scholarly journals Antimicrobial susceptibility patterns of Brazilian Haemophilus parasuis field isolates

2017 ◽  
Vol 37 (11) ◽  
pp. 1187-1192 ◽  
Author(s):  
Michela Miani ◽  
Monique S. Lorenson ◽  
João A. Guizzo ◽  
Julia P. Espíndola ◽  
Elías F. Rodríguez-Ferri ◽  
...  
Keyword(s):  
Antimicrobial Agents ◽  
Clinical Isolates ◽  
Haemophilus Parasuis ◽  
Swine Industry ◽  
Antimicrobial Drugs ◽  
Field Isolates ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Indirect Hemagglutination ◽  
Susceptibility Patterns

ABSTRACT: Haemophilus parasuis is the etiological agent of Glässer’s disease (GD), an ubiquitous infection of swine characterized by systemic fibrinous polyserositis, polyarthritis and meningitis. Intensive use of antimicrobial agents in swine husbandries during the last years triggered the development of antibiotic resistances in bacterial pathogens. Thus, regular susceptibility testing is crucial to ensure efficacy of different antimicrobial agents to this porcine pathogen. In this study, 50 clinical isolates from South Brazilian pig herds were characterized and analyzed for their susceptibility to commonly used antibiotic. The identification and typing of clinical isolates was carried out by a modified indirect hemagglutination assay combined with a multiplex PCR. The susceptibility of each isolate was analyzed by broth microdilution method against a panel of 21 antimicrobial compounds. We found that field isolates are highly resistance to gentamycin, bacitracin, lincomycin and tiamulin, but sensitive to ampicillin, clindamycin, neomycin, penicillin, danofloxacin and enrofloxacin. Furthermore, an individual susceptibility analysis indicated that enrofloxacin is effective to treat clinical isolates with the exception of those classified as serovar 1. The results presented here firstly demonstrate the susceptibility of Brazilian clinical isolates of H. parasuis to antimicrobials widely used by swine veterinary practitioners and strengthen the need to perform susceptibility test prior to antibiotic therapy during GD outbreaks. In addition, because only six antimicrobial drugs (28.6%) were found effective against field isolates, a continuous surveillance of the susceptibility profile should be of major concern to the swine industry.

scholarly journals Prevalence of Antimicrobial Resistance among Clinical Isolates of Bacteroides fragilis Group in Canada in 2010-2011: CANWARD Surveillance Study

2011 ◽  
Vol 56 (3) ◽  
pp. 1247-1252 ◽  
Author(s):  
James A. Karlowsky ◽  
Andrew J. Walkty ◽  
Heather J. Adam ◽  
Melanie R. Baxter ◽  
Daryl J. Hoban ◽  
...  
Keyword(s):  
Antimicrobial Agents ◽  
Bacteroides Fragilis ◽  
Clinical Isolates ◽  
Surveillance Study ◽  
Content Type ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Amoxicillin Clavulanate ◽  
Bacteroides Fragilis Group ◽  
Bacteroides Ovatus

ABSTRACTClinical isolates of theBacteroides fragilisgroup (n= 387) were collected from patients attending nine Canadian hospitals in 2010-2011 and tested for susceptibility to 10 antimicrobial agents using the Clinical and Laboratory Standards Institute (CLSI) broth microdilution method.B. fragilis(59.9%),Bacteroides ovatus(16.3%), andBacteroides thetaiotaomicron(12.7%) accounted for ∼90% of isolates collected. Overall rates of percent susceptibility were as follows: 99.7%, metronidazole; 99.5%, piperacillin-tazobactam; 99.2%, imipenem; 97.7%, ertapenem; 92.0%, doripenem; 87.3%, amoxicillin-clavulanate; 80.9%, tigecycline; 65.9%, cefoxitin; 55.6%, moxifloxacin; and 52.2%, clindamycin. Percent susceptibility to cefoxitin, clindamycin, and moxifloxacin was lowest forB. thetaiotaomicron(n= 49, 24.5%),Parabacteroides distasonis/P. merdae(n= 11, 9.1%), andB. ovatus(n= 63, 31.8%), respectively. One isolate (B. thetaiotaomicron) was resistant to metronidazole, and two isolates (bothB. fragilis) were resistant to both piperacillin-tazobactam and imipenem. Since the last published surveillance study describing Canadian isolates ofB. fragilisgroup almost 20 years ago (A.-M. Bourgault et al., Antimicrob. Agents Chemother. 36:343–347, 1992), rates of resistance have increased for amoxicillin-clavulanate, from 0.8% (1992) to 6.2% (2010-2011), and for clindamycin, from 9% (1992) to 34.1% (2010-2011).

