scholarly journals Widespread Occurrence of Possible Antibiotic Efflux Mechanism in Multidrug Resistant Intestinal E. coli Strains Isolated from Healthy Human Subjects in Bangladesh

2016 ◽  
Vol 30 (1-2) ◽  
pp. 55-59
Author(s):  
M Hasibur Rahman ◽  
Jamil Mahmud ◽  
Md Mahamudul Haque ◽  
Farzana Tarannum Tuli ◽  
Nazneen Jahan ◽  
...  
Keyword(s):  
Ethidium Bromide ◽  
Efflux Pump ◽  
Human Subjects ◽  
Agar Plate ◽  
Multidrug Resistant ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Healthy Human ◽  
Efflux Mechanism ◽  
High Level

A total of 50 isolates of Escherichia coli obtained from healthy adult human subjects were studied and tested for possible presence of efflux mechanism in resistance determination and possible correlation of plasmids with resistance.Minimal inhibitory concentration (MIC) of the antibiotics amoxicillin, azithromycin, ciprofloxacin, chloramphenicol and tetracycline were determined by agar dilution method with or without the H+/K+ proton pump inhibitor omeprazole. Plasmids were extracted by rapid alkaline plasmid extraction method and analyzed by agarose gel electrophoresis. Many strains showed 5 – 10 fold reduction of MIC values in the presence of omeprazole; a few strains showed up to 100-fold MIC reduction. Plasmid analysis of these 50 isolates revealed the presence of both plasmidless and plasmid containing strains, the latter with plasmid number varying from one to seven. However, the plasmids apparently had no relationship with high level antibiotic tolerance as indicated by the observation that some plasmidless strains had very high MIC values, while other strains containing several plasmids had very low MIC. Decrease in MIC in the presence of omeprazole apparently indicates existence of an efflux mechanism. Evidence of the efflux of ethidium bromide was noted in some strains that had been grown in ethidium bromide containing agar plate with and without omeprazole. These results suggest that reduction of MIC caused by omeprazole may be related to possible inhibition of efflux pump activity by omeprazole in the isolates studied.Bangladesh J Microbiol, Volume 30, Number 1-2,June-Dec 2013, pp 55-59

scholarly journals Prevalence of a Putative Efflux Mechanism among Fluoroquinolone-Resistant Clinical Isolates ofStreptococcus pneumoniae

1998 ◽  
Vol 42 (8) ◽  
pp. 2032-2035 ◽  
Author(s):  
Nigel P. Brenwald ◽  
Martin J. Gill ◽  
Richard Wise
Keyword(s):  
Ethidium Bromide ◽  
Efflux Pump ◽  
Clinical Isolates ◽  
Fluoroquinolone Resistance ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
The United Kingdom ◽  
Agar Dilution ◽  
Efflux Mechanism ◽  
Clinically Significant

ABSTRACT Twenty-three norfloxacin-selected first-step mutants ofStreptococcus pneumoniae showed low-level fluoroquinolone resistance. Their susceptibility to norfloxacin in the presence or absence of reserpine and known efflux pump substrates was determined by an agar dilution method. Five mutants showed four- to eightfold increases in their susceptibility to norfloxacin in the presence of reserpine and four- to eightfold decreases in their susceptibility to acriflavine and ethidium bromide. This phenotype is suggestive of an efflux mechanism of resistance. A representative of these mutants, 1N27, accumulated significantly less ethidium bromide than the parent strain; reserpine abolished these differences. No changes in the quinolone resistance-determining regions of parC,parE, gyrA, or gyrB were found in this mutant. By our validated agar dilution method, the efflux phenotype was sought in clinical isolates of S. pneumoniae. Of 1,037 clinical isolates examined from the United Kingdom, 273 showed reduced susceptibility to norfloxacin or ciprofloxacin. Of these, 45.4% showed the efflux phenotype. Our findings suggest that an efflux mechanism may be a frequent cause of clinically significant fluoroquinolone resistance in pneumococci.

scholarly journals Triclosan resistance in clinical isolates of Acinetobacter baumannii

