Infectious Diseases and Tropical Medicine Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
Department of Microbiology, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
J Chin Med Assoc. 2018 Feb;81(2):127-132. doi: 10.1016/j.jcma.2017.08.016. Epub 2017 Oct 9.
Pseudomonas aeruginosa is an opportunistic pathogen involved in many infections. Carbapenem-resistant P.aeruginosa has emerged as an important cause of infection in different hospitals worldwide. We aimed to determine frequencies of the four main resistance mechanisms [metallo-beta lactamase (MBL) production (bla, bla, bla and bla), overproduction of the MexAB-OprM and MexXY efflux pumps, overproduction of chromosome-encoded AmpC β-lactamase, and reduced OprD expression] in high-level carbapenem-resistant P.aeruginosa isolated from patients with burns.
In a descriptive study, 107 P. aeruginosa isolates were collected from patients with burn injuries and tested for antibiotic susceptibility, by an E-test for carbapenems, an E-test for metallo-β-lactamase producer isolates, and PCR to detect MBL genes. Furthermore, high-level carbapenem-resistant isolates were tested by real-time PCR for the expression levels of the mexB, mexY, ampC, and oprD genes.
Amongst all P. aeruginosa isolates, 78.5%, 46.7%, and 15% were imipenem-, meropenem-, and doripenem-resistant, respectively; 72% of isolates were multidrug-resistant. The bla and bla genes were detected in 17.9% and 1.2% of isolates; respectively. The bla and bla genes were not observed. Among the resistant isolates, mexB overexpression (63.2%) was the most frequent mechanism, followed by mexY overexpression (52.6%), ampC overexpression (36.8%), and reduced oprD expression (21.1%).
Emerging antimicrobial resistance in burn wound bacterial pathogens is a serious therapeutic challenge for clinicians. In the present study, most of the isolates were MDR. This finding indicated an alarming spread of resistant isolates and suggested that infection control strategies should be considered. Resistance to carbapenems is influenced by several factors, not all of which were evaluated in our study; however, the results showed that production of MBLs and overexpression of the mexB gene were the most frequent mechanisms in carbapenem-resistant isolates.
铜绿假单胞菌是一种机会性病原体，可引起多种感染。耐碳青霉烯类铜绿假单胞菌已成为全球不同医院感染的重要原因。我们旨在确定高耐碳青霉烯类铜绿假单胞菌的四种主要耐药机制（金属β-内酰胺酶（MBL）产生（bla、bla、bla 和 bla）、MexAB-OprM 和 MexXY 外排泵过度表达、染色体编码 AmpC β-内酰胺酶过度表达和 OprD 表达减少）在烧伤患者分离的高耐碳青霉烯类铜绿假单胞菌中的频率。
在一项描述性研究中，从烧伤患者中收集了 107 株铜绿假单胞菌分离株，并通过 E 试验检测碳青霉烯类药物的药敏性、金属β-内酰胺酶产生菌的 E 试验和 PCR 检测 MBL 基因。此外，通过实时 PCR 检测高耐碳青霉烯类铜绿假单胞菌 mexB、mexY、ampC 和 oprD 基因的表达水平。
在所有铜绿假单胞菌分离株中，分别有 78.5%、46.7%和 15%对亚胺培南、美罗培南和多利培南耐药；72%的分离株为多药耐药。在 17.9%和 1.2%的分离株中分别检测到 bla 和 bla 基因。未观察到 bla 和 bla 基因。在耐药分离株中，mexB 过度表达（63.2%）是最常见的机制，其次是 mexY 过度表达（52.6%）、ampC 过度表达（36.8%）和 oprD 表达减少（21.1%）。
烧伤创面细菌病原体出现的新出现的抗菌药物耐药性对临床医生是一个严重的治疗挑战。在本研究中，大多数分离株为 MDR。这一发现表明耐药分离株的传播令人震惊，并表明应考虑感染控制策略。碳青霉烯类耐药性受多种因素影响，并非所有因素均在本研究中进行评估；然而，结果表明，MBL 的产生和 mexB 基因的过度表达是碳青霉烯类耐药分离株中最常见的机制。