scholarly journals In Vitro Activity of Eravacycline against Gram-Positive Bacteria Isolated in Clinical Laboratories Worldwide from 2013 to 2017

2019 ◽  
Vol 64 (3) ◽  
Author(s):  
Ian Morrissey ◽  
Stephen Hawser ◽  
Sibylle H. Lob ◽  
James A. Karlowsky ◽  
Matteo Bassetti ◽  
...  
Keyword(s):  
Antimicrobial Agents ◽  
Clinical Isolates ◽  
Gram Positive ◽  
Content Type ◽  
Gram Positive Bacteria ◽  
Microdilution Method ◽  
Clinical Laboratories ◽  
Broth Microdilution Method ◽  
Doubling Dilution

ABSTRACT Eravacycline is a novel, fully synthetic fluorocycline antibiotic being developed for the treatment of serious infections, including those caused by resistant Gram-positive pathogens. Here, we evaluated the in vitro activities of eravacycline and comparator antimicrobial agents against a recent global collection of frequently encountered clinical isolates of Gram-positive bacteria. The CLSI broth microdilution method was used to determine in vitro MIC data for isolates of Enterococcus spp. (n = 2,807), Staphylococcus spp. (n = 4,331), and Streptococcus spp. (n = 3,373) isolated primarily from respiratory, intra-abdominal, urinary, and skin specimens by clinical laboratories in 37 countries on three continents from 2013 to 2017. Susceptibilities were interpreted using both CLSI and EUCAST breakpoints. There were no substantive differences (a >1-doubling-dilution increase or decrease) in eravacycline MIC90 values for different species/organism groups over time or by region. Eravacycline showed MIC50 and MIC90 results of 0.06 and 0.12 μg/ml, respectively, when tested against Staphylococcus aureus, regardless of methicillin susceptibility. The MIC90 values of eravacycline for Staphylococcus epidermidis and Staphylococcus haemolyticus were equal (0.5 μg/ml). The eravacycline MIC90s for Enterococcus faecalis and Enterococcus faecium were 0.06 μg/ml and were within 1 doubling dilution regardless of the vancomycin susceptibility profile. Eravacycline exhibited MIC90 results of ≤0.06 μg/ml when tested against Streptococcus pneumoniae and beta-hemolytic and viridans group streptococcal isolates. In this surveillance study, eravacycline demonstrated potent in vitro activity against frequently isolated clinical isolates of Gram-positive bacteria (Enterococcus, Staphylococcus, and Streptococcus spp.), including isolates collected over a 5-year period (2013 to 2017), underscoring its potential benefit in the treatment of infections caused by common Gram-positive pathogens.

scholarly journals Determination of CEM-101 Activity Tested against Clinical Isolates of Neisseria meningitidis from a Worldwide Collection

2010 ◽  
Vol 54 (9) ◽  
pp. 4009-4011 ◽  
Author(s):  
Douglas J. Biedenbach ◽  
Mariana Castanheira ◽  
Ronald N. Jones
Keyword(s):  
Neisseria Meningitidis ◽  
Meningococcal Disease ◽  
Antimicrobial Agents ◽  
Clinical Isolates ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Broth Microdilution Method

ABSTRACT The activity of CEM-101, a fluoroketolide, was compared to those of 11 other antimicrobial agents using the reference broth microdilution method tested against 103 Neisseria meningitidis strains, including ciprofloxacin-nonsusceptible isolates with confirmed gyr A (T91I) mutations. Among the tested isolates, 79.6% were serogroup B or C and all isolates were susceptible to ceftriaxone, azithromycin, minocycline, and rifampin. However, penicillin-nonsusceptible strains were observed (15.5%) and susceptibility to trimethoprim-sulfamethoxazole was only 50.5%. CEM-101 was the most active macrolide-like compound (MIC90, ≤0.015 μg/ml) compared with MIC90s of telithromycin (MIC90, 0.03 μg/ml), azithromycin and clarithromycin (MIC90, 0.12 μg/ml), and erythromycin (MIC90, 0.25 μg/ml). CEM-101 could provide a potent alternative for the prophylaxis of meningococcal disease.

