Antimicrobial Susceptibility Test
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F1000Research ◽  
2021 ◽  
Vol 10 ◽  
pp. 1093
Author(s):  
Pablo Alejandro Millones Gómez ◽  
Lidia Yileng Tay Chu Jon ◽  
Dora Jesús Maurtua Torres ◽  
Reyma Evelyn Bacilio Amaranto ◽  
Ingrit Elida Collantes Díaz ◽  
...  

Background: Natural products with antibacterial potential have begun to be tested on biofilm models, bringing us closer to understanding the response generated by the complex microbial ecosystems of the oral cavity. The objective of this study was to evaluate the antibacterial, antibiofilm, and cytotoxic activities and chemical compositions of Peruvian propolis in an in vitro biofilm of Streptococcus gordonii and Fusobacterium nucleatum. Methods: The experimental work involved a consecutive, in vitro, longitudinal, and double-blinded study design. Propolis samples were collected from 13 different regions of the Peruvian Andes. The disk diffusion method was used for the antimicrobial susceptibility test. The cytotoxic effect of propolis on human gingival fibroblasts was determined by cell viability method using the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay, and the effect of propolis on the biofilm was evaluated by confocal microscopy and polymerase chain reaction (PCR). Results: The 0.78 mg/mL and 1.563 mg/mL concentrations of the methanolic fraction of the chloroform residue of Oxapampa propolis showed effects on biofilm thickness and the copy numbers of the srtA gene of S. gordonii and the radD gene of F. nucleatum at 48 and 120 hours, and chromatography (UV, λ 280 nm) identified rhamnocitrin, isorhamnetin, apigenin, kaempferol, diosmetin, acacetin, glycerol, and chrysoeriol. Conclusions: Of the 13 propolis evaluated, it was found that only the methanolic fraction of Oxapampa propolis showed antibacterial and antibiofilm effects without causing damage to human gingival fibroblasts. Likewise, when evaluating the chemical composition of this fraction, eight flavonoids were identified.


Author(s):  
Alexander Winnett ◽  
Vinay Srinivasan ◽  
Matthew Davis ◽  
Tara Vijayan ◽  
Daniel Z. Uslan ◽  
...  

Background In the absence of antimicrobial susceptibility data, the institutional antibiogram is a valuable tool to guide clinicians in the empiric treatment of infections. However, there is a misunderstanding on how best to prepare cumulative antimicrobial susceptibility testing reports (CASTRs) to guide empiric therapy (e.g., routine antibiogram) versus monitoring antimicrobial resistance, with the former following guidance from the Clinical Laboratory Standards Institute (CLSI), and the latter from Center for Disease Control and Preventions National Healthcare Safety Network (NHSN). These criteria vary markedly in their exclusion or inclusion of isolates cultured repeatedly from the same patient. Methods We compared rates of non-susceptibility (NS)using annual data from a large teaching healthcare system subset to isolates eligible by either NHSN criteria or CLSI criteria. Results For a panel of the three most prevalent gram-negative pathogens in combination with clinically relevant antimicrobial agents (or priority pathogen-agent combinations, PPACs), we found that the inclusion of duplicate isolates by NHSN criteria yielded higher NS rates than when CLSI criteria (for which duplicate isolates are not included) were applied. Conclusions Patients with duplicate isolates may not be representative of antimicrobial resistance within a population. For this reason, users of CASTR data should carefully consider that the criteria used to generate these reports can impact resulting NS rates, and therefore maintain the distinction between CASTRs created for different purposes.


2021 ◽  
Vol 2021 ◽  
pp. 1-5
Author(s):  
Mojtaba Moosavian ◽  
Mahtab Khoshkholgh Sima ◽  
Nazanin Ahmad Khosravi ◽  
Effat Abbasi Montazeri

