Dysbiosis of gut microbiota is closely related to occurrence of many important chronic inflammations-related diseases. So far the traditionally prescribed prebiotics and probiotics do not show significant impact on amelioration of these diseases in general. Thus the development of next generation prebiotics and probiotics designed to target specific diseases is urgently needed. In this review, we first make a brief introduction on current understandings of normal gut microbiota, microbiome, and their roles in homeostasis of mucosal immunity and gut integrity. Then, under the situation of microbiota dysbiosis, development of chronic inflammations in the intestine occurs, leading to leaky gut situation and systematic chronic inflammation in the host. These subsequently resulted in development of many important diseases such as obesity, type 2 diabetes mellitus, liver inflammations, and other diseases such as colorectal cancer (CRC), obesity-induced chronic kidney disease (CKD), the compromised lung immunity, and some on brain/neuro disorders. The strategy used to optimally implant the effective prebiotics, probiotics and the derived postbiotics for amelioration of the diseases is presented. While the effectiveness of these agents seems promising, additional studies are needed to establish recommendations for most clinical settings.

dKlebsiella pneumoniae is an important human pathogen associated with a variety of diseases, and the prevalence of multidrugresistant K. pneumoniae (MDRKP) is rapidly increasing. Here we determined the capsular types of 85 carbapenem-resistant K. pneumoniae (CRKP) strains by wzc sequencing and investigated the presence of carbapenemases and integrons among CRKP strains. Ten CRKP strains (12%) were positive for carbapenemase (imipenemase, 6/85 strains; K. pneumoniae carbapenemase, 3/85 strains; Verona integron-encoded metallo-␤-lactamase, 1/85 strains). Capsular type K64 accounted for 32 CRKP strains (38%), followed by K62 (13%), K24 (8%), KN2 (7%), and K28 (6%). Sequence types (STs) were determined by multilocus sequence typing (MLST), and the results indicated that ST11, which accounted for 47% of these CRKP strains (40/85 strains), was the major ST. We further isolated a K64-specific capsule depolymerase (K64dep), which could enhance serum and neutrophil killing in vitro and increase survival rates for K64 K. pneumoniae-inoculated mice. The toxicity study demonstrated that mice treated with K64dep showed normal biochemical parameters and no significant histopathological changes of liver, kidney, and spleen, indicating that enzyme treatment did not cause toxicity in mice. Therefore, the findings of capsular type clustering among CRKP strains and effective treatment with capsule depolymerase for MDRKP infections are important for capsule-based vaccine development and therapy.K lebsiella pneumoniae, a Gram-negative bacillus, causes hospital or community-acquired disease (1-3). Most K. pneumoniae strains harbor chromosome-encoded SHV ␤-lactamase (4). In 1983, the emergence of K. pneumoniae strains producing a mutant of SHV-1 ␤-lactamase that hydrolyzes extended-spectrum cephalosporins was observed in Germany (5); subsequently, K. pneumoniae strains resistant to third-generation cephalosporins were detected in France, and a new ␤-lactamase gene closely related to TEM-1 and TEM-2 was identified (6). In 1989, the CTX-M type was reported as a new extended-spectrum ␤-lactamase (ESBL) family member not belonging to either the TEM type or the SHV type (7), and subsequently it was considered one of the major ESBL types (8). Recent global surveillance data from Europe, North and South America, and Asia revealed that the frequency of ESBL-producing K. pneumoniae was 7.5 to 44% (9). As the prevalence of ESBL-producing isolates increased, carbapenems were used to treat serious infections caused by ESBL-producing K. pneumoniae. However, carbapenem-resistant K. pneumoniae (CRKP) rates have been dramatically increasing worldwide over the past 10 years. In the United States, a significant increase in CRKP prevalence from Ͻ1% in 2000 to 8% in 2007 was reported (10). In addition, data from the National Healthcare Safety Network (NHSN) showed that, in 2006 and 2007, CRKP was reported for up to 10.8% of total isolates associated with certain device-related infections (11). In Italy, CRKP increased rapidly from 1 to 2% in 2006 to 2009...

ObjectiveChronic obstructive pulmonary disease (COPD) is a global disease characterised by chronic obstruction of lung airflow interfering with normal breathing. Although the microbiota of respiratory tract is established to be associated with COPD, the causality of gut microbiota in COPD development is not yet established. We aimed to address the connection between gut microbiota composition and lung COPD development, and characterise bacteria and their derived active components for COPD amelioration.DesignA murine cigarette smoking (CS)-based model of COPD and strategies evaluating causal effects of microbiota were performed. Gut microbiota structure was analysed, followed by isolation of target bacterium. Single cell RNA sequencing, together with sera metabolomics analyses were performed to identify host responsive molecules. Bacteria derived active component was isolated, followed by functional assays.ResultsGut microbiota composition significantly affects CS-induced COPD development, and faecal microbiota transplantation restores COPD pathogenesis. A commensal bacterium Parabacteroides goldsteinii was isolated and shown to ameliorate COPD. Reduction of intestinal inflammation and enhancement of cellular mitochondrial and ribosomal activities in colon, systematic restoration of aberrant host amino acids metabolism in sera, and inhibition of lung inflammations act as the important COPD ameliorative mechanisms. Besides, the lipopolysaccharide derived from P. goldsteinii is anti-inflammatory, and significantly ameliorates COPD by acting as an antagonist of toll-like receptor 4 signalling pathway.ConclusionThe gut microbiota–lung COPD axis was connected. A potentially benefial bacterial strain and its functional component may be developed and used as alternative agents for COPD prevention or treatment.

