scholarly journals DETECTION OF AMINOGLYCOSIDE AND QUINOLONE RESISTANCE GENES AND EVALUATION OF POLYMYXIN B SUSCEPTIBILITY PROFILE IN ACINETOBACTER BAUMANNII CLINICAL ISOLATES IN TEHRAN, IRAN DURING 2015-2016

2018 ◽  
Vol 10 (1) ◽  
pp. e2018044 ◽  
Author(s):  
Mohsen Heidary
Keyword(s):  
Acinetobacter Baumannii ◽  
Resistance Genes ◽  
Antimicrobial Susceptibility ◽  
Polymyxin B ◽  
Quinolone Resistance ◽  
Clinical Isolates ◽  
Diffusion Method ◽  
Clinical Samples ◽  
Antimicrobial Susceptibility Tests ◽  
Susceptibility Tests

ABSTRACTAcinetobacter baumannii is an important opportunistic pathogen, responsible for approximately 10% of all gram-negative nosocomial infection. The main aims of this study were to detect aminoglycoside and quinolone resistance genes among clinical isolates of A. baumannii and determine the antimicrobial susceptibility profiles. Current study was performed from February 2015 to April 2016, at two teaching hospitals. One-hundred A. baumannii isolates were collected from different clinical samples. Antimicrobial susceptibility tests were done by disk diffusion method according to CLSI guidelines. Detection of the qnrA, anrB, qnrS, aac(3)-IIa, and aac(6′)-Ib genes was done by PCR assay. The results of antibiotic susceptibility tests indicated that polymyxin B was the most effective drug against isolates of A. baumannii and the isolates were most resistant to cefepime (97%), ceftriaxone (95%), and amikacin (82%). The aac(3)-IIa, aac(6′)-Ib, and qnrA genes were found in 45%, 50%, and 50% of isolates, respectively. However, qnrB and qnrS genes could not be detected in any A. baumannii isolate.This study showed that there is a high level of resistance genes among clinical isolates of A. baumannii circulating in hospitals in Iran. This high prevalence rate highlights the necessity for establishing rapid diagnostic assays, more antimicrobial susceptibility tests, continuous antibiotic resistance monitoring.Keywords: Acinetobacter baumannii, Aminoglycoside, Quinolone, Iran

scholarly journals Detection of OXA Beta Lactamases Among Clinical Isolates of Acinetobacter baumannii Isolated from Tehran Hospitals, Iran

2019 ◽  
Vol 13 (1) ◽  
pp. 68-72
Author(s):  
Reza Ranjbar ◽  
Shahin Zayeri ◽  
Davoud Afshar ◽  
Shohreh Farshad
Keyword(s):  
Acinetobacter Baumannii ◽  
Early Recognition ◽  
Bacterial Pathogen ◽  
Polymyxin B ◽  
Clinical Isolates ◽  
Hospital Environment ◽  
Diffusion Method ◽  
Disk Diffusion Method ◽  
Molecular Tests ◽  
High Level

Background and Objective:Acinetobacter baumanniiis a non-motile Gram-negative bacterial pathogen with the history of vast resistant to antibiotics. The aim of this study was to determine the possibility of existence of OXAs genes among clinical isolates ofA. baumanniiobtained from Tehran hospitals.Materials and Methods:A total of 101 isolates were identified asA. baumanniiby common biochemical and molecular tests. The susceptibility to different antibiotics was assessed with Kirby-Bauer disk diffusion method. Phenotypic Detection of MBLs was performed with CDT test and PCR assay was also performed for detection ofblaOXA-23-like,blaOXA-24-like,blaOXA-40-like,blaOXA-51-like,blaOXA-58-likeandblaOXA-143-likegenesResults:All isolates ofA. baumanniishowed high-level of resistance to all antibiotics except for Polymyxin B. TheblaOXA-51 likegenes was found in all of the isolates and the prevalence ofblaOXA-143like,blaOXA-23like,blaOXA-40likeandblaOXA-24likewere 56%, 45.45%, 33% and 11.8%, respectively.Conclusion:TheblaOXA-51-likewas the predominant mechanism of resistance to imipenem inA. baumanniiand therefore, early recognition of carbapenem-resistantA. baumanniiisolates is a useful tools to prevent their spreading within the hospital environment.

scholarly journals Variability in carbapenemase activity of intrinsic OxaAb (OXA-51-like) β-lactamase enzymes in Acinetobacter baumannii