In vitro activities of acetylmidecamycin and other antimicrobials against human macrolide-resistant Mycoplasma pneumoniae isolates

2020 ◽  
Vol 75 (6) ◽  
pp. 1513-1517 ◽  
Author(s):  
Na Wang ◽  
Yunheng Zhou ◽  
Hong Zhang ◽  
Yang Liu
Keyword(s):  
Mycoplasma Pneumoniae ◽  
Antimicrobial Agents ◽  
Mycoplasma Hominis ◽  
Clinical Isolates ◽  
Mycoplasma Species ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Ureaplasma Spp

Abstract Objectives To assess the in vitro activities of acetylmidecamycin, a 16-membered macrolide, and 11 other antimicrobial agents against human mycoplasmas. Methods A total of 187 clinical isolates, Mycoplasma pneumoniae (n = 110), Mycoplasma hominis (n = 26) and Ureaplasma species (n = 51), were included in this study. The MICs of 12 antimicrobial agents, including acetylmidecamycin, thiamphenicol, chloramphenicol and some other macrolides, fluoroquinolones and tetracyclines, for these clinical isolates were determined by the broth microdilution method. Results For M. pneumoniae, the MIC90 values of the tested macrolides were: acetylmidecamycin (1 mg/L)<josamycin (4 mg/L)<midecamycin (8 mg/L)<azithromycin (16 mg/L)<erythromycin (>128 mg/L). Thiamphenicol and chloramphenicol had the same MIC90 (2 mg/L). For Ureaplasma species, the MIC90 values were: acetylmidecamycin (0.25 mg/L)<josamycin (0.5 mg/L)=midecamycin<azithromycin (1 mg/L)=erythromycin. Chloramphenicol had a lower MIC90 (2 mg/L) than that of thiamphenicol (4 mg/L). For M. hominis, the MIC90 values were: acetylmidecamycin (0.25 mg/L)<josamycin (0.5 mg/L)<midecamycin (2 mg/L)<azithromycin (>128 mg/L)=erythromycin. The MIC90 values of chloramphenicol and thiamphenicol were 2 and 4 mg/L, respectively. Conclusions The results indicated that acetylmidecamycin and thiamphenicol are active in vitro against the most common mycoplasma species infecting humans, including those resistant to macrolides and fluoroquinolones. Acetylmidecamycin and thiamphenicol might be a promising option for clinicians to treat infections caused by Mycoplasma and Ureaplasma spp., particularly macrolide-resistant M. pneumoniae in paediatrics and fluoroquinolone-resistant M. hominis in adults. Further investigation of their clinical roles in treating infections caused by these organisms is warranted.

scholarly journals In Vitro Antimicrobial Susceptibilities of Francisella tularensis subsp. holarctica Isolates from Tularemia Outbreaks That Occurred from the End of the 20th Century to the 2020s in Spain

Antibiotics ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 938
Author(s):  
Sonia Martínez-Martínez ◽  
Elías-Fernando Rodríguez-Ferri ◽  
David Rodríguez-Lázaro ◽  
Marta Hernández ◽  
José-Ignacio Gómez-Campillo ◽  
...  
Keyword(s):  
20Th Century ◽  
Francisella Tularensis ◽  
Antimicrobial Agents ◽  
Clinical Isolates ◽  
Tularensis Subsp ◽  
Microdilution Method ◽  
Castilla Y Leon ◽  
Broth Microdilution Method ◽  
Northwestern Spain

