Update on Acinetobacter Species: Mechanisms of Antimicrobial Resistance and Contemporary In Vitro Activity of Minocycline and Other Treatment Options

ABSTRACT Human African trypanosomiasis is a devastating disease with only a few treatment options, including pentamidine. Diamidine compounds such as pentamidine, DB75, and DB820 are potent antitrypanosomal compounds. Previous investigations have shown that diamidines accumulate to high concentrations in trypanosomes. However, the mechanism of action of this class of compounds remains unknown. A long-hypothesized mechanism of action has been binding to DNA and interference with DNA-associated enzymes. The fluorescent diamidines, DB75 and DB820, have been shown to localize not only in the DNA-containing nucleus and kinetoplast of trypanosomes but also to the acidocalcisomes. Here we investigate two series of analogs of DB75 and DB820 with various levels of in vitro antitrypanosomal activity to determine whether any correlation exists between trypanosome accumulation, distribution, and in vitro activity. Despite wide ranges of in vitro antitrypanosomal activity, all of the compounds investigated accumulated to millimolar concentrations in trypanosomes over a period of 8 h. Interestingly, some of the less potent compounds accumulated to concentrations much higher than those of more potent compounds. All of the compounds were localized to the DNA-containing nucleus and/or kinetoplast, and many were also found in the acidocalcisomes. Accumulation in the nucleus and kinetoplast should be important to the mechanism of action of these compounds. The acidocalcisomes may also play a role in the mechanism of action of these compounds. This investigation suggests that the extent of accumulation alone is not responsible for killing trypanosomes and that organelle-specific accumulation may not predict in vitro activity.

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Multidisciplinary Preclinical Investigations on Three Oxamniquine Analogues as Novel Treatment Options for Schistosomiasis

10.26434/chemrxiv.12102894 ◽

2020 ◽

Author(s):

Valentin Buchter ◽

Yih Ching Ong ◽

François Mouvet ◽

Abdallah Ladaycia ◽

Elise Lepeltier ◽

...

Keyword(s):

Treatment Options ◽

Vitro Activity ◽

In Vivo Studies ◽

In Vitro Activity ◽

Liver Model ◽

Novel Treatment ◽

Active Concentration ◽

Dynamics Simulations

<div>Schistosomiasis is a disease of poverty affecting millions of people. Praziquantel (PZQ), with its </div><div>strengths and weaknesses, is the only treatment available. We previously reported 3 lead </div><div>compounds derived from oxamniquine (OXA), an old antischistosomal drug: ferrocene‐containing </div><div>(Fc‐CH2‐OXA), ruthenocene‐containing (Rc‐CH2‐OXA) and benzene‐containing (Ph‐CH2‐OXA). </div><div>These derivatives showed excellent in vitro activity against both Schistosoma mansoni and S. </div><div>haematobium larvae and adult worms, and in vivo against S. mansoni. Encouraged by these </div><div>promising results, we followed a guided drug discovery process and report in this investigation on </div><div>metabolic stability studies, in vivo studies, computational simulations, and formulation studies. </div><div>Molecular dynamics simulations supported the in vitro results on the target protein. Though all </div><div>three compounds were poorly stable within an acidic environment, they were only slightly cleared </div><div>in the in vitro liver model. This is likely the reason as to why the promising in vitro activity did not </div><div>translate to in vivo activity. This limitation could not be saved by the formulation of lipid </div><div>nanocapsules as an intent to improve the in vivo activity. Further studies should focus on increasing </div><div>the compound’s bioavailability, in order to reach an active concentration in the parasite’s </div><div>microenvironment. </div>

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679. In vitro Activity of Cefiderocol (CFDC), a Novel Siderophore Cephalosporin, Against Difficult-to-Treat-Resistant (DTR) Gram-Negative Bacterial Pathogens From the Multi-National Sentinel Surveillance Study, SIDERO-WT (2014–2017)

Open Forum Infectious Diseases ◽

10.1093/ofid/ofz360.747 ◽

2019 ◽

Vol 6 (Supplement_2) ◽

pp. S309-S310 ◽

Cited By ~ 2

Author(s):

Christopher Longshaw ◽

Masakatsu Tsuji ◽

Meredith M Hackel ◽

Daniel F Sahm ◽

Yoshinori Yamano

Keyword(s):

