scholarly journals 201. Frequency of Pseudomonas aeruginosa (PA) Discrete Inner Colonies and Comparison of Minimal Inhibitory Concentration (MIC) Values between Parent and Inner Colony Isolates Following Fosfomycin Disk Diffusion (DD) Testing

2021 ◽  
Vol 8 (Supplement_1) ◽  
pp. S123-S123
Author(s):  
Dina Zheng ◽  
Morgan L Bixby ◽  
Elizabeth C Smith ◽  
Jadyn C Anderson ◽  
Phillip J Bergen ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Antibiotic Resistance ◽  
High Frequency ◽  
Susceptibility Testing ◽  
Inhibitory Concentration ◽  
Multidrug Resistant ◽  
Broth Microdilution ◽  
Zone Of Inhibition ◽  
Bmd Testing

Abstract Background Fosfomycin combination therapy is a potential approach for treatment of multidrug-resistant (MDR) PA infections despite a lack of approved susceptibility breakpoints for this organism. While DD testing is commonly used for fosfomycin, growth of discrete inner colonies (IC) within the zone of inhibition has been observed for multiple organisms following DD. Criteria recommended by CLSI and EUCAST are contradictory for interpreting these inner colonies. We therefore sought to determine the frequency of inner colonies and MIC differences between PA parent-inner colony pairs from an international isolate collection. Methods A convenience collection of 198 clinical PA isolates from three U.S institutions (n = 82), two Australian institutions (n = 72), and the CDC & FDA Antibiotic Resistance Isolate Bank (n = 44) were included. Fosfomycin MIC values were determined in duplicate on separate days by DD and broth microdilution (BMD) testing. For parent isolates with discrete IC observed during DD, IC isolates were subcultured and MIC values were determined and then compared to their corresponding parent isolates. MIC values were interpreted using CLSI Escherichia coli (EC) breakpoints (susceptible: MIC ≤ 64 μg/mL, intermediate: MIC = 128, resistant: MIC ≥ 256 μg/mL). Results Parent isolate BMD MIC values ranged from < 4 to > 256 μg/mL while IC isolate BMD MIC values ranged from 128 to > 1024 μg/mL. MIC50/90 values were 128/256 μg/mL and > 1024/ > 1024 μg/mL for the parent and IC isolates, respectively. A high frequency of 45% (89/198) of parent isolates displayed discrete IC which also demonstrated a higher frequency of resistance (97.8%) compared to the parent isolates (23.7%). Conclusion IC MIC values were higher overall compared to parent MIC values, with an average fold difference of ~18 between the parent-inner colony pairs. The frequency of IC found in this study (45%) is considerably higher than previously observed in EC clinical isolates. These data highlight the need to further investigate the importance of these IC and warrant caution for extrapolation of EC breakpoints for fosfomycin susceptibility testing against PA. Disclosures All Authors: No reported disclosures

Antibiotic Resistance Profile of Commensal Escherichia coli Isolated from Broiler Chickens in Qatar

2017 ◽  
Vol 81 (2) ◽  
pp. 302-307 ◽  
Author(s):  
Nahla O. Eltai ◽  
Elmoubasher A. Abdfarag ◽  
Hamad Al-Romaihi ◽  
Eman Wehedy ◽  
Mahmoud H. Mahmoud ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Broiler Chickens ◽  
Susceptibility Testing ◽  
Multidrug Resistant ◽  
Test Method ◽  
Health Concern ◽  
E Coli ◽  
Extended Spectrum ◽  
Stewardship Program

