Gad Gamal Fadl Mahmoud, El-Feky Mohamed Ali, El-Rehewy Mostafa Said, Hassan Mona Amin, Abolella Hassan, El-Baky Rehab Mahmoud Abd
Microbiology Department, Faculty of Medicine, Assuit University, Assuit, Egypt.
J Infect Dev Ctries. 2009 Jun 1;3(5):342-51. doi: 10.3855/jidc.241.
Staphylococci are a common cause of catheter-associated urinary tract infections. The present study evaluated biofilm forming capacity and the presence of both icaA and icaD genes among staphylococci strains isolated from patients undergoing ureteral catheterization.
Different bacterial strains were isolated from urine and stents segments collected from 100 patients. Strains were identified by traditional microbiological methods. Stents were examined for biofilm using a scanning electron microscope (SEM). Staphylococcal isolates were tested for their ability to produce biofilm using the tissue culture plate assay method (TCP). The presence of icaA and icaD genes was determined by PCR technique.
Fifty-three staphylococcal strains were isolated and identified from 284 samples (18.7%). Forty-six staphylococcal strains were isolated from stent segment cultures while only seven strains were isolated from urine samples at the day of stent removal. S. aureus represented 6.3%, and S. epidermidis represented 12.3%. Out of the 18 S. aureus strains, 15 (83.3%) were biofilm producers and out of 35 S. epidermidis strains, 31 (88.6%) were biofilm producers. Staphylococcal strains were further classified as high (56.6%), moderate (30.2%) and non biofilm producers (13.2%). All biofilm producing strains were positive for icaA and icaD genes, and all biofilm negative strains were negative for both genes.
Staphylococci isolated from catheter segments showed a higher extent of biofilm production than that isolated from urine samples. All biofilm producing staphylococci were positive for icaA and icaD genes, which indicates the important role of ica genes as virulence markers in staphylococcal infections associated with urinary catheterization.
葡萄球菌是导管相关尿路感染的常见病因。本研究评估了从接受输尿管插管的患者中分离出的葡萄球菌菌株的生物膜形成能力以及icaA和icaD基因的存在情况。
从100例患者的尿液和支架段中分离出不同的细菌菌株。通过传统微生物学方法鉴定菌株。使用扫描电子显微镜（SEM）检查支架上的生物膜。采用组织培养板检测法（TCP）检测葡萄球菌分离株产生生物膜的能力。通过PCR技术确定icaA和icaD基因的存在情况。
从284份样本中分离并鉴定出53株葡萄球菌菌株（18.7%）。从支架段培养物中分离出46株葡萄球菌菌株，而在支架取出当天仅从尿液样本中分离出7株菌株。金黄色葡萄球菌占6.3%，表皮葡萄球菌占12.3%。在18株金黄色葡萄球菌菌株中，15株（83.3%）为生物膜产生菌，在35株表皮葡萄球菌菌株中，31株（88.6%）为生物膜产生菌。葡萄球菌菌株进一步分为高生物膜产生菌（56.6%）、中度生物膜产生菌（30.2%）和非生物膜产生菌（13.2%）。所有生物膜产生菌的icaA和icaD基因均为阳性，所有生物膜阴性菌株的这两个基因均为阴性。
从导管段分离出的葡萄球菌比从尿液样本中分离出的葡萄球菌表现出更高程度的生物膜产生。所有产生生物膜的葡萄球菌的icaA和icaD基因均为阳性，这表明ica基因作为毒力标志物在与导尿管相关的葡萄球菌感染中起重要作用。
