The removal of tetracycline with biogenic CeO2 nanoparticles in combination with US/PMS process from aqueous solutions: Kinetics and mechanism

Antibiotics have received great attention because of their abuse and potential hazards to the human health and environment. In the current work, peroxymonosulfate (PMS) was added to a cerium oxide (CeO2)/ultrasonic (US) system for tetracycline (TC) degradation. CeO2 nanoparticles (NPs) were synthesized by a simple and cost-effective method using Stevia rebaudiana leaf extract and cerium nitrate as precursors. The as-synthesized CeO2 NPs were characterized by X-ray diffraction, field emission scanning electron microscopy, and Fourier-transform infrared spectroscopy analysis. The effects of catalyst dosage, PMS concentration, US power, initial antibiotic concentration, and pH on TC removal were investigated. The results confirmed the formation of CeO2 NPs with a fluorite structure, spherical shape, and average particle size of 29 nm. The removal efficiency of TC was 92.6 in the optimum oxidation conditions (TC ¼ 15 mg/L, PMS ¼ 50 mM, CeO2 ¼ 0.6 g/L, pH ¼ 6, and US ¼ 70 W) and followed the zero-order kinetics. Experiment scavenger demonstrated both sulfate and hydroxyl radicals (SO4�-�OH) were responsible for degrading antibiotics. Biogenic CeO2 NPs and ultrasound waves-activated PMS is a promising technology for water pollution caused by contaminants such as pharmaceuticals. © 2021 The Authors Water Science & Technology

ISPpu22, a novel insertion sequence in the oprD porin gene of a carbapenem-resistant Pseudomonas aeruginosa isolate from a burn patient in Tehran, Iran

BACKGROUND AND OBJECTIVES: The oprD mutation and AmpC overproduction are the main mechanisms of intrinsic resistance to carbapenems such as imipenem and meropenem in Pseudomonas aeruginosa. MATERIALS AND METHODS: In this study, we investigated intrinsic resistance to carbapenems including mutation of oprD and AmpC overproduction in a carbapenem-resistant P. aeruginosa isolated from a burn patient by phenotypic and molecular methods. RESULTS: In our study, the carbapenem-resistant P. aeruginosa isolate was resistant to imipenem, meropenem, cefepime, gentamicin, ceftriaxone, carbenicillin, aztreonam and ciprofloxacin but was susceptible to ceftazidime and polymyxin B. The minimum inhibitory concentrations (MICs) against imipenem, meropenem and ceftazidime were 64 μg/ml, 16 μg/ml and 2μg/ml, respectively. The isolate was ESBLs and AmpC overproducer. No carbapenemase activity was detected by Modified Hodge test (MHT). This isolate was carrying only bla OXA-10 . PCR amplification and sequencing of oprD performed on isolate resulted in PCR product of 2647bp. Sequence analysis of the 2647bp product revealed insertion of a sequence of 1232 bp at position 8 in coding region of oprD. CONCLUSION: According to the results of this study, oprD mutation and AmpC overproduction can cause the main mechanism of resistance of P. aeruginosa to carbapenems

In vitro reducing effect of cloxacillin on minimum inhibitory concentrations to imipenem, meropenem, ceftazidime, and cefepime in carbapenem-resistant pseudomonas aeruginosa isolates

Today, resistance to antibacterial agents is the most important problem facing public health. Pseudomonas aeruginosa is a common gram-negative bacterium and an important cause of nosocomial infections. Resistance to many antibiotics in strains of P. aeruginosa isolated from hospital settings such as cephalosporins and carbapenems have been recently reported. Therefore, the introduction of a new strategy to treat the infection of these organisms will be beneficial. In this study we determined the ability of cloxacillin to reduce Minimum Inhibitory Concentrations (MICs) of carbapenem-resistant P. aeruginosa to imipenem (IMI), meropenem (MEM), ceftazidime (CAZ), and cefepime (FEP). From 2015 to 2017, 61 non-duplicates of carbapenem-resistant P. aeruginosa were collected from clinical samples of hospitalized patients in Kerman, Iran. The MICs of the isolates to IMI, MEM, CAZ, and FEP with/without cloxacillin were determined by microbroth dilution method. The level of MIC of isolates to carbapenems (IMI and MEM) and cephalosporins (CAZ and FEP) ranged from 1-256 μg/mL and 4-1024 μg/mL alone and from 1-32 μg/mL and 1-512 μg/mL in combination with cloxacillin, respectively. The MIC showed a significant difference reduction after the addition of cloxacillin (P � 0.05). Our results showed in vitro potentially of cloxacillin in reduction of MIC to IMI, MEM, CAZ, and FEP in multi-drug resistant P. aeruginosa, therefore combination of these antibiotics with cloxacillin could be beneficial for treatment of infections caused by multi-drug resistant P. aeruginosa. © 2020, Yale Journal of Biology and Medicine Inc. All rights reserved

