No abstract

Six strains of ampicilhin-resistant Haemophilus influenzae type b were studied in vitro for synergy between ampicillin and nafcillin. The miniimal inhibitory concentrations for these strains with 10' colony-forming units per ml were 6.25 to 12.5 ug of ampicillin per ml and 6.25 to 25 ,ug

Differences in mean birth weight and low birth weight ((2.5 Kg.) are analyzed among Asians, Blacks, Hispanics, and Whites who were enrolled in the Northern California Kaiser-Permanente Birth Defects Study, a prospective study of 29,415 pregnancy outcomes. Large differences in birth weight among babies of different ethnic groups persist after controlling for the joint effects of maternal smoking and alcohol use during pregnancy, sex of child, parity, length of prenatal care, and maternal weight-forheight percentile. Compared to Whites, the relative mean differences in birth weight are estimated as-246 grams for Blacks,-210 grams for Asians,-105 grams for Hispanics, and-140 grams for Others. The low birth weight rates and crude odds ratios are 7.70% (2.17) for Blacks, 5.57% (1.57) for Asians 5.52% (1.55) for Others, 4.00% (1.13) for Hispanics, and 3.55% (1.00) for Whites. After controlling for the effects of 21 factors, the odds ratios for a low birth weight infant are 2.41 for Blacks, 1.37 for Asians, 1.93 for Others, and 1.25 for Hispanics. It is concluded that factors currently used to control for ethnic differences in birth weight are insufficient to explain the observed differences.