2009 ◽  
Vol 58 (8) ◽  
pp. 1086-1091 ◽  
Author(s):  
Yagang Chen ◽  
Borui Pi ◽  
Hua Zhou ◽  
Yunsong Yu ◽  
Lanjuan Li
Keyword(s):  
Acinetobacter Baumannii ◽  
Efflux Pump ◽  
Resistance Mechanism ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Active Efflux ◽  
Low Level ◽  
High Level ◽  
Resistance Rates ◽  
Triclosan Resistance

The susceptibility to triclosan of 732 clinical Acinetobacter baumannii isolates obtained from 25 hospitals in 16 cities in China from December 2004 to December 2005 was screened by using an agar dilution method. Triclosan MICs ranged between 0.015 and 16 mg l−1, and the MIC90 was 0.5 mg l−1, lower than the actual in-use concentration of triclosan. Twenty triclosan-resistant isolates (MICs ≥1 mg l−1) were characterized by antibiotic susceptibility, clonal relatedness, fabI mutation, fabI expression, and efflux pump phenotype and expression to elucidate the resistance mechanism of A. baumannii to triclosan. The resistance rates of triclosan-resistant isolates to imipenem, levofloxacin, amikacin and tetracycline were higher than those of triclosan-sensitive isolates. Triclosan resistance was artificially classified as low level (MICs 1–2 mg l−1) or high level (MICs ≥4 mg l−1). High-level triclosan resistance could be explained by a Gly95Ser mutation of FabI, whilst wild-type fabI was observed to be overexpressed in low-level resistant isolates. Active efflux did not appear to be a major reason for acquired triclosan resistance, but acquisition of resistance appeared to be dependent on a background of intrinsic triclosan efflux.

scholarly journals Prevalence and characterization of extended spectrum beta-lactamase-producing Enterobacter cloacae strains in Algeria

2013 ◽  
Vol 7 (11) ◽  
pp. 804-811 ◽  
Author(s):  
Sabrina Nedjai ◽  
Abouddihaj Barguigua ◽  
Nassima Djahmi ◽  
Loubna Jamali ◽  
Khalid Zerouali ◽  
...  
Keyword(s):  
Enterobacter Cloacae ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Extended Spectrum Beta Lactamase ◽  
Agar Dilution ◽  
Synergy Test ◽  
High Level ◽  
Genomic Typing ◽  
Microbiological Data

Introduction: Expended spectrum β-lactamase (ESBL)-producing Enterobacter cloacae is an important nosocomial pathogen. In this study, the prevalence and the molecular epidemiology of ESBL producing E. cloacae strains isolated from various hospitals in Annaba, Algeria were investigated. Methodology: The study involved 63 isolates of E. cloacae obtained during 2009 at the four hospitals in Annaba. The detection of ESBL was performed using the double-disk synergy test and the combined disk test. Minimum inhibitory concentrations (MICs) were determined using the agar dilution method. The presence of blaCTX-M, blaSHV, blaTEM, and blaDHA β-lactamase genes was evaluated by PCR, and genomic typing was determined by pulsed-field gel electrophoresis (PFGE) analysis. The clinical and microbiological data were entered into the EpiI Info database. Results: Thirty isolates (47.6%) had an ESBL phenotype. BlaCTX-M group1 (76%); blaTEM (70%) were the most prevalent, followed by blaDHA (16.6%) and blaSHV (10%). Eighteen strains expressed at least two bla genes. MICs revealed a high level of resistance to cefotaxime, ceftazidime, and cefepime.  PFGE revealed an epidemic clonal dissemination of these isolates. Various risk factors associated with the occurrence of ESBL-producing E. cloacae were detected. Conclusions: A higher frequency of ESBL-producing isolates and a diversity of β-lactamases were detected among ESBL-producing E. cloacae; these resulted from an epidemic clonal dissemination and high transference of ESBL genes between bacteria in hospital settings. Strict measures will be required to control the further spread of these pathogens in hospital settings.

scholarly journals Detection of OXA-181/OXA-48 carbapenemase producing Enterobacteriaceae in Bangladesh