A collection of 177 Francisella tularensis subsp. holarctica clinical isolates (29 from humans and 148 from animals, mainly hares and voles) was gathered from diverse tularemia outbreaks in the Castilla y León region (northwestern Spain) that occurred from the end of the 20th century to the 2020s. Along with four F. tularensis subsp. holarctica reference strains, all of these clinical isolates were tested using a broth microdilution method to determine their susceptibility to 22 antimicrobial agents, including β-lactams, aminoglycosides and one member each of the tetracycline, glycylcycline, quinolone and sulphonamide classes. Many multi-resistance profiles were found among the tested isolates, but especially among those of human origin (all but two isolates showed resistance to at least 13 of 18 antimicrobial agents). Even so, all human isolates were susceptible to gentamicin and tobramycin, while more than 96% of animal isolates were susceptible to these two aminoglycosides. Ciprofloxacin showed activity against more than 92% of animal and human isolates. However, almost 21% of human isolates were resistant to tetracycline, and more than 65% were resistant to tigecycline. Finally, a quite similar activity to other F. tularensis subsp. holarctica isolates collected 20 years earlier in Spain was observed.

scholarly journals The effect of Zinc Oxide Nanoparticles on Pseudomonas Aeruginosa Biofilm Formation and Virulence Genes Expression

2020 ◽  
Author(s):  
wedad abdelraheem ◽  
Ebtisam S. Mohamed
Keyword(s):  
Biofilm Formation ◽  
Virulence Genes ◽  
Antimicrobial Agents ◽  
Public Health Problem ◽  
Microtiter Plate ◽  
Clinical Isolates ◽  
Expression Level ◽  
Microdilution Method ◽  
Genes Expression ◽  
Broth Microdilution Method

Abstract Background: Due to increased resistance to antimicrobial agents, infectious disease remains a public health problem worldwide. Aim: The current study was designed to examine the effect of ZnO nanoparticles (ZnO –np) against the biofilm formation ability of P.aeruginosa clinical isolates and to study its effect on the expression level of the genes involved in biofilm formation and virulence factors production. Methodology: The MIC of ZnO –np against P. aeruginosa was determined by the broth microdilution method. The Effect of ZnO –np on the biofilm-forming isolates of P. aeruginosa was monitored by the microtiter plate method. P.aeruginosa isolates were tested for the expression of different biofilm and virulence genes using real-time rt-PCR. Results: ZnO –np significantly downregulated the expression level of all biofilm and virulence genes of P.aeruginosa clinical isolates except the toxA gene. Conclusions: This study demonstrates the promising use of ZnO –np as an anti-biofilm and anti-virulence compound.

scholarly journals In Vitro Activity of the Siderophore Cephalosporin, Cefiderocol, against Carbapenem-Nonsusceptible and Multidrug-Resistant Isolates of Gram-Negative Bacilli Collected Worldwide in 2014 to 2016

2017 ◽  
Vol 62 (2) ◽  
Author(s):  
Meredith A. Hackel ◽  
Masakatsu Tsuji ◽  
Yoshinori Yamano ◽  
Roger Echols ◽  
James A. Karlowsky ◽  
...  
Keyword(s):  
Burkholderia Cepacia ◽  
Antimicrobial Agents ◽  
Multidrug Resistant ◽  
Clinical Isolates ◽  
Content Type ◽  
Microdilution Method ◽  
Mueller Hinton ◽  
Broth Microdilution Method ◽  
Mueller Hinton Broth

