scholarly journals Susceptibility to antibiotic combinations of Klebsiella pneumoniae and Acinetobacter baumannii strains isolated from COVID-19 patients

2021 ◽  
Vol 18 (4) ◽  
pp. 33-40
Author(s):  
D. V. Tapalski ◽  
E. V. Karpova
Keyword(s):  
Klebsiella Pneumoniae ◽  
Bactericidal Activity ◽  
Antibacterial Effect ◽  
Bactericidal Effect ◽  
Bacteriostatic Activity ◽  
Broth Microdilution ◽  
Colistin Resistance ◽  
Microdilution Method ◽  
Carbapenem Resistant ◽  
Broth Microdilution Method

Objective. To assess the susceptibility of K.pneumoniae and A.baumanii strains isolated from hospitalized COVID-19 patients to antibiotics and their combinations.Materials and methods. The minimum inhibitory concentrations (MICs) of meropenem and colistin were determined for 47 A.baumannii and 51K.pneumoniaestrains isolated from the hospitalized COVID-19 patients by the broth microdilution method. The susceptibility to 11 antibiotic combinations was assessed using the method of multiple combination bactericidal testing.Results. Colistin resistance was detected in 31.9 % of A.baumannii strains (MIC50 — 0.5 mg/l, MIC90 — 16 mg/l) and in 80.4 % of K.pneumoniaestrains (MIC50 — 16 mg/l, MIC90 — 256 mg/l). It has been shown that double antibiotic combinations with the inclusion of colistin exhibit bactericidal or bacteriostatic activity against 76.6–87.2 % of A.baumannii strains. Combinations with the addition of meropenem, colistin and macrolides exhibited bactericidal activity against 78.4–80.4 % of K.pneumoniae strains. Combinations of two carbapenems were not active, the combination of meropenem-colistin had a bactericidal effect only in 13.7 % of K.pneumoniae strains.Conclusion. Widespread colistin resistance was found in carbapenem-resistant K.pneumoniae and A.baumannii strains isolated from the hospitalized COVID-19 patients. The combinations of antibiotics that have a synergistic antibacterial effect in their pharmacokinetic/pharmacodynamic concentrations have been determined.

Clinical Study of the Treatment of Klebsiella pneumoniae with Comprehensive Nursing Intervention Combined with New Nano Silver

2020 ◽  
Vol 20 (10) ◽  
pp. 6063-6069
Author(s):  
Shenghua Cao ◽  
Xiaoqian Wu ◽  
Jianling Zhao ◽  
Xinhong Jia
Keyword(s):  
Klebsiella Pneumoniae ◽  
Nursing Intervention ◽  
Bactericidal Effect ◽  
Inhibitory Effect ◽  
Control Group ◽  
Nano Silver ◽  
Clinical Nurses ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Management Modes

To investigate the inhibitory effect of new nano silver (nAg-NPs) on Klebsiella pneumoniae producing extended spectrum β-lactamases (EBLs). Clinical interventions are mainly directed to inpatients, or patients with obvious discomfort, symptoms, and signs needing outpatient examination, referral, and clear diagnosis. We randomly selected 88 patients from the rehabilitation department of our hospital from November 2017 to June 2019, and divided them into observation and control groups by drawing lots. Taking ESBL K. pneumoniae as the research object, the bactericidal effect of nAg-NPs was determined using the coating method; the minimal inhibitory concentration (MIC) was measured using the broth microdilution method, and the mechanism of action of nAg-NPs on ESBL K. pneumoniae was evaluated by electron microscopy. After the implementation of different nursing management modes, the incidence of risk events in the observation group was significantly lower than that in the control group, and nursing satisfaction was significantly higher than that in the control group. nAg-NPs (≥0.5 g/mL) had 100% bactericidal effect on ESBL K. pneumoniae, 0.05 g/mL nAg-NPs had obvious bactericidal effect on ESBL K. pneumoniae, 5 g/mL nAg-NPs had obvious bactericidal effect on ESBL K. pneumoniae for 5, 15, 30 and 60 min. Additionally, nAg-NPs showed 3.12 g/mL of MIC. Furthermore, nAg-NPs had a significant effect on the morphology of K. pneumoniae. nAg-NPs shows obvious inhibitory effect on ESBL K. pneumoniae. These results will provide an experimental basis for the further study and clinical application of nAg-NPs with the help of clinical nurses.

