[New eudesmane sesquiterpenoids from Atractylodis Macrocephalae Rhizoma and their inhibitory activities against SREBPs].

Three sesquiterpenoids were isolated and purified from the 95% ethanol extract of Atractylodis Macrocephalae Rhizoma by column chromatography on silica gel, Sephadex LH-20, ODS, and high-performance liquid chromatography(HPLC). Their chemical structures were identified on the basis of spectroscopic analysis and physiochemical properties as(7Z)-8ß,13-diacetoxy-eudesma-4(15),7(11)-diene(1), 7-oxo-7,8-secoeudesma-4(15),11-dien-8-oic acid(2), and guai-10(14)-en-11-ol(3). Compounds 1 and 2 are new compounds and compound 3 was obtained from Compositae family for the first time. Compounds 1, 2, and 3 showed weak inhibitory activities against sterol regulatory element-binding proteins(SREBPs).

Identification of a Depolymerase Specific for K64-Serotype Klebsiella pneumoniae: Potential Applications in Capsular Typing and Treatment.

Carbapenem-resistant Klebsiella pneumoniae (CRKP), one of the major nosocomial pathogens, is increasingly becoming a serious threat to global public health. There is an urgent need to develop effective therapeutic and preventive approaches to combat the pathogen. Here, we identified and characterized a novel capsule depolymerase (K64-ORF41) derived from Klebsiella phage SH-KP152410, which showed specific activities for K. pneumoniae K64-serotype. We showed that this depolymerase could be used in the identification of K64 serotypes based on the capsular typing, and the results agreed well with those from the conventional serotyping method using antisera. From this study, we also identified K64 mutant strains, which showed typing discrepancy between wzi-sequencing based genotyping and depolymerase-based or antiserum-based typing methods. Further investigation indicated that the mutant strain has an insertion sequence (IS) in wcaJ, which led to the alteration of the capsular serotype structure. We further demonstrated that K64-ORF41 depolymerase could sensitize the bacteria to serum or neutrophil killing by degrading the capsular polysaccharide. In summary, the identified K64 depolymerase proves to be an accurate and reliable tool for capsular typing, which will facilitate the preventive intervention such as vaccine development. In addition, the polymerase may represent a potential and promising therapeutic biologics against CRKP-K64 infections.

Identification of a novel phage targeting methicillin-resistant Staphylococcus aureus In vitro and In vivo.

INTRODUCTION: Staphylococcus aureus is a common human pathogen that causes various diseases including infections on the skin, in the bloodstream and the lower respiratory tracts. The emergence of methicillin-resistant S. aureus (MRSA) made the treatment of the bacterial infection more difficult, calling for development of new therapeutics. Compared with conventional antibiotic therapy, phage therapy offers a promising alternative to combat infections caused by MRSA. RESULTS: Here we showed that phage VB_SauS_SH-St 15644 isolated from sewage inhibited MRSA isolates in vitro and in the murine skin infection model. Phage VB_SauS_SH-St 15644 belongs to Siphoviridae. The genome of the phage is a linear, 45,111 bp double-stranded DNA with GC content of 33.35%. Among the 37 clinical MRSA isolates tested, 12 (32%) were lysed by the phage in vitro. The phage was relatively stable at temperatures up to 40 °C or between pH 6 and 9. However, the phage was sensitive to UV light. 80% of the phage was approximately adsorbed to the host MRSA isolate in 4 min. The one-step growth curve showed that the latent period was about 12 min followed by the growth period (about 9 min). The burst size was estimated at 13 PFU per infected cell. Furthermore, in a murine skin infection model, the phage significantly inhibited MRSA infection. CONCLUSIONS: Our study suggested that phage VB_SauS_SH-St 15644 has a potential to inhibit MRSA skin infection.

A Novel Polysaccharide Depolymerase Encoded by the Phage SH-KP152226 Confers Specific Activity Against Multidrug-Resistant Klebsiella pneumoniae via Biofilm Degradation.

The increasing prevalence of infections caused by multidrug-resistant Klebsiella pneumoniae necessitates the development of alternative therapies. Here, we isolated, characterized, and sequenced a K. pneumoniae bacteriophage (SH-KP152226) that specifically infects and lyses K. pneumoniae capsular type K47. The phage SH-KP152226 contains a genome of 41,420 bp that encodes 48 predicted proteins. Among these proteins, Dep42, the gene product of ORF42, is a putative tail fiber protein and hypothetically possesses depolymerase activity. We demonstrated that recombinant Dep42 showed specific enzymatic activities in the depolymerization of the K47 capsule of K. pneumoniae and was able to significantly inhibit biofilm formation and/or degrade formed biofilms. We also showed that Dep42 could enhance polymyxin activity against K. pneumoniae biofilms when used in combination with antibiotics. These results suggest that combination of the identified novel depolymerase Dep42, encoded by the phage SH-KP152226, with antibiotics may represent a promising strategy to combat infections caused by drug-resistant and biofilm-forming K. pneumoniae.

Phage Therapy as a Promising New Treatment for Lung Infection Caused by Carbapenem-Resistant Acinetobacter baumannii in Mice.

Carbapenem-resistant Acinetobacter baumannii (CRAB) which is noted as a major pathogen associated with healthcare-associated infections has steadily developed beyond antibiotic control. Lytic bacteriophages with the characteristics of infecting and lysing specific bacteria have been used as a potential alternative to traditional antibiotics to solve multidrug-resistant bacterial infections. Here, we isolated A. baumannii-specific lytic phages and evaluated their potential therapeutic effect against lung infection caused by CRAB clinical strains. The combined lysis spectrum of four lytic phages' ranges was 87.5% (42 of 48) against CRAB clinical isolates. Genome sequence and analysis indicated that phage SH-Ab15519 is a novel phage which does not contain the virulence or antibiotic resistance genes. In vivo study indicated that phage SH-Ab15519 administered intranasally can effectively rescue mice from lethal A. baumannii lung infection without deleterious side effects. Our work explores the potential use of phages as an alternative therapeutic agent against the lung infection caused by CRAB strains.