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Introduction: Klebsiella pneumoniae, a common hospital- and community-acquired pathogen, is notorious for multidrug resistance. This study aimed to better understand the correlation of clinical presentation and microbiological characteristics of the isolates causing bloodstream infections (BSIs) in Taiwan. Methodology: We retrospectively collected 150 isolates derived from K. pneumoniae bacteremia patients in Taiwan in both 2014 and 2016. Clinical data, bacterial serotyping and drug susceptibility tests were comparatively analyzed. Results: Demographic data showed that diabetes mellitus (DM) was the most common underlying disease (44.0%). The overall 30-day mortality rate was 19.3%, and higher mortality was found in patients with malignancy than others (P = 0.023). Serotype distribution was diverse. The major isolates belonged to non-PCR-typeable serotypes (58.7%) associated with hospital-acquired infections (P = 0.007) and in non-DM patients (P < 0.001), while K2 and K20 significantly caused infections and in DM patients (P = 0.046 and P = 0.006, respectively); however, only K2 showed more community-acquired infection (P = 0.022) than other typeable serotypes. Resistance to antibiotics in clinical isolates in the year 2016 was > 24%, including cefazolin (54%), ampicillin-sulbactam (25%) and cefuroxime (25%). Susceptibility to gentamicin, flomoxef, and tigecycline reduced between the two time periods (2014 and 2016). However, the isolates remained highly susceptible to amikacin and ertapenem (> 95%). Conclusions: Patients with cancer had a higher 30-day mortality rate than others. Amikacin and ertapenem are the drugs of choice for the treatment of multidrug-resistant K. pneumoniae BSIs in Taiwan. [ABSTRACT FROM AUTHOR]

Objectives: Acinetobacter baumannii complex bacteremia has been identified increasingly in critical patients admitted in ICUs. Notably, A. baumannii complex bacteremia has a high mortality rate, yet the risk factors associated with mortality remain unclear and controversial. Design: Retrospective study. Setting: All adult ICUs at a tertiary care medical center. Patients: All patients with A. baumannii complex bacteremia admitted in 2009-2010. Interventions: None. Measurements and Main Results: Risk factors for mortality were analyzed. Bacterial isolates were identified by 16S-23S ribosomal RNA intergenic spacer region sequencing for genospecies and genotyped by pulsed-field gel electrophoresis. Carbapenemase genes were detected by polymerase chain reaction and sequencing. A total of 298 patients met the inclusion criteria, including 73 (24.5%) infected by imipenem-resistant A. baumannii complex. The overall 30-day mortality was 33.6% (100 of 298). Imipenem-resistant A. baumannii complex bacteremia specifically showed a high mortality (69.9%) and was associated with prior use of broad-spectrum antibiotics for more than 5 days for treating ventilator-associated pneumonia before the occurrence of bacteremia. Mortality was associated with inappropriate initial antimicrobial therapy, which was correlated with imipenem-resistant A. baumannii complex but not with any specific genospecies. ISAba1-blaOXA-23-ISAba1 (Tn2006) was found in most (66.7%, 40 of 68) imipenem-resistant A. baumannii (genospecies 2) and also spread beyond species border to all imipenem-resistant genospecies 3 (2), 13TU (2), and 10(1). Conclusions: For critical patients with A. baumannii complex infection, ventilator-associated pneumonia in particular, the selective pressure from prior use of broad-spectrum antibiotics for 5 days or more increased risk of subsequent imipenem-resistant A. baumannii complex bacteremia. To reduce mortality, rapid identification of imipenem-resistant A. baumannii complex and early initiation of appropriate antimicrobial therapy in these high-risk patients are crucial. [ABSTRACT FROM AUTHOR]

