scholarly journals Use of Animal Models To Support Revising Meningococcal Breakpoints of β-Lactams

2016 ◽  
Vol 60 (7) ◽  
pp. 4023-4027 ◽  
Author(s):  
Nouria Belkacem ◽  
Eva Hong ◽  
Ana Antunes ◽  
Aude Terrade ◽  
Ala-Eddine Deghmane ◽  
...  
Keyword(s):  
Human Factor ◽  
Susceptibility Testing ◽  
Bioluminescence Imaging ◽  
Factor H ◽  
Penicillin G ◽  
High Dose ◽  
Beta Lactams ◽  
Content Type ◽  
Resistance To Penicillin ◽  
Intraperitoneal Infection

ABSTRACTAntibiotic susceptibility testing (AST) inNeisseria meningitidisis an important part of the management of invasive meningococcal disease. It defines MICs of antibiotics that are used in treatment and/or prophylaxis and that mainly belong to the beta-lactams. The interpretation of the AST results requires breakpoints to classify the isolates into susceptible, intermediate, or resistant. The resistance to penicillin G is defined by a MIC of >0.25 mg/liter, and that of amoxicillin is defined by a MIC of >1 mg/liter. We provide data that may support revision of resistance breakpoints for beta-lactams in meningococci. We used experimental intraperitoneal infection in 8-week-old transgenic female mice expressing human transferrin and human factor H. Dynamic bioluminescence imaging was performed to follow the infection by bioluminescent meningococcus strains with different MICs. Three hours later, infected mice were treated intramuscularly using several doses of amoxicillin or penicillin G. Signal decreased during infection with a meningococcus strain showing a penicillin G MIC of 0.064 mg/liter at all doses. Signals decreased for the strain with a penicillin G MIC of 0.5 mg/liter only after treatment with the highest doses, corresponding to 250,000 units/kg of penicillin G or 200 mg/kg of amoxicillin, although this decrease was at a lower rate than that of the strain with a MIC of 0.064 mg/liter. The decrease in bioluminescent signals was associated with a decrease in the levels of the proinflammatory cytokine interleukin-6 (IL-6). Our data suggest that a high dose of amoxicillin or penicillin G can reduce growth during infection by isolates showing penicillin G MICs of >0.25 mg/liter and ≤1 mg/liter.

Binding of Staphylococcus aureus to milk fat globules increases resistance to penicillin-G

1997 ◽  
Vol 64 (2) ◽  
pp. 253-260 ◽  
Author(s):  
TERHI ALI-VEHMAS ◽  
PETER WESTPHALEN ◽  
VESA MYLLYS ◽  
MARKUS SANDHOLM
Keyword(s):  
Staphylococcus Aureus ◽  
Milk Fat ◽  
Susceptibility Testing ◽  
Binding Capacity ◽  
Penicillin G ◽  
Capsule Formation ◽  
Minimal Inhibitory Concentrations ◽  
Fat Globules ◽  
Milk Fat Globules ◽  
Resistance To Penicillin

The susceptibility to penicillin-G of Staphylococcus aureus strains that cause mastitis was tested in milk and in Iso-sensitest broth (ISB). The minimal inhibitory concentrations (MIC) of β-lactamase-positive strains in milk were 10–100-fold those in ISB, whereas the MIC of β-lactamase-negative strains in milk were some 10-fold those in ISB; β-lactamase production was induced by milk in β-lactamase-positive strains. Much of the increase in resistance to penicillin-G caused by milk can be attributed to milk fat globules; the increase in resistance was related to the binding capacity of the bacteria to milk fat globules as well as to capsule formation by the bacteria. It appears that the binding of the staphylococci to the fat globules and bacterial capsule formation resulted in a biofilm type of growth. In this case, the staphylococci behaved differently from the planktonic type of growth in artificial broth medium in which antibiotic susceptibility testing is usually carried out.

scholarly journals Biofilm Compared to Conventional Antimicrobial Susceptibility of Stenotrophomonas maltophilia Isolates from Cystic Fibrosis Patients

