Research on etiological sampling for large-scale object surfaces in hospitals based on enrichment technology

OBJECTIVE To compare the effect of traditional swab sampling method on etiological surveillance of infectious diseases for large-scale object surfaces in hospitals and validate the samples processing method based on pre-wet anti-static fabric and modified polyethylene glycol (PEG) precipitation enrichment technology so as to improve the capability of early warning of infectious diseases and optimize the environmental surveillance program in the hospitals.

METHODS The on-site surveillance was carried out for 8 times in 3 public hospitals (Shenzhen Longgang People′s Hospital, the Second People′s Hospital of Longgang and Longgang Maternal and Child Health Hospital) from May 2024 to Mar. 2025. Totally 23 types of respiratory tract pathogens (18 types of viruses, 5 type of pathogenic bacteria) and 6 types of gastrointestinal tract pathogens were simultaneously detected by means of fluorescent quantitative polymerase chain reaction (PCR); the actual isolation rates, etiological spectrum and cycle threshold (Ct) value were compared. The acrylic plate added with standards of different loads of H1NI influenza viruses was used as model for laboratory evaluation. The minimum detection limit, sensitivity and repeatability were observed and compared between the methods.

RESULTS The minimum detection limit of both methods was 6.0×10⁴ copies/ml, however, the positive rate of nucleic acid testing of the pre-wet fabric method was 100.00% (3/3), higher than 33.33% (1/3) of the swab method; when the low viral load was 6.0×10⁵ copies/ml, the average concentration of viral nucleic acid of the pre-wet fabric method (X-_Ct=36.59) was higher, with the repeatability (CV=0.99%, < 3.14%) better. The results of the on-site surveillances showed that the total isolation rates of pathogens of the pre-wet fabric method ranged between 42.84% and 64.27%, higher than between 10.71% and 21.43% of the swab method, with the isolated pathogens more abundant, the Ct value lower(P < 0.05).

CONCLUSION The pre-wet fabric sampling enrichment method integrated with anti-static fabric sampling and PEG enrichment technology shows higher sensitivity and stability in the etiological surveillance of large-scale object surfaces, raising the isolation rate.