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Children in day-care centers are at increased risk for colonization and invasive infection with multidrug-resistant Streptococcus pneumoniae, but a new vaccine that could protect them is in short supply, reports the Centers for Disease Control and Prevention (CDC). CDC investigators determined that recent antibiotic use and child-care center attendance are risk factors for carriage of and infection with drug-resistant pneumococcus among children. Antibiotic resistance is increasingly common in S. pneumoniae, and infections may be difficult and costly to treat. Children who attend child-care centers are twice as likely as those who do not to develop serious infections with antibiotic-resistant pneumococci, according to the CDC.1
The answer, at least for the most serious infections, appears to be the new pneumococcal conjugate vaccine (PCV7) (Prevnar, Wyeth Lederle Vaccine, Philadelphia). It offers protection against the seven serotypes that most commonly cause invasive disease in children in the United States. PCV7 is effective in children under 2 years old, a group for which previously there was no vaccine available.
"This is a conjugate vaccine designed specifically for kids," says Susan Wootton, MD, a CDC epidemic intelligence service (EIS) officer. "If you look at the top causes of bacteremia or meningitis, strep pneumo is a major pathogen. So to have something that works in the under-2 age group is very welcomed."
The CDC Advisory Committee on Immunization Practices (ACIP) previously recommended that health care providers consider giving the vaccine to children ages 2 years to 59 months who attend group child-care centers.2 However, ACIP has backed off the recommendation in light of a shortage of the vaccine, though the committee still says day-care attendance is a risk factor that should be considered in immunization decisions.3 Children with increased risk for invasive pneumococcal disease (e.g., those with sickle cell anemia) should be targeted first for vaccine. The CDC estimates that about 1.5 million vaccine doses are needed per month in the United States. The supply is projected to run about 15% below that level through March of this year, but the shortage should end in April 2002 when 2 million doses will be available. At that point, clinicians treating children in day care may want to consider administering the vaccine.
"Day-care [centers] are known to have kids carrying all sorts of things," Wootton says. "We know [S. pneumo] is out there, so we need to be thinking how we can use this vaccine. We are [emphasizing that clinicians] become aware of the new vaccine for all kids under 2, and those who fall into high-risk groups. The vaccine has the most impact on severe disease like meningitis." Wootton investigated a case in late 2000 in which an 11-month-old child who went to a day-care center in southwest Georgia was hospitalized for refractory otitis media. Eight days before hospitalization, a culture of drainage obtained from the child’s middle ear revealed S. pneumoniae resistant to penicillin, clindamycin, erythromycin, trimethoprim/sulfamethoxazole, and tetracycline. Wootton and colleagues concluded that that person-to-person transmission of the index strain had occurred at the child-care center.
At the center, the children were divided into two groups consisting of those older and younger than 18 months. Each group had a separate room. However, day-care workers went between the two groups, possibly providing a source for cross-transmission, she says. Nasal swabs were obtained from five of the 12 children who had shared a room with the child who was hospitalized. Swabs were obtained from 17 of the 42 children from the other room. One swab was lost during processing. S. pneumoniae was isolated from 19 (90%) of the 21 nasal cultures. Of those 19, a total of 10 (53%) had susceptibility profiles that were identical to the index strain. Four (40%) of the 10 children with index-strain carriage had shared a room at the child-care center with the hospitalized child.
"We didn’t have what we would call an outbreak, because we didn’t have a lot of kids get sick," Wootton says. "[But] we had one kid who got very sick, and that caught our attention."
Those colonized with S. pneumoniae can remain asymptomatic, yet spread the pathogen to those who may be more susceptible to developing invasive disease. That is somewhat unpredictable, however, because the 11-month-old index case was otherwise healthy and did not have known risk factors for invasive disease. Asymptomatic nasal carriage of pneumococcus is intermittent. Studies suggest that pneumococcus can be found among 15% of adults, but up to 65% of children in day care may be colonized.4
Because of the high carriage rate of pneumococcus among children at the day-care center (90%), investigators recommended vaccinating the children under 5 years old. With a narrowing band of antibiotic options, that may remain the best strategy for avoiding serious infections in day care.
1. Multidrug-Resistant Streptococcus pneumoniae in a Child Care Center — Southwest Georgia, December 2000. MMWR 2002; 50:1,156-1,158.
2. Preventing pneumococcal disease among infants and young children: Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 2000; 49(no. RR-9).
3. Revised updated recommendations on the use of pneumococcal conjugate vaccine in a setting of vaccine shortage — Advisory Committee on Immunization Practices. MMWR 2001; 50:1,140-1,142.
4. Craig AS, Erwin PC, Schaffner W, et al. Carriage of multidrug-resistant Streptococcus pneumoniae and impact of chemoprophylaxis during an outbreak of meningitis at a day care center. Clin Infect Dis 1999; 29:1,257-1,264.