背景。铜绿假单胞菌是一种侵袭性生物,经常在糖尿病足溃疡中引起严重的组织损伤。差距声明。在突尼斯尚未进行从糖尿病足感染中分离的铜绿假单胞菌菌株的表征。目的。目的是确定从突尼斯糖尿病足感染(DFIs)患者中分离出的铜绿假单胞菌的患病率,并表征其耐药性。毒力和分子分型。方法。突尼斯国际医院中心糖尿病科收治的DFI患者,从2019年9月至2021年4月,纳入本前瞻性研究.铜绿假单胞菌从伤口拭子中获得,在常规临床护理期间进行抽吸和软组织活检,并通过基质辅助激光解吸/电离飞行时间质谱进行确认。抗菌药物敏感性试验,血清分型,整合子和OprD表征,毒力,生物膜生产,色素定量,弹性蛋白酶活性和分子分型分析在所有回收的铜绿假单胞菌分离株通过表型试验,特定的PCRs,测序,测序脉冲场凝胶电泳(PFGE)和多位点序列分型。结果。从78例糖尿病患者的98个样本中回收了16个铜绿假单胞菌(16.3%),并分为6种血清型(O:11最常见),11种不同的PFGE模式和10种序列类型(其中三种是新的)。在两个分离物中发现了高风险克隆ST235。对奈替米星(69%)和头孢吡肟(43.8%)的抗性最高。检测到4株多重耐药(MDR)分离株(25%),其中三个是耐碳青霉烯的。ST235-MDR菌株含有In511类整合子(intI1+aadA6+orfD+qacED1-sul1)。根据对14个参与毒力或群体感应的基因的检测,观察到5个病毒型,包括5个exoU阳性,9个exoS阳性菌株和2个exoU/exoS阳性菌株。在一个分离物中,lasR基因被ISPpu21插入序列截短,在ST235-MDR菌株中检测到rhlR基因缺失64bp。低生物膜,在所有铜绿假单胞菌中都检测到了铜绿假单胞菌和弹性蛋白酶的产生;然而,lasR截短的菌株表现出慢性感染表型,其特征是血清型特异性抗原性丧失,吩嗪的高产量和高生物膜形成。Conclusions.我们的研究首次证明了来自突尼斯DFIs的铜绿假单胞菌菌株的患病率和分子特征,表现出高度的遗传多样性,中度抗菌素耐药性,但是大量的毒力相关性状,强调其病理重要性。
Background. Pseudomonas aeruginosa is an invasive organism that frequently causes severe tissue damage in diabetic foot ulcers.Gap statement. The characterisation of P. aeruginosa strains isolated from diabetic foot infections has not been carried out in Tunisia.Purpose. The aim was to determine the prevalence of P. aeruginosa isolated from patients with diabetic foot infections (DFIs) in Tunisia and to characterize their resistance, virulence and molecular typing.Methods. Patients with DFIs admitted to the diabetes department of the International Hospital Centre of Tunisia, from September 2019 to April 2021, were included in this prospective study. P. aeruginosa were obtained from the wound swabs, aspiration and soft tissue biopsies during routine clinical care and were confirmed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Antimicrobial susceptibility testing, serotyping, integron and OprD characterization, virulence, biofilm production, pigment quantification, elastase activity and molecular typing were analysed in all recovered P. aeruginosa isolates by phenotypic tests, specific PCRs, sequencing, pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing.Results. Sixteen P. aeruginosa isolates (16.3 %) were recovered from 98 samples of 78 diabetic patients and were classified into 6 serotypes (O:11 the most frequent), 11 different PFGE patterns and 10 sequence types (three of them new ones). The high-risk clone ST235 was found in two isolates. The highest resistance percentages were observed to netilmicin (69 %) and cefepime (43.8 %). Four multidrug-resistant (MDR) isolates (25 %) were detected, three of them being carbapenem-resistant. The ST235-MDR strain harboured the In51 class 1 integron (intI1 +aadA6+orfD+qacED1-sul1). According to the detection of 14 genes involved in virulence or quorum sensing, 5 virulotypes were observed, including 5 exoU-positive, 9 exoS-positive and 2 exoU/exoS-positive strains. The lasR gene was truncated by ISPpu21 insertion sequence in one isolate, and a deletion of 64 bp in the rhlR gene was detected in the ST235-MDR strain. Low biofilm, pyoverdine and elastase production were detected in all P. aeruginosa; however, the lasR-truncated strain showed a chronic infection phenotype characterized by loss of serotype-specific antigenicity, high production of phenazines and high biofilm formation.Conclusions. Our study demonstrated for the first time the prevalence and the molecular characterization of P. aeruginosa strains from DFIs in Tunisia, showing a high genetic diversity, moderate antimicrobial resistance, but a high number of virulence-related traits, highlighting their pathological importance.