scholarly journals Antimicrobial Susceptibility of Corynebacterium bovis Isolates from Immunodeficient Rodents

2021 ◽  
Author(s):  
Anna C Fagre ◽  
Uma Pugazhenthi ◽  
Christopher Cheleuitte-Nieves ◽  
Marcus J Crim ◽  
Kenneth S Henderson ◽  
...  
Keyword(s):  
Antimicrobial Susceptibility ◽  
Antimicrobial Agents ◽  
The United States ◽  
Immunodeficient Mice ◽  
Gram Positive Bacteria ◽  
Oncology Research ◽  
Skin Colonization ◽  
Resistant Strains ◽  
Susceptibility Profiles ◽  
Poor Efficacy

Corynebacterium bovis, the causative agent of hyperkeratotic dermatitis in immunodeficient mice, is a significant problemin preclinical oncology research. Infection results in lifelong skin colonization and a decrease in successful engraftment ofpatient-derived xenograft tumor models. The use of antimicrobial agents for C. bovis is controversial in light of reports of poor efficacy and the possibility of selection for resistant strains. The purpose of this study was to describe the antimicrobial susceptibilities of C. bovis isolates obtained exclusively from immunodeficient rodents in order to aid in antimicrobial dose determination. Between 1995 and 2018, 15 isolates were collected from 11 research institutions across the United States. Antimicrobial susceptibility testing was performed for 24 antimicrobials commonly used against gram-positive bacteria. Our results provide an updated understanding of the susceptibility profiles of rodent C. bovis isolates, indicating little variability between geographically and temporally distant isolates. These results will facilitate appropriate antimicrobial use to prevent and treat C. bovis infections in immunodeficient rodents.

scholarly journals Antimicrobial Susceptibility to Azithromycin among Salmonella enterica Isolates from the United States

2011 ◽  
Vol 55 (9) ◽  
pp. 3985-3989 ◽  
Author(s):  
Maria Sjölund-Karlsson ◽  
Kevin Joyce ◽  
Karen Blickenstaff ◽  
Takiyah Ball ◽  
Jovita Haro ◽  
...  
Keyword(s):  
United States ◽  
Antimicrobial Susceptibility ◽  
Salmonella Enterica ◽  
Antimicrobial Agents ◽  
The United States ◽  
Outcome Data ◽  
Content Type ◽  
Susceptibility Data ◽  
Retail Meat ◽  
Clinical Breakpoints

ABSTRACTDue to emerging resistance to traditional antimicrobial agents, such as ampicillin, trimethoprim-sulfamethoxazole, and chloramphenicol, azithromycin is increasingly used for the treatment of invasiveSalmonellainfections. In the present study, 696 isolates of non-TyphiSalmonellacollected from humans, food animals, and retail meats in the United States were investigated for antimicrobial susceptibility to azithromycin. Seventy-twoSalmonella entericaserotype Typhi isolates from humans were also tested. For each isolate, MICs of azithromycin and 15 other antimicrobial agents were determined by broth microdilution. Among the non-TyphiSalmonellaisolates, azithromycin MICs among human isolates ranged from 1 to 32 μg/ml, whereas the MICs among the animal and retail meat isolates ranged from 2 to 16 μg/ml and 4 to 16 μg/ml, respectively. AmongSalmonellaserotype Typhi isolates, the azithromycin MICs ranged from 4 to 16 μg/ml. The highest MIC observed in the present study was 32 μg/ml, and it was detected in three human isolates belonging to serotypes Kentucky, Montevideo, and Paratyphi A. Based on our findings, we propose an epidemiological cutoff value (ECOFF) for wild-typeSalmonellaof ≤16 μg/ml of azithromycin. The susceptibility data provided could be used in combination with clinical outcome data to determine tentative clinical breakpoints for azithromycin andSalmonella enterica.

scholarly journals Antimicrobial susceptibility of Salmonella Gallinarum and Salmonella Pullorum isolated from ill poultry in Brazil

2016 ◽  
Vol 46 (3) ◽  
pp. 513-518 ◽  
Author(s):  
Rafael Antonio Casarin Penha Filho ◽  
Joseane Cristina Ferreira ◽  
Ana Maria Iba Kanashiro ◽  
Ana Lúcia da Costa Darini ◽  
Angelo Berchieri Junior
Keyword(s):  
High Mortality ◽  
Antimicrobial Susceptibility ◽  
Antimicrobial Agents ◽  
Gastrointestinal Infections ◽  
Salmonella Gallinarum ◽  
Poultry Farms ◽  
Salmonella Pullorum ◽  
Low Levels ◽  
Susceptibility Profiles ◽  
Over Time

