小肠结肠炎耶氏菌体外毒力试验

为了初步研究小肠结肠炎耶氏菌（Ｙ．ｅ．）致病机理，本文报告应用依钙、自凝、刚果红平板毒力试验和质粒ＤＮＡ提取方法，进行Ｙ．ｅ．体外毒力探讨。结果表明：带毒力质粒的Ｙ．ｅ．菌株Ｇ１５１，９２０和ＬＡＢ－Ｂ１８２依钙、自凝和刚果红平板毒力试验阳性；不带毒力质粒的Ｙ．ｅ．菌株８２－１４０和４３９－８０Ｖ￣－依钙、自凝和刚果红平板毒力试验阴性。依钙、自凝、刚果红平板毒力试验阳性与携带毒力质粒的一致性以及依钙、自凝、刚果红平板毒力试验阴性与不携带毒力质粒的一致性表明：Ｙ．ｅ．的依钙、自凝和吸收刚果红特性是毒力质粒编码。

刚果红平板法筛选血链球菌胞外多糖缺失突变株

细菌胞外多糖不但能够保护细菌,防止外界环境变化和侵蚀者对菌体细胞的侵害,而且在医学微生物学中还具有特有的生物学活性,包括抗辐射、抗氧化等特性。尽管细菌胞外多糖受到了学者的广泛关注,但胞外多糖的生物合成机制还不十分清楚。以血链球菌为模式生物,以随机插入突变机制构建的血链球菌胞外多糖形成基因文库为受试对象,建立了一种简单易行的刚果红平板法用于筛选血链球菌细胞外粘多糖形成缺失突变株的方法,为日后研究细菌胞外多糖形成机制以及临床上筛选胞外多糖缺失突变株奠定了基础。

In vitro anti-biofilm and anti-bacterial activity of Junceella juncea for its biomedical application

Objective:To investigate the anti-biofilm and anti-bacterial activity of Junceella juncea(J.juncea)against biofilm forming pathogenic strains.Methods:Gorgonians were extraeted with methanol and analysed with fourier transform infrared spectroscopy.Biofilm forming pathogens were identified by Congo red agar supplemented with sucrose.A quantitative spectrophotometric method was used to monitor in vitro biofilm reduction by microtitre plate assay.Anti-bacterial activity of methanolic gorgonian extract(MGE)was carried out by disc diffusion method followed by calculating the percentage of increase with crude methanol(CM).Results:The presence of active functional group was exemplified by FT-IR spectroscopy.Dry,black,crystalline colonies confirm the production of extracellular polymeric substances responsible for biofilm formation in Congo red agar.MGE exhibited potential anti-biofilm activity against all tested bacterial strains.The anti-bacterial activity of methanolic extract was comparably higher in Salmonella typhii followed by Escherichia colt,Vibrio cholerae and Shigella flexneri.The overall percentage of increase was higher by 50.2%to CM.Conclusions:To conclude,anti-biofilm and anti-bacterial efficacy of J.juncea is impressive over biofilm producing pathogens and are good source for novel anti-bacterial compounds.

Molecular Detection of Biofilm-Producing <i>Staphylococcus aureus</i>Isolates from National Orthopaedic Hospital Dala, Kano State, Nigeria

This study evaluated biofilm formation and antibiotic susceptibility in 36 clinical S. aureus isolates recovered from orthopaedic patients and detected the presence of intercellular adhesion and adhesin genes. Staphylococcus aureus was isolated from nasal swab, wound and urine specimens collected from orthopaedic patients in National Orthopaedic Hospital Dala, Kano over a period of three months. The isolates were identified using rapid identification kit for Staphylococcus species. The antibiotics susceptibility of the isolates was determined using modified disc diffusion method. Phenotypically, the biofilm formation was assessed using the Congo red agar method and microtitre plate assay. Polymerase chain reaction (PCR) analysis was used to detect biofilm-associated genes and characterize the isolates. The isolation rate of S. aureus from the samples (n = 134) was 26.8%, mainly from nasal swab (36%) and wound swab (36%). A total of 19 (52.7%) of the isolates showed positive for slime production. Majority of the isolates 29/36 (81.6%) were biofilm positive with only 2 (5.5%) and 5 (13.8%) as strong biofilm-formers and moderate biofilm-formers respectively. Molecular evaluation of the biofilm-associated genes in 12 S. aureus isolates revealed the prevalence of bbp genes (25%), clfA genes (16.6%) and the icaA (8.3%). None of the isolates harboured the fnbA and cna genes. There is no significant difference (P > 0.05) in the antibiotic resistance pattern between biofilm-positive and biofilm-negative S. aureus isolates. This result revealed that phenotypically most of the S. aureus isolates were biofilm formers but few of them chromosomally harbour the biofilm-associated genes.

In vitro biofilm forming capacity on abiotic contact surfaces by outbreak-associated Vibrio harveyi strains

Objective:To evaluate the in vitro biofilm forming capacity on abiotic food contact surfaces by Vibrio harveyi(V.harveyi)strains.Methods:Thirty six Gram-negative V.harveyi strains were isolated from various street vended seafood outlets in a food processing line and evaluated for their ability to produce mucoid biofilms on food contact surfaces using a microplate assay.Phenotypic characterization of mucoid biofilm producing V.harveyi strains were screened on Congo red agar,thiosulfate-citrate-bile salts-sucrose agar and tryptic soy agar,respectively.Results:Only five V.harveyi strains(14%)were mucoid biofilm producers characterized by formation of black colonies,whereas the remaining 31 strains(86%)were not capable of producing biofilm characterized by formation of red colonies or pinkish-red colonies with darkening at the centre.The morphological,physiological and biochemical characteristics of these isolates were studied using standard protocols.Strain identification was confirmed by polymerase chain reaction targeted to species-specific polymerase chain reaction primers VH-1 and VH-2 corresponding to variable regions of V.harveyi 16S rRNA sequence.All the biofilm-forming strains showed resistance to at least three antimicrobial compounds tested.V.harveyi strains isolated from various seafood were able to form biofilms of different capacity,and the strains VB267,VB238 and VB166 isolated from cat fish,shrimp and eel fish exhibited significantly greater biofilm forming ability compared to other isolates.Conclusions:It can be concluded from the present study that the strain VB166 was able to better attach and form subsequent biofilms on glass and stainless steel compared to high density polyethylene.These properties allow these bacteria to survive,proliferate and persist in street vended seafood outlets.