2020 ◽  
Author(s):  
Yuiko Takebayashi ◽  
Jacqueline Findlay ◽  
Kate J Heesom ◽  
Philip J Warburton ◽  
Matthew B Avison ◽  
...  
Keyword(s):  
Molecular Evolution ◽  
Acinetobacter Baumannii ◽  
Active Site ◽  
Carbapenem Resistance ◽  
Clinical Isolates ◽  
Resistance Factors ◽  
Resistance Determinants ◽  
Evolution Analysis ◽  
Antimicrobial Susceptibility Tests ◽  
Susceptibility Tests

Abstract Objectives To measure the variability in carbapenem susceptibility conferred by different OxaAb variants, characterize the molecular evolution of oxaAb and elucidate the contribution of OxaAb and other possible carbapenem resistance factors in the clinical isolates using WGS and LC–MS/MS. Methods Antimicrobial susceptibility tests were performed on 10 clinical Acinetobacter baumannii isolates. Carbapenem MICs were evaluated for all oxaAb variants cloned into A. baumannii CIP70.10 and BM4547, with and without their natural promoters. Molecular evolution analysis of the oxaAb variants was performed using FastTree and SplitsTree4. Resistance determinants were studied in the clinical isolates using WGS and LC–MS/MS. Results Only the OxaAb variants with I129L and L167V substitutions, OxaAb(82), OxaAb(83), OxaAb(107) and OxaAb(110) increased carbapenem MICs when expressed in susceptible A. baumannii backgrounds without an upstream IS element. Carbapenem resistance was conferred with the addition of their natural upstream ISAba1 promoter. LC–MS/MS analysis on the original clinical isolates confirmed overexpression of the four I129L and L167V variants. No other differences in expression levels of proteins commonly associated with carbapenem resistance were detected. Conclusions Elevated carbapenem MICs were observed by expression of OxaAb variants carrying clinically prevalent substitutions I129L and L167V. To drive carbapenem resistance, these variants required overexpression by their upstream ISAba1 promoter. This study clearly demonstrates that a combination of IS-driven overexpression of oxaAb and the presence of particular amino acid substitutions in the active site to improve carbapenem capture is key in conferring carbapenem resistance in A. baumannii and other mechanisms are not required.

scholarly journals Molecular epidemiology and antimicrobial resistance features of Acinetobacter baumannii clinical isolates from Pakistan

2020 ◽  
Vol 19 (1) ◽  
Author(s):  
Nabil Karah ◽  
Fizza Khalid ◽  
Sun Nyunt Wai ◽  
Bernt Eric Uhlin ◽  
Irfan Ahmad
Keyword(s):  
Antimicrobial Resistance ◽  
Molecular Epidemiology ◽  
Acinetobacter Baumannii ◽  
Resistance Genes ◽  
Antimicrobial Agents ◽  
Opportunistic Pathogen ◽  
Clinical Isolates ◽  
Diffusion Method ◽  
Agar Disc ◽  
Antimicrobial Resistance Genes

Abstract Background Acinetobacter baumannii is a Gram-negative opportunistic pathogen with a notorious reputation of being resistant to antimicrobial agents. The capability of A. baumannii to persist and disseminate between healthcare settings has raised a major concern worldwide. Methods Our study investigated the antibiotic resistance features and molecular epidemiology of 52 clinical isolates of A. baumannii collected in Pakistan between 2013 and 2015. Antimicrobial susceptibility patterns were determined by the agar disc diffusion method. Comparative sequence analyses of the ampC and blaOXA-51-like alleles were used to assign the isolates into clusters. The whole genomes of 25 representative isolates were sequenced using the MiSeq Desktop Sequencer. Free online applications were used to determine the phylogeny of genomic sequences, retrieve the multilocus sequence types (ST), and detect acquired antimicrobial resistance genes. Results Overall, the isolates were grouped into 7 clusters and 3 sporadic isolates. The largest cluster, Ab-Pak-cluster-1 (blaOXA-66 and ISAba1-ampC-19) included 24 isolates, belonged to ST2 and International clone (IC) II, and was distributed between two geographical far-off cities, Lahore and Peshawar. Ab-Pak-clusters-2 (blaOXA-66, ISAba1-ampC-2), and -3 (blaOXA-66, ISAba1-ampC-20) and the individual isolate Ab-Pak-Lah-01 (ISAba1-blaOXA-66, ISAba1-ampC-2) were also assigned to ST2 and IC II. On the other hand, Ab-Pak-clusters-4 (blaOXA-69, ampC-1), -5 (blaOXA-69, ISAba1-ampC-78), and -6A (blaOXA-371, ISAba1-ampC-3) belonged to ST1, while Ab-Pak-cluster-6B (blaOXA-371, ISAba1-ampC-8) belonged to ST1106, with both ST1 and ST1106 being members of IC I. Five isolates belonged to Ab-Pak-cluster-7 (blaOXA-65, ampC-43). This cluster corresponded to ST158, showed a well-delineated position on the genomic phylogenetic tree, and was equipped with several antimicrobial resistance genes including blaOXA-23 and blaGES-11. Conclusions Our study detected the occurrence of 7 clusters of A. baumannii in Pakistan. Altogether, 6/7 of the clusters and 45/52 (86.5%) of the isolates belonged to IC I (n = 9) or II (n = 36), making Pakistan no exception to the global domination of these two clones. The onset of ST158 in Pakistan marked a geographical dispersal of this clone beyond the Middle East and brought up the need for a detailed characterization.

