Abstract: Objective To explore the natural infection status of Streptococcus pneumoniae in captive bred rhesus macaques, and to provide reference for the clinical diagnosis and treatment of Streptococcus pneumoniae infection. Methods Twenty infant monkeys, 30 adult monkeys and 30 elderly monkeys were randomly selected from a rhesus macaques population, and the nasal swabs and pharynx swabs were collected and screened for Streptococcus pneumoniae simultaneously by bacterial culture and real-time fluorescent quantitative PCR. The mother monkeys of the positive infant monkeys were screened for Streptococcus pneumoniae. Gram staining method, Optochin drug sensitivity test, bile solubility test, inulin fermentation test and PCR amplification and sequencing were used to further identification. Results The positive rate of rhesus macaques carrying Streptococcus pneumoniae was 20% (4/20), and the mother macaques of the four positive infant macaques tested negative. The positive rate was 0% in both adult and elderly rhesus monkeys. The morphological observation results of the bacterial culture showed that the bacteria appeared gray and raised, and produced a surrounding green zone of hemolysis with a flattened center, indicating typical Streptococcus pneumoniae colony characteristics. The results of Gram dyeing, bile dissolution test, and inulin fermentation test were all positive, and the bacteria were sensitive to Optochin. The above results showed that the four strains isolated from the infant monkeys’ nasopharyngeal swabs were Streptococcus pneumoniae. Conclusion The investigation findings show that Streptococcus pneumoniae is mainly found in the noses and throats of 20% infant monkeys among rhesus macaques, and no vertical transmission from mother to child is found.

Key words: Rhesus macaques, Streptococcus pneumoniae, Carrying rate, Infant monkeys