2013 ◽  
Vol 57 (3) ◽  
pp. 1546-1548 ◽  
Author(s):  
Kitty Wu ◽  
Yvonne C. W. Yau ◽  
Larissa Matukas ◽  
Valerie Waters
Keyword(s):  
Cystic Fibrosis ◽  
Antimicrobial Susceptibility ◽  
Stenotrophomonas Maltophilia ◽  
Susceptibility Testing ◽  
Multidrug Resistant ◽  
Resistant Organism ◽  
High Dose ◽  
Content Type

ABSTRACTStenotrophomonas maltophiliais a multidrug-resistant organism increasingly isolated from the lungs of cystic fibrosis (CF) patients. One hundred twenty-fiveS. maltophiliaisolates from 85 CF patients underwent planktonic and biofilm susceptibility testing against 9 different antibiotics, alone and in double antibiotic combinations. WhenS. maltophiliaisolates were grown as a biofilm, 4 of the 10 most effective antibiotic combinations included high-dose levofloxacin and 7 of the 10 combinations included colistin at doses achievable by aerosolization.

scholarly journals Antimicrobial Susceptibility of Propionibacterium acnes Isolates from Shoulder Surgery

2013 ◽  
Vol 57 (7) ◽  
pp. 3424-3426 ◽  
Author(s):  
John K. Crane ◽  
Donald W. Hohman ◽  
Scott R. Nodzo ◽  
Thomas R. Duquin
Keyword(s):  
Antimicrobial Susceptibility ◽  
Susceptibility Testing ◽  
Propionibacterium Acnes ◽  
Shoulder Surgery ◽  
Antimicrobial Susceptibility Testing ◽  
Penicillin G ◽  
Microbiology Laboratory ◽  
Content Type ◽  
Orthopedic Surgeons

ABSTRACTOrthopedic surgeons at our institution have noticed an increase in the number of infections due toPropionibacterium acnes, especially following operations on the shoulder. We collectedP. acnesisolates from our hospital microbiology laboratory for 1 year and performed antimicrobial susceptibility testing on 28 strains from the shoulder. Antibiotics with the lowest MIC values againstP. acnes(MIC50and MIC90) included penicillin G (0.006, 0.125), cephalothin (0.047 and 0.094), and ceftriaxone (0.016, 0.045), while others also showed activity. Strains resistant to clindamycin were noted.

scholarly journals Haemophilus influenzae with Non-Beta-Lactamase-Mediated Beta-Lactam Resistance: Easy To Find but Hard To Categorize

2015 ◽  
Vol 53 (11) ◽  
pp. 3589-3595 ◽  
Author(s):  
Dagfinn Skaare ◽  
Astrid Lia ◽  
Anja Hannisdal ◽  
Yngvar Tveten ◽  
Erika Matuschek ◽  
...  
Keyword(s):  
Haemophilus Influenzae ◽  
Disk Diffusion ◽  
High Dose ◽  
Beta Lactamase ◽  
Penicillin Binding Protein ◽  
Beta Lactam ◽  
Beta Lactams ◽  
Content Type ◽  
Severe Infections ◽  
Clinical Breakpoints

