ABSTRACT
ABSTRACT Polymyxin antibiotics are disfavored owing to their potential clinical toxicity, especially nephrotoxicity. However, the dry antibiotic development pipeline, together with the increasing global prevalence of infections caused by multidrug-resistant (MDR) gram-negative bacteria, have renewed clinical interest in these polypeptide antibiotics. This review highlights the current information regarding the mechanisms of resistance to polymyxins and their molecular epidemiology. Knowledge of the resistance mechanisms and epidemiology of these pathogens is critical for the development of novel antibacterial agents and rapid treatment choices.
ABSTRACT
Drug-resistant bacteria have become a serious threat to human health. Polymyxin has shown strong bactericidal activity to some Gram-negative and Gram-positive bacteria that are resistant to antibiotics， and has become a last-resort treatment option against a variety of multi-drug resistant bacteria. However， due to the abuse of polymyxin in animal breeding， the drug resistance rate of polymyxin in human population has significantly increased. In order to further understand the mechanism of polymyxin resistance， and to take measures to reduce the incidence of polymyxin resistance in the population， this paper reviewed the progress in research of the antibacterial mechanism of polymyxin， the prevalence of polymyxin resistance in the population， the mechanism of polymyxin resistance， and its transmission mode.
ABSTRACT
Drug-resistant bacteria have become a serious threat to human health. Polymyxin has shown strong bactericidal activity to some Gram-negative and Gram-positive bacteria that are resistant to antibiotics， and has become a last-resort treatment option against a variety of multi-drug resistant bacteria. However， due to the abuse of polymyxin in animal breeding， the drug resistance rate of polymyxin in human population has significantly increased. In order to further understand the mechanism of polymyxin resistance， and to take measures to reduce the incidence of polymyxin resistance in the population， this paper reviewed the progress in research of the antibacterial mechanism of polymyxin， the prevalence of polymyxin resistance in the population， the mechanism of polymyxin resistance， and its transmission mode.
ABSTRACT
Abstract INTRODUCTION: Essential oils can serve as novel sources of antibiotics for multidrug-resistant bacteria. METHODS: The multidrug-resistance profile of a Klebsiella aerogenes strain was assessed by PCR and sequencing. The antibacterial activity of Cinnamomum cassia essential oil (CCeo) against K. aerogenes was assessed by broth microdilution and time-kill methods. RESULTS: K. aerogenes showed high antibiotic resistance. The genes bla KPC-2, ampC, bla CTX-M-15, bla OXA-1, and bla TEM were present. CCeo exhibited an inhibitory effect with a minimum inhibitory concentration of 17.57 μg/mL. CONCLUSIONS: The antibacterial activity of CCeo makes it a potential candidate for treating carbapenem- and polymyxin-resistant K. aerogenes strains.
Subject(s)
Humans , Klebsiella Infections/drug therapy , Enterobacter aerogenes , Cinnamomum aromaticum , Anti-Bacterial Agents/therapeutic use , beta-Lactamases , Oils, Volatile , Carbapenems , Polymyxins , Klebsiella pneumoniaeABSTRACT
BACKGROUND The multidrug resistance (MDR) phenotype is frequently observed in Acinetobacter baumannii, the most clinically relevant pathogenic species of its genus; recently, other species belonging to the A. calcoaceticus-A. baumannii complex have emerged as important MDR nosocomial pathogens. OBJECTIVES The present study aimed to verify the occurrence of metallo-β-lactamase genes among distinct Acinetobacter species in a hospital located in the Brazilian Amazon Region. METHODS Antimicrobial susceptibility profiles were determined by broth microdilution. The genetic relationships among these isolates were assessed by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Pyrosequencing reads of plasmids carrying the bla NDM-1 gene were generated using the Ion Torrent™ platform sequencing. FINDINGS A total of six isolates carried bla NDM-1: A. baumannii (n = 2), A. nosocomialis (n = 3), and A. pittii (n = 1); three carried bla IMP-1: A. baumannii, A. nosocomialis, and A. bereziniae. Resistance to colistin was observed for an NDM-1-producing A. nosocomialis isolate. Diverse PFGE patterns and sequence types were found among A. nosocomialis and A. baumannii isolates. The bla NDM-1 sequence was inserted in a Tn125 transposon, while the bla IMP-1 was found as a gene cassette of the class 1 integron In86. MAIN CONCLUSIONS To the best of our knowledge, this is the first report describing the dissemination of bla NDM-1 among distinct Acinetobacter species recovered from the same hospital in South America.
Subject(s)
Humans , Organometallic Compounds , Acinetobacter/isolation & purification , Acinetobacter/genetics , beta-Lactamases , Drug Resistance, Microbial/drug effects , Cross Infection/transmission , Intensive Care UnitsABSTRACT
OBJECTIVE: We describe an IncX4 pHC891/16mcr plasmid carrying mcr-1 in a colistin-resistant and carbapenem-susceptible E. coli isolate (HC891/16), ST156, which caused a blood infection in a Brazilian patient with gallbladder adenocarcinoma. METHODS: Strain HC891/16 was subjected to whole genome sequencing using the MiSeq Platform (Illumina, Inc., USA). Assembly was performed using Mira and ABACAS. RESULTS: The isolates showed resistance only to ciprofloxacin, ampicillin and cefoxitin, and whole-genome sequencing revealed the presence of aac(6')Ib-cr and blaTEM1. CONCLUSION: Our findings warn of the possible silent dissemination of colistin resistance by carbapenem-susceptible mcr-1 producers, as colistin susceptibility is commonly tested only among carbapenem-resistant isolates.
Subject(s)
Humans , Female , Aged , Carbapenems/pharmacology , Bacteremia/drug therapy , Colistin/pharmacology , Escherichia coli Proteins/drug effects , Escherichia coli/drug effects , Anti-Bacterial Agents/pharmacology , Plasmids/drug effects , Brazil , Microbial Sensitivity Tests , Escherichia coli Proteins/isolation & purification , Escherichia coli Proteins/genetics , Drug Resistance, Multiple, Bacterial , Escherichia coli/isolation & purification , Escherichia coli/genetics , Escherichia coli Infections/drug therapyABSTRACT
This study describes a carbapenem-resistant Klebsiella pneumoniae (CRKP) outbreak that occurred from October 2008-December 2010. Polymerase chain reaction assays were performed to detect the blaKPC gene and molecular typing was performed using pulsed-field gel electrophoresis (PFGE). There were 33 CRKP infections; PFGE revealed five genotypes: genotype A in five (15%), B in 18 (55%), C in eight (24%) and two unique profiles. Genotype B was disseminated in all hospital units and belonged to the same clone identified in 11 different hospitals in the state of São Paulo. Sixteen (48%) patients died. Seven isolates (21%) were resistant to polymyxin B and 45% were resistant to tigecycline and amikacin.