scholarly journals Resistance phenotype and molecular epidemiology of Carbapenem-resistant Klebsiella pneumoniae isolates in Shanghai

2020 ◽  
Author(s):  
Jue Zhang ◽  
Wenxia Zhang ◽  
Hongyou Chen ◽  
Chen Chen ◽  
Junhao Chen ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Klebsiella Pneumoniae ◽  
Molecular Epidemiology ◽  
Genetic Relatedness ◽  
Control Strategies ◽  
Microdilution Method ◽  
Carbapenem Resistant ◽  
Broth Microdilution Method ◽  
Polymerase Chain ◽  
Relationship Of

Abstract Background: The emergence and wide global spread of carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates are of great concern, and the aim of this study was to investigate drug resistance, molecular epidemiology, and genetic relationship of CRKP isolates from patients in Shanghai, China. Methods: A retrospective study was conducted from April 2018 to July 2019, and a total of 133 CRKP isolates were collected. Antimicrobial susceptibility was determined by VITEK-2 automated microbiology analyzer platform (bioMérieux, France) and the broth microdilution method. Polymerase chain reaction (PCR) assays were used to investigate the presence of drug resistance genes. A modified carbapenem inactivation method (mCIM) was performed to detect carbapenemases. Multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) were conducted for genetic relatedness of 50 CRKP isolates selected. Results: Among 670 isolates of K. pneumoniae, 133 (19.85%) strains were identified as carbapenem-resistant K. pneumoniae (CRKP), of which, 76.69% (102/133) strains were isolated from ICUs. All the 133 CRKP isolates were found to be carbapenemase-producers and harbor blaKPC-2 gene. No other carbapenemase genes of blaNDM, blaOXA−48, blaVIM, and blaIMP were detected. Furthermore, β-lactamase genes of blaSHV, blaCTX, and blaTEM were the most common resistance-associated genes among these KPC-2 producing isolates. All the 133 CRKP strains displayed more than 95% of resistance to cephalosporins and carbapenems, except for gentamicin, Trimethoprim-sulfamethoxazole, amikacin, tigecycline and colistin. The most common sequence type was ST11, accounting for 90.0% of the 50 CRKP selected, followed by ST15 (10%). PFGE analysis clustered the 50 KPC-2-producing isolates into seven (A-G) distinct clonal clusters at 85% cut off. Of which, cluster A and G were the two major clusters, accounting for the majority of the strains collected in emergency ICU and neurosurgical ICU. And all the strains of cluster D and E were collected in cardiothoracic surgery ICU, expect for one strain collected in one outpatient. Conclusion: The KPC-2-producing K.pneumoniae belonged to ST11 was widely disseminated in ICUs, and active and effective surveillance of infection control strategies was initiated to limit the spread of CRKP strains.

scholarly journals In Vitro Activity of Eravacycline in Combination with Colistin Against Carbapenem-Resistant A. baumannii Isolates

2019 ◽  
Author(s):  
H. Selcuk Ozger ◽  
Tugba Cuhadar ◽  
Serap Suzuk Yildiz ◽  
Zehra Demirbas Gulmez ◽  
Murat Dizbay ◽  
...  
Keyword(s):  
Therapeutic Option ◽  
Vitro Activity ◽  
Synergistic Activity ◽  
In Vitro Activity ◽  
Broth Microdilution ◽  
Similar Activity ◽  
Microdilution Method ◽  
Carbapenem Resistant ◽  
Broth Microdilution Method

AbstractThe synergistic activity of eravacycline in combination with colistin on carbapenem-resistant A.baumannii (CRAB) isolates was evaluated in this study. Minimum inhibitory concentrations (MICs) of eravacycline and colistin were determined by the broth microdilution method. MICs values ranged between 1 to 4 mg and 0,5 to 128 mg/L for eravacycline and colistin, respectively. In-vitro synergy between eravacycline and colistin was evaluated by using the chequerboard methodology. Synergistic activity was found in 10 % of the strains, and additive effect in 20 %. No antagonism was detected. Similar activity was also observed in colistin resistant CRAB isolates. The result of this study indicates that eravacycline and colistin combination may be a potential therapeutic option for the treatment of CRAB related infections.