Salmonella enterica serotype Enteritidis infection remains a serious public health threat to humans. Salmonella Enteritidis phage type 4 (PT4) is a clone that has already caused a global pandemic for years. To investigate why PT34 becomes a subdominantly emerging phage type, molecular characterizations, including serotyping, pulsed-field gel electrophoresis (PFGE), phage typing, and plasmid profiling, were carried out on PT34. The results indicated that relative to PT4, PT34 contained an additional 32-kb DNA segment in PFGE and a 33-kb plasmid pSE34 in plasmid profiling. Southern blot hybridization showed that the DNA segment was the major part of pSE34. All of the S. Enteritidis PT34 clinical isolates possessed pSE34, while PT4 and PT21 did not. Sequencing analysis revealed that pSE34 is 32 950 bp long, with a G+C% content of 41.2%, and contains a total of 53 orfs. Transposon mutagenesis demonstrated that taxB, taxC, and the pilX operon on this plasmid participated in the process of conjugation. In virulence testing, PT34 that harbored pSE34, compared with PT4, showed no increased invasion to tissue culture cells in vitro. The presence of conjugative pSE34 in PT4 caused the conversion of phage type from PT4 to PT34, suggesting that the emergence of PT34 was a result of the introduction of the conjugative pSE34 into its common progenitor PT4. [ABSTRACT FROM AUTHOR]

The three N-terminal, tandemly arranged LysM motifs from a Bacillus subtilis cell wall hydrolase, LytE, formed a cell wall-binding module. This module, designated CWBMLytE, was demonstrated to have tight cell wall-binding capability and could recognize two classes of cell wall binding sites with fivefold difference in affinity. The lower-affinity sites were approximately three times more abundant. Fusion proteins with β-lactamase attached to either the N- or C-terminal end of CWBMLytE showed lower cell wall-binding affinity. The number of the wall-bound fusion proteins was less than that of CWBMLytE. These effects were less dramatic with CWBMLytE at the N-terminal end of the fusion. Both CWBMLytE and β-lactamase were essentially functional whether they were at the N- or C-terminal end of the fusion. In the optimal case, 1.2 × 107 molecules could be displayed per cell. As cells overproducing CWBMLytE and its fusions formed filamentous cells (with an average of nine individual cells per filamentous cell), 1.1 × 108β-lactamase molecules could be displayed per filamentous cell. Overproduced CWBMLytE and its fusions were distributed on the entire cell surface. Surface exposure and accessibility of these proteins were confirmed by immunofluorescence microscopy. [ABSTRACT FROM AUTHOR]

Fengycin, a lipopeptidic antibiotic, is synthesized nonribosomally by five fengycin synthetases (FenC, FenD, FenE, FenA, and FenB) in Bacillus subtilis F29-3. This work demonstrates that these fengycin synthetases interlock to form a chain, which coils into a 14.5-nm structure. In this chain, fengycin synthetases are linked in the order FenC-FenD-FenE-FenA-FenB by interactions between the C-terminal region of an upstream enzyme and the N-terminal region of its downstream partner enzyme, with their amino acid activation modules arranged colinearly with the amino acids in fengycin. This work also reveals that fengycin is synthesized on this fengycin synthetase chain, explaining how fengycin is synthesized efficiently and accurately. The results from this investigation demonstrate that forming a peptide synthetase complex is crucial to nonribosomal peptide synthesis. [ABSTRACT FROM AUTHOR]

Focuses on the production of clostridium cellulovorans engB. Interaction between dockerin domain and the cohesion domain; Preparation of active recombinant cellulosomes; Features of bacillus subtilis.

Focuses on the functional and transcriptional analyses of a fengycin synthetase gene, fenC, from Bacillus subtilis. Bacterial strains, plasmids and culture media; DNA sequencing; Primer extensions.