2016 ◽  
Vol 9 (2) ◽  
pp. 45-51 ◽  
Author(s):  
Rehana Khatun ◽  
SM Shamsuzzaman
Keyword(s):  
Health Concern ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
College Hospital ◽  
Medical College ◽  
Epidemiological Monitoring ◽  
Diffusion Technique ◽  
Genes Encoding ◽  
High Level ◽  
Phenotypic Tests

Carbapenem resistant Enterobacteriaceae (CRE) is becoming a major public health concern globally. Detection of carbapenem hydrolyzing enzyme carbapenemase in Enterobacteriaceae is important to institute appropriate therapy and to initiate preventive measures. This study was designed to determine the presence of carbapenemase producers among the CRE isolated from patients at Dhaka Medical College Hospital, Bangladesh. Twenty-nine CRE strains detected by disk diffusion technique were included in the study. Minimum inhibitory concentration of imipenem and tigecycline was determined by agar dilution method. Carbapenemase production was phenotypically detected by Modified Hodge test while MBL producers were detected by combined disk and double disk synergy tests. Genes encoding blaNDM-1, blaOXA-181, blaOXA-48, blaKPC, blaCTX-M-15, blaOXA-1-group were identified by polymerase chain reaction (PCR). Out of 29 CRE, nineteen (65.6%) were positive for carbapenemase by any of the three phenotypic tests namely MHT, CD or DD tests. Those 19 isolates were also positive either for blaNDM-1 or blaOXA-181/blaOXA-48 by PCR. Of the 19 PCR positive isolates, the rate of positivity for blaNDM- 1, blaOXA-181/blaOXA-48 and blaNDM-1+ blaOXA-181/blaOXA-48 was 73.7% (14/19), 57.9% (11/19) and 31.6% (6/19) respectively. Both blaOXA-181 and blaOXA-48 co-existed. All the carbapenemase producing organisms harboured blaCTX-M-15 except one C. freundii strain. The rate of resistance to different classes of antibiotics ranged from 63.2% to 100% except colistin and tigecycline. Organisms positive for OXA-181/OXA-48 had a low level of resistance to carbapenem (MIC 1 - 4 ì g/ml) while with NDM-1 had high level resistance to imipenem (MICs 16 - ? 32 ì g/ ml). Out of 19 carbapenemase positive isolates, 12 (63.16%) were extensively drug-resistant (XDR) and were only sensitive to tigecycline and colistin. The result of this study showed the presence of blaOXA-181/ blaOXA-48, blaNDM-1 positive strains in Bangladesh and colistin and tigecycline were the most effective drugs against carbapenemase producing Enterobacteriaceae (CPE). Epidemiological monitoring of carbapenemase producing organisms in Bangladesh is important to prevent their dissemination.Ibrahim Med. Coll. J. 2015; 9(2): 45-51

scholarly journals Ethidium Bromide MIC Screening for Enhanced Efflux Pump Gene Expression or Efflux Activity in Staphylococcus aureus

2010 ◽  
Vol 54 (12) ◽  
pp. 5070-5073 ◽  
Author(s):  
Diixa Patel ◽  
Christos Kosmidis ◽  
Susan M. Seo ◽  
Glenn W. Kaatz
Keyword(s):  
Staphylococcus Aureus ◽  
Ethidium Bromide ◽  
Efflux Pump ◽  
Large Strain ◽  
Efflux Pumps ◽  
Multidrug Resistant ◽  
Reverse Transcription Pcr ◽  
Biocide Resistance ◽  
Straightforward Method ◽  
Short Period

ABSTRACT Multidrug resistance efflux pumps contribute to antimicrobial and biocide resistance in Staphylococcus aureus. The detection of strains capable of efflux is time-consuming and labor-intensive using currently available techniques. A simple and inexpensive method to identify such strains is needed. Ethidium bromide is a substrate for all but one of the characterized S. aureus multidrug-resistant (MDR) efflux pumps (NorC), leading us to examine the utility of simple broth microtiter MIC determinations using this compound in identifying efflux-proficient strains. Quantitative reverse transcription-PCR identified the increased expression of one or more MDR efflux pump genes in 151/309 clinical strains (49%). Ethidium bromide MIC testing was insensitive (48%) but specific (92%) in identifying strains with gene overexpression, but it was highly sensitive (95%) and specific (99%) in identifying strains capable of ethidium efflux. The increased expression of norA with or without other genes was most commonly associated with efflux, and in the majority of cases that efflux was inhibited by reserpine. Ethidium bromide MIC testing is a simple and straightforward method to identify effluxing strains and can provide accurate predictions of efflux prevalence in large strain sets in a short period of time.

