背景:耐甲氧西林金黄色葡萄球菌(MRSA),被认为是一种潜在的侵袭性医院病原体。它占伊朗三级医院金黄色葡萄球菌分离株的50%,然而,关于这种医学上重要的细菌,没有足够的进化和流行病学调查。我们旨在基于获得的表型和基因型特征,研究2021-2022年伊朗西北部MRSA的谱系和进化。
方法:从大不里士的3家转诊医院收集72种非重复MRSA分离株,Ardebil,和Urmia城市。通过圆盘扩散试验和微量肉汤稀释法确定抗菌敏感性模式。此后4个毒力基因(eta,ETB,pvl,tst)和5种类型的葡萄球菌盒染色体mec(SCCmec)通过PCR检测。在最后一步,选择代表性分离株进行多位点序列分型(MLST)研究.
结果:对红霉素和克林霉素的耐药率最高,为76.4%,其次是环丙沙星(61.1%),庆大霉素(54.2%),利福平(38.9%),和复方新诺明(27.8%)。所有分离株对万古霉素敏感。ETB的毒力基因,pvl,tst,和eta检测到50%,29.2%,21.8%,和13.9%的分离株,分别。SCCmecIII型和I型是最常见的类型,其次是类型IV,II,和V.MLST分析揭示了6种序列类型:ST6854、ST5282、ST127、ST7804、ST1607和ST7784。还鉴定了两种基于MLST的克隆复合物(CC8和CC97)。
结论:ST数值是非重复的。CC8作为大流行克隆和个体谱系和临床上重要的进化枝被报道为最普遍的克隆复合物。必须定期评估抗生素敏感性模式,并研究具有医学挑战性的微生物,特别是MRSA的进化特征,以有效治疗和限制暴发。
BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA), is considered a potential and aggressive nosocomial pathogen. It accounts for 50% of S. aureus isolates in tertiary hospitals in Iran, however, there is no sufficient evolutionary and epidemiological investigation about this medically important bacterium. We aimed to study the lineage and evolution of MRSA in Northwest Iran during 2021-2022 based on the obtained phenotypic and genotypic characteristics.
METHODS: Seventy-two non-duplicate MRSA isolates were collected from 3 referral hospitals in Tabriz, Ardebil, and Urmia cities. The antimicrobial susceptibility patterns were determined by disk diffusion test and micro broth dilution methods. Thereafter 4 virulence genes (eta, etb, pvl, tst) and 5 types of staphylococcal cassette chromosome mec (SCCmec) were detected by PCR. In the final step, representative isolates were selected to be studied by Multilocus sequence typing (MLST).
RESULTS: The highest resistance was observed to erythromycin and clindamycin at a rate of 76.4%, followed by ciprofloxacin (61.1%), gentamicin (54.2%), rifampin (38.9%), and co-trimoxazole (27.8%). All isolates were susceptible to vancomycin. The virulence genes of etb, pvl, tst, and eta were detected in 50%, 29.2%, 21.8%, and 13.9% of isolates, respectively. SCCmec types III and I were the most prevalent types, followed by types IV, II, and V. MLST analysis revealed 6 sequence types: ST6854, ST5282, ST127, ST7804, ST1607, and ST7784. Two MLST-based clonal complexes (CC8, and CC97) were identified as well.
CONCLUSIONS: The ST numbers were non-repetitive. CC8 as a pandemic clone and an individual lineage and clinically significant clade was reported as the most prevalent clonal complex. It is essential periodic evaluations of antibiotic susceptibility patterns and study the evolutionary characteristics of medical-challenging microorganisms in particular MRSA to effectively treat and restrict the outbreaks.