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In vitro spectrum of pexiganan activity when tested against pathogens from diabetic foot infections and with selected resistance mechanisms.

ABSTRACT: Pexiganan, a 22-amino-acid synthetic cationic peptide, is currently in phase 3 clinical trials as a topical antimicrobial agent for the treatment of mild infections associated with diabetic foot ulcers. Bacterial isolates from the 2013 SENTRY Antimicrobial Surveillance Program designated as pathogens from diabetic foot infections (DFI) and Gram-negative and -positive pathogens from various infection types that harbored selected resistance mechanisms/phenotypes were tested against pexiganan in reference cation-adjusted Mueller-Hinton broth. The MIC50 and MIC90 against all organisms tested from DFI were 16 and 32 ?g/ml, respectively. Escherichia coli, Klebsiella pneumoniae, Citrobacter koseri, Enterobacter cloacae, Acinetobacter species, and Pseudomonas aeruginosa MIC values ranged from 8 to 16 ?g/ml. Pexiganan MIC values among Staphylococcus aureus (methicillin-resistant S. aureus [MRSA] and methicillin-susceptible S. aureus [MSSA]), beta-hemolytic streptococci, and Enterococcus faecium ranged from 8 to 32 ?g/ml. Pexiganan activity was not adversely affected for members of the family Enterobacteriaceae or P. aeruginosa that produced ?-lactamases or resistance mechanisms to other commonly used antimicrobial agents. Decreased susceptibility to vancomycin did not affect pexiganan activity against S. aureus or E. faecium. Enterococcus faecalis appears to be intrinsically less susceptible to pexiganan (MIC, 32 to 256 ?g/ml). The "all organism" MIC90 of 32 ?g/ml for pexiganan in this study was >250-fold below the pexiganan concentration in the cream/delivery vehicle being developed for topical use.

SUBMITTER: Flamm RK

PROVIDER: S-EPMC4325814 | biostudies-literature | 2015 Mar

REPOSITORIES: biostudies-literature

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In vitro spectrum of pexiganan activity when tested against pathogens from diabetic foot infections and with selected resistance mechanisms.

Flamm Robert K RK Rhomberg Paul R PR Simpson Katie M KM Farrell David J DJ Sader Helio S HS Jones Ronald N RN

Antimicrobial agents and chemotherapy 20150112 3

Pexiganan, a 22-amino-acid synthetic cationic peptide, is currently in phase 3 clinical trials as a topical antimicrobial agent for the treatment of mild infections associated with diabetic foot ulcers. Bacterial isolates from the 2013 SENTRY Antimicrobial Surveillance Program designated as pathogens from diabetic foot infections (DFI) and Gram-negative and -positive pathogens from various infection types that harbored selected resistance mechanisms/phenotypes were tested against pexiganan in re ...[more]

PMID: 25583717

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Project description:ObjectiveThe purpose of this study was to evaluate the disparities in the outcomes of White, African American (AA) and non-AA minority (Hispanics and Native Americans (NA)), patients admitted in the hospitals with diabetic foot infections (DFIs).Research design and methodsThe HCUP-Nationwide Inpatient Sample (2002 to 2015) was queried to identify patients who were admitted to the hospital for management of DFI using ICD-9 codes. Outcomes evaluated included minor and major amputations, open or endovascular revascularization, and hospital length of stay (LOS). Incidence for amputation and open or endovascular revascularization were evaluated over the study period. Multivariable regression analyses were performed to assess the association between race/ethnicity and outcomes.ResultsThere were 150,701 admissions for DFI, including 98,361 Whites, 24,583 AAs, 24,472 Hispanics, and 1,654 Native Americans (NAs) in the study cohort. Overall, 45,278 (30%) underwent a minor amputation, 9,039 (6%) underwent a major amputation, 3,151 underwent an open bypass, and 8,689 had an endovascular procedure. There was a decreasing incidence in major amputations and an increasing incidence of minor amputations over the study period (P < .05). The risks for major amputation were significantly higher (all p<0.05) for AA (OR 1.4, 95%CI 1.4,1.5), Hispanic (OR 1.3, 95%CI 1.3,1.4), and NA (OR 1.5, 95%CI 1.2,1.8) patients with DFIs compared to White patients. Hispanics (OR 1.3, 95%CI 1.2,1.5) and AAs (OR 1.2, 95%CI 1.1,1.4) were more likely to receive endovascular intervention or open bypass than Whites (all p<0.05). NA patients with DFI were less likely to receive a revascularization procedure (OR 0.6, 95%CI 0.3, 0.9, p = 0.03) than Whites. The mean hospital length of stay (LOS) was significantly longer for AAs (9.2 days) and Hispanics (8.6 days) with DFIs compared to Whites (8.1 days, p<0.001).ConclusionDespite a consistent incidence reduction of amputation over the past decade, racial and ethnic minorities including African American, Hispanic, and Native American patients admitted to hospitals with DFIs have a consistently significantly higher risk of major amputation and longer hospital length of stay than their White counterparts. Native Americans were less likely to receive revascularization procedures compared to other minorities despite exhibiting an elevated risk of an amputation. Further study is required to address and limit racial and ethnic disparities and to further promote equity in the treatment and outcomes of these at-risk patients.

Project description:Invasive fungal infections due to Candida albicans, Aspergillus fumigatus, and Cryptococcus neoformans constitute a substantial threat to hospitalized immunocompromised patients. Further, the presence of drug-recalcitrant biofilms on medical devices and emergence of drug-resistant fungi, such as Candida auris, introduce treatment challenges with current antifungal drugs. Worse, currently there is no approved drug capable of obviating preformed biofilms, which increase the chance of infection relapses. Here, we screened a small-molecule New Prestwick Chemical Library, consisting of 1,200 FDA-approved off-patent drugs against C. albicans, C. auris, and A. fumigatus, to identify those that inhibit growth of all three pathogens. Inhibitors were further prioritized for their potency against other fungal pathogens and their ability to kill preformed biofilms. Our studies identified the bis-biguanide alexidine dihydrochloride (AXD) as a drug with the highest antifungal and antibiofilm activity against a diverse range of fungal pathogens. Finally, AXD significantly potentiated the efficacy of fluconazole against biofilms, displayed low mammalian cell toxicity, and eradicated biofilms growing in mouse central venous catheters in vivo, highlighting its potential as a pan-antifungal drug.IMPORTANCE The prevalence of fungal infections has seen a rise in the past decades due to advances in modern medicine leading to an expanding population of device-associated and immunocompromised patients. Furthermore, the spectrum of pathogenic fungi has changed, with the emergence of multidrug-resistant strains such as C. auris High mortality related to fungal infections points to major limitations of current antifungal therapy and an unmet need for new antifungal drugs. We screened a library of repurposed FDA-approved inhibitors to identify compounds with activities against a diverse range of fungi in varied phases of growth. The assays identified alexidine dihydrochloride (AXD) to have pronounced antifungal activity, including against preformed biofilms, at concentrations lower than mammalian cell toxicity. AXD potentiated the activity of fluconazole and amphotericin B against Candida biofilms in vitro and prevented biofilm growth in vivo Thus, AXD has the potential to be developed as a pan-antifungal, antibiofilm drug.

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In vitro spectrum of pexiganan activity when tested against pathogens from diabetic foot infections and with selected resistance mechanisms.

Publications

In vitro spectrum of pexiganan activity when tested against pathogens from diabetic foot infections and with selected resistance mechanisms.

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