scholarly journals Potential spread of multidrug-resistant coagulase-negative staphylococci through healthcare waste

2015 ◽  
Vol 9 (01) ◽  
pp. 029-034 ◽  
Author(s):  
Thiago César Nascimento ◽  
Vânia Lúcia Da Silva ◽  
Alessandra Barbosa Ferreira-Machado ◽  
Cláudio Galuppo Diniz
Keyword(s):  
Meca Gene ◽  
Multidrug Resistant ◽  
Resistant Bacteria ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Coagulase Negative Staphylococcus ◽  
Coagulase Negative Staphylococci ◽  
Healthcare Waste ◽  
Sanitary Landfills ◽  
Rdna Sequencing

Introduction: Healthcare waste (HCW) might potentially harbor infective viable microorganisms in sanitary landfills. We investigated the antimicrobial susceptibility patterns and the occurrence of the mecA gene in coagulase-negative Staphylococcus strains (CoNS) recovered from the leachate of the HCW in an untreated sanitary landfill. Methodology: Bacterial identification was performed by physiological and molecular approaches, and minimum inhibitory concentrations (MICs) of antimicrobial drugs were determined by the agar dilution method according to CLSI guidelines. All oxacillin-resistant bacteria were screened for the mecA gene. Results: Out of 73 CoNS, seven different species were identified by 16S rDNA sequencing: Staphylococcus felis (64.4%; n = 47), Staphylococcus sciuri (26.0%; n = 19), Staphylococcus epidermidis (2.7%; n = 2), Staphylococcus warneri (2.7%; n = 2), Staphylococcus lentus (1.4%; n = 1), Staphylococcus saprophyticus (1.4%; n = 1), and Staphylococcus haemolyticus (1.4%; n = 1). Penicillin was the least effective antimicrobial (60.3% of resistance; n = 44) followed by erythromycin (39.8%; n = 29), azithromycin (28.8%; n = 21), and oxacillin (16.5%; n = 12). The most effective drug was vancomycin, for which no resistance was observed, followed by gentamicin and levofloxacin, for which only intermediate resistance was observed (22%, n = 16 and 1.4%, n = 1, respectively). Among the oxacillin-resistant strains, the mecA gene was detected in two isolates. Conclusions: Considering the high antimicrobial resistance observed, our results raise concerns about the survival of putative bacterial pathogens carrying important resistance markers in HCW and their environmental spread through untreated residues discharged in sanitary landfills.

scholarly journals Antimicrobial resistance of Enterococcus faecium and Enterococcus faecalis, isolated from blood culture of patients with hematological malignancies during different study periods

2021 ◽  
Vol 16 (1) ◽  
pp. 54-63
Author(s):  
A. V. Fedorova ◽  
G. A. Klyasova ◽  
I. N. Frolova ◽  
S. A. Khrulnova ◽  
A. V. Vetokhina ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Blood Culture ◽  
Enterococcus Faecalis ◽  
Enterococcus Faecium ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
High Susceptibility ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
High Level