ABSTRACT: Salmonella Gallinarum (S. Gallinarum) and Salmonella Pullorum (S. Pullorum) are poultry host-specific, agents of fowl typhoid and pullorum disease, respectively. These biovars cause septicemic infections, resulting in high mortality. Outbreaks are frequently reported worldwide, causing losses due to the elimination of infected flocks and treatments. The use of antimicrobial agents is frequent in poultry farms to prevent or treat gastrointestinal infections. In the present research it was evaluated the antimicrobial susceptibility of 50 S. Gallinarum and S. Pullorum isolates, from outbreaks that occurred between 1987 to 1991 and 2006 to 2013. The comparison of the susceptibility profiles showed that all isolates were susceptible to β-lactams. All isolates from 1987-1991 were susceptible to all antibiotics tested except NAL and CIP (78%). The susceptibility profile of S. Gallinarum (2006 - 2013 period) was the following NAL (58%), CIP (63%), ENR (67%), TET (92%), FFC (96%) and SXT (96%). S. Pullorum isolates (2006 - 2013 period) showed the following susceptibility rates to NAL (65%), CIP (71%), ENR (94%) and TET (94%). All isolates were susceptible to β-lactams tested, however, resistance to quinolones and fluoroquinolones increased over time. Furthermore, low levels of resistance to other antibiotics were found in recent isolates, such as tetracyclines.

scholarly journals Antimicrobial Susceptibility and Clonality of Clinical Ureaplasma Isolates in the United States

2016 ◽  
Vol 60 (8) ◽  
pp. 4793-4798 ◽  
Author(s):  
Javier Fernández ◽  
Melissa J. Karau ◽  
Scott A. Cunningham ◽  
Kerryl E. Greenwood-Quaintance ◽  
Robin Patel
Keyword(s):  
United States ◽  
Antimicrobial Susceptibility ◽  
Antimicrobial Agents ◽  
Ureaplasma Urealyticum ◽  
Resistance Mechanism ◽  
The United States ◽  
Resistance Mechanisms ◽  
Resistant Isolate ◽  
Limited Information ◽  
Content Type

ABSTRACTUreaplasma urealyticumandUreaplasma parvumare pathogens involved in urogenital tract and intrauterine infections and also in systemic diseases in newborns and immunosuppressed patients. There is limited information on the antimicrobial susceptibility and clonality of these species. In this study, we report the susceptibility of 250 contemporary isolates ofUreaplasma(202U. parvumand 48U. urealyticumisolates) recovered at Mayo Clinic, Rochester, MN. MICs of doxycycline, azithromycin, ciprofloxacin, tetracycline, erythromycin, and levofloxacin were determined by broth microdilution, with MICS of the last three interpreted according to CLSI guidelines. Levofloxacin resistance was found in 6.4% and 5.2% ofU. parvumandU. urealyticumisolates, respectively, while 27.2% and 68.8% of isolates, respectively, showed ciprofloxacin MICs of ≥4 μg/ml. The resistance mechanism of levofloxacin-resistant isolates was due to mutations inparC, with the Ser83Leu substitution being most frequent, followed by Glu87Lys. No macrolide resistance was found among the 250 isolates studied; a singleU. parvumisolate was tetracycline resistant.tet(M) was found in 10U. parvumisolates, including the single tetracycline-resistant isolate, as well as in 9 isolates which had low tetracycline and doxycycline MICs. Multilocus sequence typing (MLST) performed on a selection of 46 isolates showed high diversity within the clinicalUreaplasmaisolates studied, regardless of antimicrobial susceptibility. The present work extends previous knowledge regarding susceptibility to antimicrobial agents, resistance mechanisms, and clonality ofUreaplasmaspecies in the United States.

scholarly journals Antimicrobial susceptibility profiles of Staphylococcus intermedius isolates from clinical cases of canine pyoderma in South Africa

2013 ◽  
Vol 84 (1) ◽  
Author(s):  
Catherine A. Blunt ◽  
Moritz Van Vuuren ◽  
Jacqueline Picard
Keyword(s):  
Antimicrobial Resistance ◽  
Antimicrobial Susceptibility ◽  
Bacterial Resistance ◽  
Antimicrobial Agents ◽  
Temporal Trends ◽  
Companion Animals ◽  
Diagnostic Laboratory ◽  
Staphylococcus Intermedius ◽  
Susceptibility Profiles ◽  
Broth Dilution