Antibiotic resistance mechanisms in Enterobacteriaceae are causative agents of global health problems. Bacterial infections due to multidrug resistance (MDR) may be mediated by the overexpression of efflux pumps. In this study, we investigated the prevalence of oqxA and oqxB genes as two encoding agents of efflux pumps and the determination of antibiotic resistance rate in clinical isolates of Enterobacteriaceae. In this study, 100 Enterobacteriaceae isolates collected from different clinical specimens of infectious patients, such as wounds, urine, blood, discharge, and abscesses except stool, were examined. Identification of the isolates was performed using standard biochemical tests such as TSI, citrate, urea, lysine, SIM, MR-VP, and gas production. The antimicrobial susceptibility test was carried out by the Kirby–Bauer disk diffusion method according to CLSI guidelines, and finally, the oqxA and oqxB genes were detected by the PCR method. Among 100 Enterobacteriaceae isolates, Escherichia coli and Enterobacter gergoviae were the most common isolates with 71% and 20%, respectively. Also, the lowest isolates belonged to Enterobacter cloacae (3%) and Klebsiella pneumoniae (1%). Out of 100 Enterobacteriaceae isolates, 37 isolates (37%) were positive for at least one of oqxA or oqxB genes, while both of these genes were detected among 12% of them. oqxAB genes were detected in 8 cases of 20 (40%) Enterobacter gergoviae and 4 cases of 71 (5.7%) E. coli isolates. The antimicrobial susceptibility test showed that all isolates (100%) were susceptible to imipenem, while the maximum resistance to piperacillin, ceftriaxone, and cefotaxime were 69%, 55%, and 55%, respectively. Also, the results of this study showed that antibiotic resistance in Enterobacteriaceae isolates caused by oqxAB genes is increasing among patients in Iran. Therefore, identification of resistant isolates and antibiotic monitoring programs are essential to prevent the spread of MDR isolates.


Author(s):  
Obiefuna O. I. ◽  
Mbah C. E. ◽  
Amlabu W.E.

The potentially major importance but currently unstudied trend of enteric bacterial contamination on surfaces of canned drinks forms the basis of the research. A study was carried out to determine the antimicrobial susceptibility of selected enteric bacteria on the surface of canned soft drinks and its handlers (palms of consumers) from selected tertiary institutions in Zaria. Two hundred and sixteen swabs were collected from the external surfaces of canned soft drinks and its handlers, thirty-six swabs each from cans and hand swabs were also collected from designated whole sellers known as Distributors. The samples were screened and analyzed using Spread Plate Method, Microgen GNA System for identification for enteric bacteria in three institutions in Zaria, Kaduna State. Kirby-Bauer disk diffusion method was employed for antimicrobial susceptibility test. The results showed that the total bacteria count of canned soft drinks and its handlers in the three institutions range from 1.0x104 to 3.0x107 cfu/ml. Fourteen species of the Family Enterobacteriaceae were identified. The predominant species observed on canned soft drinks were Citrobacter freundii and Klebsiella ozaenae while that of its handlers were Citrobacter freundii and Escherichia coli. Perfloxacin (66.7%) in ABU, perfloxacin (66.7%) in FCE and ciprofloxacin (88.9%) in POLY were highly sensitive against the isolates, while imipenem and ampicillin had (57.6%) in ABU, ofloxacin (73.3%) in FCE and Amoxicillin-Clavulanic (66.7%) in POLY were found to be non-susceptible. The study showed that surfaces of canned soft drinks and its handlers in Zaria are significantly contaminated with enteric bacteria. Hence, incorporation of routine check of canned drinks in the health system is required. There is low antimicrobial activity by the antibiotic against the isolates, this poses serious health implications and requires further investigation.


PLoS ONE ◽  
2021 ◽  
Vol 16 (11) ◽  
pp. e0259584
Author(s):  
Mona A. El-Zamkan ◽  
Hams M. A. Mohamed