Objective: to determine antimicrobial resistance of Enterococcus faecium and Enterococcus faecalis isolated from blood culture of hematological patients during different study periods.Materials and methods. Antimicrobial susceptibility of Enterococcus spp., collected as part of the multicenter study was tested by the broth microdilution method (USA Clinical and Laboratory Standards Institute (CLSI), 2018), to daptomycin by Etest (bioMeriéux, France). High-level gentamicin resistance (HLGR) and high-level streptomycin resistance (HLSR) was performed by the agar dilution method (CLSI (Oxoid, UK), 2018).Results. The susceptibility of 366 E. faecium (157 in 2002-2009 and 209 in 2010-2017) and 86 E. faecalis (44 in 20022009 and 42 in 2010-2017) was studied. In the second study period (2010-2017) the rise of vancomycin-resistant E. faecium (VREF) increased from 8.3 % to 23.4 % (p = 0.0001), and two linezolid-resistant (LREF) were identified. All VREF and LREF remained susceptible to daptomycin and tigecycline. The rate of susceptible to tetracycline E. faecium remained the same (73.9 and 74.6 %), and an increase in susceptibility to chloramphenicol (74.5 and 82.3 %) was observed. Susceptibility of E. faecium to tetracycline was detected with almost the same rate and in a part of isolates, the increase of susceptibility to chloramphenicol was registered during the analyzed periods. The rise of E. faecium susceptible to HLGR and HLSR has increased significantly in 2010-2017 compared to 2002-2009. Erythromycin, levofloxacin, ampicillin and penicillin had the least activity against E. faecium (less than 5 %).All E. faecalis were susceptible to tigecycline, linezolid, and teicoplanin. Only one of E. faecalis had intermediate resistance to vancomycin. High susceptibility to ampicillin in E. faecalis remained unchanged (97.7 and 97.6 %, respectively). In the second period of the study the rise of susceptible E. faecalis decreased significantly to penicillin (from 97.7 % to 76.2 %), to levofloxacin (from 59.1 % to 31 %), to HLSR (from 52.3 % до 31 %), and to HLGR (from 47.7 % to 26.2 %), remained unchanged to chloramphenicol (52.3 % and 50 %) and was minimal to erythromycin and tetracycline.Conclusion. The study demonstrated higher rates of antibiotic resistance among E. faecium, which consisted of an increase in VREF and the appearance of linezolid-resistant strains. High susceptibility to ampicillin remained in E. faecalis, but there was an increase in resistance to penicillin and aminoglycosides.

scholarly journals Farnesol abrogates biofilm- and efflux pump- associated genes in drug resistant Candida auris strains

2021 ◽  
Vol 3 (12) ◽  
Author(s):  
Vartika Srivastava ◽  
Aijaz Ahmad
Keyword(s):  
Active Drug ◽  
Efflux Pump ◽  
Antifungal Susceptibility ◽  
Efflux Pumps ◽  
Multidrug Resistant ◽  
Major Facilitator Superfamily ◽  
Drug Efflux ◽  
Candida Auris ◽  
Efflux Mechanism ◽  
Major Facilitator

Background: Candida auris, a decade old Candida species, has been identified globally as a significant nosocomial multidrug resistant (MDR) pathogen responsible for causing invasive outbreaks. Biofilms and over expression of efflux pumps such as Major Facilitator Superfamily and ATP Binding Cassette are known to cause multidrug resistance in Candida species, including C. auris. Therefore, targeting these factors may prove an effective approach to combat MDR in C. auris. Methods: In this study, 25 clinical isolates of C. auris from different hospitals of South Africa were used. Antifungal susceptibility profile of all the isolates against commonly used drugs was determined following CLSI recommended guidelines. Rhodamine-6-G extracellular efflux and intracellular accumulation assays were used to study active drug efflux mechanism. We further studied the role of farnesol in modulating development of biofilms and drug efflux in C. auris. Down-regulation of biofilm- and efflux pump- associated genes by farnesol was also investigated. CLSM analysis for examining C. auris biofilm architecture among treated and untreated isolates. Results: Most of the isolates (twenty-two) were found resistant to FLZ whereas five were resistant to AmB. All the isolates were found capable of biofilm formation and ornamented with active drug efflux mechanism. The MIC for planktonic cells ranged from 62.5-125 mM and for sessile cells was 125 mM (0 h and 4 h biofilm) and 500 mM (12 h and 24 h biofilm), CLSM studies also confirmed these findings. Farnesol also blocked efflux pumps and down-regulated biofilm- and efflux pump- associated genes. Conclusion: Modulation of biofilm- and efflux pump- associated genes by farnesol represent a promising approach in combating C. auris infection.

scholarly journals In vitro efficacy of synergistic antibiotic combinations in imipenem resistant Pseudomonas aeruginosa strains

