August 2004

An 8-month-old male infant is admitted to the hospital for the evaluation and treatment of a red, swollen and painful left breast. It began a few days earlier as a small red bump and progressively got larger. There is no history of injury or known insect bites. He has otherwise been healthy. Nothing like this has ever happened before. His immunizations are up to date.

Examination revealed a normal-appearing male infant with a fever of 102° F and an area of fluctuant swelling and erythema of the left breast measuring 4 by 6 cm with a small sore just adjacent to the nipple (Figures 1-2). There were no other positive findings. A blood culture obtained is pending.

Answer

This is obviously a case of mastitis, or a soft-tissue infection with abscess formation of the breast tissue and/or the surrounding tissues. In either case, the most common cause by far is Staphylococcus aureus (C). Occasionally it may be caused by gram-negative or mixed organisms, but staph should always be considered in the decision to treat.

As noted, it appeared that there was a break in the skin that served as a port of entry for the causative organism.

Now that we are well into the summer, with lots of biting insect activity, soft-tissue infections are on the rise. Even though the history was negative for “known” insect bites, unless a child lives in a bubble, they ALL are receiving insect bites in the summer months. We have had an unusually wet spring and summer in Texas, so mosquitoes are abundant, and all it takes is one bite with some accompanying itching along with colonization of the skin or fingers to set the stage for one of these infections.

Therapy

Appropriate therapy should include an anti-staph antibiotic along with surgical drainage, if fluctuant. Aggressive medical and surgical therapy is very important, especially in the female patient, to avoid possible damage to the breast tissue, resulting in abnormal breast development later in life.

Most experts also recommend obtaining a blood culture, especially if the patient is febrile, as there is a chance of associated bacteremia. Also, one should obviously culture any pus obtained from the abscess as it is drained. This is very important since therapy may need to be changed if it is a resistant organism, or one that was unexpected.

I usually recommend starting treatment with a reliable anti-staph antibiotic, but in a neonate, I would probably add an aminoglycoside as well, pending cultures, because of the increased chance of a gram-negative organism being recovered. With the increasing recovery of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA), empiric anti-staph therapy may need to be something other than nafcillin or a cephalosporin. Some are starting therapy with clindamycin pending culture results, since most CA-MRSA are sensitive.

However, if it is an erythromycin-resistant strain of CA-MRSA, one should ask the microbiology lab to perform a D-test, to rule out inducible resistance to clindamycin. An excellent review of this phenomenon can be found in The Pediatric Infectious Disease Journal (2002; 21:530-534). If there is no inducible resistance, then it should be safe to continue with clindamycin, either IV or oral, when the patient is improved.

However, if inducible resistance is demonstrated in the lab, the best IV choice is probably vancomycin. One may consider trimethoprim-sulfamethoxazole (TMP-SMX) as an alternate if the strain is shown to be sensitive. If the MRSA is resistant to all the oral antibiotics, one may consider using linezolid (Zyvox, Pfizer) orally at a dose of 20 to 30 mg/kg/day in two or three divided doses.

However, this should not be used for simple soft-tissue infections if there is an alternative. This antibiotic should normally be reserved for serious infections caused by vancomycin-resistant organisms. To read more about linezolid, I recommend the review paper by Jay Lieberman in the December 2003 issue of The Pediatric Infectious Disease Journal (22[12]:1143-1151).

Regardless of the antibiotic choice, I cannot overemphasize the importance of good, thorough drainage. If this is done well, with all loculations opened, and a drain is left in place, the patient will likely get better even on the wrong antibiotic. To demonstrate this point, Figures 3-5 show a different patient with mastitis due to CA-MRSA, who was drained and sent home on clindamycin, but had a D-test come back positive for inducible resistance. However, when the patient was recalled for early follow-up, she was essentially well anyway, demonstrating the effect of surgical drainage or perhaps the effectiveness of clindamycin even if inducible resistance is shown in the lab. We changed therapy to trimethoprim-sulfamethoxazole anyway.

Lactobacillus mastophrophilus was just made up, although it sounds appropriate.

West Nile

Lastly, remember to think of mosquito-borne infections like West Nile virus infection or other arbovirus diseases when evaluating patients with enceph-alopathy this time of year. There are “hot spots” around the country where these things are more common. Arizona and California are leading the country by far in human West Nile infections. There is an entire West Nile home page at the CDC Web site. There’s a map of activity by human and by avian, animal or mosquito infection. I would recommend visiting that site for all you need to know about West Nile disease.

Comment: I hope you are not tiring of my monthly appeal for our military, but if you are, simply stop reading the comments at the end of this column. However, if you are interested in getting involved in supporting our deployed military personnel, whether they are pediatricians or privates, I would suggest getting in touch with one of the many support groups that exist for this purpose.

They can be found on the Internet. You can just “Google” “soldier support groups” and you will get thousands of hits. Some of these groups may be fraudulent, but with a little research, you can figure out the legitimate ones to help get involved. Better yet, if you live near a military installation, simply visit their Web site or go to their visitor center in person, where you can easily find out how to get involved. Your local VFW, American Legion and other similar organizations can also help.

Another excellent Web site for obtaining information about Army unit or soldier support or sponsorship is the Association of the United States Army (AUSA) at www.ausa.org. One can easily link to Air Force and Navy-Marine Corps support sites as well from this Web site. All it takes is an APO address of a unit or individual, and it costs the same as it would to send a package or envelope anywhere in the United States. Believe me, these young (and not-so-young) men and women strongly appreciate receiving letters and packages from home. It’s not exactly like hearing from family, but there’s something special about hearing from people you don’t know.

It’s a tremendous morale boost. I recall receiving a “Dear Soldier” shoebox full of candy canes and letters from a class of elementary school children when I was deployed in 1991. I’m not a very emotional guy, but this came at a time of high stress, and it brought tears to my eyes to think that we had the support of all these people. I sat down and wrote a note back to each one of those kids and their teacher, with a sprinkle of sand in each envelope. Several kept in touch for a good while longer. It really meant a lot to me, and I think I did a better job as a result.

Regardless of your political stand on this war, we should all remain unwaveringly supportive of these brave men and women who are dying virtually every day for this cause. Let’s hope the mission is successful and that it ends soon. Please keep in touch. — James H. Brien, DO

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.