scholarly journals 1593. Analysis of Hospital Antimicrobial Susceptibility Test Results for Patterns of Antibiotic Resistance

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S581-S581
Author(s):  
Andrew Beckley ◽  
Erik S Wright
Keyword(s):  
Antibiotic Resistance ◽  
Antimicrobial Susceptibility ◽  
Medical Center ◽  
Clinical Samples ◽  
University Of Pittsburgh ◽  
Collateral Sensitivity ◽  
Treatment Techniques ◽  
Antimicrobial Susceptibility Tests ◽  
Susceptibility Tests ◽  
Organism Identification

Abstract Background Antimicrobial susceptibility tests (ASTs) are routinely performed on pathogens isolated from clinical samples. ASTs are used by clinicians to select the most appropriate treatment for antibiotic-resistant microorganisms. In aggregate, ASTs offer insight into the rise and spread of antibiotic resistance across hospitals. Here, we used ASTs to identify patterns of antibiotic resistance across drugs and microorganisms. Methods We conducted a retrospective analysis of 364,813 AST results from the University of Pittsburgh Medical Center from 2015 to 2018. Data regarding infection site, hospital laboratory testing, organism identification, and antibiotic susceptibilities were extracted from the laboratory information system and anonymized prior to use. The pathogens studied included Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii, Staphylococcus aureus, Proteus mirabilis, and Enterococcus faecalis. Results We identified 21 antibiotic-pathogen combinations where resistance was found in less than 1% of AST results. Concordant susceptibility results of levofloxacin and ciprofloxacin occurred the most frequently among antibiotic pairs. Additionally, concordant susceptibility results were more common within antibiotics belonging to the same antibiotic class than between classes. P. aeruginosa had the highest rate of overall concordant results with concordance occurring within all -lactam classes. In contrast, K. pneumoniae and P. mirabilis showed the least concordance, suggesting that their resistance profiles are less predictable. Notably, we did not identify any pairs of antibiotics that strongly exhibited discordant susceptibility results regardless of the microorganism. Conclusion Using routinely collected clinical microbiological data, we were able to characterize pathogen-antibiotic combinations where resistance is rarely seen. Additionally, we identified pairs of antibiotics that frequently exhibited concordance susceptibilities both within and between classes. Lastly, we were unable to find evidence of discordant susceptibility results, indicating that more clinical research is needed to determine the efficacy of collateral sensitivity treatment techniques. Disclosures All authors: No reported disclosures.

scholarly journals Prevalence of β-lactamase-encoding genes and molecular typing of Acinetobacter baumannii isolates carrying carbapenemase OXA-24 in children

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Neda Yousefi Nojookambari ◽  
Mehrzad Sadredinamin ◽  
Razieh Dehbanipour ◽  
Zohreh Ghalavand ◽  
Gita Eslami ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Genetic Relatedness ◽  
Medical Center ◽  
Resistance Rate ◽  
Diffusion Method ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Antimicrobial Susceptibility Tests ◽  
Susceptibility Tests ◽  
Encoding Genes