The genome of the multihost bacteriophage ⌽K64-1, capable of infecting Klebsiella capsular types K1, K11, K21, K25, K30, K35, K64, and K69, as well as new capsular types KN4 and KN5, was analyzed and revealed that 11 genes (S1-1, S1-2, S1-3, S2-1, S2-2, S2-3, S2-4, S2-5, S2-6, S2-7, and S2-8) encode proteins with amino acid sequence similarity to tail fibers/spikes or lyases. S2-5 previously was shown to encode a K64 capsule depolymerase (K64dep). Specific capsule-degrading activities of an additional eight putative capsule depolymerases (S2-4 against K1, S1-1 against K11, S1-3 against K21, S2-2 against K25, S2-6 against K30/K69, S2-3 against K35, S1-2 against KN4, and S2-1 against KN5) was demonstrated by expression and purification of the recombinant proteins. Consistent with the capsular type-specific depolymerization activity of these gene products, phage mutants of S1-2, S2-2, S2-3, or S2-6 lost infectivity for KN4, K25, K35, or K30/K69, respectively, indicating that capsule depolymerase is crucial for infecting specific hosts. In conclusion, we identified nine functional capsule depolymerase-encoding genes in a bacteriophage and correlated activities of the gene products to all ten hosts of this phage, providing an example of type-specific host infection mechanisms in a multihost bacteriophage.IMPORTANCE We currently identified eight novel capsule depolymerases in a multihost Klebsiella bacteriophage and correlated the activities of the gene products to all hosts of this phage, providing an example of carriage of multiple depolymerases in a phage with a wide capsular type host spectrum. Moreover, we also established a recombineering system for modification of Klebsiella bacteriophage genomes and demonstrated the importance of capsule depolymerase for infecting specific hosts. Based on the powerful tool for modification of phage genome, further studies can be conducted to improve the understanding of mechanistic details of Klebsiella phage infection. Furthermore, the newly identified capsule depolymerases will be of great value for applications in capsular typing.KEYWORDS Klebsiella, bacteriophage, capsular type, capsule depolymerase, multiple host T he genus Klebsiella, especially the species Klebsiella pneumoniae, is an important human pathogen that causes a wide range of diseases, including both community and hospital-acquired infections. It is associated with septicemia, pneumonia, and urinary tract infections (1, 2) and also is responsible for a globally emerging disease, pyogenic liver abscess complicated with metastatic meningitis and endophthalmitis (3,4).Klebsiella spp. typically display a layer of thick, polysaccharide-based capsule on their surfaces. The expression of diverse capsule structure caused by different sugar compositions and linkages divide them into distinct serotypes. In addition, genetic

Colistin is one of the antibiotics of last resort for the treatment of carbapenem-resistant Klebsiella pneumoniae infection. This study showed that capsular type K64 (50%) and ST11 (53.9%) are the prevalent capsular and sequence types in the colistin-resistant strains in Taiwan. The interruption of transcripts (38.5%) and amino acid mutation (15.4%) in mgrB are the major mechanisms contributing to colistin resistance. In addition, novel single amino acid changes in MgrB (Stop48Tyr) and PhoQ (Leu26Pro) were observed to contribute to colistin resistance. Klebsiella pneumoniae is an important human pathogen that causes several hospital-acquired and community-acquired diseases (1, 2). Although carbapenem is generally used to treat infections caused by extended-spectrum ␤-lactamase (ESBL)-carrying K. pneumoniae (3), K. pneumoniae strains carrying carbapenemases or ESBL strains combined with the loss of porins can result in carbapenem-resistant K. pneumoniae (CRKP) (4-6). To eradicate CRKP, colistin and tigecycline are typically used to treat patients (7). Unfortunately, resistance to colistin and tigecycline has also been reported, with a 17% resistance rate of CRKP to colistin in Taiwan (8). A surveillance study also revealed that 43% of carbapenemase-producing K. pneumoniae isolates were resistant to colistin in Italy (9).Colistin, also called polymyxin E, is a cationic antimicrobial peptide that targets bacterial lipopolysaccharide (LPS), causing cell membrane leakage (10). Previous studies have demonstrated that the modification of lipid A with 4-amino-4-deoxy-L-arabinose (Ara4N) and phosphoethanolamine neutralizes the negative charge and reduces susceptibility to colistin in Enterobacteriaceae (11)(12)(13)(14)(15). Modification of Ara4N is achieved by the pmrHFIJKLM operon (13), and the two-component systems PhoPQ and PmrAB with connector PmrD are involved in the regulation of the pmrHFIJKLM operon (16,17). Moreover, MgrB is a negative regulator that influences PhoQ-PhoP phosphorylation (18)(19)(20). In this study, we analyzed capsular type and multilocus sequence type (MLST) distribution of colistin-resistant K. pneumoniae in Taiwan and attempted to define the mechanisms of resistance to colistin.Colistin-resistant K. pneumoniae strains were retrospectively collected from patients in the Taipei Veterans General Hospital (VGH) from February to August 2013. All 26 strains were clinical isolates and were isolated from different patients. Among the 26 clinical isolates, the Col14 and Col40 strains were CRKP, and only the Col14 strain harbored the carbapenemase KPC. Colistin was used to treat infections in 16 of the 26 patients prior to the isolation of strains, and the other patients did not receive colistin in the VGH (Table 1). However, we could not trace the colistin usage of these patients in other hospitals. Previous studies also showed that some colistin-resistant strains are isolated from healthy individuals (21). Resistance to colistin in strains that were not exposed to colistin might be due to spontaneous...