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Pediatric Update

 
Summer 2005

Antibiotic-resistant Infections On the Rise in the Community

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Significantly more children are becoming seriously ill iwth community-acquired staphylococcal infections.

The growing incidence of infections that are resistant to antibiotics has important implications for pediatric practice, both in the hospital and in the community. In the past year, approximately a dozen reports have noted a dramatic increase in the number of previously healthy children infected with highly invasive and resistant community acquired methicillin-resistant Staphylococcus aureus (CA-MRSA). “This is not a subtle change; it’s a dramatic change that’s affecting pediatricians’ practices in Southern California and across the country,” says Paul Krogstad, M.D., a pediatric infectious disease specialist at Mattel Children’s Hospital at UCLA.

“The problem is more than just resistance to antimicrobial agents. These community-acquired staphylococcal infections are more likely to spread to the bones and joints and to cause necrotizing pneumonia and sepsis. Moreover, these are infections acquired in the community, and not from bacteria picked up in the hospital.”

 A recent study involving the Centers for Disease Control and Prevention found that approximately one in five infections were being acquired in the community, with no apparent links to healthcare settings. Nearly one in four cases was serious enough to require hospitalization. Another study reports that CA-MRSA has acquired the ability to cause necrotizing fasciitis—a condition not previously associated with staphylococci.

More than a dozen cases of necrotizing fasciitis caused by methicillin-resistant Staphylococcus aureus were reported in the Los Angeles area, all of which required surgery and most of which put patients in intensive care. “Children under the age of 2 are at particularly high risk for acquiring these dangerous infections, which can’t be treated with the antibiotics pediatricians are used to prescribing for common skin infections,” notes Dr. Krogstad.

A highly resistant clone of staphylococci that also expresses a toxin known as Panton-Valentine leukocidin has emerged in the United States and is “the worst version of staphylococci we have seen in decades,” says Dr. Krogstad. Pediatricians should be on the lookout for patients with recurrent skin and soft-tissue infections and consider decolonization measures in certain cases. “The organism is often harbored in the anterior nares,” Dr. Krogstad notes.“Culturing can identify colonization, and then a number of steps can be taken to break this cycle of infection.”

Steps include determining if other family members have also had recurrent infections, potentially screening all family members; using bactericidal soaps for approximately two weeks; simultaneously washing all bedding; and employing an antibacterial ointment (mupirocin) in the anterior nares.

Surgery has become an increasingly important component of treatment. Resistant organisms cause an estimated 50 percent to 60 percent of the 2 million hospital-acquired infections each year. Bloodstream infections cause half of the deaths in infants who require hospitalization in neonatal intensive care units for more than two weeks.

The leading cause of infection in hospitals is Staphylococcus epidermidis. “This is an organism normally present on the skin of patients and healthcare providers, but patients who are immunocompromised or who have indwelling or implanted foreign polymer bodies are at high risk for infection caused by the organism,” says Vladana Milisavljevic, M.D., UCLA neonatologist. Thus, premature infants who require central catheter lines are at particularly high risk, she notes, adding that the organisms acquired during hospitalization are likely to be multiresistant to antibiotics.

Dr. Milisavljevic is conducting research to determine what makes the organism normally habitant on the skin become a pathogen once it gets into the bloodstream of immunocompromised babies. She says that one of the most important pathogenic qualities of Staphylococcus epidermidis is its production of a biofilm that coats plastic polymer devices, preventing antibiotics from penetrating.

Recently, she has studied the effect of alcohol on such biofilm production and has found that low percentages of alcohol added to certain strains of Staphylococcus epidermidis can trigger or enhance biofilm production, resulting in more pathogenic bacteria. “This is worrisome, because alcoholbased disinfectants are the standard in intensive care units, and their use in the community is increasing,” she says.

For highly resistant staphylococci as well as highly resistant pneumococci—which, unlike the staphylococcal problem, is a development that appears to have resulted from overuse of antimicrobials— the pipeline of effective new antibiotics is limited. The problem of antimicrobial overuse has been widely publicized. “When pediatricians are treating infections that they think are caused by bacteria, it’s important not to start with the big guns—the broad-spectrum antibiotics—because the more we use them, the more we allow bacteria to learn how to resist them,” Dr. Milisavljevic explains. Adds Dr. Krogstad: “We finished the 20th century with many antimicrobial agents but now face the possibility that a lot of them will be ineffective in the next 10 to 20 years unless we use them more judiciously.”

The results of surveys and focus groups of pediatricians have suggested that over-prescription of antibiotics, particularly for upper-respiratory infections, results from their feeling pressured by parents. “We’re living in a consumerist medical environment, and there is a great deal of concern that if you don’t give people what they want, they will just go see someone else,” says Rita Mangione-Smith, M.D., UCLA pediatrician.

Antibiotics are being over-prescribed for bacterial infections—and even for viral causes of childhood bronchitis and other infections for which they are of no use. Where antibiotics are indicated—most commonly for ear infections—first-line drugs such as amoxicillin are too often being skipped in favor of broader-spectrum drugs, a trend that also leads to greater resistance.

In recent years, Dr. Mangione Smith and colleagues have sought to empirically test the assumption that parent pressure drives inappropriate antimicrobial prescription by pediatricians. Through videotaping of office visits and post-visit surveys of parents in two private pediatric practices, they explored how preferences for antibiotics were communicated by parents and whether the physicians were able to convey why the drugs were not being prescribed in a way that would leave the parents satisfied. They found that among parents whose children were not prescribed antibiotics, those who were offered a contingency plan—the possibility of antibiotics being prescribed if their child failed to get better soon—were significantly more satisfied.

“If the child looks very sick and you’re not sure whether or not it’s a bacterial illness but you’re uncomfortable sending him or her home without starting something, then you need to prescribe medication,” says Dr. Mangione-Smith. But she recommends that pediatricians offer the contingency for other cases in which they feel strongly that the child has a viral condition. “We found that even if antibiotics were not clinically indicated, giving a treatment plan to help relieve symptoms such as cough or ear pain and telling the parent that an antibiotic will be considered if the child is not getting any better in 48 hours results in a satisfied parent most of the time,” Dr. Mangione-Smith explains.





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