Haemophilus influenzaeis a major pathogen, and beta-lactams are first-line drugs. Resistance due to altered penicillin-binding protein 3 (rPBP3) is frequent, and susceptibility testing of such strains is challenging. A collection of 154 beta-lactamase-negative isolates with a large proportion of rPBP3 (67.5%) was used to evaluate and compare Etest (Haemophilustest medium [HTM]) and disk diffusion (EUCAST method) for categorization of susceptibility to aminopenicillins and cefuroxime, using MICs generated with broth (HTM) microdilution and clinical breakpoints from CLSI and EUCAST as the gold standards. In addition, the proficiency of nine disks in screening for the rPBP3 genotype (N526K positive) was evaluated. By Etest, both essential and categorical agreement were generally poor (<70%), with high very major errors (VME) (CLSI, 13.0%; EUCAST, 34.3%) and falsely susceptible rates (FSR) (CLSI, 87.0%; EUCAST, 88.3%) for ampicillin. Ampicillin (2 μg) with adjusted (+2 mm) zone breakpoints was superior to Etest for categorization of susceptibility to ampicillin (agreement, 74.0%; VME, 11.0%; FSR, 28.3%). Conversely, Etest was superior to 30 μg cefuroxime for categorization of susceptibility to cefuroxime (agreement, 57.1% versus 60.4%; VME, 2.6% versus 9.7%; FSR, 7.1% versus 26.8%). Benzylpenicillin (1 unit) (EUCAST screening disk) and cefuroxime (5 μg) identified rPBP3 isolates with highest accuracies (95.5% and 92.2%, respectively). In conclusion, disk screening reliably detects rPBP3H. influenzae, but false ampicillin susceptibility is frequent with routine methods. We suggest adding a comment recommending high-dose aminopenicillin therapy or the use of other agents for severe infections with screening-positive isolates that are susceptible to aminopenicillins by gradient or disk diffusion.

scholarly journals Role for Gr-1+Cells in the Control of High-Dose Mycobacterium bovis Recombinant BCG

2014 ◽  
Vol 21 (8) ◽  
pp. 1120-1127 ◽  
Author(s):  
Michael W. Panas ◽  
Norman L. Letvin
Keyword(s):  
Immune Response ◽  
Mycobacterium Bovis ◽  
Bioluminescence Imaging ◽  
Adaptive Immune Response ◽  
Vaccine Vector ◽  
High Dose ◽  
Mycobacterial Antigen ◽  
Content Type ◽  
Inflammatory Monocytes ◽  
Recombinant Bcg

ABSTRACTMycobacterium bovisbacillus Calmette-Guérin (BCG) is an attractive target for development as a live vaccine vector delivering transgenic antigens from HIV and other pathogens. Most studies aimed at defining the clearance of BCG have been performed at doses between 102and 104CFU. Interestingly, however, recombinant BCG (rBCG) administered at doses of >106CFU effectively generates antigen-specific T-cell responses and primes for heterologous boost responses. Thus, defining clearance at high doses might aid in the optimization of rBCG as a vector. In this study, we used bioluminescence imaging to examine the kinetics of rBCG transgene expression and clearance in mice immunized with 5 × 107CFU rBCG expressing luciferase. Similar to studies using low-dose rBCG, our results demonstrate that the adaptive immune response is necessary for long-term control of rBCG beginning 9 days after immunizing mice. However, in contrast to these reports, we observed that the majority of mycobacterial antigen was eliminated prior to day 9. By examining knockout and antibody-mediated depletion mouse models, we demonstrate that the rapid clearance of rBCG occurs in the first 24 h and is mediated by Gr-1+cells. As Gr-1+granulocytes have been described as having no impact on BCG clearance at low doses, our results reveal an unappreciated role for Gr-1+neutrophils and inflammatory monocytes in the clearance of high-dose rBCG. This work demonstrates the potential of applying bioluminescence imaging to rBCG in order to gain an understanding of the immune response and increase the efficacy of rBCG as a vaccine vector.

scholarly journals Fosfomycin plus β-Lactams as Synergistic Bactericidal Combinations for Experimental Endocarditis Due to Methicillin-Resistant and Glycopeptide-Intermediate Staphylococcus aureus

2015 ◽  
Vol 60 (1) ◽  
pp. 478-486 ◽  
Author(s):  
A. del Río ◽  
C. García-de-la-Mària ◽  
J. M. Entenza ◽  
O. Gasch ◽  
Y. Armero ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Standard Dose ◽  
High Dose ◽  
Penicillin Binding Protein ◽  
Beta Lactams ◽  
Methicillin Resistant ◽  
Content Type ◽  
Time Kill