Successful treatment of canine pyoderma has become compromised owing to the development of antimicrobial resistance with accompanying recurrence of infection. Canine skin samples submitted to a veterinary diagnostic laboratory for microbiological culture and sensitivity between January 2007 and June 2010, from which Staphylococcus intermedius was isolated, were selected for this investigation. Antimicrobial resistance of S. intermedius was most prevalent with reference to ampicillin followed by resistance to tetracycline and then potentiated sulphonamides. In general, antimicrobial resistance was low and very few methicillin-resistant isolates were detected. Temporal trends were not noted, except for ampicillin, with isolates becoming more susceptible, and potentiated sulphonamides (co-trimoxazole), with isolates becoming more resistant. In general, both the Kirby–Bauer disc diffusion and broth dilution minimum inhibitory concentration tests yielded similar results for the antimicrobial agents tested. The main difference was evident in the over-estimation of resistance by the Kirby–Bauer test for ampicillin, co-trimoxazole, penicillin and doxycycline. Knowledge of trends in bacterial resistance is important for veterinarians when presented with canine pyoderma. Analysis of antimicrobial susceptibility profiles of S. intermedius isolated from canine pyodermas will guide veterinarians’ use of the most appropriate agent and encourage prudent use of antimicrobials in companion animals.

Disinfectant and Antimicrobial Susceptibility Profiles of the Big Six Non-O157 Shiga Toxin–Producing Escherichia coli Strains from Food Animals and Humans

2016 ◽  
Vol 79 (8) ◽  
pp. 1355-1370 ◽  
Author(s):  
ROSS C. BEIER ◽  
EELCO FRANZ ◽  
JAMES L. BONO ◽  
ROBERT E. MANDRELL ◽  
PINA M. FRATAMICO ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Susceptibility ◽  
Shiga Toxin ◽  
Human Exposure ◽  
Antimicrobial Agents ◽  
Active Components ◽  
Food Animals ◽  
Low Prevalence ◽  
Susceptibility Profiles ◽  
Animal Strains

ABSTRACT The disinfectant and antimicrobial susceptibility profiles of 138 non-O157 Shiga toxin–producing Escherichia coli strains (STECs) from food animals and humans were determined. Antimicrobial resistance (AMR) was moderate (39.1% of strains) in response to 15 antimicrobial agents. Animal strains had a lower AMR prevalence (35.6%) than did human strains (43.9%) but a higher prevalence of the resistance profile GEN-KAN-TET. A decreasing prevalence of AMR was found among animal strains from serogroups O45 > O145 > O121 > O111 > O26 > O103 and among human strains from serogroups O145 > O103 > O26 > O111 > O121 > O45. One animal strain from serogroups O121 and O145 and one human strain from serogroup O26 had extensive drug resistance. A high prevalence of AMR in animal O45 and O121 strains and no resistance or a low prevalence of resistance in human strains from these serogroups suggests a source other than food animals for human exposure to these strains. Among the 24 disinfectants evaluated, all strains were susceptible to triclosan. Animal strains had a higher prevalence of resistance to chlorhexidine than did human strains. Both animal and human strains had a similar low prevalence of low-level benzalkonium chloride resistance, and animal and human strains had similar susceptibility profiles for most other disinfectants. Benzyldimethylammonium chlorides and C10AC were the primary active components in disinfectants DC&R and P-128, respectively, against non-O157 STECs. A disinfectant FS512 MIC ≥ 8 μg/ml was more prevalent among animal O121 strains (61.5%) than among human O121 strains (25%), which may also suggest a source of human exposure to STEC O121 other than food animals. Bacterial inhibition was not dependent solely on pH but was correlated with the presence of dissociated organic acid species and some undissociated acids.

scholarly journals Antimicrobial Susceptibility and Synergy Studies of Stenotrophomonas maltophilia Isolates from Patients with Cystic Fibrosis

2004 ◽  
Vol 48 (1) ◽  
pp. 168-171 ◽  
Author(s):  
Pablo San Gabriel ◽  
Juyan Zhou ◽  
Setareh Tabibi ◽  
Yunhua Chen ◽  
Marco Trauzzi ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Antimicrobial Susceptibility ◽  
Stenotrophomonas Maltophilia ◽  
Antimicrobial Agents ◽  
Active Agent ◽  
The United States ◽  
Multidrug Resistant ◽  
Resistant Organism ◽  
High Concentrations ◽  
The Impact

