Abstract：
BACKGROUND: Pediatric sepsis due to Staphylococcus aureus (S. aureus) is associated with high morbidity and mortality. Accessory-Gene-Regulator (agr) has a role in the pathogenesis of S. aureus through controlling and regulating the expression of virulence genes. Therefore, the aim of the present study was to investigate the prevalence of genotypes of the agr system in S. aureus isolated from children with sepsis and to assess their relationship to biofilm formation and antibiotic resistance.
METHODS: The study was a retrograde cross-sectional study that included 131 children with health care associated sepsis due to S. aureus. The isolated S. aureus was investigated for their ability to form biofilm by microplate method, antibiotic susceptibility pattern by disc diffusion method, and molecular determination of agr genotypes by polymerase chain reaction (PCR).
RESULTS: Methicillin resistant S. aureus (MRSA) was defined by resistance to cefoxitin antibiotic disc in 70 (53.4%) of the isolates and biofilm formation was positive in 67 (58%) of the isolates. Molecular study of the agr genes revealed that 54 (41.2%), 40 (30.5%), 27 (20.6%), and 10 (7.5%) of the studied isolates had agr I, agr II, agr III, and agr IV, respectively. In comparison between MRSA and methicillin sensitive S. aureus (MSSA), there was a signif-icant increase in biofilm formation among MRSA (65.7%, p = 0.01) compared to MSSA (34.3%) and an increase in agr genotype I among MRSA (68.6%, p = 0.001) compared to agr I in MSSA (9.8%). There was a significant association with the presence of a central venous catheter (51.4%, p = 0.001) and urinary tract catheter (81.4%, p = 0.001) in children with MRSA compared to children with MSSA (21.3%, OR = 3.9, 95% CI = 1.8 - 8.5 and 36.1%, OR = 7.8, 95% CI 3.5 - 17.3, respectively).
CONCLUSIONS: There was an increase in the biofilm formation among S. aureus isolated from pediatric patients with sepsis with a significant increase in MRSA. The agr group I was the main agr gene among the isolated S. aureus. Moreover, agr I was the predominant gene in MRSA isolates and was significantly associated with biofilm formation.
METHODS: The study was a retrograde cross-sectional study that included 131 children with health care associated sepsis due to S. aureus. The isolated S. aureus was investigated for their ability to form biofilm by microplate method, antibiotic susceptibility pattern by disc diffusion method, and molecular determination of agr genotypes by polymerase chain reaction (PCR).
RESULTS: Methicillin resistant S. aureus (MRSA) was defined by resistance to cefoxitin antibiotic disc in 70 (53.4%) of the isolates and biofilm formation was positive in 67 (58%) of the isolates. Molecular study of the agr genes revealed that 54 (41.2%), 40 (30.5%), 27 (20.6%), and 10 (7.5%) of the studied isolates had agr I, agr II, agr III, and agr IV, respectively. In comparison between MRSA and methicillin sensitive S. aureus (MSSA), there was a signif-icant increase in biofilm formation among MRSA (65.7%, p = 0.01) compared to MSSA (34.3%) and an increase in agr genotype I among MRSA (68.6%, p = 0.001) compared to agr I in MSSA (9.8%). There was a significant association with the presence of a central venous catheter (51.4%, p = 0.001) and urinary tract catheter (81.4%, p = 0.001) in children with MRSA compared to children with MSSA (21.3%, OR = 3.9, 95% CI = 1.8 - 8.5 and 36.1%, OR = 7.8, 95% CI 3.5 - 17.3, respectively).
CONCLUSIONS: There was an increase in the biofilm formation among S. aureus isolated from pediatric patients with sepsis with a significant increase in MRSA. The agr group I was the main agr gene among the isolated S. aureus. Moreover, agr I was the predominant gene in MRSA isolates and was significantly associated with biofilm formation.
摘要：
背景：金黄色葡萄球菌引起的小儿败血症（S.金黄色葡萄球菌)与高发病率和死亡率相关。副基因调节因子(agr)通过控制和调节毒力基因的表达在金黄色葡萄球菌的发病机制中起作用。因此,本研究的目的是调查从脓毒症患儿分离的金黄色葡萄球菌中agr系统基因型的患病率,并评估其与生物膜形成和抗生素耐药性的关系.
方法：本研究是一项回顾性横断面研究，纳入了131名患有金黄色葡萄球菌引起的卫生保健相关败血症的儿童。通过微孔板法研究了分离的金黄色葡萄球菌形成生物膜的能力，通过圆盘扩散法的抗生素敏感性模式，并通过聚合酶链反应（PCR）对agr基因型进行分子测定。
结果：耐甲氧西林金黄色葡萄球菌（MRSA）的定义是70（53.4％）的分离株对头孢西丁抗生素盘的耐药性，而67（58％）的分离株的生物膜形成为阳性。对agr基因的分子研究表明，54(41.2%)，40（30.5%），27（20.6%），和10（7.5％）的研究分离株具有agrI，agrII,agrIII,和AGRIV，分别。在MRSA和甲氧西林敏感金黄色葡萄球菌（MSSA）之间的比较，MRSA的生物膜形成明显增加(65.7%，p=0.01）与MSSA（34.3％）相比，MRSA中agr基因型I的增加（68.6％，p=0.001)与MSSA中的agrI(9.8%)相比。与中心静脉导管的存在存在显着关联（51.4％，p=0.001）和尿路导尿管（81.4％，与MSSA儿童相比，MRSA儿童的p=0.001（21.3％，OR=3.9，95%CI=1.8-8.5和36.1%，OR=7.8，95%CI分别为3.5-17.3)。
结论：分离自脓毒症患儿的金黄色葡萄球菌的生物膜形成增加，MRSA显著增加。agr组I是分离的金黄色葡萄球菌中的主要agr基因。此外，agrI是MRSA分离株中的主要基因，与生物膜形成显着相关。
方法：本研究是一项回顾性横断面研究，纳入了131名患有金黄色葡萄球菌引起的卫生保健相关败血症的儿童。通过微孔板法研究了分离的金黄色葡萄球菌形成生物膜的能力，通过圆盘扩散法的抗生素敏感性模式，并通过聚合酶链反应（PCR）对agr基因型进行分子测定。
结果：耐甲氧西林金黄色葡萄球菌（MRSA）的定义是70（53.4％）的分离株对头孢西丁抗生素盘的耐药性，而67（58％）的分离株的生物膜形成为阳性。对agr基因的分子研究表明，54(41.2%)，40（30.5%），27（20.6%），和10（7.5％）的研究分离株具有agrI，agrII,agrIII,和AGRIV，分别。在MRSA和甲氧西林敏感金黄色葡萄球菌（MSSA）之间的比较，MRSA的生物膜形成明显增加(65.7%，p=0.01）与MSSA（34.3％）相比，MRSA中agr基因型I的增加（68.6％，p=0.001)与MSSA中的agrI(9.8%)相比。与中心静脉导管的存在存在显着关联（51.4％，p=0.001）和尿路导尿管（81.4％，与MSSA儿童相比，MRSA儿童的p=0.001（21.3％，OR=3.9，95%CI=1.8-8.5和36.1%，OR=7.8，95%CI分别为3.5-17.3)。
结论：分离自脓毒症患儿的金黄色葡萄球菌的生物膜形成增加，MRSA显著增加。agr组I是分离的金黄色葡萄球菌中的主要agr基因。此外，agrI是MRSA分离株中的主要基因，与生物膜形成显着相关。