ABSTRACT Antibiotic resistance (AR) is a growing public health concern worldwide, and it is a top health challenge in the 21st century. AR among Enterobacteriaceae is rapidly increasing, especially in third-generation cephalosporins and carbapenems. Further, strains carrying mobilized colistin resistance (mcr) genes 1 and 2 have been isolated from humans, food-producing animals, and the environment. The uncontrolled use of antibiotics in food-producing animals is a major factor in the generation and spread of AR. No studies have been done to evaluate AR in the veterinary sector of Qatar. This study aimed at establishing primary baseline data for the prevalence of AR among food-producing animals in Qatar. Fecal samples (172) were obtained from two broiler farms and one live bird market in Qatar, and 90 commensal Escherichia coli bacteria were isolated and subjected to susceptibility testing against 16 clinically relevant antibiotics by using the E-test method. The results found that 81 (90%) of 90 isolates were resistant to at least one antibiotic, 14 (15.5%) of 90 isolates were colistin resistant, 2 (2.2%) of 90 isolates were extended-spectrum β-lactamase producers, and 2 (2.2%) of 90 isolates were multidrug resistant to four antibiotic classes. Extended-spectrum β-lactamase–producing E. coli and colistin-resistant isolates were confirmed by using double-disc susceptibility testing and PCR, respectively. Such a high prevalence of antibiotic-resistant E. coli could be the result of a long application of antibiotic treatment, and it is an indicator of the antibiotic load in food-producing animals in Qatar. Pathogens carrying AR can be easily transmitted to humans through consumption of undercooked food or noncompliance with hygiene practices, mandating prompt development and implementation of a stewardship program to control and monitor the use of antibiotics in the community and agriculture.

scholarly journals Detecting In-Vitro Colistin Resistance- A Comparative Study Between Broth Microdilution Versus Vitek-2 For Colistin Susceptibility Testing

2020 ◽  
Vol 7 (7) ◽  
pp. A336-340
Author(s):  
Hena Butta ◽  
Leena Mendiratta ◽  
Raman Sardana ◽  
Kirti Gilotra ◽  
Sana Hasan ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Clinical Microbiology ◽  
Susceptibility Testing ◽  
Clinical Microbiology Laboratory ◽  
Microbiology Laboratory ◽  
Broth Microdilution ◽  
Major Error ◽  
Acinetobacter Baumanii ◽  
Vitek 2

Background: Susceptibility testing for polymyxins is a great challenge for a Clinical Microbiology laboratory. There are several methodological issues associated with MIC (Minimum Inhibitory Concentration) determination of colistin. Methods: In our study, we have compared the results of colistin susceptibility testing by Automated system (Vitek-2, Biomerieux, France) with the reference Broth Microdilution method (BMD) to identify the type of discrepancies by Vitek-2 method and thus develop a practical and accurate approach for colistin susceptibility testing in a Clinical Microbiology laboratory. A total of 730 strains of Gram negative bacteria [Escherichia coli (325), Klebsiella sp.(346), Acinetobacter baumanii complex (37) and Pseudomonas aeruginosa (22)] from 485 patents were tested simultaneously by BMD and Vitek-2 method for colistin susceptibility testing. Results: The Essential agreement (EA), Categorical agreement (CA), Very major error (VME) and Major error (ME) rates for Klebsiella sp. were 87.3%, 89.3%, 8% and 2.3% respectively, for Escherichia coli were 88.3%, 89.5%, 9.2% and 1.2%  respectively, for Acinetobacter baumannii complex were 89.1%, 91.8%, 8.1% and 0% respectively, for Pseudomonas aeruginosa were 68.1%, 72.7%, 0% and 27.2% respectively. Conclusions: Colistin susceptibility testing by Vitek-2 method is an easily adoptable method and the results of Vitek-2 with reference to BMD are acceptable to a great extent in Klebsiella sp., Escherichia coli and Acinetobacter baumanii complex. So, we believe that Vitek-2 method may be used for colistin susceptibility testing in low risk patients. However, BMD should be used in high risk immunosupressed and immunocompromised patients who are admitted in critical care units. For Pseudomonas aeruginosa, BMD should be routinely used.

scholarly journals In Vitro Activity of Colistin (Polymyxin E) against 3,480 Isolates of Gram-Negative Bacilli Obtained from Patients in Canadian Hospitals in the CANWARD Study, 2007-2008

2009 ◽  
Vol 53 (11) ◽  
pp. 4924-4926 ◽  
Author(s):  
A. Walkty ◽  
M. DeCorby ◽  
K. Nichol ◽  
J. A. Karlowsky ◽  
D. J. Hoban ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Acinetobacter Baumannii ◽  
Multidrug Resistant ◽  
Vitro Activity ◽  
In Vitro Activity ◽  
Broth Microdilution ◽  
Gram Negative ◽  
Polymyxin E

