Characterization and genome analysis of a broad lytic spectrum bacteriophage P479 against multidrug-resistant Escherichia coli.

The increase of multi-drug resistant and multi-serotypes of pathogenic Escherichia coli has brought more severe challenge to control infection. Nowadays, bacteriophage is a promising tool to treat colibacillosis as an alternative of antibiotics. A coliphage P479, isolated from sewage of poultry farm, could lyse multiple serotypes, including not only O1, O2, O8, O9, O21, O78, O83, O145 of Avian pathogenic E. coli, but O157:H7 of Enterohaemorrhagic E. coli and O18:K1:H7 Neonatal meningitis E. coli. Additionally, P479 could also lyse multi-drug resistant E. coli. These indicated that P479 had good lytic ability. One-step growth curve revealed that the latent time period of P479 was 10 min and the burst size was about 318 PFU/cell. Stability tests demonstrated that P479 had good stability under various temperature (4 to 50 °C) and pH (3 to11) conditions. P479 contained of a linear, double-stranded DNA molecule of 172,033 bp with 40.3% GC content. P479 contained 296 putative coding sequences (CDSs) and two tRNA genes. Based on genomic comparison, P479 was classified as a member of genus Gaprivervirus, subfamily Tevenvirinae, family Myoviridae, order Caudovirales. No known virulent or lysogenic genes were detected in the genome of P479, manifesting P479 was safe to adhibit. Antibacterial activity in vitro manifested that P479 has varying degrees bacteriostatic activity against different bacteria. According to the above properties, P479 has the potential to be applied in phage therapy in the future.

Characterization and genome analysis of Klebsiella phage P509, with lytic activity against clinical carbapenem-resistant Klebsiella pneumoniae of the KL64 capsular type.

The increasing population infected by carbapenem-resistant Klebsiella pneumoniae necessitates the development of alternative therapies. In this study, we isolated, characterized, and sequenced a bacteriophage, P509, which was able to specifically infect and lyse carbapenem-resistant K. pneumoniae of K locus type KL64. A one-step growth curve experiment showed that the latent time period of phage P509 was 5 min, and the burst size was about 85 phage particles/cell. Stability tests confirmed that P509 was stable over a wide range of temperatures (4 to 50 °C) and pH (3 to 11) conditions. Phage P509 was identified as a linear double-stranded DNA phage with a genome of 40,954 bp with 53.2% G + C content, encoding 50 predicted proteins. Genomic and morphological analysis suggested that P509 belonged to the genus Przondovirus, family Autographiviridae, order Caudovirales. Further analysis showed that no virulence-related genes or lysogen-formation gene clusters were detected in the genome, suggesting that P509 is a lytic phage, making it potentially suitable for clinical applications. In vitro, the number of viable cells in three phage-treated groups (MOI = 0.1, 0.01, 0.001) decreased by 3.75 log10 CFU/ml, 3.32 log10 CFU/ml and 3.21 log10 CFU/ml, respectively, after 80 min of incubation, in comparison to that in the untreated group. Based on these characteristics, phage P509 may be a promising candidate for future phage therapy applications.

Combined effects of glycated hemoglobin A1c and blood pressure on carotid artery atherosclerosis in nondiabetic patients.

BACKGROUND: The relationship between HbA(1c), blood pressure, and carotid atherosclerosis in nondiabetic patients is not clear. HYPOTHESIS: HbA(1c) and blood pressure can affect carotid-artery atherosclerosis in nondiabetic patients. METHODS: This retrospective cross-sectional study included 216 patients without diabetes mellitus. A positive carotid ultrasonographic result was defined as intima-media thickness of the common carotid artery ≥ 0.9 mm, or presence of carotid plaque. RESULTS: Compared with patients without carotid atherosclerosis, patients with carotid atherosclerosis had significantly higher levels of HbA(1c) and systolic blood pressure (SBP). Higher levels of HbA(1c) and SBP were found to be associated with increased carotid atherosclerosis. Given similar SBP levels, higher HbA(1c) (>5.6%) was also related to increased carotid atherosclerosis. In multiple logistic regression analysis, HbA(1c) (odds ratio: 4.1, P = 0.009) emerged as the only statistically significant modifiable factor that was associated with carotid atherosclerosis, independent of smoking, body mass index, fasting plasma glucose, 2-hour plasma glucose, SBP, diastolic blood pressure, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol. CONCLUSIONS: Our study shows that a slight increase of HbA(1c) may associate with carotid atherosclerosis in nondiabetic patients. Moreover, the coexistence of an elevated SBP level and a slightly increased HbA(1c) level may have a more significant effect on carotid atherosclerosis.