Laboratory Medicine ›› 2025, Vol. 40 ›› Issue (5): 450-454.DOI: 10.3969/j.issn.1673-8640.2025.05.006

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Virulence characteristics of Streptococcus pneumoniae,PBP gene mutation and β-lactam resistance

YAO Ling1, GAO Chunyan2(), LIU Minglei2   

  1. 1. Department of Prenatal Diagnosis,Tangshan Maternal and Child Health Hospital,Tangshan 063000,Hebei,China
    2. Department of Clinical Laboratory,Tangshan Material and Child Health Hospital,Tangshan 063000,Hebei
  • Received:2023-05-18 Revised:2024-04-03 Online:2025-05-30 Published:2025-06-04

Abstract:

Objective To analyze the virulence characteristics of Streptococcus pneumoniae,penicillin-binding protein (PBP) gene mutation and β-lactam resistance. Methods Totally,25 clinical isolates of Streptococcus pneumoniae were collected from Tangshan Maternal and Child Health Hospital from January to December 2022. The isolates were identified by automatic microbial identification drug susceptibility instrument. The minimum inhibitory concentrations (MIC) of penicillin,amoxicillin,cefuroxime and ceftriaxone sodium were determined by microbroth dilution method. The virulence genes (PlyLytANanAPsaA and PspA)of Streptococcus pneumoniae were determined by polymerase chain reaction (PCR). The correlation between PBP2b gene mutation and β-lactam resistance was analyzed. Results Among the 25 isolates of Streptococcus pneumoniae,21 (84.00%) isolates were isolated from sputum samples. Totally,10(40.00%)isolates were sensitive to β-lactam antibiotics. There were 15(60.00%)isolates resistant to β-lactam antibiotics,and the MIC of 3 isolates were 4-32 μg·mL-1. The PBP2b positive rate of 25 isolates of Streptococcus pneumoniae was 100.00%. There were 5 resistant isolates with low MIC(1-2 μg·mL-1),and serine-X-Y lysine was changed. There were 7 isolates with medium MIC(1-4 μg·mL-1),and serine-X-Y lysine,serine-X-Y asparagine and lysine-threonine/serine-glycine were changed. There were 3 isolates with high MIC(4-32 μg·mL-1),and there were changes of threonine 445/451-alanine/serine and lysune-threonine/serine-glycine in the conserved region of PBP2b coding sequence near SSN. The positive rates of nanALytA and Ply were 80.00%,and the positive rate of nanA+Ply+LytA model was the highest(56.00%). Conclusions Threonine 445/451-alanine/serine and lysune-threonine/serine-glycine are related to β-lactam resistance in the conserved region of PBP2b coding sequence,and the virulence genes(nanALytA and Ply)are widely distributed.

Key words: Streptococcus pneumoniae, Penicillin-binding protein, Gene mutation, β-lactam antibiotic, Virulence gene, Drug resistance

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