The use of pneumococcal vaccine plays an important role for prevention of invasive pneumococcal disease (IPD). However, introducing the pneumococcal vaccine into the national immunization program (NIP) is complex and costly. The strategy of progressively integrating the pneumococcal conjugate vaccine (PCV) into the NIP in Taiwan provides valuable experience for policy makers. The 7-valent PCV (PCV7) was first available in Taiwan in late 2005. PCV7 was first provided free to children with underlying diseases, those in vulnerable socioeconomic status, and those with inadequate health care resources. The catch-up immunization program with the 13-valent PCV was launched in 2013 and the national pneumococcal immunization program was implemented in 2015. Children aged 2-5 years had the highest incidence of IPD among pediatric population in Taiwan. Although the incidence of IPD caused by PCV7 serotypes has declined, the overall incidence of IPD remained high in the context of PCV7 use in the private sector. A surge of IPD caused by serotype 19A occurred, accounting for 53.6% of IPD cases among children aged ≤ 5 years in 2011-2012. After the implementation of the national pneumococcal immunization program, serogroup 15 has become the leading serogroup for IPD in children. Continued surveillance is necessary to monitor the serotype epidemiology in Taiwan. [ABSTRACT FROM AUTHOR]

Vancomycin-resistant Clostridium innocuum was recently identified as an etiologic agent for antibiotic-associated diarrhea in humans. We conducted a case-control study involving 152 C. innocuum-infected patients during 2014-2019 in Taiwan, using 304 cases of Clostridioides difficile infection (CDI) matched by diagnosis year, age (+2 years), and sex as controls. The baseline characteristics were similar between the 2 groups. C. innocuum-infected patients experienced more extraintestinal clostridial infection and gastrointestinal tract-related complications than did patients with CDI. The 30-day mortality rate among C. innocuum-infected patients was 14.5%, and the overall rate was 23.0%. Chronic kidney disease, solid tumor, intensive care unit admission, and shock status were 4 independent risk factors for death. C. innocuum identified from clinical specimens should be recognized as a pathogen requiring treatment, and because of its intrinsic vancomycin resistance, precise identification is necessary to guide appropriate and timely antimicrobial therapy. [ABSTRACT FROM AUTHOR]

In Taiwan, despite a substantial decline of Salmonella enterica serotype Choleraesuis infections, strains resistant to ciprofloxacin and ceftriaxone persist. A self-transferable blaCMY-2-harboring IncI1 plasmid was identified in S. enterica serotypes Choleraesuis, Typhimurium, Agona, and Enteritidis and contributed to the overall increase of ceftriaxone resistance in salmonellae. [ABSTRACT FROM AUTHOR]

Background The green fluorescence protein (GFP)-associated fluorescence method and the luciferaseassociated bioluminescence method are the two major methods for IVIS imaging system to investigate the bacterial infection in animal models. The aim of this study was to evaluate the infection route of Gram-negative bacteria carrying a stable and broad range of conjugative bioluminescence plasmid pSE-Lux1 in a mouse model. Results Both encapsulated and non-encapsulated Gram-negative bacteria were used as hosts to evaluate conjugation efficiency and plasmid stability of pSE-Lux1, a recombinant of pSE34 and luxABCDE operon. The plasmid conjugation efficiencies of pSE-Lux1 ranged from 10-3 to 10-7 in various Gram-negative bacteria. Plasmid pSE-Lux1 maintained in Escherichia coli, Klebsiella pneumoniae, and Salmonella enterica serovars Choleraesues (abbreviated S. Choleraesuis) and Typhimurium (S. Typhimurium), than in Acinetobacter baumannii and Serratia marcescens, was shown to be of better stability for at least four days. To investigate systemic bacterial infections, K. pneumoniae T strain CG354 was intravenous injected and was non-pathogenic to Balb/c mice for a long-term bioluminescence monitoring for 6 days. For examining dynamic distributions of gastrointestinal tract infection, the invasion protein SipB-deficient mutant OU5045ΔsipB and OU5046ΔsipB of Salmonella enterica serovar Typhimurium constructed in this study, compared to wild-type strain OU5045 and its virulence plasmid-less strain OU5046, were of less virulence to mice. Conclusions This is the first study to evaluate the conjugative and stable bioluminescence vehicle system of pSE-Lux1 in a wide range of Gram-negative bacteria, which system can provide a useful reporter approach to trace systemic and gastrointestinal bacterial infections in a mouse model. [ABSTRACT FROM AUTHOR]