scholarly journals In Vitro Activities of Ceftazidime–Avibactam and Aztreonam–Avibactam at Different Inoculum Sizes of Extended-Spectrum β-Lactam-Resistant Enterobacterales Blood Isolates

Antibiotics ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1492
Author(s):  
Moonsuk Bae ◽  
Taeeun Kim ◽  
Joung Ha Park ◽  
Seongman Bae ◽  
Heungsup Sung ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Klebsiella Pneumoniae ◽  
In Vitro Activity ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Extended Spectrum ◽  
Broth Microdilution Method ◽  
Tertiary Center ◽  
Inoculum Effect

β-lactam–avibactam combinations have been proposed as carbapenem-sparing therapies, but little data exist on their in vitro activities in infections with high bacterial inocula. We investigated the in vitro efficacies and the inoculum effects of ceftazidime–avibactam and aztreonam–avibactam against extended-spectrum β-lactam-resistant Enterobacterales blood isolates. A total of 228 non-repetitive extended-spectrum β-lactam-resistant Escherichia coli and Klebsiella pneumoniae blood isolates were prospectively collected in a tertiary center. In vitro susceptibilities to ceftazidime, aztreonam, meropenem, ceftazidime–avibactam, and aztreonam–avibactam were evaluated by broth microdilution method using standard and high inocula. An inoculum effect was defined as an eightfold or greater increase in MIC when tested with the high inoculum. Of the 228 isolates, 99% were susceptible to ceftazidime–avibactam and 99% had low aztreonam–avibactam MICs (≤8 mg/L). Ceftazidime–avibactam and aztreonam–avibactam exhibited good in vitro activities; MIC50/MIC90 values were 0.5/2 mg/L, 0.125/0.5 mg/L, and ≤0.03/0.25 mg/L, respectively, and aztreonam–avibactam was more active than ceftazidime–avibactam. The frequencies of the inoculum effect with ceftazidime–avibactam and aztreonam–avibactam were lower than with meropenem (14% vs. 38%, p < 0.001 and 30% vs. 38%, p = 0.03, respectively). The β-lactam-avibactam combinations could be useful as carbapenem-sparing strategies, and aztreonam–avibactam has the better in vitro activity but is more subject to the inoculum effect than ceftazidime–avibactam.

scholarly journals The Anti-Staphylococcal Potential of Ethanolic Polish Propolis Extracts

Molecules ◽  
2019 ◽  
Vol 24 (9) ◽  
pp. 1732 ◽  
Author(s):  
Katarzyna Grecka ◽  
Piotr M. Kuś ◽  
Piotr Okińczyc ◽  
Randy W. Worobo ◽  
Justyna Walkusz ◽  
...  
Keyword(s):  
Hplc Analysis ◽  
Bactericidal Effect ◽  
Gram Negative Bacteria ◽  
Broth Microdilution ◽  
Inhibit Protein Synthesis ◽  
Gram Negative ◽  
E Coli ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Ethanol Extracts

The principal objective of this study was to determine the anti-staphylococcal potential of ethanol extracts of propolis (EEPs). A total of 20 samples of propolis collected from apiaries located in different regions of Poland were used in the study. The two-fold broth microdilution method revealed some important differences in the antimicrobial activity of investigated EEPs. Up to the concentration of 4096 µg/mL no activity was observed against Gram-negative bacteria (E. coli and P. aeruginosa). Staphylococci exhibited much higher susceptibility. The highest efficiency observed for EEP12 and EEP20 (MIC values ranged between 32 and 256 µg/mL). However, the achievement of bactericidal effect usually required higher concentrations. In the case of clinical isolates of S. aureus MBC values for EEP12 and EEP20 ranged from 512 to 1024 µg/mL. The HPLC analysis revealed that these two products contained a higher concentration of flavonoids (flavonols, flavones, and flavanones) compared to other investigated EEPs. In checkerboard test, a synergistic anti-staphylococcal effect was observed for the action of EEP20 in combination with amikacin, kanamycin, gentamycin, tetracycline, and fusidic acid (all these antibiotics inhibit protein synthesis). Moreover, the investigated EEPs effectively eradicated staphylococcal biofilm. The obtained results clearly confirm the high anti-staphylococcal potential of propolis harvested in Polish apiaries.

