December 2003

A 10-year-old female was admitted to the hospital last summer for evaluation and treatment of a swollen, painful right hand lasting three days and worsening. Additional history revealed a minor laceration of her hand was sustained while climbing up a swimming pool slide ladder about one week prior to admission (four days prior to onset of symptoms). She recalled further aggravating the injury later while wrestling with her brother. She was seen in the clinic at the onset of pain with a normal x-ray of the injured hand. However, with the onset of more pain, swelling and erythema, accompanied by some nausea and fever, she was reevaluated and admitted.

Her past medical history is positive for attention deficit-hyperactivity disorder (ADHD), but otherwise unremarkable. Her immunization history is uncertain. She has no known allergies and does not recall being bitten on the hand by any insect or animal.

Examination revealed a painful, swollen and erythematous right hand with a blistering lesion on the thenar eminence as shown in figures 1–4. There also was some erythema streaking up the medial aspect of the arm with some tenderness in the axillary area. The rest of her examination was that of a normal 10-year-old female. Lab tests were positive for elevated C-reactive protein, with a normal complete blood count. The patient was taken to the operating room for incision and drainage with material sent for stains and culture.

What is most likely found?

1. Acid-fast bacilli
2. Gram-negative rods
3. Gram-positive cocci
4. Septate hyphae

Answer

Gram’s stain of material drained from the lesion revealed gram-positive cocci, and culture grew Streptococcus pyogenes (group A strep). Upon admission, she was initially treated with intravenous clindamycin plus gentamicin pending cultures, and given a tetanus booster. The temptation to come up with something exotic because of the association with being in or around a swimming pool may lead one away from the most likely cause. Even though pools and especially hot tubs are occasionally associated with infections caused by Pseudomonas aeruginosa (a gram-negative rod), the most likely cause of a soft tissue infection with an abscess remains gram-positive cocci. This will usually be Staphylococcus aureus, followed by group A strep (GAS).

It is my experience that these soft tissue infections caused by GAS are more serious and rapidly progressive than most other organisms. And why should that come as a surprise? Throughout recorded medical history, S. pyogenes has been associated with severe suppurative infectious complications such as necrotizing fasciitis in wounded soldiers during the civil war, life threatening “scarlet fever” (sepsis or streptococcal toxic shock syndrome?) and puerperal fever during the 19th century. Much has been learned about the virulence of this organism over the decades that help explain its suppurative and non-suppurative complications. As a bacterium, it is fairly unique in its ability to cause the non-suppurative complications such as rheumatic fever and acute glomerulonephritis. But these are topics for another day. The suppurative complications, like the child presented had, seemed to almost disappear in the mid-20th century, with much credit given to the widespread use of the newly discovered penicillin and other antimicrobials, as well as improved public health and hygiene. However, the incidence of severe, invasive disease actually began to dramatically decline in the latter part of the 19th century, well in advance of these more modern developments. Not to diminish the important role that antimicrobials have played in the ability to treat these infections, it is likely that natural changes in the geography and virulence of GAS played a large part in this observation.

GAS is usually “typed” using the M protein, which, along with lipoteichoic acid, makes up the fimbriae, which are the hair-like structures that gives the bacterium a fuzz-like appearance of the outer surface. These structures are responsible for the ability of the organism to attach to the epithelial cell, which is the first step in the infection process. There have been over 100 M-types identified, with some types identified as being associated with more serious infections than others. There are many other virulence factors in the form of various enzymes, hemolysins, bacteriocins and various toxins that help GAS live up to its name, S. pyogenes (Greek for the formation of pus). GAS pneumonia is a good example of its pyogenic potential. Every case of proven GAS pneumonia that I have been involved with over the years (since the mid-80’s), had severe empyema associated with it (figures 5-6), usually requiring surgical debridement (figure 7-8) before resolving. It apparently was GAS pneumonia with sepsis that resulted in the death of Muppet creator, Jim Henson in 1990.

For those interested in reading all you ever wanted to know about this fascinating organism, I would recommend Edward Kaplan and Michael Gerber’s chapter 87 in the new, 5th edition of Feigin and Cherry’s Textbook of Pediatric Infectious Diseases that just came out. This new edition has Gail Demmler and Sheldon Kaplan, both of Baylor College of Medicine, added as editors. This text remains the most comprehensive reference on the broad subject of pediatric infectious diseases, and a must for anyone who needs an in-depth description of any topic in this field.

Due to the severity of the infection, the child presented was soon treated with a combination of clindamycin and penicillin when the Gram’s stain results were known (indicating either staph or strep), to avoid the “Eagle effect” (Harry Eagle, American Journal of Medicine. 1952;13:389-399). This phenomenon has been addressed in this column before, but essentially, this describes a situation where in the presence of a high inoculum of organisms, GAS moves into a prolonged stationary phase of replication with associated decrease in penicillin-binding proteins. This makes ß-lactam antibiotics less effective, whereas clindamycin acts at the 50S ribosomal subunits, independently of the organism’s phase of replication. Therefore, in cases like this, until the cause is known and control of the infection is obtained, we frequently use this combination to treat GAS via these two mechanisms, plus the clindamycin is not a bad anti-staph antibiotic pending culture results. Gentamicin was used initially because of concern over the possibility of gram-negatives picked up in the pool.

There is also an uncommon soft tissue, granulomatous infection caused by Mycobacterium marinum, “swimming pool granuloma,” that can be contracted by scraping the skin in a pool of water contaminated with this acid-fast, non-tuberculous mycobacterium. It obviously would not fit the patient described above.

Lastly, I threw in septate hyphae to represent fungal causes, like aspergillosis. I have seen some ugly cutaneous aspergillosis in severely immunocompromised cancer patients, but again, that did not fit the history, and I just needed something to put in choice #4. Sorry.

I would like to wish you all a happy holiday season and a safe and prosperous New Year. And again, please remember our uniformed-services men and women serving in Iraq, Afghanistan, and other hostile and remote places around the world during this joyful, yet dangerous season. Please participate in your local gift or care package program for these brave men and women. You cannot imagine how much it means to receive a simple gift when you’re out in the middle of nowhere with nothing.

For more information:

• James H. Brien, DO, Pediatric Infectious Disease, Scott and White’s Children’s Health Center and Associate Professor of Pediatrics, Texas A&M University, College of Medicine, Temple, Texas. E-mail: jhbrien@aol.com.