门诊男性泌尿生殖道葡萄球菌感染的临床监测分析

目的了解门诊男性泌尿道凝固酶阴性葡萄球菌和金黄色葡萄球菌菌种分布及蓟敏情况。方法回顾2004.11～2006.11门诊男性泌尿道分离的葡萄球菌菌种鉴定和K-B法药敏实验结果。结果耐甲氧西林葡萄球曲(MRS)为39株(28.5%),凝固酶阴性的葡萄球菌(CNS)109株占(79.6%)金黄色葡萄球菌(SAU)28株(20.4%),耐甲氧西林葡萄球菌存在严重交叉耐药。耐甲氧西林葡萄球菌和非耐甲氧西林葡萄球菌对万古霉素100%敏感,对利福平和呋喃妥因敏感率分别为92.3～95.9%,87.2～92.9%。结论凝固酶阴性的葡萄球菌为主要致病菌,万古霉素,利福平和呋喃妥因为治疗泌尿道葡萄球菌感染的首选药物。

Depression of biofilm formation and antibiotic resistance by sarA disruption in Staphylococcus epidermidis

AIM： To study the effects of disruption of sarA gene on biofilm formation and antibiotic resistance of Staphylococcus epidermidis （ S. epiderrnidis）. METHODS： In order to disrupt sarA gene, the double- crossover homologous recombination was applied in S. epiderrnidis RP62A, and tetracycline resistance gene （tet） was used as the selective marker which was amplified by PCR from the pBR322 and inserted into the locus between sarA upstream and downstream, resulting in pBT2ΔsarA. By electroporation, the plasmid pBT2ΔsarA was transformed into S. epiderrnidis. Gene transcription was detected by real-time reverse transcription-PCR （RT-PCR）. Determination of biofilm was performed in 96-well flat-bottomed culture plates, and antibiotic resistance was analyzed with test tube culture by spectrophotometry at 570 nm respectively. RESULTS： A sarA disrupted strain named S. epiderrnidis RP62AΔsarA was constructed, which was completely defective in biofilm formation, while the sarA complement strain RP62AΔsarA （pHPS9sarA） restored the biofilm formation phenotype. Additionally, the knockout of sarA resulted in decreased erythromycin and kanamycin resistance of S. epiderrnidis RP62A. Compared to the original strain, S. epiderrnidis RP62AΔsarA had an increase of the sensitivity to erythromycin at 200-400 μg/mL and kanamycin at 200-800 μg/mL respectively. CONCLUSION： The knockout of sarA can result in the defect in biofilm formation and the decreased erythromycin and kanamycin resistance in S. epiderrnidis RP62A.

High Prevalence of Multidrug-Resistance MRSA and VRSA of Different Infections from AI-Jumhuory Teaching Hospital Patients in Mosul

Staphylococcus aureus is major human pathogen causing large variety of infections worldwide. This study carried out to isolate S. aureus from different clinical cases, also detection of MRSA prevalence and VRSA emergence, in addition to shedding light on strains that have to be multidrug resistance against various antibiotics, The clinical samples were collected from AI-Jumhuory Teaching Hospital patients in Mosul, isolates identification were achieved by conventional procedures including biochemical and physiological tests, and the specific latex agglutination test. The sensitivity pattern achieved by using disk diffusion technique, for MRSA and VRSA detection oxacillin-disk （1 μg） and vancomycin-disk （30 μg） were used respectively. Results revealed, among 17 S. aureus isolates, 7 （41%） were mostly isolated from patients with wound and burn infections. Isolates had high resistance rate against ampicillin （100%） and cefotaxime （81%）, and lower resistance rate against several antibiotics. MRSA was 88% of total isolates, 93.3% of MRSA were multidrug resistance to 3-9 of antibiotics. Six isolates （40%） of MRSA were VRSA. It is concluded that antibiotics other than vancomycin can be used as anti-MRSA agents after a sensitivity test to prevent the prevalence of VRSA, the major cause of this chemotherapy problems maybe irrational and indiscriminate use of broad-spectrum antibiotics.

