Nour El-Din Hanzada T, Yassin Aymen S, Ragab Yasser M, Hashem Abdelgawad M
Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, 11562, Egypt.
Department of Microbiology and Immunology, Faculty of Pharmacy, British University in Egypt, El-Sherouk City, Cairo, 11837, Egypt.
Infect Drug Resist. 2021 Apr 21;14:1557-1571. doi: 10.2147/IDR.S296000. eCollection 2021.
Methicillin-resistant (MRSA) presents a profound hazard to public health. MRSA colonizing skin, mucous membranes, and the anterior nares without clinical symptoms is termed "colonizing MRSA". Upon manifestation of clinical symptoms, it is termed "infectious MRSA". Here, we characterize and differentiate colonizing and infectious MRSA, and analyze the phenotypic-genotypic and antibiotic susceptibility correlations.
Clinical MRSA isolates were recovered from intensive care units (ICUs) of two major Egyptian hospitals and their biofilm formation ability was tested. Antibiograms against 16 antibiotics were determined, in addition to the minimum inhibitory concentrations (MICs) of vancomycin and linezolid. The entire collection was typed by enterobacterial repetitive intergenic consensus (ERIC)-PCR, as well as multi-locus sequence typing (MLST). Representative resistance and virulence genes were detected by PCR amplification.
Forty-nine isolates were confirmed as MRSA, of which 30 isolates were infectious and 19 were colonizing. Versatile resistance patterns were observed in both groups of isolates. We report a higher tendency for biofilm-formation and borderline minimum inhibitory concentrations among infectious isolates. A Positive antibiotic correlation was observed between susceptibility to protein synthesis inhibitors and cell wall inhibitors. Positive correlations were observed between isolation site and rifampicin resistance: nasal samples were enriched in rifampicin-resistant isolates, while urine and blood samples were enriched in susceptible ones. Furthermore, biofilm formation ability was slightly associated with amikacin resistance, and an association between teicoplanin resistance and the presence of the Panton-Valentine leukocidin gene was the only significant phenotype-genotype correlation observed. Finally, ERIC typing and MLST had congruent results.
Linezolid and vancomycin are still the most convenient choice for MRSA treatment. ERIC PCR and MLST show promising typing combination that could be easily used periodically for tracking the genotypic changes of MRSA, especially within the healthcare facilities. Several correlations were established between groups of antibiotics and the genotypes/phenotypes of the selected isolates.
耐甲氧西林金黄色葡萄球菌（MRSA）对公众健康构成严重威胁。定植于皮肤、黏膜和前鼻孔且无临床症状的MRSA被称为“定植型MRSA”。出现临床症状时，则被称为“感染型MRSA”。在此，我们对定植型和感染型MRSA进行特征描述和区分，并分析表型-基因型及抗生素敏感性之间的相关性。
从埃及两家主要医院的重症监护病房（ICU）分离出临床MRSA菌株，并检测其生物膜形成能力。除了测定万古霉素和利奈唑胺的最低抑菌浓度（MIC）外，还确定了针对16种抗生素的抗菌谱。通过肠杆菌重复基因间共识（ERIC）-PCR以及多位点序列分型（MLST）对整个菌株集合进行分型。通过PCR扩增检测代表性的耐药和毒力基因。
49株菌株被确认为MRSA，其中30株为感染型，19株为定植型。两组菌株均观察到多种耐药模式。我们报告感染型菌株中生物膜形成趋势更高且最低抑菌浓度处于临界值。在对蛋白质合成抑制剂和细胞壁抑制剂的敏感性之间观察到正性抗生素相关性。在分离部位与利福平耐药性之间观察到正相关：鼻拭子样本中利福平耐药菌株富集，而尿液和血液样本中敏感菌株富集。此外，生物膜形成能力与阿米卡星耐药性略有相关，而替考拉宁耐药性与杀白细胞素基因的存在之间的关联是观察到的唯一显著的表型-基因型相关性。最后,ERIC分型和MLST结果一致。
利奈唑胺和万古霉素仍然是治疗MRSA最方便的选择。ERIC-PCR和MLST显示出有前景的分型组合，可轻松定期用于追踪MRSA的基因型变化，尤其是在医疗机构内。在所选菌株的抗生素组与基因型/表型之间建立了多种相关性。