Endemic dissemination of different sequence types of carbapenem-resistant Klebsiella pneumoniae strains harboring blaNDM and 16S rRNA methylase genes in Kerman hospitals, Iran, from 2015 to 2017

Somayeh Kiaei,1,2 Mohammad Moradi,2 Hossein Hosseini-Nave,2 Mahsa Ziasistani,3 Davood Kalantar-Neyestanaki2 1Department of Microbiology and Virology, Student Research Committee, School of Medicine, Kerman University of Medical Sciences, Kerman, Iran; 2Department of Microbiology and Virology, School of Medicine, Kerman University of Medical Sciences, Kerman, Iran; 3Pathology and Stem Cell Research Center, School of Medicine, Kerman University of Medical Sciences, Kerman, Iran Introduction: The emergence and spread of Klebsiella pneumoniae strains resistant to multiple antimicrobial agents are considered as a serious challenge for nosocomial infections. Materials and methods: In this study, 175 nonrepetitive clinical isolates of K. pneumoniae were collected from hospitalized patients in Kerman, Iran. Extended-spectrum β-lactamases (ESBLs), AmpC, and carbapenemase-producing isolates were recognized by phenotypic methods. The resistance genes including efflux pumps oqxA/oqxB, 16S rRNA methylase, ESBL, AmpC, and carbapenemase were detected by PCR-sequencing method. Molecular typing was performed by enterobacterial repetitive intergenic consensus-PCR and multilocus sequence typing methods among blaNDM-positive isolates. Results: Thirty-seven (21.14%) isolates along with sequence types (STs): ST43, ST268, ST340, ST392, ST147, and ST16 were harbored blaNDM. ST43 in 2015 and ST268 during 2016–2017 were the most frequent STs among New Delhi metallo-beta-lactamase (NDM)-positive isolates. We found the distribution of some isolates with blaNDM, blaCTX-M, blaSHV, blaOXA, blaTEM, blaCMY, rmtC, and oqxA/oqxB. Enterobacterial repetitive intergenic consensus-PCR represented seven clusters (A–G) plus four singletons among NDM-positive isolates. This study provides the first report of blaNDM-1-positve K. pneumoniae along with ST268 as well as the spread of nosocomial infections with six different STs harboring blaNDM-1 and other resistance genes in hospital settings especially neonatal intensive care unit. Conclusion: The dissemination of various clones of NDM-producing K. pneumoniae can contribute to increase the rate of their spread in health care settings. Therefore, molecular typing and detection of resistance genes have an important role in preventing and controlling infection by limiting the dissemination of multidrug-resistant isolates. Keywords: blaNDM, 16S rRNA methylase, MLST, ERIC-PC

Determination of extended spectrum beta-lactamases, metallo-beta-lactamases and AmpC-beta-lactamases among carbapenem resistant Pseudomonas aeruginosa isolated from burn patients

Background: Pseudomonas aeruginosa is an important cause of morbidity and mortality in patients with burns. Method: A total of 214 nonduplicated burn wound isolates of P. aeruginosa were recovered from burn patients. Identification of carbapenem resistant isolates and their antimicrobial susceptibility pattern was carried out using the phenotypic methods. The presence of genes encoding extended spectrum beta-lactamases (ESBLs) and metallo-beta-lactamases (MBLs) enzymes were determined by PCR. The genetic relationships between carbapenem resistant isolates were determined by Random Amplified Polymorphic DNA (RAPD)-PCR. Results: Of 214 investigated P. aeruginosa isolates, 100 (46.7) were carbapenem resistant. All carbapenem resistant P. aeruginosa were resistant to imipenem, meropenem, ertapenem, carbenicillin, aztreonam, gentamicin and ciprofloxacin but susceptible to polymyxin B. Among 100 carbapenem resistant P. aeruginosa isolates, 3, 65 and 52 were identified as ESBLs, carbapenemase and AmpC overproduction positive isolates respectively. The most prevalent ESBLs and MBLs genes included bla(OXA-10) (97), bla(TEM) (61), bla(VIM) (55), bla(PER) (13), bla(IMP) (3) and bla(AIM) (1). RAPD analysis yielded 13 distinct profiles among 92 isolates. A dominant RAPD type was designated as A that consisting of 80 isolates. Conclusion: This is the first report of Adelaide IMipenmase (AIM) MBLs producing P. aeruginosa from Iran and also of the high prevalence of AmpC overproduction isolates. According to the results of current study, P. aeruginosa isolates producing OXA-10, TEM, VIM, PER and IMP beta-lactamases are frequent and the population structures of these isolates are highly similar. (C) 2014 Elsevier Ltd and ISBI. All rights reserved