Two bacterial infection models in tree shrew for evaluating the efficacy of antimicrobial agents

Animal models are essential for the development of new anti-infectious drugs.Although some bacterial infection models have been established in rodents,small primate models are rare.Here,we report on two bacterial infection models established in tree shrew（Tupaia belangeri chinensis）.A burnt skin infection model was induced by dropping 5×106 CFU of Staphylococcus aureus on the surface of a wound after a third degree burn.This dose of S.aureus caused persistent infection for 7 days and obvious inflammatory response was observed 4 days after inoculation.A Dacron graft infection model,2×106 CFU of Pseudomonas aeruginosa also caused persistent infection for 6 days,with large amounts of pus observed 3 days after inoculation.These models were used to evaluate the efficacy of levofloxacin（LEV） and cefoperazone（CPZ）,which reduced the viable bacteria in skin to 4log10 and 5log10 CFU/100 mg tissue,respectively.The number of bacteria in graft was significantly reduced by 4log10 CFU/mL treatment compared to the untreated group（P0.05）.These results suggest that two bacterial infection models were successfully established in tree shrew using P.aeruginosa and S.aureus.In addition,tree shrew was susceptible to P.aeruginosa and S.aureus,thus making it an ideal bacterial infection animal model for the evaluation of new antimicrobials.

破裂性腹主动脉瘤术后并发人工血管周围巨大脓肿一例

患者男，56岁。因“反复腰痛10d余，加重伴腹痛6h”，明确诊断为“破裂性腹主动脉瘤”于2006年11月20日第1次急诊入院行破裂性腹主动脉瘤切除、人工血管置换术，手术及术后康复均顺利，术后11d出院。出院8个月后患者出现反复低热伴左腰部隐痛，体温最高38℃，在当地医院给予抗生素治疗后未见好转再次至我院就诊，入院后查腹部CT检查示人工血管周围脓肿形成（图1，2）。血常规显示：白细胞计数：18．64×10^9／L，中性粒细胞：0．75。诊断性穿刺抽出淡黄色脓液，送细菌培养示金色葡萄球菌感染，药敏试验：对哌拉西彬舒巴坦及喹诺酮类抗生素敏感，

Anti-infectious efficacy of essential oil from Caoguo(Fructus Tsaoko)

OBJECTIVE: To evaluate the anti-infectious efficacy of essential oil extracted from Caoguo(Fructus Tsaoko).METHODS: Minimum inhibitory concentrations(MICs) against clinical isolates of three extracts andthe essential oil from Caoguo(Fructus Tsaoko) were determined by the agar dilution method. The anti-infectious efficacy of the essential oil was evaluated using a mouse peritonitis model which was infected with Staphylococcus aureus or Escherichia coli. The chemical components of the essential oil were identified.RESULTS: The results showed that the essential oil exhibited strong antibacterial activity in vitro, with MICs ranging from 22.49 to 1438.91 μg/m L. The results of in vivo anti-infectious efficacy showed that the Caoguo(Fructus Tsaoko) essential oil can protect the mice from Staphylococcus aureus or Escherichia coli infection. The compositions of the essential oil and relative component percentages were examined. A total of 32 compounds, were identified. The major compounds of essential oil were 1,8-cineole(25.92%) and geraniol(13.69%).CONCLUSION: Our findings suggest that Caoguo(Fructus Tsaoko) essential oil has broad-spectrum antibacterial properties. It warrants further investigation as an antibacterial agent targeting some bacterium with multi-drug resistance.

Selective inactivation of Gram-positive bacteria in vitro and in vivo through metabolic labelling

Bacterial infections are grave threats to human health,particularly those caused by the most common Grampositive bacteria.The massive administration of broad-spectrum antibiotics to treat various bacterial infections has led to the evolution and spread of drug resistance.As a universal antimicrobial technique unapt to induce drug resistance,photothermal therapy(PTT)is attracting extensive attention in recent years.However,its unspecific killing capability and side effects towards adjacent mammalian cells severely impede the practical applications.Herein,we proposed a metabolic engineering strategy to selectively inactivate Gram-positive bacteria by PTT.A bioorthogonal photothermal agent was prepared by the conjugation of IR-780 iodide and dibenzocyclooctyne(IR780-DBCO).Upon pre-metabolizing with 3-azido-D-alanine,Gram-positive bacteria rather than Gramnegative ones,such as Staphylococcus aureus and vancomycinresistant Enterococcus faecalis(VRE),could be specifically tied up by the explosive IR780-DBCO via copper-free click chemistry.Thereafter,they spontaneously detonated under 15 min near-infrared light irradiation and inactivated nearly 100% Gram-positive bacteria in vitro.Moreover,superbug VRE-induced infection was significantly inhibited by this approach in a mouse skin wound model.This metabolic labelling-based photothermal ablation strategy specific to Gram-positive microbes would stimulate the development of precise antibacterial candidates for preclinical applications.

A 61-year-old man with bloody purulent cerebrospinal fluid

Staphylococcus aureus meningitis(SAM)is a relatively uncommon but serious disease,accounting for only 1%–9%of cases of bacterial meningitis.In this report,we described a 61-year-old man,whose appearance of CSF was bloody and purulent.CSF test showed extremely elevated WBC count and protein quantification.Bacterial culture demonstrated SAM.Complications included septic shock,acute respiratory failure,and renal failure.Empiric antibiotic treatment was not effective for him.Therefore,we prescribed up to five types of antibiotics.We found that the clinical symptoms,CSF indicators,inflammatory markers,respiratory and renal function got better.The nerve function comparatively recovered well after 6 months of follow-up.