Molecular typing and characterization of isolates from burn wound infections in Fujian, China.

BACKGROUND

() is the most common causative agent of burn wound infection, that often leads to high morbidity and mortality. However, there is not enough knowledge about the molecular epidemiology and antimicrobial susceptibility of isolates from burn wound infections in Fujian, China.

METHODS

Between 2016 and 2021, 90 isolates were collected from burn wound infections in Fujian, China, including 59 methicillin-resistant (MRSA) strains and 31 methicillin-susceptible (MSSA) strains. These were investigated for molecular characteristics, virulence genes, biofilms, and antimicrobial susceptibility. All the isolates were genotyped by multilocus sequence typing (MLST), typing, typing, and SCC typing. Conventional PCR was performed for the detection of virulence genes. Biofilm formation capacity was assessed by tissue culture plate assay (TCP). The antimicrobial susceptibility of the isolates was evaluated using the dilution method.

RESULTS

In total, 37 sequence types (ST) and 34 Staphylococcal protein A () types (including a new type named -t20720) were identified based on multilocus sequence typing (MLST) and typing, respectively. CC8-ST239-t030-I-SCCIII (57.6%,34/59) and CC7-ST7-t091-I (16.1%, 5/31) represented the main clone of MRSA and MSSA isolates, respectively. Antibiotic susceptibility testing identified a significant difference in resistance rates between ST239 and non-ST239 isolates ( < 0.05). Twelve virulence genes were detected, of which the most common were and (both 100%), followed by and (both 96.7%), (95.6%), (81.1%), (62.2%), (50%), (26.7%), and (4.4%). Moreover, , , I, and III were significantly correlated with burn severity ( < 0.05). MRSA isolates were less likely, compared with MSSA isolates, to carry , and ( < 0.05). A new spa type, t20720, was identified that contains , , , , , , , and genes and has strong biofilm formation ability.

CONCLUSION

CC8-ST239-t030-I-SCCIII and CC7-ST-7-t091-I were the prevalent molecular signatures of MRSA and MSSA isolates from burn wound infections in Fujian, China, respectively. The newly identified -t20720 isolate, which carries a wide range of virulence genes and has strong biofilm formation ability, requires special clinical attention.