ABSTRACT Stenotrophomonas maltophilia is a newly emerging pathogen being detected with increasing frequency in patients with cystic fibrosis (CF). The impact of this multidrug-resistant organism on lung function is uncertain. The optimal treatment for S. maltophilia in CF patients is unknown. We studied the in vitro activity of ten antimicrobial agents, and conducted synergy studies by using checkerboard dilutions of eight pairs of antimicrobial agents against strains isolated from 673 CF patients from 1996 to 2001. This represents approximately 7 to 23% of the CF patients in the United States who harbor S. maltophilia annually. Doxycycline was the most active agent and inhibited 80% of 673 initial patient isolates, while trimethoprim-sulfamethoxazole inhibited only 16%. High concentrations of colistin proved more active than high concentrations of tobramycin and gentamicin. Serial isolates (n = 151) from individual patients over time (median, 290 days) showed minimal changes in resistance. Synergistic or additive activity was demonstrated by trimethoprim-sulfamethoxazole paired with ticarcillin-clavulanate (65% of strains), ciprofloxacin paired with ticarcillin-clavulanate (64% of strains), ciprofloxacin paired with piperacillin-tazobactam (59% of strains), trimethoprim-sulfamethoxazole paired with piperacillin-tazobactam (55% of strains), and doxycycline paired with ticarcillin-clavulanate (49% of strains). In all, 522 (78%) isolates were multidrug resistant (i.e., resistant to all agents in two or more antimicrobial classes) but 473 (91%) of these were inhibited by at least one antimicrobial combination (median, four; range, one to eight). To determine appropriate treatment for patients with CF, it is important to monitor the prevalence, antimicrobial susceptibility, and clinical impact of S. maltophilia in this patient population.

scholarly journals 1534. Polymyxin Antimicrobial Susceptibility (AST) Testing and Breakpoints for P. aeruginosa, A. baumannii, and Enterobacteriaceae: Recommendations from the United States Committee on Antimicrobial Susceptibility Testing (USCAST)

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S559-S559
Author(s):  
Jason M Pogue ◽  
Ronald N Jones ◽  
John S Bradley ◽  
David Andes ◽  
Sujata M Bhavnani ◽  
...  
Keyword(s):  
Antimicrobial Susceptibility ◽  
Antimicrobial Agents ◽  
Package Insert ◽  
Polymyxin B ◽  
The United States ◽  
Multidrug Resistant ◽  
Outcome Data ◽  
Published Data ◽  
Tract Infections

Abstract Background Polymyxins are important antimicrobial agents for the treatment of infections due to carbapenem-resistant and other multidrug-resistant organisms. Recently, the CLSI and EUCAST have set breakpoints for colistin (EUCAST and CLSI) and polymyxin B (CLSI) with slight differences in recommendations. However, there are issues unique to the polymyxin class that warrant additional guidances. Herein, we assess data related to breakpoint setting and make additional recommendations for polymyxin AST interpretive criteria. Methods Data sources included longitudinal (2011–2017) US surveillance reference broth microdilution (BMD) MIC distributions (128,573 isolates) for colistin and polymyxin B (PB), published data on accuracy of various AST methodologies, in vivo pharmacokinetic/pharmacodynamic (PK-PD) models, prior polymyxin guidelines and agency package insert dosing recommendations, and population PK-PD and toxicodynamic (TD) data. Epidemiological cut-off, PK-PD (and TD), and clinical data were all considered for susceptible (S) breakpoint determinations. Results Data demonstrate that the most commonly utilized AST methodologies (disk diffusion, Etest, and automated MIC susceptibility panels), as well as agar dilution testing cannot reliably detect resistance; and BMD is the preferred AST. Importantly, colistin S is a reliable surrogate for PB S with cross-S accuracy at > 99% of isolates in each pathogen group. Breakpoint recommendations can be found in the Table with emphasis on applying combination therapy. Key recommendations include an S breakpoint of ≤2 mg/L for each pathogen (both colistin and PB). However, based on a lack of preclinical efficacy in murine pneumonia models, PK/PD concerns, and poor clinical outcome data, we strongly suggest that no breakpoints are applied for pneumonia and that alternative therapies should be used where available. Additionally, due to a lack of significant renal excretion, PB will also have no S breakpoint recommendation for lower urinary tract infections. Conclusion The polymyxins have compromising characteristics that make them suboptimal antimicrobials when used alone, and additional caveats are required for AST breakpoint interpretive criteria and stewardship programs. Disclosures All authors: No reported disclosures.

scholarly journals Baseline Study To Determine In Vitro Activities of Daptomycin against Gram-Positive Pathogens Isolated in the United States in 2000-2001