ABSTRACT The in vitro activity of colistin was evaluated versus 3,480 isolates of gram-negative bacilli using CLSI broth microdilution methods. The MIC90 of colistin was ≤2 μg/ml against a variety of clinically important gram-negative bacilli, including Escherichia coli, Klebsiella spp., Enterobacter spp., Acinetobacter baumannii, and Pseudomonas aeruginosa. All multidrug-resistant (n = 76) P. aeruginosa isolates were susceptible to colistin (MIC, ≤2 μg/ml). These data support a role for colistin in the treatment of infections caused by multidrug-resistant P. aeruginosa.

scholarly journals Performance of Four Fosfomycin Susceptibility Testing Methods against an International Collection of Clinical Pseudomonas aeruginosa Isolates

2020 ◽  
Vol 58 (10) ◽  
Author(s):  
Elizabeth C. Smith ◽  
Hunter V. Brigman ◽  
Jadyn C. Anderson ◽  
Christopher L. Emery ◽  
Tiffany E. Bias ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Susceptibility Testing ◽  
Wide Spectrum ◽  
Multidrug Resistant ◽  
Supporting Evidence ◽  
Broth Microdilution ◽  
Testing Methods ◽  
Content Type ◽  
E Coli ◽  
Agar Dilution

ABSTRACT Fosfomycin has been shown to have a wide spectrum of activity against multidrug-resistant Gram-negative bacteria; however, breakpoints have been established only for Escherichia coli or Enterobacterales per the Clinical and Laboratory Standards Institute (CLSI) and the European Committee on Antimicrobial Susceptibility Testing (EUCAST), respectively. A lack of additional organism breakpoints limits clinical use of this agent and has prompted extrapolation of these interpretive categories to other organisms like Pseudomonas aeruginosa without supporting evidence. Further complicating the utility of fosfomycin is the specified method for MIC determination, namely, agar dilution, which is not widely available and is both labor and time intensive. We therefore sought to determine the susceptibility of a large international collection of P. aeruginosa isolates (n = 198) to fosfomycin and to compare testing agreement rates across four methods: agar dilution, broth microdilution, disk diffusion, and Etest. Results were interpreted according to CLSI E. coli breakpoints, with 49.0 to 85.8% considered susceptible, dependent upon the testing method used. Epidemiological cutoff values were calculated and determined to be 256 μg/ml and 512 μg/ml for agar dilution and broth microdilution, respectively. Agreement rates were analyzed using both agar dilution and broth microdilution with a resulting high essential agreement rate of 91.3% between the two susceptibility testing methods. These results indicate that broth microdilution may be a reliable method for fosfomycin susceptibility testing against P. aeruginosa and stress the need for P. aeruginosa-specific breakpoints.

scholarly journals Wild-type cutoff for Apramycin against Escherichia coli

2020 ◽  
Author(s):  
Xiuying Zhang ◽  
Yuqi Yang ◽  
Tianshi Xiao ◽  
Jiarui Li ◽  
Ping Cheng ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Resistance Genes ◽  
Susceptibility Testing ◽  
Inhibitory Concentration ◽  
Multidrug Resistant ◽  
Wild Type ◽  
Research Papers ◽  
E Coli ◽  
Antibacterial Susceptibility

