Facile synthesis of water-soluble silver nanoclusters for the photocatalytic degradation of dyes by multivariate optimization approach.

In this study, silver nanoclusters protected by the natural tripeptide ligand (GSH@Ag NCs) were constructed for photocatalytic dye degradation. The ultrasmall GSH@Ag NCs were found to exhibit a remarkably high degradation capability. Aqueous solutions of the hazardous organic dye Erythrosine B (Ery. B) and Rhodamine B (Rh. B) were subjected to degradation in the presence of Ag NCs under solar light and white-light LED irradiation. The degradation efficiency of GSH@Ag NCs was evaluated using UV-vis spectroscopy, where Erythrosine B showed considerably high degradation of 94.6% compared to Rhodamine B, which was degraded by 85.1%, corresponding to a 20 mg L-1 degradation capacity in 30 min respectively under solar exposure. Moreover, the degradation efficacy for the above-mentioned dyes demonstrated a dwindling trend under white-light LED irradiation, attaining 78.57 and 67.923% degradation under the same experimental conditions. The astoundingly high degradation efficiency of GSH@Ag NCs under solar-light irradiation was due to the high I of 1370 W for solar light versus 0.07 W for LED light, along with the formation of hydroxyl radicals HO˙ on the catalyst surface initiating degradation due to oxidation.

The Co-occurrence of mcr-3 and fosA3 in IncP plasmid in ST131 Escherichia coli: A novel case.

INTRODUCTION: Plasmid-mediated colistin resistance genes, especially mcr-3 combined with the fosfomycin resistance gene fosA3, are a grave health concern. Our study was designed to determine the epidemiological characteristics of the combination of mcr-3 and fosA3 in Anhui province, China. METHODOLOGY: A total of 127 multi-drug-resistant (MDR) E. coli strains were assessed for antibiotic resistance/sensitivity to detect mcr-3 and fosA3 using polymerase chain reaction (PCR) and sequencing. The genes of interest were conjugated using EC600, and replicon and sequence types (STs) were identified by PCR-based replicon typing (PBRT) and multilocus sequence typing (MLST). Cluster similarity and genomic relatedness among the positive isolates were confirmed by Xbal PFGE. RESULTS: The processed E. coli isolates were highly resistant to the tested antibiotics; the prevalence of mcr-3 was 0.78% in the transferable IncP-type plasmid in ST131, whereas fosA3 prevalence was 38.58% among different transferable plasmids, including IncFIIK, IncFII and IncA/C, and in various STs including ST69, ST1193, ST12, ST46, ST57, ST1196, ST38, ST95, ST131, ST7584 and ST10184. Both were successfully transferred to EC600. The Xbal PFGE cluster exposed similarities among the STs. CONCLUSIONS: Our results show that to control the spread of colistin and fosfomycin resistance genes in human pathogens, the ban on colistin must be continued in animal feeding farms not only in China but around the world; additionally, awareness platforms on the use of colistin must be implemented and strict policies in poultry and pig farms must be maintained. Furthermore, fosfomycin misuse by patients and overuse by physicians must be strictly managed to stop the spread of fosfomycin resistance.

Epidemiological Characterization of Colistin and Carbapenem Resistant Enterobacteriaceae in a Tertiary: A Hospital from Anhui Province.

PURPOSE: Antimicrobial resistance, especially carbapenem resistance Enterobacteriaceae and plasmid mediated mobile colistin resistance, is a serious issue worldwide. This study was designed to determine the epidemiological characteristics of plasmid mediated colistin resistance and carbapenem resistant Enterobacteriaceae from tertiary A hospital located in Hefei, China. METHODS: Totally, 158 carbapenems resistant Enterobacteriaceae (CRE) were screened for antibiotic susceptibility, mcr-1, extended spectrum ß-lactamases (ESBLs), metallo-ß-lactamases (MBLs), and fosfomycin resistance genes using PCR and sequencing. The sequence types were identified by multilocus sequence typing (MLST). Plasmid profiles were determined by PCR based replicon typing (PBRT), and the plasmid sizes were confirmed by southern blotting. RESULTS: The isolates showed high MIC50 and MIC90 for all antimicrobials, except tigecycline, meropenem, and colistin. The main Carbapenemase genes were bla KPC-2 (90.5%), bla NDM-1(3.7%), bla OXA-48(5.6%) and fosA3 (14.5%). The bla CTXM-15 found 36.7%, mcr-1 (3.7%) recorded in six isolates. PBRT revealed bla KPC-2 in K. pneumoniae on IncR, IncFII, and IncA/C. bla NDM-1 in E. coli on IncFII, whereas in E. cloacae noticed on IncHI2 plasmid. mcr-1 was recorded among IncFIIK, IncFII, and IncF in E. coli, K. pneumoniae, and E. cloacae. Resistance genes (mcr-1, bla NDM-1, bla KPC-2) harboring plasmids are successfully trans-conjugant to EC-600. A high incidence of ST11 was observed in K. pneumoniae carbapenem resistant isolates. While in E. coli, multiple STs were identified. However, mcr-1 in ST23 was identified for the first time in Anhui Province. Among Enterobacter cloacae, ST270 detected carrying bla NDM-1. Southern-hybridization confirmed the plasmid sizes 35-150kb. CONCLUSION: This study indicates the co-carrying of mcr-1, bla KPC-2, and bla NDM-1 among clinical isolates, the prevalence of different Enterobacteriaceae STs is alarming, especially in E. coli. Holding such a resistance profile is a threat for humans and animals, which may be transferred between the strains through plasmid transfusion. Persistent control actions are immediately necessary to combat this hazard.