scholarly journals Evaluation of resazurin-based assay for rapid detection of polymyxin-resistant gram-negative bacteria

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Huaiyu Jia ◽  
Renchi Fang ◽  
Jie Lin ◽  
Xuebin Tian ◽  
Yajie Zhao ◽  
...  
Keyword(s):  
Rapid Detection ◽  
Visual Detection ◽  
Detection Method ◽  
Gram Negative Bacteria ◽  
Broth Microdilution ◽  
Colistin Resistance ◽  
Acinetobacter Baumanii ◽  
Gram Negative ◽  
Microdilution Method ◽  
Broth Microdilution Method

Abstract Background Colistin resistance is considered a serious problem due to a lack of alternative antibiotics. The Rapid ResaPolymyxin Acinetobacter/Pseudomonas NP test is a resazurin reduction-based technique that relies on the visual detection of bacterial growth in the presence of a defined concentration of colistin. The aim of this study was to evaluate the performance of the Rapid ResaPolymyxin Acinetobacter/Pseudomonas NP test in the detection of colistin susceptibility in common clinical Gram-negative bacteria. Results A total of 253 clinical isolates from a teaching hospital, including Acinetobacter baumanii (n = 58, 8 colistin-resistant), Pseudomonas aeruginosa (n = 61, 11 colistin-resistant), Klebsiella pneumoniae (n = 70, 20 colistin-resistant) and Escherichia coli (n = 64, 14 colistin-resistant) were tested in this study. The sensitivity and specificity of the Rapid ResaPolymyxin Acinetobacter/Pseudomonas NP test compared to Broth microdilution method was 100 and 99%, respectively. Conclusions Our results suggest that Rapid ResaPolymyxin Acinetobacter/Pseudomonas NP test could be used as an accurate detection method for colistin resistance.

The role of the bla KPC gene in antimicrobial resistance of Klebsiella pneumoniae

2019 ◽  
Author(s):  
Atossa Ghasemnejad ◽  
Monir Doudi ◽  
Nour Amirmozafari
Keyword(s):  
Klebsiella Pneumoniae ◽  
Antimicrobial Susceptibility ◽  
Diffusion Method ◽  
Disc Diffusion ◽  
Broth Microdilution ◽  
Disc Diffusion Method ◽  
Biochemical Tests ◽  
Microdilution Method ◽  
Broth Microdilution Method

Background and Objectives: Klebsiella pneumoniae isolates that produce K. pneumoniae carbapenemase (KPC) have be- come a grave concern for the treatment of infections. KPC-producing strains are not only able to hydrolyze carbapenems but are also resistant to a variety of β-lactam and non-β-lactam antibiotics. The present study evaluated the prevalence of bla in K. pneumoniae infections and determined the antimicrobial susceptibility of the isolates. Materials and Methods: The K. pneumoniae isolates were identified by biochemical tests and confirmed by genotyping. The modified Hodge test (MHT) was performed to detect carbapenemases, and antimicrobial susceptibility was determined for all isolates by the disc diffusion method. Also, for MHT-positive isolates, supposed to carbapenemases isolates, broth microdilution method was used to measure the minimum inhibitory concentrations (MICs) of meropenem and colistin. Results: The bla KPC genotypic evaluation revealed that only 5 of 96 isolates carried bla genes. Antimicrobial pattern showed that isolates carrying bla were resistant to cefepime, ticarcillin/tazobactam, and aztreonam discs. Also, results of broth microdilution method showed that KPC-producing K. pneumoniae was resistant to meropenem and colistin, according to the CLSI and EUCAST. Conclusion: In this study nearly half the isolates showed carbapenemase activity as shown by MHT results, but only few of them were carrying bla . Thus bla gene is not the main cause of resistance spread to carbapenems in Isfahan, Iran.

