OBJECTIVE To understand the disinfectant-resistant genes in the gram-negative bacteria isolated from the dirt retention on air recure filters of air conditioners and observe the drug resistance.

METHODS The dirt retention samples were collected from the air return filters of air conditioners of some wards in 3 hospitals of Wuhan (Tongji Hospital of Tongji Medical College of Huazhong University of Science and Technology, Wuhan Central Hospital, and Hubei Provincial Maternal and Child Health Hospital) from 2018 to 2024. The gram-negative bacteria were screened out, the disinfectant-resistant genes in the strains were detected by polymerase chain reaction (PCR), and the results of drug susceptibility test were analyzed.

RESULTS Of 354 dirt retention samples that were collected from the air return filers of air conditioners, 77 were detected with 138 strains of gram-negative bacteria, 87 of which were Acinetobacter baumannii, 50 were Enterobacteriaceae, and 1 was Pseudomonas aeruginosa. The detection rates of qacEΔ1, qacEΔ1-sul1, aceI and qacA/B were 73.19%, 82.61%, 69.57% and 2.90%, respectively. None of the strains were detected with qacC, qacH or qacJ. The result of drug susceptibility test showed that 76.81% of the gram-negative bacteria were resistant to at least 1 type of antibiotic; 93 strains of multidrug-resistant gram-negative bacteria were isolated, most of which were isolated from intensive care unit (ICU). The detection rates of qacEΔ1 and qacEΔ1-sul1 were higher in the drug-resistant strains than those in the non-drug-resistant strains; there were significant differences in the drug resistance rates to carbapenems, quinolones and β-lactams between the qacEΔ1-sul1-positive strains and the qacEΔ1-sul1-negative strains(P < 0.05).

CONCLUSIONS There are drug-resistant gram-negative bacteria contaminations in some wards of the 3 hospitals in Wuhan. The carrying rates of disinfectant-resistant genes of the strains are high, and the strains show varying degree of resistance to the commonly used antibiotics; the strains carrying the qacEΔ1-sul1 have certain statistical association with the drug resistance. It is suggested that the hospital should take targeted disinfection measures for the environment and reasonably use antibiotics.