Detection of Drug Resistant Genes among A. baumannii by In silico PCR Method

Background: Acinetobacter baumannii is a gram-negative bacterium classified as an opportunistic pathogen in humans by the World Health Organization. Different genetic determinants contribute to multidrug resistance, and transform it as a nosocomial pathogen. Aim: Using in-silico PCR, this analysis aims to characterize the 13 distinct drug resistant genes found in 19 virulent A.baumannii strains. Materials & Methods: There were 11 A.baumannii multidrug resistance genes chosen. In-silico PCR amplification was performed using forward and reverse primers from the 11 genes described in previous research. The amplicon bands were detected in 19 strains of A.baumannii that were set as default on the server. Results: Among the 13 multidrug resistance genes studied, tet A, tet B, Sul 1, Sul 2, DfrA1, ISAba-1 and ISAba-125 were detected among the 19 virulent strains of ​A.baumannii​. Conclusion: The findings of the study documents the frequency of tet A, tet B, Sul 1, Sul 2, DfrA1, ISAba-1 and ISAba-125 like from the selected strains of A. baumannii. However, more experimental validation is needed in order to conduct routine surveillance on drug-resistant A. baumannii strains in hospital settings.

Metagenomic Assembly Reveals the Fate of the Core Antibiotic Resistome, its Hosts and Mobility in Animal Manure and After Compost

Background Antibiotics and antibiotic resistance genes (ARGs) used in intensive animal husbandry threaten human health worldwide; however, the core resistome, mobility of ARGs, and the composition of ARG hosts in animal manure and the following composts remain unclear. In the present study, metagenomic assembly was used to comprehensively decipher the core resistome and its potential mobility and hosts in animal manure and compost. Results In total, 201 ARGs were shared among different animal (layer, broiler, swine, beef cow, and dairy cow) manures and accounted for 86–99% of total relative abundance of ARGs, which mainly comprised multidrug, macrolide-lincosamide-streptogramin (M-L-S), tetracycline, beta-lactam, aminoglycoside, and sulfonamide resistance genes. Moreover, efficient composting reduced the total relative abundance of ARGs in manure from 0.938 to 0.405 copies per 16S rRNA gene; however, it did not have any remarkable effect on the multidrug, sulfonamide, and trimethoprim resistance genes. Procrustes analysis indicated that composting can reduce antibiotic residues and decrease the correlation between antibiotics and resistance genes. Furthermore, the ARG hosts included Proteobacteria (50.08%), Firmicutes (37.77%), Bacteroidetes (6.49%), and Actinobacteria (5.24%). In manure, aminoglycoside resistance genes were majorly found in Enterococcus, Streptococcus, and Enterobacter; tetracycline resistance genes (TRGs) were found in Pseudomonas, Lactobacillus, and Streptococcus; and multidrug resistance genes were mainly found in Escherichia coli. In our samples, ARGs were more prevalent in plasmids than in chromosomes. The broad host range and diverse mobile genetic elements may be two key factors for ARGs, such as sul1 and aadA, which could survive during composting. The multidrug resistance genes represented the dominant ARGs in pathogenic antibiotic-resistant bacteria (PARB) in manure, and composting could effectively control PARB. Conclusions Our experiments revealed the core resistome in animal manure, classified and relative quantified the ARG hosts, and assessed the mobility of ARGs. Composting can mitigate ARGs in animal manure by altering the bacterial hosts; however, some ARGs can escape from the removal with the survivor heat-tolerant hosts or transfer to these hosts. These findings will help optimize composting strategies for the effective treatment of ARGs and their hosts in farms.

Antimicrobial Resistance Genes in ESBL-Producing Escherichia coli Isolates from Animals in Greece

The prevalence of multidrug resistant, extended spectrum β-lactamase (ESBL)-producing Enterobacteriaceae is increasing worldwide. The present study aimed to provide an overview of the multidrug resistance phenotype and genotype of ESBL-producing Escherichia coli (E. coli) isolates of livestock and wild bird origin in Greece. Nineteen phenotypically confirmed ESBL-producing E. coli strains isolated from fecal samples of cattle (n = 7), pigs (n = 11) and a Eurasian magpie that presented resistance to at least one class of non β-lactam antibiotics, were selected and genotypically characterized. A DNA-microarray based assay was used, which allows the detection of various genes associated with antimicrobial resistance. All isolates harbored blaCTX-M-1/15, while blaTEM was co-detected in 13 of them. The AmpC gene blaMIR was additionally detected in one strain. Resistance genes were also reported for aminoglycosides in all 19 isolates, for quinolones in 6, for sulfonamides in 17, for trimethoprim in 14, and for macrolides in 8. The intI1 and/or tnpISEcp1 genes, associated with mobile genetic elements, were identified in all but two isolates. This report describes the first detection of multidrug resistance genes among ESBL-producing E. coli strains retrieved from feces of cattle, pigs, and a wild bird in Greece, underlining their dissemination in diverse ecosystems and emphasizing the need for a One-Health approach when addressing the issue of antimicrobial resistance.