Shafipour Maryam, Emrani Niloufar, Shahryari Ali
Department of Environmental Health Engineering, School of Health, Golestan University of Medical Science, Gorgan, Iran.
Department of Pediatric Dentistry, School of Dentistry, Golestan University of Medical Sciences, Gorgan, Iran.
BMC Oral Health. 2025 Aug 11;25(1):1313. doi: 10.1186/s12903-025-06668-x.
Pseudomonas aeruginosa is a leading cause of healthcare-associated infections (HAIs), especially in dental environments. In this study, we examine the prevalence of virulence factors in P. aeruginosa isolated from dental chair unit (DCU) water, aiming to evaluate the hygienic status of dental unit waterlines (DUWLs).
A total of 100 water samples were collected from DCU and the urban water supply at the Dental Faculty of Gorgan, Iran. The samples were cultured in Mueller-Hinton Broth, and DNA was extracted. Molecular identification was performed using gyrB-specific primers, with five isolates confirmed by Sanger sequencing and BLAST analysis. P. aeruginosa was detected in 95 samples. The prevalence of virulence genes (exoS,algD, toxA, and lasB) was assessed via multiplex PCR.
Among 95 isolates, 72.63% (69/95) harbored all four genes, with lasB and algD each present in 97.1%, toxA in 95.65%, and exoS in 78.26%. Gene frequencies varied across sites: urban water inlet (12.5%), dental handpiece (83.87%), air-water syringe (75.67%), and water nozzle (81.25%). All five clinical isolates harbored silent mutations in gyrB (C→T132, T→C144, and A→T 111) that preserved the wild-type gyrB amino acid sequence. As all mutations were silent (C→T132, T→C144, A→T111), no structural alterations were observed in the gyrB protein.
These findings highlight that DUWLs act as reservoirs for P. aeruginosa strains harboring multiple virulence genes associated with biofilm formation. Targeted strategies are urgently needed to disrupt both bacterial growth and gene expression, which could help reduce antibiotic resistance and improve infection control in dental care.
铜绿假单胞菌是医疗保健相关感染（HAIs）的主要病因，尤其是在牙科环境中。在本研究中，我们检测了从牙科治疗椅单元（DCU）水中分离出的铜绿假单胞菌毒力因子的流行情况，旨在评估牙科单元水线（DUWLs）的卫生状况。
从伊朗戈尔甘牙科学院的DCU和城市供水系统中总共采集了100份水样。将样本在穆勒-欣顿肉汤中培养，然后提取DNA。使用gyrB特异性引物进行分子鉴定，通过桑格测序和BLAST分析确认了5株分离株。在95个样本中检测到了铜绿假单胞菌。通过多重PCR评估毒力基因（exoS、algD、toxA和lasB）的流行情况。
在95株分离株中，72.63%（69/95）携带所有四个基因，lasB和algD各占97.1%，toxA占95.65%，exoS占78.26%。基因频率在不同部位有所不同：城市进水口（12.5%）、牙科手机（83.87%）、气水注射器（75.67%）和水喷嘴（81.25%）。所有五株临床分离株的gyrB均存在沉默突变（C→T132、T→C144和A→T 111），这些突变保留了野生型gyrB氨基酸序列。由于所有突变均为沉默突变（C→T132、T→C144、A→T111），因此在gyrB蛋白中未观察到结构改变。
这些发现突出表明，DUWLs是携带与生物膜形成相关的多种毒力基因的铜绿假单胞菌菌株的储存库。迫切需要有针对性的策略来破坏细菌生长和基因表达，这有助于降低抗生素耐药性并改善牙科护理中的感染控制。
