Streptococcus pneumoniae (S. pneumoniae) is a major pathogen of infectious diseases in children. Surveillance of the distribution of pneumococcus serotypes is important for immunization strategies of pneumococcal polysaccharide conjugate vaccines (PCVs). Areas covered: This article is a systematic review of studies conducted from 2006 to 2016 that document serotypes of S. pneumoniae isolated from children less than 14 years old in the mainland of China. A total of 40 studies were included in this review. Serotypes 19F, 19A, 23F, 14 and 6B were the most common. Serotype prevalence and percentage varied by region and associated strains. The serotype coverage rate of PCV13 was higher than that of PCV10 due to the prevalence of serotype 19A, and there were no significant difference between the coverage rate of PCV13 and PPSV23. Expert commentary: To prevent Chinese children from S. pneumoniae infection, it is necessary for the universal immunization of PCV13 or develop new vaccines that include all the prevalent serotypes in China.
Non-heme iron and α-ketoglutarate-dependent (Fe/αKG) oxygenases catalyze various oxidative biotransformations. Due to their catalytic flexibility and high efficiency, Fe/αKG oxygenases have attracted keen attention for their application as biocatalysts. Here, we report the biochemical and structural characterizations of the unusually promiscuous and catalytically versatile Fe/αKG oxygenase SptF, involved in the biosynthesis of fungal meroterpenoid emervaridones. The in vitro analysis revealed that SptF catalyzes several continuous oxidation reactions, including hydroxylation, desaturation, epoxidation, and skeletal rearrangement. SptF exhibits extremely broad substrate specificity toward various meroterpenoids, and efficiently produced unique cyclopropane-ring-fused 5/3/5/5/6/6 and 5/3/6/6/6 scaffolds from terretonins. Moreover, SptF also hydroxylates steroids, including androsterone, testosterone, and progesterone, with different regiospecificities. Crystallographic and structure-based mutagenesis studies of SptF revealed the molecular basis of the enzyme reactions, and suggested that the malleability of the loop region contributes to the remarkable substrate promiscuity. SptF exhibits great potential as a promising biocatalyst for oxidation reactions.
The spread of carbapenem-resistant Klebsiella pneumoniae (CRKp) has become a significant problem worldwide; however, relevant data in children are limited. We performed a retrospective study to better understand the epidemiology of CRKp bloodstream infections at Beijing Children's Hospital. A total of 164 K. pneumoniae strains were collected from blood cultures between January 2011 and September 2014, of which 52 (31.7%) were CRKp strains. All 52 CRKp strains were multidrug resistant; 46 (88.5%) and 49 (94.2%) isolates were resistant to meropenem and imipenem, respectively. Low rates of resistance to amikacin (5.8%), levofloxacin (7.7%), and ciprofloxacin (15.4%) were observed. All isolates were susceptible to colistin. Among the tested carbapenem resistance genes, the predominant gene was bla, detected in 28 (53.8%) isolates, followed by bla (19, 36.5%) and bla (4, 7.7%). Multilocus sequence typing identified 31 sequence types (STs), the most predominant of which was ST782 (9, 29.0%). All ST782 strains were New Delhi metallo-β-lactamase-1 (NDM-1) producing. Four novel STs (ST2010, ST2011, ST2012, and ST2013) and two novel alleles (phoE243 and tonB324) were also detected. Hematologic disease was the most common underlying disease (73.1%). All children received initial empirical therapy. A total of 59.6% (31/52) patients received inappropriate empirical therapy, and 45.2% (14/31) changed antimicrobial therapy after blood culture results were obtained. The overall mortality rate was 11.5%. In conclusion, we observed a high rate of CRKp isolates collected from blood cultures and the predominance of NDM-1-producing K. pneumoniae among children from 2011 to 2014.
The coverage rates of PCVs were high, and the antibiotic resistance rates were of serious concern among hospitalized children. Universal immunization using PCVs would likely prevent episodes of S. pneumoniae diseases and the spread of antibiotic resistance in Beijing.
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