Abstract Background Apramycin is used exclusively for the treatment of Escherichia coli ( E.coli ) infections in swine around the world since the early 1980s. Recently, many research papers have demonstrated that apramycin has obvious in vitro activity against multidrug-resistant Enterobacteriaceae isolated in hospitals. Therefore, ensuring the proper use of apramycin in veterinary clinics is of great significance of public health. The objectives of this study were to develop a wild-type cutoff for apramycin against E.coli using a statistical method recommended by Clinical and Laboratory Standards Institute (CLSI) and to investigate the prevalence of resistance genes that confer resistance to apramycin in E. coli . Results Antibacterial susceptibility testing of 1230 E.coli clinical isolates from swine were determinded by broth microdilution testing according to the CLSI document M07-A9. A total number of 310 E.coli strains from different minimum inhibitory concentration (MIC) subsets (0.5-256 µg/mL) were conveniently selected for the detection of resistance genes ( aac(3)-IV ; npmA ; apmA ) in E. coli by PCR. The percentage at each MIC (0.5, 1, 2, 4, 8, 16, 32, 64, 128, and 256 µg/mL) was 0.08%, 0.08%, 0.16%, 2.93%, 31.14%, 38.86%, 12.85%, 2.03%, 1.46%, and 10.41%. The MIC 50 and MIC 90 were 16 and 64 µg/mL. All the 310 E.coli isolates were negative for npmA and apmA gene, and only the aac(3)-IV gene was detected in this study. Conclusions The wild-type cutoff for apramycin against E.coli was defined as 32 µg/mL. The prevelance of aac(3)-IV gene mainly concentrated in these MIC subsets ‘MIC ≥ 64 µg⁄ mL’, which indicates that the wild-type cutoff established in our study is reliable. The wild-type cutoff offers interpretion criteria of apramycin susceptibility testing of E.coli .

scholarly journals Wild-type cutoff for Apramycin against Escherichia coli

2020 ◽  
Author(s):  
Yuqi Yang ◽  
Tianshi Xiao ◽  
Jiarui Li ◽  
Ping Cheng ◽  
Fulei Li ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Resistance Genes ◽  
Susceptibility Testing ◽  
Inhibitory Concentration ◽  
Multidrug Resistant ◽  
Wild Type ◽  
Research Papers ◽  
E Coli ◽  
The World

Abstract Background：Apramycin is used exclusively for the treatment of Escherichia coli (E.coli) infections in swine around the world since the early 1980s. Recently, many research papers have demonstrated that apramycin has significant in vitro activity against multidrug-resistant E.coli isolated in hospitals. Therefore, ensuring the proper use of apramycin in veterinary clinics is of great significance of public health. The objectives of this study were to develop a wild-type cutoff for apramycin against E.coli using a statistical method recommended by Clinical and Laboratory Standards Institute (CLSI) and to investigate the prevalence of resistance genes that confer resistance to apramycin in E. coli.Results: Apramycin susceptibility testing of 1230 E.coli clinical isolates from swine were determinded by broth microdilution testing according to the CLSI document M07-A9. A total number of 310 E.coli strains from different minimum inhibitory concentration (MIC) subsets (0.5-256 µg/mL) were selected for the detection of resistance genes (aac(3)-IV; npmA; apmA) in E. coli by PCR. The percentage of E. coli isolates at each MIC (0.5, 1, 2, 4, 8, 16, 32, 64, 128, and 256 µg/mL) was 0.08%, 0.08%, 0.16%, 2.93%, 31.14%, 38.86%, 12.85%, 2.03%, 1.46%, and 10.41%. The MIC50 and MIC90 were 16 and 64 µg/mL. All the 310 E.coli isolates were negative for npmA and apmA gene, and only the aac(3)-IV gene was detected in this study.Conclusions: The wild-type cutoff for apramycin against E.coli was defined as 32 µg/mL. The prevelance of aac(3)-IV gene mainly concentrated in these MIC subsets ‘MIC ≥ 64 µg⁄ mL’, which indicates that the wild-type cutoff established in our study is reliable. The wild-type cutoff offers interpretion criteria of apramycin susceptibility testing of E.coli.

scholarly journals Antibacterial Property of Extract of Erveniastrum nepalense (Edible Lichen) Collected from Hilly Regions of Eastern Nepal

2019 ◽  
Vol 6 ◽  
pp. 51-58
Author(s):  
Saraswati Yonghang ◽  
Suman Rai ◽  
Shiv Nandan Sah
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Bacillus Subtilis ◽  
Minimum Inhibitory Concentration ◽  
Inhibitory Concentration ◽  
Antibacterial Property ◽  
Diffusion Method ◽  
Zone Of Inhibition ◽  
Klebsiella Spp