ABSTRACT The in vitro activity of the investigational siderophore cephalosporin, cefiderocol (formerly S-649266), was determined against a 2014–2016, 52-country, worldwide collection of clinical isolates of carbapenem-nonsusceptible Enterobacteriaceae (n = 1,022), multidrug-resistant (MDR) Acinetobacter baumannii (n = 368), MDR Pseudomonas aeruginosa (n = 262), Stenotrophomonas maltophilia (n = 217), and Burkholderia cepacia (n = 4) using the Clinical and Laboratory Standards Institute (CLSI) standard broth microdilution method. Iron-depleted cation-adjusted Mueller-Hinton broth (ID-CAMHB), prepared according to a recently approved (2017), but not yet published, CLSI protocol, was used to test cefiderocol; all other antimicrobial agents were tested using CAMHB. The concentration of cefiderocol inhibiting 90% (MIC90) of isolates of carbapenem-nonsusceptible Enterobacteriaceae was 4 μg/ml; cefiderocol MICs ranged from 0.004 to 32 μg/ml, and 97.0% (991/1,022) of isolates demonstrated cefiderocol MICs of ≤4 μg/ml. The MIC90s for cefiderocol for MDR A. baumannii, MDR P. aeruginosa, and S. maltophilia were 8, 1, and 0.25 μg/ml, respectively, with 89.7% (330/368), 99.2% (260/262), and 100% (217/217) of isolates demonstrating cefiderocol MICs of ≤4 μg/ml. Cefiderocol MICs for B. cepacia ranged from 0.004 to 8 μg/ml. We conclude that cefiderocol demonstrated potent in vitro activity against a 2014–2016, worldwide collection of clinical isolates of carbapenem-nonsusceptible Enterobacteriaceae, MDR A. baumannii, MDR P. aeruginosa, S. maltophilia, and B. cepacia isolates as 96.2% of all (1,801/1,873) isolates tested had cefiderocol MICs of ≤4 μg/ml.

scholarly journals Antimicrobial susceptibility of Pasteurella multocida and Haemophilus parasuis isolates associated with porcine pneumonia

2013 ◽  
Vol 82 (1) ◽  
pp. 3-7 ◽  
Author(s):  
Kateřina Nedbalcová ◽  
Zdeňka Kučerová
Keyword(s):  
Czech Republic ◽  
Pasteurella Multocida ◽  
Antimicrobial Agents ◽  
Haemophilus Parasuis ◽  
The Czech Republic ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Amoxicillin Clavulanic Acid ◽  
High Level ◽  
Resistance Rates

Pasteurella multocidaandHaemophilus parasuispig isolates obtained in the Czech Republic were tested for their susceptibility against selected antimicrobial agents by broth microdilution method between 2008 and 2011. A low degree of resistance was observed for ampicillin, amoxicillin/clavulanic acid, ceftiofur, tulathromycin, tilmicosin, florfenicol and enrofloxacin in 20 (6.0%), 15 (4.5 %), 2 (0.6%), 8 (2.4%), 13 (3.9%), 5 (1.5%) and 5 (1.5%)P. multocidaisolates as well as for tiamulin, gentamicin, tulathromycin, tilmicosin and ampicillin in 2 (2.4%), 2 (2.4%), 3 (3.6%), 3 (3.6%) and 6 (7.2%)H. parasuisisolates. In addition, moderate level of resistance to tiamulin was found in 60 (18.1%)P. multocidaisolates and high level of resistance for tetracycline was detected in 107 (32.2 %)P. multocidaisolates and in 23 (27.7 %)H. parasuisisolates. Differences between resistance rates ofP. multocidaandH. parasuiswere significant (P≤ 0.5) only for tiamulin. These data confirmed that antimicrobial resistance is not very widespread among current porcineP. multocidaandH. parasuisisolates in the Czech Republic.

Dramatic rise in the proportion of ESBL-producing Escherichia coli and Klebsiella pneumoniae among clinical isolates identified in Canadian hospital laboratories from 2007 to 2016

2019 ◽  
Vol 74 (Supplement_4) ◽  
pp. iv64-iv71 ◽  
Author(s):  
Andrew J Denisuik ◽  
James A Karlowsky ◽  
Heather J Adam ◽  
Melanie R Baxter ◽  
Philippe R S Lagacé-Wiens ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Klebsiella Pneumoniae ◽  
Antimicrobial Agents ◽  
Clinical Isolates ◽  
Molecular Characteristics ◽  
E Coli ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Dramatic Rise ◽  
Annual Proportion