This study is designed to discuss the antimicrobial resistance, virulence determinants and biofilm formation capacity of Enterococcus spp. isolated from milk of sheep and goat with subclinical mastitis in Qena, Egypt. The obtained isolates were identified by the VITEK2 system and 16S rDNA sequencing as E. faecalis, E. faecium, E. casseliflavus and E. hirae. Overall, E. faecalis and E. faecium were the dominant species recovered from mastitic milk samples. The antimicrobial susceptibility test evidenced multidrug resistance of the isolates against the following antimicrobials: oxacillin (89.2.%), followed by vancomycin (75.7%) and linezolid (70.3%). Also, most of these isolates (73%) could form biofilms. For example, 18.9% of Enterococcus strains formed strong biofilm, whereas 32.4% of isolates formed moderate biofilm and 21.6% of isolates formed weak biofilm. The most prevalent resistance genes found in our isolates were blaZ (54%), vanA (40%), ermB (51.4%), tetM (13.5%) and optrA (10.8%). Moreover, asa1 (37.8%), cylA (42.3%), gelE (78.4%), esp (32.4%), EF3314(48.6%) and ace (75.5%) were the most common virulence genes. A significant correlation was found between biofilm formation, multidrug resistance and virulence genes of the isolates. This study highlights several aspects of virulence and harmfulness of Enterococcus strains isolated from subclinical mastitic milk, which necessitates continuous inspection and monitoring of dairy animals.


2021 ◽  
Vol 8 (Supplement_1) ◽  
pp. S631-S631
Author(s):  
Jose Enrique Fernandez ◽  
Robert L Williams ◽  
Vasna Carr ◽  
Renae Miller

Abstract Background Development of a tebipenem antimicrobial susceptibility test was completed for the MicroScan Dried Gram-negative MIC (MSDGN) Panel when compared to CLSI broth microdilution reference panels. Methods Development was conducted by comparing MICs obtained using the MSDGN panel to MICs using a CLSI broth microdilution reference panel. A total of 669 Enterobacterales isolates were tested at 16, 18, and 20 hour incubation times using the turbidity and Prompt®* methods of inoculation. MSDGN panels were incubated at 35 ± 2ºC and read on the WalkAway System, the autoSCAN-4 instrument, and read visually. Frozen reference panels, prepared according to ISO/CLSI methodology, were inoculated using the turbidity inoculation method. All frozen reference panels were incubated at 35 ± 2ºC and read visually. Dilution sequence evaluated is 0.03-32 µg/mL. Results When compared to frozen reference panel results, essential agreement for all isolates tested during development are as follows: Conclusion The development data showed that tebipenem MIC results for Enterobacterales obtained with the MSDGN panel correlate well with MICs obtained using frozen reference panels. Essential agreement is > 90% for all inoculation and read methods. For Investigational Use Only. The performance characteristics of this product have not been established. * Prompt® is a registered trademark of 3M Company, St. Paul, MN USA. © 2021 Beckman Coulter. All rights reserved. Beckman Coulter, the stylized logo, and the Beckman Coulter product and service marks mentioned herein are trademarks or registered trademarks of Beckman Coulter, Inc. in the United States and other countries. Disclosures Jose Enrique Fernandez, n/a, Beckman Coulter (Employee) Vasna Carr, n/a, Beckman Coulter (Employee) Renae Miller, n/a, Beckman Coulter (Employee)


F1000Research ◽  
2021 ◽  
Vol 10 ◽  
pp. 1093
Author(s):  
Pablo Alejandro Millones Gómez ◽  
Lidia Yileng Tay Chu Jon ◽  
Dora Jesús Maurtua Torres ◽  
Reyma Evelyn Bacilio Amaranto ◽  
Ingrit Elida Collantes Díaz ◽  
...  

Background: Natural products with antibacterial potential have begun to be tested on biofilm models, bringing us closer to understanding the response generated by the complex microbial ecosystems of the oral cavity. The objective of this study was to evaluate the antibacterial, antibiofilm, and cytotoxic activities and chemical compositions of Peruvian propolis in an in vitro biofilm of Streptococcus gordonii and Fusobacterium nucleatum. Methods: The experimental work involved a consecutive, in vitro, longitudinal, and double-blinded study design. Propolis samples were collected from 13 different regions of the Peruvian Andes. The disk diffusion method was used for the antimicrobial susceptibility test. The cytotoxic effect of propolis on human gingival fibroblasts was determined by cell viability method using the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay, and the effect of propolis on the biofilm was evaluated by confocal microscopy and polymerase chain reaction (PCR). Results: The 0.78 mg/mL and 1.563 mg/mL concentrations of the methanolic fraction of the chloroform residue of Oxapampa propolis showed effects on biofilm thickness and the copy numbers of the srtA gene of S. gordonii and the radD gene of F. nucleatum at 48 and 120 hours, and chromatography (UV, λ 280 nm) identified rhamnocitrin, isorhamnetin, apigenin, kaempferol, diosmetin, acacetin, glycerol, and chrysoeriol. Conclusions: Of the 13 propolis evaluated, it was found that only the methanolic fraction of Oxapampa propolis showed antibacterial and antibiofilm effects without causing damage to human gingival fibroblasts. Likewise, when evaluating the chemical composition of this fraction, eight flavonoids were identified.