2017 ◽  
Vol 9 (1) ◽  
pp. 3-8
Author(s):  
Aleya Farzana ◽  
S. M. Shamsuzzaman
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Carbapenem Resistance ◽  
Multidrug Resistant ◽  
Diffusion Method ◽  
Considerable Proportion ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Disk Diffusion Method ◽  
New Antibiotics

The increase in antibiotic resistance coincided with the decline in production of new antibiotics. Combination antibiotic treatment is preferred in nosocomial infections caused by multidrug resistant Pseudomonas aeruginosa. In vitro synergism test by agar dilution method were used to choose the combinations which might be used in clinic. The aim of this study was to investigate the synergistic efficacy of antibiotic combinations in imipenem resistant P. aeruginosa strains. Carbapenem resistance (imipenem and meropenem) wasdetermined by disk diffusion method. Among isolated P. aeruginosa 44.9% were cabapenem resistant. The MIC of drugs among 25 imipenem resistant isolates ranged from >_ 256 mg/L to <_ 8 mg/L for imipenem, >_ 1024 mg/L to <_ 64 mg/L for ceftriaxone, >_ 256 mg/L to <_ 8 mg/L for amikacin, >_ 16 mg/L to <_ 2 mg/L for colistin, >_ 512 mg/L to <_ 16 mg/L for piperacillin/tazobactam. Among antibiotic combinations, piperacillin /tazobactam- amikacin was most effective with 80% synergism next to which was imipenem-amikacin with 60% synergism, then imipenem-colistin with 50% synergism, imipenem-ceftriaxone with 30% synergism. Only one combination (piperacillin/tazobactum -imipenem showed 20% antagonism. All these combinations had considerable proportion of additive effect which is also desirable for these multi drug resistant isolates.Bangladesh J Med Microbiol 2015; 9 (1): 3-8

scholarly journals Community Acquired Enterococcal Urinary Tract Infections and Antibiotic Resistance Profile in North India

2016 ◽  
Vol 8 (01) ◽  
pp. 050-054 ◽  
Author(s):  
Varun Goel ◽  
Dinesh Kumar ◽  
Rajendra Kumar ◽  
Purva Mathur ◽  
Sarman Singh
Keyword(s):  
Urinary Tract ◽  
Urinary Tract Infections ◽  
Tertiary Care Hospital ◽  
Tertiary Care ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Care Hospital ◽  
Agar Dilution ◽  
High Level ◽  
Tract Infections

ABSTRACT Background: Urinary tract infections (UTIs) remain a major problem both in hospitalized and outdoor patients. Multidrug-resistant enterococci are emerging as a major nosocomial pathogen with increasing frequency. However, the incidence of community-acquired enterococcal infections and species prevalent in India is not thoroughly investigated. Objectives: This study aims to estimate the burden of community-acquired UTIs seen at a tertiary care hospital and to identify the Enterococcus species isolated from these patients. The study also aims to determine the antibiotic susceptibility pattern with reference to high-level aminoglycosides and vancomycin. Materials and Methods: Semi-quantitative cultures from a total of 22,810 urine samples obtained from patients seen at various Outpatient Departments were analyzed. From them 115 nonduplicate isolates of enterococci were obtained as significant pure growth (>105 cfu/ml) and speciated. Antibiotic susceptibility was performed by Kirby–Bauer disc diffusion method. Vancomycin resistance screening was performed by the vancomycin screen agar method recommended by Clinical and Laboratory Standards Institute and confirmed by determination of minimum inhibitory concentration by agar dilution method. Results: Of 115 enterococcal isolates, 61 were identified as Enterococcus faecalis, 42 as Enterococcus faecium, 3 each as Enterococcus dispar, and Enterococcus pseudoavium. High-level gentamicin resistance (HLGR) was higher in E. faecium (47.6%) than E. faecalis (32.7%) and HLSR also showed the same pattern with 47.6% and 27.9% resistance, respectively. Vancomycin resistant enterococci accounted for 11.3% of the isolates, and out of them 53.8% were E. faecium by agar dilution method. Conclusion: High rate of resistance to antibiotics of penicillin group and aminoglycosides was observed in our tertiary care hospital even in community acquired UTIs. Hence, there is an urgent need for more rational and restricted use of antimicrobials.

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