathogen. Also, it is rare for an antibiotic that works against staph to not work against strep also. In fact, off the top of my head, I can not think of one. So, any antibiotic I would normally give for a staph osteo can be used in a strep osteo. Conversely, there are only a few antibiotics that work against strep and not staph. Natural penicillins (Pen VK, or Pen G) or aminopenicillins (ampicillin and amoxacillin) come to mind. Yes, these are effective against strep but need to be given very frequently, with the exception of amoxicillin, and are thus relatively inconvenient. Why not just use an antibiotic that can be used against both organisms and can be given less frequently? In your case, first Primaxin, then Augmentin and clindamycin were given. As noted above, all of these work against both staph and strep. Finally, you need to differentiate WHICH strep you are talking about. There are subtle differences between groups A,B, G, etc. In your case, group B was cultured , which is the most common that is seen in diabetic foot infections. Fortunately, there are not that many issues with resistance or tolerance of this organism to antibiotics.

Conclusions

This case describes the virulence associated with Group B Streptococcal infections as it relates to the foot. In the rare case of streptococcal osteomyelitis, it is apparent that open packing of the wound is indicated and closure should be avoided. This is true even in cases where the incision is placed away from a sinus or ulcer in an attempt to gain ‘clean’ entrance to a wound. In the presence of sinus tract infections, it is also good practice to open the sinus tract and pack this region as well. It appears that as bacteria become more virulent and resistant to antibiotic therapy, indications to close a wound in any form of infection may now be contraindicated. Fortunately, this case resulted in a favorable outcome due to the aggressive opening of the wound and removal of nonviable tissue. Once the pathogen was identified, prompt use of antibiotics bacteriocidal to the organism helped to combat this infection. Streptococcal infections, in general, are necrotizing to the tissues. So, even in cases of open packing of streptococcal infections, additional surgical debridement may be necessary.

References

1. Boulton, A., Kirsner, R.S., Vileikyte, L. Neuropathic Diabetic Foot Ulcers The New England Journal of Medicine, 351: 48-55, July 2004.
2. Hawkes, M. et al Communit-associated MRSA: Superbug at our doorstep, Canadian Medical Association Journal, 176 (1), Janurary 2007.
3. Newman, L.G. et al Unsuspecting Osteomyelitis in Diabetic Foot Ulcers: Diagnosis and Monitoring by Leukocyte Scanning with Indium in 111 Oxyquinoline. JAMA 266:1246-1251, 1991.
4. Grayson, M.L. et al Probing to Bone in Infected Pedal ulcers: A clinical sign of underlying Osteomyelitis in Diabetic Patients. JAMA 273: 721-723, 1995.
5. Steinberg, S., Joseph, W. Point-Counterpoint: Probe to Bone: Is it the best test for osteomyelitis? Podiatry Today, 20:1, January 2007.
6. Craig, JG et al Osteomyelitis of the Diabetic Foot: MR Imaging Pathological Correlation. Radiology 203:849-855, 1997.
7. Lavery, L. et al Microbiology of Osteomeylitis in Diabetic Foot Infections. JFAS, 34: 1, 61-64, 1995.
8. Wong, C. et al Necrotizing fasciitis: clinical presentation, microbiology and determinants of mortality. JBJS 85A, 2003.
9. Wong, C. Kurup, D. Group B Streptococcus necrotizing fasciitis: an emerging disease? Eur J Clin Microbiol Infect Dis 23: 573-575, 2004.
10. Kessler, L. et al Comparison of microbiological results of needle puncture vs. superficial swab in infected diabetic foot ulcer with osteomyelitis Diabetic Medicine, 23, 99-102, 2005.
11. Clayton, P. et al Accuracy of Culture of Material from Swabbing of the Superficial Aspect of the Wound and Needle Biopsy in Preoprerative Assessment of Osteomyelitis. JBJS, 73-A, No.5, June 1991.
12. Armstrong, D.G. et al Current Concepts in Culturing and Treating Infected Wounds. Podiatry Today, Volume 18, Issue 12-A, pages 10-12, December, 2005.

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Address correspondence to:  Al Kline, DPM  3130 South Alameda, Corpus Christi, Texas, 78404.   E-mail: Al@Kline.net.¹Private practice, podiatry staff Doctors Regional Medical Center, Corpus Christi, Texas  78411.

© Podiatry Internet Journal , 2007 

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