Abstract Background β-Lactam antibiotics have been broadly used for the treatment of Acinetobacter baumannii infections, resulting in development of β-lactam inactivating β-lactamases. Here, we described antibiotic resistance rate, prevalence of β-lactamase-encoding genes, and clonal relationships of A. baumannii strains isolated from children referred to Children’s Medical Center in Tehran, Iran, during 2019–2020. Methods A total of 60 non-replicate A. baumannii isolates were recovered from clinical specimens of pediatric patients. Antibiotic susceptibility testing was done by the disc diffusion method. Colistin susceptibility of isolates was performed by the broth microdilution method. β-lactamase-encoding genes were characterized by PCR. The presence of ISAba1 element upstream of the several oxacillinase genes was also checked. Genetic relatedness of isolates was determined by using random amplification of polymorphic DNA (RAPD) typing. Results The antimicrobial susceptibility tests showed that 83.3% of A. baumannii isolates were MDR, and 40% XDR. Both MDR and XDR A. baumannii isolates were susceptible to colistin. The frequency of blaOXA-51-like, blaOXA-23-like, blaTEM, blaOXA-24-like, blaPER, blaSHV, blaCTX-M, blaOXA-58-like, and blaIMP was 100, 93.33, 60, 36.67, 28.33, 8.33, 5, 3.33, and 1.67%, respectively. Coexistence of ISAba1/blaOXA-23-like and ISAba1/blaOXA-51-like was observed in 65% and 85% of isolates, respectively. RAPD analysis revealed 4 common types and 2 single types of A. baumannii isolates. Conclusions The multiple clones harboring blaOXA-23-like, ISAba1-blaOXA-51-like, and ISAba1-blaOXA-23-like were responsible for the spread of A. baumannii isolates in our clinical wards. Dissemination of the well-established clones is worrisome and would become therapeutic challenges due to the possible transferring genetic elements associated with resistance.

scholarly journals Identification of Acinetobacter baumannii and detection of ß - lactam antibiotic resistance genes in clinical samples by multiplex PCR

2020 ◽  
Author(s):  
Trinh Phan-Canh ◽  
Thao Le-Thi-Thanh ◽  
Thuy Ngo-Thi-Bich ◽  
Thanh Nguyen-Thi-Thanh ◽  
Linh Ho-Le-Truc ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Acinetobacter Baumannii ◽  
Multiplex Pcr ◽  
Resistance Genes ◽  
Antibiotic Resistance Genes ◽  
Clinical Isolates ◽  
Clinical Samples ◽  
List Type ◽  
Sensitivity Testing ◽  
Lactam Antibiotic

AbstractAcinetobacter baumannii is the leading cause of hospital-acquired infection in Vietnam. Of note, antibiotic resistance genes are significantly popular in clinical isolates of A. baumannii. Therefore, rapid identification of A. baumannii and determination of antibiotic resistance genes will help to make effective clinical decisions related to antibiotic use. This paper proposes a multiplex PCR to identify Acinetobacter baumannii and detect their ß-lactam antibiotic resistance genes in clinical isolates. Multiplex PCR was applied to amplified recA gene and region ITS 16S - 23S rDNA for Rapid detection of A. baumannii. The two antibiotic resistance genes - blaOXA-51-like, ampC gene - were detected by multiplex PCR and three genes coding Extended-spectrum beta-lactamases - blaCTX-M, blaTEM, blaSHV genes - were subjected to PCR. 49 bacteria strains were subjected to colony PCR. The result showed that 46 strains were A. baumannii and 3 strains belonged to the genus Acinetobacter. The multiplex PCR showed that all of 46 A. baumannii containing the blaOXA-51-like gene and the AmpC gene; 34 strains possess the gene blaTEM and none of them has blaCTX-M and blaSHV genes. The results of the multiplex PCR are the same as those of the in vitro antibiotic sensitivity testing of A. baumannii. However, applying the multiplex PCR directly from the bacteria colony, we can proceed simultaneously with the bacterial identification and the antibiotic resistance gene detection.Highlights100% of isolates of A. baumannii contains the blaOXA-51-like gene and the AmpC gene.34/46 isolates possess the gene blaTEM, however, do not contain blaCTX-M and blaSHV genes.Combined disc test with cefotaxime/clavulanic acid/boronic acid is an excellent method to analyse ESBL phenotype.

scholarly journals Five years prospective survey of antibiotic resistance in Bacteroides and Parabacteroides isolated from inpatients of clinical hospital in Warsaw, Poland

