Abstract

G greater than 50% of deaths in children less than 5 years of age are caused by infections, mostly in the neonatal period. This constitutes a substantial public health problem, which is increasingly complicated by the upsurge of antimicrobial-resistant bacteria. Given that nasopharyngeal carriage is crucial in establishing infection for many pathogens, we set out to characterize the antimicrobial resistance patterns of the first colonizers of the neonatal nasopharyngeal mucosa. We recruited 120 pregnant women at rural antenatal clinics in the western region of The Gambia in West Africa and collected nasopharyngeal swabs from both mother and neonate within 10 minutes of birth. Staphylococcus aureus, Streptococcus pneumoniae and Pseudomonas spp. were cultured using standard microbiologic methods, and disc diffusion antibiograms were performed on all isolates following CLSI guidelines. Of 120 neonates, 30 (25%) were colonized with Pseudomonas spp., all of which typed as P. fluorescens, except for one P. stutzeri (API 20 NE BioMérieux, BIOMERIEUX, Basingstoke, United Kingdom). A total of 14 neonates (11.7%) carried S. aureus and 5 of these neonates cocarried P. fluorescens. One neonate also cocarried P. fluorescens and S. pneumoniae (serotype 10A). Five S. aureus isolates were resistant to one or more of erythromycin, trimethoprim-sulfamethoxazole, tetracycline and chloramphenicol (Table. 1). One isolate was resistant to cefoxitin, with an minimum inhibitory concentration of 32 μg/mL (E-test Biomerieux, United Kingdom); confirming it as a methicillin-resistant S. aureus (MRSA). MRSA is an important cause of neonatal infections globally. An isolate from one neonate typed as Elizabethkingia meningoseptica, which was resistant to ceftazidime, colistin and meropenem. E. meningoseptica is an emerging pathogen associated with outbreaks of lethal neonatal infections, which are further complicated by its multidrug resistant phenotype. Cases of E. meningoseptica infection are rarely reported in Africa; to our knowledge, this is the first report of carriage of E. meningoseptica at birth in The Gambia. Colonization with such high rates of P. fluorescens at this early stage is more curious, as little is known is about the role of this pathogen in neonatal infections. While typically noninvasive in humans, P. fluorescens can cause infection in immunocompromised individuals. However, there is currently little information on the role P. fluorescens within the healthy human microbiome. Of 42 mothers whose babies carried at least one pathogen, 11 (36.7%) were colonized with Pseudomonas spp., 12 (28.6%) with S. aureus and 1 with Stenotrophomonas maltophilia; another emerging, multidrug resistant opportunistic pathogen. This study shows that nasopharyngeal colonization with antibiotic-resistant bacteria, including MRSA, occurs rapidly after birth. This is of significant public health concern as it highlights the vulnerability of very young neonates to potentially drug-resistant, outbreak bacterial strains. Despite the small sample size, our findings support the need for interventions, such as improved surveillance, and implementation of outbreak prevention measures in rural delivery and neonatal healthcare facilities.