ABSTRACTThe urgent need of effective therapies for methicillin-resistantStaphylococcus aureus(MRSA) infective endocarditis (IE) is a cause of concern. We aimed to ascertain thein vitroandin vivoactivity of the older antibiotic fosfomycin combined with different beta-lactams against MRSA and glycopeptide-intermediate-resistantS. aureus(GISA) strains. Time-kill tests with 10 isolates showed that fosfomycin plus imipenem (FOF+IPM) was the most active evaluated combination. In an aortic valve IE model with two strains (MRSA-277H and GISA-ATCC 700788), the following intravenous regimens were compared: fosfomycin (2 g every 8 h [q8h]) plus imipenem (1 g q6h) or ceftriaxone (2 g q12h) (FOF+CRO) and vancomycin at a standard dose (VAN-SD) (1 g q12h) and a high dose (VAN-HD) (1 g q6h). Whereas a significant reduction of MRSA-227H load in the vegetations (veg) was observed with FOF+IPM compared with VAN-SD (0 [interquartile range [IQR], 0 to 1] versus 2 [IQR, 0 to 5.1] log CFU/g veg;P= 0.01), no statistical differences were found with VAN-HD. In addition, FOF+IPM sterilized more vegetations than VAN-SD (11/15 [73%] versus 5/16 [31%];P= 0.02). The GISA-ATCC 700788 load in the vegetations was significantly lower after FOF+IPM or FOF+CRO treatment than with VAN-SD (2 [IQR, 0 to 2] and 0 [IQR, 0 to 2] versus 6.5 [IQR, 2 to 6.9] log CFU/g veg;P< 0.01). The number of sterilized vegetations after treatment with FOF+CRO was higher than after treatment with VAN-SD or VAN-HD (8/15 [53%] versus 4/20 [20%] or 4/20 [20%];P= 0.03). To assess the effect of FOF+IPM on penicillin binding protein (PBP) synthesis, molecular studies were performed, with results showing that FOF+IPM treatment significantly decreased PBP1, PBP2 (but not PBP2a), and PBP3 synthesis. These results allow clinicians to consider the use of FOF+IPM or FOF+CRO to treat MRSA or GISA IE.

scholarly journals Real-Time PCR Reveals Rapid Dissemination of Leptospira interrogans after Intraperitoneal and Conjunctival Inoculation of Hamsters

2016 ◽  
Vol 84 (7) ◽  
pp. 2105-2115 ◽  
Author(s):  
Elsio A. Wunder ◽  
Claudio P. Figueira ◽  
Gisele R. Santos ◽  
Kristel Lourdault ◽  
Michael A. Matthias ◽  
...  
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Low Dose ◽  
High Dose ◽  
Leptospira Interrogans ◽  
Content Type ◽  
Model Studies ◽  
Time To Peak ◽  
Passage Number ◽  
Intraperitoneal Infection

The pathogenLeptospira interrogansis a highly motile spirochete that causes acute and fulminant infections in humans and other accidental hosts. Hematogenous dissemination is important for infection by the pathogen but remains poorly understood because few animal model studies have used sensitive tools to quantify the bacteria. We evaluated the kinetics of leptospiral infection in Golden Syrian hamsters by a sensitive quantitative real-time PCR (TaqMan) withlipl32as the target gene. The dissemination and bacterial burden were measured after intraperitoneal infection with a high dose (108) or low dose (2.5 × 102) of leptospires. We also examined the conjunctival challenge route to mimic the natural history of infection. Quantification of leptospires in perfused animals revealed that pathogens were detected in all organs of intraperitoneally infected hamsters, including the eye and brain, within 1 h after inoculation of 108virulentL. interrogansbacteria. Peaks of 105to 108leptospires per gram or per milliliter were achieved in blood and all tissues between day 4 and day 8 after intraperitoneal inoculation of high- and low-dose challenges, respectively, coinciding with macroscopic and histological changes. The conjunctival route resulted in a delay in the time to peak organ burden in comparison to intraperitoneal infection, indicating that although infection could be established, penetration efficiency was low across this epithelial barrier. Surprisingly, infection with a large inoculum of high-passage-number attenuatedL. interrogansstrains resulted in dissemination to all organs in the first 4 days postinfection, albeit with a lower burden, followed by clearance from the blood and organs 7 days postinfection and survival of all animals. These results demonstrate that leptospiral dissemination and tissue invasion occur. In contrast, development of a critical level of tissue burden and pathology are dependent on the virulence of the infecting strain.