Antibiotic resistance in Pakistan: a systematic review of past decade.

BACKGROUND: During the last six decades, extensive use of antibiotics has selected resistant strains, increasing the rate of fatal infectious diseases, and exerting an economic burden on society. This situation is widely accepted as a global problem, yet its degree is not well elucidated in many regions of the world. Up till now, no systemic analysis of Antimicrobial resistance (AMR) in Pakistan has been published. The current study aims to describe the antibiotic-resistance scenario of Pakistan from human samples of the last 10 y, to find the gaps in surveillances and methodology and recommendations for researchers and prescribers founded on these outcomes. METHODS: Original research articles analyzed the pattern of Antibiotic resistance of any World Health Organization (WHO) enlisted priority pathogens in Pakistan (published onward 2009 till March 2020), were collected from PubMed, Google scholar, and PakMedi Net search engines. These articles were selected based on predefined inclusion and exclusion criteria. Data about the study characteristics and antibiotic-resistance for a given bacterium were excluded from literature. Antibiotic resistance to a particular bacterium was calculated as a median resistance with 95% Confidence Interval (CI). RESULTS: Studies published in the last 10 y showed that Urinary Tract Infection (UTI) is the most reported clinical diagnosis (16.1%) in Pakistan. E. coli were reported in 28 (30.11%) studies showing high resistance to antibiotics' first line. Methicillin-resistant Staphylococcus aureus (MRSA) was found in 49% of S. aureus' total reported cases. Phenotypic resistance pattern has mostly been evaluated by Disk Diffusion Method (DDM) (82.8%), taken Clinical Laboratory Standards Institute (CLSI) as a breakpoint reference guideline (in 79.6% studies). Only 28 (30.11%) studies have made molecular identification of the resistance gene. blaTEM (78.94% in Shigella spp) and blaNDM-1 (32.75% in Klebsiella spp) are the prominent reported resistant genes followed by VanA (45.53% in Enterococcus spp), mcr-1 (1.61% in Acinetobacter spp), and blaKPC-2 (31.67% in E. coli). Most of the studies were from Sindh (40.86%), followed by Punjab (35.48%), while Baluchistan's AMR data was not available. CONCLUSION: Outcomes of our study emphasize that most of the pathogens show high resistance to commonly used antibiotics; also, we find gaps in surveillances and breaches in methodological data. Based on these findings, we recommend the regularization of surveillance practice and precise actions to combat the region's AMR.

Structural characterization of the hypothetical protein Lpg2622, a new member of the C1 family peptidases from Legionella pneumophila.

The Legionella pneumophila type II secretion system can promote bacterial growth under a wide variety of conditions and mediates the secretion of more than 25 proteins, including the uncharacterized effector Lpg2622. Here, we determined the crystal structures of apo-Lpg2622 and Lpg2622 in complex with the cysteine protease inhibitor E64. Structural analysis suggests that Lpg2622 belongs to the C1 family peptidases. Interestingly, unlike the other structurally resolved papain-like cysteine proteases, the propeptide of Lpg2622 forms a novel super-secondary structural fold (hairpin-turn-helix) and can be categorized into a new group. In addition, the N-terminal ß-sheet of the Lpg2622 propeptide plays a regulatory role on enzymatic activity. This study enhances our understanding of the classification and regulatory mechanisms of the C1 family peptidases.