Treatment Options ◽

Vitro Activity ◽

Surveillance Study ◽

Line Treatment ◽

In Vitro Activity ◽

First Line ◽

Gram Negative ◽

Acinetobacter Spp ◽

First Line Treatment

Abstract Background DTR organisms are defined as nonsusceptible to all high-efficacy, low-toxicity antibiotics (penicillins, cephalosporins, carbapenems, and quinolones), leaving physicians with limited first-line treatment options. Analyses of electronic health records have shown that patients with DTR Gram-negative bacterial infections are more likely to receive inappropriate antibiotic therapy, have longer hospital stay and increased risk of mortality. CFDC is a novel parenteral siderophore cephalosporin with potent activity against aerobic Gram-negative pathogens, including carbapenem-resistant strains. We evaluated the in vitro activity of CFDC and comparators against DTR pathogens collected by the SIDERO-WT surveillance study. Methods A total of 30,459 clinical isolates of Gram-negative bacilli were systematically collected from United States, Canada, and 11 EU countries during 2014–2017. MICs were determined by broth microdilution for a panel of 7 antibiotics, including CFDC, ceftazidime–avibactam (CZA), ceftolozane–tazobactam (C/T), colistin (CST), cefepime (FEP), meropenem (MEM), and ciprofloxacin (CIP) according to CLSI guidelines. All antibiotics were tested in cation-adjusted Mueller–Hinton broth (CAMHB) except CFDC, for which iron-depleted CAMHB was used. Susceptibility was determined according to CLSI interpretive breakpoints except CST, where EUCAST breakpoints were used. DTR pathogens were defined as being nonsusceptible to FEP, MEM, and CIP according to CLSI breakpoints. Results Among 30,459 Gram-negative isolates collected between 2014 and 2017, 9.3% were nonsusceptible to FEP, MEM, and CIP and could be defined as DTR. DTR was most frequently observed in Acinetobacter spp. (55.5%), followed by Burkholderia spp. (19%), Pseudomonas aeruginosa (9.5%), and Enterobacterales (2.7%). Of the 1,173 Stenotrophomonas maltophilia tested, 97% had MEM MIC of ≥8 mg/L; however, only 2.9% could be defined as DTR. Cefiderocol was the most active antibiotic tested against DTR isolates with 94.5% DTR-Acinetobacter spp., 98.3% DTR-P. aeruginosa, and 99.8% DTR-Enterobacterales susceptible (Table 1). Conclusion CFDC demonstrated potent activity against DTR Gram-negative pathogens with limited first-line treatment options. Disclosures All authors: No reported disclosures.

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In vitro susceptibility of common bacterial pathogens causing respiratory tract infections in Canada to lefamulin, a new pleuromutilin

Official Journal of the Association of Medical Microbiology and Infectious Disease Canada ◽

10.3138/jammi-2020-0043 ◽

2021 ◽

Vol 6 (2) ◽

pp. 149-162

Author(s):

Robert M Taylor ◽

James A Karlowsky ◽

Melanie R Baxter ◽

Heather J Adam ◽

Andrew Walkty ◽

...

Keyword(s):

Respiratory Tract ◽

Treatment Options ◽

Vitro Activity ◽

Health Concern ◽

In Vitro Activity ◽

Bacterial Isolates ◽

In Vitro Susceptibility ◽

Broth Microdilution Method ◽

Tract Infections

Background: Community-acquired pneumonia (CAP) is a significant global health concern. Pathogens causing CAP demonstrate increasing resistance to commonly prescribed empiric treatments. Resistance in Streptococcus pneumoniae, the most prevalent bacterial cause of CAP, has been increasing worldwide, highlighting the need for improved antibacterial agents. Lefamulin, a novel pleuromutilin, is a recently approved therapeutic agent highly active against many lower respiratory tract pathogens. However, to date minimal data are available to describe the in vitro activity of lefamulin against bacterial isolates associated with CAP. Methods: Common bacterial causes of CAP obtained from both lower respiratory and blood specimen isolates cultured by hospital laboratories across Canada were submitted to the annual CANWARD study’s coordinating laboratory in Winnipeg, Canada, from January 2015 to October 2018. A total of 876 bacterial isolates were tested against lefamulin and comparator agents using the Clinical and Laboratory Standards Institute (CLSI) reference broth microdilution method, and minimum inhibitory concentrations (MICs) were interpreted using accepted breakpoints. Results: All S. pneumoniae isolates tested from both respiratory (n = 315) and blood specimens (n = 167) were susceptible to lefamulin (MIC ≤0.5 μg/mL), including isolates resistant to penicillins, clarithromycin, doxycycline, and trimethoprim–sulfamethoxazole. Lefamulin also inhibited 99.0% of Haemophilus influenzae isolates (regardless of β-lactamase production) (99 specimens; MIC ≤2 μg/mL) and 95.7% of methicillin-susceptible Staphylococcus aureus (MSSA) (MIC ≤0.25 μg/mL; 70 specimens) at their susceptible breakpoints. Conclusions: Lefamulin demonstrated potent in vitro activity against all respiratory isolates tested and may represent a significant advancement in empiric treatment options for CAP.

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