scholarly journals Rapid Isolation and Susceptibility Testing of Leptospira spp. Using a New Solid Medium, LVW Agar

2012 ◽  
Vol 57 (1) ◽  
pp. 297-302 ◽  
Author(s):  
Vanaporn Wuthiekanun ◽  
Premjit Amornchai ◽  
Daniel H. Paris ◽  
Sayan Langla ◽  
Janjira Thaipadunpanit ◽  
...  
Keyword(s):  
Growth Rate ◽  
Antimicrobial Susceptibility ◽  
Rapid Growth ◽  
Susceptibility Testing ◽  
Solid Medium ◽  
Initial Period ◽  
Penicillin G ◽  
Clinical Samples ◽  
Rabbit Serum ◽  
Content Type

ABSTRACTPathogenicLeptospiraspp., the causative agents of leptospirosis, are slow-growing Gram-negative spirochetes. Isolation ofLeptospirafrom clinical samples and testing of antimicrobial susceptibility are difficult and time-consuming. Here, we describe the development of a new solid medium that facilitates more-rapid growth ofLeptospiraspp. and the use of this medium to evaluate the Etest's performance in determining antimicrobial MICs to drugs in common use for leptospirosis. The medium was developed by evaluating the effects of numerous factors on the growth rate ofLeptospira interrogansstrain NR-20157. These included the type of base agar, the concentration of rabbit serum (RS), and the concentration and duration of CO2incubation during the initial period of culture. The highest growth rate of NR-20157 was achieved using a Noble agar base supplemented with 10% RS (named LVW agar), with an initial incubation at 30°C in 5% CO2for 2 days prior to continuous culture in air at 30°C. These conditions were used to develop the Etest for three species,L. interrogans(NR-20161),L. kirschnerii(NR-20327), andL. borgpetersenii(NR-20151). The MICs were read on day 7 for all samples. The Etest was then performed on 109 isolates of pathogenicLeptospiraspp. The MIC90values for penicillin G, doxycycline, cefotaxime, ceftriaxone, and chloramphenicol were 0.64 units/ml and 0.19, 0.047, 0.5, and 2 μg/ml, respectively. The use of LVW agar, which enables rapid growth, isolation of single colonies, and simple antimicrobial susceptibility testing forLeptospiraspp., provides an opportunity for new areas of fundamental and applied research.

Dual-isotope single-photon emission computerized tomography scanning in patients with glioblastoma multiforme: association with patient survival and histopathological characteristics of tumor after high-dose radiotherapy

1998 ◽  
Vol 89 (1) ◽  
pp. 60-68 ◽  
Author(s):  
Richard B. Schwartz ◽  
B. Leonard Holman ◽  
Joseph F. Polak ◽  
Basem M. Garada ◽  
Marc S. Schwartz ◽  
...  
Keyword(s):  
Survival Rate ◽  
Glioblastoma Multiforme ◽  
Single Photon ◽  
Photon Emission ◽  
High Dose ◽  
Term Survival ◽  
Content Type ◽  
Dual Isotope ◽  
Fine Print

