Nasopharyngeal flora and carriage rates of Haemophilus influenzae type b of healthy infants

Abstract

The present study investigates the nasopharyngeal flora and defines the carriage rates of Haemophilus influenzae type b of 144 healthy infants who visited the well-baby clinic. 224 nasopharyngeal swabs were obtained (44 swabs from 1-month-old infants, 96 swabs from 4 to 5-month-old infants and 84 swabs from 7 to 8-month-old infants), and 440 organisms were isolated. The most frequently isolated organism was Staphylococcus aureus (45.5%) followed by Corynebacterium (38.6%) from 1-month-old infants, Corynebacterium (55.2%) followed by S. aureus (32.3%) and Streptococcus pneumoniae (25.0%) from 4 to 5-month-old infants, Corynebacterium (59.5%) followed by S. pneumoniae (26.2%) from 7 to 8-month-old infants. Twenty-four strains of H. influenzae were isolated from 21 infants, being 1 strain from 1-month-old infant, 9 strains from 4 to 5-month-old infants, 14 strains from 7 to 8-month-old infants. Four type b strains were isolated from 3 infants, being 1 strain from 1-month-old infant, none from 4 to 5-month-old infant, 3 strains from 7 to 8-month-old infants. One of the three 7 to 8-month old infants also carried Hib when he was at the age of 1 month old. The nasopharyngeal carriage rates of H. influenzae of infants were 2.3% in 1-month-old infants, 9.4% in 4 to 5-month-old infants, 16.7% in 7 to 8-month-old infants and 10.7% in total. The carriage rates of Hib were 2.3% in 1-month-old infants, 0% in 4 to 5-month-old infant, 3.6% in 7 to 8-month-old infants and 1.8% in total.