Neonatal Nasopharyngeal Bacterial Colonization: Prevalence, Antimicrobial Resistance, and Concomitant Early-onset Sepsis

Abstract

Background: Early-onset neonatal sepsis (ENOS) is one of the most common causes of mortality in neonates. The bacteria causing ENOS are generally transferred from the mother to the infant before or during labor. Objectives: This study aimed to determine the prevalence rate of nasopharyngeal colonization with common bacterial agents causing ENOS and their relationship with blood culture outcomes in neonates. Methods: All neonates transferred to the neonatal intensive care unit were included in the study. Posterior pharynx secretions were swabbed and cultured in blood agar and MacConkey agar. Also, a blood specimen from each neonate was inoculated into a blood culture bottle. The grown bacteria were identified by biochemical standard tests. The antibiotic sensitivity test was performed by the disk diffusion method using Mueller-Hinton agar, and the results were evaluated according to the CLSI guidelines. Results: The pharyngeal specimens collected from 114 newborns were positive in 83 (72.8%) cases. Staphylococcus epidermidis was the most common bacterium in all weight groups. However, the isolates of Klebsiella, Escherichia coli, S. aureus, and Streptococcus agalactiae were also high. Thirteen newborns died. Neonates’ pharyngeal specimens were positive among 11 (84.6%) cases who died and 101 (71.2%) neonates who survived. Twelve neonates had positive blood cultures. Simultaneous positive blood and pharyngeal cultures were reported in eight (7%) cases, in which the bacterial isolates from blood and pharyngeal samples were similar in three cases (37.5%). Among pharyngeal isolates, E. coli was resistant to ampicillin in 100% and gentamicin, cefotaxime, and ceftazidime in 50% of the cases. Also, S. epidermidis and Acinetobacter isolates from blood samples were resistant to ampicillin in 100% of the cases. Conclusions: Staphylococcus epidermidis accounted for 38.6% of bacteria cultured from pharyngeal swabs and 66.7% of bacteria cultured from blood samples, 37.5% of which were resistant to ampicillin and 100% were sensitive to vancomycin. One-hundred percent of E. coli cultures from neonatal pharynges were resistant to ampicillin and about 50% of them were resistant to gentamicin, cefotaxime, and ceftriaxone.