Object. The study was conducted to determine the association between dual-isotope single-photon emission computerized tomography (SPECT) scanning and histopathological findings of tumor recurrence and survival in patients treated with high-dose radiotherapy for glioblastoma multiforme. Methods. Studies in which SPECT with 201Tl and 99mTc-hexamethypropyleneamine oxime (HMPAO) were used were performed 1 day before reoperation in 47 patients with glioblastoma multiforme who had previously been treated by surgery and high-dose radiotherapy. Maximum uptake of 201Tl in the lesion was expressed as a ratio to that in the contralateral scalp, and uptake of 99mTc-HMPAO was expressed as a ratio to that in the cerebellar cortex. Patients were stratified into groups based on the maximum radioisotope uptake values in their tumor beds. The significance of differences in patient gender, histological characteristics of tissue at reoperation, and SPECT uptake group with respect to 1-year survival was elucidated by using the chi-square statistic. Comparisons of patient ages and time to tumor recurrence as functions of 1-year survival were made using the t-test. Survival data at 1 year were presented according to the Kaplan—Meier method, and the significance of potential differences was evaluated using the log-rank method. The effects of different variables (tumor type, time to recurrence, and SPECT grouping) on long-term survival were evaluated using Cox proportional models that controlled for age and gender. All patients in Group I (201Tl ratio < 2 and 99mTc-HMPAO ratio < 0.5) showed radiation changes in their biopsy specimens: they had an 83.3% 1-year survival rate. Group II patients (201T1 ratio < 2 and 99mTc-HMPAO ratio of ≥ 0.5 or 201Tl ratio between 2 and 3.5 regardless of 99mTc-HMPAO ratio) had predominantly infiltrating tumor (66.6%); they had a 29.2% 1-year survival rate. Almost all of the patients in Group III (201Tl ratio > 3.5 and 99mTc-HMPAO ratio ≥ 0.5) had solid tumor (88.2%) and they had a 6.7% 1-year survival rate. Histological data were associated with 1-year survival (p < 0.01); however, SPECT grouping was more closely associated with 1-year survival (p < 0.001) and was the only variable significantly associated with long-term survival (p < 0.005). Conclusions. Dual-isotope SPECT data correlate with histopathological findings made at reoperation and with survival in patients with malignant gliomas after surgical and high-dose radiation therapy.

Gamma knife radiosurgery in patients with advanced breast cancer undergoing bone marrow transplant

2002 ◽  
Vol 97 ◽  
pp. 663-665 ◽  
Author(s):  
Kenneth J. Levin ◽  
Emad F. Youssef ◽  
Andrew E. Sloan ◽  
Rajiv Patel ◽  
Rana K. Zabad ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Advanced Breast Cancer ◽  
Gamma Knife ◽  
Gamma Knife Radiosurgery ◽  
High Dose Chemotherapy ◽  
Advanced Breast ◽  
High Dose ◽  
Initial Management ◽  
Content Type ◽  
Fine Print

Object. Recent studies have suggested a high incidence of cognitive deficits in patients undergoing high-dose chemotherapy, which appears to be dose related. Whole-brain radiotherapy (WBRT) has previously been associated with cognitive impairment. The authors attempted to use gamma knife radiosurgery (GKS) to delay or avoid WBRT in patients with advanced breast cancer treated with high-dose chemotherapy and autologous bone marrow transplantation (HDC/ABMT) in whom brain metastases were diagnosed. Methods. A retrospective review of our experience from 1996 to 2001 was performed to identify patients who underwent HDC/ABMT for advanced breast cancer and brain metastasis. They were able to conduct GKS as initial management to avoid or delay WBRT in 12 patients following HDC/ABMT. All patients were women. The median age was 48 years (range 30–58 years). The Karnofsky Performance Scale score was 70 (range 60–90). All lesions were treated with a median prescription dose of 17 Gy (range 15–18 Gy) prescribed to the 50% isodose. Median survival was 11.5 months. Five patients (42%) had no evidence of central nervous system disease progression and no further treatment was given. Four patients were retreated with GKS and three of them eventually received WBRT as well. Two patients were treated with WBRT as the primary salvage therapy. The median time to retreatment with WBRT was 8 months after the initial GKS. Conclusions. Gamma knife radiosurgery can be effectively used for the initial management of brain metastases to avoid or delay WBRT in patients treated previously with HDC, with acceptable survival and preserved cognitive function.

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