Analysis of Bacterial Isolates from a Large Tertiary Children's Hospital in Beijing, China, During the Mycoplasma Outbreak in 2023

This retrospective analysis characterizes the distribution of bacterial pathogens and the drug-resistance profiles of the predominant isolates during the large-scale Mycoplasma pneumoniae (MP) outbreak of 2023. Strains were collected from Beijing Children's Hospital from January through December 2023. In 2023, 23,169 MP isolates were retrieved from 83,793 specimens. For other bacteria, a total of 5680 strains were isolated from 4759 specimens, with gram-negative bacteria constituting the majority (57.2%). During the MP epidemic in the second half of the year, the numbers of MP-positive cases, Haemophilus influenzae –positive cases and coinfection cases with both pathogens all showed similar upward trends. In 2023, the detection rate of methicillin-resistant Staphylococcus aureus was 24.6%. No penicillin-resistant Streptococcus pneumoniae was detected. Vancomycin resistance was detected in 3 strains (1.9%) of Enterococcus faecium . The rates of extended-spectrum β-lactamases production in Klebsiella pneumoniae and Escherichia coli were 64.0% (210/317) and 65.7% (230/350), respectively. Carbapenem resistance rates were 14.2% (45/317) for K. pneumoniae , 2.6% (9/350) for E. coli and 28.6% (28/98) for Enterobacter cloacae . For Pseudomonas aeruginosa and Acinetobacter baumannii , the carbapenem resistance rates were 12.6% (61/483) and 52.7% (127/241), respectively. Our findings delineate the bacterial distribution and resistance pattern among children at our hospital in 2023. The composition of isolated bacteria shifted during the MP outbreak, underscoring the importance of enhanced bacteriological surveillance during epidemics of predominant respiratory pathogens.