Abstract Objectives To assess the prevalence, antimicrobial susceptibilities and molecular characteristics of ESBL-producing Escherichia coli and Klebsiella pneumoniae infecting patients receiving care in Canadian hospitals from January 2007 to December 2016. Methods Clinical isolates of E. coli (n = 8387) and K. pneumoniae (n = 2623) submitted to CANWARD, an ongoing Canadian national surveillance study, were tested using the CLSI reference broth microdilution method to determine their susceptibility to 15 antimicrobial agents. ESBL-producing E. coli and K. pneumoniae confirmed by the CLSI phenotypic method and putative AmpC-producing E. coli underwent PCR testing and DNA sequencing to identify resistance genes. Annual proportions of isolates harbouring ESBL and AmpC genes were assessed by the Cochran–Armitage test of trend. Results The annual proportion of isolates of E. coli that were ESBL producing increased from 3.4% in 2007 to 11.1% in 2016 (P < 0.0001); >95% of ESBL-producing E. coli were susceptible to amikacin, colistin, ertapenem, meropenem and tigecycline. The proportion of isolates of K. pneumoniae that were ESBL producing increased from 1.3% in 2007 to 9.7% in 2016 (P < 0.0001); >95% of ESBL-producing K. pneumoniae were susceptible to amikacin and meropenem. CTX-M-15 was the predominant genotype in both ESBL-producing E. coli (64.2% of isolates) and ESBL-producing K. pneumoniae (51.0%). The annual proportion of isolates of E. coli that were AmpC producing [annual proportion mean 1.9% (range 0.3%–3.1%)] was unchanged from 2007 to 2016 (P > 0.5). Conclusions The prevalence of both ESBL-producing E. coli and K. pneumoniae increased significantly in Canada during the study period while the prevalence of AmpC-producing E. coli remained low and stable.

scholarly journals In Vitro Activity of Eravacycline against Gram-Negative Bacilli Isolated in Clinical Laboratories Worldwide from 2013 to 2017

2019 ◽  
Vol 64 (3) ◽  
Author(s):  
Ian Morrissey ◽  
Melanie Olesky ◽  
Stephen Hawser ◽  
Sibylle H. Lob ◽  
James A. Karlowsky ◽  
...  
Keyword(s):  
Antimicrobial Agents ◽  
Multidrug Resistant ◽  
Clinical Isolates ◽  
Gram Negative ◽  
Content Type ◽  
Microdilution Method ◽  
Clinical Laboratories ◽  
Serious Infections ◽  
Broth Microdilution Method

ABSTRACT Eravacycline is a novel, fully synthetic fluorocycline antibiotic developed for the treatment of serious infections, including those caused by multidrug-resistant (MDR) pathogens. Here, we evaluated the in vitro activities of eravacycline and comparator antimicrobial agents against a global collection of frequently encountered clinical isolates of Gram-negative bacilli. The CLSI broth microdilution method was used to determine MIC data for isolates of Enterobacterales (n = 13,983), Acinetobacter baumannii (n = 2,097), Pseudomonas aeruginosa (n = 1,647), and Stenotrophomonas maltophilia (n = 1,210) isolated primarily from respiratory, intra-abdominal, and urinary specimens by clinical laboratories in 36 countries from 2013 to 2017. Susceptibilities were interpreted using both CLSI and EUCAST breakpoints. Multidrug-resistant (MDR) isolates were defined by resistance to agents from ≥3 different antimicrobial classes. The MIC90s ranged from 0.25 to 1 μg/ml for Enterobacteriaceae and were 1 μg/ml for A. baumannii and 2 μg/ml for S. maltophilia, Proteus mirabilis, and Serratia marcescens. Eravacycline’s potency was up to 4-fold greater than that of tigecycline against genera/species of Enterobacterales, A. baumannii, and S. maltophilia. The MIC90s for five of six individual genera/species of Enterobacterales and A. baumannii were within 2-fold of the MIC90s for their respective subsets of MDR isolates, while the MDR subpopulation of Klebsiella spp. demonstrated 4-fold higher MIC90s. Eravacycline demonstrated potent in vitro activity against the majority of clinical isolates of Gram-negative bacilli, including MDR isolates, collected over a 5-year period. This study further underscores the potential benefit of eravacycline in the treatment of infections caused by MDR Gram-negative pathogens.

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