Etomidate inhibits the growth of MRSA and exhibits synergism with oxacillin

2020 ◽  
Vol 15 (17) ◽  
pp. 1611-1619
Author(s):  
Lívia G do AV Sá ◽  
Cecília R da Silva ◽  
João B de A Neto ◽  
Thiago M Cândido ◽  
Leilson C de Oliveira ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Antimicrobial Activity ◽  
Cell Death ◽  
Antibacterial Activity ◽  
Antibacterial Effect ◽  
Broth Microdilution ◽  
Action Mechanism ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Mrsa Strains

Aim: The purpose of this study was to evaluate the antimicrobial activity of the anesthetic etomidate against strains of MRSA and biofilms. Materials & methods: The antibacterial effect of etomidate was assessed by the broth microdilution method. To investigate the probable action mechanism of the compound flow cytometry techniques were used. Results: MRSA strains showed MIC equal to 500 and 1000 μg/ml of etomidate. Four-fifths (80%) of the tested MRSA strains demonstrated synergistic effect with oxacillin. Etomidate also showed activity against MRSA biofilm at concentration of 250 μg/ml. Cytometric analysis revealed that the cells treated with etomidate leading to cell death, probably by apoptosis. Conclusion: Etomidate showed antibacterial activity against MRSA.

scholarly journals A novel method for measuring phenotypic colistin resistance in Escherichia coli populations from chicken flocks

2020 ◽  
Author(s):  
Nhung Thi Nguyen ◽  
Nguyen Thi Phuong Yen ◽  
Nguyen Van Ky Thien ◽  
Nguyen Van Cuong ◽  
Bach Tuan Kiet ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Production Cycle ◽  
Broth Microdilution ◽  
Colistin Resistance ◽  
E Coli ◽  
Microdilution Method ◽  
Faecal Samples ◽  
Broth Microdilution Method ◽  
Field Samples ◽  
Over Time

ABSTRACTColistin is extensively used in animal production in many low- and middle-income countries. There is a need to develop methodologies to benchmark and monitor changes in resistance in commensal bacterial populations in farms. We aimed to evaluate the performance of a broth microdilution method based on culturing a pooled Escherichia coli suspension (30-50 organisms) from each sample. In order to confirm the biological basis and sensitivity of the method, we prepared 16 standard suspensions containing variable ratios of colistin-susceptible and mcr-1 encoded colistin-resistant E. coli which were grown in 2mg/L colistin. The optical density (OD600nm) readings over time were used to generate a growth curve, and were adjusted to the values obtained in the absence of colistin. The median limit of detection of the method was 1 colistin-resistant in 104 susceptible colonies [1st - 3rd quartile, 1:102 – 1:105]. We applied this method to 108 pooled faecal samples from 36 chicken flocks in the Mekong Delta (Vietnam) over the production cycle. The correlation between this method and the prevalence of colistin resistance in individual colonies harvested from field samples, determined by the Minimum Inhibitory Concentration (MIC), was established. The overall prevalence of colistin resistance at sample and isolate level was 38.9% and 19.4%, respectively. Increased colistin resistance was associated with recent (2 weeks) use of colistin and other, non-colistin antimicrobials (OR=3.67 and OR=1.84, respectively). Our method is a sensitive and affordable approach to monitor changes in colistin resistance in pooled E. coli populations from faecal samples over time.IMPORTANCEColistin (polymyxin E) is an antimicrobial with poor solubility properties, and therefore broth microdilution is the only appropriate method for testing colistin resistance. However, estimating colistin resistance in commensal mixed Escherichia coli populations is laborious since it requires individual colony isolation, identification and susceptibility testing. We developed a growth-based microdilution method suitable for pooled faecal samples. We validated the method by comparing it with results from individual MIC testing of 909 E. coli isolates. We used the method to investigate phenotypic colistin resistance in 108 pooled faecal samples from 36 healthy chicken flocks, each sampled three times over the production cycle. A higher level of resistance was seen in flocks recently supplemented with colistin in drinking water, although the observed generated resistance was short-lived. Our method is affordable, and may potentially be integrated into surveillance systems aiming at estimating the prevalence of resistance at colony level in flocks/herds. Furthermore, it may also be adapted to other complex biological systems, such as farms and abattoirs.

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