2003 ◽  
Vol 47 (5) ◽  
pp. 1689-1693 ◽  
Author(s):  
Ian A. Critchley ◽  
Renée S. Blosser-Middleton ◽  
Mark E. Jones ◽  
Clyde Thornsberry ◽  
Daniel F. Sahm ◽  
...  
Keyword(s):  
United States ◽  
Outpatient Care ◽  
Antimicrobial Agents ◽  
The United States ◽  
Multidrug Resistant ◽  
Gram Positive ◽  
Gram Positive Bacteria ◽  
Oxacillin Resistance ◽  
Positive Spectrum

ABSTRACT The activity of daptomycin was assessed by using 6,973 gram-positive bacteria isolated at 50 United States hospitals in 2000 and 2001. Among the isolates of Streptococcus pneumoniae (n = 1,163) collected, the rate of penicillin resistance was 16.1%; rates of oxacillin resistance among Staphylococcus aureus isolates (n = 1,018) and vancomycin resistance among Enterococcus faecium isolates (n = 368) were 30.0 and 59.5%, respectively. Multidrug-resistant (MDR) phenotypes (isolates resistant to three or more different chemical classes of antimicrobial agents) accounted for 14.2% of S. pneumoniae isolates, 27.1% of S. aureus isolates, and 58.4% of E. faecium isolates. For all gram-positive species tested, MICs at which 90% of the isolates tested were inhibited (MIC90s) and MIC ranges for directed-spectrum agents (daptomycin, quinupristin-dalfopristin, and linezolid) were identical or highly similar for isolates susceptible or resistant to other agents or MDR. Daptomycin had a MIC90 of 0.12 μg/ml for both penicillin-susceptible and -resistant isolates of S. pneumoniae. Against oxacillin-resistant S. aureus daptomycin had a MIC90 of 0.5 μg/ml, and it had a MIC90 of 4 μg/ml against both vancomycin-susceptible and -resistant E. faecium. The MIC90s for daptomycin and other directed-spectrum agents were unaffected by the regional or anatomical origin of isolates or patient demographic parameters (patient age, gender, and inpatient or outpatient care). Our results confirm the gram-positive spectrum of activity of daptomycin and that its activity is independent of susceptibility or resistance to commonly prescribed and tested antimicrobial agents. This study may serve as a baseline to monitor future changes in the susceptibility of gram-positive species to daptomycin following its introduction into clinical use.

scholarly journals Drug Susceptibility of 33 Reference Strains of Slowly Growing Mycobacteria to 19 Antimicrobial Agents

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Hui Pang ◽  
Yi Jiang ◽  
Kanglin Wan
Keyword(s):  
Antimicrobial Activity ◽  
Oral Administration ◽  
Antimicrobial Susceptibility ◽  
Antimicrobial Agents ◽  
Drug Susceptibility ◽  
Mycobacterium Intracellulare ◽  
Microdilution Method ◽  
Susceptibility Profiles ◽  
Mycobacterium Simiae ◽  
Reference Strains

Objectives. Slowly growing mycobacteria (SGM) are prevalent worldwide and cause an extensive spectrum of diseases. Methods. In this study, the antimicrobial susceptibility of 33 reference strains of SGM to 19 antimicrobial agents was tested using a modified microdilution method. Results. Cefmetazole (32/33) and azithromycin (32/33) exhibited the highest antimicrobial activity, and dapsone (9/33) exhibited the lowest activity against the tested strains. Cefoxitin (30/33), cefoperazone (28/33), and cefepime (28/33) were effective against a high proportion of strains, and macrolides were also highly effective as well as offering the benefit of convenient oral administration to patients. Linezolid (27/33), meropenem (26/33), sulfamethoxazole (26/33), and tigecycline (25/33) showed the highest activity; clofazimine (20/33) and doxycycline (18/33) showed intermediate activity; and rifapentine (13/33), rifabutin (13/33), and minocycline (11/33) showed low antimicrobial activity, closely followed by thioacetazone (10/33) and pasiniazid (10/33), against the tested organisms. According to their susceptibility profiles, the slowly growing species Mycobacterium avium and Mycobacterium simiae were the least susceptible to the tested drugs, whereas Mycobacterium intracellulare, Mycobacterium asiaticum, Mycobacterium scrofulaceum, Mycobacterium szulgai, Mycobacterium branderi, and Mycobacterium holsaticum were the most susceptible. Conclusions. In summary, cephalosporins and macrolides, particularly cefmetazole, azithromycin, clarithromycin, and roxithromycin, showed good antimicrobial activity against the reference strains of SGM.

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