Analysis of the Clinical Characteristics and Antibiotics Resistance of Community-acquired Methicillin-resistant Staphylococcus aureus

The purpose of this investigation is to study the clinical characteristics of infections by community-acquired methicillin-resistant Staphylococcus aureus (MRSA) and the condition of antibiotics resistance of the clinical isolates in order to guide for the rational use of antibiotics. With the clinical isolates from cases of hospital-acquired MRSA at the same period as controls, the clinical characteristics of infections by community-acquired MRSA in Hangzhou area and the pattern of non-β-lactamase antibiotics resistance were determined in this study. It was found that the average age of patients with community-acquired MRSA infections was 30.89±13.3, in comparison with those of the hospital-acquired patients of 56.0±11.8, appearing to be younger than those of the latter, and the former showing no any basic illness. Both of the former and the latter were sensitive to vancomycin (100% vs 100%), and they had the same degrees of sensitivity to rifampicin, fosfomycin, and STM/TMP (86.8% vs 88.1%, P >0.05; 81.6% vs 82.9%, P >0.05; and 52.6% vs 61.9%, P >0.05, respectively). The former was more sensitive to netimycin, clindamycin, erythromycin and minocycline than those of the latter (73.7% vs 50.5%, P <0.01; 60.5% vs 45.7%, P <0.05; 28.9% vs 11.4%, P <0.01; and 81.6% vs 58.6%, P <0.01 respectively). Meanwhile, the incidence of multi-resistant strain of isolates in the former was significantly lower than that of the latter (31.6% vs 81.0%, P <0.01). In conclusion, it appears that the strains of clinical isolates isolated from patients with the community-acquired MRSA infections show different clinical characteristics and antimicrobial susceptibility in comparison with those of the hospital-acquired cases of infection, and this necessitates an alteration in the chemotherapy of infections suspected to be caused by community-acquired MRSA.

Preparation and evaluation of liposomal clarithromycin with antimicrobial effect

In this study, we developed a novel liposomal delivery system modified by Tat peptide and wheat germ agglutinin（WGA） with antimicrobial effect. Physicochemical parameters, in vitro antimicrobial, time-kill study, cellular uptake, biofilm formation inhibition and in vivo antibacterial efficacy against Methicillin-resistant Staphylococcus aureus（MRSA） were investigated. Minimum inhibitory concentrations（MICs） and colony-forming units（CFUs） in the time-kill study for Tat-WGA-modified liposomal clarithromycin（CLA-Tat WGALip） were lower than those of free and other modified liposomal CLA. Flow cytometry analysis disclosed that Tat WGALip delivered more coumarin 6 into bacteria. Furthermore, Tat-WGA-modified liposomal CLA efficiently inhibited the formation of MRSA biofiom. CFU of MRSA in the abscess of mice treated with CLA-Tat WGALip was significantly lower than that of any others（P〈0.01）. Collectively, liposomal delivery system modified by Tat and WGA could be a promising anti-resistant infection strategy.

New strategy for reversing biofilm-associated antibiotic resistance through ferrocene-substituted carborane ruthenium(Ⅱ)-arene complex

Bacterial biofilms are inherently resistant to antimicrobial agents and are difficult to eradicate with conventional antimicrobial agents, resulting in many persistent and chronic bacterial infections. In this contribution, a new strategy for reversing the biofilm-associated antibiotic resistance has been explored by induction of a carborane ruthenium(II)-arene complex (FcRuSB). Our results demonstrate that the FcRuSB could be utilized as an inducer to efficiently reverse the biofilm-associated antibiotic resistance of multidrug-resistant (MDR) clinical isolates of Staphylococcus aureus and Pseudomonas aeruginosa. The induced effect of FcRuSB is correlated with a considerable decrease in the expression of extracellular matrix proteins (EMP) of the two strains. The considerable decrease of the EMP of induced cells, resulting in the reduction of adherence and biofilm formation ability of the two types of MDR pathogens, and then can cause significantly enhanced sensitivity of them to antibiotics.