Antimicrobial resistance patterns of colonizing Streptococcus pneumoniae among young child-mother pairs in the rural highlands of the Peruvian Andes

BACKGROUND: Despite widespread use of pneumococcal conjugate vaccines (PCVs), Streptococcus pneumoniae (pneumococcus) remains an important cause of pneumonia. Prior to widespread PCV use, we found a high prevalence of nasopharyngeal (NP) colonization with pneumococcus resistant to multiple antibiotic classes among young children in the rural highlands of Peru. We sought to confirm contemporary resistance profiles among young children, their mothers, and animal contacts in the post-PCV era. METHODS: We enrolled eligible members of Peruvian households whose children had participated in our previous study. Mothers were questioned about antibiotic use for themselves and their children age <3 years. NP samples were collected from children, mothers, and their animal contacts including cows, guinea pigs, and dogs, when available. Samples were cultured for pneumococcus using standard methods and routine disk antibiotic susceptibility testing was performed. Drinking water and milk samples were tested, when available, for the presence of β-lactam and tetracycline residues (IDEXX Β-Tetra testing kit; Westbrook, ME). RESULTS: Members of 47 households were enrolled, including 50 children and 47 mothers (3 sibling pairs). The median (IQR) age of children was 1.2 years (0.6-2.2) and number of household members was 5 (4-6). Sixteen of 50 (32%) children and 7/47 (15%) mothers had received antibiotics in the prior 6 months (Fig 1). Pneumococcus was detected in 31/50 (62%) children, 9/47 (19%) mothers, and 1/31 (3%) guinea pigs. Pneumococci were not detected in dogs (n = 29) or cows (n = 7). Resistance to multiple classes of antibiotics, including TMP-SMX, tetracyclines, and β-lactams, was common among children and adults (Fig 2). No antibiotic residues were detected in water (n = 41) or milk (n = 7) samples. CONCLUSION: Pneumococcal colonization was common among young children, less prevalent among adults, and rare among animals. Resistance to macrolides and tetracyclines was common despite very little reported use of these antibiotics in people. Additional studies should evaluate whether this high prevalence of resistance is a result of local prescribing practices or unintentional environmental exposures. ADDIN EN.REFLIST DISCLOSURES: K. Edwards, Novartis: Grant Investigator, Research grant. M. Griffin, MedImmune: Grant Investigator, Grant recipient. C. Lanata, Takeda: Scientific Advisor, Consulting fee. C. G. Grijalva, Pfizer: Consultant, Consulting fee.