2020 ◽  
pp. 13-19
Keyword(s):  
Clavulanic Acid ◽  
Antimicrobial Susceptibility ◽  
Bacterial Infections ◽  
Anaerobic Bacteria ◽  
Empirical Therapy ◽  
Drug Susceptibility ◽  
Clinical Isolates ◽  
Patient Treatment ◽  
Antimicrobial Susceptibility Tests ◽  
Susceptibility Tests

Objectives: Diagnostics of anaerobic bacterial infections and determination of drug susceptibility are technically difficult and time-consuming; therefore, the number of studies on Anaerobic Gram-negative bacilli is significantly limited, especially in Europe. The aim of the study was to analyze the antibiotic susceptibility of clinically important anaerobic bacteria Bacteroides spp. and Parabacteroides distasonis. Strains were isolated from infections of patients hospitalized at one Polish hospital as a result of routine microbiological diagnostics. Material and methods: Clinical isolates were identified with MALDI-TOF MS. Antimicrobial susceptibility of 276 strains was carried out by E-test gradient strip to commonly used antibiotics i.e. benzylpenicillin, amoxicillin with clavulanic acid, imipenem, clindamycin and metronidazole. MIC values were determined. The interpretation of antimicrobial susceptibility tests were conducted in accordance with The European Committee on Antimicrobial Susceptibility Testing (EUCAST) recommendations. Results: Susceptibility tests of all isolates yielded the following rates of resistance to the evaluated β-lactam antibiotics: benzylpenicillin (96%), amoxicillin/clavulanic acid (7.6%), imipenem (2.1%). In presented study 38.8% of clindamycin-resistant strains were isolated, among them 18.3% of B. fragilis and 53.85% P. distasonis. All strain were susceptible to metronidazole. Conclusions: Obtained results and analysis of the results of other researchers convinces us that it is necessary to routinely or at least periodically monitor drug susceptibility of clinical isolates of anaerobic bacteria and use targeted therapy based on the result of the antibiogram. Although high percentage of the tested Bacteroides and Parabacteroides strains remained susceptible to metronidazole and β-lactam antibiotics the use of clindamycin in empirical therapy may not be efficacious. Antibiogram results should be consult with the staff responsible for patient treatment and hospital antibiotic policies.

scholarly journals Antimicrobial Resistance Profile Among Major Bacterial Pathogens in Southern Babil, Iraq

2020 ◽  
Vol 27 (3) ◽  
pp. E202036
Author(s):  
Falah Hasan AL-Khikani
Keyword(s):  
Antimicrobial Susceptibility ◽  
Bacterial Species ◽  
High Rate ◽  
Diffusion Method ◽  
Bacterial Isolates ◽  
Appropriate Treatment ◽  
Microbiological Methods ◽  
Antimicrobial Susceptibility Tests ◽  
Male Patients ◽  
Susceptibility Tests

Background: At present, drug-resistant pathogens are considered one of the major increasing causes of morbidity and mortality around the world. The data on microorganisms' resistance assist define the best available treatment for patients. Therefore, this study aimed to screen the antimicrobial-resistant profile of different drugs in major clinical pathogens of urine, ear and wound infections. Methods: This study was conducted in Al-Shomali General Hospital, Southern Babil, Iraq from October 2019 to May 2020. Totally 67 clinical specimens obtained from the wound, urine, and ear discharge collected from hospitalized patients as well as 30 healthy individuals participate in this study. Then, the standard microbiological methods carried outperformed to the isolated and identified bacterial species. Antimicrobial susceptibility tests were performed using different antimicrobial discs by applying the Kirby–Bauer disc diffusion method. Results: Totally, 67 bacterial isolates were obtained from 44 (66%) female and 23 (34%) male patients. Staphylococcus aureus and E. coli were the most common predominant organisms. All isolates were showed a high rate of resistance to evaluated cephalosporins 100% and 87% to cefotaxime and ceftriaxone respectively, while very low resistance recorded in Aminoglycosides 22% and 12% to Gentamicin and amikacin, respectively. Conclusion: These results suggest a constant screening for the detection of antibiotic resistance, as well as developing antimicrobial stewardship programs in Babil, Iraq. Moreover, these bacterial isolates have shown multidrug resistance, mainly to commonly administered drugs that could cause therapy ineffective. Therefore, in clinical use, appropriate treatment should be chosen based on the results obtained from antimicrobial susceptibility tests.

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