Objectives: To evaluate the antibacterial property of Everniastrum nepalense(edible lichen)collected from eastern part of Nepal and determine Minimum Inhibitory Concentration (MIC) of lichen extract. Methods: Everniastrum nepalense was collected from local Rai and Limbu community in a plastic bag from four hilly districts (Pachthar, Taplejung, Dhankuta and Bhojpur) of Eastern, NepaMoisture content in lichen samples were removed by air drying and grinded to powdery form. The methanolic extracts of lichens of different places were prepared by solvent extraction process using Soxhlet apparatus and tested against human pathogenic bacteria by disc diffusion method. Then, Minimum Inhibitory Concentration (MIC) of lichen extracts was determined using well diffusion method. Results: The lichens extract against the test bacterial isolates were performed by agar well diffusion method. Overall, it was observed that all these lichen extracts from Eastern Nepal had inhibitory effect on both gram-positive and gram-negative bacteria. Out of seven bacterial samples used, all bacterial samples were inhibited by the lichen extracts except Escherichia coli. The effect of lichen extract collected from Bhojpur district had maximum zone of inhibition against Staphylococcus aureus, Salmonella Typhi and Klebsiella spp were found to be 13 mm, 14 mm and 14 mm respectively. Similarly, zone of inhibition against Bacillus subtilis was found to be 17 mm from samples of Dhankuta, which was highest value than other 3 districts viz; Bhojpur, Taplejung and Pachthar District. Likewise, Pseudomonas aeruginosa showed highest inhibition value i.e. 18 mm on Pachthar sample whereas, Shigella showed 15 mm on Dhankuta sample. This study revealed that inhibitory capacity of edible lichen (Everniastrum nepalense) against test bacteria was not the same. It varied from place to place. Conclusion: This study has concluded that Everniastrum nepalensehas potential antibacterial property against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Salmonella spp, Shigella spp, Klebsiella spp and Pseudomonas aeruginosa except E. coli along with nutritional value and can be used as safe alternative and economic herbal medicine to treat infectious diseases.

scholarly journals Wild-type cutoff for Apramycin against Escherichia coli

2020 ◽  
Author(s):  
Yuqi Yang ◽  
Tianshi Xiao ◽  
Jiarui Li ◽  
Ping Cheng ◽  
Fulei Li ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Resistance Genes ◽  
Susceptibility Testing ◽  
Inhibitory Concentration ◽  
Multidrug Resistant ◽  
Wild Type ◽  
Research Papers ◽  
E Coli ◽  
The World

Abstract Background：Apramycin is used exclusively for the treatment of Escherichia coli (E.coli) infections in swine around the world since the early 1980s. Recently, many research papers have demonstrated that apramycin has significant in vitro activity against multidrug-resistant E.coli isolated in hospitals. Therefore, ensuring the proper use of apramycin in veterinary clinics is of great significance of public health. The objectives of this study were to develop a wild-type cutoff for apramycin against E.coli using a statistical method recommended by Clinical and Laboratory Standards Institute (CLSI) and to investigate the prevalence of resistance genes that confer resistance to apramycin in E. coli.Results: Apramycin susceptibility testing of 1230 E.coli clinical isolates from swine were determinded by broth microdilution testing according to the CLSI document M07-A9. A total number of 310 E.coli strains from different minimum inhibitory concentration (MIC) subsets (0.5-256 µg/mL) were selected for the detection of resistance genes (aac(3)-IV; npmA; apmA) in E. coli by PCR. The percentage of E. coli isolates at each MIC (0.5, 1, 2, 4, 8, 16, 32, 64, 128, and 256 µg/mL) was 0.08%, 0.08%, 0.16%, 2.93%, 31.14%, 38.86%, 12.85%, 2.03%, 1.46%, and 10.41%. The MIC50 and MIC90 were 16 and 64 µg/mL. All the 310 E.coli isolates were negative for npmA and apmA gene, and only the aac(3)-IV gene was detected in this study.Conclusions: The wild-type cutoff for apramycin against E.coli was defined as 32 µg/mL. The prevelance of aac(3)-IV gene mainly concentrated in these MIC subsets ‘MIC ≥ 64 µg⁄ mL’, which indicates that the wild-type cutoff established in our study is reliable. The wild-type cutoff offers interpretion criteria of apramycin susceptibility testing of E.coli.

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