2021 ◽  
Author(s):  
Mehdi Bakht ◽  
Safar Ali Alizadeh ◽  
Sara Rahimi ◽  
Raana Kazemzade anari ◽  
Mohammad Rostamani ◽  
...  

Abstract Background: One of the most important reasons for human mortality worldwide is Hospital-acquired infections, which can be controlled by efficient use of proper disinfectants for the Hospital settings. The main aim of the present survey was to assess the susceptibility of Pseudomonas aeruginosa producing and non-producing biofilm isolated to the five commonly used Hospital disinfectants, and evaluation of the synergistic effect of selective disinfectants and Ethylene-diamine-tetra acetic acid (EDTA), and the effect of exposure to sub-inhibitory concentrations of Sodium hypochlorite on antimicrobial susceptibility test.Results: The results showed that Sodium hypochlorite 5%, and Ethanol 70% is the most and less potent disinfectants against Pseudomonas aeruginosa, respectively. Clearly, the addition of EDTA increased the efficacy of selected disinfectants significantly. The changes in the antibiotic-resistance profiles after exposure to sub-inhibitory concentrations of disinfectants were observed for different classes of antibiotics. As well as near the all isolates harbored efflux pump genes and produced biofilm. Conclusion: For disinfection of Hospital surfaces and instruments, the mixture of disinfectant and EDTA were the most suitable selection in this study. In our study, it was clear that exposure to sub-inhibitory concentrations of disinfectants results in resistance to antibiotics. Also, strong and intermediate biofilm formers belonged to MDR/XDR strains.


2021 ◽  
Vol 2021 ◽  
pp. 1-6
Author(s):  
Letebrhan Yimesgen W. Grima ◽  
Shubisa Abera Leliso ◽  
Abebe Olani Bulto ◽  
Debebe Ashenafi

A cross-sectional study was carried out in and around Sebeta town dairy farms, Finfinne special zone, Ethiopia, from December 2019 to May 2020 to isolate, identify, and test antimicrobial susceptibility profile of Staphylococcus aureus from clinical mastitis. A total of 116 milk samples were purposively collected from 57 lactating cows with clinical mastitis. Isolation and identification of Staphylococcus aureus were carried out by using primary and secondary biochemical tests. Besides, Biolog was used for microbial identification systems. To know if the isolates develop resistance to antibiotics, the antimicrobial susceptibility test (ATS) was performed on Mueller-Hinton agar by the disk diffusion method. From a total of 57 lactating cows and 116 teat quarters examined, 21.05% (12/57) and 15.52% (18/116) were positive for S. aureus from clinical mastitis, respectively. From a total of 116 milk samples collected, 15.52% (18/116) Staphylococcus aureus were isolated, and from 11 farms surveyed, about 72.72% (8/11) overall farm prevalence of clinical mastitis due to S. aureus was recorded. All the 18 Staphylococcus aureus isolates were found susceptible to sulphamethoxazole/trimethoprim, erythromycin, gentamicin, ciprofloxacin, and chloramphenicol. However, high level of resistance was observed to common drugs such as penicillin (88.89%, 16/18) and tetracycline (61.11%, 11/18). The observed high level of resistance to penicillin and tetracycline also indicates the need to visit our treatment guidelines for mastitis caused by Staphylococcus aureus. Therefore, improved management and early treatment of the cases with drug of choice after the antimicrobial susceptibility test for each specific case can reduce chance of further development of resistance and are imperative to tackle clinical mastitis occurring at Sebeta and other similar farms in Ethiopia.


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