Abstract 1220 Poster Session II, Sunday, 5/2 (poster 8)

Recent reports of the frequent resistance of Group B streptococci(GBS) to erythromycin and clindamycin have raised concerns about the use of these antibiotics as alternative prophylactic agents for the prevention of early-onset disease(EOD)in neonates. We determined the antibiotic susceptibility profiles of 106 strains of GBS from infants with EOD in 14 hospitals within 6 U.S. academic centers between 7/19/95 and 12/31/97. Each strain was tested against ten antibiotics using MICroSTREP Panels(Dade International Inc.) and two antibiotics (levofloxacin & trovafloxacin) using E-test (AB BIODISK). Susceptibility was graded according to 1998 guidelines of the National Committee for Clinical Laboratory Standards. All strains were sensitive to penicillin, ampicillin, cefotaxime, ceftriaxone, chloramphenicol, levofloxacin, trimethoprim, sulfamethoxazole, trovafloxacin and vancomycin. Among all isolates, 20% were resistant to erythromycin(E), 9% to clindamycin(Cd), and 96% to tetracycline. The frequency of resistance varied with geographical location (Table).

Table 1 No caption
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The resistance to erythromycin increased from 13% in 1995 and 1996 to 30% in 1997; resistance to clindamycin was 14% in 1995, 0% in 1996 and 14% in 1997. The resistance by serotype was as follows: to erythromycin: 6/42(14%)Ia, 1/13(8%)Ib, 0/6(0%)II, 5/23(22%)III, and 9/19(44%)V and 0/3 of non-typable (NT); resistance to clindamycin: 0/42(0%)Ia, 1/13(8%)Ib, 0/6(0%)II, 2/23(9%)III, 7/19(37%)V and 0/3(0%) NT. Type V strains are significantly more resistant to both erythromycin and clindamycin than other serotypes (p= .002, and .0002, respectively, Fisher exact test). In summary, our data show a continued universal sensitivity of GBS to penicillin and ampicillin. However, erythromycin resistance which varies among regions has recently emerged. Resistance to both erythromycin and clindamycin is most frequently observed in serotype V strains. These results suggest that, for women who are penicillin intolerant, the selection of alternative prophylactic antibiotic regimens should be guided by the contemporary antibiotic resistance patterns in the region. In the absence of such data, erythromycin and clindamycin cannot be relied upon as alternative antibiotics for GBS prophylaxis.